There's a major movement going on in the electronics and computer industries to develop wearable devices for what's being called the post-PC era. We are now at the dawn of that era, and some of these devices are already making their way to the consumer market. Despite the small size and portability of these devices, they are still noticeable and aren't always very aesthetically pleasing. The next phase of this post-PC era will be to integrate computers and other devices directly into our clothing, so that they are virtually invisible.

Photo courtesy MIT Media Lab researchers Josh Strickon, Rehmi Post, Josh Smith, Emily Cooper and Maggie Orth
Using conductive fibers, MIT Media Lab created the Musical Jacket, which is being marketed by Levi in Europe.

In the next few years, we might be filling our closets with smart shirts that can read our heart rate and breathing, and musical jackets with built in all-fabric keypads. Thin light-emitting diode (LED) monitors could even be integrated into this apparel to display text and images. Computerized clothes will be the next step in making computers and devices portable without having to strap electronics to our bodies or fill our pockets with a plethora of gadgets. These new digital clothes aren't necessarily designed to replace your PC, but they will be able to perform some of the same functions.

Computerized clothes are the ultimate in portable high-tech gadgetry. In this edition of How Dewsoft Stuff will work, you will learn just what these clothes are made of, who is making them and what kind of products we might be wearing in the coming decade.

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.

Tomorrow's E-Wardrobe
The development of digital yarn opens up the opportunity for an entire computerized clothing industry. In the next decade, we will likely see a wide range of digital apparel enter the consumer market. Several companies are already exploring the possibility of putting us in designer computerized clothing, including
IBM, Levi, Philips, Nike and SensaTex. In Europe, Levi is already test marketing the musical jacket developed by the MIT Media Lab.

Levi's musical jacket is made with the silk organza and is controlled with an all-fabric capacitive keyboard. This keyboard has been mass-produced using ordinary embroidery techniques and conductive thread. The keypad is flexible, durable and responsive to touch. A printed circuit is used to give the keypad a sensing ability, so that the controls react when pressed. The keypad can sense touch due to the increase in capacitance of the electrode when touched. The keypads are connected to a miniature MIDI synthesizer that plays music. Power could be supplied by a parasitic power source such as solar power, wind, temperature or mechanical energy from turning wrists or walking. Further out, researchers are looking for fabrics capable of generating power as they flex.

Photo courtesy MIT Media Lab
This keypad controls Levi's musical jacket and is made completely with fabric, even the wiring.

Another all-fabric keyboard being developed by the MIT Media Lab uses conductive and non-conductive material sewn together in a row- and column-addressable structure. The final product looks like a quilt that's been pieced together in a square pattern. The quilted conductive columns are insulated and form the conductive rows with soft, thick fabric, like felt or velvet. Holes in the insulating fabric allow the row and column conductors to make contact when a user presses down on the keyboard. Shirts and other clothes using this keyboard can be thrown in the washing machine just like an ordinary piece of clothing.

Photo courtesy MIT Media Lab
MIT Media Lab's all-fabric, switching-contact keyboard is washable.

While the musical jacket is an example of how computerized clothing could be used for entertainment, researchers at the Georgia Institute of Technology have developed a practical, medical purpose for this technology. The smart shirt can monitor both heart and breathing rates by using optical and electric conductive fibers that are woven into the fabric of the shirt.

The smart shirt project at Georgia Tech was originally financed by the U.S. Navy, beginning in 1996. At that time, the shirt was being designed for soldiers in combat, so that medical personnel could find the exact location of a bullet wound. To pinpoint the location of bullet penetration, a light signal is continually sent from one end of the optical fiber to a receiver on the other end. This fiber is also connected to a personal status monitor worn on the hip. If the light from the emitter does not reach the receiver inside the monitor, this signals that the soldier has been shot. The light signal then bounces back to the point of penetration, which helps doctors find the exact location of the bullet wound.

Photo courtesy SensaTex Inc.
An early prototype of the smart shirt developed at Georgia Tech

Wearers of the device attach sensors to their body, pull the shirt on and attach sensor to the smart shirt. The shirt also tracks vital signs, such as heart rate, body temperature and respiration rate. These measurements are monitored in two ways -- through the sensors integrated into the shirt and the sensors on the wearer's body, both of which are connected to the monitor on the hip. Because of it's capability to monitor these vital signs, the shirt is being marketed as a way to prevent sudden infant death syndrome (SIDS). Athletes may also be interested in it to track their body's performance during training and competition.

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