Water droplet-driven and perforated conducting polymer composite energy harvester: platform for powering portable and wearable electronics

A major challenge for portable and wearable systems is reliable delivery of electrical power without use of external power supply. Herein, we exploit water droplets to produce electricity in the form of portable or wearable devices to operate electronic systems. An active polymeric layer composed of PVA [poly(vinyl alcohol)] with PSSA [poly(4-styrenesulfonic acid)] (a proton source) and PSSA-MA [poly(styrene sulfonic acid-<i>co</i>-maleic acid)] (cross-linking agent) is employed to charge the supercapacitor. By water absorption and ion diffusion, the energy conversion device reliably generates a DC output for long-term period. The Output performance of combined devices were simply increased up to 1.8 V in serial connection and 1.2 mA in parallel connection. Finally, the device is capable of storing electrical energy using supercapacitors of 220 mF up to 3.2 V, delivering power to a 60 mW practical device. This highlights the potential of a water-induced innovative power supply technology that is able to be integrated with the human body in portable and wearable forms for driving sensors and small electronics.