Background and development of a high-powered carbon nanotube thin-film loudspeaker

The thermophone, conceived in 1917 by Arnold and Crandall, was a unique sound generation device utilizing thermoacoustics, or fluctuating temperature which in turn generates a propagating sound pressure wave. Unfortunately, the thermophone had limited application at that time due to the available materials. The heat capacity of the available materials was not low enough to generate significant sound levels at audio frequencies. Recently, researchers of carbon nanotubes (CNT) have developed techniques to create a super-aligned thin-film of multi-walled CNT. This CNT thin-film possesses the extremely low heat capacity necessary to make a thermophone a reality for audio applications. This paper will introduce the CNT thin-film loudspeaker history and theory as well as some initial investigations into the feasibility of a high-powered audio CNT speaker. The advantages of such a speaker include: ultra-lightweight, no moving parts, low cost, compact size, and no dependence on rare-earth materials.