Structural and Electrical Dynamics of a Grating-Patterned Triboelectric Energy Harvester with Stick-Slip Oscillation and Magnetic Bistability

The majority of research work on triboelectric energy harvesting is on material science, manufacturing and electric circuit design. There is a lack of in-depth research into structural dynamics which is crucial for power generation in triboelectric energy harvesting. In this paper, a novel triboelectric energy harvester with a compact structure working in sliding mode is developed, which is in the form of a casing and an oscillator inside. Unlike most sliding-mode harvesters using single-unit films, the proposed harvester utilizes grating-patterned films which are much more efficient. A bistable mechanism consisting of two pairs of magnets is employed for broadening the frequency bandwidth. A theoretical model is established for the harvester, which couples the structural dynamics domain and electrical dynamics domain. This paper presents the first study about the nonlinear structural dynamics of a triboelectric energy harvester with grating-patterned films, which is also the first triboelectric energy harvester integrating grating-patterned films with a bistable magnetic system for power performance enhancement. Theoretical studies are carried out from the perspectives of both structural and electrical dynamics. A comparison between the coupled model and uncoupled model reveals that the electrostatic force between the electrodes can be neglected. Great differences in structural response and electrical output are found between a velocity-dependent model and Coulomb’s model for modelling the friction in the harvester. The bistable mechanism can effectively improve the output voltage under low-frequency excitations. Additionally, the output voltage can also be obviously enhanced through increasing the number of the hollowed-out units of the grating-patterned films, which also results in a slight decrease of the optimal load resistance of the harvester. These findings enable innovative designs for triboelectric energy harvesters and provide fabrication guidelines in practical applications.

A STUDY OF DESIGN FLEXIBLE FORCE OUTPUT OF COMPLIANT BISTABLE MECHANISM WITH LIMITED SPACE

This paper reports a new compliant bistable micromechanism (BM) with the flexibility of force output under a space constraint. The mechanism has four Bézier curved beams and a shuttle mass at its center. Bézier curves offer high flexibility for design of beam shapes of BMs. Compared to the conventional BMs with cosine curved beams and slanted straight beams, the BM with Bézier curved beam can be designed to have smaller switching forces under the same device area and thickness.