Researchers develop nano-thin gold coating to prevent glass from fogging up

Shawn Knight

Posts: 14,673   +175
Staff member
In a nutshell: Researchers at ETH Zurich have spent the last few years perfecting a coating capable of passively preventing fogging on glass surfaces. Their latest iteration consists of extremely thin clusters of gold situated between ultrathin layers of titanium oxide on the top and bottom. The resulting coating is able to absorb a portion of infrared radiation from the Sun, which heats up the surface by as much as eight degrees Celsius and prevents condensation from forming.

It's similar to how the anti-fog system on a car's rear window works, but without the use of electric heating via wires.

The team published their first research paper on the topic back in 2019. Their revised coating is significantly thinner than what they previously shared, making it more transparent. It is also bendable, enhancing its versatility.

Gold is an expensive material but so little of it is needed for the coating that it won't make application cost-prohibitive. According to the team, the tri-layer coating measures just 10 nanometers thick. For comparison, a typical gold leaf or foil is about 12 times thicker. The coating is fabricated using chemical vapor deposition in a cleanroom.

The gold clusters in the middle of the titanium oxide sandwich do touch each other, but only minimally. That means that in the absence of sunlight, electricity could be used to heat the coating if needed. Titanium oxide acts as an insulating material, and the top layer protects the gold clusters from wear.

Obvious applications include eyewear and automotive windshields, but alternative use cases could include things like windows, mirrors and optical sensors. Notably, while the coated surface will heat up, the material prevents radiation from reaching the inside (of a car or building, for example) so they'd heat up even less than they would without the coating.

ETH Zurich has applied for a patent on the material. Additional experiments will help the researchers determine if other metals can perform equally as well or better than gold. Their latest findings have been published in the journal Nature Nanotechnology.

Image credit: Jamie Street

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Posts: 6,527   +7,473
so little of it is needed for the coating that it won't make application cost-prohibitive
Marketing will make it that way, advertising as gold-coated, and charging 10 times over the cost.

You'll see.


Posts: 2,192   +882
Trying to film during COVID was a ****ing pain for us glasses wearers. Yes, yes, it's called contact lenses :X


Posts: 117   +139
Would be nice to have as a glasses wearer, but seems like it definitely would need to use something else than gold to not cost a bomb


Posts: 1,490   +1,080
Would be nice to have as a glasses wearer, but seems like it definitely would need to use something else than gold to not cost a bomb

Probably only a few cents of gold - The mass of 1000 gold leaves is about 20 grams. that can cover 7Metres squared: 0.2/7/12 times 20 grams


Posts: 107   +118
I'm a SCUBA diver so it would be awesome if this worked on diving masks. The spit or liquid soap methods to keep dive masks from fogging over leaves a lot to be desired.


Posts: 311   +298
For anti-fog coatings in spray forms have been available for at least a decade now all over the world. These can be applied to virtually any solid surface (but preferable to mirrors and windshield), and will prevent them from fogging up - without any gold or having to apply a gold layer in industrial production. So, I can't fathom what's newsworthy about this, as the technology is absolutely not new or novel.

The other thing is: all these anti-fog technologies have their limitation The real problem with them is, than even though they prevent the surface from fogging up, but they do this by making the surface hydrophilic (meaning it will cling to water). So, instead of tiny droplets that make the surface "fog up", the surface of things will now be fully covered in a thin layer of water. Which is preferable in some circumstances... but that layer of water will catch and kinds of dust and deposit it on the surface. This in turn makes the anti-fog layer ineffective, because water will now be able to form droplet on the small particles of dust, fogging up the surface, nulling the effect of the anti-fog coating.

This will obviously be the same also for this kind of coating.


Posts: 1,288   +1,295
My wife's eyeglasses get foggy when there's a change in temperature from cold to hot, and when being in a cold place and wearing mask. This will be useful for her.


Posts: 580   +396
I'm pretty sure there's a ceramic or plastic coating that does the same or even better, but you can rip off the customers much more if you say "gold" or "platinum". As if glasses aren't already 20x overpriced.

Those people remind me of one species from Star Trek that was incredibly greedy, and would sell their own children for a few grams of "Latinum".