Enhanced performance of electrostatic energy harvester with integrated opposite-charged electrets

This paper presents a novel electrostatic vibration energy harvester with two opposite-charged-electret design for enhanced output performance. The device consists mainly of three parallel silicon plates. The middle plate of spring-mass resonant system is double-side patterned with electrodes. The negatively and positively charged electret plates are located on the bottom and top positions, respectively. Therefore, when the movable mass reaches its highest and lowest positions, maximum charge can be induced at both extremes. These are superior to the traditional two-plate configuration where maximum charge can only be created at lowest position of seismic mass. As a proof of concept, an electret-based energy harvester (e-VEH) has been designed and fabricated. Experimental results demonstrate the output voltage increases by 18.6% and 80.9% compared to the bottom electret alone and top alone configurations, respectively. This research provides a simple and effective method for improving the performance of e-VEHs.