Significance Continuous miniaturization of traditional silicon electronic devices and photoelectric components increases the integration and performance of devices and introduces some undesirable problems caused by the size and quantum effects, and increased power consumption. Thus, the development of multifunctional next-generation nano-devices with more excellent performance than traditional devices is inevitable and significant in the post-Moore era. Owing to the excellent mechanical, thermal, electrical, and optical properties of nanomaterials, such as nanoparticles, quantum dots, nanowires, nanotubes, and two-dimensional (2D) materials, many studies have suggested that these materials are suitable for channel or electrode of multifunctional and high-performance nano-devices. Thus, the study and development of nano-devices based on nanomaterials are crucial for solving the bottleneck problems of electronics in the future.

Recently, abundant theoretical and experimental results have demonstrated that bending, folding, twisting a single nanomaterial, and arranging, assembling, connecting several nanomaterials can improve properties further or bring extraordinary characteristics of nano-devices. For instance, compared with chemical doping and contact engineering, deformation of 2D materials can solve the Fermi-level pinning and carrier concentration decreasing in nano-devices and may introduce new phenomena, such as piezotronics and piezo-phototronics. Thus, methods and accompanying systems for moving, arranging, deforming nanomaterials, and fabricating nano-structures and nano-devices will be crucial and indispensable in the electronics field in the future. The most “top-down” approaches for fabricating electronic and optoelectronic devices, such as ultraviolet lithography, electron beam lithography, and laser writing, are unfit for the mentioned purpose. Instead, nano-manipulation technology, as a “bottom-up” method, is proposed to move or spin atoms, nanomaterials, and cells in the nanoscale resolution. Based on this, it is promising in moving, deforming, and assembling nanomaterials in high-precision than other methods. For example, some indirect methods for bending 2D materials (e.g., thermal expansion mismatch, deformation of flexible substrates, and substrate surface topography modification) exist some problems, such as slipping of materials, small deformation, and uncontrollability. Nano-manipulation can use probes to push or fold materials in nano-/micro-scale directly and achieve large, complex, and controllable deformation. With electron beam-induced deposition, laser processing, and nano-welding, this technology can also develop nano-structures with excellent properties, weld a single material onto an electrode to fabricate devices, and test properties of a single material and device. Thus, it provides a new idea for the development of new-generation nano-devices with excellent performance.

Among many nano-manipulation techniques, methods and systems based on the microscopes with nano-level imaging accuracy, e.g., scanning probe microscope (SPM) and electron microscope (EM), are widely used. With the microscope monitor, the system controls the motion module to move the probes, tweezers and other manipulation tools in high-precision, and then moves, picks up, and bends nanoparticles (NPs), nanowires (NWs), and 2D materials. Besides, optical tweezers, magnetic tweezers, and acoustic tweezers can apply force to materials and trap or move these further by controlling the optical, magnetic, and sound fields. To develop nano-devices, manipulation methods based on SPM, EM, and optical tweezers are promising and anticipated. Thus, it is necessary and significant to introduce and summarize the recent studies in these nano-manipulation methods and understand their application in nano-devices.

Progress This study introduces the recent research in nano-manipulation based on scanning probe microscope(SPM), electron microscope(EM), and optical tweezers. For SPM manipulation, the principles and typical process demonstrate the capacity for accurately moving particles of tens to a few nanometers in diameter and weakness in real-time imaging, efficient and complex manipulation. For real-time imaging during manipulation, representative improvements include strategy optimization and development of parallel imaging/manipulation system (Fig. 2). The strategy optimization can also improve the success rate and efficiency, like sequential parallel pushing and virtual nano-hand strategies. To achieve three-dimensional (3D) and complex manipulation, researchers proposed new approaches to pile up nanoparticles and nanowires using a special substrate or two probes. With the development of strategies and systems, SPM manipulation applications were proposed in the field of nano-devices, such as testing mechanical and electronic properties, building plasma nano-structures, and fabricating electrodes of nano-devise. To achieve real-time imaging, Fukuda' group concentrated on EM manipulation. They invented nanorobotic manipulators inside the scanning electron microscope (SEM) and used it to stretch nanotubes, cut cells, and test mechanical properties (Fig. 5). EM manipulation is more suitable than SPM manipulation for complicated works due to real-time imaging and flexible manipulators. Complex manipulators also cause noise and drift in EM imaging. Sun' group invented various manipulators for compatibility with EM. Another major drawback of EM manipulation is the lack of depth information, which is critical to judge the contact between probes and materials. Thus, touchdown sensor, piezo fine positioner, laser displacement sensor, and other improvements are used to acquire precise 3D information. EM manipulation is wildly used in bending and twisting materials, nano-welding, fabricating transistors because of its flexibility. Optical tweezers are used in trapping nanoparticles and nanowires. Especially, near-field optical tweezers can trap particles up to several nanometers in diameter. To achieve a successful and superior manipulation, researchers concentrated on the enhancement of the optical field. Besides, fiber probes were suggested for trapping then moving nanomaterials. These researches showed optical tweezers are potential for manipulating smaller objectives to develop nano-devices.

Conclusions and Prospects SPM manipulation, EM manipulation, and optical tweezers have their advantages, limitations, and applications (Table 1). These provide new ideas and technical means for moving and assembling nanomaterials and manufacturing nano-structures and nano-devices. However, these methods and systems also face technical and scientific challenges. Thus, the development of integrated manipulation methods and systems will facilitate the applications in the field of nanoscience and electronics.