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High-output piezoelectric energy harvester using tapered beam with cavity

Energy harvesting using cantilever-based piezoelectric structure is most popular for harvesting electrical energy from ambient vibrations. Efforts are also made to maximize the harvester power by means of tailoring the structural parameters of the cantilever beam. This article proposes a method to maximize the harvester voltage from the cantilever-based piezoelectric energy harvester by means of tailoring the structure of the cantilever, to have a tapering in width, thickness and in both width and thickness (double taper). It is also proposed to introduce rectangular and trapezoidal cavities in the tapered energy harvesters to further maximize the harvester voltage. The analytical model of the proposed harvesters is developed using Euler–Bernoulli beam theory, and its free vibration solution is analysed using Bessel functions. The energy harvesters are fabricated and experimentally evaluated for its performance. It is concluded from the results of analytical model and experimentation that width, thickness and double-tapered beam increases the harvester voltage by 35.6%, 84.8% and 126.6%, respectively, as compared to the energy harvester designed with uniform cantilever beam. Among all the energy harvesters proposed in this article, the maximum voltage is generated from the double-tapered beam with trapezoidal cavity. The experimental results are in close agreement with the results obtained from the analytical model.