Fluid Sensor Based on Humidity- Responsive Fiber Zinc–Air Battery

Fluid sensing can realize noninvasive measurement and provide continuous, real-time physiological information, which shows great potential in the field of precision medicine. However, developing efficient, sensitive, convenient fluid sensors has become the key research direction at present. This study introduces a unique wearable fiber Zinc-air battery (ZAB) with a humidity response and liquid monitoring properties. The battery features a eutectic gel polymer serving as not only the battery electrolyte but also the induction element for humidity response and liquid monitoring. Besides, the gel electrolyte exhibits high water retention with a high electrolyte retention rate of 94.2% in a dry environment, as well as outstanding mechanical strength with a fracture strength of 16.1 kPa and elongation at break of 541%. Moreover, the structural flexibility of the battery allows it to withstand complex deformation, and the good conformal properties of the eutectic gel electrolyte exhibit excellent durability. Surprisingly, the fiber ZAB can be successfully woven into the fabric to provide a stable power supply for a small digital watch, and the fiber battery can also respond to the amount of urine in the diaper. This study provides an idea for wearable physiological monitoring.