A curled PZT cantilever based MEMS harvester

A curled PZT cantilever based MEMS energy harvester using inter-digitally shaped electrodes was newly developed to generate high output voltage at a low resonance frequency from ambient vibrations. The curled piezoelectric cantilever was utilized to scavenge both vertical and longitudinal vibrations. It was comprised of polyimide, electrodes, PZT, and low stress silicon nitride layers and formed by using the intrinsic stress-induced bending deformation of a multi-layered cantilever. The inter-digitally shaped electrodes were employed for the d₃₃ piezoelectric mode operation and high output voltage. The polyimide was utilized as an elastic layer to decrease the resonance frequency of the harvester to below 200 Hz. The fabricated MEMS energy harvester generated the output voltage of 0.5 V and 1.08 V at its resonance frequency of 114.7 Hz under vertically and longitudinally induced small vibrations with acceleration of 2.3 m/s².