Influence of design parameters on performance of piezoelectric MEMS energy harvesting

Abstract

The influence of design parameters of piezoelectric thin films on the performance of vibration-type piezoelectric energy harvesting devices is investigated experimentally. The devices have four layers of Pb(Zr,Ti)O3 thin films on a silicon-based microfabricated structure to obtain high output power. The initial deformation and output power are measured. The results indicate that the initial shape due to residual stress can influence the mechanical quality factor and output power, particularly for the low-acceleration regime. In addition, the influence of the weight of the mass is investigated by changing the weight of the harvester. It is experimentally demonstrated that the power density and the generative power’s ratio to the theoretical limit can be improved by increasing the weight. A very large value of the normalized power density, 55.45 mW cm−3 G−2 (1 G = 9.8 m s−2), is obtained when a tungsten mass is attached to the microfabricated harvesting device.