The opposite effect occurs in cool conditions, when the textile is cold or dry: the fibers expand, reducing gaps to prevent heat from escaping. For example, when conditions are warm and moist, such as those of a sweating body on a summer day, the fabric allows infrared radiation (radiant heat) to pass through. In cooler and drier conditions, the fabric reduces the heat that escapes.
The base yarn is developed using fiber which is made of two different synthetic materials.
The fabric is made from a particularly engineered thread, covered with conductive coating metal.
Scientists have said that the new fabric needs more work before it is commercially exploited, but all of its materials are already available on the market, and even its production will not face technical difficulties.
The strands are coated with carbon nanotubes, a special class of lightweight conductive metal. This material in the fabric both absorb and resist the water.
Previously, researchers demonstrated fabrics that can increase porosity in response to sweat or temperature, as well as textiles that transmit infrared radiation from the human body. When the fibers come together, the electromagnetic coupling of the carbon nanotubes also changes.
This is the first technology that allows us to dynamically gate [regulate] infrared radiation, said YuHuang Wang, a UMD professor of chemistry and biochemistry and one of the papers corresponding authors. "It gives off heat quickly", said co-lead author Professor Min Ouyang, a researcher at the University of Maryland. When the fibers are brought closer together, the radiation they interact with changes.
Depending on the tuning, the fabric either blocks infrared radiation or allows it to pass through. The reaction is nearly instant, so before people realize theyre getting hot, the garment could already be cooling them down. However, the moment body gets cooler, the gating mechanism starts working in reverse to allow the heat. The journal Science published this discovery in their 8 Feb' 2019 issue.
"This pioneering work provides an exciting new switchable characteristic for comfort-adjusting clothing", said Ray Baughman, a professor of chemistry at the University of Texas who was not involved in the study.
"If you're hot and sweating, this textile will respond... However, no one before had found a way to switch both the porosity and infrared transparency of a textile so as to provide increased comfort in response to environmental conditions".
Scientists are further planning to modify it more before it comes to market.
This work was supported by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, as part of its "Delivering Efficient Local Thermal Amenities (DELTA)" program (Award No. DE-AR0000527).