An electrostatic energy harvester exploiting variable-area water electrode by respiration

This paper reports an electrostatic energy-harvester exploiting water-layer formed by respiration as a variable-area electrode. We discover that electrically conductive water-layer is instantly formed on a silicon-dioxide surface by exhaled-breath. We adopt this layer as a variable capacitive electrode for electrostatic energy-harvesting. The capacitance change was anticipated using a theoretical modeling and finite-element-method (FEM) simulation, and theoretical power-generation was estimated (∼2 µW/cm² at 1 V). We then fabricated the prototype device and verified the capacitance change experimentally. Finally, the prototype showed charging and discharging characteristics by respiration successfully for being used as an energy-harvester driven by human-breath solely.