Engineering
The Role of Negative Poisson's Ratio Metamaterials in Impact Protection
Quick fact
Some impact-protective foams are made from auxetic metamaterials: when compressed, they get denser and harder at the impact point, absorbing more energy than conventional foams of the same weight.
Why this is interesting
Imagine a rubber band that thickens when you stretch it—that's a material with a negative Poisson's ratio. How could such a weird behavior make your helmet safer?