People who wear glasses often face the problem of fogging them up, especially during the cold season. Most modern solutions designed to combat this phenomenon need to be reapplied regularly. New technology can make glasses anti-fog and self-cleaning.
A special way of processing lenses was invented at the Nanyang Technological University of Singapore. It consists in the use of oxygen plasma. This is done both to clean the plastic surface and to improve adhesion with a special thin film that is subsequently applied to the lens. It consists of two layers. The first is made of silicon dioxide, and the second is made of titanium dioxide. They are fixed to the plastic using a pulsed laser deposition process.
This technology uses a laser to vaporize each of the two-layer materials in a vacuum chamber. Evaporated dioxides rise and settle in small particles on a plastic substrate located at the top of the chamber. When tiny droplets of water get on the lenses of the glasses, they spread into a homogeneous film with sufficient transparency. The whole process takes only 93 milliseconds from the moment the drop hits the coating.
Tests have shown that the film is resistant to rubbing glasses with a gauze cloth. Even when sticking adhesive tape on the lenses and then peeling it off, the applied coating is preserved. When exposed to sunlight, the titanium dioxide on the film begins to work and break down organic contaminants such as dirt particles and bacteria.
“The presented results prove the versatility of our development. It is anti-reflective, anti-fog and self-cleaning. In addition, its production is quick and easy, and the service life is long. This makes our innovation unique among other anti-fog methods that typically end up with limited function coatings,” said study lead author Sun Ye.