Researchers at the ETH Zurich have developed a transparent coating (Gold-based heat exchanger for glass) with shiny gold that can convert sunlight into heat. It can be placed on glass and other objects to prevent them from jumping. Applications for glasses include eye-wear, car glasses etc.,
Researchers in the group of ETH experts Dimos Poulikakos and Thomas Schutzius point out that their coatings are produced using widely used techniques. In a clean room and using a vacuum cleaner, a small amount of gold is placed on top. ETH Zurich has filed a patent on the cover.
Absorbs most of the infrared radiation
The unique feature of the new cover is that it is selective for the sun’s rays. Half of the energy in sunlight resides in the infrared range, the other half in the range of visible light and UV radiation. “Our coating absorbs a large part of the infrared radiation, making it warmer – up to 8 degrees Celsius,” explains ETH doctoral student Iwan Hächler, which is one of the reasons the development. It absorbs only a small part of the radiation in the visible range, so the coating is transparent.
The new insulation takes a different approach to foam insulation. Traditionally, the surface is covered with hydrophilic water, which results in an even distribution of condensation. This is how anti-fog sprays work. But the new system heats the surface, preventing the condensation caused by the water in the first place. It is the same principle as that used for the rear window of a car. But, according to Hächler, electricity is ineffective and wastes energy. On the other hand, the new cover is warm and does not require any additional energy during the day.
Thin, flexible and efficient
Poulikakos, Schutzius and their team have been working on thermal insulation for many years. Three years ago, scientists published their first research paper on a gold coating that prevents the shiny objects from getting too high (see previous ETH reports). The coating they presented now has many advantages over the first one: it is made from a gold nanolayer and is very thin, which makes it transparent and flexible. In addition, it is more reflective and more efficient because it prefers infrared light.
Gold may be expensive, but the analysts point out that it requires less coverage as asset prices remain low. The cover consists of small clusters of beautiful gold between two ultrathin layers of titanium oxide, an electrical insulator. Because of the factors that make them reactive, the above double layer improves the efficiency of the light source. In addition, a layer of titanium oxide acts as a finish that protects the gold layer from wear. This entire “sandwich” is only 10 nanometers. For comparison, ordinary gold leaf is 12 times larger.
Individual gold clusters lightly touch each other, allowing the gold layer to begin conducting electricity. Therefore, in the absence of sunlight, it is still possible to use electricity to heat the roof.
Researchers will further develop the coating for other applications. In this process, they will analyze whether other metals work as well as gold. In addition to windshields and windshields, this anti-fog method can be used anywhere that needs to be warm and clear, such as windows, mirrors or optical sensors.
However, there is no need to fear that it will make the car or house hotter in the summer. Hächler, a PhD student at ETH, explains: “The glass coating absorbs infrared rays from the sun, which heats the glass directly and prevents radiation from entering the body.” interior of car or house. As a result, the interior is even warmer than it would be without the liner.”
