CARBON-nanotube speakers may help to reveal the secrets of the deep seas. Engineers have created an underwater speaker using thin sheets of nanotubes, which they hope could provide a lightweight alternative to the sound projectors used in long-range sonar.
The team knew that passing an alternating current through carbon-nanotube sheets could mimic the vibrations of a speaker cone, as the sheet quickly heats and cools the surrounding air.
Now Ali Aliev‘s team at the NanoTech Institute, University of Texas at Dallas, has shown that the speakers work surprisingly well underwater. Water’s high heat capacity and low thermal expansion would normally absorb any temperature fluctuations. But…
