Energy harvesting from vibro-impact of structures using triboelectric materials

Abstract

In the past few years, the remarkable progress of wireless sensing technology has raised a huge demand for the miniature of electronics and distributed power supply strategies, which leads to tremendous attention to be focused on the energy harvesting techniques that generate continuous electricity from the ambient environment. There are several energy sources in nature for energy harvesting, such as solar, thermal gradient, wind/water flow and vibration. Among them, the wide existence of vibration makes it an ideal energy source to be harvested through transduction mechanisms. Triboelectricity has long been regarded as a negative effect until it was first utilized for energy harvesting in 2012. Triboelectric energy harvesters (TEHs) have a lot of merits including good flexibility, wide material availability, high power density and low cost. Therefore, it is worth investigating triboelectric energy harvesting for low-frequency vibrations and wind-induced vibrations energy harvesting, aiming at powering wireless sensors for infrastructure monitoring.In this thesis, a novel cantilever TEH working on the contact-separation mode is proposed for low-frequency vibration energy harvesting. An electromechanical model of TEH with non-parallel contact surfaces is derived by evaluating the total electrical energy between two surfaces. One merit of the proposed harvester lies in its simple design for easy implementation. The performance of TEH is investigated theoretically and experimentally, and the results show that it can harvest energy from not only low-frequency base excitation but also broadband vibration sources. A peak output voltage of 25 V is achieved from the harvester under a base acceleration of 0.5 g with an excitation frequency of 8 Hz. Good agreement is observed between the experimental results and analytical predictions. The performance of TEH can be improved by adjusting the gap distance between the top plate and the beam. The proposed TEH is shown to be cost-effective to scavenge the low-frequency vibration energy from the ambient environment.