Electret-based electrostatic energy harvesting device with the MEMS technology

In this paper, we propose an electrostatic energy harvester with an out-of-the-plane gap closing scheme. Using advanced MEMS technology, two components of the energy harvesting device are fabricated from two silicon wafers. A spray coated CYTOP polymer is used both as an electrets material and an adhesive layer for low temperature wafer bonding. The overall size of the device is about 13 × 18 mm
²
. With an external load resistance of 16 MΩ, a power output of 4.04 μW is achieved when vibration amplitude of 1g (~9.9 m/s
²
) is applied at the resonant frequency of 155.8 Hz. The frequency response of the device is characterized and broader bandwidth is observed at higher acceleration amplitude due to the squeezed air damping. The response on random vibrations is also tested. An average power output of 2.22 μW is harvested when vibration is applied at random frequency in a range of 160 ± 12.5 Hz with RMS acceleration of 10.5 m/s
²
.