Beyond Dipolar Activity: Quadrupolar Stress Drives Collapse of Nematic Order on Frictional Substrates

Fuente: arXiv
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Main Authors: Ardaševa, Aleksandra, Vélez-Cerón, Ignasi, Pedersen, Martin Cramer, Ignés-Mullol, Jordi, Sagués, Francesc, Doostmohammadi, Amin
Format: Preprint
Published: 2024
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author Ardaševa, Aleksandra
Vélez-Cerón, Ignasi
Pedersen, Martin Cramer
Ignés-Mullol, Jordi
Sagués, Francesc
Doostmohammadi, Amin
author_facet Ardaševa, Aleksandra
Vélez-Cerón, Ignasi
Pedersen, Martin Cramer
Ignés-Mullol, Jordi
Sagués, Francesc
Doostmohammadi, Amin
contents The field of active nematics has traditionally employed descriptions based on dipolar activity, with interactions that align along a single axis. However, it has been theoretically predicted that interactions with a substrate, prevalent in most biological systems, would require novel forms of activity, such as quadrupolar activity, that are governed by hydrodynamic screening. Here, by combining experiments and numerical simulations, we show that upon light-induced solidification of the underlying medium, microtubule-kinesin mixtures undergo a transformation that leads to a biphasic active suspension. Using an active lyotropic model, we prove that the transition is governed by screening effects that alter the dominant form of active stress. Specifically, the combined effect of friction and quadrupolar activity leads to a hierarchical folding that follows the intrinsic bend instability of the active nematic layer. Our results demonstrate the dynamics of the collapse of orientational order in active nematics and present a new route for controlling active matter by modifying the activity through changing the surrounding environment.
format Preprint
id arxiv_https___arxiv_org_abs_2407_03723
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Beyond Dipolar Activity: Quadrupolar Stress Drives Collapse of Nematic Order on Frictional Substrates
Ardaševa, Aleksandra
Vélez-Cerón, Ignasi
Pedersen, Martin Cramer
Ignés-Mullol, Jordi
Sagués, Francesc
Doostmohammadi, Amin
Soft Condensed Matter
Biological Physics
The field of active nematics has traditionally employed descriptions based on dipolar activity, with interactions that align along a single axis. However, it has been theoretically predicted that interactions with a substrate, prevalent in most biological systems, would require novel forms of activity, such as quadrupolar activity, that are governed by hydrodynamic screening. Here, by combining experiments and numerical simulations, we show that upon light-induced solidification of the underlying medium, microtubule-kinesin mixtures undergo a transformation that leads to a biphasic active suspension. Using an active lyotropic model, we prove that the transition is governed by screening effects that alter the dominant form of active stress. Specifically, the combined effect of friction and quadrupolar activity leads to a hierarchical folding that follows the intrinsic bend instability of the active nematic layer. Our results demonstrate the dynamics of the collapse of orientational order in active nematics and present a new route for controlling active matter by modifying the activity through changing the surrounding environment.
title Beyond Dipolar Activity: Quadrupolar Stress Drives Collapse of Nematic Order on Frictional Substrates
topic Soft Condensed Matter
Biological Physics
url https://arxiv.org/abs/2407.03723