Piezoelectric MEMS-based wideband energy harvesting systems using a frequency-up-conversion cantilever stopper

Two MEMS-based piezoelectric energy harvesting (EH) systems with wideband operation frequency range and capability of converting random and low-frequency vibrations to high-frequency self-oscillations have been proposed. In the first EH system (EH-I), by incorporating a high-resonant-frequency (HRF) cantilever as a frequency-up-conversion (FUC) stopper, the vibration amplitude of a low-resonant-frequency (LRF) cantilever with a resonant frequency of 36 Hz is suppressed and the operation bandwidth is increased to 22 Hz at 0.8g. The HRF cantilever is then triggered to vibrate at 618 Hz. In the second EH system (EH-II), by employing a straight cantilever as the FUC stopper, the operation frequency range of a meandered cantilever which responds to lower frequency vibration is further moved downward from 12 Hz to 26 Hz, and the voltage and power generation are significantly improved. The peak-power densities of the EH-II system are 61.5 mu W/cm(3) and 159.4 mu W/cm(3) operating at relatively lower operation frequencies of 20 Hz and 25 Hz at 0.8 g, respectively. (C) 2012 Elsevier B.V. All rights reserved.