Tapered substrate thickness to enhance the performance of a piezoelectric energy harvester

Abstract

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