2D Vibration based MEMS Energy Harvester

Abstract

Electrostatic energy harvester for two axis vibration is developed. It was fabricated by using silicon-glass anodic bonding and deep silicon etching. The device which generates energy from only one directional vibration has much different resonant frequency for each direction. To gain energy from two or more directional vibration the structure was designed to have equal resonant frequency along the x, y-axis by symmetric spring-mass structure. When the direction of ambient vibration is changed from x-axis to y-axis, the device still generates equal amount of energy. Resonant frequency of the structure is 191 Hz along the x-axis vibration direction. The device size is 9.0 mm×9.0 mm×0.6 mm. Vibration of which the acceleration is 1.2 m/s2 and the frequency is 191 Hz generates 0.73 µW/cm3 . Although vibration direction is not matched, power is generated more than 0.2 µW/cm3 at resonant frequency.