Joanna Aizenberg, Ph.D. and her team at the Wyss Institute for Biologically Inspired Engineering at Harvard University have improved upon the Slippery Liquid-Infused Porous Surfaces (SLIPS) technology they developed back in 2012. The ultra smooth surface, which the team claims is the slipperiest known synthetic surface, has now been made transparent and more durable, giving it the potential to make the issues glass has with sticky liquids, frost and ice formation, and bacterial biofilms a thing of the past.
Instead of lotus leaves, which have been the inspiration for numerous superhydrophobic surfaces, the SLIPS technology was bio-inspired by the carnivorous pitcher plant, which has incredibly slippery leaves that help it trap unsuspecting insects. By now making it transparent and longer-lasting, Aizenberg says they have extended SLIPS' potential to durable, scratch-resistant lenses for eyeglasses, self-cleaning windows, improved solar panels, and new medical diagnostic devices.
To create the new coating, the researchers placed particles of Styrofoam (polystyrene) on a flat glass surface, and poured liquid glass on them until the particles were half submerged. Once the liquid glass solidified, the particles were burned away, leaving what the team describes as a "network of craters that resembles a honeycomb." The researchers then covered the craters with the same lubricant coating used in SLIPS.
The researchers found that the flat, glass slides treated in this way were more rugged than flat surfaces simply treated with the SLIPS coating, but they remained equally slippery, repelling everything from wine, olive oil, ketchup and octane. They also repelled water, thereby preventing the build up of ice, giving it the potential to keep power lines, aircraft and cooling systems frost-free.
The researchers found that by reducing the diameter of the individual honeycomb cells to less than the wavelength of visible light, the coating became transparent, while retaining its robustness and slipperiness.
Now that this method has been proven, the researchers are working to improve it to make it easier to apply to curved glass and clear plastics.
The video below shows a demonstration of the new coating on curved watch glass.
Source: Wyss Institute