Design optimization in geometry of seismic mass for MEMS based cantilever type piezoelectric energy harvester for motor vibrations

Abstract

Piezoelectric energy harvesters are suitable for vibration energy harvesting due to simple design, operation and fabrication in MEMS technology. Cantilever structures fixed from one end and seismic mass at the other must tune to different resonance frequency to ensure wideband frequency operation. Adequate width to length ratio of cantilever is required to avoid curling of cantilevers (bending). Effect of increase in width of the cantilever structure on resonance frequency has been investigated and also compared analytically in this paper. An optimized design has been proposed which compensates for the increase in resonance frequency due to increase in width by changing the geometry of the seismic mass. With the change in geometry of seismic mass a shift in center of mass has been achieved towards the free end of the cantilever which reduces the resonance frequency which is desirable. The design optimization of seismic mass reported in this paper reduces the resonance frequency by 4.27 % which is appreciated as it is required to harvest ambient vibrations having low frequency.