British researchers have developed self-cleaning smart glass that can limit glare by utilising principles found in the eyes of moths.
The glass, developed by a team from University College London (UCL), is extremely resistant to water, meaning that raindrops simply wash away on its surface, taking all dirt with them.
The surface layer of the glass is formed of an elaborate nanostructure composed of conical shapes that trap air. Thanks to this nanostructured layer, only a very small amount of water actually comes in contact with the surface of the glass. The surface of normal glass does not repel water, meaning that raindrops slide down quite slowly, leaving dirty marks behind.
The technology would be particularly helpful in skyscrapers with their large glazed walls that require cleaners to work high above the ground.
“It’s currently estimated that, because of the obvious difficulties involved, the cost of cleaning a skyscraper’s windows in its first 5 years is the same as the original cost of installing them,” said Ioannis Papakonstantinou of UCL, who led the project. “Our glass could drastically cut this expenditure. As the trend in architecture continues towards the inclusion of more glass, it’s vital that windows are as low-maintenance as possible.”
The surface nanostructure of the smart windows is quite similar to that found in eyes of moths and other insects, which enables them to filter out glare by up to 95 per cent. This feature, evolved by the moths to enable them to spot predators faster, can considerably increase comfort of people working in glass-walled buildings.
Moreover, the glass is coated with a thin film of vanadium oxide that prevents heat from escaping. This system helps to maintain comfortable temperature inside in all weather. In cold, warmth can’t escape from outside, while during hot periods, infrared radiation from the Sun cannot enter the building.
The researchers said that choosing vanadium oxide enabled them to achieve considerable cost savings, as the material is abundant and much cheaper than current silver and gold-based coatings used in energy saving windows.
The UCL team estimates that the windows could reduce bills for heating by up to 40 per cent.
The team, which received backing from the Engineering and Physical Sciences Research Council, is now working on manufacturing methods that would allow scaling up the production and hopes to have the windows in the market within three to five years.
“We also hope to develop a ‘smart’ film that incorporates our nanostructures and can easily be added to conventional domestic, office, factory and other windows on a DIY basis to deliver the triple benefit of lower energy use, less light reflection and self-cleaning, without significantly affecting aesthetics,” Papakonstantinou said.