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

A MEMS-based piezoelectric energy harvesting (PiezoEH) system is proposed and investigated not only with a wideband and steadily increased output voltage ranging from 50mV at 30Hz to 102mV at 52Hz, 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 36Hz and a top PZT cantilever (PZT-T) with high resonant frequency of 618Hz 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 22Hz nearby its resonant frequency of 36Hz. Meanwhile, the PZT-T is triggered and self-oscillated at 618Hz due to impact caused by PZT-B in each vibration swing of PZT-B. The maximum output voltage and power are 101mV and 0.011μW for the PZT-B, and are 11 1mV and 0.019μW for the PZT-T, respectively.