Dresden 2020 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Biomaterials and Biopolymers (joint session BP/CPP)

BP 7.3: Talk

Monday, March 16, 2020, 15:30–15:45, ZEU 250

Reversible Underwater Adhesion in Beetles — •Pranav Sudersan, Thomas Endlein, Michael Kappl, and Hans-Jürgen Butt — Max Planck Institute for Polymer Research, Mainz, Germany

Many animals are able to climb smooth surfaces using adhesive pads on their feet. Unlike artificial glues, animals can adhere reversibly i.e. attach and detach easily to a wide variety of surfaces. Insects such as beetles have hairy pads on their feet and also secrete an adhesive fluid resulting in capillary forces for strong attachment. In contrast to adhesion in air, reversible adhesion underwater is particularly challenging. Insects drawing their adhesive force from the capillary action of the air-fluid interface would not stick underwater as such an interface is usually abolished. Some terrestrial beetles are however able to easily adhere and walk underwater by using an entrapped air bubble around their hairy pads to de-wet the surface upon entering water. But it is unclear as to what extent the air bubble influences adhesion. In our study, we measure adhesion and friction forces in live ladybug beetles (Coccinella septempunctata) under controlled conditions. The effect of surface hydrophobicity, pad attachment/detachment speeds and de-wetted area on adhesion and friction performance is examined and compared for dry and wet surfaces. Our study aims to draw inspiration from an animal model in order to fabricate artificial adhesives which would work in a similar way.