Design and experimentation of meandered low frequency broadband piezoelectric energy harvester with resonant tuning

Abstract

In this work, a novel meandered 6DoF stepped beam energy harvester that can operate over a broad frequency range is proposed. The hybrid structure has regular beams and zigzag sections that promote greater deformation and bending. The reduced width section in the middle of the beam maintains a low resonance bending frequency and creates a concentrated stress structure. The placement of the piezoelectric layer in this region results in a high-power density. It is found to be a favorable structure to develop using standard microfabrication techniques compared to other broadband harvesters. Also, it can withstand higher mechanical stress and deformation. The proposed structure exhibits wide band characteristics at low frequency and generates higher power output against an array of cantilevers for a given area. The numerical analysis was carried out to select the optimal proof mass that would result in resonance frequencies closely spaced together and yield high output power. Experimental validation on a prototype subsequently confirms the accuracy of the frequency response predicted by the models. When tested under harmonic base excitation of 0.35 g, the harvester generates an average DC power of 374 $\mu \mathit{W}$ including signal conditioning losses in the frequency range of 12–27 Hz. The proposed structure offers excellent design flexibility to adjust resonant frequencies by varying the number of beams, the shape of the stepped section, and the proof mass of individual beams. Thus, it has the potential to generate sufficient power output from wideband, low frequency, and low amplitude vibration sources and can be easily optimized for a specific application.