A Vibro-Impact Triboelectric Energy Harvester with Magnetic Bistability for Wide Bandwidth

Energy from mechanical vibrations is prevalent in the ambient, which can be effectively harvested using triboelectric generators. However, the efficiency of the harvesters is limited by the narrow bandwidth. Herein, we propose combining Vibro-impact and magnetic nonlinearity for Polydimethylsiloxane-based triboelectric energy harvesters to extend the operation bandwidth and enhance the efficiency of the traditional triboelectric harvesters. Our harvester design consists of a cantilever beam with a tip magnet facing another fixed magnet at the same polarity, inducing a nonlinear magnetic repulsive force. The lower surface of the tip magnet acts as an upper electrode of a triboelectric harvester, while the lower electrode with attached Polydimethylsiloxane (PDMS) insulator. Under the effect of base excitation, the system can vibrate in monostable or bistable oscillations by varying the distance between the two magnets, causing an impact on the triboelectric electrodes, and an alternative electrical signal is generated at a wide range of frequencies. The harvester's static and dynamic behaviors are investigated theoretically and experimentally validated at different separation distances between the two magnets. We achieved higher bandwidth by combining Vibro-impact with magnetic nonlinearity, and triboelectric energy harvesters show promising applications for future wireless sensor networks at wider operation frequency bandwidth.