Electret-based microfluidic power generator for harvesting vibrational energy by using ionic liquids

Harvesting ambient vibrational energy for powering autonomous and mobile electronic systems is a challenge, which can be potentially met by microfluidics-based power generator. In this work, we propose a new microfluidic power generator (MPG) based on electret. By periodically compressing the microscopic conductive liquid bridge between two electrodes, the electrical power is generated. A simple electrical circuit model is developed for theoretical analysis. The experimental and theoretical results imply that the variation magnitude of the top contact area and the surface charge density of the electret are the two critical factors in power generation, and the output power improves drastically with the two factors. Furthermore, this MPG uses the ionic liquid as the liquid media, which can continuously work well in the air under normal conditions and in the wide operating temperature range. By far, the prototype with just single ionic liquid bridge of 15 µL volume and the surface charge density of 0.167 mC/m 2 can generate the maximum effective power of 0.221 µW and the energy per cycle of 7.48 nJ.