A new S-shaped MEMS PZT cantilever for energy harvesting from low frequency vibrations below 30 Hz

In this paper, a new S-shaped piezoelectric PZT cantilever is microfabricated for scavenging vibration energy at low frequencies (<30 Hz) and low accelerations (<0.4g). The maximum voltage and normalized power are 42 mV and 0.31 μW g ⁻², respectively, at input acceleration of 0.06g. For acceleration above 0.06g, the vibration of PZT cantilever changes from a linear oscillation to a nonlinear impact oscillation due to the displacement constraint introduced by a mechanical stopper. Based on theoretical modeling and experimental results, the frequency broadening effect of the PZT cantilever is studied with varying stop distances and input accelerations. The operation bandwidth of the piezoelectric PZT cantilever is able to extend from 3.4 to 11.1 Hz as the stop distance reduces from 1.7 to 0.7 mm for an acceleration of 0.3g, at the expense of the voltage and normalized power at resonance decreasing from 40 to 16 mV and from 17.8 to 2.8 nW g⁻², respectively.