Scientists at Stanford University have developed a new type of textile that reportedly cools your body, thus reducing the need for energy-intensive air conditioning. Recently published in the Science journal, the research could pave the way for a new family of smart fabrics that can handle body heat more efficiently than currently-available natural and synthetic textile. Speaking about the breakthrough, Yi Cui, a professor of photon science and materials engineering at the university, said:
If you can cool the person rather than the building where they work or live, that will save energy.
Compared to ordinary cotton garments, the plastic-based textile helps lower temperatures by nearly 4 degrees Fahrenheit. Fashioned out of polyethylene, the new smart fabric is capable of discharging the wearer’s body heat in two different ways: cooling caused by evaporation of perspiration as well as allowing the infrared radiation emanating from the body to escape through the fabric.
As pointed out by the scientists, human bodies are known to emit heat as infrared radiation that, although invisible to the naked eye, can be detected in the dark using night-vision goggles. Woolen clothes and blankets tend to trap these infrared emissions, thereby keeping us warm during cold weather. Shanhui Fan, a photonics expert and a professor of electrical engineering, added:
Forty to 60 percent of our body heat is dissipated as infrared radiation when we are sitting in an office. But until now there has been little or no research on designing the thermal radiation characteristics of textiles.
For the research, the team relies on techniques from nanotechnology, chemistry and photonics to turn polyethylene, a transparent plastic that is widely used as kitchen wrap, into an innovative cooling textile that can be woven into a variety of clothing. The new material, which is opaque to visible light, allows the passage of air, thermal radiation and even water vapor.
As explained by the group, polyethylene-based wraps are known to allow infrared radiations to travel through them. They are, however, completely transparent and also impervious to water. To make it better suited for use as clothing, the substance was made to undergo a number of highly-specialized chemical treatments.
To that end, the researchers chose a form of polyethylene that is widely used for making batteries. Given its particular nanostructure, this material is opaque under visible light, but turns transparent upon exposure to infrared radiation, allowing it to escape without difficulty. The plastic, the team stated, was used as the base material for the cooling textile.
Following this, the scientists treated the industrial polyethylene with an assortment of chemicals, in order to make it permeable to water vapor molecules. This, according to research student Po-Chun Hsu, ensured that the single-sheet material can breathe much like natural fiber. To turn it into something more wearable, the team came up with a thicker, three-ply version, featuring two sheets of the cooling textile with a cotton mesh in between.
To test its efficacy, a tiny piece of the smart fabric, along with a cotton cloth of similar size and thickness, was placed on a surface about as warm as the human skin. The amount of heat trapped by each of these fabrics was then calculated. Talking about the tests, Fan said:
Wearing anything traps some heat and makes the skin warmer. If dissipating thermal radiation were our only concern, then it would be best to wear nothing.
During laboratory testing, the cotton textile was make the body surface warmer by 3.6 degrees Fahrenheit than the smart fabric. The breakthrough, the scientists believe, could help reduce our dependency of energy-guzzling air conditioning. At present, the team is trying to make the material more customizable, by adding more textures, colors as well as other garment-like features. The researchers added:
In hindsight, some of what we’ve done looks very simple, but it’s because few have really been looking at engineering the radiation characteristics of textiles.
Source: Stanford University