Leaves offer a new blueprint for frost-free surfaces
Ice and airplane wings don’t mix particularly well, with the added weight making it hard for the aircraft to take off, or causing it potentially catastrophic problems once in the air. Scientists are continually looking at better ways to address this problem, among them a Northwestern University team that is claiming a new surface coating inspired by leaves can reduce frost formation by up to 60 percent.
The special coating was developed by researchers at Northwestern’s School of Engineering, who took inspiration from the way frost forms, or doesn’t, on leaves. They feature tiny peaks and valleys, presenting a rippling geometry that makes it impossible for frost to build uniformly across their surface.
“People have noticed this for several thousands of years,” said Northwestern’s Kyoo-Chul Park. “Remarkably, there was no explanation for how these patterns form.”
Park and his team investigated this further through computer simulations and experiments to find that while condensation builds up well on the peaks of the leaves, far less of it features in the valleys. What does build up there soon evaporates even when below freezing point, offering a blueprint for a new type of frost-repellent surface.
Further experiments led Park to an optimal design that mimics this natural phenomenon, crafting a surface bearing tiny peaks just a millimeter tall with valleys in between, sloping downwards at angles between 40 and 60 degrees. While a thin layer of frost does build on the peaks, the unique topography and frost-free valleys across the surface enable them to be defrosted far more efficiently.
“The no-frosting region initiates the defrosting process,” Park said. “So it would reduce the materials and energy used to solve frosting problems. All we have to do is provide others with the guidelines to design these serrated surfaces.”
The research was published in the journal Proceedings of the National Academy of Sciences.
Source: Northwestern University
Update March 12: This article originally stated that the researchers took inspiration from mint leaves, rather than leaves generally. New Atlas apologizes for the error.