Recently, Chinese researchers developed loudspeakers as thin as paper: these are the nanotube speakers. Users can attach it to windows, walls, or clothes. Additionally, people can even insert this loudspeaker into a human ear! The devices consist of transparent carbon nanotube films. People consider them the smallest loudspeakers in the world. Because of their size and portability, they’re suitable for a wide variety of new digital electronic devices, as well as several additional applications. In this respect, the transmission of sound and music are the most popular ones.
A History of Nanotubes
Firstly, carbon nanotubes, or CNTs, are carbon tubes measured in nanometers. The most common ones are the single-wall carbon nanotubes (SWCNTs) with diameters in the range of a nanometer. In addition, there are also multi-wall carbon nanotubes (MWCNTs), which are made of nested single-wall nanotubes. Double and triple-wall carbon nanotubes are part of this same family.
Manufacturers create carbon nanotubes with fullerenes. Single-wall carbon nanotubes are one of the allotropes of carbon, intermediate between fullerene cages and flat graphene. SWCNTs are cutouts from a two-dimensional hexagonal lattice of carbon atoms. They roll up along one of the Bravais lattice vectors of the hexagonal lattice and form a hollow cylinder. When carbon nanotubes emerge, periodic boundary conditions press over the length of this roll-up vector. They do so to yield a lattice with helical symmetry of seamlessly bonded carbon atoms on the cylinder surface.
Nanotube Speakers and the Thermoacoustic Effect
Because of a thermoacoustic effect, the films included in carbon nanotube speakers can produce sound by applying an audio frequency current. The ultra-small heat capacity per unit area of CNT thin films can lead to a wide frequency response range. It can lead, too, as a high sound pressure level. To create a loudspeaker, experts took a super aligned CNT arrangement grown on a 4-inch silicon wafer and put on two electrodes of a frame.
Too high-tech?
Nanotube speakers, just as transparent ionic conduction and plasma arc ones, are very high tech. If you’re looking for something more conventional, try learning from digital, electrodynamic, full-range, mid-range, woofer, subwoofer, tweeter, and coaxial speakers. You can also consult piezoelectric, magnetostatic, and magnetostrictive, and planar magnetic ones. You can, too, delve into flat-panel loudspeakers, such as ribbon and electrostatic.
