Piezoelectric vibration energy harvesters have attracted much attention in the last decades due to their great potential application in powering various ultra-low-power sensors/actuators in the ambient environment. Many works have been presented to improve the energy conversion efficiency and broaden the operating bandwidth. One purpose of these studies is to harvest vibration energy with a specific excitation direction. However, a vibration source in a practical environment may from different directions. In this article, a piezoelectric vibration energy harvester with the radially distributed piezoelectric array is proposed to scavenge two-dimensional vibration energy. Meanwhile, we introduce a new concept, named angle bandwidth, to describe the ability of harvesting two-dimensional vibration energy. The theoretical analysis and the simulation results indicate that this harvester can scavenge vibration energy with arbitrary in-plane directions using the arc-shaped radially distributed piezoelectric array on a flexible cylinder. The experimental results show that this new design has large angle bandwidth, and the angle bandwidth increases from 87.5° to 106.3° when increasing the number of polyvinylidene fluoride elements from one to four. Also, the angle bandwidth of piezoelectric array in series is always larger than that in parallel. Overall, the present two-dimensional piezoelectric vibration energy harvester has the potential for a higher multi-directional vibration energy harvesting efficiency than a traditional cantilever-shaped piezoelectric vibration energy harvester. It also can be used as a self-powered vibration direction sensor.
High-temperature property of flexible polyvinylidene fluoride/(Na0.5K0.5)NbO3 vibration energy harvester
