A Leaf‐Inspired Self‐Powered Humidity Sensor With Enhanced Voltage Output and Rapid Response/Recovery

ABSTRACT With the rapid development of the Internet of Medical Things (IoMT), non‐invasive technologies are receiving increasing attention. As a core component, humidity sensors are essential for real‐time monitoring of vital signs such as respiration and perspiration. However, most humidity sensors suffer from slow response/recovery dynamics, and a trade‐off often exists between response speed and output voltage. To address this problem, we have developed a unique leaf‐like microstructure for humidity sensing, constructed with a fibrous framework that serves as ion reservoirs and integrated with 2D GO. With the incorporation of ion reservoirs and the formation of an ultrathin GO membrane, the leaf‐like microstructure enables rapid water molecules and ion diffusion and controlled water penetration, achieving a fast response time of 0.64 s, a recovery time of 0.84 s, and a high output voltage of 0.96 V, which substantially surpass existing self‐powered humidity sensors. Moreover, density functional theory (DFT) simulations reveal that the introduction of ion reservoirs reduces the adsorption energy of protons, thereby facilitating ion migration on GO. Beyond its practical value in environmental and physiological monitoring, this work provides a new paradigm for designing high‐performance humidity sensors, laying the foundation for next‐generation humidity sensors.