[Antennas] Tiny Nanotube Antennas May Yield Better Signals In Cell Phones, Televisions

[Ed Tanton]

From: Science Daily 
<http://www.sciencedaily.com/releases/2003/12/031231082951.htm>

In the future, your cell phone calls and television pictures could become a 
lot clearer thanks to tiny antennas thousands of times smaller than the 
width of a human hair. At least that's the speculation of a University of 
Southern California researcher who has been investigating nanotube transistors.

The USC scientist, Bart Kosko, Ph.D., a professor in the school's 
Electrical Engineering Department, led a study that has demonstrated for 
the first time that minuscule antennas, in the form of carbon nanotube 
transistors, can dramatically enhance the processing of electrical signals, 
a development that could pave the way for improved performance of consumer 
electronic devices.

The finding adds to a growing number of promising electronic components 
that are nanotube-based, including logic gates for computers and diodes for 
light displays. The study appears in the December issue of Nano Letters, a 
monthly peer-reviewed publication of the American Chemical Society, the 
world's largest scientific society.

"No one knows exactly how these little tubes work or even if they will work 
out in manufacturing, but they are surprisingly good at detecting 
electrical signals," says Kosko. "Once we figure out all the parameters 
that are needed to fine tune them, both physically and chemically, we hope 
to turn these tubes into powerful little antennas."

If all goes well, the tubes could start appearing in consumer products 
within five to ten years, he predicts.

The finding hinges on a well-known but counterintuitive theory called 
"stochastic resonance" that claims noise, or unwanted signals, can actually 
improve the detection of faint electrical signals. Kosko set out to show 
that the theory was applicable at the nano scale.

Under controlled laboratory conditions, Kosko's graduate student, Ian Lee, 
generated a sequence of faint electrical signals ranging from weak to 
strong. In combination with noise, the faint signals were then exposed to 
devices with and without carbon nanotubes. The signals were significantly 
enhanced in the container with the nanotubes compared to those without 
nanotubes, Kosko says.

Although much testing needs to be conducted before the structures are 
proven to be of practical use, Kosko sees big potential for the little 
tubes. He says they show promise for improving "spread spectrum" 
technology, a signal processing technique used in many newer phones that 
allows listeners to switch to different channels for clearer signals and to 
prevent others from eavesdropping.

Arrays of the tiny tubes could also process image pixel data, leading to 
improved television images, including flat-panel displays, according to 
Kosko. The tubes also have the potential to speed up Internet connections, 
the researcher says.

In a more futuristic application, Kosko believes the tubes have the 
potential to act as artificial nerve cells, which could help enhance 
sensation and movement to damaged nerves and limbs. The sensors might even 
be used as electrical components in artificial limbs, he adds.

By adjusting the shape, length and chemical composition of the nanotubes, 
as well as the size of the tube array, they can in essence be customized 
for a wide-variety of electronic needs, Kosko predicts. "There are likely 
many good applications for the technology that we have not foreseen."

Funding for this study was provided by the National Science Foundation.

This story has been adapted from a news release issued by American Chemical 
Society.


73 Ed Tanton N4XY <n4xy@earthlink.net>

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