Enhancement of power output by a new stress-applied mode on circular piezoelectric energy harvester

Abstract

A new stress-applied mode is proposed on piezoelectric circular diaphragm energy harvester. Differing from the usual mode used in previous researches, the mass stick at the center of the diaphragm (PZT-51) is designed into an annular hollow shape. In this case, stress of the mass is applied along the edge of the copper sheet. A screw bonded with the undersurface of the diaphragm transfers force from the vibrator to the diaphragm. This device has a cylindrical shape and its volume is ∼7.9 cm3. With this new stress-applied mode, the piezoelectric energy harvester (with an optimal load of 18 kΩ, a mass of 30 g) could generate a maximum power output of ∼20.8 mW under 9.8 m·s-2 at its resonant frequency of ∼237 Hz. Meanwhile, the greater the hardness ratio between the ceramic and the copper sheet, the greater the advantages of the new structure.