It can be more than a little frustrating when your glasses fog up — just ask anyone who has worn a face mask over the past two years of the pandemic. Nanotechnology might soon keep your vision clear, however. ETH Zurich researchers have developed a gold nanocoating that heats glass by up to 46F by absorbing a large amount of infrared radiation, keeping your glasses fog-free in many humid conditions. And unlike conventional approaches, which merely spread water around using hydrophilic molecules, this prevents the condensation from even starting.
The 10nm thick coating sandwiches gold between layers of titanium oxide that not only amplify the heating effect through refraction, but protect the gold against wear. The design also won't lead to overheating in warm weather as it prevents radiation from reaching the other side. ETH is keen to point out that it made the coating using techniques common to manufacturing, such as vacuum-based vapor deposition in a clean room. Companies might not have to revamp their production lines, in other words.
Before you ask: it's not as expensive as you think. While gold is a pricey material, the amount needed is so small (it's about 12 times thinner than a typical gold leaf) that it shouldn't add much to the price of your glasses. Nonetheless, the team plans to study the use of other metals.
You may still have to wait a while before finding gold-coated glasses at your local store. Although the discoverers have applied for a patent, there aren't companies lined up to adopt the invention. It might not be limited to eyewear, thankfully. The research group sees the layer as useful for reducing fog on car windshields, and future implementations could be useful for mirrors, windows and many other transparent surfaces that need to stay warm.