A Carbon-Based Thermoacoustic Speaker With High Vocal Efficiency and Low Power Consumption

Abstract

Improving vocal efficiency and reducing power consumption are indispensable conditions to promote the wider applications of thermoacoustic devices. In this work, three kinds of thermoacoustic speakers based on different carbon-based materials are investigated. An analytical thermoacoustic model is proposed. This analytical thermoacoustic model considers the effect of phase on the sound pressure (SP) amplitude to improve the accuracy. In addition, this analytical thermoacoustic model considers the input power distribution, has good convergence, and simplifies the calculation. Sample fabrication and material characterization of three thermoacoustic speakers are given. The measured vocal efficiencies are <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.52\times 10^{-{7}}$ </tex-math></inline-formula> %, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.32\times 10^{-{7}}$ </tex-math></inline-formula> %, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.22\times 10^{-{7}}$ </tex-math></inline-formula> % for reduced graphene oxide (RGO), multiwalled carbon nanotube (MWCNT), and laser scribed graphene (LSG) samples, respectively, whose corresponding highest SP levels (SPLs) are 65.24, 57.41, and 40.68 dB. The measured results show that the fabricated RGO speaker has lower power consumption and higher effective vocal efficiency than the other two loudspeakers due to its high crystal quality and additional heat exchanger nanofins. This will provide its potential application in the field of wearable electronic devices.