Low-frequency vibration-based energy harvester using a piezoelectric composite beam

A composite beam based piezoelectric energy harvester (EH) is designed and characterized which can be used to harvest energy with low frequency vibrations. This kind of EH is demonstrated to be 3.12 times and 1.32 times (at 0.1g) more efficient at output power generation than a standalone piezoelectric bimorph and piezoelectric bimorph with a proof mass at the free end, respectively. The resonant frequency of the EH is reduced from 275 Hz (for standalone bimorph) to 36 Hz by using the soft spring. With the aid of spring hardening effect using a stopper, the operating bandwidth is increased from 5.25 Hz to 16.4 Hz.