No abstract

A flexible and elastic carbon coil (see figure) has been fabricated using a continuous yarn of carbon nanotube arrays. The processed yarn is both elastic and pliable and can be freely manipulated and molded to any desired shape that is retained after heat treatment. Owing to their highly ordered macroscopic structures, the good electrical and thermal conductivity of the nanotube components, and their good mechanical properties, these carbon nanostructures may find extensive use in a wide range of applications.

We found that very thin carbon nanotube films, once fed by sound frequency electric currents, could emit loud sounds. This phenomenon could be attributed to a thermoacoustic effect. The ultra small heat capacity per unit area of carbon nanotube thin films leads to a wide frequency response range and a high sound pressure level. On the basis of this finding, we made practical carbon nanotube thin film loudspeakers, which possess the merits of nanometer thickness and are transparent, flexible, stretchable, and magnet-free. Such a single-element thin film loudspeaker can be tailored into any shape and size, freestanding or on any insulating surfaces, which could open up new applications of and approaches to manufacturing loudspeakers and other acoustic devices.