Can you say superhydrophobic three times real fast? Yeah, me neither. This is a term that describes something that is extremely resistant to water. If you were superhydrophobic, you would emerge the clear winner in any water gun fight. However, I shall get back to the point. Researchers have long marveled at how the lotus leaf, pictured below, repels water. Its surface is so smooth that water and dirt cannot adhere to it. To achieve this super water repellency on a surface, there have to be structures in place which force air between the water and the surface of the leaf. Researchers have mimicked this effect by developing a surface that allowed them to print letters in the air layer between it and the water above it.
Dr. Robin Ras of Aalto University in Finland lead the study along with researchers from University of Cambridge and Nokia Research Center Cambridge. You can watch a really neat display of this technology at work via this link http://youtu.be/AEWPIjLbrSE. It is pretty impressive to see how they carried this research out. They squirt water directly onto the surface where below, you can see the word “Nokia”. The water just bounces off the surface until it is completely covered. In an effort to keep this simple, what basically happens because of the presence of nano-scale posts on the surface, a layer of air is trapped between the superhydrophobic surface and the water above it. Because of the way the posts are designed, the shape of the air can exist in two “wetting” states. The researchers refer to this as “reversible switching”. All it takes is a pressure change to change the shape of this air layer. “The minimal energy needed to switch between the states means the system is bistable, which is the essential property of memory devices, for example”, Academy Research Fellow Dr. Robin Ras points out. However, there is a feature that makes it all the more interesting: there is a striking optical contrast between the states due to a change in the roughness of the water-air interface. “Combined with the optical effect, the surface is also a bistable reflective display.” Video is also embedded below.
Who knows where this research could lead? It could have applications such as lower power data storage all the way to low power displays. The amazing thing to me is that the original idea came from observing nature. There is so much discovery left in this world and so much to learn. If only, we took more time to ponder nature’s wonders, who knows what amazing innovations we might achieve.
For more information on this research, you can view the published study on the Proceeding of the National Academy of Sciences website at http://www.pnas.org/content/early/2012/06/05/1204328109.