A combined electrostatic-triboelectric vibration energy harvester

This paper presents a new combined electrostatic-triboelectric energy harvester. One of the practical limitations of Electrostatic Vibration Energy (EVE) harvesting technologies is the need for an initial priming voltage source. In the proposed scheme, the triboelectric effect is used to provide initial charges necessary for EVE harvester. This harvester converts vibration to electrical energy and stores it in two storage capacitors. The new harvester has a triboelectric part and an EVE part. The triboelectric part charges one of the storage capacitors and at the same time supplies necessary initial charge for EVE part which charges the other storage capacitor. In this way, charges generated by triboelectric part are fully transferred from it, which ensures best and continuous triboelectric charge generation. Without proper transfer of charges, the triboelectric part will saturate in few cycles of vibration. Thus, in the combined harvester both schemes aid each other. A prototype of the new harvester has been built and tested. The developed unit generated about 45 nW of power from a low frequency vibration source of 3 Hz.