A low-cost, plastic-based textile from Stanford University engineers could cool the body efficiently when woven into clothing.
“If you can cool the person rather than the building where they work or live, that will save energy,” said Yi Cui, an associate professor of materials science and engineering at Stanford and of photon science at SLAC National Accelerator Laboratory.
The material cools by letting perspiration evaporate through the material, something ordinary fabrics already do. The Stanford invention, however, provides a second cooling mechanism: allowing heat that the body emits as infrared radiation to pass through the plastic textile.
“Forty to 60 percent of our body heat is dissipated as infrared radiation when we are sitting in an office,” said Shanhui Fan, a professor of electrical engineering who specializes in photonics.
To create the cooling textile, the researchers use a variant of polyethylene, the material that makes up ordinary food wrap. The polyethylene variant, commonly used in battery making, has a specific nanostructure that is opaque to visible light yet is transparent to infrared radiation, which could let body heat escape.
Using benign chemicals to modify the industrial polyethylene, the researchers enabled water vapor molecules to evaporate through nanopores in the plastic, allowing the material to breathe like a natural fiber.
To make the thin material more fabric-like, the engineers created a three-ply version: two sheets of treated polyethylene separated by a cotton mesh for strength and thickness.
A comparison showed that cotton fabric made the skin surface 3.6 °F warmer than the cooling textile. Such a difference, said the researchers, means that a person dressed in the new material might feel less inclined to turn on a fan or air conditioner.
Also: Read more Materials & Coatings tech briefs.