Piezoelectric energy harvester enhancement with graphene base layer

Abstract

Traditional power source often becomes an obstacle for microelectromechanical systems (MEMs) from further miniaturization. Piezoelectric energy harvester serves as a perfect alternative power source which is clean and able to embed with MEMs. In this work, we replace silicon support layer in piezoelectric cantilever beam with nanocrystalline graphene (NCG) and compare their performance. By using finite element simulations, a cantilever beam piezoelectric energy harvester with nanocrystalline graphene as base layer with different thickness is modeled. For a better understanding on its performance, we had performed frequency response analysis for each design. The thickness of substrate layer and piezoelectric layer is varied from 50 nm to 400 nm. From the result, it is shown that higher thickness gives better Q-factor and figure of merit (FOM). Furthermore, graphene-based energy harvester had increase the operation bandwidth of energy harvester compared to silicon. For example, a 200 nm of ZnO layer and graphene layer gives a Q-factor & FOM of 3.4 times higher than silicon and a larger bandwidth by a factor of 1.1. In general, it is shown that the replacement of silicon with graphene had reduced energy loss by improving the efficiency of mechanical energy transfer in piezoelectric energy harvester.