메시지

A new route to self-heating clothing

While delivering sufficient energy to bond the silver wires to the cloth fibres, the underlying polymer is not damaged.

“When compared with the current state of the art in thermal patches, the creation generates more heat per patch area and is more durable after bending, washing and exposure to humidity and high temperature,” claims Rutgers.

The silver is applied to finished polyester cloth by dipping it into a silver-containing solution and drying. The combination is then pulsed with light from a high-power xenon source.

The resulting cloth can be powered with a volt or so, but is prone to damage when driven much over its working voltage.

Comparing silver-coated cloth with and without the photo-thermal treatment, the treated cloth has better electrical conductivity and was significantly more durable against humidity, repeated bending or washing.

Rutgers University worked with Oregon State University on this project, which is described in ‘Rapid Pulsed Light Sintering of Silver Nanowires on Woven Polyester for personal thermal management with enhanced performance, durability and cost-effectiveness‘, published in Nature Scientific Reports.

Loosely, both treated and untreated cloths gain resistance during the first few bending cycles, and then plateaued – with the treated cloth behaving better.

The same is true or repeated washing cycles except, instead of plateauing, there was slow but steady decline.

Humidity was a mixed story, with the treated cloth always better. At 25°C deterioration plateaued, while at 70°C there was steady decline.

Diagram: Most of it is self-explanitory. The blue quadrant is the calculated temperature contours (°C) at end of a light pulse for a bare single fibre – the profile for fibre plus nanowires was not provided in a form Electronics Weekly can publish, but is in the paper (Fig 7d) in which the fibre stays below 40°C but the nanowires reach 140°C.