Nano-gold coating prevents glasses from fogging


According to a report on the website of the British newspaper The Times on December 12, eyeglass wearers can avoid the problem of glasses fogging up on cold days thanks to a gold "nano-coating" that can heat up the lenses of the glasses. .

The report says that this technology is based on an ultra-thin layer of gold particles that is applied to the lenses of glasses. This transparent coating converts sunlight into heat, which in turn prevents moisture build-up on the lenses.

Moisture in moist air cools quickly when it hits the cold glass surface, fogging up. Tiny water droplets or condensation has formed on the lens.

Tiny water droplets scatter light in multiple directions, making it hard to see things in front of you. Roughly by the same principle, fog affects vision.

According to an article published in the British journal Nature Nanotechnology, the new coating uses solar energy to raise the temperature of the lens and prevent water vapor from condensing, which prevents fogging, at least during the day. The electric heating element for anti-fogging of the rear window of the car also works according to this principle.

The new coating works because it selectively absorbs only a fraction of the energy given off by the sun. Half of the solar energy is in the infrared spectrum, and the other half is in the visible and ultraviolet radiation spectrum.

"Our coating absorbs most of the infrared radiation, which raises its temperature by as much as 8 degrees Celsius," says Ivan Ashley of ETH Zurich.

However, it absorbs only a small fraction of the visible radiation. This means that visible light passes through the coating, giving it a transparent effect.

Normally, dark surfaces absorb light and convert it into heat. The researchers were able to develop a transparent surface that also converts light into heat.

Gold is very expensive, but Ashley and his colleagues say very little gold is needed to cover it, which keeps costs down. Coatings can be obtained by conventional methods. Between two ultra-thin layers of titanium dioxide are tiny clusters of gold.

Nano-gold coating prevents glasses from fogging

Two outer layers of titanium dioxide enhance the heating effect. The entire "sandwich" is only 10 nanometers thick. For comparison, a layer of gold leaf is about 12 times thicker. The technology could also be used in car windshields, ski goggles and diving masks, the researchers said.

Source: reference news network