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BP: Fachverband Biologische Physik

BP 24: Poster B: Active Biological Matter, Cell Mechanics, Systems Biology, Computational Biophysics, etc.

BP 24.16: Poster

Tuesday, March 23, 2021, 16:00–18:30, BPp

3D direct and inverse traction force microscopy — •Johannes Wolfram Blumberg and Ulrich Sebastian Schwarz — Institute for Theoretical Physics and BioQuant, Heidelberg University

In traction force microscopy (TFM), the mechanical forces of cells adhering to an elastic substrate are estimated from the substrate displacements as measured by the movement of embedded fiducial marker beads. Usually, this estimate is obtained by minimizing the mean squared distance between experimentally observed and predicted displacements (inverse TFM). In direct TFM, in contrast, the stress tensor and the surface tractions are calculated directly and locally from the deformation field using the underlying material law. This procedure makes it easier to estimate not only tangential, but also normal forces, and to deal with non-planar substrates, but it is also more sensitive to noise. In general, it is not clear how well direct TFM performs compared with inverse TFM. We have compared the direct method for TFM to the standard inverse method, which is Fourier transformed traction cytometry (FTTC). In particular, we developed a method to estimating the local inaccuracy based on the divergence-freeness of the stress tensor. We discuss the relative strengths and weakness of the two methods and find that each of them can be preferable for certain settings.