Spider silk is among the strongest materials known, but an artificial version whose strength matches the original's has proven difficult to produce commercially. Now spider experts at the University of Oxford, England, have developed a device they believe holds promise for breaking that barrier by mimicking arachnoid spinning. The researchers have founded a company, Spinox, to commercialize the technology. Starting with proteins from silkworms, the device produces highly lustrous fibers only about 15 to 20 micrometers in diameter. Spinox's device uses a special membrane to mimic the conditions in a spider's silk-making organ; under these conditions, the proteins self-assemble into nanofibrils. Making larger fibers out of the nanofibrils is simple, says cofounder David Knight: "You just pull it out of the device. The molecules stick together in the actual device and come out as a beautiful thread." Possible uses include medical implants, safety belts, composite materials for car body parts, protective clothing, durable sneakers-just about anything that could benefit from an ultrastrong, superlight material, Knight says. The researchers are working to refine the spinning device and believe that artificially spun fibers as strong and flexible as spider silk could be on the market in three to five years.