Generation of electrical energy using short piezoelectric cantilevers in flowing media

The power supply of wireless sensor systems is an issue of growing importance since replacement of batteries is very expensive over the sensor lifetime. An energy harvesting system which generates electrical energy from flowing media without any rotating parts will be presented. The harvester consists of piezoelectric cantilevers which oscillate in a media flow and convert kinetically energy into electrical energy. A model of the harvester was developed and the influence of geometrical parameters was simulated. Important design information was achieved as result of the simulation. Several harvester systems were built up using commercially available and not optimized PZT ceramic plates. Measurements were carried out in wind and water channels. It was found that the output voltage of the harvesters increase with the streaming velocity of the media. An output power of about 0.1mW was achieved at power adjustment in air. Optimized harvesters could deliver an up to two orders higher output.