Video: Search for an ideal anti-fog coating “heats” up the competition | The American Ceramic Society

Video: Search for an ideal anti-fog coating “heats” up the competition

03-20 Anti-fog coating

[Image above] Researchers at ETH Zurich developed an anti-fog coating that uses heat to defog surfaces. Shining a light through a pane coated with the material prevents the lit area from fogging. Credit: Christopher Walker, ETH Zurich

There are a few reasons I prefer winter over summer, the biggest being there are no mosquitoes trying to steal my blood. Yet overall I find more perks to summer, one of which is shared by anyone who wears glasses—summer means no foggy lenses when entering a warm building after being outside.

While some of us simply deal with this nuisance, others shell out a regular allowance for one of numerous anti-fog sprays on the market. These sprays coat the glass in a hydrophilic (water-attracting) solution that causes water to condense into a thin film of liquid rather than remaining as separate droplets, making it easier to see through the glass. But though these sprays provide temporary fog relief, none last indefinitely because the film dries up or becomes unevenly distributed over time.

Besides hydrophilic anti-fog methods, heat is another way to keep condensation from fogging up glass. This method is commonly seen in vehicles, where a fan blows warm air across the front windshield and electrical heating elements warm the rear window. Yet heating requires an electrical energy source to run the fan and heating elements, so it is not a convenient method for eyeglasses.

Could we take the best of both methods and create an easy-to-apply, long-lasting coating that heats glass without needing batteries? Based on today’s video, it appears ETH Zurich researchers found a way to do so—through passive heating.

No more daily applications of anti-fog spray when you use the new coating from ETH Zurich! Credit: ETH Zürich, YouTube

Instead of producing heat from an electrical energy source, ETH Zurich researchers created a transparent coating that heats glass with sunlight. “Our coating absorbs the infrared component of sunlight along with a small part of the visible sunlight and converts the light into heat,” explains Christopher Walker, a doctoral student at ETH Zurich, in an ETH Zurich press release. Walker is lead author on a recent study by ETH Zurich researchers describing their new anti-fog coating.

When the researchers tested their coating—a few nanometers-thick material of gold nanoparticles and titanium oxide—against traditional anti-fog agents, fogged surfaces cleared four times faster when coated with their material.

But the coating is special for more than just fast defog time—it is also special for its transparency. “Normally, it’s dark surfaces that absorb light and convert it into heat,” says Efstratios Mitridis, another doctoral student, “but we’ve created a transparent surface that has the same effect.”

This research definitely sounds cool, but will it ever be available to the public? The ETH researchers hope so—they are collaborating with a partner from industry to bring their coating to market. And even if it sells for more than current anti-fog sprays, you may find it worth the investment. “We’re looking to refine our already robust coating to ensure it lasts for years,” Walker explains.

That’s a far cry from the daily applications required by normal anti-fog sprays!

Credit: ETH Zürich, YouTube