Investigation of Using Free-Standing Thick-Film Piezoelectric Energy Harvesters to Develop Wideband Devices

This paper is concerned with the wideband behavior of single-frequency and multi-frequency free-standing thick-film piezoelectric energy harvesters. The energy harvesting devices have been fabricated and brief fabrication information is provided. The individual harvesters have been combined with either symmetric or asymmetric tip masses, with some being connected together to form a harvester array. Testing has been undertaken using harmonic vibrations with a wide range of frequencies and accelerations, and also using a random machinery vibration, and data have been recorded in terms of un-rectified and rectified open-circuit voltage, output power with matched resistive loads, peak-to-peak tip displacement, and even charging rates of capacitors. As a general result, the individual harvesters with asymmetric tip masses have vibrated nonlinearly below and in the vicinity of the resonant frequencies. An individual harvester vibrating at the resonant frequency with 0.5 g acceleration has been able to charge a 1000 μF capacitor to 1 V within 12 min and to 1.5 V within 30 min. Also, the harvester array has exhibited a wideband response, where an open-circuit voltage of above 0.8 V has been provided within a certain range of frequencies. Finally, the harvester array has successfully charged a capacitor on a vibrating test sieve shaker, proving the feasibility of the proposed device in real applications.