Advancing Reverse Electrowetting‐on‐Dielectric from Planar to Rough Surface Electrodes for High Power Density Energy Harvesting

Abstract

Reverse electrowetting‐on‐dielectric (REWOD)‐based energy harvesting has been studied over the last decade as a novel technique of harvesting energy by actuating liquid droplet(s) utilizing applied mechanical modulation. Much prior research in REWOD has relied on planar electrodes, which by its geometry possess a limited surface area. In addition, most of the prior REWOD works have applied a high bias voltage to enhance the output power that compromises the concept of self‐powering wearable motion sensors in human health monitoring applications. In order to enhance the REWOD power density resulting from an increased electrode–electrolyte interfacial area, high surface area electrodes are required. Herein, electrical and multiphysics‐based modeling approaches of REWOD energy harvester using structured rough surface electrodes are presented. By enhancing the overall available surface area, an increase in the overall capacitance is achieved. COMSOL and MATLAB‐based models are also developed, and the empirical results are compared with the models to validate the performance. Root mean square (RMS) power density is calculated using the RMS voltage across an optimal load impedance. For the proposed rough electrode REWOD energy harvester, maximum power density of 3.18 μW cm−2 is achieved at 5 Hz frequency, which is ≈4 times higher than that of the planar electrodes.

Water Droplet‐Based Nanogenerators

“…[28] Besides surface engineering, some mechanism like modifying the electrodes can be an effective way to improve device efficiency. [29] Most of the droplet-based nanogenerators are fabricated in such a way that they are capable of operating in adverse conditions such as in high humidity surroundings or some abnormal weather conditions such as windy weather or high temperature than room temperature. Such independence in operation in adverse conditions is a great advantage over many conventional nanogenerators for the droplet-based nanogenerators.…”