Materials

High-tech lens treatment could render glasses permanently fog-free

High-tech lens treatment could...
Shown here on an eyeglass lens, the thin film could also be applied to camera lenses
Shown here on an eyeglass lens, the thin film could also be applied to camera lenses
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Shown here on an eyeglass lens, the thin film could also be applied to camera lenses
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Shown here on an eyeglass lens, the thin film could also be applied to camera lenses
An untreated piece of plastic fogs up when placed over hot water (left), while a treated sample resists fogging
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An untreated piece of plastic fogs up when placed over hot water (left), while a treated sample resists fogging

Nobody likes fogged-up glasses or goggles, and unfortunately most anti-fog solutions need to be frequently reapplied. A new treatment, however, could make polycarbonate lenses permanently fog-free … and self-cleaning, to boot.

Developed at Singapore's Nanyang Technological University, the process begins with the lens (or other plastic surface) being treated with oxygen plasma. This is done both to clean it, and to improve the adhesion of a thin film that will subsequently be deposited onto it.

That transparent film is made up of two layers – one consisting of silicon dioxide, the other of titanium dioxide – and it's placed on the plastic via a pulsed laser deposition process. The latter involves using a laser to vaporize each of the two layer materials within a vacuum chamber. As the vaporized silicon dioxide and titanium dioxide rise upwards, they're finely deposited on the plastic substrate, which is located at the top of the chamber.

As is the case with other anti-fog coatings, this one works by causing tiny water droplets – which settle on the lens – to spread out into a uniform film that is easily seen through. It does so within just 93 milliseconds of a droplet touching the film.

An untreated piece of plastic fogs up when placed over hot water (left), while a treated sample resists fogging
An untreated piece of plastic fogs up when placed over hot water (left), while a treated sample resists fogging

Tests also showed that the film resisted abrasion when rubbed with a cheese cloth pad (a standard abrasion-resistance testing technique), plus it remained bonded to the plastic when adhesive cellophane tape was applied to it and then peeled away. And as an added bonus, when the treated plastic is exposed to sunlight (or another ultraviolet light source), the titanium dioxide is triggered to break down organic contaminants such as dirt particles and bacteria.

"The reported results prove the multi-functionality of our coating," said PhD Student Sun Ye, first author of the study. "It is antireflective, anti-fogging, and self-cleaning. Additionally, the fabrication approach is fast and easy to implement with great durability. This makes our innovation unique among other anti-fogging methods which tend to end up with coatings with limited functions."

Source: Nanyang Technological University

7 comments
7 comments
paul314
How well does this continue to work as soon as it gets covered with a thin layer of oils, as typically happens when people wear and handle their classes for a while. Do we have to clean it with oxygen plasma again?
vince
If only they had that invention BEFORE the Covid virus forced many sight impaired to hang up the glasses when having to wear a mask. The fogging was unacceptable so something had to give--usually the glasses.
Vince
I hope motorcycle helmet manufacturers read about this development.
pmshah
So will every photo optometrist have to buy this deposition equipment or will this be outsourced service. How will his work when the lenses have to be ground to prescription?
Rick O
paul314, the plasma process is before coating, to help it adhere. It's common in surface treating plastics before coating. The SiO2 and TiO2 shouldn't be affected by oils, and would be relatively tough.

pmshah, this would be something done when you order lens, and thus done in a factory type setting. Similar to when you get glare coatings, etc done for glasses.

I'm curious to see how transparent it really is. Hard to tell from the supplied pics, but seems a bit cloudy, which is obviously not ideal. I also wonder if the laser method is needed for the deposition process, or if standard e-beam processes would suffice. Although, e-beam might heat the lenses too much.
ljaques
Yes, the covid debacle sure brought out the weak link in the mask-wearing concept. Most masks were made without nose bridge support which would have allowed you to form fit the mask to your nose. Fitting ensured that it would not fog up your eyeglasses. And many other masks were made with entirely insufficient bridge supports. I added wire support to every mask I've worn in the past 2 years which didn't have proper support, about 80% of them. I truly hope this method fixes that. I had problems with the anti-glare coating which put something like a matte finish on my lenses. It required physically washing my glasses in warm soapy water 6+ times a day due to fingerprints which would not wipe off. Please, researchers, let's avoid that in future coatings.
Steve Jones
Great. Now stick it on my VR headset.
Why do these things all take so bloomin' long to come to market?