Nanoradio gives new meaning to ‘small’

The world of incredible shrinking technology has created a radio 100 billion times smaller than the first commercial radios.

University of California, Berkeley, researchers have listened to tunes on a “nanoradio” one ten-thousandth the diameter of a human hair.

The scientists heard their first FM broadcast last year — Derek & The Dominos’ “Layla” and the Beach Boys’ “Good Vibrations” — transmitted from across a room.

“We were just in ecstasy when this worked,” team leader Alex Zettl said in a release from UC Berkeley. “It was fantastic,” the physics professor said.

It could be used in any number of applications — from cell phones to microscopic devices that sense the environment and relay information via radio signals, Zettl said.

It also could lead to radio-controlled devices small enough to exist in a human’s bloodstream.

The nanotube might even be a step toward a Star Trek-like matter analyzer: Because it can identify atoms, Zettl said he hopes it can do what is done today by cumbersome large mass spectrometers.

Zettl and graduate student Kenneth Jensen will reveal their tiniest-ever radio in the Nov. 6 issue of the journal Nano Letters. Post-doctoral fellow Jeff Weldon and physics graduate student Henry Garcia were co-authors.

Nanotubes are rolled-up sheets of interlocked carbon atoms that exhibit unusual electronic properties.

In the nanoradio, a single nanotube works as an all-in-one antenna, tuner, amplifier and demodulator for both AM and FM.

Demodulation is the separation of AM and FM signals.

In a regular radio, an antenna captures radio waves from different stations. The nanoradio detects radio signals as it vibrates thousands to millions of times per second in tune with a radio wave.

Regular radios have a tuner that selects one frequency or station to amplify.

The researchers tune their nanoradio by using an electrode to “pull” one end of the tube to change its tension. This influences its natural vibration frequency just as the tension on a guitar string fine tunes its pitch.

The electrode also turns the nanotube into an amplifier and the amplified output is enough to drive a very sensitive earphone.

“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.”