Abstract
Harvesting multi-frequency sound energy from environmental noise is a meaningful topic to supply energy for potential devices. In this work, we constructed an array of Helmholtz resonators (HRs) with cross-linked polypropylene (IXPP) ferroelectret films on the inner walls of HR cavities, whose resonant frequencies range from 300 to 800 Hz and quasi-static piezoelectric coefficient d33 is 230 pC/N. The energy harvesting performance of IXPP films is investigated, both theoretically and experimentally, in a single HR with various sizes, showing the high energy conversion capability close to the resonant frequencies of HRs, e.g., 337, 375, 445, 522, 588, 661, 739, 782, and 795 Hz, in the experiment. By putting one, two, three, and four samples of nine different sized HRs in series connection in order, we measured the average output power of 3.16, 5.31, 7.36, and 8.66 nW at the resonant frequencies. It shows that the output power of IXPP films has been significantly improved at multiple frequencies by series connection of IXPP films. In parallel, the optimal electrical resistance increases in a quasilinear way compared to the number of HRs. These results are helpful for designing efficient sound energy harvesters in the broadband frequency range.
Highlights
During the past few decades, gathering renewable energy from the environment,1 such as solar,2 vibration,3,4 wind,5,6 heat,7 and acoustic energy,8–14 has attracted increasing attention
When increasing the series number of the acoustic energy harvester, it can be seen that both the maximum output power and the optimal load resistance increase almost linearly when a number of samples are put in series connection for each Helmholtz resonators (HRs), which provides a useful way for improving the sound energy harvesting performance
We have realized sound energy harvesting at multiple frequencies by using nine different sized HRs with IXPP films in the range of 300–800 Hz, which can be used in road transport and high-speed railways
Summary
During the past few decades, gathering renewable energy from the environment, such as solar, vibration, wind, heat, and acoustic energy, has attracted increasing attention. Environmental noise occurs in the form of sound with small energy density and distributes in the broadband low frequency range. It is a challenge to harvest sound energy efficiently.18–23 In this line, Ma et al had attempted to transform sound energy to electrical power, and the acoustic power conversion efficiency achieved by them is 23% based on electromagnetic induction.. Helmholtz resonators (HRs) and ferroelectric PVDF to convert sound energy into electricity. They realized acoustic-electrical conversion at a resonant frequency of 468 Hz under a sound pressure level (SPL) of 110 dB.. Zhang et al had combined HRs and PVDF and had gotten output power within 90 Hz wide frequency ranges.. They realized acoustic-electrical conversion at a resonant frequency of 468 Hz under a sound pressure level (SPL) of 110 dB. Zhang et al had combined HRs and PVDF and had gotten output power within 90 Hz wide frequency ranges. Yuan et al had bonded a piezoelectric patch in a helix structure to harvest power at a resonant frequency of 175 Hz.
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