Acoustic energy harvesting using 3-D-printed acoustic metamaterials

In this work, acoustic energy harvesting using 3-D-printed acoustic metamaterials of sonic crystals is investigated. Of particular interest is to leverage acoustic energy harvesting from urban ambient noise in the mid-range frequencies, spanning from 100 to 500 Hz. This frequency band aligns well with common environmental and urban noise frequencies, ensuring a consistent and reliable energy source, thus converting it into electrical energy through the piezoelectric effect, where certain materials generate an electric charge in response to mechanical stress or vibrations. Numerical models were developed to study the transmission loss characteristics of the acoustic metamaterials to aid in the design of the acoustic metamaterials. The numerical models are designed with the intent to aid in the positioning of a piezoelectric device on the elastic resonant energy region of the acoustic metamaterial. Impedance tube experiments are performed to investigate the output power of 3-D-printed polylactic acid (PLA), thermoplastic polyurethane (TPU), and polyethylene terephthalate glycol (PETG) acoustic metamaterials. In order to optimize the output power, an assessment was conducted by systematically altering the load resistance within the range of 0–1000 MΩ.