Beyond Dipolar Activity: Quadrupolar Stress Drives Collapse of Nematic Order on Frictional Substrates
Year: 2025
Type: article
Abstract: The field of active nematics has traditionally employed descriptions based on dipolar activity. However, it is theoretically predicted that interactions with a substrate, prevalent in most biological systems, lead to novel forms of activity, such as quadrupolar activity, that are governed by hydrodynamic screening. Here, 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.
Source: Physical Review Letters
Institutions: University of Copenhagen, Universitat de Barcelona
Language: English
Topic: Micro and Nano Robotics
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, Brandeis University, Villum Fonden, Brainerd Foundation, European Commission, Generalitat de Catalunya, Novo Nordisk, Universitat de Barcelona, Novo Nordisk Fonden, Materials Research Science and Engineering Center, Harvard University, HORIZON EUROPE Framework Programme, Agencia Estatal de Investigación, Division of Materials Research, H2020 European Research Council, HORIZON EUROPE Marie Sklodowska-Curie Actions
Awards: G1175115578, G131914215, G202028452, G2064873908, G2170370641, G2262748287, Bioinspired Soft Materials, G2462415295, G2550080368, G2601397997, G294895050, G3005324705, G300979063, G3480869486, G3524997250, G3546882995, G3681454997, G4042783231, G4104517225, G425668148, G4945238505, G5080475149, G5195188938, G5241811275, G526284697, G7084143925, G726417499, Topography-Mediated Cell Communication, G7805188513, G7833242660, G787121397, G8059130316, G8088400230
OpenAlex ID: W4407956672