A three-ports structure for electrostatic energy-harvester to lower constraint force and to enhance fast storage

In this paper, we discuss on a new method to increase the output current of energy-harvesting device by using a symmetric three-ports electrostatic comb-drive mechanism that enables fast charging of battery. A symmetric electrodes layout is used to reduce the binding electrostatic force that constraints the movable electrodes, thereby allowing a formation of a high electret potential without electrostatic collapse. The output short-circuit current is increased by 2.8 times by increasing the electret potential from the -120 V to -300 V. At the same time, the output impedance is also decreased 5 MΩ. The lowered constraint force enables energy harvester operation at a low acceleration range of 0.1 G or less.