A highly miniaturized freestanding kinetic-impact-based non-resonant hybridized electromagnetic-triboelectric nanogenerator for human induced vibrations harvesting

This paper presents a highly miniaturized freestanding kinetic-impact-based hybridized nanogenerator (MFKI-HNG) to effectively harvest human-induced vibrations. It integrates an electromagnetic generator (EMG) and a freestanding-mode triboelectric nanogenerator (TENG) to generate hybridized outputs from the same mechanical load. A non-resonant mechanical system improves performance in the low-frequency range (≤5 Hz).

• Design of a highly miniaturized, freestanding, kinetic-impact-based hybridized nanogenerator (MFKI-HNG).
• Integration of EMG and TENG for simultaneous energy harvesting from low-frequency vibrations.
• Use of a non-resonant mechanical system to improve low-frequency performance.
• Demonstrated ability to power multiple commercial LEDs and act as a portable power source for smartphones and smartwatches.

The MFKI-HNG was designed with a non-resonant system and enhanced tribo-materials (nanowire and micro-nano hierarchical structures). Its performance was optimized using theoretical modeling and simulations and then tested with both a shaker and human motions. A custom power management circuit was used for practical applications.

The MFKI-HNG generated a maximum output power of 102.29 mW, with a normalized power density of 3.67 mW cm⁻³ g⁻². It successfully powered 380 commercial LEDs, thermo-hygrometers, and charged modern electronics like smartphones. A wireless temperature sensor ran for over 70s from just 6s of excitation.