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.

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Flexible self-powered multifunctional sensing systems provide a promising direction for the development of wearable electronics. Although increased efforts have been devoted to developing self-powered integrated devices, the development of flexible and adaptable sensing systems with miniaturized stable power supplies is highly desirable yet greatly challenging. Herein, an ambient moisture-induced self-powered wearable sensing system was fabricated by integrating a porous polydopamine layer with a hydroxy group gradient (called g-PDA) based moisture-enabled power generator and a flexible pressure sensor. Due to the large amount of gradient-distributed free cations (H+) and locally confined anions produced in wide electrode spaces during hydration of the thin porous g-PDA film, the moisture-induced potential and effective output power density of the g-PDA-based power generator rapidly reaches up to 0.52 V and 0.246 mW cm–2, respectively. Importantly, the voltage output within 120 s only has 6% change, and a continuously open-circuit voltage can be maintained after 1900 s of attenuation, which is a breakthrough for the duration of humidity generation. Finally, a self-powered wearable multifunctional sensing system has been demonstrated to be able to provide real-time monitoring of human physiological signals, without an external power supply, which opens new opportunities for future self-powered multifunctional sensing systems.

Fast progress in material science has led to the development of flexible and stretchable wearable sensing electronics. However, mechanical mismatches between the devices and soft human tissue usually impact the sensing performance. An effective way to solve this problem is to develop mechanically superelastic and compatible sensors that have high sensitivity in whole workable strain range. Here, a buckled sheath–core fiber‐based ultrastretchable sensor with enormous stain gauge enhancement is reported. Owing to its unique sheath and buckled microstructure on a multilayered carbon nanotube/thermal plastic elastomer composite, the fiber strain sensor has a large workable strain range (>1135%), fast response time (≈16 ms), high sensitivity (GF of 21.3 at 0–150%, and 34.22 at 200–1135%), and repeatability and stability (20 000 cycles load/unload test). These features endow the sensor with a strong ability to monitor both subtle and large muscle motions of the human body. Moreover, attaching the sensor to a rat tendon as an implantable device allowes quantitative evaluation of tendon injury rehabilitation.

Restricted ambient temperature and slow heat replenishment in the phase transition of water molecules severely limit the performance of the evaporation-induced hydrovoltaic generators. Here we demonstrate a heat conduction effect enhanced hydrovoltaic power generator by integrating a flexible ionic thermoelectric gelatin material with a porous dual-size Al2O3 hydrovoltaic generator. In the hybrid heat conduction effect enhanced hydrovoltaic power generator, the ionic thermoelectric gelatin material can effectively improve the heat conduction between hydrovoltaic generator and near environment, thus increasing the water evaporation rate to improve the output voltage. Synergistically, hydrovoltaic generator part with continuous water evaporation can induce a constant temperature difference for the thermoelectric generator. Moreover, the system can efficiently achieve solar-to-thermal conversion to raise the temperature difference, accompanied by a stable open circuit voltage of 6.4 V for the hydrovoltaic generator module, the highest value yet.

A prominent challenge for artificial synaptic devices toward artificial perception systems is hardware redundancy, which demands neuromorphic devices that integrate both sensing and processing functions. Inspired by the biological visual and nervous systems, a novel flexible, dual‐modulation synaptic field‐effect transistor (SFET) is demonstrated in this work. The flexible SFET is constructed with zinc oxide nanowires and sodium alginate, which acts as the semiconductor layer and the gate dielectric, respectively. An excitatory postsynaptic current in this artificial synapse can be triggered by both electrical and ultraviolet stimuli as presynaptic spikes as a result of the electric double layer effect and the photoelectric effect. More importantly, through the co‐modulation of light and electric stimuli, the memory level of the artificial synapses can be tuned based on the transformation between short‐term plasticity and long‐term plasticity initiated by the gate voltage. Different voltages can modulate the memory retention levels of the optical inputs similar to the function of the optic nerve system. The underlying mechanisms for the SFET are investigated using Fourier transform infrared spectroscopy, photoluminescence, and X‐ray photoelectron spectroscopy. Overall, the devices provide a novel idea to mimic visual memory, showing a promising strategy for future electronic eyes.

Developing epidermal electronics for physiological signal monitoring, including human biopotential (electroencephalogram [EEG], [1,2] electrocardiogram [ECG], [3-6] and electromyogram [EMG] [7-9]) and vibration (pulsation [10,11] and voice [12,13]) signals, is of great importance for next-generation wearable medicine, human-computer interaction, and smart robot applications. In general, most reported flexible electronics exploit plastic or elastic matrices (PET, PI, PDMS, Ecoflex, parylene, etc.) with

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