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Updated: Dec 8, 2025
08:37
Forming, Confining, and Observing Microtubule-Based Active Nematics
Published on: January 13, 2023
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Driven topological transitions in active nematic films
David P Rivas1, Tyler N Shendruk2, Robert R Henry1
1Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA. leheny@jhu.edu.
Soft Matter
|September 16, 2020
Summary
Active nematic films exhibit controllable topological defects. Applying stress can merge +1/2 defects into +1 vortices, altering flow dynamics and revealing anomalous viscoelasticity.
Area of Science:
- Soft Matter Physics
- Active Matter Physics
- Topological Defects
Background:
- Topological properties are crucial for material behavior, especially in active materials far from equilibrium.
- The dynamics of topological defects significantly influence the properties of active materials.
Purpose of the Study:
- To demonstrate local manipulation of order, dynamics, and topological properties in microtubule-based active nematic films.
- To investigate the influence of external stresses on topological defect behavior and active film hydrodynamics.
Main Methods:
- Joint experimental and simulation study using microtubule-based active nematic films.
- Magnetic actuation of disk-shaped colloids to create localized hydrodynamic stresses.
- Lattice Boltzmann simulations to model film behavior and capture anomalous viscoelasticity.
Main Results:
- Applied stresses influence the motion of +1/2 charge topological defects.
- Sufficient stress drives the merger of two +1/2 defects into a +1 charge topological vortex.
- Defect motion leads to ordering of vorticity and velocity, unlike passive films.
- Topological vortex formation is linked to a rheological instability and increased flow velocities.
Conclusions:
- Local stress application provides control over topological defects and dynamics in active nematics.
- The study reveals the anomalous viscoelastic nature of active nematic films.
- Lattice Boltzmann simulations effectively capture key features of the active nematic response to stress.
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