Multi-purpose triboelectric-electromagnetic hybrid nanogenerator with a mechanical motion-controlled switch for harvesting low-frequency energy

Abstract

The renewable mechanical energy is pervasive but mainly contained in diverse, low-frequency and irregular motions, making its efficient exploitation highly difficult. Here, a multi-purpose triboelectric-electromagnetic hybrid nanogenerator (M-TEHG) is developed to tackle this issue through an ingenious mechanical motion-controlled switch (MMS). Consisting of a sprung-pendulum, a stiffness-adaptive plectrum and a slideable rotor, the MMS can not only transform low-frequency motions to one-way and high-speed spin but also enable the M-TEHG to automatically switch between non-contact state and contact state under the action of the rotor gravity. The M-TEHG exhibits frequency-multiplied outputs, improved durability, and superior adaptability to various motions. When triggered by low-frequency (≤ 5 Hz) swings and vibrations, the watch-sized M-TEHG can provide milliwatt-level electric power. When the M-TEHG is exposed to irregular water waves of around 1 Hz, the output power can reach roughly 0.7 mW. By harvesting human arm motions and water waves, the M-TEHG can power an electronic watch, drive a hygrometer, and light up 120 LEDs. This work provides a prospective strategy for tapping diverse low-frequency irregular motions as a green power source for wearable electronics and environment sensing systems.