Pinned Boundaries Delay Contraction and Shape Stress Relaxation in Active Gels
Researchers studying reconstituted actomyosin gels found that when the material is anchored to opposing surfaces (mimicking cellular constraints in tissues), contraction is delayed and stress builds up before being released through multiple pathways. The study combines experimental observations with a hydrodynamic model to explain how boundary conditions affect stress dynamics in contractile materials. These findings could improve understanding of cellular mechanics and inform the design of adaptive soft materials and bioinspired systems.
Scientists investigated how mechanical constraints affect the contraction dynamics of actomyosin gels—materials that mimic the contractile machinery in cells. Using reconstituted gels pinned to two opposing surfaces, they observed that boundary adhesion causes stress accumulation, intermittent contraction patterns, and nonuniform strain distribution, contrasting with freely contracting systems studied previously. Stress is relieved through multiple mechanisms including symmetric constriction and defect-driven processes like boundary detachment and internal rupture. The researchers developed a hydrodynamic model incorporating elastic, viscous, and active stress components that successfully predicts distinct energy relaxation rates before and after detachment events. Numerical simulations corroborated experimental observations and revealed how internal energy is generated and dissipated during stress cycles. The work demonstrates that spatial heterogeneity and boundary conditions fundamentally govern mechanical behavior in contractile active materials.
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- arXiv physicsCenter
Pinned Boundaries Delay Contraction and Shape Stress Relaxation in Active Gels
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