Regensburg 2025 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Poster Session II

BP 17.27: Poster

Tuesday, March 18, 2025, 18:00–20:30, P4

Thermal and directional motion of trapped particles in periodic potentials — •Ellen Hermle and Alexander Rohrbach — Lab for Bio- and Nano-Photonics, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany

Molecular fiction can be considered as continuous on-binding and off-binding of molecules between two sliding surfaces. This complex process of energy dissipation to the environment, is important on most length scales, time scales and across disciplines. Usually, the relation between dynamic friction and velocity is quantified by a coefficient, which depends on various on- and off-binding parameters. Here, optical tweezers based Photonic Force Microscopy (PFM) has proven to be a suitable technique is used to analyse friction processes on mesoscopic length scales, specially at soft (-bio) interfaces. By 3D interferometric position tracking at 1 MHz we determine mean particle displacements and forces, as well as fluctuations of displacements and forces. Besides Brownian dynamic simulations, we present first experimental results of fluctuating particles dragged through a periodic potential, which can be generated by an optical potential from two interfering beams or by a specifically coated glass surface.

Keywords: friction; optical trapping; interferometric tracking; particle diffusion