Smart Fibres
Electronics
Simulation showing significant transfer of material to the probe tip of an atomic force microscope. (click to enlarge)
In the 1990's, the electronic industry was revolutionised. Devices of all sorts became smaller and more powerful than ever before. The public's growing dependence on mobile devices created a need for lightweight electronic equipment. Because textiles are strong, flexible, lightweight and able to conform to almost any shape, it seemed logical to marry textiles with electronics to produce revolutionary new products to meet this demand.
Electronically conductive textiles were produced by using thin wires of various metals in woven and knit constructions. Semi-conductive fabrics were produced by impregnating knit, woven or nonwoven fabrics with carbon or metal powders. These fabrics were used in a variety of applications but they worked passively. By the late 1990's, it was apparent that a whole new genre of textile products was a possibility – fabrics that had an electrical network integrated into their structure that would interact actively with the surrounding environment. The conductive network within a fabric could be designed to sense, respond and adjust to stimuli such as pressure, temperature, or an electrical charge. The new interactive fabrics were termed "smart textiles." These, in theory at least, would allow clothing to become communications devices in their own right and allow wearers to unplug from wires and use smart textiles to gather information and then disperse that information through wireless communications. Just one application of the technology would be the remote monitoring of patients. Vital data could be captured through gowns and then beamed wirelessly to a doctor, a hospital, a family member or wherever it needed to go.
Among the first to produce commercial electronic apparel were Dutch electronics giant Phillips NV, the European division of Levi Strauss & Co. and Massimo Osti, an Italian designer. In 2000 they introduced their Industrial Clothing Design Plus (ICD+) apparel line. The line included four jacket styles, each equipped with a microphone, remote controller, mobile phone, an earphone and a MP3 player. Retailing for US$600 and up, the jackets had limited commercial success. Contributing to this lack of success was the need to remove a garment's electrical componentry before it could be washed.
Phillips NV continues to invest in the development of wearable electronics- designing working prototypes that incorporate conductive textiles, fabric switches, fabric wiring, fabric stretch sensors, high-sensitivity fabric antennas and flexible electro-luminescent displays. Phillips has also developed apparel that features embedded GPS systems, mobile phones and digital cameras.
More recently, textile research and development company Canesis, has led the field. The company - a subsidiary of Canesis Network Ltd (formerly the Wool Research Organisation of New Zealand) - pioneered the development of the Softswitch, a fabric-based switch and pressure sensing technology. Softswitch is a washable and flexible textile composite fabric that acts as a switch under finger pressure. Burton Snowboard was one of the first apparel companies to use the technology. A Burton jacket which uses a Softswitch sleeve panel to control an integrated Sony MiniDisc personal stereo was named by TIME Magazine as "one of the coolest inventions of 2002".
Canesis subsequently teamed up with Australian Wool Innovation (AWI) to develop a heating system totally comprised of textile based materials. Unlike earlier heating systems that incorporate stiff, heavy wires, the system feels and drapes like a conventional textile, and is durable and washable. The heating system is currently being incorporated into socks as well as interior products such as upholstery and blankets.
Canesis has also developed products that "light up." A variety of products including safety apparel, novelty children's wear and textile displays incorporate electro-luminescence (EL) technology. Electro-luminescent materials are flexible and completely integrated into the products. The challenge has been to lay electro-luminescent components directly onto fabrics in such a way that retains the flexibility of the underlying textile. That technology could be used to create wall coverings or drapes that illuminate interiors in new ways.
Other players in the smart textile field include the switching and sensing company Eleksen, who combine fabric structures and microchip technology in a product called ElekTex. The company's products are durable, washable, flexible and 100% fabric. The company is focussing its efforts on high volume consumer devices - current prototypes include soft keyboards for PDAs and floppy mobile phones. They also have their sights set on games controllers, automotive interiors and medical applications. UK-based Gorix specialises in products with temperature controlled systems. Their system contains a low-voltage heating source capable of maintaining constant temperature regardless of the external ambient temperature. Recreational jackets, blankets and beds for animals are just some of the company's products. Recently Gorix developed a heated diving suit which incorporates an advanced heating system. Previously, diving suits were heated by pumping hot water from a support vessel. The patented heating system is comprised of a series of heater pads powered by a stainless steel battery unobtrusively mounted on the diver's air cylinder. Other wearable electronics include clothing that monitors vulnerable individuals such as newborn babies and post-operative heart patients.
Besides the usual issues that need to be considered when developing a product using conventional textiles, a variety of additional issues have to be considered in the design and development of a product made using an electronic textile. For the textile technologist, a host of challenges arise in the weaving room. It is often necessary to cut or weld the yarns within the electrical network. This is done manually, slowing down the loom's running time. Some conductive yarns are in ribbon form. It is critical that the ribbon yarns do not twist during weaving. To avoid this weaving equipment must be modified. Smart textiles are typically made in short runs - and precision and quality are of the utmost importance.
Another challenge is powering the items made from smart fabrics. At present, conventional and rechargeable batteries are used but a number of developments are in the offing. Scientists in Germany have developed synthetic fibres that generate electricity when exposed to light. These fibres could be woven into machine-washable portable solar cells. The downside being clothes using the fibres as a power source wouldn't work in the dark. Another possible approach is to harness the power generated by walking. In 1996, a researcher in the USA wrote a paper about the potential for harvesting the energy generated by walking. By using a special "piezoelectric" shoe insert that flexes with each step, or a flywheel system connected to a small spring in the back of a shoe, five to eight watts could be recovered from each footfall, enough, the paper said, to power a small wearable computer. Sir Trevor Baylis, the British inventor best known for his wind-up-radio, developed a shoe that would charge a mobile phone battery. But before he could develop a market for the idea, the attacks on the World Trade Centre and the subsequent paranoia over security destroyed the market for such shoe-born devices.
