Design and Analysis of a Piezoelectric Vibration Energy Harvester Using Rolling Mechanism

In this paper, a novel piezoelectric vibration energy harvester using rolling mechanism is presented, with the advantage of harvesting more vibration energy and reducing the impact forces caused by the oscillation. The design utilizes an array arrangement of balls rolling the piezoelectric units, and a piezoelectric unit consists of a piezoceramic (PZT) layer and two raised metal layers bonded to both sides of the PZT layer. The rolling mechanism converts the irregular reciprocating vibration into the regular unidirectional rolling motion, which can generate high and relatively stable rolling force applied to the piezoelectric units. A theoretical model is developed to characterize the rolling mechanism of a ball rolling on a piezoelectric unit. And based on the model, the effects of structural design parameters on the performances of the vibration energy harvester are analyzed. The experimental results show that the rolling-based vibration energy harvester under random vibration can generate stable amplitude direct current (DC) voltage, which can be stored more conveniently than the alternating current (AC) voltage. The experimental results also demonstrate that the vibration energy harvester can generate the power about 1.5 μW at resistive load 3.3 MΩ while the maximal rolling force is about 6.5 N. Due to the function of mechanical motion rectification and compact structure, the rolling mechanism can be suitable for integrating into a variety of devices, harvesting energy from uncertain vibration source and supplying electric energy to some devices requiring specific voltage value.