Cut like ant teeth | Cutting tool engineering
Have you ever wondered how tiny creatures can so easily slice, puncture or poke? New research reveals that ants, worms, spiders and other tiny beings have a built-in set of tools that would be the envy of any carpenter or surgeon.
A study published in the scientific journal “Scientific Reports” shows for the first time how individual zinc atoms are arranged to maximize cutting efficiency and maintain sharpness in these exquisitely constructed animal tools. A collaboration between a research team from the University of Oregon and the US Department of Energy’s Pacific Northwest National Laboratory has revealed how tiny creatures cut and punch with relative ease.
Consider an ant’s tooth. Yes, ants have teeth, as anyone who has walked on an anthill can attest. These specialized structures — technically called mandibular teeth because they attach outside the mouth — are made up of a network of materials that tightly bind individual zinc atoms together. The effect is a mandible that contains more than 8% of the tooth’s weight with zinc.
These types of specialized creature tools have fascinated Associate Professor Robert Schofield, who led the study, for decades. His team of biophysicists has developed techniques to measure hardness, elasticity, fracture energy, abrasion resistance and impact resistance on a miniature scale.
But the team couldn’t see the structure of the materials that make up ant teeth and other microscopic animal tools, especially at the atomic scale. This is where PNNL materials scientist Arun Devaraj and PhD student Xiaoyue Wang came into the picture. Devaraj is an expert in using a specialized microscope technique called atom probe tomography. He used a focused ion beam microscope to take a small needle sample from the tip of an ant tooth, then imaged that needle sample using atom probe tomography, allowing the team to identify how individual atoms are arranged near the tip of an ant’s tooth.
Using this technique, Devaraj and Wang recorded for the first time the nanoscale distribution of zinc atoms in an ant’s tooth.
“We could see that the zinc is evenly distributed throughout the tooth, which was a surprise,” Devaraj said. “We expected the zinc to be clustered into nanonodules.”
The team estimated that because these biomaterials can be sharper, they allow animals to use 60% or even less of the force that would be needed if the tools were made of materials similar to those found in animals. human teeth. Because less force is needed, smaller muscles expend less energy. These benefits may explain why every spider, ant, worm, and crustacean, as well as many other organisms, have these specialized tools.
“Human engineers could also learn from this biological trick,” Schofield said. “The hardness of ant teeth, for example, increases from about the hardness of plastic to the hardness of aluminum when zinc is added. Although much harder engineering materials exist, they are often more fragile.
Devaraj said learning from nature is a way to understand what makes materials stronger and more resistant to damage. He uses a DOE Early Career Award to study these principles at the atomic scale.
“By studying the microstructure of steel also at the atomic scale,” he said, “we can better understand how changing the composition of materials changes its resistance to damage, in particular the resistance to corrosion under stress and its behavior over time.
— Karyn Hede