Mechanics of heterogeneous fiber networks

TL;DR

This study investigates how active stresses generated by microtubule-based fluids can irreversibly restructure actin-fascin networks, altering their mesoscale mechanics and viscoelastic properties.

Contribution

It introduces a combined active microrheology and fluorescence imaging method to analyze how active stresses reprogram fiber network structures and mechanics.

Findings

Increasing motor concentration broadens pore-size distribution.

Active processing extends displacement propagation range.

Networks soften and undergo plastic restructuring at large strains.

Abstract

Internally generated active stresses drive soft materials into architectures inaccessible to thermal self-assembly. We use a microtubule-based active fluid to assemble and irreversibly restructure actin-fascin networks. Subsequently, we probe the mesoscale mechanics of such networks by combining active microrheology with fluorescence imaging of the strain field around the probe. Increasing motor concentration broadens the pore-size distribution and thickens load-bearing bundles, raising the mean local elastic modulus and its spatial variability. Displacement fields of actively-processed networks propagate over longer range when compared to unprocessed networks. At large strains, both networks strain soften and plastically restructure. The combined microrheology and strain-imaging approach show that tunable active stresses reprogram the structure and viscoelastic response of fiber networks at the scale of their structural heterogeneity.