Tapered substrate thickness to enhance the performance of piezoelectric energy harvester

Abstract

In this paper, the improvement of the performance of the piezoelectric (PZ) cantilever beam using the non-uniform substrate thickness has been presented. This reduces the resonant frequency, improves stress distribution and generates more output voltage and power. Both analytical and finite element method (FEM) analyses have been performed to investigate the effect of tapered substrate thickness on the PZ cantilever beam. The tapered substrate thickness has been used in rectangular and trapezoidal cantilever structures. All the designed cantilever structures have the same fabrication area, and their performance has been evaluated and compared using an excitation acceleration of 1g (9.8 m/s2). The tapered-down trapezoidal cantilever can achieve the minimum resonant frequency of 62.41 Hz, which is 48.83 % less than the resonant frequency of the uniform rectangular cantilever beam. The output peak voltage and average power of the proposed tapered-down trapezoidal cantilever beam are 12.36 V and 21 µW, respectively, which are improved by 44 % and 74.48 %, respectively to the uniform rectangular cantilever structure.