Nanotechnologists at the University of Texas at Dallas and their colleagues in Australia have already demonstrated their highly electrically conductive ribbons could find use in everything from flexible television screens and solar cells to artificial muscles.

"When we want to try making a device, it's not a difficult task because we can produce a lot of sheets in a very short period of time, so we've been able to advance a lot of applications. And everything is easily scalable," senior researcher Ray Baughman, director of the University of Texas at Dallas NanoTech Institute, told UPI's Nano World.

The researchers started with forests of freestanding multi-walled carbon nanotubes, each roughly 10 nanometers wide and 70 to 300 microns high. They then teased nanotubes away from one side of the forest with a sticky strip of tape, drawing out the entangled nanotubes in long sheets.

Initially these sheets are very airy and porous, but they can quickly get compressed into sheets 360 times denser that remain only 50 nanometers thick.

Scientists have made carbon nanotube sheets before, but the process could take up to a week or lead to sheets that were not transparent or as strong. Baughman and his colleagues can produce 2-inch-wide strips of the airy, porous sheets at up to roughly seven yards per minute, about a third the production rate for commercial wool spinning.

The researchers have already demonstrated their sheets can find use as electrodes for bright organic light-emitting diodes in flat-screen displays. They might also find use in video recorders and solar power cells.

The sheets, which are flexible without losing electrical conductivity, also make a good starting point for artificial muscles, and Baughman and his colleagues report experiments in that vein in a paper appearing in the Aug. 19 issue of the journal Science.

"We hope to go from the very high voltages now used with artificial muscles, some 4,000 volts, which really is a barrier to widespread application, to reduce that voltage down with our nanotube sheets to something more reasonable, like 40 volts," Baughman said.

The nanotube sheets strongly absorb microwave radiation, which causes them to heat up. The researchers employed this property to weld nanotube sheets onto Plexiglas, which affected neither the nanotube sheets' transparency nor their electrical conductivity.

Baughman suggests windows made with carbon nanotubes could serve as heating elements and antennas. Other applications the researchers are exploring include high-strength composites, super-capacitors, batteries, fuel cells and thermal-energy harvesting cells.

"Rarely is a processing advance so elegantly simple that rapid commercialization seems possible, and rarely does such an advance so quickly enable diverse application demonstrations," Baughman said.

Baughman said his team and their Australian colleagues are working together with companies and government labs to bring the nanotube sheets to market. They plan to file five utility patents three months from now, after which they will begin offering their technology to licensees.

"Ray has done some really pathfinding work here," Wade Adams, director of Rice University's Center for Nanoscale Science and Technology in Houston, told Nano World. He noted his team can also make forests of freestanding single-walled carbon nanotubes is collaborating now with Baughman to make similar sheets.

"Nanotechnology has been hyped a lot with many great expectations of products that will change the world. One example often given is invisible sunblocker, which does the same job but you can't see it. But that's cosmetic. It hasn't really changed the world," Ned Thomas, a materials engineer at the Massachusetts Institute of Technology in Cambridge, told Nano World.

"With these carbon nanotube sheets, it might not be too long before you see them in laptop screens and cell phones. Then you'll have some profits and some companies actually hiring people, and point to these sheets and not sunblock as the nanotechnology breakthrough of the year," Thomas added.

He said future experiments might consider coating nanotubes with a variety of chemicals before bundling them into sheets in order to keep from them sticking or to develop entirely new material properties.

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