Earwig’s wing inspires compact designs that fold themselves

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I have to admit that even as someone who is fascinated by most insects, the earwig freaks me out. Upon seeing one, I'm typically too busy trying to squash it to notice any details about its anatomy. So it was a bit of a surprise to find out that not only do they have wings, but their wings are world record holders in a specific aspect of insect winginess: they take up the least space when folded compared to their extended size. The ratio between these states can reach as high as 18-to-one.

 

With that fact in mind, I was less surprised to find out that researchers have decided to study this bit of biology to see if they can derive any insights from what evolution has done with the earwig. In today's issue of Science, there is a report on what has been learned by three researchers: Jakob Faber and André Studart of ETH Zurich and Andres Arrieta of Purdue University. They find that, to mimic the earwig's wing, an origami-style folding approach won't do. Instead, they have designed and 3D-printed a selection of meta-stable designs that, with a small input of energy, rapidly flip between folded and unfolded states.

 

When many people, including most materials scientists, think of folding, their first thought is origami. But the research team found that the earwig's "exquisite natural folding system" behaves in a way that "cannot be sufficiently described by current origami models." Part of the issue is one of materials science: there are certain folding patterns in the wing that just can't be done by creating a crease in a single material or using the straight lines of origami. In addition, the wing is bi-stable, holding itself in place during flight with minimal input from muscles and folding up entirely without any muscular energy being expended.

 

The secret to this is partly that biology is not limited to either straight lines or a single material. In fact, the joints on an earwig's wing are rich in a protein called resilin, which forms a flexible polymer that can store and release energy as it is bent and relaxed.

 

Source: Link