Field Enhanced Robust Droplet Electricity Generation

Abstract

Harvesting low grade hydrodynamic energy is attracting growing interest. Droplet generators have recently emerged as promising harvesting devices. However, toward practical utilization, their power density and energy conversion efficiency still warrant further improvement. In addition, the performance of droplet generators typically degrades when in contact with ambient water, significantly limiting their applications considering that they, by definition, are constantly exposed to water. This work reports a field-enhanced droplet electricity generator (FE-DEG) that significantly address these challenges. Using the field effect induced by a bias voltage to store high volumetric charge in the dielectric layer, the amount of charge that transfers during droplet impinging is significantly increased, which simultaneously improves the instantaneous power density and energy conversion efficiency. In addition, the performance of the generator can be reliably set by the external bias and remains stable after repeated immersion in bulk water, and even in some harsh chemical conditions. It is expected that this work may also inspire other robust energy harvesting devices.