Optimal design of a unimorph piezoelectric cantilever devoted to energy harvesting to supply animal tracking devices

Abstract

This paper presents the mechanical structure optimization of a piezoelectric energy harvesters devoted to supply embedded animal tracking devices. The harvester mechanical structure being a bilayer unimorph piezoelectric cantilever is composed of two elements: a piezoelectric layer and a non-piezoelectric layer (i.e, active and passive layers). The suggestion of this paper is to find the optimal ratio between their two thicknesses in order to maximize the output recuperated voltage at the electrodes. For that, from the model that links the mechanical excitation moment and the output electrical charge, a gradient-based optimization is carried-out. Comparison with existing mechanical piezoelectric harvester structure is made and which clearly demonstrates that the proposed structure permits to gain up to five-times in terms of the output charge and a significant gain in terms of output electrical power for the same condition.