Self‐Powered Switchable Gas‐Humidity Difunctional Flexible Chemosensors Based on Smart Adaptable Hydrogel

Abstract The development of self‐powered, flexible, and multi‐function sensors is highly anticipated in wearable electronics, however, it remains a daunting challenge to identify different signals based on a single device with singular sensing material without algorithmic support. Here, a smart adaptable hydrogel is developed by co‐introducing two ions with vastly different hydrophilicity for the construction of an electrochemically self‐powered, flexible, and reversibly switchable difunctional chemosensor with a metal‐air battery structure. The prepared hydrogel can readily switch between water‐rich and water‐deficient states for crosstalk‐free detection of oxygen and humidity respectively, since O 2 gas and water molecules can directly participate in the oxygen reduction reaction in the device and act alone as limiting reactants and catalysts to affect the reaction rate under different hydrogel states. The resulting sensor demonstrates breakthrough O 2 and humidity sensing performance with sensitivities as high as 4170.5%/% and 380.2%/% RH in water‐rich and water‐deficient states, respectively, and ultrawide detection ranges. Thanks to these, the devices can be applied for real‐time and remote monitoring of ambient oxygen, transcutaneous oxygen pressure changes, respiration, and skin moisture by combining with wireless communication technology, and therefore have important application prospects in the fields of safety, health management, and non‐contact human‐machine interaction.