Hunting spiders easily climb vertical surfaces or move upside down on the ceiling. A thousand tiny hairs at the ends of their legs make sure they do not fall off. Like the spider’s exoskeleton, these bristle-like hairs (so-called setae) mainly consist of proteins and chitin, which is a polysaccharide.
To find out more about their fine structure, an interdisciplinary research team from the Biology and Physics departments at Kiel University and the Helmholtz-Zentrum Geesthacht (HZG) examined the molecular structure of these hairs in closer detail. Using highly energetic X-ray light, the researchers discovered that the chitin molecules of the setae are specifically arranged to withstand the stresses of constant attachment and detachment.
Their findings could be the basis for highly resilient future materials. They have been published in the current issue of the Journal of the Royal Society Interface (“Hierarchical architecture of spider attachment setae reconstructed from scanning nanofocus X-ray diffraction data.”).

The tiny contact plates on the spider legs, which are only a few hundred nanometres in size, are subject to great forces when the spider is running or climbing. However, these adhesive structures easily withstand the heavy strain.

“In comparison, artificially produced materials tend to break more often,” says Professor Stanislav N. Gorb from the Zoological Institute at Kiel University. “That’s why we want to find out what makes spider legs so stable in resisting strong pull off forces.”

Together with the members of his “Functional Morphology and Biomechanics” working group, the zoologist investigates mechanisms of biological adhesion and how they could be transferred in artificial materials and surfaces.

Gorb and his colleague, the zoologist and biomechanist Dr Clemens Schaber, assumed that the secret behind the stability of spider adhesive hairs lies in the molecular structure of their material. Given the hairs’ small dimensions in the lower micrometre range, however, it is impossible to investigate their molecular material architecture using conventional methods.

Image Credit:  Cheetah 100

Read more at nanowerk.com

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