An Impact-Coupled MEMS Electrostatic Kinetic Energy Harvester and Its Predictive Model Taking Nonlinear Air Damping Effect Into Account

This paper describes a predictive and complete numeric model of a multi-mass and impact-coupled MEMS electrostatic kinetic energy harvester (e-KEH). A silicon resonator is coupled with elastic silicon beams (acting as a part of stoppers) and a miniature metallic ball. The model considers all these impacts as well as the electromechanical force and catches the frequency-up and spring-softening effects. More importantly, for the first time, it models accurately the evolving and non-linear squeeze-film air damping effect in a gap-closing transducer, which is induced by the large amplitude of displacement of the silicon mass. The predictions provided by the model are compared with experimental results, showing a good consistency. The key parameters of the KEH are analyzed with the proposed model, which can be of great help for further design optimization of similar devices. [2018-0174]