Nano-tech boffins haven't the foggiest

Undeterred by fears of nanotechnology turning the world to grey goo, a group of US scientists have come up with a way of using nano-particles to stop windows and glasses from steaming up.

The team at the Massachusetts Institute of Technology (MIT) have developed a polymer coating made of silica nanoparticles that they say can create clear glass surfaces that never become foggy.

The transparent coating can be applied to eyeglasses, camera lenses, ski goggles and even bathroom mirrors, according to the researchers.

"Our coatings have the potential to provide the first permanent solution to the fogging problem," said study leader Michael Rubner, a materials science researcher at MIT.

"They remain stable over long periods, do not require light to be activated and can be applied to virtually any surface."

Coated glass appears clearer and allows more light to pass through than untreated glass while maintaining the same smooth texture.

When fogging occurs, thousands of tiny water droplets condense on glass and other surfaces. The droplets scatter light in random patterns, causing the surfaces to become translucent or foggy.

The coating prevents this process from occurring, primarily through its super-hydrophilic, or water-loving, nature.

"The nano-particles in the coating strongly attract the water droplets and force them to form much smaller contact angles with the surface," said Rubner.

"As a result, the droplets flatten and merge into a uniform transparent sheet rather than forming countless individual light-scattering spheres."

Rubner explained that the newly developed coatings consists of alternating layers of silica nano-particles, which are tiny particles of glass, and a polymer called polyallylamine hydrochloride, both of which are relatively cheap to manufacture.

A patent has been applied for covering the nano-coating's manufacturing process and Rubner said it could be available in consumer products in two to five years.