Biomimicry | Penguins to the rescue of the pylons

Infrastructure could be better protected from ice if it were given a surface similar to penguin feathers, according to a new Montreal study.

Mathieu Perreault
The Press

Biomimicry

“The goal is to manipulate surfaces to give them properties without potentially toxic chemical coatings,” says Anne Kietzig, a materials engineer from McGill University, who is the lead author of the study published this week in the journal Applied Material Surfaces of the American Chemical Society (ACS). “Initially, we were more inspired by plants and their hydrophobic surfaces to create ice-resistant surfaces. We thought: maybe it could also be directly ice-resistant surfaces. A lot of money is spent to reinforce infrastructure such as pylons or rails, or vehicles such as planes, so that they can support the weight of the ice. Otherwise, chemical ice-resistant coatings are used, or de-icing with liquids at airports. »

Biodome

The first iterations of surfaces designed according to the concept of biomimicry were nanotubes, the size of millionths of a millimeter, on mesh structures. “The nanotubes weren’t working, the ice was clinging to them and breaking them,” says Ms.^me Kietzig. But a PhD student realized that once the nanotubes were torn away, the ice didn’t cling to the underlying structure. Another student found that the mesh of the structure resembled the overlapping feathers of a bird. “We said to ourselves: we have never seen a photo of a penguin with ice on its plumage. We asked the Biodôme if they could give us access to penguin feathers. It was a good thing, it was autumn and the penguins had just lost their feathers. »

Limits

Analysis of penguin feathers revealed that the rachis, the solid shaft in the center of the feather, had small scratches crucial to their anti-icing properties. “We were able to replicate these scratches with laser texturing,” says Ms.^me Kietzig. The new mesh proved to be very hydrophobic. The droplets bounce like soccer balls. So the ice does not form. The next step is to understand why this textured mesh is so inhospitable to the ice and to identify the limits of the phenomenon. “If we understand what is happening, and the limitations of this approach, it will be easier to reproduce biomimicry on smoother surfaces used in engineering. In particular, we look at the ideal proportion of voids in the mesh. »

planes

The McGill team conducted tests at the National Research Council’s wind tunnel in Ottawa, a type of laboratory that tests model airplanes. “Icing has been observed on drones and the leading edges of aircraft wings,” says Ms.^me Kietzig. But there are a lot of regulations in aviation, so we think the first applications will be more for infrastructure like pylons and road signs. It is also easier to use mesh directly on these structures. When could we see the first structures inspired by the work of M^me Kietzig? “I have no doubt that we will be able to have products in 5 to 20 years,” says the German-born engineer.