Investigation of piezoelectric MEMS-based wideband energy harvesting system with assembled frequency-up-conversion mechanism

Abstract A MEMS-based piezoelectric energy harvesting (PiezoEH) system is proposed and investigated not only with a wideband and steadily increased output voltage ranging from 50 mV at 30 Hz to 102 mV at 52 Hz, but also with the capability of converting random and low-frequency vibrations into high-frequency self-oscillations. The PiezoEH system consists of a bottom PZT cantilever (PZT-B) with low resonant frequency of 36 Hz and a top PZT cantilever (PZT-T) with high resonant frequency of 618 Hz packaged closely. By incorporating PZT-T and package base as top and bottom mechanical stoppers, the vibration amplitude of PZT-B is suppressed but the operation bandwidth is broadened to 22 Hz nearby its resonant frequency of 36 Hz. Meanwhile, the PZT-T is triggered and self-oscillated at 618 Hz due to impact caused by PZT-B in each vibration swing of PZT-B. The maximum output voltage and power are 101 mV and 0.011colonW for the PZT-B, and are 111 mV and 0.019colonW for the PZT-T, respectively.