The abstract of their paper states, “We have constructed a fully functional, fully integrated radio receiver from a single carbon nanotube. The nanotube serves simultaneously as all essential components of a radio: antenna, tunable band-pass filter, amplifier, and demodulator. A direct current voltage source, as supplied by a battery, powers the radio. Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation techniques, we demonstrate successful music and voice reception.”
The single carbon nanotube, which makes up the nanoradio, consists of rolled-up single-walled sheets of interlocked carbon (graphene) atoms with highly specific electronic properties due to its nanometer dimensions.
One nanotube is about 10 nanometers in diameter, where one nanometer is equal to one-billionth of one meter. The length of one nanotube within the nanoradio is about 700 nanometers. When rolled up the carbon atoms form a very strong tube.
In the case of their nanoradio, only one nanotube is used for the antenna, tuner, amplifier, and demodulator (for both AM [amplitude modulation] and FM [frequency modulation] radio stations), all the parts of a traditional radio.
They only need a battery and earphones to listen to it. In fact, some of the first sounds that came out of their nanoradio were the songs “Layla” by Derek and The Dominos and “Good Vibrations” by the Beach Boys.
The nanoradio, which is considered a nanoelectromechanical device (NEMS), is placed in a vacuum and hooked up to a battery. The battery side of the nanoradio contains negatively charged electrons. The tip contained on this side of the nanoradio is vibrated thousands to millions of times per second in unison with a radio wave in order to detect the radio signal.
On the other end (the free end), a large object vibrates only tens to hundreds of times per second.
The physicists then can vary the tension in the nanotube to select different radio stations by pulling on the free end with a positively charged electrode. The electrode also works as an amplifier, increasing the sound of the incoming radio waves.
The scientists, led by University of California—Berkeley physics professor Alex Zettl, state that the technology developed from the nanoradio could be applied to any type of microelectronic-circuit devices such as those found in cell phones, Earth-orbiting satellites, and tiny radio-controlled medical devices inserted into the human body.
In fact, from the UC-Berkeley News website (“Single nanotube makes world's smallest radio”), the technology is so simple that Zettl comments, “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. It's ridiculously simple - that's the beauty of it."
The result from this nanoradio appears in the October 31, 2007 online issue of Nano Letters, under the title “Nanotube Radio,” and the regular November 6, 2007 issue of the journal Nano Letters. The authors of this paper include Zettl, Kenneth Jensen, Jeff Weldon, and Henry Garcia.