A pneumatic piezoelectric vibration energy harvester based on the compressed air-transducer-structure interaction

Harvesting energy from the ambient vibration to replace the conventional electrochemical batteries has gained considerable interest. Different from the most existing flow-induced vibration energy harvesters based on the continuous airflow, by using the pressure energy of the air rather than the kinetic energy, a novel pneumatic piezoelectric vibration energy harvester (PVEH) based on compressed air-transducer-structure interaction is presented and fabricated in this paper. To verify the feasibility of the proposed principle and design, the experiments of frequency responses were performed to evaluate the energy harvesting performance in terms of vibrational displacement and open-circuit voltage. It was found that the power generation characteristics of the pneumatic PVEH was almost totally independent of the vibration properties because of the mutual interaction between the compressed air, piezoelectric transducer and damping orifice. Experimental results demonstrated there was an optimal proof mass of 12.5 kg to maximize the open-circuit voltage for this prototype PVEH. The optimal excitation frequency of the voltage-frequency response decreased linearly with the rising air pressure. With the enhancement of the initial air pressure from 0.1 MPa to 0.95 MPa, the optimal frequency was dropped from 55 Hz to 31 Hz. The open-circuit voltage could be improved through reducing the size of damping orifice, where the output voltage reached the maximum value of 51.6 V at the air pressure of 0.5 MPa with the valve opening of 1/6. Besides, more than one peak voltage would occur with the increase of the air pressure or the size of the damping orifice. It is expected that this study can provide a guideline for the design and application of the PVEH using the compressed air.