杏吧原创

Taking a leaf out of plants鈥� book could help us prevent frost on aeroplanes and car windows, and even allow us to ditch antifreeze.

Kyoo-Chul Park at Northwestern University in Illinois and his colleagues devised a way to prevent frost by mimicking the veins of leaves. 鈥淚 was walking around and I was fascinated by the beautiful frost pattern on fallen leaves,鈥� says Park. 鈥淚 was wondering why we see that kind of frost pattern, rather than just 100 per cent coverage of frost.鈥�

The pattern is caused by the shape of veins on the leaves. On their front side, where the veins protrude, frost forms on these and not on the rest of the leaf surface. On the back, the resulting depressions where the veins are don鈥檛 get covered in frost.

Park and his team used ridged aluminium sheets to mimic this effect. They found that water droplets tended to form and then freeze at the ridge peaks, leaving the valleys free of ice. Simulations of this process showed that this freezing at the peaks causes any water droplets in the valleys to evaporate, making it impossible for ice to form there.

Even when the researchers boiled the aluminium to turn it hydrophilic 鈥� to make its molecules tend to hold on to water 鈥� the valleys continued to remain frost-free zones. 鈥淭his work shows ways to reduce frost coverage to as low as under 20 per cent,鈥� says Park. Many other defrosting methods only temporarily delay frost coverage rather than decreasing it, he says.

Simply adding ridges to objects like aeroplanes or windows could drastically decrease how much frost forms on them, says Park. This could be useful for cars and buildings in cold areas where visibility is important.