The best new technology often comes from its exact opposite—nature. Case in point, the Humboldt squid, which manage to use a hard, razor sharp beak to kill and rip up prey with no damage to their own squishy, gelatinous bodies.
Scientists liken the squid’s beak to an exacto blade embedded in a cup of jello. How do you cut anything with the blade without ruining the jello?
Biologists and engineers from UC Santa Barbara have figured out how the squid does it, and want to imitate its beak for their own purposes—like making better interfaces between artificial implants and human tissue.
“It represents a natural design event that really ought to be mimicked,” says Herb Waitte, biologist and lead author of the study published in Science on March 28.
The squid’s trick says Waitte, is that the beak is not uniformly hard. It gets progressively softer as it moves towards the base. The reason for this has to do with the distribution of chitin, a flexible yet tough carbohydrate, and proteins and the way they interact with each other and their aquatic environment.
Chitin is extremely concentrated at the beak’s base, but is more diffuse at the tip. Certain proteins, on the other hand, congregate at the tip but become more spread out closer to the base. Chitin interacts with the surrounding water, allowing the squid’s body to be more sponge-like, and the proteins crosslink to each other, which makes the beak denser where there are more proteins, and squeezes the water out.
At the base of the beak where there are less proteins and more chitin, the squid becomes progressively softer. When the squid is out of water however, there is no change in hardness since there is no water to squeeze out.
“It’s like the proverbial razor blade in the jello,” Waitte says.
Waitte says that density gradients like in the squid beaks could be useful for many biomedical applications such as hip replacements and pace makers. A hard, dense artificial hip has the potential to do a world of harm to the surrounding tissue and bone. But if we can engineer it so that it’s softer at its interface it would make for a much more comfortable hip.
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