Asters, bilayers and foams in coarse-grained model of active filament interactions

Microtubule-motor mixtures are a prime example of how living matter self-organizes into complex structures emerging from interactions between relatively simple constituents. Recently, experimental advances found a novel non-equilibrium phase of matter in these mixtures known as active foams [1], that consist of a network of bilayers experiencing continuous reconfiguration. We propose a microscopic model for motor-mediated filament-filament interactions and rigorously derive a continuum theory for the system. We discuss the phase diagram of our model, exhibiting asters, bilayers and active foams, and we inspect the mechanisms that drive the transition between these structures. Our work demonstrates the link between microscopic interactions and mesoscopic pattern formation in active filament systems and paves the way for higher-level theoretical studies on active foams.

[1] B. Lemma, N. P. Mitchell, R. Subramanian, D. J. Needleman, and Z. Dogic (2022). Active microphase separation in mixtures of microtubules and tip-accumulating molecular motors. Phys. Rev. X 12(3), 031006.