PZT and PVDF piezoelectric transducers' design implications on their efficiency and energy harvesting potential

Abstract

Despite the intensive research carried out in the last two decades, the actual performance of piezoelectric energy harvesters needs significant improvement for widespread applicability. Custom designed experimental set-ups and methods can be applied for the evaluation of new piezoelectric energy harvesters or modified design versions of existing transducers, in terms of efficiency and specific power. In this context, two representative types of commercial cantilever piezoelectric transducers, made of PZT and PVDF material respectively, were tested in various combinations of aerodynamic and harmonic base excitation. A line type laser was used along with long exposure photography for the visualisation of the piezofilm's mode shapes, tip deflection and the digitization of the elastic line at the oscillation extrema. The harvested power was measured at on-resonance conditions and studied relative to the excitation combinations and the mode shapes. Energy conversion efficiency, defined as the ratio of the electric-field energy accumulated by the supercapacitors, over the total elastic strain energy change of the material during the oscillations is measured and compared. Design improvements are proposed for both transducer types to extract and absorb higher amounts of energy and improve their bandwidth to match the available excitation source characteristics. © 2022 Walter de Gruyter GmbH, Berlin/Boston 2022.