Effective diffusivity of microswimmers in a crowded environment

Abstract

The microalga Chlamydomonas Reinhardtii (CR) is used here as a model system to study the effect of complex environments on the swimming of micro-organisms. Its motion can be modelled by a run and tumble mechanism so that it describes a persistent random walk from which we can extract an effective diffusion coefficient for the large-time dynamics. In our experiments, the complex medium consists in a series of pillars that are designed in a regular lattice using soft lithography microfabrication. The cells are then introduced in the lattice, and their trajectories within the pillars are tracked and analyzed. The effect of the complex medium on the swimming behaviour of microswimmers is analyzed through the measure of relevant statistical observables. In particular, the mean correlation time of direction and the effective diffusion coefficient are shown to decrease when increasing the density of pillars. This provides some bases of understanding for active matter in complex environments.

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Cited by in corpus (13)

• Transport and dispersion of active particles in periodic porous media
• A fine balance of chemotactic and hydrodynamic torques: when microswimmers orbit a pillar just once
• Microscopic theory for the diffusion of an active particle in a crowded environment
• Mode-Coupling Theory for Tagged-Particle Motion of Active Brownian Particles
• Deflection of phototactic microswimmers through obstacle arrays
• Active Matter Invasion
• Random motion of a circle microswimmer in a random environment
• Stochastic force dynamics of the model microswimmer Chlamydomonas reinhardtii: Active forces and energetics
• Premelting controlled active matter in ice
• Behavioral transition of a fish school in a crowded environment
• 3D model for surface accumulation of chiral and non-chiral microswimmers
• Predator-prey plankton dynamics in turbulent wakes behind islands
• Self-organised structures in mixed active-passive suspensions due to hydrodynamic interactions