A snap-through vibration-rotation modulation mechanism for high-performance low frequency energy harvester

Ambient low frequency (LF) vibrations are ubiquitous but their efficient utilization is still an open issue. To tackle this problem, this paper reports an ingenious vibration–rotation (V-R) modulation mechanism that is realized by introducing a reset spring and a pair of magnets to the conventional rack-and-pinion mechanism. By taking advantage of the magnets-enabled snap-through dynamics, the V-R mechanism can convert LF-vibrations to fast rotation. Under a pressed depth of 10 mm and trigger frequency of 2.0 Hz, a high rotation speed of 1230 rpm can be achieved by the snap-through V-R mechanism in combination with a pawl-ratchet mechanism, which is 1.4 times higher than that enabled by the linear counterpart. A rotor-based vibration energy harvester (R-VEH) designed with the snap-through V-R mechanism can generate high voltage of 4.3 V and large power of 10.8 mW as excited at 2.5 Hz. The snap-through R-VEH can also sustain the continuous work of a hygrothermograph by tapping the irregular LF-vibration of a treadmill (even with a small amplitude of roughly 2.5 mm). The snap-through R-VEH is thus a potential technology for the efficient harvesting of pervasive LF-vibrations toward self-driven sensing systems.