For many years, scientists have thought tiny, supertough molecules known as carbon nanotubes would be the ideal building blocks of next-generation microdevices such as semiconductors, which will be orders of magnitude smaller than today's electronic components. But the more scientists learn about the properties of nanotubes, the harder it is to predict exactly how they can be used.

In the Mar. 10 issue of Science, researchers at the University of California at Berkeley and Lawrence Berkeley National Laboratory report that single-walled carbon nanotubes are extremely sensitive to oxygen. That means that if they are ever used in electronic components, the devices may not perform well in normal, nonvacuum environments. "There could be problems if you think of these as room-temperature devices," says Berkeley theoretical physicist Marvin Cohen, who collaborated with the authors of the report. Cohen predicts the nanotubes' sensitivity to oxygen and other gases may earn them a role in various new types of sensors.

But even if gas sensitivity or other properties foil scientists' attempts to construct defect-free carbon nanotubes, the whole architecture for chips built on the atomic scale may be so different that defects in individual elements won't matter much. "If we spend all our time making things perfect at the nano level, nobody will ever make any money," says Meyya Meyyappan, senior scientist for nanotechnology at the NASA Ames Research Center. "There are going to be defects, and we must learn to get along with them."

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