Bistable PiezoMEMS Energy Harvester with varying Magnetic Configurations

Bistable energy harvesting devices using magnetic repulsive forces have demonstrated the capability of widening the bandwidth, but at the expense of decreasing power. This paper reports on experimental results combining repulsive and attractive magnetic force configurations on a PiezoMEMS cantilever device. The goal of the study was to determine if varying magnetic configuration could enhance power density while widening the bandwidth. The paper investigates both in-plane and out-of-plane magnetic configuration using an AlN-based PiezoMEMS device with an embedded powdered NdFeB magnet as the mass. Results for the out-of-plane configuration using combination of attractive and repulsive forces demonstrated a significant power increase from (0.56 $\mu$ W to 0.93 $\mu$ W) without significant loss in bandwidth compared to repulsive force configuration. Attractive force configuration demonstrated a significant increase in power (3.73 $\mu$ W) but with significant bandwidth reduction. Thus, controlling magnetic polarization can be used to tailor the bandwidth and power density requirements.