Tiny Clothing Wires to Ward Off the Big Chill

[Buster's Uncle]

Tiny Clothing Wires to Ward Off the Big Chill
Nanotechnology specialists promise clothing that keeps more heat in
The Wall Street Journal
By Daniel Akst  Jan. 9, 2015 11:58 a.m. ET



The problem with regular clothing is that, while it does a decent job of curtailing heat loss through contact or air, it’s terrible at capturing the radiant body heat that humans emit. Getty Images



As this week’s cold spell in much of the U.S. reminded us, clothing is supposed to keep you warm. But scientists at Stanford University say it could be doing a much better job—so much better, in fact, that it could put a serious dent in global energy consumption.

That’s the concept behind a high-tech fabric the researchers have developed. By coating textiles with a network of tiny, invisible metallic wires—a network that won’t be felt by wearers—the scientists discovered that they could boost a garment’s thermal properties without sacrificing functionality.

The problem with regular clothing is that, while it does a decent job of curtailing heat loss through contact or air, it’s terrible at capturing the radiant body heat that humans emit. A Mylar overcoat would contain this heat (it’s actually a form of electromagnetic energy), but it would make the wearer uncomfortable because the material doesn’t breathe. As the scientists explain in a new paper on the subject, “the plastic sheet and the aluminum film [in a Mylar coat] are not vapor permeable.”

Enter nanotechnology, the science of very small things. Nanotech fabric coatings are already being used to make garments shed water, kill microbes and block sunlight. The Stanford scientists found that by coating fabric with silver nanowires in a chemical bath, they could produce clothing that traps the body’s radiant heat but still breathes about as well as uncoated fabric and can be washed freely.

The material can even provide further warmth through the application of a little electricity. Imagine a sweater that comes with a charger like the one you use for your smartphone. You could even carry a battery in your pocket on the ski slopes.

So far the scientists have used the technology on cotton and synthetic fabrics, but Yi Cui, one of the paper’s authors, says that he’s convinced it will work on any textile. He adds that very few of the nanowires would come off. The wires would impart a silvery gray sheen to a fabric, but this could be masked by dyes.

How much warmer can such fabrics make you? Dr. Cui figures that clothing coated in nanowires might enable normally attired wearers to remain comfortable at indoor temperatures of 60 or even 55 degrees Fahrenheit during winter, without any added electricity. That may not sound like much, but the scientists point out that indoor heating accounts for nearly half of global energy consumption.

They have calculated that one person wearing their thermal textiles—with 12 watts added to warm things further—could save about 1,000 kilowatt-hours of electricity a year, or about what an average home uses in a month. The garments would be useless in summer, but the scientists are working on fabrics that can do the same thing in reverse, helping wearers to shed radiant body heat.

Dr. Cui, a professor of materials science and engineering, estimates that covering an entire human body would only take perhaps 50 cents worth of silver. He adds: “It’s going to be a lot cheaper than cashmere, for sure.”


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