The humble oyster has been a talking point in biomimicry for years and earlier this year inspired research on creating stronger glass. Now nacre, the shell-material that protects the soft body of the oyster, is getting even more attention as a transparent material that in the future could even survive multiple gun-shots.
Oyster shell is 99% calcite, which is a soft material that has previously been used in magnifying gun sights. Unlike the calcite mines though, the oyster grows its calcite from the mantle creating wood-like ‘rings’ of growth. As Phys.Org reports:
The reason the material is up to 3,000 times tougher than the minerals it is made from is, counter-intuitively, because it is pre-cracked into a microscopic crystal structure. The fissures allow the material to bend and deform, while not transmitting the cracks further through the material. It’s all about absorbing the impact, like the crumple zone in a car.
The process of cracks forming, i.e. a material splitting into two parts, is called twinning. Ortiz’ new research focuses on ‘twinning’, the cracking of the crystals into two mirror images of each other. He cites this as the key process in dissipating energy quickly over a small space. The pre-existing cracks insulate the rest of the material from transmitting all of the energy of the impact, confining it to a local area though still allowing you to read through the (mostly) transparent substance.
Ortiz however highlights that further work is required before this product reaches market, though the work is still ongoing. As Live Science reports:
The logical conclusion of which is obviously that the modern use of firearms will become obsolete and we’ll see a renaissance of the art of hand to hand combat. Sci-fi knife fights anyone?