Weaving the Digital Fabric
As with all clothes, computerized apparel starts with the proper thread. Cotton, polyester or rayon don't have the needed properties to carry the electrical current needed for digital clothing. However, metallic yarns aren't new to the clothing industry. We have seen these metallic fabrics worn to make fashion statements for years. Researchers at MIT's Media Lab are using silk organza, a unique fabric that has been used to make clothes in India for at least a century.
 Photo courtesy MIT Media Lab A micrograph of silk organza. You can see the copper foil that is wrapped around the horizontal threads. |
Silk organza is ideal for computerized clothing because it is made with two fibers that make it conducive to electricity. The first fiber is just an ordinary silk thread, but running in the opposite direction of the fiber is silk thread that is wrapped in a thin copper foil. It's this copper foil that gives silk organza the ability to conduct electricity. Copper is a very good conductor of electricity and some microprocessor manufacturers are beginning to use copper to speed up microprocessors.
The metallic yarn is prepared just like cloth-core telephone wire, according to the MIT researchers. If you cut open a coiled telephone cable, there's usually a conductor that is made out of a sheet of copper wrapped round a core of nylon or polyester threads. Because metallic yarn can withstand high temperatures, the yarn can be sewn or embroidered using industrial machinery. This property makes it very promising for mass producing computerized clothing.
Not only is silk organza a good electrical conductor, but it's fiber's are spaced with the right amount of space, so that the fibers can be individually addressed. A strip of the fabric would basically function like a ribbon cable. Ribbon cables are used in computers to connect disk drives to controllers. One problem with using silk organza would result if the circuits were to touch each other, therefore MIT scientists use an insulating material to coat or support the fabric.
Once the fabric is cut into a desirable shape, other components need to be attached to the fabric, like resistors, capacitors and coils. These components are sewn directly to the fabric. Additional components, such as LEDs, crystals, piezo transducers and other surface mount components, if needed, are soldered directly onto the metallic yarn, which the developers say is an easy process. Other electronic devices, can be snapped into the fabric by using some kind of gripper snaps, which pierce the yarn to create an electrical contact. These devices can then be easily removed in order to clean the fabric.
 Photo courtesy MIT Media Lab A circuit fabricated on silk organza fabric |
At Georgia Tech, researchers have developed another kind of thread to make smart clothes. Their smart shirt, which we will look at in the next section, is made of plastic optical fibers and other specialty fibers woven into the fabric. These optical and electrical conductive fibers will allow the shirt to wirelessly communicate with other devices, transferring data from the sensors embedded in the shirt.
