An electret-based electrostatic /spl mu/-generator

This paper proposes a new approach towards mechanical waste energy scavenging, using a micromachined electrostatic converter. The device consists of a vibration sensitive variable capacitor polarized by an electret. The variation of the capacitance results in a current through a load circuit. A physical model of the device is described; in order to obtain a closed form expression for the converted power a linear model is presented. This model shows that 50 /spl mu/W can be generated with a 5 /spl mu/m vibration. A first prototype design based on SOI MPW-service is proposed.