Modified silk to reflect sunlight keeps skin cooler

Approximately 15% of global electricity goes towards keeping us cool. To lessen this energy demand, scientists have been searching for passive means of cooling us that don’t require electricity.

Scientists were inspired by silk, which feels cool since it reflects a lot of the sunlight that strikes it – mainly the infrared and visible wavelengths – therefore readily radiates heat.

They engineered silk to block a lot more sunlight by embedding the fibres with Aluminium oxide nanoparticles that reflect the ultraviolet wavelengths of sunlight.

When they bathed this engineered silk in sunlight, they discovered that it stayed 3.5°C cooler than the surrounding air because of its ability to reflect most radiate and sunlight heat.

The researchers also discovered that if they draped the engineered silk over a surface made to simulate skin, it kept skin 8°C cooler under sunlight than natural silk did – also it kept skin 12.5°C cooler than cotton did. The simulated skin was manufactured from silicone rubber that has been wrapped around a heater to mimic body warmth.

Researchers made a collared long-sleeve shirt from the engineered silk and asked a volunteer to use it while standing out in sunlight on a 37°C. Infrared images revealed that the shirt stayed cool.

The engineered silk is comfortable to wear, with good breathability, and will be washed and dried without falling apart repeatedly.