Electrotextiles may one day bring us body-monitoring shoes and bomb-detecting sheets, but for now, technology developers must tie up a few loose threads.

Electronic textiles or “electrotextiles” are promising to jazz up everything from shoes to shower curtains. Made from such wire- and electronic device-woven fabrics, footwear may soon tell us how fast we’re running or how rapidly our heart is racing. Curtains could change hues, and shirts could play music.

Indeed, at the Materials Research Society meeting in Boston last month, e-textiles were all the rage. In fact, aside from being the next fashion craze or curiosity, these fabrics also have crime-stopping potential. Laid out in walkways or buildings, large-area e-textiles can record footfalls, detect biochemical agents and nab smugglers.

And for the U.S. military, these e-fabrics—which can collect environmental and biomedical data—could mean superior protection for future soldiers from enemies and the elements.

But there are still wrinkles to iron out. For one, e-fabrics are too stiff to be wearable. “I’m sick of looking at e-textiles that are circuits, and not textiles,” says Maggie Orth, CEO of Massachusetts-based International Fashion Machines (IFM), an MIT Media Lab startup that’s working on e-textiles.

The conductive fibers in these textiles must not only bend and bunch, like that of any cloth, but also withstand the turbulence of a washing machine, the jabbing of a sewing machine needle and the snapping of threads.

And with all these concerns collaring in the technology, many at the MRS meeting concede that e-textiles may be more useful for industry than for apparel.

Even researchers from DARPA, the U.S. Defense Advanced Research Projects Agency, admit that currently e-textiles would be as impractical for soldiers in warfare as suits of armor.

Instead, DARPA researcher Elana Ethridge suggests using e-fabrics in battlefield parafoil, a parachute-like material found in kites and paragliders. A parafoil made from e-textiles would be much more precise, she says, adjusting to fluctuating winds and temperatures by changing shape or texture, for steering.

And because electrotextiles may be able to do more than receive and transmit electrical signals, Ethridge sees their potential in explosion detection. In fact, DARPA is developing a sheet interspersed with sensors that can be rolled out like a tarpaulin to protect certain areas. Such sensor-studded sheets could detect nearby explosions, sense biochemical agents and even activate the shutdown of affected areas.

In earthquake zones, says Ethridge, these large-area e-fabrics could tell us how well a building or other structure is holding up.

In addition, they could be spread out just below a street or pavement to keep tabs on vehicle or pedestrian traffic because they can be made as long as required, says John Muth, an associate professor at North Carolina State University in Raleigh.

However, these tarpaulin-like e-textiles and embedded sensor arrangements also pose some technical problems. For example, in a sensor-studded smart carpet, “signal attenuation (or reduction in strength) and the ability to form reliable interconnections present serious challenges,” says Muth.

Present telecommunications standards could take care of radio frequency interference and other concerns, says Muth. In addition, he says, engineers could develop fabrics composed of several layers—just like current microprocessors and circuit boards—”to incorporate power and data transmission on different levels.”

Another snag in e-fabric development is the shortage of flexible display technologies, says Orth from IFM, which is talking to Nike about making training sneakers that monitor your heart rate, hydration, blood sugar levels and even your running speed by changing color. “We have the means to collect and transmit the data, but not to display it,” she says.

Fortunately, Orth’s shoes may be given a running start by a new development at the Xerox Research Centre of Canada (see Are Silicon’s Days Numbered?). Chemist Beng Ong and colleagues have recently developed printed organic electronic transistors that he says are durable enough to supplant the silicon integrated circuits in LCDs. And these transistors are likely to be featured in monitors and other devices within three to five years.

In fact, such organic circuits, which can be sprayed on thin plastic sheets, may be just what we need to make flexible gadgets like roll-up televisions.

“When the electronics become flexible enough that we can watch videos on the backs of people’s T-shirts, then we’ll really have something to talk about,” says Raymond Oliver, a senior research fellow at Imperial Chemical Industries.

For now, we’ll have to wait a few seasons for chameleon shirts, smart underwear and toasty, thermal garments.

Sources: Shoes and Sheets Get Wired
Philip Ball
Nature, Dec. 6, 2002
http://www.nature.com/nsu/021202/021202-11.html

E-Fabrics Still Too Stiff to Wear
Mark Baard
Wired News, Dec. 5, 2002
http://www.wired.com/news/technology/0,1282,56708,00.html