Multifunctionally moist-electric generator for self-powered ultra-fast sensing based on laterally dual gradient

Multifunctional self-powered sensors play a crucial role in various applications, ranging from body healthcare monitoring to environmental sensing. Herein, we developed a multifunctional moist-electric generator (MMEG), integrating energy harvesting, power supply and sensing in a single device. Two electrodes are on the same side of the poly (4-styrensulfonic acid) active film to construct a laterally dual gradient device The exposed areas of active film and the areas covered with electrodes naturally create a humidity gradient upon moisture, and meanwhile an ion gradient is generated on the surface of the active layer by asymmetric electrodes. The MMEG device has a small effective exposed film area of only 0.01×1 cm2 and provides a stable electrical output of 1 V and an unparalleled power density of 874 μW·cm−2 in humid environments. Due to good linear response and remarkable sensitivity (85700%), the MMEG is applied in self-powered humidity sensors of various scenarios, such as humidity sensors, respiration monitoring, non-contact sensing, sweat monitoring, and ultra-fast tactile sensing with a response time of 0.05 s. This work demonstrates a high-performance self-powered humidity sensing from self-humidity energy, rather than other energy types, and provides a general and effective strategy for the development of next-generation multifunctional self-powered devices.