INVESTIGATION OF MAGNETIC BISTABILITY FOR A WIDER BANDWIDTH IN VIBRO-IMPACT TRIBOELECTRIC ENERGY HARVESTERS

Mechanical energy from vibrations is widespread in the ambient environment. It may be harvested efficiently using triboelectric generators. Nevertheless, the harvesters\u27 effectiveness is restricted because of the limited bandwidth. This thesis proposed a comprehensive theoretical and experimental investigation of a variable frequency energy harvester, which integrates a Vibro-impact triboelectric-based harvester and magnetic nonlinearity to increase the operation bandwidth and improve the efficiency of conventional triboelectric harvesters. A cantilever beam with a tip magnet is aligned with another fixed magnet at the same polarity to induce a nonlinear magnetic repulsive force. A triboelectric harvester is integrated into the system by utilizing the lower surface of the tip magnet to serve as the top electrode of the harvester, while the bottom electrode with an attached Polydimethylsiloxane insulator is placed underneath. Numerical simulations are performed to examine the impact of the potential wells formed by the magnets. The structure\u27s static and dynamic behavior at varying excitation levels, separation distance, and surface charge density are all discussed. In order to develop a variable frequency system with wide bandwidth, the system\u27s natural frequency varies by changing the distance between the two magnets to reduce or magnify the magnetic force to achieve monostable or bistable oscillations. When the system is excited by vibrations, the beams will vibrate, which will cause an impact between the triboelectric layers. This impact will produce an alternating electrical signal through periodic contact-separation motions between the harvester\u27s electrodes. Theoretical findings were experimentally validated. The findings of this research have the potential to pave the way for developing an effective energy harvester capable of scavenging energy from ambient vibrations across a broad range of excitation frequencies. We enhanced the frequency bandwidth by 110.41 % compared to the conventional energy harvester. Combining magnetic nonlinearity and Vibro-impact can effectively broaden the operational frequency bandwidth and enhance the harvested energy for triboelectric energy harvesters

Magnetic Bistability for a Wider Bandwidth in Vibro-Impact Triboelectric Energy Harvesters

Mechanical energy from vibrations is widespread in the ambient environment. It may be harvested efficiently using triboelectric generators. Nevertheless, a harvester’s effectiveness is restricted because of the limited bandwidth. To this end, this paper presents a comprehensive theoretical and experimental investigation of a variable frequency energy harvester, which integrates a vibro-impact triboelectric-based harvester and magnetic nonlinearity to increase the operation bandwidth and improve the efficiency of conventional triboelectric harvesters. A cantilever beam with a tip magnet was aligned with another fixed magnet at the same polarity to induce a nonlinear magnetic repulsive force. A triboelectric harvester was integrated into the system by utilizing the lower surface of the tip magnet to serve as the top electrode of the harvester, while the bottom electrode with an attached polydimethylsiloxane insulator was placed underneath. Numerical simulations were performed to examine the impact of the potential wells formed by the magnets. The structure’s static and dynamic behaviors at varying excitation levels, separation distance, and surface charge density are all discussed. In order to develop a variable frequency system with a wide bandwidth, the system’s natural frequency varies by changing the distance between the two magnets to reduce or magnify the magnetic force to achieve monostable or bistable oscillations. When the system is excited by vibrations, the beams vibrate, which causes an impact between the triboelectric layers. An alternating electrical signal is generated from a periodic contact-separation motion between the harvester’s electrodes. Our theoretical findings were experimentally validated. The findings of this study have the potential to pave the way for the development of an effective energy harvester that is capable of scavenging energy from ambient vibrations across a broad range of excitation frequencies. The frequency bandwidth was found to increase by 120% at threshold distance compared to the conventional energy harvester. Nonlinear impact-driven triboelectric energy harvesters can effectively broaden the operational frequency bandwidth and enhance the harvested energy

Evaluating the biodeterioration enzymatic activities of fungal contamination isolated from some Ancient Yemeni mummies preserved in the National Museum

<p>screening fungal contamination of Anceint Yemeni mummy</p