IT COULD give the term “power suit” a whole new meaning. Getting dressed a few years from now, you may find yourself putting on more than mere fabric. Your clothes may by then sport electronic sensors and tiny computers. As you walk out of the door, you will be not just fashionably attired, but digitally enhanced—a living, breathing node on the internet. This prospect will delight some people and horrify others. But it could actually happen, if the field known variously as smart fabrics, electronic textiles or “washable computing” can achieve the breakthrough its proponents believe is just around the corner.

As recently as five years ago the idea of clothing, furniture and upholstery that combined fabric with electronics was a fantasy. Yet today the first examples of the technology are on sale, with more advanced products on the way. Current products are aimed at early adopters, but both hopeful start-ups and big firms such as Nike, DuPont and Philips are searching for an application that will carry the technology into the mainstream.

Smart fabrics look and feel like ordinary textiles, but can do extraordinary things: generate heat, monitor vital signs, act as switches or sensors, and even change colour. With so much fabric woven into daily life, proponents of smart fabrics see them as a natural way to increase the pervasiveness of today's gadgets and add snippets of intelligence to everyday items. Computing power is already being incorporated into cars, household appliances and entertainment systems, notes Stacey Burr, the boss of Textronics, a spin-off from DuPont based in Wilmington, Delaware, that is developing electronic textiles and clothing. So fabric, she argues, is a natural next step. “About 70% of the materials that people come in contact with are fabrics,” she says. “We want to create fabrics that warm, illuminate, conduct, sense and respond.” Smart fabrics will be particularly useful in the fields of medicine, sports, communications and personal security, Ms Burr predicts.

Material benefits

She is not alone in her enthusiasm. “There is a really big market,” says John Collins of Eleksen, a British start-up that sells sensors based on smart fabrics that can be incorporated into clothing, accessories and furniture. Eleksen has so far sold 70,000 units, but already has firm orders for 600,000 units in 2006, and expects sales to rise tenfold again in 2007.

Smart fabrics can take many forms. The most basic kind is electrically conductive, such as Textronics' “textro-yarn”, a slightly elastic material that resembles ordinary fabric. Because it conducts electricity, it can be used for heating (by passing a current through the fabric), as a radio antenna, for electromagnetic shielding, to provide power to other devices embedded into clothing, and even to make electrodes, for example to monitor vital signs. The company has just launched a sports bra that monitors the wearer's heart-rate and calorie consumption, and displays them on a wristwatch-sized screen.

Another of Textronics' smart materials is “textro-polymer”. Its fibres have the useful property that their resistance changes when they are stretched. This can be used to detect bending, stretching or tugging, which can in turn reveal whether the wearer of a smart garment is moving or stationary, or whether a particular car seat or bed is occupied. In September, Textronics announced a deal with Konarka, a pioneer in flexible solar panels, with a view to making jackets that can recharge mobile phones and other devices.

International Fashion Machines (IFM), a firm based in Seattle, has just launched a range of light switches based on conductive yarns. Squeezing the fuzzy, pom-pom-shaped blob of material changes the amount of current flowing through it. This difference is detected by a control circuit that then turns lights on or off accordingly. Maggie Orth, IFM's founder, hopes these playful switches will find use in children's playrooms and designer hotels.

The smart fabric made by Eleksen, called ElekTex, acts as a more elaborate touch sensor. It consists of three layers: a top and bottom layer of conductive material, and a middle layer that conducts electricity when it is compressed. Voltage gradients are applied across the top and bottom layers, at right angles to each other. When the fabric is pressed, current flows through the middle layer. By measuring the change in voltage across the top and bottom layers, it is possible to determine where (and roughly how hard) the fabric is being pressed. This means that sliding and tracing gestures, as well as individual presses, can be detected.

Eleksen claims that the fabric can survive being washed, crumpled, punctured and even driven over. It has already been used to make roll-up fabric keyboards for handheld computers, to control a heated jacket made by Innovative Sports, and to incorporate iPod controls into ski jackets made by Spyder, Kenpo and Westcomb. The iPod is popped into a special pocket and plugged into a control wire, and it can then be controlled using fabric sensors in the jacket's cuff or on its sleeve. Buttons start and stop playback and select tracks, and stroking a strip adjusts the volume.

Fancy fabrics, clever clothes

In France, a cinema has experimented with using ElekTex to count the number of occupied seats; another proposed use is to incorporate television controls directly into the fabric of sofas. “The real value in our stuff is being able to keep the interface as soft as the thing it's going into,” says Miles Jordan of Eleksen. The company has also devised a second form of smart fabric, again made up of several layers, which functions as a moisture sensor. The top two layers allow only a small proportion of incident moisture to reach the third, bottom layer, which contains a matrix of conductive fibres. The amount of moisture can be determined by measuring variations in the resistance of this layer. This smart fabric can be used for what Eleksen delicately calls “incontinence detection” in medicine, and to detect moisture in buildings.

As well as acting as sensors and switches that gather information, smart fabrics can also function as output devices. One approach is that taken by Luminex, the result of a collaboration between Caen, an Italian electronics firm, and Stabio, a Swiss textiles company. Luminex is a fabric with fibre-optic strands woven into it, which are then illuminated using light-emitting diodes powered by a small battery pack. Luminex has already been incorporated into glowing clothes, safety garments, handbags and furniture, and even a wedding dress.

Electric Plaid, devised by IFM, takes a different approach. Rather than emitting light directly, it contains stainless-steel yarns coated with “thermochromic” inks that, as their name suggests, change colour depending on the temperature. Applying a current causes the yarns to heat up, which changes the ink's colour. This makes possible fabrics with slowly changing patterns (see photo on previous page), and even information displays: a wallhanging that changes colour depending on the weather forecast, for example.

A kinder, gentler light switch

As smart as these fabrics are, they still rely on separate control circuitry to detect pressure, motion or moisture, or change their appearance. Smart jackets based on ElekTex, for example, contain a small control unit to connect the touch sensors on the sleeve to an iPod. Rehmi Post, a researcher at the Centre for Bits and Atoms at the Massachusetts Institute of Technology (MIT), says the real breakthrough will come when the control electronics are not simply housed in clothing, but are woven directly into the fabric. Today's products, he points out, are a halfway-house in which the textiles and electronics are not fully integrated. “They aren't ambitious enough,” he says.

Seamlessly weaving cloth, power and data, Dr Post admits, will be easier said than done. Many of the required technologies exist already, but overcoming problems such as electrical interference, programming and power supplies will not be trivial. “There are a few fundamental problems that have to be solved, but they are solvable,” he says.

Integrating fabrics and electronics more closely will, Mr Collins predicts, make possible phones, music players and other portable devices that are part electronic and part fabric. They will, he says, be smaller, lighter, less power-hungry and more durable than today's devices.

Smart clothing could not only blur the lines between materials and electronics but, if items of clothing start to absorb previously discrete devices, between people and machines. “They will be a kind of second skin—functionality will blend into the background,” says Ms Burr. Perhaps. But in the short term, at least, it seems more likely that smart clothing's appeal will be limited to particular, well-defined situations, such as skiing, policing and emergency rescue. That said, many people now refuse to go out without their mobile phones. The challenge for believers in smart fabrics is to make people feel similarly naked without them.