Surface Micromachined MEMS Capacitors With Dual Cavity for Energy Harvesting

A novel electrostatic MEMS capacitors array with dual capacitive cavities for energy harvesting from environmental vibration has been developed. This paper presents the new design, fabrication, modeling, and complete set of characterization of a MEMS capacitors array energy harvester with dual cavities, which achieves considerably higher energy generation than similar devices with a single capacitor. Rocking instability, that is, perturbations that may result in movable plates not in parallel to fixed plates, of the movable plate has been studied based upon comprehensive dynamic simulations using MATLAB. Resultant symmetric breaking causes drastic reduction on power generation. The devices have been successfully fabricated using surface micromachining technology and experimentally characterized. The resonance frequency is observed at 500 Hz. A maximum power of 2.5 μW across the load resistors is achieved under a high DC bias of 15 V and extremely intense excitation above 5 g. Detailed dynamic performance of the MEMS capacitors array energy harvester are presented in the paper. Experimental comparison between device with single capacitor and capacitors array are addressed.