High-Tech Lens Treatment Can Permanently Prevent Glasses From Fogging Up

Scientists at NTU Singapore have developed a new type of coating that, when applied to a plastic surface, prevents fogging and "self-cl...

Scientists at NTU Singapore have developed a new type of coating that, when applied to a plastic surface, prevents fogging and "self-cleans", eliminating the need for frequent reapplication.

No one likes fogged glasses or lenses, and unfortunately, most anti-fog products need to be reapplied frequently. However, new technology could make polycarbonate lenses permanently fog-free... and self-cleaning too.

Durable, thin two-layer silicon dioxide and titanium dioxide coating

The process, developed at Singapore's Nanyang Technological University, begins by treating a lens (or another plastic surface) with an oxygen plasma. This is done both to clean it and to improve the adhesion of the thin film that will subsequently be applied to it.

This transparent film consists of two layers - one of silicon dioxide, the other of titanium dioxide - and is applied to the plastic using a pulsed laser deposition process. This process involves using a laser to vaporize each of the two layers of material in a vacuum chamber. As the evaporated silica and titanium dioxide rise to the top, they are finely deposited on a plastic substrate that sits on top of the chamber.

As with other anti-fog coatings, this coating works by causing tiny water droplets that settle on the lenses to spread into a uniform film that is easy to see through. This happens just 93 milliseconds after the drop hits the film.

Testing also showed that the film resisted abrasion when rubbed with a piece of gauze (a standard test method for abrasion resistance), and also remained glued to plastic when cellophane tape was applied to it and then peeled off. And as an added bonus, when treated plastic is exposed to sunlight (or another UV source), titanium dioxide begins to break down organic contaminants such as dirt particles and bacteria.

"These results prove the versatility of our coating," said graduate student Sun Ye, the study's first author. "It is anti-reflective, anti-fog, and self-cleaning. In addition, the coating approach is quick and easy to implement, while being highly durable. This makes our innovation unique among other anti-fog methods that typically end up with limited-function coatings."