Air knocks the wind out of nanotubes

Many scientists think that carbon nanotubes may be central to miniature technologies of the future. Because nanotubes conduct current and emit electrons, they have been considered promising as wires, sensors, and display elements. A new study, however, throws some cold water on this optimistic scenario.

Alex Zettl and his colleagues at the University of California, Berkeley have shown that the electronic properties of nanotubes are sensitive to oxygen. In a vacuum, the electrical resistance of nanotubes is 15 percent higher than in air. The researchers report their findings in the March 10 Science.

While this property suggests that nanotubes would make good oxygen sensors, the variability might limit their usefulness in other applications, the researchers say. Since most studies on nanotubes have used samples exposed to air and possibly other contaminants, “the results of those measurements must be carefully reevaluated before firm conclusions are drawn,” the researchers say. In other words, what seem to be intrinsic properties of nanotubes might in fact be due to environmental factors.

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