Hybridized generator: Freely movable ferromagnetic nanoparticle-embedded balls for a self-powered tilt and direction sensor

Hybrid electricity-generation technologies using two energy harvesting mechanisms have been gaining attention owing to the higher electrical output and more effective efficiency from hybridized device compared to that from the sum of individual devices. Accordingly, the synergetic effect to improve electrical output performance is a crucial key for our real-life applications. For the reason, the hybridization of a triboelectric nanogenerator (TENG) and electromagnetic nanogenerator (EMG) is conducted to explore high and stable output from one mechanical input vibration. With the aim of effective energy harvesting in the low level of mechanical vibration, a freely movable thermoplastic polyurethane (TPU) ball could be acted as the dielectric material in freestanding mode of TENG. In this work, a proposed hybridized generator, ferromagnetic-embedded TENG (FME-TENG) that combines a TENG and an EMG that can be operated with FME-balls. Herein, FME-balls were fabricated with the aid of 3D printing technology. Also, a facile precipitation method is used to synthesize the Fe₂O₃ nanoparticles showing ferromagnetism. Therefore, a multifunctional FME-ball, as both a dielectric layer for the TENG and a magnetic flux generator for the EMG, is successfully fabricated. As a result, the electrical output power of the hybridized generator (2.25μW) was enhanced compared to the individual TENG (1.125μW) and EMG (1.85μW). Additionally, the directional dependency of the electrical output encourages the applicability of tilt and direction sensors in detecting vibration angles effectively.