Battery-powered clothes

Textiles that glow in the dark may be about to make the world a safer place for cyclists, joggers and pedestrians during bad light and at night.

Researchers at the University of Manchester in England have developed high-tech battery-powered textile yarns that can be used to make clothing glow in the dark.

The yarns have been created by the William Lee Innovation Centre (WLIC), based in the university's School of Materials, and have the potential to be incorporated into sports and general clothing.

EL yarn emits light when powered by a battery. Its development is based on thin-film electroluminescence.

The yarn consists of an inner conductive core yarn, coated with electroluminescent ink (emits light when an electric current is passed through it), and a protective transparent encapsulation, with an outer conductive yarn wrapped around it.

When the yarn is powered with an inverter, the resultant electrical field between the inner and outer conductor causes the electroluminescent coating to emit light. The emission of light occurs between the contact points between the outer yarn and the inner yarn.

Today's high-visibility products depend on external light sources for their effect. They can be ineffective in low light because they require a light source from something such as vehicle headlights to make them visible. This can lead to the wearer being seen too late.

Other potential applications for the yarn include flexible woven or knitted road safety signs that communicate written instructions.

"At the moment, the EL yarn we have developed is less flexible than conventional yarns. But it is more flexible than optical fibres that are incorporated within fabrics to provide illumination. EL yarn can be easily incorporated into a knitted or woven fabric and the resultant active illuminating fabric provides illumination when it is powered," Dr Tilak Dias, the head of the WLIC, said.

"The luminance of a single strand of the EL yarn is greater than that of photoluminescent glow yarns which are currently used in some high-visibility applications. Weaving or knitting the yarn in a particular manner, so that more yarn per unit area is achieved, improves the luminance of the EL yarn."