Soon, clothes that generate power from body's motion

Lightweight, comfortable clothes that can generate power using body movements may soon become a reality, thanks to a new coating developed by scientists that turns fabrics into circuits.
Scientists at the University of Massachusetts Amherst in the US have invented a way to apply breathable, pliable, metal-free electrodes to fabric and off-the-shelf clothing so it feels good to the touch and also transports enough electricity to power small electronics.
"Such conducting textiles can be built up into sophisticated electronics. One such application is to harvest body motion energy and convert it into electricity in such a way that every time you move, it generates power," said Trisha Andrew from University of Massachusetts Amherst.

Powering advanced fabrics that can monitor health data remotely are important to the military and increasingly valued by the health care industry, Andrew said.
Generating small electric currents through relative movement of layers is called triboelectric charging.
Materials can become electrically charged as they create friction by moving against a different material, like rubbing a comb on a sweater.

"By sandwiching layers of differently materials between two conducting electrodes, a few micro-watts of power can be generated when we move," Andrew said.
The study published in the journal Advanced Functional Materials describes the vapour deposition method they use to coat fabrics with a conducting polymer, poly(3,4- ethylenedioxytiophene) also known as PEDOT, to make plain- woven, conducting fabrics that are resistant to stretching and wear and remain stable after washing and ironing.

The thickest coating they put down is about 500 nanometres, or about 1/10 the diameter of a human hair, which retains a fabric's hand feel.
The researchers tested electrical conductivity, fabric stability, chemical and mechanical stability of PEDOT films and textile parameter effects on conductivity for 14 fabrics, including five cottons with different weaves, linen and silk from a craft store.
"Our article describes the materials science needed to make these robust conductors. We show them to be stable to washing, rubbing, human sweat and a lot of wear and tear," said Andrew.
PEDOT coating did not change the feel of any fabric as determined by touch with bare hands before and after coating.

The researchers said their invention overcomes the obstacle of power-generating electronics mounted on plastic or cladded, veneer-like fibres that make garments heavier and/or less flexible than off-the-shelf clothing "no matter how thin or flexible these device arrays are."
"There is strong motivation to use something that is already familiar, such as cotton/silk thread, fabrics and clothes, and imperceptibly adapting it to a new technological application," Andrew said.
"This is a huge leap for consumer products, if you don't have to convince people to wear something different than what they are already wearing," she said.