Researchers have fashioned the world's tiniest radio out of a carbon nanotube:

The nanotube radio works differently than a conventional radio does. Conventional radios have four main functional parts: antenna, tuner, amplifier, and demodulator. Radio waves falling on a radio antenna create electric currents at different frequencies. When someone selects a radio station, the tuner filters out all but one of the frequencies. Transistors amplify the signal, while a demodulator, typically a rectifier or a diode, separates the data--the music or other audio--that has been encoded on a "carrier" electromagnetic wave.

Zettl's team used one carbon nanotube for all these functions. Because of their unique electrical properties, carbon nanotubes have been previously used to make electronic components such as diodes, transistors, and rectifiers. "It was a revelation that all of this could be built into the same [nanotube]," Zettl says.