Electrostatic Vibration Energy Harvester With a Self-Rechargeable Electret

The electrostatic vibration energy harvester (e-VEH) typically comprises a variable capacitor, whereas the electret layer provides a bias voltage during vibration. However, the charge stored in electret may significantly decay in high temperature or other harsh environments. Recovering the surface charge in electret without taking apart the brittle packaged device remains a technical challenge. In this work, e-VEHs are designed and fabricated with built-in silicon tips and perforated electrode based on MEMS technology. The integrated micro-tips could effectively recharge the electret surface without separating the assembled device. Through-holes on the fixed electrode also optimize the energy harvesting performance. After self-charging, the fabricated device yields an output voltage of 6.2 V at a low driving frequency of 75 Hz, suggesting promising applications for self-powered electronics.