Noise-less hybrid nanogenerator based on flexible WPU and siloxene composite for self-powered portable and wearable electronics

The rapid growth of portable and wearable electronics demands innovative battery solutions that are both sustainable and eco-friendly. Biomechanical energy-harvesting technology is a promising approach for operating wearable electronic devices without battery dependence. In this study, a novel noise-less hybrid nanogenerator (NLHN) was developed using 3D-printed elastic resin springs and burr-shaped water-based polyurethane (water -based PU: WPU)@Siloxene nanocomposite to effectively harvest low-frequency biomechanical energy from various human movements without generating any physical noise. By rationally integrating electromagnetic generators with triboelectric nanogenerators in a sliding mode and two contact modes, the proposed NLHN exhibited excellent output performance under random low-frequency and wide-range vibrational excitations. The WPU@Siloxene was first introduced as a highly flexible positive triboelectric layer and a noise suppressor during the sliding mode operation, while elastic resin springs significantly improved the energy harvesting performance thereby suppressing the physical noise during contact-separation. The NLHN exhibited an optimal output power of 101 mW at 6 Hz and 1.5 g acceleration. Moreover, the NLHN suppressed operating noise to only 41 dB during operation and maintained a stable output performance after 50,000 cycles. The NLHN was demonstrated to function as a continuous power source for powering portable and wearable electronics, such as smart bracelets and smartphones as well as battery-free wearable ECG monitoring systems. Conclusively, the proposed NLHN has substantial potential for silent biomechanical energy harvesting as a sustainable and eco-friendly power source for portable electronics and wearable healthcare sensing devices.