Chinese Researchers From Wuhan Reach Out To Fabric Producers With Their Ground-Breaking Metafabric Which Can Cool The Wearer By Up To 5°Celsius

Image Courtesy of H.U.S.T.

While it’s easy to engineer clothing that keeps you warm, it’s far harder to come up with an outfit that can keep you cool on a scorching summer day.

Now, researchers have designed a fabric that looks like an everyday T-shirt, but can cool the body by nearly 5°C.

They say the technology, if mass produced, could help people around the world protect themselves against rising temperatures caused by climate change.

Guangming Tao at Huazhong University of Science and Technology in Wuhan, China, and his colleagues developed what they call a “metafabric” by combining microscopic beads and fibres of titanium oxide, Teflon and a plastic called polylactic acid, all embedded within larger fibres.

The fabric consists of polylactide with titanium dioxide nanoparticles sewn into its fibres.

The finished material thickness is 0.55 mm.

The project is a collaboration between researchers from the Huazhong University of Science and Technology, Wuhan Textile University, the Intelligent Wearable Engineering Research Centre of Qingdao and the China Textile Academy in Beijing.

Clothing to beat the heat usually means light-coloured fabric to reflect visible light, or fabric that reflects other electromagnetic radiation from the sun like ultraviolet (UV) and near-infrared radiation (NIR).

When the 550-micrometre metafabric comes into close contact with skin, it uses chemical bonds to absorb body heat and re-emit its energy into space as MIR.

It has been engineered to reflect both UV and NIR. Titanium dioxide powder, a substance also found in sunscreen, was added to the fabric’s polymer fibres to make them reflective, and it has polylactic acid to allow the material to emit MIR.

The scientists said the fabric was created using a weaving technique that allows air to circulate, and they estimate it would cost 10 per cent more to manufacture than traditional cotton – they are reportedly looking into mass production of the fabric.

When emitted from an object, NIR is often absorbed by nearby water molecules, heating up the surrounding air, which makes it less effective at cooling.

But MIR can cool off both an object and its surroundings as the energy goes directly into space.

The beads of titanium oxide – a substance also found in sunscreens – and the Teflon reflect ultraviolet and visible light, while the polylactic acid fibres emit infrared light. The sizes of the particles are designed to optimise these properties.

“Through structural control, our metafabric achieves a nearly perfect mid-infrared emissivity, thereby maximising heat dissipation,” says Tao.

In one test, a volunteer wearing a vest made half of the metafabric and half of cotton sat in direct sunlight for an hour. The skin temperature under the metafabric rose from around 31°C to 32°C over that time, while the skin temperature under the cotton rose to around 37°C.

In another test, one car was covered with the metafabric, another with a shop-bought cover and a third was left uncovered. When left in the sun from 11am to 1pm, the temperature rose to 60°C in the uncovered car, 57°C in the car with the standard cover and 30°C in the one with the metafabric cover over that period.

The metafabric is most effective when in contact with the skin. If someone wore a garment made of the metafabric over a thick layer of normal clothing, much of the cooling effect would be lost because less body heat would be conducted to the metafabric and then radiated away.

“This technology can be seamlessly connected with mature, modern manufacturing,” says Tao. Some well-known clothing brands are interested in the metafabric, he says. “We hope that our products will be available in a year or so.”

“This work is absolutely impressive based on its outdoor cooling performance,” says Po-Chun Hsu at Duke University in North Carolina.

Ma and Tao are now reaching out to textile manufacturers and clothing companies to try to get their fabric on shelves.

They say the nanomaterial-infused fabric should add only about 10% to typical clothing manufacturing costs. “We can make it with mass production, which means everybody can get a T-shirt … and the cost is basically the same as their old stuff,” Ma says. “It can benefit everybody.”