A finger-snapping inspired bistable mechanism for converting low-frequency vibrations to high-speed rotation

Low-frequency vibrations can be exploited to drive a series of rotation-based devices (e.g. miniaturized centrifuges and energy harvesters), but their practical applications are hindered by the low rotation speeds of vibration-to-rotation conversion mechanisms. To address this issue, we report herein a finger-snapping inspired bistable mechanism that can achieve high-speed rotation out of low-frequency vibrations (<5 Hz). The proposed bistable mechanism consists of two sprung-cranks, a proof mass attached with a curved beam, and a pawl, in which the bistability is owed to the coupling of the potential energy of the springs with that of the deformed beam. Both theoretical simulations and experimental tests have been done to show the feasibility of the bistable mechanism. When triggered by vibrations with frequencies varying from 3.2 Hz to 4.5 Hz, the bistable mechanism can drive a rotor to rotate uni-directionally with high speeds ranging from 900 rpm to 1300 rpm. At a low vibration frequency of 3.2 Hz, around 290% increase in the rotation speed can be achieved by the bistable mechanism as compared with the corresponding linear mechanism (rack-and-pinion mechanism). The finger-snapping inspired bistable mechanism is thus a promising candidate in the tapping of ambient low-frequency vibrations as a green energy source for some mechatronic devices.