When I was a young kid, I got a transistor radio as a gift and it was the greatest thing I could imagine - music coming from a box I could hold in my hand! Zettl said. When we first played our nanoradio, I was just as excited as I was when I first turned on that transistor radio as a kid.
The carbon nanotube radio consists of an individual carbon nanotube mounted to an electrode in close proximity to a counter-electrode, with a DC voltage source, such as from a battery or a solar cell array, connected to the electrodes for power. The applied DC bias creates a negative electrical charge on the tip of the nanotube, sensitizing it to oscillating electric fields. Both the electrodes and nanotube are contained in vacuum, in a geometrical configuration similar to that of a conventional vacuum tube.
Kenneth Jensen, a graduate student in Zettls research group, did the actual design and construction of the radio.
We started out by making an exceptionally sensitive force sensor, Jensen said. Nanotubes are like tiny cat whiskers. Small forces, on the order of attonewtons, cause them to deflect a significant amount. By detecting this deflection, you can infer what force was acting on the nanotube. This incredible sensitivity becomes even greater at the nanotubes flexural resonance frequency, which falls within the frequencies of radio broadcasts, cell phones and GPS broadcasting. Because of this high resonance frequency, Alex (Zettl) suggested that nanotubes could be used to make a radio.
Although it has the same essential components, the nanotube radio does not work like a conventional
|Contact: Lynn Yarris|
DOE/Lawrence Berkeley National Laboratory