Hybrid vibration energy harvesting based on piezoelectric polyline beams with electret coupling

Aiming at harvesting vibration energy more efficiently, a hybrid energy harvester is proposed, which integrates the piezoelectric and electrostatic effects. It is composed of two piezoelectric polyline beams and an electret film. The two piezoelectric polyline beams stand closely, of which one is covered by an electret film, while the other is covered by a counter-electrode. Under base excitations, the electret film interacts with the electrode, by which the two polyline beams can excite each other and form a broad frequency band of large vibration, thereby generating a large output. The dynamical equations are derived and the simulations are carried out. For validation, the experiments are conducted. The experimental results prove that the hybrid harvester is more efficient in harvesting stochastic vibration energy. For PSD = 0.0041 g²/Hz, the two piezoelectric polyline beams can generate the power outputs of 47.9 and 23.6 µW, respectively.