Abstract
A vertical electret energy harvester has a problem of pull-in between electrodes. We proposed the harvester with spacer. Using the spacer, the surface potential of electret can be high because the spacer prevents the pull-in of electrodes. Therefore, the output power increased by the spacer. However, the change in electrostatic capacitance is decreased because the gap increases by the spacer. There is a trade-off relation between thickness of spacer and power. We evaluated the relation between surface potential of electret, thickness of spacer, and output power. Using a spacer with a thickness greater than 36 μm, the electrode can vibrate when the surface potential was −630 V. Moreover, the output power was maximum when the thickness of spacer was 36 μm.
