Two Mechanical Tuning Schemes to Improve the Bandwidth of Electret-based Electrostatic Energy Harvester

In this paper, we propose two mechanical schemes with stop structures to improve the bandwidth of electrostatic energy harvester (e-VEH) which is based on an out-of-the-plane gap closing scheme. Firstly, we study the broadband performance of the single resonant e-VEH with package shell at low air pressure. It is found that under the acceleration of 1.8m/s2, the bandwidth is increased to 30 Hz at the pressure of 4 Pa. Also, a novel dual resonant structure has be proposed to broaden the bandwidth of e-VEH. In this new dual resonant e-VEH, there will be a mechanical coupling when the collision occurs between the two movable proof masses. This collision phenomenon will contribute to the high output between the two resonant frequencies, thus a broad operating bandwidth will be achieved at atmosphere.