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Nanotechnology--Waiting For Applications for Carbon Nanotubes

© Linda Mamassian

Carbon nanotubes have been intensely studied in recent years. Their unique properties promise to revolutionize our technology in the near future, but there are few affordable applications so far. Let's look at some of the possible uses of this new class of material.

Discovered in 1991, nanotubes are made up of sheets of carbon atoms rolled into tubes and capped with half a buckyball at each end--kind of like a rolled-up sheet of chicken wire with half a soccer ball at each end. These long molecules are 30 nanometers or less in diameter (about 1/50,000th as thick as a human hair--a nanometer is one billionth of a meter). Their length may exceed 100 micrometers.

Properties
Nanotubes are lightweight (one sixth the weight of steel) but are one of the strongest materials known--up to 100 times stronger than steel. They are able to stand repeated bending, buckling, and twisting without breaking. The electrical conductivity of nanotubes depends on the arrangement of carbon rings in the tube. If the hexagons line up parallel to the long axis of the tube, a nanotube will conduct electricity better than copper or gold. If the hexagons spiral around the tube (like stripes on a candy cane or barber pole), the nanotube will be a semiconductor, like the silicon semiconductors used in computer chips.

Applications
Nanotubes are already used in plastics for the automotive and computer industry to conduct electricity away from sensitive components and prevent static electricity from building up. They are also used in to improve the sensitivity of scientific instruments. They have been used in scanning tunneling microscopes and atomic force microscopes to help scientists see detailed structures of proteins and other molecules.

Widespread use of nanotubes in computers is possible within a few years. According to estimates in the semiconductor industry, we will reach a physical limit in shrinking silicon-based transistors within five to ten years. Computers that use nanosized carbon-based wires, transistors, and diodes would be much smaller and faster than anything available today.

Nanotubes can also be used in reflective materials. Possible uses include heat reflective materials, electromagnetic shielding for cell phones and laptop computers, and radar absorption for stealth aircraft.

In the near future, nanotubes will be used in electron guns for flat screen television, computer monitors and display lighting elements.

Possible medical uses in treating cancer, AIDS, and other diseases. Little research has been done because of high cost and concerns about possible toxicity. (Carbon nanotubes are similar in size and many physical properties to asbestos fibers.)

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