[OKDXA] Yeah, But Does It Shoot Skip On The CB?

[AC5UP]

Cal physicists make a radio 10,000 times thinner than a human hair
Bernadette Tansey, Chronicle Staff Writer
Thursday, November 1, 2007

Physicists at UC Berkeley say they have produced the world's smallest 
radio out of a single carbon nanotube that is 10,000 times thinner than 
a human hair.

Professor Alex Zettl led a team that developed the minuscule filament, 
which can be tuned to receive AM or FM transmissions.

The first song it played? "Layla" by Derek & the Dominos. Eric Clapton's 
unmistakable guitar riff can be heard on a scratchy recording of the 
nanoradio's output posted by Zettl online.

Zettl said the device, built by graduate student Kenneth Jensen, is the 
first radio within the size range of nanotechnology, which covers 
inventions no larger than 100 billionths of a meter. The nanoradio is 
100 billion times smaller than the first commercial radios of the early 
20th century. It is a thousand times smaller than the most minute radios 
in use today, which are based on silicon chip technology.

The research team has no commercial partners yet, but Zettl said the 
practical applications of the nanoradio could include cell phones, 
climate-monitoring systems and radio-controlled diagnostic probes that 
could move through the human bloodstream.

"Maybe the kids will be wearing these instead of iPods, inside their 
ears," Zettl said.

As long as 10 years ago, scientists had managed to build individual 
components of a radio on the nanoscale, he said. But Zettl and his 
colleagues figured out how to make a single nanotube perform all the 
functions of a radio: It serves as an antenna, tuner, amplifier and 
demodulator. The demodulator eliminates any frequencies from a radio 
transmission except the signal to be played, such as a song.

"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," Zettl said.

The key to this feat was making the nanoradio work differently from 
conventional radio electronics. The first step in that old technology is 
to convert radio waves into pulses of electronic current. By contrast, 
the nanotube absorbs the radio transmission and physically vibrates in 
response, like a tuning fork or the tiny hairlike structures inside the 
human ear. The filament has one end mounted in an electrode, but the 
other end is free. Its vibrations change the patterns in an electric 
field created by a battery. The varying electronic patterns become 
sounds or music audible through headphones.

Jensen's choice for one of the first songs played on the nanoradio was 
"Good Vibrations" by the Beach Boys.

But there is indeed more. The nanotube can also function as a 
transmitter. Theoretically, thousands of nanoradios distributed through 
the air or in the bloodstream could send back signals about air quality 
or the state of a patient's cells, Zettl said.

Carbon nanotubes are immensely strong compounds made of carbon atoms 
linked in a structure that looks like chicken wire. The carbon sheets 
can be formed into hollow tubes. Zettl's research team tweaked the 
nanotube structures and found that multi-walled cylinders - tubes within 
tubes - were better for picking up AM and FM transmissions. 
Single-walled nanotubes were best for receiving the frequencies used in 
cell phones.

The team built a transmitter in the lab based on conventional 
electronics, and first proved that the nanoradio could pick up and play 
"Layla" about 10 months ago. But the scientists held the news for 
publication in the journal Nano Letters, which posted it online on 
Wednesday. Along with Jensen and Zettl, the co-authors of the paper were 
UC Berkeley postdoctoral fellow Jeff Weldon and physics graduate student 
Henry Garcia. The project was funded by the National Science Foundation 
and the Department of Energy.

This article appeared on page C - 1 of the San Francisco Chronicle

http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2007/11/01/BUTBT44A2.DTL&type=business