MIT Creates Some Of The Most Water-Resistant Material On Earth By The Wings Of A Butterfly
ByEver wonder how certain leaves seem to remain dry no matter how wet they get or how a butterfly navigates through a rainstorm? It's all about texture.
A group of MIT professors and former post doc students used nearly the same principles found in nature to create a substance that reduced the amount of time it took water to bounce from a surface by 40 percent. Basically, they created some of the most water-proof material on earth, according to MIT's news page.
The logic behind MIT's invention defied traditional thinking. Previous research dictated a theoretical limit to the amount of time it took water to rebound off a substance and the best way to approach that limit was to reduce the adhesiveness of the substance, according to MIT.
But MIT professors and students tend to think beyond limits. Rather than lessen the stickiness of the contact point (typically accomplished by minimizing water-surface interactions via a smoother surface), they did the opposite and increased surface activity by adding textural features like ridges, similar to the veins on nasturtium leaves or the topographical quality of butterfly wings, MIT reported. More surface activity enabled researchers to achieve water speeds previously deemed impossible. Thus, the experimental surface stayed 40 percent drier than control surfaces.
"The time that the drop stays in contact with a surface is important because it controls the exchange of mass, momentum, and energy between the drop and the surface," Kripa Varanasi, study co-author and professor of mechanical engineering at MIT, told MIT.edu. "If you can get the drops to bounce faster, that can have many advantages."
"We've demonstrated that we can use surface texture to reshape a drop as it recoils, in such a way that the overall contact time is significantly reduced," added former MIT postdoc James Bird, the paper's lead author. "The upshot is that the surface stays drier longer if this contact time is reduced, which has the potential to be useful for a variety of applications."
Indeed, water-resistant material has a wide variety of applications, for as much as water is the key to life, it is also incredibly damaging. Bird's material could be configured to the wings of air planes and used to prevent water droplets from freezing, according to MIT. The material would have similar effects on turbine blades in power plants. Keeping them drier would make the process more efficient.
Encouragingly, water-proofing substances by MIT's method is relatively easy, requiring only basic mining tools to create the ridges, according to Varanasi. Perhaps because of how straightforward the process is, Varanasi believes they can significantly improve it.
"I hope we can manage to get a 70 to 80 percent reduction," she said.