Harvesting ultrasonic energy using 1–3 piezoelectric composites

Harvesting longitudinal ultrasonic energy from the surroundings has been highlighted as an alternative to conventional batteries. The energy can be used to power portable electronics and wireless sensors operating at remote locations. In this paper, an ultrasonic energy harvester made of a 1–3 piezoelectric composite is proposed. This harvester could convert longitudinal-mode ultrasonic vibrations into electrical energy. A theoretical analysis of a 1–3 piezoelectric composite harvester operating with thickness-stretch modes is performed. The results show that maximum output power dissipated in the load can be achieved when the load resistor is equal to the impedance of the harvester. Under such conditions, two peaks of maximum output power occur at the antiresonance frequency and resonance frequency. An experimental study following the theoretical model confirms the feasibility of extracting certain amounts of ultrasonic vibration energy using a 1–3 piezoelectric composite harvester. Both the experimental and theoretical studies show that the output voltages for different pure resistive loads peak at different operating frequencies. As the pure resistive load increases, the operating frequency varies from the resonance frequency to the antiresonance frequency.