Thermoacoustic sound projector: exceeding the fundamental efficiency of carbon nanotubes

Nanotechnology
Ali E AlievJohn B Blottman

Abstract

The combination of smooth, continuous sound spectra produced by a sound source having no vibrating parts, a nanoscale thickness of a flexible active layer and the feasibility of creating large, conformal projectors provoke interest in thermoacoustic phenomena. However, at low frequencies, the sound pressure level (SPL) and the sound generation efficiency of an open carbon nanotube sheet (CNTS) is low. In addition, the nanoscale thickness of fragile heating elements, their high sensitivity to the environment and the high surface temperatures practical for thermoacoustic sound generation necessitate protective encapsulation of a freestanding CNTS in inert gases. Encapsulation provides the desired increase of sound pressure towards low frequencies. However, the protective enclosure restricts heat dissipation from the resistively heated CNTS and the interior of the encapsulated device. Here, the heat dissipation issue is addressed by short pulse excitations of the CNTS. An overall increase of energy conversion efficiency by more than four orders (from 10-5 to 0.1) and the SPL of 120 dB re 20 μPa @ 1 m in air and 170 dB re 1 μPa @ 1 m in water were demonstrated. The short pulse excitation provides a stable linear increase of output ...Continue Reading

References

Aug 20, 2005·Science·Mei ZhangRay H Baughman
May 29, 2010·Nano Letters·Ali E AlievRay H Baughman
Nov 3, 2010·Nano Letters·V VesterinenP Helistö
Mar 3, 2011·ACS Nano·Albert G NasibulinEsko I Kauppinen
May 20, 2011·ACS Nano·He TianLi-Tian Liu
May 15, 2013·Nanotechnology·Ali E AlievRay H Baughman
Mar 10, 2015·ACS Nano·Ali E AlievSeon Jeong Kim
Apr 3, 2016·The Journal of the Acoustical Society of America·Troy M BoumanMahsa Asgarisabet
Nov 2, 2016·ACS Applied Materials & Interfaces·Ali E AlievJohn P Ferraris
Oct 27, 2016·Nanotechnology·J J BrownV M Bright
Dec 3, 2017·The Journal of the Acoustical Society of America·Benjamin R DzikowiczJeffrey W Baldwin

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Citations

Jul 22, 2021·Advanced Materials·Alexandre F CarvalhoFlorinda M Costa
Mar 19, 2020·ACS Nano·Yancong QiaoTian-Ling Ren

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