A flute-inspired broadband piezoelectric vibration energy harvesting device with mechanical intelligent design

Currently, the practicability of vibration energy harvesting devices is restricted by narrow resonant bandwidths. To realize broadband, high-efficiency vibration energy harvesting, here we propose a flute-inspired mechanical-intelligent piezoelectric energy harvester to achieve self-tracking vibration frequency without manual interventions. This harvester adjusts its natural frequency in a way reminiscent of how the tone of a flute is altered (i.e., by moving a sliding mass on the longitudinal arranged hole of a cantilever beam). The mechanical intelligence is reflected in self-tuning and self-locking following its dynamic responses. The natural frequency of the proposed device approaches the external excitation frequency by self-tuning, and the resonant state is stably maintained by self-locking. Comparison experiments with its linear counterpart, this flute-inspired mechanical-intelligent vibration energy harvester demonstrates a significant improvement of 610% in working bandwidth and an increase in power of 348%. Compared with the tunable beam-slider structure without mechanical-intelligence, the proposed energy harvester shows 235% increasing in operating bandwidth and 659% increasing in working efficiency. Practical applications of powering an electronic clock and charging a capacitor show the feasibility of this energy harvester used for the engineering community. This study provides a mechanical-intelligent design approach for piezoelectric vibration energy harvester, which may also be applied to other vibration energy harvesters using electromagnetic, triboelectric or hybrid transductions.