Tech Shout!

Scientists at the University of California, Berkeley have successfully managed to build the world’s smallest radio, which comprises a single carbon nanotube that is one-thousandth the diameter of a human hair.

This miniscule radio requires only a battery and earphones to tune in to your favorite radio station.

In what deserves to be called a milestone, these scientists successfully received their first FM broadcast in 2006 with Derek & The Dominos’ “Layla” and the Beach Boys’ “Good Vibrations” songs transmitted from across the room.

Further, in homage to last year’s 100th anniversary of the first voice and music radio transmission, the scientists also transmitted and successfully tuned in to the first music piece broadcast in 1906, which was none other that the famous music piece “Largo” by George Frederic Handel in his opera titled “Xerxes”.

The nanoradio, which is currently configured as a receiver but could also work as a transmitter, is 100 billion times smaller than the first commercial radios, and could be used in any number of applications - from cell phones to microscopic devices that sense the environment and relay information via radio signal.

According to Alex Zettl, UC Berkeley professor of physics, since it is extremely energy efficient, it would integrate well with microelectronic circuits.

The nanoradio detects radio signals in a radically new way - it vibrates thousands to millions of times per second in tune with the radio wave. This makes it a true nanoelectromechanical device, dubbed NEMS, that integrates the mechanical and electrical properties of nanoscale materials.

In a normal radio, ambient radio waves from different transmitting stations generate small currents at different frequencies in the antenna, while a tuner selects one of these frequencies to amplify. In the nanoradio, the nanotube, as the antenna, detects radio waves mechanically by vibrating at radio frequencies. The nanotube is placed in a vacuum and hooked to a battery, which covers its tip with negatively charged electrons, and the electric field of the radio wave pushes and pulls the tip thousands to millions of times per second.

Finally, the field-emission and vibration together also demodulate the signal.

“I hate to sound like I’m selling a Ginsu knife - But wait, there’s more! It also slices and dices! - but this one nanotube does everything; it performs all radio functions simultaneously and extremely efficiently,” Zettl said. “It’s ridiculously simple - that’s the beauty of it.”

Zettl won’t only be tuning in to oldies stations with his nanoradio. Because the radio static is actually the sound of atoms jumping on and off the tip of the nanotube, he hopes to use the nanoradio to sense the identity of atoms or even measure their masses, which is done today by cumbersome large mass spectrometers.