High power piezoelectric energy harvester for a temperature monitoring system

Abstract

In this study, we present a lead-free, piezoelectric energy harvester capable of generating power in the milliwatt range. The harvester consists of four layers of polyvinylidene difluoride piezoelectric polymer, bonded to a cantilever with a tip mass. The cantilever’s resonance frequency was measured at 13.4 Hz. The piezoelectric layers are connected in parallel, resulting in a total capacitance of 27 nF. At resonance, under open-circuit conditions, the harvester generates nearly 90 Vpp when subjected to an acceleration of 1 g. When impedance is matched, the maximum power output reaches 2.4 mW. In addition, we integrated the harvester with commercially available signal conditioning cards, enabling conversion from an AC signal to a steady 3.3 V DC signal useful for electronics to evaluate their efficiency in charging a capacitor. Finally, we demonstrated the harvester’s functionality in an autonomous system that measures and displays temperature on a digital screen. The system operated autonomously for 6.5 h.