Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 17: Cell Mechanics I

BP 17.9: Vortrag

Mittwoch, 14. März 2018, 12:15–12:30, H 1058

Simultaneous measurement of the Young's modulus and the Poisson ratio of thin elastic layers — •Wolfgang Gross and Holger Kress — Department of Physics, University of Bayreuth, Bayreuth, Germany

The mechanical interplay between cells and their environment has become a major point of interest during the last decades. To quantify the interactions between cells and soft matrices with techniques such as traction force microscopy, precise knowledge of the elastic parameters of thin substrate layers is necessary. However, only few methods are available to simultaneously measure the elastic modulus and the Poisson ratio of thin substrate layers.

Here we describe a novel technique to measure both parameters in a single experiment. As a model system, we chose polyacrylamide and poly-N-Isopropylacrylamide layers with a thickness of 1/10th of a millimeter and a stiffness in the range of mammalian tissue. We place millimeter-sized steel spheres with different radii on the substrates which indent the surface due to gravity and visualize the indentation cap marked with fluorescent microparticles with an inverted microscope. Using a previously published model which takes finite thickness effects into account, we demonstrate experimentally for the first time that the model allows the simultaneous determination of both the elastic modulus and the Poisson ratio with high accuracy. Since the technique comes without the need of special equipment aside from an inverted microscope, we envision it to become a standard tool for the characterization of thin substrate layers.