Electrostatic energy harvesting device with out-of-the-plane gap closing scheme

In this paper, we report on an electrostatic energy harvester with an out-of-the-plane gap closing scheme. Using advanced MEMS technology, energy harvesting devices formed by a four wafer stack are batch fabricated and fully packaged at wafer scale. A spin coated CYTOP polymer is used both as an electret material and an adhesive layer for low temperature wafer bonding. The overall size of the device is about 1.1 cm x 1.3 cm. At an external load resistance of 13.4 M Omega, a power output of 0.15 mu W is achieved when vibration at an acceleration amplitude of 1 g (similar to 9.8 m/s(2)) is applied at a low frequency of 96 Hz. The frequency response of the device is also measured and a broader bandwidth is observed at higher acceleration amplitude. (C) 2014 Elsevier B.V. All rights reserved.