Moth eyes inspire self-cleaning windows

Materials World magazine
2 Mar 2016

What is it?

A new type of smart window that could cut cleaning costs for tall buildings, while reducing heating bills.

Who is involved?

Researchers from University College London, UK, with support from the Engineering and Physical Sciences Research Council, UK.

What inspired the work?

The windows use nanostructures that mimic moth eyes to cut glare and clean themselves.

How is it made?

The windows are engraved with a series of conical nanostructures combined with a thermochromic coating. The nanostructure window traps air and ensures only a small amount of water comes into contact with the surface. The glass is coated with a 5-10 nanometre-thick film of vanadium dioxide, which prevents heat loss during cold periods and blacks infrared raditation from the sun, giving the windows the same anti-reflective properties found in the eyes of moths. 

What could it replace?

The self-cleaning windows reduce the amount of light reflected internally in a room to less than 5% – compared with the 20-30% achieved by other prototype vanadium dioxide-coated energy-saving windows. This reduction in glare should provide a boost in technology for current smart windows.   

What could it be used for? 

The windows reduce heating bills by up to 40%. The glass is suitable for high-rise office buildings and could reach the market in 3–5 years.

The two-and-a-half year research project Biologically Inspired Nanostructures for Smart Windows with Antireflection and Self-Cleaning Properties ended in September 2015 and has received EPSRC funding of around £100,000.