Effect of shape of seismic mass on potential generated by MEMS-based cantilever-type piezoelectric energy harvester

Abstract

A vibration-based piezoelectric energy harvester has received increasing attention as a potential power source for microelectronics because of its simplicity of design, operation, and fabrication of devices using microelectromechanical system (MEMS) technology. Energy harvesting provides unending sources of energy for low-power electronics such as wireless sensor nodes where replacement of batteries is not practically possible. Piezoelectric energy harvesters are widely considered because of their compact design, compatibility to MEMS devices, and ability to respond to a wide range of frequencies freely available in the environment. A model for cantilever-based piezoelectric energy harvester is designed and optimized by investigating the effect of seismic mass geometry on the potential generated. The effect of the shape geometry of the seismic mass on the resultant potential generated due to center of mass shift is calculated and compared. A seismic mass with a triangular-shaped geometry with fields concentrated at the tip of the triangle gives a resultant center of mass for a cantilever structure and the seismic mass at a higher point as compared with the rectangular or pyramidal shapes that were investigated. This shift in the center of mass of the combined geometry (cantilever beam and seismic mass) toward the applied pressure results in exerting a higher force and thus increasing the potential. This paper reports that an increased potential of 0.0533 V at a boundary load of 1 bar pressure (minimum feasible pressure) is generated by the energy harvester when a triangular-shaped seismic mass is used; this innovative shape is also compared with other geometries.