Multifunctional Fabrics See the Light

For electronic and optoelectronic devices to function, conducting, semiconducting, and insulating materials need to make intimate contact. Typically, electronics makers use an elaborate collection of processes to stick wafers of different materials to one another and create devices. Now, MIT researchers Mehmet Bayindir, Yoel Fink, and colleagues have taken a cue from fiber-optic makers and developed an easy way to draw these materials together into long, flexible fibers [Nature, 431, 826 (2004)].

The researchers start with a cylinder 20 cm long and 35 mm in diameter. This cylinder has the same geometry as the desired fiber—with concentric layers of conducting low-melting crystalline tin, amorphous semiconductors As-Se-Te-Sn and As₂Se₃, and polymeric insulators polyetherimide and polyethersulfone. The team heats this cylinder in a furnace and draws it out into fibers. This drawing process brings the materials into intimate contact, creating a fiber that can conduct both photons and electrons.

These metal-insulator-semiconductor fibers can then be woven into a grid that, with only a few fibers, is able to identify the location of a point of light. Smart spectrometric fabric woven from these fibers, Fink explains, could be used as a new type of interface for a computer screen or projection board. “Instead of having a mechanical mouse,” he says, “you could just use a light beam, like a laser pointer, to communicate with the computer because the screen would know where it was being hit.”