Numerical and experimental investigation of an auxetic piezoelectric energy harvester with frequency self-tuning capability

To deal with the limited availability of long-lasting power sources for sensor nodes in industrial environments, a novel piezoelectric energy harvester with high efficiency and a wide working bandwidth was designed to harvest broadband and random vibrations from the ambient environment. The developed energy harvester adopts a doubly clamped piezoelectric beam with a peanut-shaped auxetic structure to improve the power output. It also incorporates a sliding proof mass for frequency self-tuning, enabling a wider working bandwidth. As the doubly clamped beam exhibits geometry nonlinearity under large vibration amplitudes, the power output of the energy harvester can be further enhanced in the frequency self-tuning process. Finite element simulations are conducted to evaluate the impact of the auxetic structure and the position of the proof mass on the performance of the energy harvester. Experiments are performed to examine the energy harvesting performance of the proposed energy harvester. Under an excitation acceleration of 0.3 g, the use of the sliding proof mass widens the working bandwidth of the auxetic energy harvester (AEH) by 9 Hz, with the maximum root mean square output power of AEH reaching 18.78 μW, which is much higher than that of the plain energy harvester (PEH) or the AEH with a fixed proof mass. The developed energy harvester can successfully power a wireless temperature and humidity sensor node based on the vibration produced by a centrifuge, which demonstrates the practical feasibility of the proposed energy harvester for industrial applications.

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