A Radio 10,000 Times Thinner Than A Human Hair

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. More: http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2007/11/01/BUTBT44A2.DTL&%20type=business Printable: http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2007/11/01/BUTBT44A2.DTL&type=printable

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