A Master of Science thesis in Mechatronics Engineering by Maleka AbdulBari Bin Tarsh entitled, "Acoustic Energy Harvesting using Dual Piezoelectric Plates," submitted in May 2017. Thesis advisor is Dr. Jin-Hyuk Lee. Soft and hard copy available.
Sound is abundant energy found in our everyday lives, especially in urban places. Acoustic energy can be thought of as a good alternative energy source. Despite the fact that the sound is prevalent; it is challenging to scavenge energy for practical application due to the low-power density. However, the harvested energy from acoustics can be used to power low-power electronic devices. Researchers have established various techniques and mechanisms to increase the harvested energy at the low frequency range. One widely famous and effective mechanism is the use of piezoelectric (PZT) transducers. This technique has been used by many researchers to maximize the energy harvested from sound (vibration). Dual piezoelectric cantilever plates will be employed to harness the acoustic waves and obtain the natural frequency. The natural frequency is first determined through a proposed mathematical model and it is found to be 247 Hz. Then, the natural frequency is verified by a numerical method used by COMSOL Multiphysics software and it is found to be 242 Hz. This frequency is then validated with experimental data and it found to be 239 Hz; which is close to the mathematical and simulation results. The dual piezoelectric cantilever plates will be placed inside a quarter-wavelength straight-tube resonator. The tube resonator works as an amplifier when an incident wave travels through it. An acoustic resonant wave is applied and drives the PZT plates causing it to generate energy. The amplification ratio is 3.58 dB at the resonant frequency (239 Hz). Several tests are carried out to validate the resonant frequency within the tube resonator and it is verified to be 239 Hz. Furthermore, multiple tests are conducted with tube resonator placed at different locations from the acoustic source. Those tests confirmed that the maximum voltage is produced at the resonant frequency (239 Hz). The goal of this research is to find an improved way to harvest the currently wasted acoustic/vibration energy through piezoelectric cantilever plates.