The tactile clubs of Mantis shrimp could keep secrets to more elastic surfaces for human use

University of California, Irvine materials scientists study science on resistance of mantis shrimp. The ancient crabs are armed with two hammered raptor attachments called dactyl clubs that they use to blow and strike their prey. These fists, which are capable of accelerating the body at more than 50 mph, deliver powerful blows, and then appear without damage.

The UCI researchers discovered that the clubs have a uniquely designed nanoparticle coating that absorbs and dissipates energy. The findings, published today in Natural materials, have important implications for engineered materials in the automotive, aerospace and sports industries.

“Remember to hit a wall a few thousand times at those speeds and not break your fist,” said David Kisailus, UCI professor of materials science and technology, who has been studying mantis shrimp for more than a decade. “That’s pretty impressive, and it got us thinking about how this could be.”

He and postdoctoral scientist Wei Huang use transmission electron and atomic force microscopy to examine the nanoscale architecture and material components of the club’s surface. They determine that the nanoparticles are two-continuous spheres, made of ultimately organic (protein and polysaccharide) and inorganic (calcium phosphate) nanocrystals.

The 3-D inorganic nanocrystals are mesocrystalline, essentially stacked together like Lego pieces, with small orientation differences where they coalesce. The crystalline interfaces are crucial for the resilience of the surface layer, as they break and break during impulse at high speed, thereby reducing the penetration depth by half.

“The high-resolution TEM really helped us to understand these particles, how they are architated and how they react under different types of stress,” Kisailus said. “At relatively low voltage figures, the particles deform almost like a marshmallow and recover when the voltage is released.”

He notes that the behavior of the structures under the influence of high penalties is much different. “The particles stiffen and break at the nanocrystalline interfaces,” Kisailus said. “When you break something, you open up new surfaces that dissipate significant amounts of energy.”

The team, led by researchers from Purdue University, Oxford Instruments and Bruker Corp. could also measure and characterize the impressive cushioning capabilities of the coating.

“The rigid inorganic and soft organic materials in an interpenetrating network impart impressive cushioning properties to the coating without compromising the stiffness. It is a rare combination that is superior to most metals and technical ceramics,” said Kisailus.

He added that he is now focused on translating these findings into new applications in a variety of fields: “We can imagine ways to construct similar particles to add improved protective surfaces for use in cars, aircraft, football helmets and body armor. ”