The mantis shrimp, aka the “thumb splitter”, is known for punching its prey. From obliterating clamshells to blowing off crab claws, the mantis shrimp has used its hammer-like appendages to be a force of nature.
When a mantis shrimp’s hammer smashes into its prey, it puts stress on the hammers themselves. With all that stress, evolution gave the material a “Bouligand” shape. Instead of the material stacked on top of each other, it twists. Because of this process, rather than the mantis shrimp’s hammers cracking in half, they stay intact. This is where the inspiration came in for scientists.
Engineers at UCI and USC have invented a material based on those hammer-like appendages, a twist within a twist. They have 3D-printed a mantis shrimp-inspired Bouligand structure with the help of bacteria. Researchers printed a lattice structure, dipped it into a bacterial solution, and then after sitting for 12-24 hours secreted an enzyme called urease.
According to a WIRED article, “when researched dipped the structure into a second bath of urea and calcium ions, the urease kicked off a chemical reaction that created calcium carbonate. This is the same material that gives a clam’s shell – as well as your own bones and teeth – their strength. […] In the lab, as the researchers left the scaffolding in the solution, the calcium carbonate kept on accumulating, filling in the lattice entirely within 10 days, and giving researchers a super-tough material made of polymer skeleton and mineral innards.”
They were able to print lattices with shapes such as wave patterns and crosses. But what researchers really wanted was the Bouligand shape. When comparing different structures, the Bouligand shape absorbed 20x more energy than the others. The hope is to have these materials absorb energy like the mantis shrimp’s hammer. Another special aspect of this innovation is bacteria-built, so it can regenerate.
Researchers have high hopes for this Bouligand shape and its possibilities for many sectors!