Shearing Living Liquid Crystals

ORAL

Abstract

Flagellated bacteria of pusher type, such as B. subtilis and E. coli, change the rheological properties of the surrounding isotropic medium. B. subtilis dispersed in a water-based lyotropic chromonic liquid crystals (LCLCs), form a “living liquid crystal” (LLC). Here, we explore the response of the LLC to shear, in particular, how the effective viscosity of LLC changes with the shear rate and how the flow-aligning effect of shear and liquid crystal-mediated elasticity compete with the activity of bacteria that destabilize the orientational order. Studies with an optical rheometer and polarizing optical microscope demonstrate that upon cessation of shear, the activity of bacteria leads to a progressive development of periodic director undulations (with the wave vector parallel to the shear direction), nucleation and multiplication of disclination pairs that produce the regime of topological turbulence. When the gap height increases, disclinations transform from short segments connecting opposite plates to elongated segments in the plane of the cell. The studies reveal a wealth of intriguing phenomena when the system transforms from 2D to 3D-like confinement.

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Presenters

  • Hend Baza

    Department of Physics and Advanced Materials Liquid Crystal Institute, Kent State University

Authors

  • Hend Baza

    Department of Physics and Advanced Materials Liquid Crystal Institute, Kent State University

  • Taras Turiv

    Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio, 44242, USA, Advanced Materials Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Advanced Materials and Liquid Crystal Institute, Kent State Univeristy, Kent State University, Advanced Materials and Liquid Crystal Institute, Chemical Physics Interdisciplinary Program, Kent State University

  • O D Lavrentovich

    Kent State University, Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio, 44242, USA, Department of Physics and Advanced Materials Liquid Crystal Institute, Kent State University, Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program and Physics Department, Kent State University, Advanced Materials and Liquid Crystal Institute, Kent State Univeristy, Advanced Materials and Liquid Crystal Institute / Department of Physics, Kent State University, Kent, OH 44242, USA, Department of Physics, Advanced Materials and Liquid Crystal Institute, Chemical Physics Interdisciplinary Program, Kent State University

  • Antal Istvan Jakli

    Liquid Crystal Institute, Kent State University, Department of Physics and Advanced Materials Liquid Crystal Institute, Kent State University, Chemical Physics Interdisciplinary Program, Liquid Crystal Institute, Kent State University, Kent, OH USA, Chemical Physics Interdisciplinary Program, Kent State University, Advanced Materials & Liquid Crystal Institute, Kent State University, Kent State University, Department of Physics, Kent State University,Kent, OH 44240, USA