National Geographic : 2006 Jun
The nail on your little finger is about ten million nanometers across. hurrying to get a foot in the door. A Korean com pany has used nanosilver-based antibacterials in refrigerator interiors. The same material can be incorporated in bandages. The hope is the same on all fronts: to get the jump on a grow ing global market that the National Science Foundation estimates will be worth a trillion dollars by 2015. One reason for the rapid global spread of nanotechnology is that the entry cost is com paratively low. Countries that missed out on the computer revolution because they lacked the capital to build vast, high-tech factories that make silicon chips are less likely to miss the nanotech wave. "It's science you can do in a beaker," says Stephen Empedocles, vice president of Nanosys, a company that's developing cheap solar nano structures. Traditionally, the manufacture of solar-energy cells has required a multimillion dollar fabrication facility that cooks sheets of glass at extremely high temperatures until the atoms order themselves into a receptive lattice work. Solar nanostructures, on the other hand, grow like rock candy. You can "mix them up in a beaker with a hundred dollars' worth of starter chemicals," Empedocles says, and then paint them on window glass to turn an entire build ing into a solar-energy generator. Or, they might END OF THE RAINBOW Exposed to ultraviolet light, quantum dots of cadmium selenide look blue, green, or yellow when two to four nano meters wide; slightly larger dots appear orange or red. Because some materials change physical characteristics at the nanoscale, scien tists and entrepreneurs are scrambling for a stake-and profits-on the technology's rapidly expanding frontier. 104 NATIONAL GEOGRAPHIC . JUNE 2006 be embedded in the plastic body of a cell phone or laptop computer. For a hundred dollars, in fact, anyone can buy nanoparticles-specifically a gram of car bon nanotubes-online. Place the order, and you'll receive a small ziplock bag of what looks like soot tucked inside a cardboard FedEx enve lope along with some safety instructions. (They recommend gloves to keep the carbon slivers off the skin and a respirator to keep the tiny black specks from entering the lungs.) There's not much you can do at home with a thimbleful of carbon nanotubes. But some of their mysteries are revealed in another Rice Uni versity lab, where Matteo Pasquali holds up a test tube containing a few dark threads so stiff that they seem to have been starched and ironed. These are fibers spun from carbon nanotubes several billion of them-which, in theory, should be stronger than Kevlar, the material in bullet proof vests. For now, however, the threads are only about as tough as the acrylic found in an ordinary sweater. The reason the threads are weak, Pasquali believes, is because some portion of the billion nanotubes bundled together have hidden breaks. A photo taken through a micro scope shows fibers that look like pale gray hairs, some perfectly straight, others frayed and curling.