Extending the bandwidth of Piezo-Electric energy harvesting through the use of Bias Flip

In this paper, we report three new results. 1) We show simulations of max output power from a Piezo-Electric (PZ) Energy Harvesting Device (EHD) as a function of frequency and Bias Flip (BF) efficiency. These simulations show that BF with 95% efficiency improves the 3dB BW by 4x. They also show that, at frequencies 30% above resonance (150 Hz) or below resonance (80 Hz), 95% BF efficiency improves output power by >15x (13.6 dB) compared to the case of no BF. 2) We experimentally demonstrate that 95% BF can be achieved on non-Piezo-Electric (non-PZ) capacitors. 3) We show that BF efficiency on PZ capacitors is lower than for non-PZ capacitors, and we relate this to the series resistance of the EHD at the BF frequency.