Oh carbon nanotubes, is there anything you can't do?
Nanotubes can be envisioned as one-atom thick sheets of carbon that have been rolled into tubes. Researchers know that when things get that small, they act a little weird, and labs around the world are now racing to capitalize on nanotubes' strange properties. With their extraordinary strength and fascinating knack for conducting electricity and heat, nanotubes are finding applications in everything from cancer treatments to hydrogen cars. These structures of carbon may be tiny—a nanotube's diameter is about 10,000 times smaller than a human hair—but their impact on science and technology has been enormous.
Here, we count down nine of the most enticing possibilities for these giants on the Lilliputian stage. They probably won't all pan out, but if nanotubes fulfill just a few of these predictions, they'll be worth the buzz.
9. X-traordinary X-rays
A new nanotube-based imaging system could take sharper, faster pictures that trump today's X-rays and CT scans. Researchers from the University of North Carolina say their device will be especially useful for imaging organs that are perpetually in motion, like the heart and lungs.
In a traditional X-ray machine, a filament emits electrons when it is heated above a certain threshold, and those electrons fly through the body and hit a metal electrode on the other side, creating images; CT scans produce three-dimensional images by rotating the electron source. But the new system uses an array of carbon nanotubes that emit hundreds of electrons simultaneously as soon as voltage is applied to them. The system is faster than a regular X-ray machine because there are no filaments to warm up, and the multiple nanotube emitters can also take pictures from many different angles without moving.
8. Helping the Hydrogen Car
Cars powered by hydrogen fuel cells have been a clean energy dream for years, but they've been held back largely by the expense of making fuel cells. The Department of Energy estimates that half of a fuel cell's price tag comes from the platinum catalyst used to speed up the reaction that produces energy. But in February a team of researchers found that bundles of carbon nanotubes doped with nitrogen form a more efficient and more compact catalyst.
While carbon nanotubes are currently fairly expensive to produce, researchers note that the price has been plummeting. Researchers from the University of Dayton, Ohio note that nanotube production costs have fallen 100-fold since 1990, while no such price reductions are likely with platinum, a limited natural resource.
7. Diagnosis Via Nanotube
Spanish researchers say nanotubes can even help with an embarrassing medical problem, and have created a biosensor that can diagnose yeast infections (the irritating fungal infections that can take hold on the genitals). The scientists say their gadget provides a quicker diagnosis that today's typical method, in which a cell sample is taken and cultured in the lab to look for the presence of the Candida albicans fungus.
The researchers built a transistor that contains carbon nanotubes and antibodies programmed to attack the Candida yeast cells. When a cell sample is put on the biosensor, the interaction between the yeast and the antibodies changes the electric current of the device. The extremely conductive nanotubes record the change and allow researchers to measure how much yeast is present.
6. The Smallest Chips in the Land
Nanotubes could even spell the end of a building block of our modern world: the silicon-based computer chip. Several research groups have found ways to "unzip" carbon nanotubes to produce atom-thick ribbons of graphene. Like silicon, graphene is a semiconductor, but the nano-sized ribbons could be used to pack much more processing power on every computer chip.
Researchers have made graphene ribbons before, but never as easily—previously the ribbons were cut from larger graphene sheets, which offered little control over their size and shape. In contrast, unzipping nanotubes is a precise process. One research group first stuck the nanotubes to a polymer film, then used argon gas to etch away a strip from each tube to produce the nanoribbons.
