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Electronic Textiles Charge Ahead

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Science  15 Aug 2003:
Vol. 301, Issue 5635, pp. 909-911
DOI: 10.1126/science.301.5635.909

Clothes may soon change color on command, give you a checkup, and communicate by Wi-Fi, say researchers striving to give fabrics a dose of dyed-in-the-wool smarts

Computer geeks aren't much for setting fashion trends. You know the stereotypes: clothes rumpled from sleeping on a departmental lounge sofa, a pizza stain here and there. But in yet another example that life loves a good twist of irony, a growing cadre of computer, electronics, and textile researchers are poised to revolutionize the fashion world, and perhaps at the same time the fields of communication, medicine, advertising, and even warfare. The rumpled-shirt crowd is looking to give the decidedly low-tech world of textiles a good dressing up, electrifying everything from jackets and T-shirts to advertising displays and carpets with electronic sensors, processing chips, and displays.

Wall of sound.

Textile-based sensor nets could enable army units to triangulate the location of opposing forces.

CREDIT: USC INFORMATION SCIENCES INSTITUTE

The first results are already on store shelves, such as a snowboarding jacket designed to play MP3 music files with the help of controls stitched onto the sleeve. But most applications in the emerging field of electronic textiles are still being wired up. A Georgia company, for example, is creating a shirt designed to monitor a patient's vital signs and alert a doctor by means of a wireless signal at the first sign of trouble. The U.S. military is looking into fabric-based sensor nets for help in identifying the approach of enemy tanks and other vehicles. And a German computer chip company is creating carpets capable of detecting intruders and fire.

“The number of potential applications for e-textiles is tremendous,” says Sungmee Park, an e-textile designer at the Georgia Institute of Technology (Georgia Tech) in Atlanta. Major electronics and materials companies such as Philips, DuPont, and Foster-Miller are flocking to the field. One DuPont survey estimated that in 5 years, e-textiles designed to monitor patients' medical conditions could pull in anywhere from $100 million to $1 billion.

But discounting the hype and bandwagon effect that follow any new technology, many experts caution that ironing the bugs out of advanced e-textile applications will likely take some time. Researchers must find ways to integrate flexible wires into clothing; link them to electronics that can withstand bending, twisting, and stretching; and power the whole ensemble. Only then will geek chic become truly prêt-à-porter.

Power suit

Inventors began integrating electronics and textiles about 80 years ago, when doctors pushed rudimentary electric blankets to encourage tuberculosis patients to sleep outside in fresh air. The blankets were little more than a resistive heating coil stitched between twin sheets of fabric. Modern e-textiles, by contrast, weave conductive threads right into fabrics themselves, making them often indistinguishable from traditional fabrics.

So far, applications have ranged from the mundane to the gimmicky. In an update of the old idea, Robert Rix, a British inventor, has turned out a line of carbon-based textiles called Gorix, now incorporated in everything from scuba diving suits to car seat covers, that carry a small electric current throughout the fabric where the power is converted to heat. SOFTswitch, based in West Yorkshire, U.K., manufactures a foldable touch-sensitive fabric keyboard and mouse that can connect to a personal digital assistant (PDA) and cell phone. Among other showpiece projects, Margaret Orth and colleagues at International Fashion Machines in Cambridge, Massachusetts, have designed a “firefly” dress wired with 50 light-emitting diodes, and electronic tablecloths that let dinner guests play Jeopardy.

Snow tunes.

A ski jacket wired with an MP3 player and controls on the sleeve means no more fumbling with gloves.

CREDIT: BURTON SNOWBOARDS

The loudest buzz in the field centers on e-textiles that sense and report on their surroundings. In 1996, for example, Park and Georgia Tech textile engineer Sundaresan Jayaraman launched the field of medical textiles by incorporating current-carrying fibers into fabrics to power electronic sensors that monitor the wearer's breathing, temperature, and heartbeat. The pair created what Jayaraman calls a wearable motherboard, a wired shirt into which off-the-shelf monitors can be plugged in and later unplugged so the shirt can be washed. In 2000, Georgia Tech licensed the technology to a company called Sensatex for commercialization.

Sensatex is now developing its medical monitoring SmartShirt, which can relay information wirelessly to doctors. The wearable monitors could also help emergency officials track the health of firefighters and other emergency crews and give personal trainers a way to monitor the condition of top athletes, Jayaraman says. Although cheap wristwatch-style heart rate monitors already exist, Jayaraman says that shirt-based monitors will be far more versatile, capable of working with a wide variety of sensors that can track body temperature, oxygen, and perhaps someday even blood glucose levels.

Like earlier emerging technologies, sensor-studded e-textiles could find their first niches in combat. According to Robert Kinney, the director for individual protection at the Natick Soldier Center in Massachusetts, the U.S. military is evaluating wearable sensors to monitor soldiers in the field and to help medics conduct battlefield triage. Other military labs hope to adapt e-textiles for remote sensing. Under contract with the Defense Advanced Research Projects Agency, researchers at Virginia Polytechnic Institute and State University (Virginia Tech) in Blacksburg and the University of Southern California, for example, have been developing an acoustic sensor fabric designed to pinpoint the location of enemy vehicles. With copper wires and a network of microphones woven inside, the sensor fabric is designed to compute the difference in time of arrival of a sound to different sensors in the network. A processing chip can then triangulate the origin of the signal. The use of e-textiles, says Virginia Tech electrical and computer engineer Tom Martin, could allow the military to incorporate fixed-sensor networks into everything from tents to parachutes.

Meanwhile, researchers at the Natick Soldier Center are pursuing a variety of nonsensing e-textile efforts. They are working to stitch communications antennas into vests worn by soldiers in hopes of eliminating the 3-meter wire antennas that can make a soldier carrying a radio an obvious target. In another project, researchers at WRONZ EuraLab in the United Kingdom have contracted to develop a soft fabric keypad on a jacket sleeve that can replace heavy, bulky communications keyboard controls for field units. And researchers at Konarka Technologies in Lowell, Massachusetts, are working with Natick to develop flexible solar cells that can be incorporated into tents and other fabrics to help power the burgeoning number of electronic gadgets soldiers now carry.

Wired wear.

Light-emitting diodes make “firefly dress” (top) sparkle like its namesake, and researchers hope that medical-monitoring shirts (bottom) will become lifesavers.

CREDITS: (TOP TO BOTTOM) MAGGIE ORTH (1998); 2002 SENSATEX INC.

Kinney says that military experts are counting on commercial interest to drive down manufacturing costs. Besides wearable music players, Orth and others say that e-textiles could find burgeoning demand in the areas of advertising, security systems, and even interior design. Orth, for example, has created color-changing electronic textiles that have been exhibited in private homes and the Cooper-Hewitt National Design Museum in New York City. Orth's fabrics consist of thin metal wires wound into yarn coated with thermal chromic inks that change color when heated. When the juice is turned on, Orth's fabric swatches can make a rainbow of color combinations, changing from black to red or white to blue. Such chameleon materials hold enormous potential for interior designers and advertisers, Orth says, by making it possible to craft displays on everything from walls to carpets. German chipmaker Infineon Technologies is also developing carpets wired with sensors to detect pressure, vibration, and temperature for advanced security and fire detection systems.

Beyond prototypes

For all their promise, wired fabrics still face a bevy of technical and financial obstacles. Among the greatest technical hurdles is simply withstanding everyday wear and tear. “Particularly for military applications, durability will always be an issue,” Kinney says. In e-textiles, routine bending and stretching that cause normal fibers to fray and tear over time could break wires, causing a sensor or electrical connection to fail. As a result, e-fabrics must be carefully designed with redundant circuits. Orth favors using yarns spun to contain four or more ultrathin wires, so if one breaks the e-textile still functions. Other groups, she points out, prefer incorporating multiple flexible conductive polymer strands, although these often can't transmit as much current as metals.

Chameleon cloth.

When the juice is flowing, heat-activated thermal-chromic inks make patches of this “e-plaid” change color.

CREDIT: 2003 IFM INC.

Another challenge comes from the connectors that link wires, chips, and sensors. “None of those USB or pin connectors in the back of your computer were designed to be worn or thrown in a mud puddle,” Kinney says. As a result, he says, his team spends much of its time coming up with novel connectors able to work with clothing. One example, he says, is a plastic buckle that Natick researchers have designed that not only fastens garments together but also creates an electrical connection between metal pads on the buckle's two interlocking pieces.

Such demonstrations are useful, Orth says. But she adds that the field will remain fragmented until there are common standards for e-textile wires, sensors, chips, and connections. “Every time we do something, it's got to be designed from scratch,” she says. That means that for the foreseeable future, electronic fabrics will likely remain expensive and therefore used for small niche applications. “This will never take off if we have to build a custom garment for every person,” Martin says. Jayaraman insists that modern textile manufacturing techniques will ultimately have little trouble in incorporating whatever wires and devices garmentmakers settle on. But to drive the commercial market, “we still need to find the killer app,” he says.

Martial music?

Keypads akin to this soft-fabric piano could help soldiers communicate.

CREDIT: ITN ENERGY SYSTEMS

Perhaps the most fundamental hurdle for electronic textiles is power. Carpets and other fixed fabrics can plug into conventional outlets. But wired clothing and other mobile e-textiles will have to rely on batteries. For anyone who has lugged a laptop and its kilogram battery around an airport, the prospect of weighing down a lightweight parka isn't too appealing. “Batteries are a huge problem in wearable electronics,” says Orth.

Fortunately, lighter power sources may be on the way. One is a slimmed-down version of the lithium batteries that now power everything from laptops to cell phones. One company, Infinite Power Solutions (IPS) in Golden, Colorado, is making lithium batteries just micrometers thick that are essentially painted on metal foils. Such batteries, says IPS marketing director Joe McDermott, could be incorporated into the lining of garments to power sensors and logic chips as well as on the surface of backpacks and other fabrics used in everyday life. Upon returning home, McDermott says, we may one day plug in our backpacks or even jackets much as we do with cell phones and PDAs today.

Researchers at Littleton, Colorado-based ITN Energy Systems, the former parent company of IPS, hope to make future batteries even sleeker, incorporating them right into textiles themselves. The company is currently designing fiber-based batteries, each of which layers the traditional anode, cathode, and electrolyte right on top of a 100-micrometer-wide fiber that's incorporated into a textile. At this point, the ITN researchers have shown only a proof of concept that it's possible to layer the battery materials on curved fibers. And McDermott says that the team remains some 3 to 4 years from incorporating their PowerFibers into a working e-textile product. Still, he adds, the hope is that textilemakers will be able to weave fiber batteries into garments the same way that they add different colored threads today. McDermott says it's likely that battery fiber fabrics won't weigh any more than traditional textiles.

Power patch.

Current-generating materials layered atop individual fibers could pave the way for textile-based batteries.

CREDIT: SOFTSWITCH LTD.

With so many hurdles ahead, your closets probably won't be bulging with e-textiles anytime soon. But most experts say their time is bound to come. “There is not a doubt in my mind you're going to see a continued miniaturization of the technology and its integration into fabrics,” Kinney says. “This is the future.”

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