|One of the most instantly recognizable features of glass is the way it
reflects light. But a new way of creating surface textures on glass,
developed by researchers at MIT, virtually eliminates reflections,
producing glass that is almost unrecognizable because of its absence of
glare - and whose surface causes water droplets to bounce right off,
like tiny rubber balls.
The new 'multifunctional' glass, based on surface nanotextures that
produce an array of conical features, is self-cleaning and resists
fogging and glare, the researchers say. Ultimately, they hope it can be
made using an inexpensive manufacturing process that could be applied to
optical devices, the screens of smartphones and televisions, solar
panels, car windshields and even windows in buildings.
The surface pattern - consisting of an array of nanoscale cones that are
five times as tall as their base width of 200nm - is based on a new
fabrication approach the MIT team developed using coating and etching
techniques adapted from the semiconductor industry. Fabrication begins
by coating a glass surface with several thin layers, including a
photoresist layer, which is then illuminated with a grid pattern and
etched away; successive etchings produce the conical shapes.
Since it is the shape of the nanotextured surface - rather than any
particular method of achieving that shape - that provides the unique
characteristics, the team say that in the future 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; such a process would add minimally to the cost of manufacture.