The surface texture, which was inspired by lotus leaves and moth eyes, has an array of nanoscale cones that have a base width of 200 nanometres. The cones give the glass a rough surface that repels water, and their refractive index minimises reflection.It is consequently self-cleaning. In fact, this glass is based on surface nanotextures that produce an array of conical features.
The glass texture is built using coating and etching techniques adapted from the semiconductor industry. A glass surface is coated with several thin layers, including a photoresist layer, which is then illuminated with a grid pattern and etched away until the cone shapes appear.According to these MIT researchers, David Chandler writes, this material may be resistant to raindrops in a strong downpour, wind-driven pollen, grit, and direct poking with a finger. Taking photovoltaic panels as example, mechanical engineering graduate student Kyoo-Chul Park, one of the co-authors of a paper on this technology published in the journal ACS Nano pointed out:
Photovoltaic panels can lose as much as 40 percent of their efficiency within six months as dust and firt accumulate on their surfaces. But a solar panel protected by the new self-cleaning glass would have much less of a problem. In addition, the panel would be more efficient because more light would be transmitted through its surface, instead of being reflected away — especially when the sun's rays are inclined at a sharp angle to the panel. At such times, such as early mornings and late afternoons, conventional glass might reflect away more than 50 percent of the light, whereas an anti-reflection surface would reduce the reflection to a negligible level.
According to Park and co-researcher Hyungryul Choi,
Glass or transparent polymer films might be manufactured with such surface features simply by passing them through a pair of textured rollers while still partially molten.Nature appears to have been a greatly inspiration, where textured surfaces ranging from lotus leaves to desert-beetle carapaces and moth eyes have developed in ways that often fulfill multiple purposes at once.
This material is not yet available as this is an expensive manufacturing process, both David Chandler and Mark Brown write. Nonetheless this interesting nanotexture material, beyond smartphones, microscopes, cameras, televisions and solar panels, may even be used for windows in buildings.
MIT makes glass that repels water, eliminates glare, shrug off fog | Mark Brown || Wired UK
Through a glass, clearly | David L. Chandler || MIT News