Electrostatic Transducers for Micro Energy Harvesting Based on SOI Technology

This paper describes the modeling, fabrication, and characterization of SOI-based micro- electro-mechanical transducers used for energy harvesting. The electrostatic transducers convert vibrations of a seismic mass by means of variable capacitors realized using comb structures. The seismic mass with comb electrodes is suspended by four 1-mm-long straight beam springs. Transducers with springs of different widths with theoretical resonance frequencies ranging from 96 to 1160 Hz were realized. The frequency behavior of the resonators is investigated using an in-plane vibrometer with nm resolution. Linear and non-linear responses are measured for weak and hard driving excitations, respectively. The effect of the capacitance variation on the harvested power is investigated as well as the application of different resistive loads to the devices.