Gold nano coating prevents glass from fogging in winter

The team at ETH Zurich designed a new coating material from gold nanoparticles that warms the glass and prevents condensation from obstructing vision.

Compare lenses with coating (right) and lenses without coating. Photo: ETH

Developed by a team of experts at ETH Zurich, the new coating uses heat but does not require electricity. Instead, this coating uses a layer of nanoparticles sandwiched between two ultrathin layers of titanium oxide. The entire coating is just 10 nanometers thick, about one-tenth the thickness of a gold leaf, according to research led by professors Dimos Poulikakos and Thomas Schutzius published December 12 in the journal Nature Nanotechnology .

The nanoparticles absorb much of the infrared spectrum of the incident light, causing the coating to heat up to 8 degrees Celsius above the surrounding temperature. However, the nanoparticles absorb very little visible light, causing the coating to remain transparent.

The refractive property of titanium oxide enhances the effectiveness of the thermal effect. In addition, the outer layer also contributes to protecting the gold from abrasive effects. Another plus is that because the gold layer conducts electricity, an energy source such as a battery can be used to heat the coating when direct sunlight is not available.

Compared with anti-fogging glass with water-absorbing molecules, the gold nano-coating prevents fog from settling on the glass in the first place. The technology was first introduced in 2019. However, compared to the coating described at the time, the new coating is much thinner, more flexible and transparent due to selective absorption of infrared light. The researchers used very little gold in the coating to save costs. They are still looking for cheaper metals to replace gold.