Investigation of mechanical nonlinear effect in piezoelectric MEMS vibration energy harvesters

Abstract

Abstract Nonlinear resonance in piezoelectric vibration energy harvesters (pVEHs) has a large effect on the characteristics of power generation. In this study, the origin of nonlinearity was investigated on MEMS pVEHs using a 3-µm-thick-Pb(Zr,Ti)O 3 film. The resonant frequency and mass of the pVEHs were 180.6 Hz and 3.63 mg, respectively. From the resonance curves of the output voltage and tip displacement measured at a low acceleration, where linear resonance was obtained, the electromechanical coupling and mechanical quality factors of the pVEHs were determined to be 0.3% and 430, respectively. Although the high output power density of 4.1 µW·mg −1 ·G −2 was obtained at the acceleration of 0.024 G, the effect of nonlinear resonance appeared and suppressed the output power density at the acceleration of 0.07 G and more (G is the gravitational acceleration). The comparison between the results of experiment and numerical analysis using an equivalent circuit model revealed that the nonlinear damping effect has a larger contribution than a nonlinear spring on the suppression of the output power density at a high acceleration.