Frequency tunable, flexible and low cost piezoelectric micro-generator for energy harvesting

Abstract The conversion of vibrations into electrical energy for powering low-power small electronic components has been investigated by researchers from different disciplines in the last decade. Among the possible mechanisms, piezoelectricity has received particular attention. In the field of low frequency cantilever-based vibration energy harvesters, the proof mass is essential in order to reduce the resonance frequency and increase the stress along the beam to increase the output power. In this work, a manufacturing process of a micro generator is proposed to easily modify and increase the dimensions of the cantilever, and thus tune its resonance frequency. The effect of the position of the mass on the performances of this flexible piezoelectric energy harvester is also studied. For a proof mass at 8 cm from clamping, we obtain a resonance frequency of 9.9 Hz, a maximum power of 127 μW against a resonance frequency of 16 Hz and a maximum power of 72 μW with a mass at 4 cm. This shows that the maximum power extracted varies in ≅ 1 / f R for a constant acceleration of 1 g (9.81 m/s2), as expected theoretically. These promising results show that the prototype can be considered for a low power application as an energy harvesting-based micro-generator.