The evolution of information technology has propelled the advancement of sensors into a new era, referred to as Sensors 4.0^[1]. This era is characterized by the integration of key technological developments, including the internet of things (IoT), Industry 4.0, big data, artificial intelligence (AI), robotics, and digital health. These innovations necessitate that sensors become increasingly interconnected and intelligent. The concept of "everything is connected" demands that sensors undertake a broader and more complex range of tasks, a challenge that conventional, bulky devices are ill-equipped to address. In addition to pursuing improvements in sensitivity and bandwidth, as seen in the "more Moore" approach—focused on extracting the last few nanometers from process nodes—the paradigm of "more than and beyond Moore" presents new opportunities in the Sensors 4.0 era.

A key breakthrough in this context is the development of devices with flexibility, which introduces a new mechanical dimension to the conventional sensor form factor. This innovation lays the foundation for next-generation distributed sensory applications that are deformable, miniaturized, and lightweight. Furthermore, recent advancements in multimodal, biomimetic, AI-enhanced, and all-in-one sensing materials and devices are pushing the boundaries of smart electronics. These developments aim to achieve minimal power consumption while enhancing overall functionality. Consequently, flexibility and intelligence have emerged as two critical features driving the development of novel and compelling electronic sensory applications in Sensors 4.0, thus lead to the organization of our Special Issue at the very beginning of 2025 that collects critical research progress and strategical reviews across multidisciplinary subjects of flexible and smart electronics. Specifically, this Special Issue features six research articles and ten review articles contributed by leading experts in the field, categorized into three themes: 1) Sensory applications for light, gas, and temperature measurement, focusing on the fabrication and design of flexible platforms; 2) neuromorphic electronic devices that integrate sensing, memory, and computation to develop next-generation parallel and low-power sensory systems; 3) integrated and multimodal sensory systems for IoT applications in areas such as biology and healthcare.

The Special Issue opens with an overview by Hu et al. on the recent advancements in flexible perovskite photodetectors, addressing the critical issue of stability and highlighting the strategies developed for enhancing the performance of photoactive materials and device structures^[2]. Yang et al. then explore weak-light detection utilizing flexible perovskite devices, discussing the current technological landscape, associated challenges, and future prospects^[3]. Liang et al. provide a comprehensive review of design strategies for flexible sensors, particularly in the context of infrared sensing. Their discussion encompasses fundamental principles, material selection, fabrication techniques, and the architectural and functional integration required for applications in wearable optoelectronics and advanced image sensing^[4]. Liao et al. focus on elemental tellurium as a material of interest for IoT sensory applications, examining its critical roles in photodetectors, gas sensors, and energy harvesting devices^[5]. Li et al. investigate five significant groups of 2D materials and their corresponding sensory applications, emphasizing their potential for recognizing and converting human body and environmental signals^[6]. Yang et al. review recent advancements in implantable temperature sensors, concentrating on material selection and mechanisms, with a particular emphasis on biological applications^[7]. Finally, Thakur et al. present a straightforward ink writing method for fabricating nickel oxide-based thin films aimed at room temperature gas detection^[8].

We extend our heartfelt gratitude to all the authors for their invaluable contributions to this dynamic field of applied research. We also appreciate the experts who generously volunteered their time and expertise during the peer review process. Last but not least, we are particularly thankful to the Journal of Semiconductors Editorial Office for their dedicated efforts in bringing this special section to fruition.

This Special Issue compiles significant and thought-provoking research advancements, along with critical review articles spanning multidisciplinary subjects. We hope it serves to inform and inspire further research in flexible and smart electronics, as well as to guide strategies for the future development of advanced semiconductors and devices.

The third theme of this Special Issue encompasses articles focused on integrated and multimodal sensory systems constructed on flexible platforms. Yin et al. provide a comprehensive review of wearable electronic systems designed for monitoring heart rate variability, emphasizing their applications in predicting both physical and mental well-being^[14]. Wang et al. discuss recent advancements in artificial intelligence-enhanced multimodal sensor-integrated devices and systems, specifically targeting key IoT applications in autonomous driving, health monitoring, and robotics^[15]. Dai et al. introduce an innovative smart finger patch that combines magnetoelastic and resistive bending sensors, outlining its significant potential for applications in immersive human-machine interfaces, including virtual reality (VR) and augmented reality (AR) environments, as well as in medical diagnostics, smart manufacturing, and industrial automation^[16]. Chen et al. report on a straightforward electrospraying method for fabricating flexible lithium-ion batteries as power sources, thereby providing strategies for the realization of fully flexible electronic systems^[17].

In the second theme focusing on neuromorphic sensory devices, Li et al. present a flexible artificial vision computing system utilizing FeO_x optomemristors, which facilitates complex and dynamic analog signal processing, including applications in speech recognition^[9]. Xu et al. introduce a bipolar graphene/F6CuPc synaptic transistor that mimics multiplexed neurotransmission, thereby constructing a complementary neural network for neuromorphic computation^[10]. Qian et al. report on an artificial self-powered and self-healable neuromorphic vision skin, which incorporates a silver nanoparticle-doped ionogel heterostructure as a photoacceptor. This innovative design demonstrates the ability to sense and memorize a variety of light patterns^[11]. Cheng et al. provide a comprehensive review of neurotransmitter-mediated artificial synapses based on organic electrochemical transistors, offering insights into the future development of biomimetic and bioinspired neuromorphic systems^[12]. Furthermore, Shao et al. review the current state of artificial sensory neurons, contributing both fundamental and practical insights necessary for the advancement of complete neuromorphic systems^[13].