Chinese scientists have developed a fog-free, self-cleaning glass coating with a structure that mimics that of the lotus leaf—and takes a page from the raspberry, too.

The coating, by researchers at the Chinese Academy of Sciences, imparts a “clear, slick, water-repellant surface” to glass and other transparent materials.

Ralf Pfeifer/ Wikimedia Commons

The lotus leaf’s superhydrophobic surfaces excel at repelling water and boast other “smart” self-cleaning, anti-glare, anti-icing, and anti-corrosion properties, scientists say.

The scientists say they were inspired by the leaf’s water-repellent and other properties. The coating also employs hollow silica nanoparticles that resemble raspberries, they said.

Tomorrow’s Materials

The coating holds potential for tomorrow’s materials, the team reports.

By “modifying low-surface-energy materials and creating surface textures on them, surfaces can be made to exhibit completely different wetting characteristics—either repelling or attracting moisture,” according to the American Institute of Physics (AIP), which published the research in Applied Physics Letters.

The research is described in “Transparent superhydrophobic/superhydrophilic coatings for self-cleaning and anti-fogging.” 

The article notes that superhydrophobic surfaces have demonstrated important self-cleaning, antireflection and anti-icing properties. Superhydrophilic surfaces, meanwhile, provide antireflection and anti-fog properties.

Applied Physics Letters

Two views (a and b) show the fogging differences between coated superhydrophilic glass and bare glass. The bottom row shows the fogging differences between (c) superhydrophobic glass and (d) bare glass.

“Recently,” the team notes, “there have been increasing interest in multifunctional transparent superhydrophobic or superhydrophilic films displaying antireflection or anti-fog, which can greatly extend their utility in the fields such as windshields, solar cell, and optical devices.”

‘Fog-Free Performance’

In the current experiments, the finished surfaces exhibited good anti-fogging and light-transmittance properties before and after chemical modification, the authors say.

The “results reveal that evaporation rate of the fog on superhydrophobic surfaces can be tremendously improved,” the team writes.

That could mean “clearer, fog-free performance” for windshields, windows, solar cells and panels, LEDs, TVs, tablets, and cell phone screens.

Such “smart coatings” are highly desirable, especially for solar cells and panels, which frequently lose up to 40% of their efficiency to dust and dirt buildup within a year of installation, the AIP said.

The next challenge for the scientists: move the smart surfaces from the lab to industry in a cost-efficient manner, the AIP said.