Characterization of piezoelectric MEMS vibration energy harvesters using random vibration

Abstract

In this study, we fabricated piezoelectric MEMS cantilever-type vibration energy harvesters employing Pb(Zr,Ti)O3 films, which were designed to exhibit a resonant frequency of around 185 Hz. The output power was investigated under random vibration whose power spectral density (PSD) was constant in the frequency regime between 150 and 220 Hz. The PSD of the output power shows that the cantilever vibrates at the resonant frequency of around 183 Hz, and that the resonant frequency decreases and the full-width at half maximum increases with increasing vibrational acceleration. In comparison with the measurement results under sinusoidal vibration, it was clarified that this phenomenon is caused by the soft spring effect due to the nonlinearity of the cantilever vibration. The power generation under random vibration is proportional to the square of the acceleration not only in the linear region but also in the nonlinear region.