World's Smallest Radio

This month's Scientific American has a neat article on the recent nano-development out of Berkley. The materials scientists Zettl, et al successfully demonstrated that a single carbon nanotube could perform all the functions of a conventional radio: tuning, receiving a signal, discriminating between signal and carrier wave, and amplification of the signal.

Zettl acknowledges that the ability of a single nanotube to perform as a fully-integrated radio is quite serendipitous, even going so far as to describe work on this project as an example of Murphy's Law in reverse; where everything that can go wrong, magically does not. The article in the link at the top gives a nice overview of how the device works and what novel applications could emerge as a result of this work.

What was the first broadcast received by nanotube radio? The answer to that future barroom trivia question is Eric Clapton's Layla. In the video below, once the nanotube is tuned to the signal's frequency, it becomes an indistinguishable blur. Because of the physical "weirdness" at the nanoscale, the EM wave is sufficient to mechanically vibrate the tube. These vibrations causes a change in the current through the nanotube and causes an avalanche of electrons to be emitted from the tube's end, thereby amplifying the signal. This is the so-called Field Emission current. This current is then passed on to an audio loudspeaker and turned into an audible sound wave.