Foggy lenses have been plaguing glasses wearers for as long as they’ve existed. It typically happens in the winter, when people are entering warm buildings or vehicles from outside. With the ongoing pandemic, however, it’s even more common as masks don’t form a tight enough seal around the nose to prevent warm air from going behind the lenses as an individual exhales. When it hits the lenses, which are colder than the surrounding air, it will cause the moisture to condense into visible drops; this leads to fogging.
The same problem affects car windows, where the warm air condenses on the inside while the outside remains called; this can make it difficult for people to see through their windshields in the winter. A simple solution is to heat the windows using ho t air from vents or thin embedded wires. However, this isn’t really an option for glasses, which are designed to be comfortable and lightweight to wear.
The good news is that ETH Zurich researchers have recently come up with a way to prevent glasses from fogging. That is, they’ve developed a type of invisible glass coating—one that will readily absorb heat. Made from thin clusters of gold, the coating, which is approximately 10 nanometers thick, is sandwiched between thin layers of titanium oxide, a substance that naturally has electrically insulating properties.
This extremely thin layer of gold will absorb infrared light from the sun; this will heat up the lenses by up to eight degrees celsius. In doing so, moisture from the air will not condense on the lenses. Not only that but the coating also allows for all visible light from the sun to pass through. In other words, it’ll be completely invisible to the naked eye. And because it’s so thin, it can be applied to curved surfaces.
Having said that, there are a few drawbacks to the new approach. For one thing, the gold coating requires energy from the sun to heat up so it may not be as effective during the winter, when it gets dark by late afternoon. Because gold is such a great conductor, however, researchers believe that it may be used with a small hidden battery, one that will provide it with a small amount of electricity.
Another issue is price. After all, gold is one of the most sought-after metals on earth and is in high demand. Still, researchers are optimistic about its potential.
