A High-Performance Coniform Helmholtz Resonator-Based Triboelectric Nanogenerator for Acoustic Energy Harvesting

Harvesting acoustic energy in the environment and converting it into electricity can provide essential ideas for self-powering the widely distributed sensor devices in the age of the Internet of Things. In this study, we propose a low-cost, easily fabricated and high-performance coniform Helmholtz resonator-based Triboelectric Nanogenerator (CHR-TENG) with the purpose of acoustic energy harvesting. Output performances of the CHR-TENG with varied geometrical sizes were systematically investigated under different acoustic energy conditions. Remarkably, the CHR-TENG could achieve a 58.2% higher power density per unit of sound pressure of acoustic energy harvesting compared with the ever-reported best result. In addition, the reported CHR-TENG was demonstrated by charging a 1000 μF capacitor up to 3 V in 165 s, powering a sensor for continuous temperature and humidity monitoring and lighting up as many as five 0.5 W commercial LED bulbs for acoustic energy harvesting. With a collection features of high output performance, lightweight, wide frequency response band and environmental friendliness, the cleverly designed CHR-TENG represents a practicable acoustic energy harvesting approach for powering sensor devices in the age of the Internet of Things.

The Potential of Cylindrical Piezoelectric Transducers for High-Frequency Acoustic Energy Harvesting

The work presented in this paper studies the potential of cylindrical piezoelectric transducers for harvesting high-frequency acoustic energy. The cylinder was made of a modified PZT (lead zirconate titanate) and had the shape of a squared cylinder with a side length of 4 cm and a wall thickness of 1 mm. The study used open-circuit measurements to study the relationship between the sound wavelength and the cylinder size and its effect on the performance of energy harvesting. The cylinder was found to give the best performance at a frequency of 20 kHz. In addition to open-circuit measurements, closed-circuit measurements were performed to demonstrate the ability to dissipate energy harvested from 20 kHz sound waves across an electric load. The load was designed in a series of experimental steps that aimed at optimizing an impedance-matched energy harvester. Finally, the cylinder was tested at the optimized load conditions, and it was possible to harvest and store energy with a power of 67.6 μW and harvesting efficiency of 86.1%.

Recent acoustic energy harvesting methods and mechanisms: A review

This review article summarises the mechanism of the acoustic energy harvester or converter which includes the compact structure of the piezoelectric element, electromagnetic transducer and Helmholtz resonator; different shapes of Helmholtz resonators, piezoelectric cantilever, acoustic metamaterial-based approach, electrostatic transduction method, auxetic structure of material and other techniques. The recently established methods of acoustic energy harvesting and converting mechanisms; devices are carefully reviewed, and their results are compared and listed in the table. The technique of energy conversion by using acoustic metamaterial will tend to be more efficacious due to its complexity and the structure. Even in the few noise attenuation applications, more metamaterial is used, where, with the help of the conversion mechanism, the noise or sound energy can be converted into electrical energy for small electronic applications. It is demonstrated that the acoustic energy-conversion technique will become an essential part of the environmental energy harvesting research field.

An Optimal Piezoelectric Beam for Acoustic Energy Harvesting

This study presents a novel piezoelectric beam structure for acoustic energy harvesting. The beams have been designed to maximize output energy in areas where the noise level is loud such as highway traffic. The beam consists of two layers (copper and polyvinylidene fluoride) that convert the ambient noise’s vibration energy to electrical energy. The piezoelectric material’s optimum placement have been studied, and its best positon is obtained on the substrate for the maximum yield. Unlike previous studies, which the entire beam substrate used to be covered by a material, this study presents a modest material usage and contributes to lowering the harvester’s final production cost. Additionally, in this study, an electrical model was developed for the sensor and a read-out circuitry was proposed for the converter. Moreover, the sensor was validated at different noise levels at various lengths and locations. The simulations were performed in COMSOL Multiphysics® and MATLAB® and report a maximum sound pressure of 140 dB from 100 dB point sources in an enclosed air-filled cubic meter chamber.