The laser-assisted manufacturing technology has significant advantages in meeting various demands such as complex structures, functional integration, customized devices, and cost-effectiveness, which makes it a highly attractive option for fabricating sensors. In this review, the latest advancements and strategies in intelligent sensor development through laser processing were surveyed and outlined following the interaction of laser and materials. Laser-assisted manufacturing technologies have been extensively applied in materials science and device processing. Firstly, laser technology can be utilized in a wide range of materials, encompassing carbon-based materials, metals, and metallic oxides. In the field of device scale processing, laser manufacturing is widely used in micro/nano structures, planar device construction, and stereoscopic electronic devices such as cutting, engraving, and lithography. Additionally, laser technology provides robust support for sensor applications, covering fields such as pressure sensing, temperature sensing, gas sensing, and biosensors. Furthermore, laser considerably serves in real application areas such as multifunctional sensing systems, actuators, and robots. The widespread application of laser manufacturing technology in sensor platform fabrication offers effective solutions for realizing the miniaturization, multifunctionality, and integration of sensors.

Neuromorphic computing extends beyond sequential processing modalities and outperforms traditional von Neumann architectures in implementing more complicated tasks, e.g., pattern processing, image recognition, and decision making. It features parallel interconnected neural networks, high fault tolerance, robustness, autonomous learning capability, and ultralow energy dissipation. The algorithms of artificial neural network (ANN) have also been widely used because of their facile self-organization and self-learning capabilities, which mimic those of the human brain. To some extent, ANN reflects several basic functions of the human brain and can be efficiently integrated into neuromorphic devices to perform neuromorphic computations. This review highlights recent advances in neuromorphic devices assisted by machine learning algorithms. First, the basic structure of simple neuron models inspired by biological neurons and the information processing in simple neural networks are particularly discussed. Second, the fabrication and research progress of neuromorphic devices are presented regarding to materials and structures. Furthermore, the fabrication of neuromorphic devices, including stand-alone neuromorphic devices, neuromorphic device arrays, and integrated neuromorphic systems, is discussed and demonstrated with reference to some respective studies. The applications of neuromorphic devices assisted by machine learning algorithms in different fields are categorized and investigated. Finally, perspectives, suggestions, and potential solutions to the current challenges of neuromorphic devices are provided.

With the rise of artificial intelligence (AI), neuromorphic sensory systems that emulate the five basic human sensations including tactility, audition, olfaction, gustation, and vision have attracted significant attention. In particular, research on integrating sensors with artificial synapses is being carried out extensively. These studies offer valuable opportunities for making another breakthrough in AI technology, including autonomous systems, real-time monitoring systems, and human-machine interactions. In this review, we introduce promising reports of neuromorphic sensory systems. Specifically, the core sensing material, device architecture, fabrication process, and applications of the proposed systems are presented in detail. Finally, the unsolved challenges and the prospects of neuromorphic sensory systems are discussed.

Additive manufacturing (AM) offers the unique capability of directly creating three-dimensional complicated ceramic components with high process flexibility and outstanding geometry controllability. However, current ceramic AM technology is mainly limited to the creation of a single material, which falls short of meeting the multiple functional requirements under increasingly harsh service circumstances. Ceramic multi-material additive manufacturing (MMAM) technology has great potential for integrally producing multi-dimensional multi-functional components, allowing for point-by-point precision manufacturing of programmable performance/functions. However, there is a huge gap between the capabilities of the existing ceramic MMAM technology and the requirements for industrial application. In this review, we discuss and summarize the research status of ceramic MMAM technology from the perspectives of feedstock selection, printing process, post-processing, component performance, and application. Throughout the discussion, the challenges associated with ceramic MMAM such as heterogeneous material coupled printing, heterogeneous interfacial bonding, and co-sintering densification have been put forward. This review aims to bridge the gap between AM technologies and the requirements for multifunctional ceramic components by analyzing the existing limitations in ceramic MMAM and pointing out future needs.

Wire-arc directed energy deposition (wire-arc DED) enables the fabrication of large-scale metal components with rapid manufacturing ability and diverse material selection, making it a compelling technology in industries and defenses. However, challenges in both macroscale and microscale defects still limit printed component widespread applications. Recent advances in automatic and intelligent technologies have brought a range of quality controllable strategies to the forefront. This review covers these new strategies for the printing component, including path planning, process monitoring, auxiliary processes, and post processing, while discussing the expectation for structure and quality improvement. In addition, the work brings new areas of intelligent wire-arc DED development, including advances in digital twin, visualization, and human-processing interaction to promote its performance. It is anticipated that a focus on intelligent system will be key to smart and high-quality manufacturing for future wire-arc DED.

Real-time sensory signal monitoring systems are crucial for continuous health tracking and enhancing human-interface technologies in virtual reality/augmented reality applications. Recent advancements in micro/nanofabrication technologies have enabled wearable and implantable sensors to achieve sufficient sensitivity for measuring subtle sensory signals, while integration with wireless communication technologies allows for real-time monitoring and closed-loop user feedback. However, highly sensitive sensing materials face challenges, as their detection results can easily be altered by external factors such as bending, temperature, and humidity. This review discusses methods for decoupling various stimuli and their applications in human interfaces. We cover the latest advancements in decoupled systems, including the design of sensing materials using micro/nanostructured materials, 3-dimensional (3D) sensory system architectures, and Artificial intelligence (AI)-based signal decoupling processing techniques. Additionally, we highlight key applications in robotics, wearable, and implantable health monitoring made possible by these decoupled systems. Finally, we suggest future research directions to address the remaining challenges of developing decoupled artificial sensory systems that are resilient to external stimuli.

Artificial sensory systems mimic the five human senses to facilitate data interaction between the real and virtual worlds. Accurate data analysis is crucial for converting external stimuli from each artificial sense into user-relevant information, yet conventional signal processing methods struggle with the massive scale, noise, and artificial sensory systems characteristics of data generated by artificial sensory devices. Integrating artificial intelligence (AI) is essential for addressing these challenges and enhancing the performance of artificial sensory systems, making it a rapidly growing area of research in recent years. However, no studies have systematically categorized the output functions of these systems or analyzed the associated AI algorithms and data processing methods. In this review, we present a systematic overview of the latest AI techniques aimed at enhancing the cognitive capabilities of artificial sensory systems replicating the five human senses: touch, taste, vision, smell, and hearing. We categorize the AI-enabled capabilities of artificial sensory systems into four key areas: cognitive simulation, perceptual enhancement, adaptive adjustment, and early warning. We introduce specialized AI algorithms and raw data processing methods for each function, designed to enhance and optimize sensing performance. Finally, we offer a perspective on the future of AI-integrated artificial sensory systems, highlighting technical challenges and potential real-world application scenarios for further innovation. Integration of AI with artificial sensory systems will enable advanced multimodal perception, real-time learning, and predictive capabilities. This will drive precise environmental adaptation and personalized feedback, ultimately positioning these systems as foundational technologies in smart healthcare, agriculture, and automation.

Prosthetic devices designed to assist individuals with damaged or missing body parts have made significant strides, particularly with advancements in machine intelligence and bioengineering. Initially focused on movement assistance, the field has shifted towards developing prosthetics that function as seamless extensions of the human body. During this progress, a key challenge remains the reduction of interface artifacts between prosthetic components and biological tissues. Soft electronics offer a promising solution due to their structural flexibility and enhanced tissue adaptability. However, achieving full integration of prosthetics with the human body requires both artificial perception and efficient transmission of physical signals. In this context, synaptic devices have garnered attention as next-generation neuromorphic computing elements because of their low power consumption, ability to enable hardware-based learning, and high compatibility with sensing units. These devices have the potential to create artificial pathways for sensory recognition and motor responses, forming a “sensory-neuromorphic system” that emulates synaptic junctions in biological neurons, thereby connecting with impaired biological tissues. Here, we discuss recent developments in prosthetic components and neuromorphic applications with a focus on sensory perception and sensorimotor actuation. Initially, we explore a prosthetic system with advanced sensory units, mechanical softness, and artificial intelligence, followed by the hardware implementation of memory devices that combine calculation and learning functions. We then highlight the importance and mechanisms of soft-form synaptic devices that are compatible with sensing units. Furthermore, we review an artificial sensory-neuromorphic perception system that replicates various biological senses and facilitates sensorimotor loops from sensory receptors, the spinal cord, and motor neurons. Finally, we propose insights into the future of closed-loop neuroprosthetics through the technical integration of soft electronics, including bio-integrated sensors and synaptic devices, into prosthetic systems.

Today, energy is essential for every aspect of human life, including clothing, food, housing and transportation. However, traditional energy resources are insufficient to meet our modern needs. Self-powered sensing devices emerge as promising alternatives, offering sustained operation without relying on external power sources. Leveraging advancements in materials and manufacturing research, these devices can autonomously harvest energy from various sources. In this review, we focus on the current landscape of self-powered wearable sensors, providing a concise overview of energy harvesting technologies, conversion mechanisms, structural or material innovations, and energy storage platforms. Then, we present experimental advances in different energy sources, showing their underlying mechanisms, and the potential for energy acquisition. Furthermore, we discuss the applications of self-powered flexible sensors in diverse fields such as medicine, sports, and food. Despite significant progress in this field, widespread commercialization will necessitate enhanced sensor detection abilities, improved design factors for adaptable devices, and a balance between sensitivity and standardization.

Magnetoresistive random access memory (MRAM) is a promising non-volatile memory technology that can be utilized as an energy and space-efficient storage and computing solution, particularly in cache functions within circuits. Although MRAM has achieved mass production, its manufacturing process still remains challenging, resulting in only a few semiconductor companies dominating its production. In this review, we delve into the materials, processes, and devices used in MRAM, focusing on both the widely adopted spin transfer torque MRAM and the next-generation spin-orbit torque MRAM. We provide an overview of their operational mechanisms and manufacturing technologies. Furthermore, we outline the major hurdles faced in MRAM manufacturing and propose potential solutions in detail. Then, the applications of MRAM in artificial intelligent hardware are introduced. Finally, we present an outlook on the future development and applications of MRAM.

This comprehensive review explores the multifaceted landscape of skin bioprinting, revolutionizing dermatological research. The applications of skin bioprinting utilizing techniques like extrusion-, droplet-, laser- and light-based methods, with specialized bioinks for skin biofabrication have been critically reviewed along with the intricate aspects of bioprinting hair follicles, sweat glands, and achieving skin pigmentation. Challenges remain with the need for vascularization, safety concerns, and the integration of automated processes for effective clinical translation. The review further investigates the incorporation of biosensor technologies, emphasizing their role in monitoring and enhancing the wound healing process. While highlighting the remarkable progress in the field, critical limitations and concerns are critically examined to provide a balanced perspective. This synthesis aims to guide scientists, engineers, and healthcare providers, fostering a deeper understanding of the current state, challenges, and future directions in skin bioprinting for transformative applications in tissue engineering and regenerative medicine.

Electrohydrodynamic (EHD) jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale structures. EHD printing is particularly advantageous for the fabrication on flexible or non-flat substrates and of large aspect ratio micro/nanostructures and composite multi-material structures. Despite this, EHD printing has yet to be fully industrialised due to its low throughput, which is primarily caused by the limitations of serial additive printing technology. The parallel multi-nozzle array-based process has become the most promising option for EHD printing to achieve large-scale printing by increasing the number of nozzles to realise multichannel parallel printing. This paper reviews the recent development of multi-nozzle EHD printing technology, analyses jet motion with multi-nozzle, explains the origins of the electric field crosstalk effect under multi-nozzle and discusses several widely used methods for overcoming it. This work also summarises the impact of different process parameters on multi-nozzle EHD printing and describes the current manufacturing process using multi-nozzle as well as the method by which they can be realised independently. In addition, it presents an additional significant utilisation of multi-nozzle printing aside from enhancing single-nozzle production efficiency, which is the production of composite phase change materials through multi-nozzle. Finally, the future direction of multi-nozzle EHD printing development is discussed and envisioned.

Benefiting from the widespread potential applications in the era of the Internet of Thing and metaverse, triboelectric and piezoelectric nanogenerators (TENG & PENG) have attracted considerably increasing attention. Their outstanding characteristics, such as self-powered ability, high output performance, integration compatibility, cost-effectiveness, simple configurations, and versatile operation modes, could effectively expand the lifetime of vastly distributed wearable, implantable, and environmental devices, eventually achieving self-sustainable, maintenance-free, and reliable systems. However, current triboelectric/piezoelectric based active (i.e. self-powered) sensors still encounter serious bottlenecks in continuous monitoring and multimodal applications due to their intrinsic limitations of monomodal kinetic response and discontinuous transient output. This work systematically summarizes and evaluates the recent research endeavors to address the above challenges, with detailed discussions on the challenge origins, designing strategies, device performance, and corresponding diverse applications. Finally, conclusions and outlook regarding the research gap in self-powered continuous multimodal monitoring systems are provided, proposing the necessity of future research development in this field.

Piezoelectric and triboelectric effects are of growing interest for facilitating high-sensitivity and self-powered tactile sensor applications. The working principles of piezoelectric and triboelectric nanogenerators provide strategies for enhancing output voltage signals to achieve high sensitivity. Increasing the piezoelectric constant and surface triboelectric charge density are key factors in this enhancement. Methods such as annealing processes, doping techniques, grain orientation controls, crystallinity controls, and composite structures can effectively enhance the piezoelectric constant. For increasing triboelectric output, surface plasma treatment, charge injection, microstructuring, control of dielectric constant, and structural modification are effective methods. The fabrication methods present significant opportunities in tactile sensor applications. This review article summarizes the overall piezoelectric and triboelectric fabrication processes from materials to device aspects. It highlights applications in pressure, touch, bending, texture, distance, and material recognition sensors. The conclusion section addresses challenges and research opportunities, such as limited flexibility, stretchability, decoupling from multi-stimuli, multifunctional sensors, and data processing.

Driven by the urgent demands for information technology, energy, and intelligent industry, third-generation semiconductor GaN has emerged as a pivotal component in electronic and optoelectronic devices. Fundamentally, piezoelectric polarization is the most essential feature of GaN materials. Incorporating piezotronics and piezo-phototronics, GaN materials synergize mechanical signals with electrical and optical signals, thereby achieving multi-field coupling that enhances device performance. Piezotronics regulates the carrier transport process in micro–nano devices, which has been proven to significantly improve the performance of devices (such as high electron mobility transistors and microLEDs) and brings many novel applications. This review examines GaN material properties and the theoretical foundations of piezotronics and phototronics. Furthermore, it delves into the fabrication and integration processes of GaN devices to achieve state-of-the-art performance. Additionally, this review analyzes the impact of introducing three-dimensional stress and regulatory forces on the electrical and optical output performance of devices. Moreover, it discusses the burgeoning applications of GaN devices in neural sensing, optoelectronic output, and energy harvesting. The potential of piezotronic-controlled GaN devices provides valuable insights for future research and the development of multi-functional, diversified electronic devices.

Magnetically responsive microstructured functional surface (MRMFS), capable of dynamically and reversibly switching the surface topography under magnetic actuation, provides a wireless, noninvasive, and instantaneous way to accurately control the microscale engineered surface. In the last decade, many studies have been conducted to design and optimize MRMFSs for diverse applications, and significant progress has been accomplished. This review comprehensively presents recent advancements and the potential prospects in MRMFSs. We first classify MRMFSs into one-dimensional linear array MRMFSs, two-dimensional planar array MRMFSs, and dynamic self-assembly MRMFSs based on their morphology. Subsequently, an overview of three deformation mechanisms, including magnetically actuated bending deformation, magnetically driven rotational deformation, and magnetically induced self-assembly deformation, are provided. Four main fabrication strategies employed to create MRMFSs are summarized, including replica molding, magnetization-induced self-assembly, laser cutting, and ferrofluid-infused method. Furthermore, the applications of MRMFS in droplet manipulation, solid transport, information encryption, light manipulation, triboelectric nanogenerators, and soft robotics are presented. Finally, the challenges that limit the practical applications of MRMFSs are discussed, and the future development of MRMFSs is proposed.

The cochlea is one of the most complex organs in the human body, exhibiting a complex interplay of characteristics in acoustic, mechanical, electrical, and biological functions. Functional cochlea models are an essential platform for studying hearing mechanics and are crucial for developing next-generation auditory prostheses and artificial hearing systems for sensorineural hearing restoration. Recent advances in additive manufacturing, organ-on-a-chip models, drug delivery platforms, and artificial intelligence have provided valuable insights into how to manufacture artificial cochlea models that more accurately replicate the complex anatomy and physiology of the inner ear. This paper reviews recent advancements in the applications of advanced manufacturing techniques in reproducing the physical, biological, and intelligent functions of the cochlea. It also outlines the current challenges to developing mechanically, electrically, and anatomically accurate functional models of the inner ear. Finally, this review identifies the major requirements and outlook for impactful research in this field going forward. Through interdisciplinary collaboration and innovation, these functional cochlea models are poised to drive significant advancements in hearing treatments, and ultimately enhance the quality of life for individuals with hearing loss.

Recurrent neural networks (RNNs) have proven to be indispensable for processing sequential and temporal data, with extensive applications in language modeling, text generation, machine translation, and time-series forecasting. Despite their versatility, RNNs are frequently beset by significant training expenses and slow convergence times, which impinge upon their deployment in edge AI applications. Reservoir computing (RC), a specialized RNN variant, is attracting increased attention as a cost-effective alternative for processing temporal and sequential data at the edge. RC's distinctive advantage stems from its compatibility with emerging memristive hardware, which leverages the energy efficiency and reduced footprint of analog in-memory and in-sensor computing, offering a streamlined and energy-efficient solution. This review offers a comprehensive explanation of RC's underlying principles, fabrication processes, and surveys recent progress in nano-memristive device based RC systems from the viewpoints of in-memory and in-sensor RC function. It covers a spectrum of memristive device, from established oxide-based memristive device to cutting-edge material science developments, providing readers with a lucid understanding of RC's hardware implementation and fostering innovative designs for in-sensor RC systems. Lastly, we identify prevailing challenges and suggest viable solutions, paving the way for future advancements in in-sensor RC technology.

In this review, we propose a comprehensive overview of additive manufacturing (AM) technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field, of which many are inspired by nature itself. It describes how new AM technologies (e.g. continuous liquid interface production and multiphoton polymerization, etc) and recent developments in more mature AM technologies (e.g. powder bed fusion, stereolithography, and extrusion-based bioprinting (EBB), etc) lead to more precise, efficient, and personalized biomedical components. EBB is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials, for instance, stress elimination for tissue engineering and regenerative medicine, negative or zero Poisson's ratio. By exploiting the designs of porous structures (e.g. truss, triply periodic minimal surface, plant/animal-inspired, and functionally graded lattices, etc), AM-made bioactive bone implants, artificial tissues, and organs are made for tissue replacement. The material palette of the AM metamaterials has high diversity nowadays, ranging from alloys and metals (e.g. cobalt–chromium alloys and titanium, etc) to polymers (e.g. biodegradable polycaprolactone and polymethyl methacrylate, etc), which could be even integrated within bioactive ceramics. These advancements are driving the progress of the biomedical field, improving human health and quality of life.

The capability for synergistic advancements in both making and shaping afforded by additive manufacturing (AM) enables the flexible production of high-performance components. Boosted by the growing demand for heat-resistant aluminum alloys in the moderate-temperature weight-critical applications, AM of heat-resistant aluminum alloys constitutes a burgeoning field. Although numerous advances have emerged in recent years, there remains a gap in the review literature elucidating the newly-developed alloy systems and critically evaluating the efficacy. This state-of-the-art review presents a detailed overview of recent achievements on the heat-resistant aluminum alloy development. It begins with the introduction of various AM technologies and the pros and cons of each technique are evaluated. The enhancement mechanisms associated with printability and high-temperature properties of AM aluminum alloys are then delineated. Thereafter, the various additively manufactured aluminum alloy systems are discussed with regard to the microstructure, heat resistance and high-temperature performance. An emphasis is put on the powder bed fusion-laser beam (PBF-LB) as it has garnered significant attention for heat-resistant aluminum alloys and the vast majority of the current studies are based on this technique. Finally, perspectives are outlined to provide guidance for future research.

Aero-engines, the core of air travel, rely on advanced high strength-toughness alloys (THSAs) such as titanium alloys, nickel-based superalloys, intermetallics, and ultra-high strength steel. The precision of cutting techniques is crucial for the manufacture of key components, including blades, discs, shafts, and gears. However, machining THSAs pose significant challenges, including high cutting forces and temperatures, which lead to rapid tool wear, reduced efficiency, and compromised surface integrity. This review thoroughly explores the current landscape and future directions of cutting techniques for THSAs in aero-engines. It examines the principles, mechanisms, and benefits of energy-assisted cutting technologies like laser-assisted machining and cryogenic cooling. The review assesses various tool preparation methods, their effects on tool performance, and strategies for precise shape and surface integrity control. It also outlines intelligent monitoring technologies for machining process status, covering aspects such as tool wear, surface roughness, and chatter, contributing to intelligent manufacturing. Additionally, it highlights emerging trends and potential future developments, including multi-energy assisted cutting mechanisms, advanced cutting tools, and collaborative control of structure shape and surface integrity, alongside intelligent monitoring software and hardware. This review serves as a reference for achieving efficient and high-quality manufacturing of THSAs in aero-engines.

Four-dimensional (4D) printing is regarded as a methodology that links 3D printing to time, which is characterized by the evolution of predetermined structures or functions for the printed object after applying stimulation. This dynamic feature endows 4D printing the potential to be intelligent, attracting wide attention from academia and industry. The transformation of shape and function is both obtained from the programming of the object endowed by the intrinsic characteristics of the material or by the manufacturing technology. Therefore, it is necessary to understand 4D printing from the perspective of both mechanism and manufacturing. Here, the state-of-the-art 4D printing polymer was summarized, beginning with the classifications, and leading to the mechanisms, stimulations, and technologies. The links and differences between 4D printing polymer and shape memory polymer, between 4D printing and 3D printing were highlighted. Finally, the biomedical applications were outlined and the perspectives were discussed.

Ta-based materials have gained significant interest for bioimplantable scaffolds because of their appropriate mechanical characteristics and biocompatibility. To overcome the serious limitation of bioinertness, there have been many efforts to enhance the bioactivity and osseointegration of Ta-based scaffolds through morphostructural and surface modifications. As scaffolds are implantable devices, sufficient bioactivity is needed to trigger the cellular functions required for tissue engineering. Consequently, a combination of materials and bioscience is needed to develop efficient Ta-based scaffolds, although reviews of this interdisciplinary field remain limited. This review aims to provide an overview of the main strategies to enhance the bioactivity of Ta-based scaffolds, describing the basic mechanisms and research methods of osseointegration, and the approaches to enhance bioactivity and osseointegration. These approaches are divided into three main sections: (i) alteration of the micromorphology, (ii) customization of the scaffold structure, and (iii) functionalization modifications (through alloying or the addition of surface coatings). Also provided are recent advances regarding biocompatibility assessment in vitro, osseointegration properties in vivo, and clinical trial results.

The ocean is the largest reservoir of renewable energy on earth, in which wave energy occupies an important position due to its high energy density and extensive distribution. As a cutting-edge technology, wave-driven triboelectric nanogenerators (W-TENGs) demonstrate substantial potential for ocean energy conversion and utilization. This paper provides a comprehensive review of W-TENGs, from materials manufacturing and structural fabrications to marine applications. It highlights the versatility in materials selection for W-TENGs and the potential for unique treatments to enhance output performance. With the development of materials science, researchers can manufacture materials with various properties as needed. The structural design and fabrication of W-TENGs is the pillar of converting wave energy to electrical energy. The flexible combination of TENG's multiple working modes and advanced manufacturing methods make W-TENGs' structures rich and diverse. Advanced technologies, such as three-dimensional printing, make manufacturing and upgrading W-TENGs more convenient and efficient. This paper summarizes their structures and elucidates their features and manufacturing processes. It should be noted that all efforts made in materials and structures are aimed at W-TENGs, having a bright application prospect. The latest studies on W-TENGs for effective application in the marine field are reviewed, and their feasibility and practical value are evaluated. Finally, based on a systematic review, the existing challenges at this stage are pointed out. More importantly, strategies to address these challenges and directions for future research efforts are also discussed. This review aims to clarify the recent advances in standardization and scale-up of W-TENGs to promote richer innovation and practice in the future.

Micro diamond tools are indispensable for the efficient machining of microstructured surfaces. The precision in tool manufacturing and cutting performance directly determines the processing quality of components. The manufacturing of high-quality micro diamond tools relies on scientific design methods and appropriate processing techniques. However, there is currently a lack of systematic review on the design and manufacturing methods of micro diamond tools in academia. This study systematically summarizes and analyzes modern manufacturing methods for micro diamond tools, as well as the impact of tool waviness, sharpness, and durability on machining quality. Subsequently, a design method is proposed based on the theory of cutting edge strength distribution to enhance tool waviness, sharpness, and durability. Finally, this paper presents current technical challenges faced by micro diamond tools along with potential future solutions to guide scientists in this field. The aim of this review is to contribute to the further development of the current design and manufacturing processes for micro diamond cutting tools.

High-bandwidth nano-positioning stages (NPSs) have boosted the advancement of modern ultra-precise, ultra-fast measurement and manufacturing technologies owing to their fast dynamic response, high stiffness and nanoscale resolution. However, the nonlinear actuation, lightly damped resonance and multi-axis cross-coupling effect bring significant challenges to the design, modeling and control of high-bandwidth NPSs. Consequently, numerous advanced works have been reported over the past decades to address these challenges. Here, this article provides a comprehensive review of high-bandwidth NPSs, which covers four representative aspects including mechanical design, system modeling, parameters optimization and high-bandwidth motion control. Besides, representative high-bandwidth NPSs applied to atomic force microscope and fast tool servo are highlighted. By providing an extensive overview of the design procedure for high-bandwidth NPSs, this review aims to offer a systemic solution for achieving operation with high speed, high accuracy and high resolution. Furthermore, remaining difficulties along with future developments in this fields are concluded and discussed.

Micro/nanorobots (MNRs) capable of performing tasks at the micro- and nanoscale hold great promise for applications in cutting-edge fields such as biomedical engineering, environmental engineering, and microfabrication. To cope with the intricate and dynamic environments encountered in practical applications, the development of high performance MNRs is crucial. They have evolved from single-material, single-function, and simple structure to multi-material, multi-function, and complex structure. However, the design and manufacturing of high performance MNRs with complex multi-material three-dimensional structures at the micro- and nanoscale pose significant challenges that cannot be addressed by conventional serial design strategies and single-process manufacturing methods. The material-interface-structure-function/performance coupled design methods and the additive/formative/subtractive composite manufacturing methods offer the opportunity to design and manufacture MNRs with multi-materials and complex structures under multi-factor coupling, thus paving the way for the development of high performance MNRs. In this paper, we take the three core capabilities of MNRs—mobility, controllability, and load capability—as the focal point, emphasizing the coupled design methods oriented towards their function/performance and the composite manufacturing methods for their functional structures. The limitations of current investigation are also discussed, and our envisioned future directions for design and manufacture of MNRs are shared. We hope that this review will provide a framework template for the design and manufacture of high performance MNRs, serving as a roadmap for researchers interested in this area.

Soft (flexible and stretchable) biosensors have great potential in real-time and continuous health monitoring of various physiological factors, mainly due to their better conformability to soft human tissues and organs, which maximizes data fidelity and minimizes biological interference. Most of the early soft sensors focused on sensing physical signals. Recently, it is becoming a trend that novel soft sensors are developed to sense and monitor biochemical signals in situ in real biological environments, thus providing much more meaningful data for studying fundamental biology and diagnosing diverse health conditions. This is essential to decentralize the healthcare resources towards predictive medicine and better disease management. To meet the requirements of mechanical softness and complex biosensing, unconventional materials, and manufacturing process are demanded in developing biosensors. In this review, we summarize the fundamental approaches and the latest and representative design and fabrication to engineer soft electronics (flexible and stretchable) for wearable and implantable biochemical sensing. We will review the rational design and ingenious integration of stretchable materials, structures, and signal transducers in different application scenarios to fabricate high-performance soft biosensors. Focus is also given to how these novel biosensors can be integrated into diverse important physiological environments and scenarios in situ, such as sweat analysis, wound monitoring, and neurochemical sensing. We also rethink and discuss the current limitations, challenges, and prospects of soft biosensors. This review holds significant importance for researchers and engineers, as it assists in comprehending the overarching trends and pivotal issues within the realm of designing and manufacturing soft electronics for biochemical sensing.

Sub-wavelength nanostructure lattices provide versatile platforms for light control and the basis for various novel phenomena and applications in physics, material science, chemistry, biology, and energy. The thriving study of nanostructure lattices is building on the remarkable progress of nanofabrication techniques, especially for the possibility of fabricating larger-area patterns while achieving higher-quality lattices, complex shapes, and hybrid materials units. In this review, we present a comprehensive review of techniques for large-area fabrication of optical nanostructure arrays, encompassing direct writing, self-assembly, controllable deposition, and nanoimprint/print methods. Furthermore, a particular focus is made on the recent improvement of unit accuracy and diversity, leading to integrated and multifunctional structures for devices and applications.

Triboelectric nanogenerators (TENGs) stand at the forefront of energy harvesting innovation, transforming mechanical energy into electrical power through triboelectrification and electrostatic induction. This groundbreaking technology addresses the urgent need for sustainable and renewable energy solutions, opening new avenues for self-powered systems. Despite their potential, TENGs face challenges such as material optimization for enhanced triboelectric effects, scalability, and improving conversion efficiency under varied conditions. Durability and environmental stability also pose significant hurdles, necessitating further research towards more resilient systems. Nature inspired TENG designs offer promising solutions by emulating biological processes and structures, such as the energy mechanisms of plants and the textured surfaces of animal skins. This biomimetic approach has led to notable improvements in material properties, structural designs, and overall TENG performance, including enhanced energy conversion efficiency and environmental robustness. The exploration into bio-inspired TENGs has unlocked new possibilities in energy harvesting, self-powered sensing, and wearable electronics, emphasizing reduced energy consumption and increased efficiency through innovative design. This review encapsulates the challenges and advancements in nature inspired TENGs, highlighting the integration of biomimetic principles to overcome current limitations. By focusing on augmented electrical properties, biodegradability, and self-healing capabilities, nature inspired TENGs pave the way for more sustainable and versatile energy solutions.

Because of their high safety, low cost, and high volumetric specific capacity, zinc-ion batteries (ZIBs) are considered promising next-generation energy storage devices, especially given their high potential for large-scale energy storage. Despite these advantages, many problems remain for ZIBs—such as Zn dendrite growth, hydrogen evolution, and Zn anode corrosion—which significantly reduce the coulomb efficiency and reversibility of the battery and limit its cycle lifespan, resulting in much uncertainty in terms of its practical applications. Numerous electrolyte additives have been proposed in recent years to solve the aforementioned problems. This review focuses on electrolyte additives and discusses the different substances employed as additives to overcome the problems by altering the Zn2+ solvation structure, creating a protective layer at the anode–electrolyte interface, and modulating the Zn2+ distribution to be even and Zn deposition to be uniform. On the basis of the review, the possible research strategies, future directions of electrolyte additive development, and the existing problems to be solved are also described.

Piezoelectric ultrasonic transducers have shown great potential in biomedical applications due to their high acoustic-to-electric conversion efficiency and large power capacity. The focusing technique enables the transducer to produce an extremely narrow beam, greatly improving the resolution and sensitivity. In this work, we summarize the fundamental properties and biological effects of the ultrasound field, aiming to establish a correlation between device design and application. Focusing techniques for piezoelectric transducers are highlighted, including material selection and fabrication methods, which determine the final performance of piezoelectric transducers. Numerous examples, from ultrasound imaging, neuromodulation, tumor ablation to ultrasonic wireless energy transfer, are summarized to highlight the great promise of biomedical applications. Finally, the challenges and opportunities of focused ultrasound transducers are presented. The aim of this review is to bridge the gap between focused ultrasound systems and biomedical applications.

Multimaterial (MM) 3D printing shows great potential for application in metamaterials, flexible electronics, biomedical devices and robots, since it can seamlessly integrate distinctive materials into one printed structure. Among numerous MM 3D printing technologies, digital light processing (DLP) MM 3D printing is compatible with a wide range of materials from hydrogels to ceramics, and can print MM 3D structures with high resolution, high complexity and fast speed. This paper introduces the fundamental mechanisms of DLP 3D printing, and reviews the recent advances of DLP MM 3D printing technologies with emphasis on material switching methods and material contamination issues. It also summarizes a number of typical examples of DLP MM 3D printing systems developed in the past decade, and introduces their system structures, working principles, material switching methods, residual resin removal methods, printing steps, as well as the representative structures and applications. Finally, we provide perspectives on the directions of the further development of DLP MM 3D printing technology.

Flexible electronics offer a multitude of advantages, such as flexibility, lightweight property, portability, and high durability. These unique properties allow for seamless applications to curved and soft surfaces, leading to extensive utilization across a wide range of fields in consumer electronics. These applications, for example, span integrated circuits, solar cells, batteries, wearable devices, bio-implants, soft robotics, and biomimetic applications. Recently, flexible electronic devices have been developed using a variety of materials such as organic, carbon-based, and inorganic semiconducting materials. Silicon (Si) owing to its mature fabrication process, excellent electrical, optical, thermal properties, and cost efficiency, remains a compelling material choice for flexible electronics. Consequently, the research on ultra-thin Si in the context of flexible electronics is studied rigorously nowadays. The thinning of Si is crucially important for flexible electronics as it reduces its bending stiffness and the resultant bending strain, thereby enhancing flexibility while preserving its exceptional properties. This review provides a comprehensive overview of the recent efforts in the fabrication techniques for forming ultra-thin Si using top-down and bottom-up approaches and explores their utilization in flexible electronics and their applications.

Over the course of millions of years, nature has evolved to ensure survival and presents us with a myriad of functional surfaces and structures that can boast high efficiency, multifunctionality, and sustainability. What makes these surfaces particularly practical and effective is the intricate micropatterning that enables selective interactions with microstructures. Most of these structures have been realized in the laboratory environment using numerous fabrication techniques by tailoring specific surface properties. Of the available manufacturing methods, additive manufacturing (AM) has created opportunities for fabricating these structures as the complex architectures of the naturally occurring microstructures far exceed the traditional ways. This paper presents a concise overview of the fundamentals of such patterned microstructured surfaces, their fabrication techniques, and diverse applications. A comprehensive evaluation of micro fabrication methods is conducted, delving into their respective strengths and limitations. Greater emphasis is placed on AM processes like inkjet printing and micro digital light projection printing due to the intrinsic advantages of these processes to additively fabricate high resolution structures with high fidelity and precision. The paper explores the various advancements in these processes in relation to their use in microfabrication and also presents the recent trends in applications like the fabrication of microlens arrays, microneedles, and tissue scaffolds.

Over millions of years of natural evolution, organisms have developed nearly perfect structures and functions. The self-fabrication of organisms serves as a valuable source of inspiration for designing the next-generation of structural materials, and is driving the future paradigm shift of modern materials science and engineering. However, the complex structures and multifunctional integrated optimization of organisms far exceed the capability of artificial design and fabrication technology, and new manufacturing methods are urgently needed to achieve efficient reproduction of biological functions. As one of the most valuable advanced manufacturing technologies of the 21st century, laser processing technology provides an efficient solution to the critical challenges of bionic manufacturing. This review outlines the processing principles, manufacturing strategies, potential applications, challenges, and future development outlook of laser processing in bionic manufacturing domains. Three primary manufacturing strategies for laser-based bionic manufacturing are elucidated: subtractive manufacturing, equivalent manufacturing, and additive manufacturing. The progress and trends in bionic subtractive manufacturing applied to micro/nano structural surfaces, bionic equivalent manufacturing for surface strengthening, and bionic additive manufacturing aiming to achieve bionic spatial structures, are reported. Finally, the key problems faced by laser-based bionic manufacturing, its limitations, and the development trends of its existing technologies are discussed.

Optical imaging systems have greatly extended human visual capabilities, enabling the observation and understanding of diverse phenomena. Imaging technologies span a broad spectrum of wavelengths from x-ray to radio frequencies and impact research activities and our daily lives. Traditional glass lenses are fabricated through a series of complex processes, while polymers offer versatility and ease of production. However, modern applications often require complex lens assemblies, driving the need for miniaturization and advanced designs with micro- and nanoscale features to surpass the capabilities of traditional fabrication methods. Three-dimensional (3D) printing, or additive manufacturing, presents a solution to these challenges with benefits of rapid prototyping, customized geometries, and efficient production, particularly suited for miniaturized optical imaging devices. Various 3D printing methods have demonstrated advantages over traditional counterparts, yet challenges remain in achieving nanoscale resolutions. Two-photon polymerization lithography (TPL), a nanoscale 3D printing technique, enables the fabrication of intricate structures beyond the optical diffraction limit via the nonlinear process of two-photon absorption within liquid resin. It offers unprecedented abilities, e.g. alignment-free fabrication, micro- and nanoscale capabilities, and rapid prototyping of almost arbitrary complex 3D nanostructures. In this review, we emphasize the importance of the criteria for optical performance evaluation of imaging devices, discuss material properties relevant to TPL, fabrication techniques, and highlight the application of TPL in optical imaging. As the first panoramic review on this topic, it will equip researchers with foundational knowledge and recent advancements of TPL for imaging optics, promoting a deeper understanding of the field. By leveraging on its high-resolution capability, extensive material range, and true 3D processing, alongside advances in materials, fabrication, and design, we envisage disruptive solutions to current challenges and a promising incorporation of TPL in future optical imaging applications.

Triboelectric materials with high charge density are the building-block for the commercial application of triboelectric nanogenerators (TENGs). Unstable dynamic processes influence the change of the charge density on the surface and inside of triboelectric materials. The charge density of triboelectric materials depends on the surface and the internal charge transfer processes. The focus of this review is on recent advances in high charge density triboelectric materials and advances in the fabrication of TENGs. We summarize the existing strategies for achieving high charge density in triboelectric materials as well as their fundamental properties. We then review current optimization methods for regulating dynamic charge transfer processes to increase the output charge density: first, increasing charge injection and limiting charge dissipation to achieve a high average surface charge density, and second, regulating the internal charge transfer process and storing charge in triboelectric materials to increase the output charge density. Finally, we present the challenges and prospects in developing high-performance triboelectric materials.

Multistable mechanical metamaterials are a type of mechanical metamaterials with special features, such as reusability, energy storage and absorption capabilities, rapid deformation, and amplified output forces. These metamaterials are usually realized by series and/or parallel of bistable units. They can exhibit multiple stable configurations under external loads and can be switched reversely among each other, thereby realizing the reusability of mechanical metamaterials and offering broad engineering applications. This paper reviews the latest research progress in the design strategy, manufacture and application of multistable mechanical metamaterials. We divide bistable structures into three categories based on their basic element types and provide the criterion of their bistability. Various manufacturing techniques to fabricate these multistable mechanical metamaterials are introduced, including mold casting, cutting, folding and three-dimensional/4D printing. Furthermore, the prospects of multistable mechanical metamaterials for applications in soft driving, mechanical computing, energy absorption and wave controlling are discussed. Finally, this paper highlights possible challenges and opportunities for future investigations. The review aims to provide insights into the research and development of multistable mechanical metamaterials.

Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment. Inspired by nature, researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate. Among many fabrication methods for stimulus-responsive structures, femtosecond laser direct writing (FsLDW) has received increasing attention because of its high precision, simplicity, true three-dimensional machining ability, and wide applicability to almost all materials. This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW. Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies, different stimulating factors that can trigger structural responses of prepared intelligent structures, such as magnetic field, light, temperature, pH, and humidity, are emphatically summarized. Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW, as well as the present obstacles and forthcoming development opportunities, are discussed.

Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality. However, a significant technical challenge in grinding is the potential increase in temperature due to high specific energy, which can lead to surface thermal damage. Therefore, ensuring control over the surface integrity of workpieces during grinding becomes a critical concern. This necessitates the development of temperature field models that consider various parameters, such as workpiece materials, grinding wheels, grinding parameters, cooling methods, and media, to guide industrial production. This study thoroughly analyzes and summarizes grinding temperature field models. First, the theory of the grinding temperature field is investigated, classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source, depending on whether the heat source is uniform and continuous. Through this examination, a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived. Subsequently, various grinding thermal models are summarized, including models for the heat source distribution, energy distribution proportional coefficient, and convective heat transfer coefficient. Through comprehensive research, the most widely recognized, utilized, and accurate model for each category is identified. The application of these grinding thermal models is reviewed, shedding light on the governing laws that dictate the influence of the heat source distribution, heat distribution, and convective heat transfer in the grinding arc zone on the grinding temperature field. Finally, considering the current issues in the field of grinding temperature, potential future research directions are proposed. The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity.

Neuromorphic computing is a brain-inspired computing paradigm that aims to construct efficient, low-power, and adaptive computing systems by emulating the information processing mechanisms of biological neural systems. At the core of neuromorphic computing are neuromorphic devices that mimic the functions and dynamics of neurons and synapses, enabling the hardware implementation of artificial neural networks. Various types of neuromorphic devices have been proposed based on different physical mechanisms such as resistive switching devices and electric-double-layer transistors. These devices have demonstrated a range of neuromorphic functions such as multistate storage, spike-timing-dependent plasticity, dynamic filtering, etc. To achieve high performance neuromorphic computing systems, it is essential to fabricate neuromorphic devices compatible with the complementary metal oxide semiconductor (CMOS) manufacturing process. This improves the device’s reliability and stability and is favorable for achieving neuromorphic chips with higher integration density and low power consumption. This review summarizes CMOS-compatible neuromorphic devices and discusses their emulation of synaptic and neuronal functions as well as their applications in neuromorphic perception and computing. We highlight challenges and opportunities for further development of CMOS-compatible neuromorphic devices and systems.

Magnesium and its alloys, as a promising class of materials, is popular in lightweight application and biomedical implants due to their low density and good biocompatibility. Additive manufacturing (AM) of Mg and its alloys is of growing interest in academia and industry. The domain-by-domain localized forming characteristics of AM leads to unique microstructures and performances of AM-process Mg and its alloys, which are different from those of traditionally manufactured counterparts. However, the intrinsic mechanisms still remain unclear and need to be in-depth explored. Therefore, this work aims to discuss and analyze the possible underlying mechanisms regarding defect appearance and elimination, microstructure formation and evolution, and performance improvement, based on presenting a comprehensive and systematic review on the relationship between process parameters, forming quality, microstructure characteristics and resultant performances. Lastly, some key perspectives requiring focus for further progression are highlighted to promote development of AM-processed Mg and its alloys and accelerate their industrialization.

Three-dimensional (3D) printing, an additive manufacturing technique, is widely employed for the fabrication of various electrochemical energy storage devices (EESDs), such as batteries and supercapacitors, ranging from nanoscale to macroscale. This technique offers excellent manufacturing flexibility, geometric designability, cost-effectiveness, and eco-friendliness. Recent studies have focused on the utilization of 3D-printed critical materials for EESDs, which have demonstrated remarkable electrochemical performances, including high energy densities and rate capabilities, attributed to improved ion/electron transport abilities and fast kinetics. However, there is a lack of comprehensive reviews summarizing and discussing the recent advancements in the structural design and application of 3D-printed critical materials for EESDs, particularly rechargeable batteries. In this review, we primarily concentrate on the current progress in 3D printing (3DP) critical materials for emerging batteries. We commence by outlining the key characteristics of major 3DP methods employed for fabricating EESDs, encompassing design principles, materials selection, and optimization strategies. Subsequently, we summarize the recent advancements in 3D-printed critical materials (anode, cathode, electrolyte, separator, and current collector) for secondary batteries, including conventional Li-ion (LIBs), Na-ion (SIBs), K-ion (KIBs) batteries, as well as Li/Na/K/Zn metal batteries, Zn-air batteries, and Ni–Fe batteries. Within these sections, we discuss the 3DP precursor, design principles of 3D structures, and working mechanisms of the electrodes. Finally, we address the major challenges and potential applications in the development of 3D-printed critical materials for rechargeable batteries.

Textile electronics have become an indispensable part of wearable applications because of their large flexibility, light-weight, comfort and electronic functionality upon the merge of textiles and microelectronics. As a result, the fabrication of functional fibrous materials and the integration of textile electronic devices have attracted increasing interest in the wearable electronic community. Challenges are encountered in the development of textile electronics in a way that is electrically reliable and durable, without compromising on the deformability and comfort of a garment, including processing multiple materials with great mismatches in mechanical, thermal, and electrical properties and assembling various structures with the disparity in dimensional scales and surface roughness. Equal challenges lie in high-quality and cost-effective processes facilitated by high-level digital technology enabled design and manufacturing methods. This work reviews the manufacturing of textile-shaped electronics via the processing of functional fibrous materials from the perspective of hierarchical architectures, and discusses the heterogeneous integration of microelectronics into normal textiles upon the fabric circuit board and adapted electrical connections, broadly covering both conventional and advanced textile electronic production processes. We summarize the applications and obstacles of textile electronics explored so far in sensors, actuators, thermal management, energy fields, and displays. Finally, the main conclusions and outlook are provided while the remaining challenges of the fabrication and application of textile electronics are emphasized.

Neuromorphic computing systems can perform memory and computing tasks in parallel on artificial synaptic devices through simulating synaptic functions, which is promising for breaking the conventional von Neumann bottlenecks at hardware level. Artificial optoelectronic synapses enable the synergistic coupling between optical and electrical signals in synaptic modulation, which opens up an innovative path for effective neuromorphic systems. With the advantages of high mobility, optical transparency, ultrawideband tunability, and environmental stability, graphene has attracted tremendous interest for electronic and optoelectronic applications. Recent progress highlights the significance of implementing graphene into artificial synaptic devices. Herein, to better understand the potential of graphene-based synaptic devices, the fabrication technologies of graphene are first presented. Then, the roles of graphene in various synaptic devices are demonstrated. Furthermore, their typical optoelectronic applications in neuromorphic systems are reviewed. Finally, outlooks for development of synaptic devices based on graphene are proposed. This review will provide a comprehensive understanding of graphene fabrication technologies and graphene-based synaptic device for optoelectronic applications, also present an outlook for development of graphene-based synaptic device in future neuromorphic systems.

The introduction of living cells to manufacturing process has enabled the engineering of complex biological tissues in vitro. The recent advances in biofabrication with extremely high resolution (e.g. at single cell level) have greatly enhanced this capacity and opened new avenues for tissue engineering. In this review, we comprehensively overview the current biofabrication strategies with single-cell resolution and categorize them based on the dimension of the single-cell building blocks, i.e. zero-dimensional single-cell droplets, one-dimensional single-cell filaments and two-dimensional single-cell sheets. We provide an informative introduction to the most recent advances in these approaches (e.g. cell trapping, bioprinting, electrospinning, microfluidics and cell sheets) and further illustrated how they can be used in in vitro tissue modelling and regenerative medicine. We highlight the significance of single-cell-level biofabrication and discuss the challenges and opportunities in the field.

Three-dimensional (3D) printing technology has opened a new paradigm to controllably and reproducibly fabricate bioengineered neural constructs for potential applications in repairing injured nervous tissues or producing in vitro nervous tissue models. However, the complexity of nervous tissues poses great challenges to 3D-printed bioengineered analogues, which should possess diverse architectural/chemical/electrical functionalities to resemble the native growth microenvironments for functional neural regeneration. In this work, we provide a state-of-the-art review of the latest development of 3D printing for bioengineered neural constructs. Various 3D printing techniques for neural tissue-engineered scaffolds or living cell-laden constructs are summarized and compared in terms of their unique advantages. We highlight the advanced strategies by integrating topographical, biochemical and electroactive cues inside 3D-printed neural constructs to replicate in vivo-like microenvironment for functional neural regeneration. The typical applications of 3D-printed bioengineered constructs for in vivo repair of injured nervous tissues, bio-electronics interfacing with native nervous system, neural-on-chips as well as brain-like tissue models are demonstrated. The challenges and future outlook associated with 3D printing for functional neural constructs in various categories are discussed.

Auxetic mechanical metamaterials are artificially architected materials that possess negative Poisson’s ratio, demonstrating transversal contracting deformation under external vertical compression loading. Their physical properties are mainly determined by spatial topological configurations. Traditionally, classical auxetic mechanical metamaterials exhibit relatively lower mechanical stiffness, compared to classic stretching dominated architectures. Nevertheless, in recent years, several novel auxetic mechanical metamaterials with high stiffness have been designed and proposed for energy absorption, load-bearing, and thermal-mechanical coupling applications. In this paper, mechanical design methods for designing auxetic structures with soft and stiff mechanical behavior are summarized and classified. For soft auxetic mechanical metamaterials, classic methods, such as using soft basic material, hierarchical design, tensile braided design, and curved ribs, are proposed. In comparison, for stiff auxetic mechanical metamaterials, design schemes, such as hard base material, hierarchical design, composite design, and adding additional load-bearing ribs, are proposed. Multi-functional applications of soft and stiff auxetic mechanical metamaterials are then reviewed. We hope this study could provide some guidelines for designing programmed auxetics with specified mechanical stiffness and deformation abilities according to demand.

Tribotronics is an emerging research field that focuses on the coupling of triboelectricity and semiconductors. In this review, we summarise and explore three branches of tribotronics. Firstly, we introduce the tribovoltaic effect, which involves direct-current power generation through mechanical friction on semiconductor interfaces. This effect offers significant advantages in terms of high power density compared to traditional insulator-based triboelectric nanogenerators. Secondly, we elaborate on triboelectric modulation, which utilises the triboelectric potential on field-effect transistors. This approach enables active mechanosensation and nanoscale tactile perception. Additionally, we present triboelectric management, which aims to improve energy supply efficiency using semiconductor device technology. This strategy provides an effective microenergy solution for sensors and microsystems. For the interactions between triboelectricity and semiconductors, the research of tribotronics has exhibited the electronics of interfacial friction systems, and the triboelectric technology by electronics. This review demonstrates the promising prospects of tribotronics in the development of new functional devices and self-powered microsystems for intelligent manufacturing, robotic sensing, and the industrial Internet of Things.

As Moore’s law deteriorates, the research and development of new materials system are crucial for transitioning into the post Moore era. Traditional semiconductor materials, such as silicon, have served as the cornerstone of modern technologies for over half a century. This has been due to extensive research and engineering on new techniques to continuously enrich silicon-based materials system and, subsequently, to develop better performed silicon-based devices. Meanwhile, in the emerging post Moore era, layered semiconductor materials, such as transition metal dichalcogenides (TMDs), have garnered considerable research interest due to their unique electronic and optoelectronic properties, which hold great promise for powering the new era of next generation electronics. As a result, techniques for engineering the properties of layered semiconductors have expanded the possibilities of layered semiconductor-based devices. However, there remain significant limitations in the synthesis and engineering of layered semiconductors, impeding the utilization of layered semiconductor-based devices for mass applications. As a practical alternative, heterogeneous integration between layered and traditional semiconductors provides valuable opportunities to combine the distinctive properties of layered semiconductors with well-developed traditional semiconductors materials system. Here, we provide an overview of the comparative coherence between layered and traditional semiconductors, starting with TMDs as the representation of layered semiconductors. We highlight the meaningful opportunities presented by the heterogeneous integration of layered semiconductors with traditional semiconductors, representing an optimal strategy poised to propel the emerging semiconductor research community and chip industry towards unprecedented advancements in the coming decades.

Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance; their appreciable mechanical, corrosive, and biocompatible properties are highly sought after for lightweight and high-strength load-bearing orthopedic and dental implants. Examples of such porous materials are metals, ceramics, and polymers. Although, easy to manufacture and lightweight, porous polymers do not inherently exhibit the required mechanical strength for hard tissue repair or replacement. Alternatively, porous ceramics are brittle and do not possess the required fatigue resistance. On the other hand, porous biocompatible metals have shown tailorable strength, fatigue resistance, and toughness. Thereby, a significant interest in investigating the manufacturing challenges of porous metals has taken place in recent years. Past research has shown that once the advantages of porous metallic structures in the orthopedic implant industry have been realized, their biological and biomechanical compatibility—with the host bone—has been followed up with extensive methodical research. Various manufacturing methods for porous or functionally graded metals are discussed and compared in this review, specifically, how the manufacturing process influences microstructure, graded composition, porosity, biocompatibility, and mechanical properties. Most of the studies discussed in this review are related to porous structures for bone implant applications; however, the understanding of these investigations may also be extended to other devices beyond the biomedical field.

Nanomaterial-based flexible sensors (NMFSs) can be tightly attached to the human skin or integrated with clothing to monitor human physiological information, provide medical data, or explore metaverse spaces. Nanomaterials have been widely incorporated into flexible sensors due to their facile processing, material compatibility, and unique properties. This review highlights the recent advancements in NMFSs involving various nanomaterial frameworks such as nanoparticles, nanowires, and nanofilms. Different triggering interaction interfaces between NMFSs and metaverse/virtual reality (VR) applications, e.g. skin-mechanics-triggered, temperature-triggered, magnetically triggered, and neural-triggered interfaces, are discussed. In the context of interfacing physical and virtual worlds, machine learning (ML) has emerged as a promising tool for processing sensor data for controlling avatars in metaverse/VR worlds, and many ML algorithms have been proposed for virtual interaction technologies. This paper discusses the advantages, disadvantages, and prospects of NMFSs in metaverse/VR applications.

As a new generation of materials/structures, heterostructure is characterized by heterogeneous zones with dramatically different mechanical, physical or chemical properties. This endows heterostructure with unique interfaces, robust architectures, and synergistic effects, making it a promising option as advanced biomaterials for the highly variable anatomy and complex functionalities of individual patients. However, the main challenges of developing heterostructure lie in the control of crystal/phase evolution and the distribution/fraction of components and structures. In recent years, additive manufacturing techniques have attracted increasing attention in developing heterostructure due to the unique flexibility in tailored structures and synthetic multimaterials. This review focuses on the additive manufacturing of heterostructure for biomedical applications. The structural features and functional mechanisms of heterostructure are summarized. The typical material systems of heterostructure, mainly including metals, polymers, ceramics, and their composites, are presented. And the resulting synergistic effects on multiple properties are also systematically discussed in terms of mechanical, biocompatible, biodegradable, antibacterial, biosensitive and magnetostrictive properties. Next, this work outlines the research progress of additive manufacturing employed in developing heterostructure from the aspects of advantages, processes, properties, and applications. This review also highlights the prospective utilization of heterostructure in biomedical fields, with particular attention to bioscaffolds, vasculatures, biosensors and biodetections. Finally, future research directions and breakthroughs of heterostructure are prospected with focus on their more prospective applications in infection prevention and drug delivery.

Four-dimensional printing allows for the transformation capabilities of 3D-printed architectures over time, altering their shape, properties, or function when exposed to external stimuli. This interdisciplinary technology endows the 3D architectures with unique functionalities, which has generated excitement in diverse research fields, such as soft robotics, biomimetics, biomedical devices, and sensors. Understanding the selection of the material, architectural designs, and employed stimuli is crucial to unlocking the potential of smart customization with 4D printing. This review summarizes recent significant developments in 4D printing and establishes links between smart materials, 3D printing techniques, programmable structures, diversiform stimulus, and new functionalities for multidisciplinary applications. We start by introducing the advanced features of 4D printing and the key technological roadmap for its implementation. We then place considerable emphasis on printable smart materials and structural designs, as well as general approaches to designing programmable structures. We also review stimulus designs in smart materials and their associated stimulus-responsive mechanisms. Finally, we discuss new functionalities of 4D printing for potential applications and further development directions.

Honglei Xue, Wanshuo Gao, Jianwei Gao, Grégory F Schneider, Chen Wang and Wangyang Fu

The continual demand for modern optoelectronics with a high integration degree and customized functions has increased requirements for nanofabrication methods with high resolution, freeform, and mask-free. Meniscus-on-demand three-dimensional (3D) printing is a high-resolution additive manufacturing technique that exploits the ink meniscus formed on a printer nozzle and is suitable for the fabrication of micro/nanoscale 3D architectures. This method can be used for solution-processed 3D patterning of materials at a resolution of up to 100 nm, which provides an excellent platform for fundamental scientific studies and various practical applications. This review presents recent advances in meniscus-on-demand 3D printing, together with historical perspectives and theoretical background on meniscus formation and stability. Moreover, this review highlights the capabilities of meniscus-on-demand 3D printing in terms of printable materials and potential areas of application, such as electronics and photonics.

Because of the complex nerve anatomy and limited regeneration ability of natural tissue, the current treatment effect for long-distance peripheral nerve regeneration and spinal cord injury (SCI) repair is not satisfactory. As an alternative method, tissue engineering is a promising method to regenerate peripheral nerve and spinal cord, and can provide structures and functions similar to natural tissues through scaffold materials and seed cells. Recently, the rapid development of 3D printing technology enables researchers to create novel 3D constructs with sophisticated structures and diverse functions to achieve high bionics of structures and functions. In this review, we first outlined the anatomy of peripheral nerve and spinal cord, as well as the current treatment strategies for the peripheral nerve injury and SCI in clinical. After that, the design considerations of peripheral nerve and spinal cord tissue engineering were discussed, and various 3D printing technologies applicable to neural tissue engineering were elaborated, including inkjet, extrusion-based, stereolithography, projection-based, and emerging printing technologies. Finally, we focused on the application of 3D printing technology in peripheral nerve regeneration and spinal cord repair, as well as the challenges and prospects in this research field.

Piezoelectricity in native bones has been well recognized as the key factor in bone regeneration. Thus, bio-piezoelectric materials have gained substantial attention in repairing damaged bone by mimicking the tissue’s electrical microenvironment (EM). However, traditional manufacturing strategies still encounter limitations in creating personalized bio-piezoelectric scaffolds, hindering their clinical applications. Three-dimensional (3D)/four-dimensional (4D) printing technology based on the principle of layer-by-layer forming and stacking of discrete materials has demonstrated outstanding advantages in fabricating bio-piezoelectric scaffolds in a more complex-shaped structure. Notably, 4D printing functionality-shifting bio-piezoelectric scaffolds can provide a time-dependent programmable tissue EM in response to external stimuli for bone regeneration. In this review, we first summarize the physicochemical properties of commonly used bio-piezoelectric materials (including polymers, ceramics, and their composites) and representative biological findings for bone regeneration. Then, we discuss the latest research advances in the 3D printing of bio-piezoelectric scaffolds in terms of feedstock selection, printing process, induction strategies, and potential applications. Besides, some related challenges such as feedstock scalability, printing resolution, stress-to-polarization conversion efficiency, and non-invasive induction ability after implantation have been put forward. Finally, we highlight the potential of shape/property/functionality-shifting smart 4D bio-piezoelectric scaffolds in bone tissue engineering (BTE). Taken together, this review emphasizes the appealing utility of 3D/4D printed biological piezoelectric scaffolds as next-generation BTE implants.

Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties, thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity. This greatly expands the applications of copper as a functional material in thermal and conductive components, including electronic packaging materials and heat sinks, brushes, integrated circuit lead frames. So far, endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix. This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles, including ceramic particle content, size, morphology and interfacial bonding, on the diathermancy, electrical conductivity and mechanical behavior of copper matrix composites. The corresponding models and influencing mechanisms are also elaborated in depth. This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites. By more precise design and manipulation of composite microstructure, the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields.

Flexible and stretchable transparent electrodes are widely used in smart display, energy, wearable devices and other fields. Due to the limitations of flexibility and stretchability of indium tin oxide electrodes, alternative electrodes have appeared, such as metal films, metal nanowires, and conductive meshes. However, few of the above electrodes can simultaneously have excellent flexibility, stretchability, and optoelectronic properties. Nanofiber (NF), a continuous ultra-long one-dimensional conductive material, is considered to be one of the ideal materials for high-performance transparent electrodes with excellent properties due to its unique structure. This paper summarizes the important research progress of NF flexible transparent electrodes (FTEs) in recent years from the aspects of NF electrode materials, preparation technology and application. First, the unique advantages and limitations of various NF materials are systematically discussed. Then, we summarize the preparation technology of various advanced NF FTEs, and point out the future development trend. We also discuss the application of NFs in solar cells, supercapacitors, electric heating equipments, sensors, etc, and analyze its development potential in flexible electronic equipment, as well as problems that need to be solved. Finally, the challenges and future development trends are proposed in the wide application of NF FTEs in the field of flexible optoelectronics.

Articular cartilage damage caused by trauma or degenerative pathologies such as osteoarthritis can result in significant pain, mobility issues, and disability. Current surgical treatments have a limited capacity for efficacious cartilage repair, and long-term patient outcomes are not satisfying. Three-dimensional bioprinting has been used to fabricate biochemical and biophysical environments that aim to recapitulate the native microenvironment and promote tissue regeneration. However, conventional in vitro bioprinting has limitations due to the challenges associated with the fabrication and implantation of bioprinted constructs and their integration with the native cartilage tissue. In situ bioprinting is a novel strategy to directly deliver bioinks to the desired anatomical site and has the potential to overcome major shortcomings associated with conventional bioprinting. In this review, we focus on the new frontier of robotic-assisted in situ bioprinting surgical systems for cartilage regeneration. We outline existing clinical approaches and the utilization of robotic-assisted surgical systems. Handheld and robotic-assisted in situ bioprinting techniques including minimally invasive and non-invasive approaches are defined and presented. Finally, we discuss the challenges and potential future perspectives of in situ bioprinting for cartilage applications.

Atomic layer deposition (ALD) has become an indispensable thin-film technology in the contemporary microelectronics industry. The unique self-limited layer-by-layer growth feature of ALD has outstood this technology to deposit highly uniform conformal pinhole-free thin films with angstrom-level thickness control, particularly on 3D topologies. Over the years, the ALD technology has enabled not only the successful downscaling of the microelectronic devices but also numerous novel 3D device structures. As ALD is essentially a variant of chemical vapor deposition, a comprehensive understanding of the involved chemistry is of crucial importance to further develop and utilize this technology. To this end, we, in this review, focus on the surface chemistry and precursor chemistry aspects of ALD. We first review the surface chemistry of the gas–solid ALD reactions and elaborately discuss the associated mechanisms for the film growth; then, we review the ALD precursor chemistry by comparatively discussing the precursors that have been commonly used in the ALD processes; and finally, we selectively present a few newly-emerged applications of ALD in microelectronics, followed by our perspective on the future of the ALD technology.

The exceptional physical properties and unique layered structure of two-dimensional (2D) materials have made this class of materials great candidates for applications in electronics, energy conversion/storage devices, nanocomposites, and multifunctional coatings, among others. At the center of this application space, mechanical properties play a vital role in materials design, manufacturing, integration and performance. The emergence of 2D materials has also sparked broad scientific inquiry, with new understanding of mechanical interactions between 2D structures and interfaces being of great interest to the community. Building on the dramatic expansion of recent research activities, here we review significant advances in the understanding of the elastic properties, in-plane failures, fatigue performance, interfacial shear/friction, and adhesion behavior of 2D materials. In this article, special emphasis is placed on some new 2D materials, novel characterization techniques and computational methods, as well as insights into deformation and failure mechanisms. A deep understanding of the intrinsic and extrinsic factors that govern 2D material mechanics is further provided, in the hopes that the community may draw design strategies for structural and interfacial engineering of 2D material systems. We end this review article with a discussion of our perspective on the state of the field and outlook on areas for future research directions.

NiTi alloys have drawn significant attentions in biomedical and aerospace fields due to their unique shape memory effect (SME), superelasticity (SE), damping characteristics, high corrosion resistance, and good biocompatibility. Because of the unsatisfying processabilities and manufacturing requirements of complex NiTi components, additive manufacturing technology, especially laser powder bed fusion (LPBF), is appropriate for fabricating NiTi products. This paper comprehensively summarizes recent research on the NiTi alloys fabricated by LPBF, including printability, microstructural characteristics, phase transformation behaviors, lattice structures, and applications. Process parameters and microstructural features mainly influence the printability of LPBF-processed NiTi alloys. The phase transformation behaviors between austenite and martensite phases, phase transformation temperatures, and an overview of the influencing factors are summarized in this paper. This paper provides a comprehensive review of the mechanical properties with unique strain-stress responses, which comprise tensile mechanical properties, thermomechanical properties (e.g. critical stress to induce martensitic transformation, thermo-recoverable strain, and SE strain), damping properties and hardness. Moreover, several common structures (e.g. a negative Poisson’s ratio structure and a diamond-like structure) are considered, and the corresponding studies are summarized. It illustrates the various fields of application, including biological scaffolds, shock absorbers, and driving devices. In the end, the paper concludes with the main achievements from the recent studies and puts forward the limitations and development tendencies in the future.

Atomic layer deposition (ALD) is a versatile technique to deposit metals and metal oxide sensing materials at the atomic scale to achieve improved sensor functions. This article reviews metals and metal oxide semiconductor (MOS) heterostructures for gas sensing applications in which at least one of the preparation steps is carried out by ALD. In particular, three types of MOS-based heterostructures synthesized by ALD are discussed, including ALD of metal catalysts on MOS, ALD of metal oxides on MOS and MOS core–shell (C–S) heterostructures. The gas sensing performances of these heterostructures are carefully analyzed and discussed. Finally, the further developments required and the challenges faced by ALD for the synthesis of MOS gas sensing materials are discussed.

Van der Waals heterostructures (vdWHs) are showing considerable potential in both fundamental exploration and practical applications. Built upon the synthetic successes of (two-dimensional) 2D materials, several synthetic strategies of vdWHs have been developed, allowing the convenient fabrication of diverse vdWHs with decent controllability, quality, and scalability. This review first summarizes the current state of the art in synthetic strategies of vdWHs, including physical combination, deposition, solvothermal synthesis, and synchronous evolution. Then three major applications and their representative vdWH devices have been reviewed, including electronics (tunneling field effect transistors and 2D contact), optoelectronics (photodetector), and energy conversion (electrocatalysts and metal ion batteries), to unveil the potentials of vdWHs in practical applications and provide the general design principles of functional vdWHs for different applications. Besides, moiré superlattices based on vdWHs are discussed to showcase the importance of vdWHs as a platform for novel condensed matter physics. Finally, the crucial challenges towards ideal vdWHs with high performance are discussed, and the outlook for future development is presented. By the systematical integration of synthetic strategies and applications, we hope this review can further light up the rational designs of vdWHs for emerging applications.

Parts with high-quality freeform surfaces have been widely used in industries, which require strict quality control during the manufacturing process. Among all the industrial inspection methods, contact measurement with coordinate measuring machines or computer numerical control machine tool is a fundamental technique due to its high accuracy, robustness, and universality. In this paper, the existing research in the contact measurement field is systematically reviewed. First, different configurations of the measuring machines are introduced in detail, which may have influence on the corresponding sampling and inspection path generation criteria. Then, the entire inspection pipeline is divided into two stages, namely the pre-inspection and post-inspection stages. The typical methods of each sub-stage are systematically overviewed and classified, including sampling, accessibility analysis, inspection path generation, probe tip radius compensation, surface reconstruction, and uncertainty analysis. Apart from those classical research, the applications of the emerging deep learning technique in some specific tasks of measurement are introduced. Furthermore, some potential and promising trends are provided for future investigation.

Zero-emission eco-friendly vehicles with partly or fully electric powertrains have exhibited rapidly increased demand for reducing the emissions of air pollutants and improving the energy efficiency. Advanced catalytic and energy materials are essential as the significant portions in the key technologies of eco-friendly vehicles, such as the exhaust emission control system, power lithium ion battery and hydrogen fuel cell. Precise synthesis and surface modification of the functional materials and electrodes are required to satisfy the efficient surface and interface catalysis, as well as rapid electron/ion transport. Atomic layer deposition (ALD), an atomic and close-to-atomic scale manufacturing method, shows unique characteristics of precise thickness control, uniformity and conformality for film deposition, which has emerged as an important technique to design and engineer advanced catalytic and energy materials. This review has summarized recent process of ALD on the controllable preparation and modification of metal and oxide catalysts, as well as lithium ion battery and fuel cell electrodes. The enhanced catalytic and electrochemical performances are discussed with the unique nanostructures prepared by ALD. Recent works on ALD reactors for mass production are highlighted. The challenges involved in the research and development of ALD on the future practical applications are presented, including precursor and deposition process investigation, practical device performance evaluation, large-scale and efficient production, etc.

Tribology at cryogenic temperatures has attracted much attention since the 1950s with the acceleration of its applications in high-tech equipment such as cryogenic wind tunnels, liquid fuel rockets, space infrared telescopes, superconducting devices, and planetary exploration, which require solid lubrication for moving parts at low temperatures down to 4 K in cryogenic liquid, gaseous, or vacuum environments. Herein, the research progress regarding cryo-tribology is reviewed. The tribological properties and mechanisms of solid lubricants listed as carbon materials, molybdenum disulfide, polymers, and polymer-based composites with decreasing temperature are summarized. The friction coefficient increases with decreasing temperature induced by thermally activated processes. The mechanism of transfer film formation should be considered as a significant way to enhance the tribological properties of solid lubricants. In addition, applications of solid lubrication on moving parts under cryogenic conditions, such as spherical plain bearings and roller bearings, are introduced. The technology for tribological testing of materials and bearings at cryogenic temperatures is summarized, where the environmental control, motion and loading realization, as well as friction and wear measurement together in a low-temperature environment, result in the difficulties and challenges of the low-temperature tribotester. In particular, novel technologies and tribotesters have been developed for tribotests and tribological studies of solid lubricants, spherical plain bearings, and roller bearings, overcoming limitations regarding cooling in vacuum and resolution of friction measurement, among others, and concentrating on in-situ observation of friction interface. These not only promote a deep understanding of friction and wear mechanism at low temperatures, but also provide insights into the performance of moving parts or components in cryogenic applications.

High-speed machining (HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However, the underlying mechanisms of HSM have not been formally reviewed thus far. This article focuses on the solid mechanics framework of adiabatic shear band (ASB) onset and material metallurgical microstructural evolutions in HSM. The ASB onset is described using partial differential systems. Several factors in HSM were considered in the systems, and the ASB onset conditions were obtained by solving these systems or applying the perturbation method to the systems. With increasing machining speed, an ASB can be depressed and further eliminated by shock pressure. The damage observed in HSM exhibits common features. Equiaxed fine grains produced by dynamic recrystallization widely cause damage to ductile materials, and amorphization is the common microstructural evolution in brittle materials. Based on previous studies, potential mechanisms for the phenomena in HSM are proposed. These include the thickness variation of the white layer of ductile materials. These proposed mechanisms would be beneficial to deeply understanding the various phenomena in HSM.

The concept of multi-principal component has created promising opportunities for the development of novel high-entropy ceramics for extreme environments encountered in advanced turbine engines, nuclear reactors, and hypersonic vehicles, as it expands the compositional space of ceramic materials with tailored properties within a single-phase solid solution. The unique physical properties of some high-entropy carbides and borides, such as higher hardness, high-temperature strength, lower thermal conductivity, and improved irradiation resistance than the constitute ceramics, have been observed. These promising properties may be attributed to the compositional complexity, atomic-level disorder, lattice distortion, and other fundamental processes related to defect formation and phonon scattering. This manuscript serves as a critical review of the recent progress in high-entropy carbides and borides, focusing on synthesis and evaluations of their performance in extreme high-temperature, irradiation, and gaseous environments.

Ultra-precision diamond cutting is a promising machining technique for realizing ultra-smooth surface of different kinds of materials. While fundamental understanding of the impact of workpiece material properties on cutting mechanisms is crucial for promoting the capability of the machining technique, numerical simulation methods at different length and time scales act as important supplements to experimental investigations. In this work, we present a compact review on recent advancements in the numerical simulations of material-oriented diamond cutting, in which representative machining phenomena are systematically summarized and discussed by multiscale simulations such as molecular dynamics simulation and finite element simulation: the anisotropy cutting behavior of polycrystalline material, the thermo-mechanical coupling tool-chip friction states, the synergetic cutting responses of individual phase in composite materials, and the impact of various external energetic fields on cutting processes. In particular, the novel physics-based numerical models, which involve the high precision constitutive law associated with heterogeneous deformation behavior, the thermo-mechanical coupling algorithm associated with tool-chip friction, the configurations of individual phases in line with real microstructural characteristics of composite materials, and the integration of external energetic fields into cutting models, are highlighted. Finally, insights into the future development of advanced numerical simulation techniques for diamond cutting of advanced structured materials are also provided. The aspects reported in this review present guidelines for the numerical simulations of ultra-precision mechanical machining responses for a variety of materials.

Since the first report of amorphous In–Ga–Zn–O based thin film transistors, interest in oxide semiconductors has grown. They offer high mobility, low off-current, low process temperature, and wide flexibility for compositions and processes. Unfortunately, depositing oxide semiconductors using conventional processes like physical vapor deposition leads to problematic issues, especially for high-resolution displays and highly integrated memory devices. Conventional approaches have limited process flexibility and poor conformality on structured surfaces. Atomic layer deposition (ALD) is an advanced technique which can provide conformal, thickness-controlled, and high-quality thin film deposition. Accordingly, studies on ALD based oxide semiconductors have dramatically increased recently. Even so, the relationships between the film properties of ALD-oxide semiconductors and the main variables associated with deposition are still poorly understood, as are many issues related to applications. In this review, to introduce ALD-oxide semiconductors, we provide: (a) a brief summary of the history and importance of ALD-based oxide semiconductors in industry, (b) a discussion of the benefits of ALD for oxide semiconductor deposition (in-situ composition control in vertical distribution/vertical structure engineering/chemical reaction and film properties/insulator and interface engineering), and (c) an explanation of the challenging issues of scaling oxide semiconductors and ALD for industrial applications. This review provides valuable perspectives for researchers who have interest in semiconductor materials and electronic device applications, and the reasons ALD is important to applications of oxide semiconductors.

With the rapid development in advanced industries, such as microelectronics and optics sectors, the functional feature size of devises/components has been decreasing from micro to nanometric, and even ACS for higher performance, smaller volume and lower energy consumption. By this time, a great many quantum structures are proposed, with not only an extreme scale of several or even single atom, but also a nearly ideal lattice structure with no material defect. It is almost no doubt that such structures play critical role in the next generation products, which shows an urgent demand for the ACSM. Laser machining is one of the most important approaches widely used in engineering and scientific research. It is high-efficient and applicable for most kinds of materials. Moreover, the processing scale covers a huge range from millimeters to nanometers, and has already touched the atomic level. Laser–material interaction mechanism, as the foundation of laser machining, determines the machining accuracy and surface quality. It becomes much more sophisticated and dominant with a decrease in processing scale, which is systematically reviewed in this article. In general, the mechanisms of laser-induced material removal are classified into ablation, CE and atomic desorption, with a decrease in the scale from above microns to angstroms. The effects of processing parameters on both fundamental material response and machined surface quality are discussed, as well as theoretical methods to simulate and understand the underlying mechanisms. Examples at nanometric to atomic scale are provided, which demonstrate the capability of laser machining in achieving the ultimate precision and becoming a promising approach to ACSM.

Two-dimensional (2D)/quasi-2D organic-inorganic halide perovskites are regarded as naturally formed multiple quantum wells with inorganic layers isolated by long organic chains, which exhibit layered structure, large exciton binding energy, strong nonlinear optical effect, tunable bandgap via changing the layer number or chemical composition, improved environmental stability, and excellent optoelectronic properties. The extensive choice of long organic chains endows 2D/quasi-2D perovskites with tunable electron-phonon coupling strength, chirality, or ferroelectricity properties. In particular, the layered nature of 2D/quasi-2D perovskites allows us to exfoliate them to thin plates to integrate with other materials to form heterostructures, the fundamental structural units for optoelectronic devices, which would greatly extend the functionalities in view of the diversity of 2D/quasi-2D perovskites. In this paper, the recent achievements of 2D/quasi-2D perovskite-based heterostructures are reviewed. First, the structure and physical properties of 2D/quasi-2D perovskites are introduced. We then discuss the construction and characterizations of 2D/quasi-2D perovskite-based heterostructures and highlight the prominent optical properties of the constructed heterostructures. Further, the potential applications of 2D/quasi-2D perovskite-based heterostructures in photovoltaic devices, light emitting devices, photodetectors/phototransistors, and valleytronic devices are demonstrated. Finally, we summarize the current challenges and propose further research directions in the field of 2D/quasi-2D perovskite-based heterostructures.

Brittle materials are widely used for producing important components in the industry of optics, optoelectronics, and semiconductors. Ultraprecision machining of brittle materials with high surface quality and surface integrity helps improve the functional performance and lifespan of the components. According to their hardness, brittle materials can be roughly divided into hard-brittle and soft-brittle. Although there have been some literature reviews for ultraprecision machining of hard-brittle materials, up to date, very few review papers are available that focus on the processing of soft-brittle materials. Due to the ‘soft’ and ‘brittle’ properties, this group of materials has unique machining characteristics. This paper presents a comprehensive overview of recent advances in ultraprecision machining of soft-brittle materials. Critical aspects of machining mechanisms, such as chip formation, surface topography, and subsurface damage for different machining methods, including diamond turning, micro end milling, ultraprecision grinding, and micro/nano burnishing, are compared in terms of tool-workpiece interaction. The effects of tool geometries on the machining characteristics of soft-brittle materials are systematically analyzed, and dominating factors are sorted out. Problems and challenges in the engineering applications are identified, and solutions/guidelines for future R&D are provided.

Material removal in the cutting process is regarded as a friction system with multiple input and output variables. The complexity of the cutting friction system is caused by the extreme conditions existing on the tool–chip and tool–workpiece interfaces. The critical issue is significant to use knowledge of cutting friction behaviors to guide researchers and industrial manufacturing engineers in designing rational cutting processes to reduce tool wear and improve surface quality. This review focuses on the state of the art of research on friction behaviors in cutting procedures as well as future perspectives. First, the cutting friction phenomena under extreme conditions, such as high temperature, large strain/strain rates, sticking–sliding contact states, and diverse cutting conditions are analyzed. Second, the theoretical models of cutting friction behaviors and the application of simulation technology are discussed. Third, the factors that affect friction behaviors are analyzed, including material matching, cutting parameters, lubrication/cooling conditions, micro/nano surface textures, and tool coatings. Then, the consequences of the cutting friction phenomena, including tool wear patterns, tool life, chip formation, and the machined surface are analyzed. Finally, the research limitations and future work for cutting friction behaviors are discussed. This review contributes to the understanding of cutting friction behaviors and the development of high-quality cutting technology.

To move the performance of lithium-ion batteries into the next stage, the modification of the structure of cells is the only choice except for the development of materials exhibiting higher performance. In this review paper, the employment of through-holing structures of anodes and cathodes prepared with a picosecond pulsed laser has been proposed. The laser system and the structure for improving the battery performance were introduced. The performance of laminated cells constructed with through-holed anodes and cathodes was reviewed from the viewpoints of the improvement of high-rate performance and energy density, removal of unbalanced capacities on both sides of the current collector, even greater high-rate performance by hybridizing cathode materials and removal of irreversible capacity. In conclusion, the points that should be examined and the problem for the through-holed structure to be in practical use are summarized.

Inorganic-based micro light-emitting diodes (microLEDs) offer more fascinating properties and unique demands in next-generation displays. However, the small size of the microLED chip (1-100 μm) makes it extremely challenging for high efficiency and low cost to accurately, selectively, integrate millions of microLED chips. Recent impressive technological advances have overcome the drawbacks of traditional pick-and-place techniques when they were utilized in the assembly of microLED display, including the most broadly recognized laser lift-off technique, contact micro-transfer printing (μTP) technique, laser non-contact μTP technique, and self-assembly technique. Herein, we firstly review the key developments in mass transfer technique and highlight their potential value, covering both the state-of-the-art devices and requirements for mass transfer in the assembly of the ultra-large-area display and virtual reality glasses. We begin with the significant challenges and the brief history of mass transfer technique, and expand that mass transfer technique is composed of two major techniques, namely, the epitaxial Lift-off technique and the pick-and-place technique. The basic concept and transfer effects for each representative epitaxial Lift-off and pick-and-place technique in mass transfer are then overviewed separately. Finally, the potential challenges and future research directions of mass transfer are discussed.

Polymers are widely used materials in aerospace, automotive, construction, medical devices and pharmaceuticals. Polymers are being promoted rapidly due to their ease of manufacturing and improved material properties. Research on polymer processing technology should be paid more attention to due to the increasing demand for polymer applications. Selective laser sintering (SLS) uses a laser to sinter powdered materials (typical polyamide), and it is one of the critical additive manufacturing (AM) techniques of polymer. It irradiates the laser beam on the defined areas by a computer-aided design three-dimensional (3D) model to bind the material together to create a designed 3D solid structure. SLS has many advantages, such as no support structures and excellent mechanical properties resembling injection moulded parts compared with other AM methods. However, the ability of SLS to process polymers is still affected by some defects, such as the porous structure and limited available types of SLS polymers. Therefore, this article reviews the current state-of-the-art SLS of polymers, including the fundamental principles in this technique, the SLS developments of typical polymers, and the essential process parameters in SLS. Furthermore, the applications of SLS are focused, and the conclusions and perspectives are discussed.

Carbon dots (CDs), as a unique zero-dimensional member of carbon materials, have attracted numerous attentions for their potential applications in optoelectronic, biological, and energy related fields. Recently, CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization, fast migration of charge carriers, efficient surface redox reactions and good electrical conductivity. In this review, we summarize the fabrication methods of CDs and corresponding CD nanocomposites, including the strategies of surface modification and heteroatom doping. The properties of CDs that concerned to the photo- and electro-catalysis are highlighted and detailed corresponding applications are listed. More importantly, as new non-contact detection technologies, transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics, which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts. The development and application of the techniques are reviewed. Finally, we discuss and outline the major challenges and opportunities for future CD-based catalysts, and the needs and expectations for the development of novel characterization technologies.

Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thinking, and observing power of existing humans. Imaginations related to space explorations, portability, accessibility have also witnessed sensible in today’s time with freeform optics. Present-day design methods and fabrications techniques applicable in the development of freeform optics and the market requirements are focussed and explained with the help of traditional and non-traditional optical applications. Over the years, significant research is performed in the emerging field of freeform optics, but no standards are established yet in terms of tolerances and definitions. We critically review the optical design methods for freeform optics considering the image forming and non-image forming applications. Numerous subtractive manufacturing technologies including figure correction methods and metrology have been developed to fabricate extreme modern freeform optics to satisfy the demands of various applications such as space, astronomy, earth science, defence, biomedical, material processing, surveillance, and many more. We described a variety of advanced technologies in manufacturing and metrology for novel freeform optics. Next, we also covered the manufacturing-oriented design scheme for advanced optics. We conclude this review with an outlook on the future of freeform optics design, manufacturing and metrology.

Dispersing atomic metals on substrates provides an ideal method to maximize metal utilization efficiency, which is important for the production of cost-effective catalysts and the atomic-level control of the electronic structure. However, due to the high surface energy, individual single atoms tend to migrate and aggregate into nanoparticles during preparation and catalytic operation. In the past few years, various synthetic strategies based on ultrafast thermal activation toward the effective preparation of single-atom catalysts (SACs) have emerged, which could effectively solve the aggregation issue. Here, we highlight and summarize the latest developments in various ultrafast synthetic strategy with rapid energy input by heating shockwave and instant quenching for the synthesis of SACs, including Joule heating, microwave heating, solid-phase laser irradiation, flame-assisted method, arc-discharge method and so on, with special emphasis on how to achieve the uniform dispersion of single metal atoms at high metal loadings as well as the suitability for scalable production. Finally, we point out the advantages and disadvantages of the ultrafast heating strategies as well as the trends and challenges of future developments.

In the post-Moore era, as the energy consumption of micro-nano electronic devices rapidly increases, near-field radiative heat transfer (NFRHT) with super-Planckian phenomena has gradually shown great potential for applications in efficient and ultrafast thermal modulation and energy conversion. Recently, hyperbolic materials, an important class of anisotropic materials with hyperbolic isofrequency contours, have been intensively investigated. As an exotic optical platform, hyperbolic materials bring tremendous new opportunities for NFRHT from theoretical advances to experimental designs. To date, there have been considerable achievements in NFRHT for hyperbolic materials, which range from the establishment of different unprecedented heat transport phenomena to various potential applications. This review concisely introduces the basic physics of NFRHT for hyperbolic materials, lays out the theoretical methods to address NFRHT for hyperbolic materials, and highlights unique behaviors as realized in different hyperbolic materials and the resulting applications. Finally, key challenges and opportunities of the NFRHT for hyperbolic materials in terms of fundamental physics, experimental validations, and potential applications are outlined and discussed.

The growing demand for electronic devices, smart devices, and the Internet of Things constitutes the primary driving force for marching down the path of decreased critical dimension and increased circuit intricacy of integrated circuits. However, as sub-10 nm high-volume manufacturing is becoming the mainstream, there is greater awareness that defects introduced by original equipment manufacturer components impact yield and manufacturing costs. The identification, positioning, and classification of these defects, including random particles and systematic defects, are becoming more and more challenging at the 10 nm node and beyond. Very recently, the combination of conventional optical defect inspection with emerging techniques such as nanophotonics, optical vortices, computational imaging, quantitative phase imaging, and deep learning is giving the field a new possibility. Hence, it is extremely necessary to make a thorough review for disclosing new perspectives and exciting trends, on the foundation of former great reviews in the field of defect inspection methods. In this article, we give a comprehensive review of the emerging topics in the past decade with a focus on three specific areas: (a) the defect detectability evaluation, (b) the diverse optical inspection systems, and (c) the post-processing algorithms. We hope, this work can be of importance to both new entrants in the field and people who are seeking to use it in interdisciplinary work.

Developments in advanced manufacturing have promoted the miniaturization of semiconductor electronic devices to a near-atomic scale, which continuously follows the ‘top-down’ construction method. However, huge challenges have been encountered with the exponentially increased cost and inevitably prominent quantum effects. Molecular electronics is a highly interdisciplinary subject that studies the quantum behavior of electrons tunneling in molecules. It aims to assemble electronic devices in a ‘bottom-up’ manner on this scale through a single molecule, thereby shedding light on the future design of logic circuits with new operating principles. The core technologies in this field are based on the rapid development of precise fabrication at a molecular scale, regulation at a quantum scale, and related applications of the basic electronic component of the ‘electrode-molecule-electrode junction’. Therefore, the quantum charge transport properties of the molecule can be controlled to pave the way for the bottom-up construction of single-molecule devices. The review firstly focuses on the collection and classification of the construction methods for molecular junctions. Thereafter, various characterization and regulation methods for molecular junctions are discussed, followed by the properties based on tunneling theory at the quantum scale of the corresponding molecular electronic devices. Finally, a summary and perspective are given to discuss further challenges and opportunities for the future design of electronic devices.

Atomic and close-to-atomic scale manufacturing (ACSM) aims to provide techniques for manufacturing in various fields, such as circuit manufacturing, high energy physics equipment, and medical devices and materials. The realization of atomic scale material manipulation depending on the theoretical system of classical mechanics faces great challenges. Understanding and using intermolecular and surface forces are the basis for better designing of ACSM. Transformation of atoms based on scanning tunneling microscopy or atomic force microscopy (AFM) is an essential process to regulate intermolecular interactions. Self-assemble process is a thermodynamic process involving complex intermolecular forces. The competition of these interaction determines structure assembly and packing geometry. For typical nanomachining processes including AFM nanomachining and chemical mechanical polishing, the coupling of chemistry and stress (tribochemistry) assists in the removal of surface atoms. Furthermore, based on the principle of triboelectrochemistry, we expect a further reduction of the potential barrier, and a potential application in high-efficiency atoms removal and fabricating functional coating. Future fundamental research is proposed for achieving high-efficiency and high-accuracy manufacturing with the aiding of external field. This review highlights the significant contribution of intermolecular and surface forces to ACSM, and may accelerate its progress in the in-depth investigation of fundamentals.

Inspired by natural porous architectures, numerous attempts have been made to generate porous structures. Owing to the smooth surfaces, highly interconnected porous architectures, and mathematical controllable geometry features, triply periodic minimal surface (TPMS) is emerging as an outstanding solution to constructing porous structures in recent years. However, many advantages of TPMS are not fully utilized in current research. Critical problems of the process from design, manufacturing to applications need further systematic and integrated discussions. In this work, a comprehensive overview of TPMS porous structures is provided. In order to generate the digital models of TPMS, the geometry design algorithms and performance control strategies are introduced according to diverse requirements. Based on that, precise additive manufacturing methods are summarized for fabricating physical TPMS products. Furthermore, actual multidisciplinary applications are presented to clarify the advantages and further potential of TPMS porous structures. Eventually, the existing problems and further research outlooks are discussed.

Atomic and close-to-atomic scale manufacturing (ACSM) represents techniques for manufacturing high-end products in various fields, including future-generation computing, communication, energy, and medical devices and materials. In this paper, the theoretical boundary between ACSM and classical manufacturing is identified after a thorough discussion of quantum mechanics and their effects on manufacturing. The physical origins of atomic interactions and energy beams-matter interactions are revealed from the point view of quantum mechanics. The mechanisms that dominate several key ACSM processes are introduced, and a current numerical study on these processes is reviewed. A comparison of current ACSM processes is performed in terms of dominant interactions, representative processes, resolution and modelling methods. Future fundamental research is proposed for establishing new approaches for modelling ACSM, material selection or preparation and control of manufacturing tools and environments. This paper is by no means comprehensive but provides a starting point for further systematic investigation of ACSM fundamentals to support and accelerate its industrial scale implementation in the near future.

Micro/nanostructured components play an important role in micro-optics and optical engineering, tribology and surface engineering, and biological and biomedical engineering, among other fields. Precision glass molding technology is the most efficient method of manufacturing micro/nanostructured glass components, the premise of which is meld manufacturing with complementary micro/nanostructures. Numerous mold manufacturing methods have been developed to fabricate extremely small and high-quality micro/nanostructures to satisfy the demands of functional micro/nanostructured glass components for various applications. Moreover, the service performance of the mold should also be carefully considered. This paper reviews a variety of technologies for manufacturing micro/nanostructured molds. The authors begin with an introduction of the extreme requirements of mold materials. The following section provides a detailed survey of the existing micro/nanostructured mold manufacturing techniques and their corresponding mold materials, including nonmechanical and mechanical methods. This paper concludes with a detailed discussion of the authors recent research on nickel-phosphorus (Ni-P) mold manufacturing and its service performance.

Health monitoring of structures and people requires the integration of sensors and devices on various 3D curvilinear, hierarchically structured, and even dynamically changing surfaces. Therefore, it is highly desirable to explore conformal manufacturing techniques to fabricate and integrate soft deformable devices on complex 3D curvilinear surfaces. Although planar fabrication methods are not directly suitable to manufacture conformal devices on 3D curvilinear surfaces, they can be combined with stretchable structures and the use of transfer printing or assembly methods to enable the device integration on 3D surfaces. Combined with functional nanomaterials, various direct printing and writing methods have also been developed to fabricate conformal electronics on curved surfaces with intimate contact even over a large area. After a brief summary of the recent advancement of the recent conformal manufacturing techniques, we also discuss the challenges and potential opportunities for future development in this burgeoning field of conformal electronics on complex 3D surfaces.

Reliable fabrication of micro/nanostructures with sub-10 nm features is of great significance for advancing nanoscience and nanotechnology. While the capability of current complementary metal-oxide semiconductor (CMOS) chip manufacturing can produce structures on the sub-10 nm scale, many emerging applications, such as nano-optics, biosensing, and quantum devices, also require ultrasmall features down to single digital nanometers. In these emerging applications, CMOS-based manufacturing methods are currently not feasible or appropriate due to the considerations of usage cost, material compatibility, and exotic features. Therefore, several specific methods have been developed in the past decades for different applications. In this review, we attempt to give a systematic summary on sub-10 nm fabrication methods and their related applications. In the first and second parts, we give a brief introduction of the background of this research topic and explain why sub-10 nm fabrication is interesting from both scientific and technological perspectives. In the third part, we comprehensively summarize the fabrication methods and classify them into three main approaches, including lithographic, mechanics-enabled, and post-trimming processes. The fourth part discusses the applications of these processes in quantum devices, nano-optics, and high-performance sensing. Finally, a perspective is given to discuss the challenges and opportunities associated with this research topic.

Nuclear energy is a low-carbon, safe, efficient, and sustainable clean energy. The new generation of nuclear energy systems operate in harsher environments under higher working temperatures and irradiation doses, while traditional nuclear power materials cannot meet the requirements. The development of high-performance nuclear power materials is a key factor for promoting the development of nuclear energy. Oxide dispersion strengthened (ODS) steel contains a high number density of dispersed nano-oxides and defect sinks and exhibits excellent high temperature creep performance and irradiation swelling resistance. Therefore, ODS steel has been considered as one of the most promising candidate materials for fourth-generation nuclear fission reactor cladding tubes and nuclear fusion reactor blankets. The preparation process significantly influences microstructure of ODS steel. This paper reviews the development and perspective of several preparation processes of ODS steel, including the powder metallurgy process, improved powder metallurgy process, liquid metal forming process, hybrid process, and additive forging. This paper also summarizes and analyzes the relationship between microstructures and the preparation process. After comprehensive consideration, the powder metallurgy process is still the best preparation process for ODS steel. Combining the advantages and disadvantages of the above preparation processes, the trend applied additive forging for extreme manufacturing of large ODS steel components is discussed with the goal of providing a reference for the application and development of ODS steel in nuclear energy.

Diamond is a promising material for the modern industry. It is widely used in different applications, such as cutting tools, optical windows, heat dissipation, and semiconductors. However, these application areas require exceptionally flattened and polished diamond surfaces. Unfortunately, due to the extreme hardness and chemical inertness of diamond, the polishing of diamond is challenging. Since the 1920s, various conventional and modern mechanical, chemical, and thermal polishing techniques have been proposed and developed for finishing diamond surfaces. Therefore, to impart proper guidance on selecting a good polishing technique for production practice, this paper presents an in-depth and informative literature survey of the current research and engineering developments regarding diamond polishing. At first, a brief review of the general developments and basic material removal principles is discussed. This review concludes with a detailed analysis of each techniques’ polishing performance and critical challenges, and a discussion of the new insights and future applications of diamond polishing.

Additive manufacturing (AM) technology is considered one of the most promising manufacturing technologies in the aerospace and defense industries. However, AM components are known to have various internal defects, such as powder agglomeration, balling, porosity, internal cracks and thermal/internal stress, which can significantly affect the quality, mechanical properties and safety of final parts. Therefore, defect inspection methods are important for reducing manufactured defects and improving the surface quality and mechanical properties of AM components. This paper describes defect inspection technologies and their applications in AM processes. The architecture of defects in AM processes is reviewed. Traditional defect detection technology and the surface defect detection methods based on deep learning are summarized, and future aspects are suggested.

The brittle–ductile transition (BDT) widely exists in the manufacturing with extremely small deformation scale, thermally assisted machining, and high-speed machining. This paper reviews the BDT in extreme manufacturing. The factors affecting the BDT in extreme manufacturing are analyzed, including the deformation scale and deformation temperature induced brittle-to-ductile transition, and the reverse transition induced by grain size and strain rate. A discussion is arranged to explore the mechanisms of BDT and how to improve the machinability based on the BDT. It is proposed that the mutual transition between brittleness and ductility results from the competition between the occurrence of plastic deformation and the propagation of cracks. The brittleness or ductility of machined material should benefit a specific manufacturing process, which can be regulated by the deformation scale, deformation temperature and machining speed.

Additive manufacturing (AM) is an emerging customized three-dimensional (3D) functional product fabrication technology. It provides a higher degree of design freedom, reduces manufacturing steps, cost and production cycles. However, existing metallic component 3D printing techniques are mainly for the manufacture of single material components. With the increasing commercial applications of AM technologies, the need for 3D printing of more than one type of dissimilar materials in a single component increases. Therefore, investigations on multi-material AM (MMAM) emerge over the past decade. Lasers are currently widely used for the AM of metallic components where high temperatures are involved. Here we report the progress and trend in laser-based macro- and micro-scale AM of multiple metallic components. The methods covered in this paper include laser powder bed fusion, laser powder directed energy deposition, and laser-induced forward transfer for MMAM applications. The principles and process/material characteristics are described. Potential applications and challenges are discussed. Finally, future research directions and prospects are proposed.

Traditional electrode manufacturing for lithium-ion batteries is well established, reliable, and has already reached high processing speeds and improvements in production costs. For modern electric vehicles, however, the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing; and new production concepts are required for this purpose. During the last decade, laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances. Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines. This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art. Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements. The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale. However, promising developments in high-power, ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon. For demonstration in pilot lines adapted to future cell production, process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery. This review begins with an introduction of the three-dimensional battery and thick film concept, made possible by laser texturing. Laser processing of electrode components, namely current collectors, anodes, and cathodes will be presented. Different types of electrode architectures, such as holes, grids, and lines, were generated; their impact on battery performances are illustrated. The usage of high-energy materials, which are on the threshold of commercialization, is highlighted. Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes. This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.

Helium ion beam (HIB) technology plays an important role in the extreme fields of nanofabrication. This paper reviews the latest developments in HIB technology as well as its extreme processing capabilities and widespread applications in nanofabrication. HIB-based nanofabrication includes direct-write milling, ion beam- induced deposition, and direct-write lithography without resist assistance. HIB nanoscale applications have also been evaluated in the areas of integrated circuits, materials sciences, nano-optics, and biological sciences. This review covers four thematic applications of HIB: (1) helium ion microscopy imaging for biological samples and semiconductors; (2) HIB milling and swelling for 2D/3D nanopore fabrication; (3) HIB-induced deposition for nanopillars, nanowires, and 3D nanostructures; (4) additional HIB direct writing for resist, graphene, and plasmonic nanostructures. This paper concludes with a summary of potential future applications and areas of improvement for HIB extreme nanofabrication technology.

The rapid progress of micro/nanoelectronic systems and miniaturized portable devices has tremendously increased the urgent demands for miniaturized and integrated power supplies. Miniaturized energy storage devices (MESDs), with their excellent properties and additional intelligent functions, are considered to be the preferable energy supplies for uninterrupted powering of microsystems. In this review, we aim to provide a comprehensive overview of the background, fundamentals, device configurations, manufacturing processes, and typical applications of MESDs, including their recent advances. Particular attention is paid to advanced device configurations, such as two-dimensional (2D) stacked, 2D planar interdigital, 2D arbitrary-shaped, three-dimensional planar, and wire-shaped structures, and their corresponding manufacturing strategies, such as printing, scribing, and masking techniques. Additionally, recent developments in MESDs, including microbatteries and microsupercapacitors, as well as microhybrid metal ion capacitors, are systematically summarized. A series of on-chip microsystems, created by integrating functional MESDs, are also highlighted. Finally, the remaining challenges and future research scope on MESDs are discussed.

Directed self-assembly (DSA) emerges as one of the most promising new patterning techniques for single digit miniaturization and next generation lithography. DSA achieves high-resolution patterning by molecular assembly that circumvents the diffraction limit of conventional photolithography. Recently, the International Roadmap for Devices and Systems listed DSA as one of the advanced lithography techniques for the fabrication of 3–5 nm technology node devices. DSA can be combined with other lithography techniques, such as extreme ultra violet (EUV) and 193 nm immersion (193i), to further enhance the patterning resolution and the device density. So far, DSA has demonstrated its superior ability for the fabrication of nanoscale devices, such as fin field effect transistor and bit pattern media, offering a variety of configurations for high-density integration and low-cost manufacturing. Over 1 T in?2 device density can be achieved either by direct templating or coupled with nanoimprinting to improve the throughput. The development of high χ block copolymer further enhances the patterning resolution of DSA. In addition to its superiority in high-resolution patterning, the implementation of DSA on a 300 mm pivot line fully demonstrates its potential for large-scale, high-throughput, and cost-effective manufacturing in industrial environment.

Laser-assisted manufacturing (LAM) is a technique that performs machining of materials using a laser heating process. During the process, temperatures can rise above over 2000 ?C. As a result, it is crucial to explore the thermal behavior of materials under such high temperatures to understand the physics behind LAM and provide feedback for manufacturing optimization. Raman spectroscopy, which is widely used for structure characterization, can provide a novel way to measure temperature during LAM. In this review, we discuss the mechanism of Raman-based temperature probing, its calibration, and sources of uncertainty/error, and how to control them. We critically review the Raman-based temperature measurement considering the spatial resolution under near-field optical heating and surface structure-induced asymmetries. As another critical aspect of Raman-based temperature measurement, temporal resolution is also reviewed to cover various ways of realizing ultrafast thermal probing. We conclude with a detailed outlook on Raman-based temperature probing in LAM and issues that need special attention.

High entropy alloys (HEAs) with multi-component solid solution microstructures have the potential for large-scale industrial applications due to their excellent mechanical and functional properties. However, the mechanical properties of HEAs limit the selection of processing technologies. Additive manufacturing technology possesses strong processing adaptability, making itthe best candidate method to overcome this issue. This comprehensive review examines the current state of selective laser melting (SLM) of HEAs. Introducing SLM to HEAs processing is motivated by its high quality for dimensional accuracy, geometric complexity, surface roughness, and microstructure. This review focuses on analyzing the current developments and challenges in SLM of HEAs, including defects, microstructures, and properties, as well as strengthing prediction models of fabricated HEAs. This review also offers directions for future studies to address existing challenges and promote technological advancement.

Femtosecond laser direct writing (FLDW) has been widely employed in controllable manufacturing of biomimetic micro/nanostructures due to its specific advantages including high precision, simplicity, and compatibility for diverse materials in comparison with other methods (e.g. ion etching, sol-gel process, chemical vapor deposition, template method, and self-assembly). These biomimetic micro/nanostructured surfaces are of significant interest for academic and industrial research due to their wide range of potential applications, including self-cleaning surfaces, oil-water separation, and fog collection. This review presents the inherent relationship between natural organisms, fabrication methods, micro/nanostructures and their potential applications. Thereafter, we throw a list of current fabrication strategies so as to highlight the advantages of FLDW in manufacturing bioinspired microstructured surfaces. Subsequently, we summarize a variety of typical bioinspired designs (e.g. lotus leaf, pitcher plant, rice leaf, butterfly wings, etc) for diverse multifunctional micro/nanostructures through extreme femtosecond laser processing technology. Based on the principle of interfacial chemistry and geometrical optics, we discuss the potential applications of these functional micro/nanostructures and assess the underlying challenges and opportunities in the extreme fabrication of bioinspired micro/nanostructures by FLDW. This review concludes with a follow up and an outlook of femtosecond laser processing in biomimetic domains.

Complex thin-walled titanium alloy components play a key role in the aircraft, aerospace and marine industries, offering the advantages of reduced weight and increased thermal resistance. The geometrical complexity, dimensional accuracy and in-service properties are essential to fulfill the high-performance standards required in new transportation systems, which brings new challenges to titanium alloy forming technologies. Traditional forming processes, such as superplastic forming or hot pressing, cannot meet all demands of modern applications due to their limited properties, low productivity and high cost. This has encouraged industry and research groups to develop novel high-efficiency forming processes. Hot gas pressure forming and hot stamping-quenching technologies have been developed for the manufacture of tubular and panel components, and are believed to be the cut-edge processes guaranteeing dimensional accuracy, microstructure and mechanical properties. This article intends to provide a critical review of high-efficiency titanium alloy forming processes, concentrating on latest investigations of controlling dimensional accuracy, microstructure and properties. The advantages and limitations of individual forming process are comprehensively analyzed, through which, future research trends of high-efficiency forming are identified including trends in process integration, processing window design, full cycle and multi-objective optimization. This review aims to provide a guide for researchers and process designers on the manufacture of thin-walled titanium alloy components whilst achieving high dimensional accuracy and satisfying performance properties with high efficiency and low cost.

Three types of scanning strategies, including the chessboard scanning strategy, the zigzag scanning strategy and the remelting scanning strategy, were conducted to study the effects of scanning strategies on surface morphology, microstructure, mechanical properties and the grain orientation of selective laser melted pure tungsten. The results showed that the pores and cracks were main defects in SLM-processed tungsten parts. The pores could be eliminated using the remelting scanning strategy. However, the cracks seemed to be inevitable regardless of the applied scanning strategies. The microstructures of SLM-processed tungsten were columnar grains and showed strong epitaxial growth along the building direction. A compressive strength of 923 MPa with an elongation of 7.7% was obtained when the zigzag scanning strategy was applied, which was the highest among the three scanning strategies. By changing the scanning strategies, the texture of SLM-processed tungsten in the direction of processing could be changed.

Projection micro stereolithography (PμSL) is a high-resolution (up to 0.6 μm) 3D printing technology based on area projection triggered photopolymerization, and capable of fabricating complex 3D architectures covering multiple scales and with multiple materials. This paper reviews the recent development of the PμSL based 3D printing technologies, together with the related applications. It introduces the working principle, the commercialized products, and the recent multiscale, multimaterial printing capability of PμSL as well as some functional photopolymers that are suitable to PμSL. This review paper also summarizes a few typical applications of PμSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.

Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing. The laser interferometer is one of the most important measurement tools invented in the 20th century. Today, it is commonly used in ultraprecision machining and manufacturing, ultraprecision positioning control, and many noncontact optical sensing technologies. So far, the state-of-the-art laser interferometers are the ground-based gravitational-wave detectors, e.g. the Laser Interferometer Gravitational-wave Observatory (LIGO). The LIGO has reached the measurement quantum limit, and some quantum technologies with squeezed light are currently being tested in order to further decompress the noise level. In this paper, we focus on the laser interferometry developed for space-based gravitational-wave detection. The basic working principle and the current status of the key technologies of intersatellite laser interferometry are introduced and discussed in detail. The launch and operation of these large-scale, gravitational-wave detectors based on space-based laser interferometry is proposed for the 2030s.

In the past decades, Moore’s law drives the semiconductor industry to continuously shrink the critical size of transistors down to 7 nm. As transistors further downscaling to smaller sizes, the law reaches its limitation, and the increase of transistors density on the chip decelerates. Up to now, extreme ultraviolet lithography has been used in some key steps, and it is facing alignment precision and high costs for high-volume manufacturing. Meanwhile, the introduction of new materials and 3D complex structures brings serious challenges for top-down methods. Thus, bottom-up schemes are believed to be necessary methods combined with the top-down processes. In this article, atomic level deposition methods are reviewed and categorized to extend Moore’s law and beyond. Firstly, the deposition brings lateral angstrom resolution to the vertical direction as well as top-down etching, such as double patterning, transfer of nanowires, deposition of nanotubes, and so on. Secondly, various template-assisted selective deposition methods including dielectric templates, inhibitors and correction steps have been utilized for the alignment of 3D complex structures. Higher resolution can be achieved by inherently selective deposition, and the underlying selective mechanism is discussed. Finally, the requirements for higher precision and efficiency manufacturing are also discussed, including the equipment, integration processes, scale-up issues, etc. The article reviews low dimensional manufacturing and integration of 3D complex structures for the extension of Moore’s law in semiconductor fields, and emerging fields including but not limited to energy, catalysis, sensor and biomedicals.

Due to the rapid development of precision manufacturing technology, much research has been conducted in the field of multisensor measurement and data fusion technology with a goal of enhancing monitoring capabilities in terms of measurement accuracy and information richness, thereby improving the efficiency and precision of manufacturing. In a multisensor system, each sensor independently measures certain parameters. Then, the system uses a relevant signalprocessing algorithm to combine all of the independent measurements into a comprehensive set of measurement results. The purpose of this paper is to describe multisensor measurement and data fusion technology and its applications in precision monitoring systems. The architecture of multisensor measurement systems is reviewed, and some implementations in manufacturing systems are presented. In addition to the multisensor measurement system, related data fusion methods and algorithms are summarized. Further perspectives on multisensor monitoring and data fusion technology are included at the end of this paper.

This paper introduces the recent progress in methodologies and their related applications based on the soft x-ray interference lithography beamline in the Shanghai synchrotron radiation facility. Dual-beam, multibeam interference lithography and Talbot lithography have been adopted as basic methods in the beamline. To improve the experimental performance, a precise real-time vibration evaluation system has been established; and the lithography stability has been greatly improved. In order to meet the demands for higher resolution and practical application, novel experimental methods have been developed, such as high-order diffraction interference exposure, high-aspect-ratio and large-area stitching exposure, and parallel direct writing achromatic Talbot lithography. As of now, a 25 nm half-pitch pattern has been obtained; and a cm2 exposure area has been achieved in practical samples. The above methods have been applied to extreme ultraviolet photoresist evaluation, photonic crystal and surface plasmonic effect research, and so on.

The additive manufacturing (AM) process plays an important role in enabling cross-disciplinary research in engineering and personalised medicine. Commercially available clinical tools currently utilised in radiotherapy are typically based on traditional manufacturing processes, often leading to non-conformal geometries, time-consuming manufacturing process and high costs. An emerging application explores the design and development of patient-specific clinical tools using AM to optimise treatment outcomes among cancer patients receiving radiation therapy. In this review, we: 1)? highlight the key advantages of AM in radiotherapy where rapid prototyping allows for patient-specific manufacture 2) explore common clinical workflows involving radiotherapy tools such as bolus, compensators, anthropomorphic phantoms, immobilisers, and brachytherapy moulds; 3) investigate how current AM processes are exploited by researchers to achieve patient tissuelike imaging and dose attenuations. Finally, significant AM research opportunities in this space are highlighted for their future advancements in radiotherapy for diagnostic and clinical research applications.

The increase in both power and packing densities in power electronic devices has led to an increase in the market demand for effective heat-dissipating materials with a high thermal conductivity and thermal expansion coefficient compatible with chip materials while still ensuring the reliability of the power modules. Metal matrix composites, especially copper matrix composites, containing carbon fibers, carbon nanofibers, or diamond are considered very promising as the next generation of thermalmanagement materials in power electronic packages. These composites exhibit enhanced thermal properties, as compared to pure copper, combined with lower density. This paper presents powder metallurgy and hot uniaxial pressing fabrication techniques for copper/carbon composite materials which promise to be efficient heat-dissipation materials for power electronic modules. Thermal analyses clearly indicate that interfacial treatments are required in these composites to achieve high thermal and thermomechanical properties. Control of interfaces (through a novel reinforcement surface treatment, the addition of a carbide-forming element inside the copper powders, and processing methods), when selected carefully and processed properly, will form the right chemical/ mechanical bonding between copper and carbon, enhancing all of the desired thermal and thermomechanical properties while minimizing the deleterious effects. This paper outlines a variety of methods and interfacial materials that achieve these goals.

Diamond tools play a critical role in ultra-precision machining due to their excellent physical and mechanical material properties, such as that cutting edge can be sharpened to nanoscale accuracy. However, abrasive chemical reactions between diamond and non-diamond-machinable metal elements, including Fe, Cr, Ti, Ni, etc, can cause excessive tool wear in diamond cutting of such metals and most of their alloys. This paper reviews the latest achievements in the chemical wear and wear suppression methods for diamond tools in cutting of ferrous metals. The focus will be on the wear mechanism of diamond tools, and the typical wear reduction methods for diamond cutting of ferrous metals, including ultrasonic vibration cutting, cryogenic cutting, surface nitridation and plasma assisted cutting, etc. Relevant commercially available devices are introduced as well. Furthermore, future research trends in diamond tool wear suppression are discussed and examined.

Hard coatings are extensively required in industry for protecting mechanical/structural parts that withstand extremely high temperature, stress, chemical corrosion, and other hostile environments. Electrical discharge coating (EDC) is an emerging surface modification technology to produce such hard coatings by using electrical discharges to coat a layer of material on workpiece surface to modify and enhance the surface characteristics or create new surface functions. This paper presents a comprehensive overview of EDC technologies for various materials, and summarises the types and key parameters of EDC processes as well as the characteristics of resulting coatings. It provides a systematic summary of the fundamentals and key features of the EDC processes, as well as its applications and future trends.

Semiconductor and laser single crystals are usually brittle and hard, which need to be ground to have satisfactory surface integrity and dimensional precision prior to their applications. Improvement of the surface integrity of a ground crystal can shorten the time of a subsequent polishing process, thus reducing the manufacturing cost. The development of cost-effective grinding technologies for those crystals requires an in-depth understanding of their deformation and removal mechanisms. As a result, a great deal of research efforts were directed towards studying this topic in the past two or three decades. In this review, we aimed to summarize the deformation and removal characteristics of representative semiconductor and laser single crystals in accordance with the scale of mechanical loading, especially at extremely small scales. Their removal mechanisms were critically examined based on the evidence obtained from highresolution TEM analyses. The relationships between machining conditions and removal behaviors were discussed to provide a guidance for further advancing of the grinding technologies for those crystals.

Glass welding by ultra-short pulsed (USP) lasers is a piece of technology that offers high strength joints with hermetic sealing. The joints are typically formed in glass that is transparent to the laser by exploiting nonlinear absorption effects that occur under extreme conditions. Though the temperature reached during the process is on the order of a few 1000 °C, the heat affected zone (HAZ) is confined to only tens of micrometers. It is this controlled confinement of the HAZ during the joining process that makes this technology so appealing to a multitude of applications because it allows the foregoing of a subsequent tempering step that is typically essential in other glass joining techniques, thus making it possible to effectively join highly heat sensitive components. In this work, we give an overview on the process, development and applications of glass welding by USP lasers.

The importance to industry of non-contact bearings is growing rapidly as the demand for highspeed and high-precision manufacturing equipment increases. As a recently developed non-contact technology, near-field acoustic levitation (NFAL) has drawn much attention for the advantages it offers, including no requirement for an external pressurized air supply, its compact structure, and its ability to adapt to its environment. In this paper, the working mechanism of NFAL is introduced in detail and compared to all existing non-contact technologies to demonstrate its versatility and potential for practical applications in industry. The fundamental theory of NFAL, including gas film lubrication theory and acoustic radiation pressure theory is presented. Then, the current stateof- the-art of the design and development of squeeze film air bearings based on NFAL is reviewed. Finally, future trends and obstacles to more widespread use are discussed.

In this review, we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet (EUV) lithography. EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors. Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips. Fabrication and inspection of defect-free masks, however, still remain critical issues in EUV technology. Thus, in our pursuit for a resolution, we have developed the coherent EUV scatterometry microscope (CSM) system with a synchrotron radiation (SR) source to establish the actinic metrology, along with inspection algorithms. The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms. To expedite the practical application of the CSM, we have also developed a standalone CSM, based on high-order harmonic generation, as an alternative to the SR-CSM. Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern, diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed. Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure, an aperiodic angle edge structure, as well as a cross pattern in an EUV mask.

Femtosecond laser technology has attracted significant attention from the viewpoints of fundamental and application; especially femtosecond laser processing materials present the unique mechanism of laser-material interaction. Under the extreme nonequilibrium conditions imposed by femtosecond laser irradiation, many fundamental questions concerning the physical origin of the material removal process remain unanswered. In this review, cutting-edge ultrafast dynamic observation techniques for investigating the fundamental questions, including timeresolved pump-probe shadowgraphy, ultrafast continuous optical imaging, and four-dimensional ultrafast scanning electron microscopy, are comprehensively surveyed. Each technique is described in depth, beginning with its basic principle, followed by a description of its representative applications in laser-material interaction and its strengths and limitations. The consideration of temporal and spatial resolutions and panoramic measurement at different scales are two major challenges. Hence, the prospects for technical advancement in this field are discussed finally.

Microcutting is a precision technology that offers flexible fabrication of microfeatures or complex three-dimensional components with high machining accuracy and superior surface quality. This technology may offer great potential as well as advantageous process capabilities for the machining of hard-to-cut materials, such as tungsten carbide. The geometrical design and dimension of the tool cutting edge is a key factor that determines the size and form accuracy possible in the machined workpiece. Currently, the majority of commercial microtools are scaled-down versions of conventional macrotool designs. This approach does not impart optimal performance due to size effects and associated phenomena. Consequently, in-depth analysis and implementation of microcutting mechanics and fundamentals are required to enable successful industrial adaptation in microtool design and fabrication methods. This paper serves as a review of recent microtool designs, materials, and fabrication methods. Analysis of tool performance is discussed, and new approaches and techniques are examined. Of particular focus is tool wear suppression in the machining of hard materials and associated process parameters, including internal cooling and surface patterning techniques. The review concludes with suggestions for an integrated design and fabrication process chain which can aid industrial microtool manufacture.

Halide perovskites have rapidly attracted considerable attention due to unprecedented properties not seen in traditional semiconductors. In addition to their optoelectronic merits, one advantage of perovskite materials is their solution processability, which opens the door to low-cost and high throughput solution coating strategies for the commercialization of perovskite solar cells (PSCs). Here we review perovskite film fabrication by meniscus coating—a simple and readily scalable manufacturing technique, including blade coating and slot-die coating.We outline the fundamental fluid mechanisms of meniscus coating, discuss drying and crystallization of perovskite in the coating process, and provide an overview of recent progress in meniscus-coated PSCs.

Material embrittlement is often encountered in machining, heat treatment, hydrogen and lowtemperature conditions among which machining is strain-rate related. More strain-rate evoked embrittlement is expected in material loading processes, such as in high-speed machining and projectile penetration. In order to understand the fundamental mechanisms of the strain-rate evoked material embrittlement, this study is concerned with the material responses to loading at high strain-rates. It then explores the strain-rate evoked material embrittlement and fragmentation during high strain-rate loading processes and evaluates various empirical and physical models from different researchers for the assessment of the material embrittlement. The study proposes strain-rate sensitivity for the characterization of material embrittlement and the concept of the pseudo embrittlement for material responses to very high strain-rates. A discussion section is arranged to explore the underlying mechanisms of the strain-rate evoked material embrittlement and fragmentation based on dislocation kinetics.

In order to meet the requirements of high reliability, long-lifetime and lightweight in a new generation of aerospace, aviation, high-speed train, and energy power equipment, integrated components are urgently needed to replace traditional multi-piece, welded components. The applications of integrated components involve in a series of large-size, complex-shaped, highperformance components made of difficult-to-deform materials, which present a huge challenge for forming ultra-large size integrated components. In this paper, the developments and perspectives of several extreme forming technologies are reviewed, including the sheet hydroforming of ultra-large curved components, dieless hydroforming of ellipsoidal shells, radial-axial ring rolling of rings, in situ manufacturing process of flanges, and local isothermal forging of titanium alloy components. The principle and processes for controlling deformation are briefly illustrated. The forming of typical ultra-large size integrated components and industrial applications are introduced, such as the high strength aluminum alloy, 3m in diameter, integrated tank dome first formed by using a sheet blank with a thickness the same as the final component, and a 16m diameter, integrated steel ring rolled by using a single billet. The trends for extreme forming of ultra-large size integrated components are discussed with a goal of providing ideas and fundamental guidance for the further development of new forming processes for extreme-size integrated components in the future.

Precision is one of the most important aspects of manufacturing. High precision creates high quality, high performance, exchangeability, reliability, and added value for industrial products. Over the past decades, remarkable advances have been achieved in the area of high-precision manufacturing technologies, where the form accuracy approaches the nanometer level and surface roughness the atomic level. These extremely high precision manufacturing technologies enable the development of high-performance optical elements, semiconductor substrates, biomedical parts, and so on, thereby enhancing the ability of human beings to explore the macroand microscopic mysteries and potentialities of the natural world. In this paper, state-of-the-art high-precision material removal manufacturing technologies, especially ultraprecision cutting, grinding, deterministic form correction polishing, and supersmooth polishing, are reviewed and compared with insights into their principles, methodologies, and applications. The key issues in extreme precision manufacturing that should be considered for future R&D are discussed.

This paper proposes the ‘skin effect’ of the machining-induced damage at high strain rates. The paper first reviews the published research work on machining-induced damage and then identifies the governing factors that dominate damage formation mechanisms. Among many influential factors, such as stress–strain field, temperature field, material responses to loading and loading rate, and crack initiation and propagation, strain rate is recognized as a dominant factor that can directly lead to the ‘skin effect’ of material damage in a loading process. The paper elucidates that material deformation at high strain rates (>103 s-1) leads to the embrittlement, which in turn contributes to the ‘skin effect’ of subsurface damage. The paper discusses the ‘skin effect’ based on the principles of dislocation kinetics and crack initiation and propagation. It provides guidance to predicting the material deformation and damage at a high strain-rate for applications ranging from the armor protection, quarrying, petroleum drilling, and high-speed machining of engineering materials (e.g. ceramics and SiC reinforced aluminum alloys).

The fabrication of miniature structures on components with high-integrity surface quality represents one of the cutting edge technologies in the 21st century. The materials used to construct such small structures are often difficult-to-machine. Many other readily available technologies either cannot realise necessary precision or are costly. Abrasive waterjet (AWJ) is a favourable technology for the machining of difficult-to-machine materials. However, this technology is generally aimed at large stock removal. A reduction in the scale of this technology is an attractive avenue for meeting the pressing need of industry in the production of damage-free micro features. This paper reviews some of the work that has been undertaken at UNSW Sydney about the development of such an AWJ technology, focusing on the system design currently employed to generate a micro abrasive jet, the erosion mechanisms associated with processing some typical brittle materials of both single- and two-phased. Processing models based on the findings are also presented. The review concludes on the viability of the technology and the prevailing trend in its development.

This review focuses on recent developments in additive manufacturing (AM) of precision optical devices, particularly devices consisting of components with critical features at the micro- and nanoscale. These include, but are not limited to, microlenses, diffractive optical elements, and photonic devices. However, optical devices with large-size lenses and mirrors are not specifically included as this technology has not demonstrated feasibilities in that category. The review is roughly divided into two slightly separated topics, the first on meso- and microoptics and the second on optics with nanoscale features. Although AM of precision optics is still in its infancy with many unanswered questions, the references cited on this exciting topic demonstrate an enabling technology with almost unlimited possibilities. There are many high quality reviews of AM processes of non-optical components, hence they are not the focus of this review. The main purpose of this review is to start a conversion on optical fabrication based on information about 3D AM methods that has been made available to date, with an ultimate long-term goal of establishing new optical manufacturing methods that are low cost and highly precise with extreme flexibility.

Composite materials exhibit advantages from the combination of multiple properties, which cannot be achieved by a monolithic material. At present, the use of composite materials in miniaturized scale is receiving much attention in the fields of medicine, electronics, aerospace, and microtooling. A common method for producing miniaturized composite parts is micromanufacturing. There has been, however, no comprehensive literature published that reviews, compares, and discusses the ongoing micromanufacturing methods for producing miniaturized composite components. This study identifies the major micromanufacturing methods used with composite materials, categorizes their subclasses, and highlights the latest developments, new trends, and effects of key factors on the productivity, quality, and cost of manufacturing composite materials. A comparative study is presented that shows the potential and versatility associated with producing composite materials along with possible future applications. This review will be helpful in promoting micromanufacturing technology for fabricating miniaturized products made of composite materials to meet the growing industrial demand.

The extremely high peak intensity associated with ultrashort pulse width of femtosecond (fs) lasers enabled inducing nonlinear multiphoton absorption in materials that are transparent to the laser wavelength. More importantly, focusing the fs laser beam inside the transparent materials confined the nonlinear interaction to within the focal volume only, realizing three-dimensional (3D) micro/nanofabrication. This 3D capability offers three different processing schemes for use in fabrication: undeformative, subtractive, and additive. Furthermore, a hybrid approach of different schemes can create much more complex 3D structures and thereby promises to enhance the functionality of the structures created. Thus, hybrid fs laser 3D microprocessing opens a new door for material processing. This paper comprehensively reviews different types of hybrid fs laser 3D micro/nanoprocessing for diverse applications including fabrication of functional micro/nanodevices.

This article summarizes work at the Laser Thermal Laboratory and discusses related studies on the laser synthesis and functionalization of semiconductor nanostructures and two-dimensional (2D) semiconductor materials. Research has been carried out on the laser-induced crystallization of thin films and nanostructures. The in situ transmission electron microscopy (TEM) monitoring of the crystallization of amorphous precursors in nanodomains is discussed herein. The directed assembly of silicon nanoparticles and the modulation of their optical properties by phase switching is presented. The vapor–liquid–solid mechanism has been adopted as a bottom-up approach in the synthesis of semiconducting nanowires (NWs). In contrast to furnace heating methods, laser irradiation offers high spatial selectivity and precise control of the heating mechanism in the time domain. These attributes enabled the investigation of NW nucleation and the early stage of nanostructure growth. Site- and shape-selective, on-demand direct integration of oriented NWs was accomplished. Growth of discrete silicon NWs with nanoscale location selectivity by employing near-field laser illumination is also reported herein. Tuning the properties of 2D transition metal dichalcogenides (TMDCs) by modulating the free carrier type, density, and composition can offer an exciting new pathway to various practical nanoscale electronics. In situ Raman probing of laser-induced processing of TMDC flakes was conducted in a TEM instrument.

Human beings have witnessed unprecedented developments since the 1760s using precision tools and manufacturing methods that have led to ever-increasing precision, from millimeter to micrometer, to single nanometer, and to atomic levels. The modes of manufacturing have also advanced from craft-based manufacturing in the Stone, Bronze, and Iron Ages to precisioncontrollable manufacturing using automatic machinery. In the past 30 years, since the invention of the scanning tunneling microscope, humans have become capable of manipulating single atoms, laying the groundwork for the coming era of atomic and close-to-atomic scale manufacturing (ACSM). Close-to-atomic scale manufacturing includes all necessary steps to convert raw materials, components, or parts into products designed to meet the user’s specifications. The processes involved in ACSM are not only atomically precise but also remove, add, or transform work material at the atomic and close-to-atomic scales. This review discusses the history of the development of ACSM and the current state-of-the-art processes to achieve atomically precise and/or atomic-scale manufacturing. Existing and future applications of ACSM in quantum computing, molecular circuitry, and the life and material sciences are also described. To further develop ACSM, it is critical to understand the underlying mechanisms of atomic-scale and atomically precise manufacturing; develop functional devices, materials, and processes for ACSM; and promote high throughput manufacturing.