A team of Harvard material scientists has engineered a coating for glass that makes it self-cleaning and scratch resistant.
It means that not only will you never have to rub down your glasses again, but huge amounts of money and energy could be saved by not having to clean solar panels. Although a report was released at the end of July in Solar Energy claiming it was not, economically speaking, worth cleaning solar panels, the study still found that panels that had not been cleaned and had gathered dust over 145 days lost 7.4 percent efficiency. This didn't stack up against the cost of cleaning, but if the new coating from Harvard were cheaply available it would mean retaining the 18.5 percent efficiency the panels are in danger of losing over the course of a year.
The material is an extension of another coating called Slippery Liquid-Infused Porous Surfaces (SLIPS), and has been engineered by Joanna Aizenberg of the Wyss Institute for Biologically Inspired Engineering at Harvard University and colleagues at the Harvard School of Engineering and Applied Sciences (SEAS). As the name suggests, the coating is also super slippery, as well as being permanently clean and durable due to its liquid resistant surface. Unlike its predecessor SLIPS, it's also transparent. This is achieved by combining SLIPS with pieces of glass in a precise honeycomb pattern.
The team placed tiny balls of polystyrene on a flat piece of glass and proceeded to pour liquid glass on top of it. Once it reached about half way up the balls, it was left to call and the balls were then burnt off to leave a honeycomb pattern indented into the sheet of glass. At this point, the SLIP lubricant was poured over. Having SLIPS arranged in a honeycomb pattern is what is responsible for the material's newfound strength and durability. The surface even remained slippery after have things like pieces of tape stuck on and peeled off, and it proved to remain resistant to liquids including water, wine, olive oil and ketchup.
A lot of the material's success is down to the honeycomb pattern. It's what makes it durable, but interestingly it's what also makes it transparent according to a study on the application published in Nature Communications. By making the width of the individual honeycomb cells smaller than the width of a wavelength of visible light, the coating appears transparent.
The material, once applied to the glass, was also resistant to frost, ensuring its durability in all conditions.
"We set ourselves a challenging goal: to design a versatile coating that's as good as SLIPS but much easier to apply, transparent, and much tougher -- and that is what we managed," commented Aizenberg in a statement.
The project was part-funded by the Air Force Office of Scientific Research, suggesting the material could be slated for reinforced, frost-resistant jet plane windows, considering some models can reach altitides upwards of 21,000m, at speeds of more than 800km/h. Of course, it could also mean never having to clean your Google Glass.
