Charge redistribution in piezoelectric energy harvesters

Piezoelectric energy harvesting cantilevers provide a simple, compact low cost construction method for energy harvesting from vibrational sources. Beam theory predicts a linear distribution of strain along the length of the beam, but the conversion of this strain to electrical energy is dependent on the coverage of the beam with active material. In this paper, we demonstrate how re-distribution of charge within the piezoelectric leads to losses that can be as high as 25% of the potential generated power. Reducing the area coverage of the piezoelectric is shown to significantly improve cantilever power output, with the optimum coverage being 2/3. [doi:10.1063/1.3685701]