A mosquito-inspired self-adaptive energy harvester for multi-directional vibrations

In this paper, a new concept of direction self-adaptive energy harvesting is put forward for multi-directional vibrations, and a novel direction self-adaptive piezoelectric energy harvester (DSPEH) is explored by introducing a self-adaptive rotation mechanism into the cantilever beam inspired by mosquito wings to validate the new concept. Different from the conventional piezoelectric energy harvester (PEH), the proposed DSPEH has an additional rotation degree of freedom obtained by the rotation unit to realize self-adaptive rotation passively without any manual intervention or power supply. Working principle and theoretical analysis of the proposed DSPEH are conducted and a prototype is fabricated to demonstrate the concept. The energy harvesting performance of the proposed DSPEH is investigated under sweeping frequency and harmonic excitation, and the key parameters affecting the energy harvesting efficiency, such as damping parameters and mass eccentricity coefficient, are analyzed in detail. Simulation and experimental results are in good agreement. Owning to the characteristic of self-adaptive rotation, the most attractive feature of the proposed DSPEH is not simply the ability to realize multi-directional vibration energy harvesting, but the capability of achieving stable and high voltage output levels in multi directions, which is fundamentally distinct from the conventional PEH and other multi-directional energy harvesters. The average output voltage is 30% higher than that of the conventional PEH. Compared with other multi-directional energy harvesters, the proposed DSPEH also has higher energy harvesting efficiency.