Scientists at ETH Zurich have developed a special coating that prevents the lenses of eyeglass lenses from fogging up. Apparently not all heroes wear a cape.

This has been a problem since the advent of optical lenses, but it’s fair to say it peaked during the pandemic when anyone wearing glasses found out the hard way that most face masks blow your breath into your eyes. You’d think someone would have solved this by now, but it’s harder than you’d think.

The difficulty of the problem is evidenced by the lack of up-to-date solutions. You can wipe your glasses if they fog up or…well, that’s about it. There are anti-fog sprays and special lens coatings that help, but they only minimize the problem.

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You don’t have to be a physicist to understand that heat is the best solution. Glasses fog up when hot vapor comes into contact with their cooler lenses. These temperature fluctuations turn the vapor into moisture and your glasses will fog up because they are wet.

Unfortunately, warming glasses is not an easy task. Traditional methods would require you to find a transparent material that can be heated externally, develop a power source for the material, and make sure the lenses or frames don’t overheat. That’s a pretty tall order, especially when you consider that any added bulk or weight will add to the wearer’s discomfort.

The ETH Zurich team has worked around these technical issues by choose a different approach. They developed a special gold coating that uses solar energy to produce heat. It does not require a battery or wires or components other than the coating itself.

The way it works is to place tiny clusters of gold between ultra-thin layers of titanium oxide. Gold is a fantastic conductor of heat, and the titanium oxide layers enhance the retention of the metal just enough to make it perfect for heating glass and similar surfaces.

The whole thing is just 10 nanometers thick (the processing size for some microchips) and can be used with other coatings – so it should work with transition lenses and for use in car windows, for example. In fact, the scientists are determined to test the coating on other surfaces, such as windows and mirrors.

It will also be interesting to see how this coating can be applied to other optics, such as sensors and lasers. The uses for this coating could be endless, especially as the scientists insist it’s not as expensive as one might think due to the incredibly small amount of gold required to make the coating.

It is unclear exactly how much heat can be generated with this technique, but say the researchers it can heat the surface up to 8 degrees Celsius. That’s certainly enough to prevent vapor from fogging up your lenses under normal circumstances. But it is not enough to produce electricity in usable quantity.

This probably won’t solve the world’s energy crisis, but it certainly has the potential to make life easier for the billions of spectacle wearers.