A cantilever-driven rotor for efficient vibration energy harvesting

The pervasive renewable vibration energy has been considered as a promising alternative to electrochemical energy of batteries for powering wireless sensors and wearable electronics, but its efficient harvesting is still an unsolved problem. To tackle this issue, this paper presents an innovative mechanical modulation mechanism, which we name ‘cantilever-driven rotor’, to convert vibrations to uni-directional rotation aiming to achieve improved energy harvesting performance. Compared with the conventional cantilever-based energy harvesters (CBEHs), the rotor-based energy harvester (RBEH) can provide both enhanced output power (1.8 mW versus 0.3 mW) and extended working bandwidth (4.5 Hz versus 1.9 Hz) under a harmonic vibration of 0.8 g (1 g = 9.8 m/s²). Moreover, electric outputs of the RBEH can persist for 27 s after the external excitation vanishes. With the electric energy generated by the RBEH from the harmonic vibration, a wireless acceleration sensor could be powered to perform with its full functionality. When attached to the human ankle, the RBEH can maintain the normal operation of a Timer under a walking speed of 6 km/h. This work provides a basically different vibration-to-rotation conversion mechanism with superior performance in vibration energy exploitation and potential applications in self-sustained wireless sensors and wearable electronics.