Emergent probability fluxes in confined microbial navigation

Area of Science:

• Microbial motility
• Active matter physics
• Complex systems

Background:

• Cellular motion appears erratic but can exhibit organization under nonequilibrium conditions.
• Current understanding of self-organization in active systems is limited to bulk or idealized geometries.
• The emergence of self-organization in complex geometries and at specific length scales remains poorly understood.

Purpose of the Study:

• To investigate how self-organization emerges in the motion of motile cells within complex microfluidic geometries.
• To determine the role of boundary curvature in organizing active cellular motion.
• To establish a link between nonequilibrium probability fluxes and global geometric properties.

Main Methods:

• Controlled microfluidic experiments to observe single-cell motion.
• Analytical calculations to model active motion and interfacial forces.
• Numerical simulations to explore self-organization in nontrivial geometries.

Main Results:

• Probability flux loops were identified as organizing principles for active motion, even at the single-cell level.
• The curvature of the boundary was found to directly influence nonequilibrium probability fluxes.
• A universal relationship between probability fluxes and global geometric properties was theoretically predicted and experimentally validated.

Conclusions:

• Self-organization in active cellular motion is achievable in complex geometries through probability flux loops.
• Boundary curvature is a critical factor in determining the direction and organization of cell movement.
• The findings enable prediction of probable cell trajectories and design of geometries for directed motion.