2023 ASEE Annual Conference & Exposition

Energy harvesting has been widely researched in the past decade due to its significant usage for providing energy to remote areas and electronic devices. Harvesting energy from piezoelectric beams is one of the popular forms of energy conversion, enabling a wide range of applications. A team of four senior undergraduate students in a microfabrication course completed a project to develop a piezoelectric-based acoustic energy harvester. The students performed all development steps, including ideation, literature review, calculation, design, fabrication, assembly, testing, and writing. This paper investigates the plausibility of maximizing the generation of acoustically harvested energy by combining multiple generally known methods for harvesting acoustic energy from sound waves. One such method is using a Helmholtz resonator, a spherical device with one opening, which can create a region of considerable pressure variation when sound waves are directed inside. Another method for acoustic energy harvesting is utilizing the principles of resonance and antinodes in a cylindrical tube. Antinodes are areas of high sound pressure created by standing sound waves resonating through a cylindrical tube at specific frequencies. Our design combines these methods by placing a Helmholtz resonator at the closed end of a cylindrical tube to harvest energy from all areas of high pressure due to resonance; located at the antinodes along the cylinder. The open end of the cylinder expands outward in a parabolic fashion to increase the surface area for capturing as many incident sound waves as possible and directing them into the device. The acoustic energy harvester is fabricated using a three-dimensional (3D) print of the solid model constructed of PLA, a thermoplastic polyester. The device was tested using a speaker projecting known frequencies in the range of optimal frequencies of 600-2500Hz and a data acquisition card (DAQ) measuring voltages for each 100Hz increment. It was determined that the waveform amplitude of 12.13mV produced at 2300Hz was the highest compared to the ones taken at lower frequencies. This evidence proved that the device is more effective at higher frequencies.