Copper foil-type vibration-based electromagnetic energy harvester

Abstract

This paper presents the modeling, simulation, fabrication and experimental results of a vibration-based electromagnetic power generator (EMPG). A novel, low-cost, one-mask technique is used to fabricate the planar coils and the planar spring. This fabrication technique can provide an alternative for processes such as lithographie galvanoformung abformung (LIGA) or SU-8 molding and MEMS electroplating. Commercially available copper foils of 20 μm and 350 μm thicknesses are used for the planar coils and planar spring, respectively. The design with planar coils on either side of the magnets provides enhanced power generation for the same footprint of the device. The harvester's overall volume is 1 cm3. Excitation of the EMPG, at the fundamental frequency of 371 Hz, base acceleration of 13.5 g and base amplitude of 24.4 μm, yields an open circuit voltage of 60.1 mV, as well as 46.3 mV load voltage and 10.7 μW power for a 100 Ω load resistance. At a matching impedance of 7.5 Ω the device produced a maximum power of 23.56 μW and a power density of 23.56 μW cm-3. The simulations based on the analytical model of the device show good agreement with the experimental results. © 2010 IOP Publishing Ltd.