Materials

Chiton-inspired body armor could both flex and protect

Chiton-inspired body armor cou...
A chiton's shell is flexible enough to let the animal conform to the contours of rocks, yet it hardens upon impact
A chiton's shell is flexible enough to let the animal conform to the contours of rocks, yet it hardens upon impact
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Samples of the material resisted penetration by broken glass
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Samples of the material resisted penetration by broken glass
A chiton's shell is flexible enough to let the animal conform to the contours of rocks, yet it hardens upon impact
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A chiton's shell is flexible enough to let the animal conform to the contours of rocks, yet it hardens upon impact
Development of the material involved first 3D-scanning actual chiton shells, and then performing tests with computer models
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Development of the material involved first 3D-scanning actual chiton shells, and then performing tests with computer models
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When it comes to body armor, there's typically a trade-off – it can either be highly impact-resistant or flexible, but not both. That may not be the case for much longer, however, thanks to an experimental new material inspired by a mollusc.

Ordinarily, the shells of molluscs either take the form of one rigid piece, or two hinged pieces (as is the case with clams). The chiton's oval shell is different, in that it's made up of eight overlapping plates, surrounded at the bottom by a ring-shaped "girdle." That girdle in turn consists of small, hard, overlapping scales, which are attached to softer underlying tissue.

This arrangement works well for the chiton. When external force is applied to the plates or scales, they converge inward and lock together, forming a hard, unyielding barrier. When the creature is trying to conform its body to the contours of the rocks that it clings to, though, the plates and scales slide back and forth against one another, keeping the shell flexible.

An international team of scientists recently set about replicating that functionality, ultimately producing a chiton-girdle-inspired material that is both flexible and impact-resistant. It consists of overlapping 3D-printed rigid "scales," mounted on a flexible substrate. In lab tests, those scales were found to form a solid barrier when subjected to outside mechanical force, yet to otherwise move with the substrate as it flexed.

Samples of the material resisted penetration by broken glass
Samples of the material resisted penetration by broken glass

It was also noted that the smaller the scales, the greater the flexibility and the lower the impact-resistance. This means that if body armor were to be made from the material, it would likely have smaller scales in bendy areas such as the knees and elbows, while incorporating larger plates in the torso.

"We wanted to integrate flexibility and protection, and that's very hard to achieve with synthetic systems," says Virginia Tech's Asst. Prof. Ling Li. "We will continue with our research to explore the design space beyond the original biological model system and conduct testing under different load conditions."

Also taking part in the study were scientists from MIT, Harvard University, California State University-Fullerton, and Germany's Max Planck Institute of Colloids and Interfaces. A paper on the research was recently published in the journal Nature Communications.

Previously, a team at MIT looked into developing chiton-inspired body armor with integrated optical systems.

Source: Virginia Tech

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2 comments
Ralf Biernacki
This principle has already been used in historic armor, in parts of medieval armor called the fauld, and most notably in the Roman lorica segmentata. As chitons are common in the Mediterranean, one wonders whether that's where the Romans got the idea. https://en.wikipedia.org/wiki/Lorica_segmentata
eMacPaul
They should try using chitin to make the scales, then they would have a chitin/chiton armor!