Shear thickening and Yielding Transitions in Biological Tissues #

Michael Hertaeg, Suzanne Fielding, Dapeng Bi

15:10 Monday in 2Q48.

Part of the Controlling active matter session.

Abstract #

During key processes such as wound healing, morphogenesis and cancer metastasis, biological tissues display phenomena resembling those associated with the glass or jamming transition. Such transitions have been well studied in non-biological particulate systems, in which the packing fraction is a key control parameter. However, liquid-solid transitions occur in confluent biological tissues, demonstrating a fundamentally different mechanism. Previous experimental and theoretical work has identified several key factors that determine tissue fluidity or rigidity. These include cell shape, which is determined by a competition between cell-cell adhesion and cortical tension. Many cells furthermore produce active forces through swimming or crawling, which were also found to influence rigidity.

In this work, we study numerically the non-linear rheology of biological tissues using a minimal vertex-based model, in which a 2D layer of active confluent cells is represented by a tiling of polygons, defined by the positions of the vertices [1] . The interaction between strain rate, cell shape and activity are identified and new mechanisms responsible for observed tissue behaviour are proposed. We find the competition between globally external and locally internal active driving produces a range of distinct rheological behaviours, including yielding, shear thinning, continuous shear thickening, and discontinuous shear thickening [2].

[1] R. Farhadifar, et al., Current Biology. 17, 24, (2007)

[2] M. Hertaeg, et al., arXive. https://arxiv.org/abs/2211.15015, (2022).