The wings of Megatibicen dorsatus, a prairie-dwelling cicada, are helping engineers design water-repellent surfaces. Credit: Photo courtesy Catherine Dana
Researchers are looking to insects – specifically cicadas – for insight into the design of artificial surfaces with de-icing, self-cleaning and anti-fogging abilities.Their wings allow cicadas to fly, of course, but they also are good at repelling water – a condition that humans can appreciate, too. “Our work with cicadas is letting us explore a field called bioinspiration,” said Nenad Miljkovic, a University of Illinois mechanical science and engineering professor who co-led a new study of cicada wings.
“We are learning as much as we can from the natural design of cicada wings to engineer artificial objects that are useful to humans.” The study focused on the water-repelling ability of cicada wings. The research team of engineers and entomologists used high-speed microscopic photography to study the wings’ ability to repel water. “The property that allows a surface to repel water is called hydrophobicity and it causes water to bead up and roll away,” Miljkovic said. “Superhydrophobicity is simply an extreme form of this property and cicada wings that have this feature have a rough nanotexture that creates open spaces around water droplets, allowing surface tension to force the droplets to jump off of the wings.”
“Traditionally, the idea would be to collect cicadas that live in wetlands to study wing hydrophobicity,” said Marianne Alleyne, an entomology research scientist. Such studies are based on the assumption that wetland-dwelling cicadas have the most water-repellant wings. “We wanted to test this hypothesis, so we collected four different species – one found in wetlands, one from forests, one from prairie lands – all annual cicadas – and one periodic seventeen-year cicada,” Alleyne said.
“We expected to find that the specimens from drier habitats would lack superhydrophobicity,” said Catherine Dana, an entomology graduate student. “We were surprised to find the opposite, and that habitat is not a good predictor of this extreme water-repelling ability of the cicada wings.” It turns out that other factors may be better predictors of superhydrophobicity, such as differences in species life cycles — annual versus perennial varieties, for example – and species relatedness.
https://news.illinois.edu/blog/view/6367/537912
Video: https://www.youtube.com/watch?v=dEyQ64AqtZk
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