TECH SPECIAL
Now, a dress for all seasons
It’ll Automatically Warm You Up, Or Cool You Down
Washington:
Scientists have created a fabric that can automatically regulate
the amount of heat that passes through it, helping a person stay cool or warm depending
on the weather condition. When conditions are warm and moist, the fabric allows
heat to pass through. When it’s cool and dry, the fabric reduces the heat that
escapes, researchers said.
Researchers from University of Maryland created the fabric from
specially engineered yarn coated with a conductive metal.
This is the first textile shown to be able to regulate heat
exchange with the environment, according to the study published in ‘Science’.
Under hot, humid conditions, the strands of yarn compact and
activate the coating, which changes the way the fabric interacts with infrared
radiation. They refer to this as “gating” of infrared radiation, which acts as
a tunable blind to transmit or block heat.
“This is the first technology that allows us to dynamically gate
infrared rays,” said YuHuang Wang, a professor at Maryland.
The base yarn for this new textile is created with fibres made
of two different synthetic materials — one absorbs water and the other repels
it. The strands are coated with carbon nanotubes, a special class of
lightweight, carbonbased, conductive metal. Since materials in the fibres both
resist and absorb water, the fibres warp when exposed to humidity such as that
surrounding a sweating body.
That distortion brings the strands of yarn closer together,
which opens the pores in the fabric. This has a small cooling effect as it
allows heat to escape.
Depending on the tuning, the fabric either blocks infrared
radiation or allows it to pass through. The reaction is almost instant, so
before people realise they’re getting hot, the garment could already be cooling
them down. On the flip side, as a body cools down, the mechanism works reverse
to trap heat. “The human body is a perfect radiator. It gives off heat
quickly,” said Min Ouyang, another professor at the university.
PTI
TOI11FEB19
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