Improvement of effectiveness and output of electret energy harvester by symmetric comb-drive structures

Abstract

In this paper, we experimentally demonstrate a new method to improve the effectiveness of energy harvester that is based on solid-state electret. A symmetric three-ports electrostatic comb-electrode mechanism is used to reduce the binding electrostatic force that constraints the movable electrodes, thereby allowing a formation of a higher electret potential without electrostatic collapse. Two energy harvesters having different electret potentials are prepared to compare the harvester effectiveness and the electrical damping. The harvester effectiveness is increased by 4 times by increasing the electret potential from the -60 V to -250 V. At the same time, the electrical quality factor is also decreased from 700 to 500. Therefore, this new mechanism provides the energy-harvesting device for a wireless sensor node which can compatibly be made compact and can generate large output.