Beetle exoskeleton secrets could yield clues to low drag in vehicles and airplanes

Cotinis mutabilis Beetle

Scientists have been studying the structure and properties of beetle exoskeletons at the nanoscale, findings of which could pave way for much lighter and strong materials that could help us reduce drag in vehicles and airplanes and reduce the weight of armor.

Until now study of beetle exoskeletons at the nanoscale has been a challenge, but scientists at University of Nebraska-Lincoln have found a way to analyze the fibrous nanostructure. According to the team involved with the study, beetle’s lightweight exoskeleton is composed of chitin fibers just around 20 nanometers in diameter. In comparison, a human hair measures approximately 75,000 nanometers in diameter.

These fibers are packed and piled into layers that twist in a spiral, like a spiral staircase. The small diameter and helical twisting, known as Bouligand, make the structure difficult to analyze.

The team developed a method of slicing down the spiral to reveal a surface of cross-sections of fibers at different orientations. From that viewpoint, the researchers were able to analyze the fibers’ mechanical properties with the aid of an atomic force microscope. This type of microscope applies a tiny force to a test sample, deforms the sample and monitors the sample’s response. Combining the experimental procedure and theoretical analysis, the researchers were able to reveal the nanoscale architecture of the exoskeleton and the material properties of the nanofibers.

While the discoveries have been made through the study of common figeater beetle, Cotinis mutabilis, which is a metallic green native of the western United States, scientists say that their technique can be used on other beetles and hard-shelled creatures and might also extend to artificial materials with fibrous structures, Yang said.

Comparing beetles with differing demands on their exoskeletons, such as defending against predators or environmental damage, could lead to evolutionary insights as well as a better understanding of the relationship between structural features and their properties.

The study has been published in Advanced Functional Materials.