Modeling and evaluation of d33 mode piezoelectric energy harvesters

A microfabricated d(33) mode piezoelectric energy harvester (PEH) with unimorph cantilever structure patterned by interdigital electrodes was designed, fabricated and analyzed. New analytical expression for estimating output power was developed based on the modification of conformal mapping and Roundy's analytical modeling. The results using the new analytical equation can explain the effects of electrode design on the output power of d(33) PEH. The output power increases with a longer finger width to a certain limit, and then decreases presumably due to depoling and polarization reversal by charge injection and charged defects in a piezoelectric layer.