Chinese researchers have announced that they have created a “smart” innovative fabric that reflects away heat and can reduce body temperature by almost five degrees Celsius. The so-called “meta-fabric”, which looks like a simple T-shirt, could, if mass-produced, help people protect themselves from the increasing heat caused by climate change.
To reduce the absorption of solar radiation, clothing designers usually use light colours in fabrics. Another method is to reflect solar electromagnetic radiation, both ultraviolet (UV) and near-infrared (NIR). The latter heats the objects that absorb it and then they slowly cool down as they gradually emit it back into the environment. One disadvantage is that after being emitted by an object, near-infrared radiation is often absorbed by water molecules in the atmosphere, which heats up the surrounding air.
A better solution is radiation in the mid-infrared spectrum (MIR), which has a longer wavelength and is not absorbed by the molecules in the surrounding air, but goes directly into space, cooling both the objects themselves and the air around them. Human skin, unlike clothing, emits MIR.
The Chinese researchers from the Huachong University of Science and Technology, who published the paper in the journal “Science”, according to the same and “New Scientist”, designed the first fabric that allows in mid-infrared MIR radiation, which is emitted from the skin, to easily penetrate the garment. To be truly effective, the new fabric must be in contact with the skin.
The meta-fabric, which can be dyed in various colours and is made of polylactic acid, synthetic Teflon fibres and titanium dioxide nanoparticles (also present in sunscreens), also reflects ultraviolet, visible and near-infrared radiation into space, which allows for a greater reduction in body temperature.
Experiments have shown that when with a normal cotton garment the skin temperature is around 37 degrees, with the new fabric it drops to 31 to 32. In another experiment with cars, one of which was covered with the meta-fabric, a second with a standard cover and a third left uncovered under the sun at noon, the temperature was 60 degrees Celsius in the latter, 57 degrees in the latter, and only 30 degrees in the former.
Although it looks like a normal garment, it is actually a kind of mirror, according to the Chinese researchers, who are already looking for textile and clothing manufacturers to commercialise their invention. They estimate that the new technology only increases production costs by 10%.
