The fabric has been developed by Professor Yi Cui, who is a materials scientist based at Stanford University in Palo Alto, California. The fabric is transparent to body heat, and this p allows energy to radiate away.
The basis of the fabric’s properties is infrared radiation, according to The Verge. The use of this low wavelength radiation allows the fabric to block visible light, but it also allow body heat to leave the body.
The fabric is based on the observed properties of a common, and inexpensive, plastic – polyethylene. The version of the plastic used has many nanopores (tiny fused bubbles, just a billionth of a meter in diameter) within its structure. These nanopores are interconnected and allow fluids (such as air) flow from one side to another. Based on these factors, the new material is described as “nanoporous polyethylene.”
Through various experiments, the researchers developed the material to contain nanopores of a specific size, at between 50 and 1,000 nanometers. This size allows the nanospores to scatter and block visible light but not infrared wavelengths (wavelengths above 2,000), which instead can pass through the fabric. In trials the fabric allowed over 90 percent of the infrared to pass through. Given that infrared is, in effect, ‘heat’ this means that the fabric, unlike conventional clothing, does not retain heat. The process overall is referred to as “effective radiative cooling.”
To test this, studies showed that when a person wears a cotton shirt their skin temperature increases by 3.5° Celsius (6.3° Fahrenheit) (that is compared to wearing no shirt at all.) However, with the new fabric, skin would rise by only 0.8 °C (about 1.4 °F).
This remains theoretical at the moment. The new fabric has, so far, only been tested in the laboratory and has yet to be made in large quantities. On a commercial scale, the fabric should have sufficient air permeability, water-wicking rate, and mechanical strength for wearability.
The new fabric has been described in the journal Science. The research paper is titled “Radiative body heat cooling by nanoporous polyethylene textile.”
