Emerging flexible artificial sensory systems using neuromorphic electronics have been considered as a promising solution for processing massive data with low power consumption. The construction of artificial sensory systems with synaptic devices and sensing elements to mimic complicated sensing and processing in biological systems is a prerequisite for the realization. To realize high-efficiency neuromorphic sensory systems, the development of artificial flexible synapses with low power consumption and high-density integration is essential. Furthermore, the realization of efficient coupling between the sensing element and the synaptic device is crucial. This Review presents recent progress in the area of neuromorphic electronics for flexible artificial sensory systems. We focus on both the recent advances of artificial synapses, including device structures, mechanisms, and functions, and the design of intelligent, flexible perception systems based on synaptic devices. Additionally, key challenges and opportunities related to flexible artificial perception systems are examined, and potential solutions and suggestions are provided.

Epidermal electronics have been developed with gas/sweat permeability for long‐term wearable electrophysiological monitoring. However, the state‐of‐the‐art breathable epidermal electronics ignore the sweat accumulation and immersion at the skin/device interface, resulting in serious degradation of the interfacial conformality and adhesion, leading to signal artifacts with unstable and inaccurate biopotential measurements. Here, the authors present an all‐nanofiber‐based Janus epidermal electrode endowed with directional sweat transport properties for artifact‐free biopotential monitoring. The designed Janus multilayered membrane (≈15 µm) of superhydrophilic‐hydrolyzed‐polyacrylonitrile (HPAN)/polyurethane (PU)/Ag nanowire (AgNW) can quickly (less than 5 s) drive sweat away from the skin/electrode interface while resisting its penetration in the reverse direction. Along with the medical adhesive (MA)‐reinforced junction‐nodes, the adhesion strength among the heterogeneous interfaces can be greatly enhanced for robust mechanical‐electrical stability. Therefore, their measured on‐body electromyography (EMG) and electrocardiography (ECG) signals are free of sweat artifacts with negligible degradation and baseline drift compared to commercial Ag/AgCl gel electrodes and hydrophilic textile electrodes. This work paves a way to design novel directional‐sweat‐permeable epidermal electronics that can be conformally attached under sweaty conditions for long‐term biopotential monitoring and shows the potential to apply epidermal electronics to many challenging conditions.