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BP: Fachverband Biologische Physik

BP 15: Poster IIb

BP 15.22: Poster

Tuesday, March 19, 2024, 18:00–20:30, Poster F

Rate-independent hysteretic energy dissipation in collagen fibrils — •Martin Dehnert, Paul Zech, Alexandra Bendixen, Andreas Otto, and Robert Magerle — Fakultät für Naturwissenschaften, Technische Universität Chemnitz, Germany

Nanoindentation cycles measured with an atomic force microscope on hydrated collagen fibrils exhibit a rate-independent hysteresis with return point memory. This previously unknown energy dissipation mechanism describes in unified form elastoplastic indentation, capillary adhesion, and surface leveling at indentation velocities smaller than 1  µm/s, where viscous friction is negligible. A generic hysteresis model, based on force–distance (FD) data measured during one large approach-retract cycle, predicts the force (output) and the dissipated energy for arbitrary indentation trajectories (input). While both quantities are rate-independent, they do depend nonlinearly on the indentation history and on the indentation amplitude. We present different types of cyclic FD measurements performed on native collagen fibrils in humid air. The energy dissipation is mainly caused by plastic deformation during tip indentation and it can be quantified with the plasticity index. The latter can be used for high-resolution mapping of connective tissues.

Keywords: Collagen; Nanomechanics; Hysteresis; Atomic Force Microscopy; Force-Distance Data