A team of researchers at the Swiss Federal Institute of Technology (ETH Zurich) have developed a gold nano coating that keeps glasses fog-free in humid conditions.
According to Interesting Engineering, the researchers have recently filed a patent for an ultra-thin transparent coating that removes existing fog on the eyeglasses and prevents formation of fog.
Researchers Detail How This Anti-Fog Technology Works
The Zurich researchers developed a special coating that uses titanium oxide and gold particles that selectively absorbs infrared radiation from the sunlight, creating a heating effect to keep the fog away.
The coating relies on renewable sources to heat up by up to 46F, which is unlike other technology that relies on water and hydrophilic molecules to prevent fogging.
However, it is important to note that the gold coating does not absorb the remaining half of the sunlight that consists of UV rays and visible light.
"We achieve this heating effect by fabricating a metal layer (gold) at a very specific thickness (called the percolation threshold), where an optical anomaly occurs," Iwan Haechler, ETH Zurich Ph.D. student says.
He adds that this effect leads to a strong and broadband near-infrared absorption of just over a few nm, which is about 10 nm in total.
Engadget writes that the 10 nm thick coating has gold between layers of titanium oxide that protect the gold against wear.
This design reportedly also prevents overheating in warm weather since it prevents radiation from penetrating to the other side.
The gold part of the eyewear is 12 times thinner than a regular gold leaf sheet, and because of this, it can be easily integrated under existing standard coatings.
The gold nano coating also protects the eyeglasses from outdoor influences such as scratches, dirt, or chemicals, which also makes it flexible and not easy to break.
According to Haechler, the researchers at ETH Zurich were motivated to show the potential of solar energy by applying physical concepts and rational engineering for heating.
Starting from eyewear, the researchers are hoping that this gold nano coating technology can be helpful in developing ideas that can reduce electricity consumption especially in vehicles.
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The Gold Nano Coat Is Not As Expensive As Expected
While gold is quite expensive as it is, researchers say that the amount of the material needed to make the nano coating is so little that the price of the glasses will not go up that much.
According to Interesting Engineering, Haechler explained that the gold layer is only 5 nm thin, which only requires as much as 100 mg or gold per square meter of material.
Assuming that a pair of glasses is around 2x15 squared cm2, it would mean that it would only use approximately 0.3 mg of gold, which is only around $0.017.
However, there is a limitation to this product as it does rely on a certain amount of light although it can work at extremely low levels of solar radiation.
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