Anyone who skis, wears glasses, and uses a camera to drive a car is familiar with the title question: If you get into a damp scene from a cold scene, your glasses, the camera lens will probably fog quickly. Researchers at the Federal Institute of Technology in Zurich have not yet demonstrated a new type of transparent material coating that can greatly reduce that effect. Only a few nanometers thick, their durable coatings are made of gold nanoparticles embedded in non-conductive titanium oxide.

“Our coating absorbs the red components of sunlight and a small fraction of the visible sunlight and converts light into heat,” explains Christopher Walker, Ph.D. student at Dimos Poulikakos, Professor of ETH. The author of the study. That heats the surface by 3 to 4 degrees Celsius. It is the temperature of that type that obstructs atomization.

Passive heating

Heat is also the answer to the problem of window fogation title. The front windshield is heated by the warm air that heats the swarf from the car, while the rear window is equipped with a grid of electric heating elements. But unlike those methods, the new coating from ETH researchers is passive. Since the required ONLY energy source is the sun, their coatings are tailored to wearable items such as glasses and goggles.

Efstratios Mitridis , another Phulikakos doctoral student, explained that the new surface coating is so special: “Under the scene, it is a black surface that absorbs light and converts it into heat,” he said. “But we created the invention. A transparent surface, the same effect."

Better than anti-fog spray

Whenever the temperature drops suddenly and the humidity increases, the surface will erupt and condense, forming a strong water droplet, which makes the incident light disperse in a different way, which is roughly different from the method of atmospheric fog. As a generational idea of using heat to apply fogging, the susceptible surface may be coated with a hydrophilic agent. Since they attract water, those reagents ensure that the condensation is forming a uniform thick film liquid on the surface and that the droplets are dispersed. Antifogging sprays for spectacles are often based on this.

Now, tests have shown that the atomized surface coated with gold nanoparticles and titanium oxide is four times faster than the surface treated with conventional anti-fogging agents when exposed to sunlight. "After a while, the spray treatment tends to lose its sense, because the anti-fog film is about to spread out evenly," Walker said. “A durable coating like ours lasts longer than the spray process, and you have to apply it every day ,” he compensated.

ETH scientists are now envisioning working with industry partners to bring their new methods to market. “We are looking to improve our unstrength coatings to ensure they last for many years, and we want to expand our skills from lab scale to property size,” Walker said. Their coatings have a wide range of concealed applications, sweeping the car's windshield and rearview mirrors, as well as ski goggles and diving masks.

Further exploration: new anti-frost and anti-fog coatings for glass

More information: Christopher Walker et al. The transparent super surface compensates for sunlight, and the nano-letters counteract atomization (2019). DOI: 10.1021 / acs.nanolett.8b04481