Flexible and Biocompatible Chitosan‐Based Hydrogel for Ambient Energy Harvesting

Recently, nanogenerators have ignited significant interest within the scientific realm owing to their considerable potential for extracting energy from the surroundings. One promising method involves utilizing moisture from the environment as a source of energy for compact devices, which only require minimal electricity consumption. In this work, we demonstrated a chitosan/glycerol (CS/G) hydrogel‐based electric nanogenerator (HENG) with promising electric and mechanical performance. Specifically, a sole generator unit could produce an open‐circuit voltage of 1.1 V and a current density of 1 mA cm ⁻² , with a maximum power density reaching 0.26 mW cm ⁻² . The outstanding performance was attributed to the enhanced water absorption of the optimized hydrogel layer and the redox reaction at the top electrode. Additionally, a facile printing technique was introduced to make mass fabrication possible. Large‐scale integrated HENG arrays with high current (~100 mA) and voltage output (~100 V) were successfully demonstrated through serial and parallel connections, capable of directly powering wireless LED and motor propellers. A battery‐free wearable multisensing wristband was designed to demonstrate the real‐world application of HENG. This work presents a novel pathway for advancing the creation of self‐sustainable, flexible applications, demonstrating significant potential for the forthcoming age of wearable technology and the Internet‐of‐Things.