Vibrational Energy Harvesting Using a Unimorph with PZT- or BT-Based Ceramics

Abstract

Vibration-electrical energy converters based on the piezoelectric effect were investigated for energy harvesting and possible use in ultralow-power sensor modules. A patterned FRP plate was used as the base beam. PZT-based and BT-based ceramics were adhered to the FRP beam, and the unimorph structure was fabricated. The unimorphs were oscillated by vibration generator, and the generated voltage across load resistance was measured. The output voltages were proportional to g 31. The power and energy were closely related to g 31 2 or d 31 g 31/tanδ. The unimorph consisting of PZT with a higher Curie temperature produced larger power and energy. Mn-doping was also found to be effective for producing energy and power in BaTiO3-based ceramics. Two 18 × 10 × 0.5 mm unimorphs, consisting of PZT-based ceramics with a g 31 of 11.8 mV/N and Q m of 461, and lead-free Mn-0.2 mol% doped BaTiO3 ceramic with g 31 of 2.2 mV/N and Q m of 95.3, produced 1763 μJ and 432 μJ, respectively, by 45 second oscillation with a 0.8 mm displacement and a frequency of 80 Hz.