INTRODUCTION

Smart fabrics and intelligent textiles – material that incorporates cunning molecules or clever electronics – is thriving and European research efforts are tackling some of the sector’s toughest challenges.

Clothes that monitor your heart, measure the chemical composition of your body fluids or keep track of you and your local environment promise to revolutionise healthcare and emergency response, but they present tough research challenges, too.

Smart textiles must be comfortable, their technology must be unobtrusive, they must withstand a difficult and variable environment and, particularly for medical and emergency applications, they must be absolutely reliable.

These are all tough challenges, but they must be overcome to realise the considerable benefits and lucrative market potential of smart textiles and intelligent fabrics (SFIT). The market is thought to be worth over €300m and current growth rates are about 20% a year.

Fashion 2.0

Europe has not been slow to spot the potential of Fashion 2.0, with many projects funded by the EU to develop new applications and innovative solutions to old problems. The EU has even set up a research cluster for the sector.

“We formed the SFIT cluster because there are many European projects researching new types of smart fabric,” explains Jean Luprano, coordinator of the SFIT Cluster. “We wanted to share expertise and find a way to avoid reinventing the wheel. Often the work of one project could help another, even if they were not working on the same area.”

“Many of the underlying objectives are the same, like connectivity, wearability and ensuring the fabric is accepted by users.”

The cluster achieved some remarkable cross-pollination between projects. “The textile electrode used in Wealthy, for example, extended to three other projects, MyHeart, Proetex and Biotex. In Biotex for instance, it was not our intention to develop a dry textile electrode again, so the help was a bonus.”

The SFIT Cluster currently regroups the projects Context, Proetex, Sweet, Stella, Ofseth, Biotex and Clevertex. Lessons were taken from Wealthy, which had finished its work developing intelligent systems for health monitoring before the cluster started, and from MyHeart (see our feature article), which developed a textile sensor for continuous heart monitoring.

DisasterWear, clothing for emergencies

SFIT’s Context (see related articles) project sought to develop contactless sensors for the prevention of lower back pain and repetitive strain syndrome.

Proetex (see related articles) aimed its sights at rescue workers like fire fighters and is developing a system to monitor the wearer and the outside environment.

Sweet project is developing stretchable and washable electronics for embedding in textiles so smart clothes can cope with daily wash, wear and tear.

The Stella project is developing stretchable electronics for large area applications. Currently, there are no stretchable electronics on the market but they could have wide application, particularly for health monitoring. The team hopes to develop conducting substrates within the very weave of fabric, which will allow sensors to move with the body.

Optical fibres also offer a promising avenue for new smart clothing because of their potential flexibility and their capacity to use light both as an information carrier and a sensor in itself. The team behind the Ofseth project (see our feature article) is aiming at applications in oximetry – a clever non-invasive way to measure the oxygen content of blood

In a hospital setting, a clip is attached to a patient’s finger measuring a ratio in the absorption of red and infrared light passed through a patient’s finger, which varies depending on the state of oxygen-rich, bright red blood and oxygen-poor, dark red blood. Ofseth researchers hope to replicate the measure in clothing (without the need for the finger clip typically used in hospitals) by placing optical fibres around the neck of a smart garment.

In a related healthcare activity, the Mermoth project worked on integrating smart sensors, advanced signal processing techniques and new telecommunication systems on a textile platform.

Wet electronics

Biotex project (see our feature article) is looking at the chemical monitoring of textiles, a new frontier in the emerging field of smart textiles. Most smart fabric applications want to stay dry, but Biotex is hoping to develop sensors that can measure body fluids like sweat, too. If they are successful, it will open up whole new areas for smart applications.

“Right now we’re looking at sporting applications, because the medical applications are very difficult to bring to market and require enormous validation efforts to ensure reliability in a medical setting,” explains Luprano.

The Biotex system aims to measure the conductivity, electrolyte level, temperature and pH of the users sweat, all enormously useful indicators for sporting applications. The project also aims at monitoring wound healing by placing biosensors in contact with exudates present in wounds.

Clevertex is taking a big picture view of the field in its efforts to develop a strategic ‘master plan’ for transforming, by 2015, the traditional textile and clothing sector into a knowledge-driven industrial sector.

The projects in the SFIT cluster mean a double benefit for Europe’s smart-clothing sector. The applications are useful in themselves, and the technical solutions developed in each project will benefit the range of smart-clothing systems.

Smart material

Smart materials are materials that have one or more properties that can be significantly changed in a controlled fashion by external stimuli, such as stress, temperature, moisture, pH, electric or magnetic fields.

There are a number of types of smart material, some of which are already common. Some examples are as following:

• Piezoelectric materials are materials that produce a voltage when stress is applied. Since this effect also applies in the reverse manner, a voltage across the sample will produce stress within the sample. Suitably designed structures made from these materials can therefore be made that bend, expand or contract when a voltage is applied.
• Shape memory alloys and shape memory polymers are Thermoresponsive materials where deformation can be induced and recovered through temperature changes.
• Magnetic shape memory alloys are materials that change their shape in response to a significant change in the magnetic field.
• pH-sensitive polymers are materials which swell/collapse when the pH of the surrounding media changes.
• Temperature-responsive polymers are materials which undergo changes upon temperature.
• Halochromic materials are commonly materials that change their colour as a result of changing acidity. One suggested application is for paints that can change colour to indicate corrosion in the metal underneath them.
• Chromogenic systems change colour in response to electrical, optical or thermal changes. These include electrochromic materials, which change their colour or opacity on the application of a voltage (e.g. liquid crystal displays), thermochromic materials change in color depending on their temperature, and photochromic materials, which change colour in response to light – for example, light sensitive sunglasses that darken when exposed to bright sunlight.
• Non-Newtonian fluid is a liquid which changes its viscosity in response to an applied shear rate. In other words the liquid will change its viscosity in response to some sort of force or pressure. One good example of this is Oobleck, a fluid that seems to temporarily turn into a solid when a force is applied quickly.^[1] Another good example is Custard, as long as it is starch based.