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Reinventing the lightbulb, with nanotubes

Researchers create a prototype bulb with a carbon nanotube in place of the standard tungsten filament. It uses less power, burns brighter and could lead to the first major overhaul in bulb design in a century.

Someday, carbon could light up your house.

Researchers at China's Tsinghua University and at Louisiana State University have developed a prototype lightbulb that replaces the standard tungsten filament in lightbulbs with a carbon nanotube.

The nanotube bulb uses less electricity and burns brighter than conventional bulbs. Theoretically, this could lead to the first major overhaul in the design of lightbulbs in more than a century. The results were published in Applied Physics Letters and reported first by PhysicsWeb.

Carbon nanotubes are emerging as one of the miracle materials for the future. Stronger than steel and better at conducting electricity than most metals, the tubes--made up of hexagons of carbon--could eventually be used to create dense memory chips; stronger aircraft parts; and lighter, more efficient electrical power lines, researchers believe.

Because of the complexity of manufacturing and manipulating nanotubes, most of the potential applications listed above won't appear for years, if ever. Still, some companies are already starting to incorporate nanotubes into polymers and coatings to create stronger plastic panels and noncorrosive paints.

Jinquan Wei at Tsinghua, and Bingqing Wei, a Tsinghua alum working at LSU, soaked bundles of nanotubes in an alcohol solution and assembled the tubes into long filaments. The two then replaced a tungsten filament in an ordinary 40-watt bulb with the carbon one.

Among other findings, the team determined that the carbon filament would begin to emit light at a lower voltage threshold, 3 to 5 volts versus 6 volts. They also found that the bulb could operate at 25 volts for 360 hours.

Wei predicted such bulbs could hit the market in three to five years, PhysicsWeb reported.

Light and length have been the subject of other nanotube research projects. In 2003, IBM and some university labs demonstrated that nanotubes could emit light. Researchers at Stanford, Duke and other universities have also come up with ways of creating relatively long nanotubes as well as aligning the tubes into larger structures.