A Piezoelectric Energy Harvester Based on Pressure Fluctuations in Kármán Vortex Street

We have developed a n ew energy harvester for harnessing energy from the Karman vortex street behind a b luff body in a water flow. I t converts flow energy into electrical energy through oscillation of a piezoelectric film. Oscillation of the piezoelectric film is induced by pressure fluctuation in the Karman vortex street. Prototypes of the energy harvester are fabricated and tested. Experimental results show that an open circuit output voltage of 0.12 pp V and an instantaneous output power of 0.7 nW are generated when the pressure oscillates with an amplitude of ~0.3 kPa and a frequency of ~52 Hz. This approach has the potential of converting hydraulic energy into electricity for powering wireless devices. The low output power of the device can be improved by an optimization design procedure or by adopting a p iezoelectric material with higher piezoelectric constants. A n array of these devices with multiple resonant frequencies may be considered for energy harvesting from ambient flow sources.