1
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Sinha A, Chaudhuri D. Activity-induced phase transition and coarsening dynamics in dry apolar active nematics. SOFT MATTER 2024. [PMID: 39355944 DOI: 10.1039/d4sm00775a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2024]
Abstract
Using the Lebwohl-Lasher interaction for reciprocal local alignment, we present a comprehensive phase diagram for a dry, apolar, active nematic system using its stochastic off-lattice dynamics. The nematic-isotropic transition in this system is first-order and occurs alongside a fluctuation-dominated phase separation. Our phase diagram identifies three distinct regions based on activity and orientational noise relative to alignment strength: a homogeneous isotropic phase, a nematic phase with giant density fluctuations, and a coexistence region. Using mean-field analysis and hydrodynamic theory, we demonstrate that reciprocal interactions lead to a density fluctuation-induced first-order transition and derive a phase boundary consistent with numerical results. Quenching from the isotropic to nematic phase reveals coarsening dynamics where nematic ordering precedes particle clustering. Both the nematic and density fields exhibit similar scaling behaviors, exhibiting dynamic exponents zS ≈ 2.5 and zρ ≈ 2.34, consistently falling within the range of 2 and 3.
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Affiliation(s)
- Arpan Sinha
- Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Debasish Chaudhuri
- Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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2
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Adar RM, Joanny JF. Environment-Stored Memory in Active Nematics and Extra-Cellular Matrix Remodeling. PHYSICAL REVIEW LETTERS 2024; 133:118402. [PMID: 39331992 DOI: 10.1103/physrevlett.133.118402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 08/12/2024] [Indexed: 09/29/2024]
Abstract
Many active systems display nematic order, while interacting with their environment. In this Letter, we show theoretically how environment-stored memory acts an effective external field that aligns active nematics. The coupling to the environment leads to substantial modifications of the known phase diagram and dynamics of active nematics, including nematic order at arbitrarily low densities and arrested domain coarsening. We are motivated mainly by cells that remodel fibers in their extra-cellular matrix (ECM), while being directed by the fibers during migration. Our predictions indicate that remodeling promotes cellular and ECM alignment, and possibly limits the range of ordered ECM domains, in accordance with recent experiments.
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Affiliation(s)
| | - Jean-François Joanny
- Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France
- Laboratoire Physico-Chimie Curie, Institut Curie, Centre de Recherche, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, 75005 Paris, France
- Université Pierre et Marie Curie, Sorbonne Universités, 75248 Paris, France
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3
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Anderson C, Fernandez-Nieves A. Active many-particle systems and the emergent behavior of dense ant collectives. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:066602. [PMID: 38804124 DOI: 10.1088/1361-6633/ad49b4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 05/10/2024] [Indexed: 05/29/2024]
Abstract
This article discusses recent work with fire ants,Solenopisis invicta, to illustrate the use of the framework of active matter as a base to rationalize their complex collective behavior. We review much of the work that physicists have done on the group dynamics of these ants, and compare their behavior to two minimal models of active matter, and to the behavior of the synthetic systems that have served to test and drive these models.
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Affiliation(s)
- C Anderson
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
| | - A Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
- Institute for Complex Systems (UBICS), University of Barcelona, 08028 Barcelona, Spain
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4
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Spera G, Duclut C, Durand M, Tailleur J. Nematic Torques in Scalar Active Matter: When Fluctuations Favor Polar Order and Persistence. PHYSICAL REVIEW LETTERS 2024; 132:078301. [PMID: 38427854 DOI: 10.1103/physrevlett.132.078301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/12/2023] [Accepted: 01/08/2024] [Indexed: 03/03/2024]
Abstract
We study the impact of nematic alignment on scalar active matter in the disordered phase. We show that nematic torques control the emergent physics of particles interacting via pairwise forces and can either induce or prevent phase separation. The underlying mechanism is a fluctuation-induced renormalization of the mass of the polar field that generically arises from nematic torques. The correlations between the fluctuations of the polar and nematic fields indeed conspire to increase the particle persistence length, contrary to what phenomenological computations predict. This effect is generic and our theory also quantitatively accounts for how nematic torques enhance particle accumulation along confining boundaries and opposes demixing in mixtures of active and passive particles.
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Affiliation(s)
- Gianmarco Spera
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
| | - Charlie Duclut
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
- Laboratoire Physique des Cellules et Cancer (PCC), CNRS UMR 168, Institut Curie, Université PSL, Sorbonne Université, 75005 Paris, France
| | - Marc Durand
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
| | - Julien Tailleur
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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5
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Sinha A, Chaudhuri D. How reciprocity impacts ordering and phase separation in active nematics? SOFT MATTER 2024; 20:788-795. [PMID: 38165880 DOI: 10.1039/d3sm00795b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Active nematics undergo spontaneous symmetry breaking and show phase separation instability. Within the prevailing notion that macroscopic properties depend only on symmetries and conservation laws, different microscopic models are used out of convenience. Here, we test this notion carefully by analyzing three different microscopic models of apolar active nematics. They share the same symmetry but differ in implementing reciprocal or non-reciprocal interactions, including a Vicsek-like implementation. We show how such subtle differences in microscopic realization determine if the ordering transition is continuous or first order. Despite the difference in the type of phase transition, all three models exhibit fluctuation-dominated phase separation and quasi-long-range order in the nematic phase.
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Affiliation(s)
- Arpan Sinha
- Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
- Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Debasish Chaudhuri
- Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
- Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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6
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Krüger T, Maryshev I, Frey E. Hierarchical defect-induced condensation in active nematics. SOFT MATTER 2023; 19:8954-8964. [PMID: 37971530 DOI: 10.1039/d3sm00895a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Topological defects play a central role in the formation and organization of various biological systems. Historically, such nonequilibrium defects have been mainly studied in the context of homogeneous active nematics. Phase-separated systems, in turn, are known to form dense and dynamic nematic bands, but typically lack topological defects. In this paper, we use agent-based simulations of weakly aligning, self-propelled polymers and demonstrate that contrary to the existing paradigm phase-separated active nematics form -1/2 defects. Moreover, these defects, emerging due to interactions among dense nematic bands, constitute a novel second-order collective state. We investigate the morphology of defects in detail and find that their cores correspond to a strong increase in density, associated with a condensation of nematic fluxes. Unlike their analogs in homogeneous systems, such condensed defects form and decay in a different way and do not involve positively charged partners. We additionally observe and characterize lateral arc-like structures that separate from a band's bulk and move in transverse direction. We show that the key control parameters defining the route from stable bands to the coexistence of dynamic lanes and defects are the total density of particles and their path persistence length. We introduce a hydrodynamic theory that qualitatively recapitulates all the main features of the agent-based model, and use it to show that the emergence of both defects and arcs can be attributed to the same anisotropic active fluxes. Finally, we present a way to artificially engineer and position defects, and speculate about experimental verification of the provided model.
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Affiliation(s)
- Timo Krüger
- Arnold Sommerfeld Center for Theoretical Physics (ASC) and Center for NanoScience (CeNS), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstrasse 37, 80333 Munich, Germany.
| | - Ivan Maryshev
- Arnold Sommerfeld Center for Theoretical Physics (ASC) and Center for NanoScience (CeNS), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstrasse 37, 80333 Munich, Germany.
| | - Erwin Frey
- Arnold Sommerfeld Center for Theoretical Physics (ASC) and Center for NanoScience (CeNS), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstrasse 37, 80333 Munich, Germany.
- Max Planck School Matter to Life, Hofgartenstraße 8, 80539 Munich, Germany
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7
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Meyer H, Rieger H. Alignment interaction and band formation in assemblies of autochemorepulsive walkers. Phys Rev E 2023; 108:034604. [PMID: 37849087 DOI: 10.1103/physreve.108.034604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 08/18/2023] [Indexed: 10/19/2023]
Abstract
Chemotaxis refers to the motion of an organism induced by chemical stimuli and is a motility mode shared by many living species that has been developed by evolution to optimize certain biological processes such as foraging or immune response. In particular, autochemotaxis refers to chemotaxis mediated by a cue produced by the chemotactic particle itself. Here, we investigate the collective behavior of autochemotactic particles that are repelled by the cue and therefore migrate preferentially towards low-concentration regions. To this end, we introduce a lattice model inspired by the true self-avoiding walk which reduces to the Keller-Segel model in the continuous limit, for which we describe the rich phase behavior. We first rationalize the chemically mediated alignment interaction between walkers in the limit of stationary concentration fields, and then describe the various large-scale structures that can spontaneously form and the conditions for them to emerge, among which we find stable bands traveling at constant speed in the direction transverse to the band.
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Affiliation(s)
- Hugues Meyer
- Department of Theoretical Physics & Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany
| | - Heiko Rieger
- Department of Theoretical Physics & Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
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8
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Luo Y, Gu M, Park M, Fang X, Kwon Y, Urueña JM, Read de Alaniz J, Helgeson ME, Marchetti CM, Valentine MT. Molecular-scale substrate anisotropy, crowding and division drive collective behaviours in cell monolayers. J R Soc Interface 2023; 20:20230160. [PMID: 37403487 PMCID: PMC10320338 DOI: 10.1098/rsif.2023.0160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/13/2023] [Indexed: 07/06/2023] Open
Abstract
The ability of cells to reorganize in response to external stimuli is important in areas ranging from morphogenesis to tissue engineering. While nematic order is common in biological tissues, it typically only extends to small regions of cells interacting via steric repulsion. On isotropic substrates, elongated cells can co-align due to steric effects, forming ordered but randomly oriented finite-size domains. However, we have discovered that flat substrates with nematic order can induce global nematic alignment of dense, spindle-like cells, thereby influencing cell organization and collective motion and driving alignment on the scale of the entire tissue. Remarkably, single cells are not sensitive to the substrate's anisotropy. Rather, the emergence of global nematic order is a collective phenomenon that requires both steric effects and molecular-scale anisotropy of the substrate. To quantify the rich set of behaviours afforded by this system, we analyse velocity, positional and orientational correlations for several thousand cells over days. The establishment of global order is facilitated by enhanced cell division along the substrate's nematic axis, and associated extensile stresses that restructure the cells' actomyosin networks. Our work provides a new understanding of the dynamics of cellular remodelling and organization among weakly interacting cells.
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Affiliation(s)
- Yimin Luo
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Mengyang Gu
- Department of Statistics and Applied Probability, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Minwook Park
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Xinyi Fang
- Department of Statistics and Applied Probability, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Younghoon Kwon
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Juan Manuel Urueña
- BioPACIFIC MIP, California NanoSystems Institute, Santa Barbara, CA 93106, USA
| | - Javier Read de Alaniz
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Matthew E. Helgeson
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Cristina M. Marchetti
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Megan T. Valentine
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
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9
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Joshi C, Ray S, Lemma LM, Varghese M, Sharp G, Dogic Z, Baskaran A, Hagan MF. Data-Driven Discovery of Active Nematic Hydrodynamics. PHYSICAL REVIEW LETTERS 2022; 129:258001. [PMID: 36608242 DOI: 10.1103/physrevlett.129.258001] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
Active nematics can be modeled using phenomenological continuum theories that account for the dynamics of the nematic director and fluid velocity through partial differential equations (PDEs). While these models provide a statistical description of the experiments, the relevant terms in the PDEs and their parameters are usually identified indirectly. We adapt a recently developed method to automatically identify optimal continuum models for active nematics directly from spatiotemporal data, via sparse regression of the coarse-grained fields onto generic low order PDEs. After extensive benchmarking, we apply the method to experiments with microtubule-based active nematics, finding a surprisingly minimal description of the system. Our approach can be generalized to gain insights into active gels, microswimmers, and diverse other experimental active matter systems.
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Affiliation(s)
- Chaitanya Joshi
- Department of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
- Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155, USA
| | - Sattvic Ray
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Linnea M Lemma
- Department of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Minu Varghese
- Department of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 USA
| | - Graham Sharp
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Zvonimir Dogic
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Aparna Baskaran
- Department of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Michael F Hagan
- Department of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
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10
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Aranson IS. Bacterial active matter. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 85:076601. [PMID: 35605446 DOI: 10.1088/1361-6633/ac723d] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
Bacteria are among the oldest and most abundant species on Earth. Bacteria successfully colonize diverse habitats and play a significant role in the oxygen, carbon, and nitrogen cycles. They also form human and animal microbiota and may become sources of pathogens and a cause of many infectious diseases. Suspensions of motile bacteria constitute one of the most studied examples of active matter: a broad class of non-equilibrium systems converting energy from the environment (e.g., chemical energy of the nutrient) into mechanical motion. Concentrated bacterial suspensions, often termed active fluids, exhibit complex collective behavior, such as large-scale turbulent-like motion (so-called bacterial turbulence) and swarming. The activity of bacteria also affects the effective viscosity and diffusivity of the suspension. This work reports on the progress in bacterial active matter from the physics viewpoint. It covers the key experimental results, provides a critical assessment of major theoretical approaches, and addresses the effects of visco-elasticity, liquid crystallinity, and external confinement on collective behavior in bacterial suspensions.
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Affiliation(s)
- Igor S Aranson
- Departments of Biomedical Engineering, Chemistry, and Mathematics, Pennsylvania State University, University Park, PA 16802, United States of America
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11
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Liu Z, Zeng W, Ma X, Cheng X. Density fluctuations and energy spectra of 3D bacterial suspensions. SOFT MATTER 2021; 17:10806-10817. [PMID: 34787630 DOI: 10.1039/d1sm01183a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Giant number fluctuations are often considered as a hallmark of the emergent nonequilibrium dynamics of active fluids. However, these anomalous density fluctuations have only been reported experimentally in two-dimensional dry active systems heretofore. Here, we investigate density fluctuations of bulk Escherichia coli suspensions, a paradigm of three-dimensional (3D) wet active fluids. Our experiments demonstrate the existence and quantify the scaling relation of giant number fluctuations in 3D bacterial suspensions. Surprisingly, the anomalous scaling persists at small scales in low-concentration suspensions well before the transition to active turbulence, reflecting the long-range nature of hydrodynamic interactions of 3D wet active fluids. To illustrate the origin of the density fluctuations, we measure the energy spectra of suspension flows and explore the density-energy coupling in both the steady and transient states of active turbulence. A scale-invariant density-independent correlation between density fluctuations and energy spectra is uncovered across a wide range of length scales. In addition, our experiments show that the energy spectra of bacterial turbulence exhibit the scaling of 3D active nematic fluids, challenging the common view of dense bacterial suspensions as active polar fluids.
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Affiliation(s)
- Zhengyang Liu
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Wei Zeng
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
- College of Life Science and Technology, Guangxi University, Nanning 530004, Guangxi, China
| | - Xiaolei Ma
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Xiang Cheng
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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12
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Peterson MSE, Baskaran A, Hagan MF. Vesicle shape transformations driven by confined active filaments. Nat Commun 2021; 12:7247. [PMID: 34903731 PMCID: PMC8668962 DOI: 10.1038/s41467-021-27310-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 11/12/2021] [Indexed: 12/02/2022] Open
Abstract
In active matter systems, deformable boundaries provide a mechanism to organize internal active stresses. To study a minimal model of such a system, we perform particle-based simulations of an elastic vesicle containing a collection of polar active filaments. The interplay between the active stress organization due to interparticle interactions and that due to the deformability of the confinement leads to a variety of filament spatiotemporal organizations that have not been observed in bulk systems or under rigid confinement, including highly-aligned rings and caps. In turn, these filament assemblies drive dramatic and tunable transformations of the vesicle shape and its dynamics. We present simple scaling models that reveal the mechanisms underlying these emergent behaviors and yield design principles for engineering active materials with targeted shape dynamics.
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Affiliation(s)
- Matthew S E Peterson
- Martin A. Fisher School of Physics, Brandeis University, Waltham, MA, 02453, United States
| | - Aparna Baskaran
- Martin A. Fisher School of Physics, Brandeis University, Waltham, MA, 02453, United States.
| | - Michael F Hagan
- Martin A. Fisher School of Physics, Brandeis University, Waltham, MA, 02453, United States.
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13
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Ventejou B, Chaté H, Montagne R, Shi XQ. Susceptibility of Orientationally Ordered Active Matter to Chirality Disorder. PHYSICAL REVIEW LETTERS 2021; 127:238001. [PMID: 34936788 DOI: 10.1103/physrevlett.127.238001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 10/27/2021] [Indexed: 06/14/2023]
Abstract
We investigate the susceptibility of long-range ordered phases of two-dimensional dry aligning active matter to population disorder, taken in the form of a distribution of intrinsic individual chiralities. Using a combination of particle-level models and hydrodynamic theories derived from them, we show that while in finite systems all ordered phases resist a finite amount of such chirality disorder, the homogeneous ones (polar flocks and active nematics) are unstable to any amount of disorder in the infinite-size limit. On the other hand, we find that the inhomogeneous solutions of the coexistence phase (bands) may resist a finite amount of chirality disorder even asymptotically.
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Affiliation(s)
- Bruno Ventejou
- Service de Physique de l'Etat Condensé, CEA, CNRS Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - Hugues Chaté
- Service de Physique de l'Etat Condensé, CEA, CNRS Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Computational Science Research Center, Beijing 100193, China
- Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée, 75005 Paris, France
| | - Raul Montagne
- Departamento de Fisica, Universidade Federal Rural de Pernambuco (UFRPE), 52171-900 Recife, Pernambuco, Brazil
| | - Xia-Qing Shi
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
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14
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Zhou Z, Joshi C, Liu R, Norton MM, Lemma L, Dogic Z, Hagan MF, Fraden S, Hong P. Machine learning forecasting of active nematics. SOFT MATTER 2021; 17:738-747. [PMID: 33220675 DOI: 10.1039/d0sm01316a] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Active nematics are a class of far-from-equilibrium materials characterized by local orientational order of force-generating, anisotropic constitutes. Traditional methods for predicting the dynamics of active nematics rely on hydrodynamic models, which accurately describe idealized flows and many of the steady-state properties, but do not capture certain detailed dynamics of experimental active nematics. We have developed a deep learning approach that uses a Convolutional Long-Short-Term-Memory (ConvLSTM) algorithm to automatically learn and forecast the dynamics of active nematics. We demonstrate our purely data-driven approach on experiments of 2D unconfined active nematics of extensile microtubule bundles, as well as on data from numerical simulations of active nematics.
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15
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Abstract
The emergence of macroscopic order and patterns is a central paradigm in systems of (self-)propelled agents and a key component in the structuring of many biological systems. The relationships between the ordering process and the underlying microscopic interactions have been extensively explored both experimentally and theoretically. While emerging patterns often show one specific symmetry (e.g., nematic lane patterns or polarized traveling flocks), depending on the symmetry of the alignment interactions patterns with different symmetries can apparently coexist. Indeed, recent experiments with an actomysin motility assay suggest that polar and nematic patterns of actin filaments can interact and dynamically transform into each other. However, theoretical understanding of the mechanism responsible remains elusive. Here, we present a kinetic approach complemented by a hydrodynamic theory for agents with mixed alignment symmetries, which captures the experimentally observed phenomenology and provides a theoretical explanation for the coexistence and interaction of patterns with different symmetries. We show that local, pattern-induced symmetry breaking can account for dynamically coexisting patterns with different symmetries. Specifically, in a regime with moderate densities and a weak polar bias in the alignment interaction, nematic bands show a local symmetry-breaking instability within their high-density core region, which induces the formation of polar waves along the bands. These instabilities eventually result in a self-organized system of nematic bands and polar waves that dynamically transform into each other. Our study reveals a mutual feedback mechanism between pattern formation and local symmetry breaking in active matter that has interesting consequences for structure formation in biological systems.
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16
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Mangeat M, Chatterjee S, Paul R, Rieger H. Flocking with a q-fold discrete symmetry: Band-to-lane transition in the active Potts model. Phys Rev E 2020; 102:042601. [PMID: 33212593 DOI: 10.1103/physreve.102.042601] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/11/2020] [Indexed: 11/06/2022]
Abstract
We study the q-state active Potts model (APM) on a two-dimensional lattice in which self-propelled particles have q internal states corresponding to the q directions of motion. A local alignment rule inspired by the ferromagnetic q-state Potts model and self-propulsion via biased diffusion according to the internal particle states elicits collective motion at high densities and low noise. We formulate a coarse-grained hydrodynamic theory with which we compute the phase diagrams of the APM for q=4 and q=6 and analyze the flocking dynamics in the coexistence region, where the high-density (polar liquid) phase forms a fluctuating stripe of coherently moving particles on the background of the low-density (gas) phase. A reorientation transition of the phase-separated profiles from transversal band motion to longitudinal lane formation is found, which is absent in the Vicsek model and the active Ising model. The origin of this reorientation transition is revealed by a stability analysis: for large velocities the transverse diffusivity approaches zero and stabilizes lanes. Computer simulations corroborate the analytical predictions of the flocking and reorientation transitions and validate the phase diagrams of the APM.
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Affiliation(s)
- Matthieu Mangeat
- Center for Biophysics & Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Swarnajit Chatterjee
- School of Mathematical & Computational Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Raja Paul
- School of Mathematical & Computational Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Heiko Rieger
- Center for Biophysics & Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
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Kokot G, Sokolov A, Snezhko A. Guided Self-Assembly and Control of Vortices in Ensembles of Active Magnetic Rollers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6957-6962. [PMID: 31756110 DOI: 10.1021/acs.langmuir.9b03023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Active magnetic colloids are capable of rich collective behavior and complex self-organization. The interplay between short- and long-range interactions taking place away from equilibrium often results in a spontaneous formation of localized dynamic microstructures. Here we report a method for guided self-assembly and control of self-organized colloidal vortices emerging in a ferromagnetic particle ensemble energized by a uniaxial alternating (ac) magnetic field. The structure of a vortex composed of rolling magnetic particles can be stabilized and manipulated by means of an additional strongly localized alternating magnetic field provided by a minicoil. By tuning the parameters of the localized field, we effectively control the dimensions and particle number density in the vortex. We find that the roller vortex self-organization is assisted by field-induced magnetic "steering" rather than magnetic field gradients and is only possible while the system is in the active (magnetic rollers) state. We demonstrate that parameters of the emergent vortex are efficiently tuned by a phase shift between alternating magnetic fields. The method for assisted self-organization of rolling magnetic colloids into a vortex with on-demand characteristics suggests a new tool for active matter control and manipulation that may lead to a development of new approaches toward the guided microscopic transport in active particle systems.
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Affiliation(s)
- Gašper Kokot
- Northwestern Argonne Institute of Science and Engineering (NAISE), Engineering Science and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Andrey Sokolov
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Alexey Snezhko
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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18
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Ma Z, Yang M, Ni R. Dynamic Assembly of Active Colloids: Theory and Simulation. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000021] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Zhan Ma
- School of Chemical and Biomedical EngineeringNanyang Technological University62 Nanyang Drive, 637459 Singapore
| | - Mingcheng Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190 China
- School of Physical SciencesUniversity of Chinese Academy of SciencesBeijing 100049 China
| | - Ran Ni
- School of Chemical and Biomedical EngineeringNanyang Technological University62 Nanyang Drive, 637459 Singapore
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19
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Emergence of self-organized multivortex states in flocks of active rollers. Proc Natl Acad Sci U S A 2020; 117:9706-9711. [PMID: 32300010 DOI: 10.1073/pnas.2000061117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Active matter, both synthetic and biological, demonstrates complex spatiotemporal self-organization and the emergence of collective behavior. A coherent rotational motion, the vortex phase, is of great interest because of its ability to orchestrate well-organized motion of self-propelled particles over large distances. However, its generation without geometrical confinement has been a challenge. Here, we show by experiments and computational modeling that concentrated magnetic rollers self-organize into multivortex states in an unconfined environment. We find that the neighboring vortices more likely occur with the opposite sense of rotation. Our studies provide insights into the mechanism for the emergence of coherent collective motion on the macroscale from the coupling between microscale rotation and translation of individual active elements. These results may stimulate design strategies for self-assembled dynamic materials and microrobotics.
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20
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Patelli A, Djafer-Cherif I, Aranson IS, Bertin E, Chaté H. Understanding Dense Active Nematics from Microscopic Models. PHYSICAL REVIEW LETTERS 2019; 123:258001. [PMID: 31922774 DOI: 10.1103/physrevlett.123.258001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 09/13/2019] [Indexed: 06/10/2023]
Abstract
We study dry, dense active nematics at both particle and continuous levels. Specifically, extending the Boltzmann-Ginzburg-Landau approach, we derive well-behaved hydrodynamic equations from a Vicsek-style model with nematic alignment and pairwise repulsion. An extensive study of the phase diagram shows qualitative agreement between the two levels of description. We find in particular that the dynamics of topological defects strongly depends on parameters and can lead to "arch" solutions forming a globally polar, smecticlike arrangement of Néel walls. We show how these configurations are at the origin of the defect ordered states reported previously. This work offers a detailed understanding of the theoretical description of dense active nematics directly rooted in their microscopic dynamics.
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Affiliation(s)
- Aurelio Patelli
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - Ilyas Djafer-Cherif
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- School of Mathematics, University of Bristol, Bristol BS8 1TW, United Kingdom
| | - Igor S Aranson
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Eric Bertin
- Univ. Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | - Hugues Chaté
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Computational Science Research Center, Beijing 100094, China
- LPTMC, Sorbonne Université, CNRS, 75005 Paris, France
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21
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Mahault B, Ginelli F, Chaté H. Quantitative Assessment of the Toner and Tu Theory of Polar Flocks. PHYSICAL REVIEW LETTERS 2019; 123:218001. [PMID: 31809144 DOI: 10.1103/physrevlett.123.218001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Indexed: 06/10/2023]
Abstract
We present a quantitative assessment of the Toner and Tu theory describing the universal scaling of fluctuations in polar phases of dry active matter. Using large-scale simulations of the Vicsek model in two and three dimensions, we find the overall phenomenology and generic algebraic scaling predicted by Toner and Tu, but our data on density correlations reveal some qualitative discrepancies. The values of the associated scaling exponents we estimate differ significantly from those conjectured in 1995. In particular, we identify a large crossover scale beyond which flocks are only weakly anisotropic. We discuss the meaning and consequences of these results.
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Affiliation(s)
- Benoît Mahault
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany
| | - Francesco Ginelli
- Department of Physics and Institute for Complex Systems and Mathematical Biology, Kings College, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom
- Dipartimento di Scienza e Alta Tecnologia and Center for Nonlinear and Complex Systems, Università degli Studi dell'Insubria, Via Valleggio 11, 22100 Como, Italy
| | - Hugues Chaté
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Beijing Computational Science Research Center, Beijing 100094, China
- LPTMC, CNRS UMR 7600, Université Pierre et Marie Curie, 75252 Paris, France
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22
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Maryshev I, Goryachev AB, Marenduzzo D, Morozov A. Dry active turbulence in a model for microtubule-motor mixtures. SOFT MATTER 2019; 15:6038-6043. [PMID: 31298679 DOI: 10.1039/c9sm00558g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the dynamics and phase behaviour of a dry suspension of microtubules and molecular motors. We obtain a set of continuum equations by rigorously coarse graining a microscopic model where motor-induced interactions lead to parallel or antiparallel ordering. Through numerical simulations, we show that this model generically creates either stable stripes, or a never-settling pattern where stripes periodically form, rotate and then split up. We derive a minimal model which displays the same instability as the full model, and clarifies the underlying physical mechanism. The necessary ingredients are an extensile flux arising from microtubule sliding and an interfacial torque favouring ordering along density gradients. We argue that our minimal model unifies various previous observations of chaotic behaviour in dry active matter into a general universality class.
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Affiliation(s)
- Ivan Maryshev
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK.
| | - Andrew B Goryachev
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK.
| | - Davide Marenduzzo
- SUPA, School of Physics and Astronomy, The University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
| | - Alexander Morozov
- SUPA, School of Physics and Astronomy, The University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
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23
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Barberis L, Peruani F. Phase separation and emergence of collective motion in a one-dimensional system of active particles. J Chem Phys 2019; 150:144905. [DOI: 10.1063/1.5085840] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lucas Barberis
- Université Côte d’Azur, Laboratoire J. A. Dieudonné, UMR 7351 CNRS, 06108 Nice, France
- IFEG, FaMAF, CONICET, UNC, X5000HUA Córdoba, Argentina
| | - Fernando Peruani
- Université Côte d’Azur, Laboratoire J. A. Dieudonné, UMR 7351 CNRS, 06108 Nice, France
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24
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Lemma LM, DeCamp SJ, You Z, Giomi L, Dogic Z. Statistical properties of autonomous flows in 2D active nematics. SOFT MATTER 2019; 15:3264-3272. [PMID: 30920553 PMCID: PMC6924514 DOI: 10.1039/c8sm01877d] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We study the dynamics of a tunable 2D active nematic liquid crystal composed of microtubules and kinesin motors confined to an oil-water interface. Kinesin motors continuously inject mechanical energy into the system through ATP hydrolysis, powering the relative microscopic sliding of adjacent microtubules, which in turn generates macroscale autonomous flows and chaotic dynamics. We use particle image velocimetry to quantify two-dimensional flows of active nematics and extract their statistical properties. In agreement with the hydrodynamic theory, we find that the vortex areas comprising the chaotic flows are exponentially distributed, which allows us to extract the characteristic system length scale. We probe the dependence of this length scale on the ATP concentration, which is the experimental knob that tunes the magnitude of the active stress. Our data suggest a possible mapping between the ATP concentration and the active stress that is based on the Michaelis-Menten kinetics that governs the motion of individual kinesin motors.
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Affiliation(s)
- Linnea M Lemma
- Department of Physics, Brandeis University, Waltham, MA 02454, USA
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25
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Miles CJ, Evans AA, Shelley MJ, Spagnolie SE. Active matter invasion of a viscous fluid: Unstable sheets and a no-flow theorem. PHYSICAL REVIEW LETTERS 2019; 122:098002. [PMID: 30932541 DOI: 10.1103/physrevlett.122.098002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 11/29/2018] [Indexed: 06/09/2023]
Abstract
We investigate the dynamics of a dilute suspension of hydrodynamically interacting motile or immotile stress-generating swimmers or particles as they invade a surrounding viscous fluid. Colonies of aligned pusher particles are shown to elongate in the direction of particle orientation and undergo a cascade of transverse concentration instabilities, governed at small times by an equation that also describes the Saffman-Taylor instability in a Hele-Shaw cell, or the Rayleigh-Taylor instability in a two-dimensional flow through a porous medium. Thin sheets of aligned pusher particles are always unstable, while sheets of aligned puller particles can either be stable (immotile particles), or unstable (motile particles) with a growth rate that is nonmonotonic in the force dipole strength. We also prove a surprising "no-flow theorem": a distribution initially isotropic in orientation loses isotropy immediately but in such a way that results in no fluid flow everywhere and for all time.
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Affiliation(s)
- Christopher J Miles
- Department of Physics, University of Michigan, 450 Church St., Ann Arbor, Michigan 48109, USA
| | - Arthur A Evans
- Department of Mathematics, University of Wisconsin-Madison, 480 Lincoln Dr., Madison, Wisconsin 53706, USA
| | - Michael J Shelley
- Flatiron Institute, Simons Foundation, New York, New York, USA; and Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
| | - Saverio E Spagnolie
- Department of Mathematics, University of Wisconsin-Madison, 480 Lincoln Dr., Madison, Wisconsin 53706, USA
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26
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Cai LB, Chaté H, Ma YQ, Shi XQ. Dynamical subclasses of dry active nematics. Phys Rev E 2019; 99:010601. [PMID: 30780307 DOI: 10.1103/physreve.99.010601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Indexed: 06/09/2023]
Abstract
We show that the dominant mode of alignment plays an important role in dry active nematics, leading to two dynamical subclasses defined by the nature of the instability of the nematic bands that characterize, in these systems, the coexistence phase separating the isotropic and fluctuating nematic states. In addition to the well-known instability inducing long undulations along the band, another stronger instability leading to the breakup of the band in many transversal segments may arise. We elucidate the origin of this strong instability for a realistic model of self-propelled rods and determine the high-order nonlinear terms responsible for it at the hydrodynamic level.
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Affiliation(s)
- Li-Bing Cai
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Hugues Chaté
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, China
- Service de Physique de l'Etat Condensé, CEA, CNRS Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Computational Science Research Center, Beijing 100094, China
| | - Yu-Qiang Ma
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Xia-Qing Shi
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, China
- Service de Physique de l'Etat Condensé, CEA, CNRS Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
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27
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Abstract
Active matter comprises individual units that convert energy into mechanical motion. In many examples, such as bacterial systems and biofilament assays, constituent units are elongated and can give rise to local nematic orientational order. Such "active nematics" systems have attracted much attention from both theorists and experimentalists. However, despite intense research efforts, data-driven quantitative modeling has not been achieved, a situation mainly due to the lack of systematic experimental data and to the large number of parameters of current models. Here, we introduce an active nematics system made of swarming filamentous bacteria. We simultaneously measure orientation and velocity fields and show that the complex spatiotemporal dynamics of our system can be quantitatively reproduced by a type of microscopic model for active suspensions whose important parameters are all estimated from comprehensive experimental data. This provides unprecedented access to key effective parameters and mechanisms governing active nematics. Our approach is applicable to different types of dense suspensions and shows a path toward more quantitative active matter research.
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28
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Joshi A, Putzig E, Baskaran A, Hagan MF. The interplay between activity and filament flexibility determines the emergent properties of active nematics. SOFT MATTER 2018; 15:94-101. [PMID: 30520495 DOI: 10.1039/c8sm02202j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Active nematics are microscopically driven liquid crystals that exhibit dynamical steady states characterized by the creation and annihilation of topological defects. Motivated by differences between previous simulations of active nematics based on rigid rods and experimental realizations based on semiflexible biopolymer filaments, we describe a large-scale simulation study of a particle-based computational model that explicitly incorporates filament semiflexibility. We find that energy injected into the system at the particle scale preferentially excites bend deformations, reducing the apparent filament bend modulus. The emergent characteristics of the active nematic depend on activity and flexibility only through this activity-renormalized bend 'modulus', demonstrating that apparent values of material parameters, such as the Frank 'constants', depend on activity. Thus, phenomenological parameters within continuum hydrodynamic descriptions of active nematics must account for this dependence. Further, we present a systematic way to estimate these parameters from observations of deformation fields and defect shapes in experimental or simulation data.
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Affiliation(s)
- Abhijeet Joshi
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
| | - Elias Putzig
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
| | - Aparna Baskaran
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
| | - Michael F Hagan
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
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29
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Abstract
Active matter is a wide class of nonequilibrium systems consisting of interacting self-propelled agents transducing the energy stored in the environment into mechanical motion. Numerous examples range from microscopic cytoskeletal filaments and swimming organisms (bacteria and unicellular algae), synthetic catalytic nanomotors, colloidal self-propelled Janus particles, to macroscopic bird flocks, fish schools, and even human crowds. Active matter demonstrates a remarkable tendency toward self-organization and development of collective states with the long-range spatial order. Furthermore, active materials exhibit properties that are not present in traditional materials like plastics or ceramics: self-repair, shape change, and adaptation. A suspension of microscopic swimmers, such as motile bacteria or self-propelled colloids (active suspensions), is possibly the simplest and the most explored realization of active matter. Recent studies of active suspensions revealed a wealth of unexpected behaviors, from a dramatic reduction of the effective viscosity, enhanced mixing and self-diffusion, rectification of chaotic motion, to artificial rheotaxis (drift against the imposed flow) and cross-stream migration. To date, most of the studies of active matter are performed in isotropic suspending medium, like water with the addition of some "fuel", e.g., nutrient for bacteria or H2O2 for catalytic bimetallic AuPt nanorods. A highly structured anisotropic suspending medium represented by lyotropic liquid crystal (water-soluble) opens enormous opportunities to control and manipulate active matter. Liquid crystals exhibit properties intermediate between solid and liquids; they may flow like a liquid but respond to deformations as a solid due to a crystal-like orientation of molecules. Liquid crystals doped by a small amount of active component represent a new class of composite materials (living liquid crystals or LLCs) with unusual mechanical and optical properties. LLCs demonstrate a variety of highly organized dynamic collective states, spontaneous formation of dynamic textures of topological defects (singularities of local molecular orientation), controlled and reconfigurable transport of cargo particles, manipulation of individual trajectories of microswimmers, and many others. Besides insights into fundamental mechanisms governing active materials, living liquid crystals may have intriguing applications, such as the design of new classes of soft adaptive bioinspired materials capable to respond to physical and chemical stimuli, such as light, magnetic, and electric fields, mechanical shear, airborne pollutants, and bacterial toxins. This Account details the most recent developments in the field of LLCs and discusses how the anisotropy of liquid crystals can be harnessed to control and manipulate active materials.
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Affiliation(s)
- Igor S. Aranson
- Departments of Biomedical Engineering, Chemistry and Mathematics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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30
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Shankar S, Ramaswamy S, Marchetti MC, Bowick MJ. Defect Unbinding in Active Nematics. PHYSICAL REVIEW LETTERS 2018; 121:108002. [PMID: 30240234 DOI: 10.1103/physrevlett.121.108002] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/18/2018] [Indexed: 06/08/2023]
Abstract
We formulate the statistical dynamics of topological defects in the active nematic phase, formed in two dimensions by a collection of self-driven particles on a substrate. An important consequence of the nonequilibrium drive is the spontaneous motility of strength +1/2 disclinations. Starting from the hydrodynamic equations of active nematics, we derive an interacting particle description of defects that includes active torques. We show that activity, within perturbation theory, lowers the defect-unbinding transition temperature, determining a critical line in the temperature-activity plane that separates the quasi-long-range ordered (nematic) and disordered (isotropic) phases. Below a critical activity, defects remain bound as rotational noise decorrelates the directed dynamics of +1/2 defects, stabilizing the quasi-long-range ordered nematic state. This activity threshold vanishes at low temperature, leading to a reentrant transition. At large enough activity, active forces always exceed thermal ones and the perturbative result fails, suggesting that in this regime activity will always disorder the system. Crucially, rotational diffusion being a two-dimensional phenomenon, defect unbinding cannot be described by a simplified one-dimensional model.
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Affiliation(s)
- Suraj Shankar
- Physics Department and Syracuse Soft and Living Matter Program, Syracuse University, Syracuse, New York 13244, USA
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
| | - Sriram Ramaswamy
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560 012, India
| | - M Cristina Marchetti
- Physics Department and Syracuse Soft and Living Matter Program, Syracuse University, Syracuse, New York 13244, USA
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
| | - Mark J Bowick
- Physics Department and Syracuse Soft and Living Matter Program, Syracuse University, Syracuse, New York 13244, USA
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
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31
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Bott MC, Winterhalter F, Marechal M, Sharma A, Brader JM, Wittmann R. Isotropic-nematic transition of self-propelled rods in three dimensions. Phys Rev E 2018; 98:012601. [PMID: 30110778 DOI: 10.1103/physreve.98.012601] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Indexed: 06/08/2023]
Abstract
Using overdamped Brownian dynamics simulations we investigate the isotropic-nematic (IN) transition of self-propelled rods in three spatial dimensions. For two well-known model systems (Gay-Berne potential and hard spherocylinders) we find that turning on activity moves to higher densities the phase boundary separating an isotropic phase from a (nonpolar) nematic phase. This active IN phase boundary is distinct from the boundary between isotropic and polar-cluster states previously reported in two-dimensional simulation studies and, unlike the latter, is not sensitive to the system size. We thus identify a generic feature of anisotropic active particles in three dimensions.
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Affiliation(s)
- M C Bott
- Soft Matter Theory, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - F Winterhalter
- Institut für Theoretische Physik, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - M Marechal
- Institut für Theoretische Physik, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - A Sharma
- Leibniz-Institut für Polymerforschung Dresden, 01069 Dresden, Germany
| | - J M Brader
- Soft Matter Theory, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - R Wittmann
- Soft Matter Theory, University of Fribourg, CH-1700 Fribourg, Switzerland
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32
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Kourbane-Houssene M, Erignoux C, Bodineau T, Tailleur J. Exact Hydrodynamic Description of Active Lattice Gases. PHYSICAL REVIEW LETTERS 2018; 120:268003. [PMID: 30004761 DOI: 10.1103/physrevlett.120.268003] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/23/2018] [Indexed: 06/08/2023]
Abstract
We introduce lattice gas models of active matter systems whose coarse-grained "hydrodynamic" description can be derived exactly. We illustrate our approach by considering two systems exhibiting two of the most studied collective behaviors in active matter: the motility-induced phase separation and the transition to collective motion. In both cases, we derive coupled partial differential equations describing the dynamics of the local density and polarization fields and show how they quantitatively predict the emerging properties of the macroscopic lattice gases.
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Affiliation(s)
| | - Clément Erignoux
- Instituto de Matemática Pura e Aplicada, CEP 22460-320, Rio de Janeiro, Brazil
| | - Thierry Bodineau
- CMAP, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
| | - Julien Tailleur
- Université Paris Diderot, Sorbonne Paris Cité, MSC, UMR 7057 CNRS, 75205 Paris, France
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33
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Huber L, Suzuki R, Krüger T, Frey E, Bausch AR. Emergence of coexisting ordered states in active matter systems. Science 2018; 361:255-258. [DOI: 10.1126/science.aao5434] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 01/22/2018] [Accepted: 05/16/2018] [Indexed: 01/16/2023]
Abstract
Active systems can produce a far greater variety of ordered patterns than conventional equilibrium systems. In particular, transitions between disorder and either polar- or nematically ordered phases have been predicted and observed in two-dimensional active systems. However, coexistence between phases of different types of order has not been reported. We demonstrate the emergence of dynamic coexistence of ordered states with fluctuating nematic and polar symmetry in an actomyosin motility assay. Combining experiments with agent-based simulations, we identify sufficiently weak interactions that lack a clear alignment symmetry as a prerequisite for coexistence. Thus, the symmetry of macroscopic order becomes an emergent and dynamic property of the active system. These results provide a pathway by which living systems can express different types of order by using identical building blocks.
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Affiliation(s)
- L. Huber
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Theresienstrasse 37, Germany
| | - R. Suzuki
- Lehrstuhl für Biophysik (E27), Technische Universität München, James-Franck-Strasse 1, D-85748 Garching, Germany
- Graduate School of Medicine, Kyoto University, 606-8501 Kyoto, Japan
- Institute for Integrated Cell-Material Sciences, Kyoto University, 606-8501 Kyoto, Japan
| | - T. Krüger
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Theresienstrasse 37, Germany
| | - E. Frey
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Theresienstrasse 37, Germany
| | - A. R. Bausch
- Lehrstuhl für Biophysik (E27), Technische Universität München, James-Franck-Strasse 1, D-85748 Garching, Germany
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Mahault B, Jiang XC, Bertin E, Ma YQ, Patelli A, Shi XQ, Chaté H. Self-Propelled Particles with Velocity Reversals and Ferromagnetic Alignment: Active Matter Class with Second-Order Transition to Quasi-Long-Range Polar Order. PHYSICAL REVIEW LETTERS 2018; 120:258002. [PMID: 29979075 DOI: 10.1103/physrevlett.120.258002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Indexed: 06/08/2023]
Abstract
We introduce and study in two dimensions a new class of dry, aligning active matter that exhibits a direct transition to orientational order, without the phase-separation phenomenology usually observed in this context. Characterized by self-propelled particles with velocity reversals and a ferromagnetic alignment of polarities, systems in this class display quasi-long-range polar order with continuously varying scaling exponents, yet a numerical study of the transition leads to conclude that it does not belong to the Berezinskii-Kosterlitz-Thouless universality class but is best described as a standard critical point with an algebraic divergence of correlations. We rationalize these findings by showing that the interplay between order and density changes the role of defects.
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Affiliation(s)
- B Mahault
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - X-C Jiang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
| | - E Bertin
- LIPHY, Université Grenoble Alpes and CNRS, F-38000 Grenoble, France
| | - Y-Q Ma
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - A Patelli
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - X-Q Shi
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
| | - H Chaté
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Beijing Computational Science Research Center, Beijing 100094, China
- Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée, 75005 Paris, France
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35
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Kim K, Yoshinaga N, Bhattacharyya S, Nakazawa H, Umetsu M, Teizer W. Large-scale chirality in an active layer of microtubules and kinesin motor proteins. SOFT MATTER 2018; 14:3221-3231. [PMID: 29670958 DOI: 10.1039/c7sm02298k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
During the early developmental process of organisms, the formation of left-right laterality requires a subtle mechanism, as it is associated with other principal body axes. Any inherent chiral feature in an egg cell can in principal trigger this spontaneous breaking of chiral symmetry. Individual microtubules, major cytoskeletal filaments, are known as chiral objects. However, to date there lacks convincing evidence of a hierarchical connection of the molecular nature of microtubules to large-scale chirality, particularly at the length scale of an entire cell. Here we assemble an in vitro active layer, consisting of microtubules and kinesin motor proteins, on a glass surface. Upon inclusion of methyl cellulose, the layered system exhibits a long-range active nematic phase, characterized by the global alignment of gliding MTs. This nematic order spans over the entire system size in the millimeter range and, remarkably, allows hidden collective chirality to emerge as counterclockwise global rotation of the active MT layer. The analysis based on our theoretical model suggests that the emerging global nematic order results from the local alignment of MTs, stabilized by methyl cellulose. It also suggests that the global rotation arises from the MTs' intrinsic curvature, leading to preferential handedness. Given its flexibility, this layered in vitro cytoskeletal system enables the study of membranous protein behavior responsible for important cellular developmental processes.
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Affiliation(s)
- Kyongwan Kim
- WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan
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36
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Abstract
Suspensions of motile bacteria or synthetic microswimmers, termed active matter, manifest a remarkable propensity for self-organization, and formation of large-scale coherent structures. Most active matter research deals with almost homogeneous in space systems and little is known about the dynamics of strongly heterogeneous active matter. Here we report on experimental and theoretical studies on the expansion of highly concentrated bacterial droplets into an ambient bacteria-free fluid. The droplet is formed beneath a rapidly rotating solid macroscopic particle inserted in the suspension. We observe vigorous instability of the droplet reminiscent of a violent explosion. The phenomenon is explained in terms of continuum first-principle theory based on the swim pressure concept. Our findings provide insights into the dynamics of active matter with strong density gradients and significantly expand the scope of experimental and analytic tools for control and manipulation of active systems.
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37
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Henkes S, Marchetti MC, Sknepnek R. Dynamical patterns in nematic active matter on a sphere. Phys Rev E 2018; 97:042605. [PMID: 29758687 DOI: 10.1103/physreve.97.042605] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Indexed: 01/24/2023]
Abstract
Using simulations of self-propelled agents with short-range repulsion and nematic alignment, we explore the dynamical phases of a dense active nematic confined to the surface of a sphere. We map the nonequilibrium phase diagram as a function of curvature, alignment strength, and activity. Our model reproduces several phases seen in recent experiments on active microtubule bundles confined the surfaces of vesicles. At low driving, we recover the equilibrium nematic ground state with four +1/2 defects. As the driving is increased, geodesic forces drive the transition to a polar band wrapping around an equator, with large empty spherical caps corresponding to two +1 defects at the poles. Upon further increasing activity, the bands fold onto themselves, and the system eventually transitions to a turbulent state marked by the proliferation of pairs of topological defects. We highlight the key role of the nematic persistence length in controlling pattern formation in these confined systems with positive Gaussian curvature.
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Affiliation(s)
- Silke Henkes
- Institute for Complex Systems and Mathematical Biology, Department of Physics, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom
| | - M Cristina Marchetti
- Department of Physics and Soft Matter Program, Syracuse University, Syracuse, New York 13244, USA
| | - Rastko Sknepnek
- School of Sciences and Engineering and School of Life Sciences, University of Dundee, Dundee DD1 4HN, United Kingdom
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38
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Shankar S, Ramaswamy S, Marchetti MC. Low-noise phase of a two-dimensional active nematic system. Phys Rev E 2018; 97:012707. [PMID: 29448420 DOI: 10.1103/physreve.97.012707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Indexed: 06/08/2023]
Abstract
We consider a collection of self-driven apolar particles on a substrate that organize into an active nematic phase at sufficiently high density or low noise. Using the dynamical renormalization group, we systematically study the two-dimensional fluctuating ordered phase in a coarse-grained hydrodynamic description involving both the nematic director and the conserved density field. In the presence of noise, we show that the system always displays only quasi-long-ranged orientational order beyond a crossover scale. A careful analysis of the nonlinearities permitted by symmetry reveals that activity is dangerously irrelevant over the linearized description, allowing giant number fluctuations to persist although now with strong finite-size effects and a nonuniversal scaling exponent. Nonlinear effects from the active currents lead to power-law correlations in the density field, thereby preventing macroscopic phase separation in the thermodynamic limit.
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Affiliation(s)
- Suraj Shankar
- Physics Department and Syracuse Soft & Living Matter Program, Syracuse University, Syracuse, New York 13244, USA
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
| | - Sriram Ramaswamy
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - M Cristina Marchetti
- Physics Department and Syracuse Soft & Living Matter Program, Syracuse University, Syracuse, New York 13244, USA
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39
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Das R, Kumar M, Mishra S. Order-disorder transition in active nematic: A lattice model study. Sci Rep 2017; 7:7080. [PMID: 28765553 PMCID: PMC5539249 DOI: 10.1038/s41598-017-07301-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 06/27/2017] [Indexed: 11/26/2022] Open
Abstract
We introduce a lattice model for active nematic composed of self-propelled apolar particles, study its different ordering states in the density-temperature parameter space, and compare with the corresponding equilibrium model. The active particles interact with their neighbours within the framework of the Lebwohl-Lasher model, and move anisotropically along their orientation to an unoccupied nearest neighbour lattice site. An interplay of the activity, thermal fluctuations and density gives rise distinct states in the system. For a fixed temperature, the active nematic shows a disordered isotropic state, a locally ordered inhomogeneous mixed state, and bistability between the inhomogeneous mixed and a homogeneous globally ordered state in different density regime. In the low temperature regime, the isotropic to the inhomogeneous mixed state transition occurs with a jump in the order parameter at a density less than the corresponding equilibrium disorder-order transition density. Our analytical calculations justify the shift in the transition density and the jump in the order parameter. We construct the phase diagram of the active nematic in the density-temperature plane.
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Affiliation(s)
- Rakesh Das
- S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, 700106, India.
| | - Manoranjan Kumar
- S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, 700106, India.
| | - Shradha Mishra
- S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, 700106, India.
- Department of Physics, Indian Institute of Technology (BHU), Varanasi, 221005, India.
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40
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Nishiguchi D, Nagai KH, Chaté H, Sano M. Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria. Phys Rev E 2017; 95:020601. [PMID: 28297912 DOI: 10.1103/physreve.95.020601] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 05/02/2023]
Abstract
We study the collective dynamics of elongated swimmers in a very thin fluid layer by devising long filamentous nontumbling bacteria. The strong confinement induces weak nematic alignment upon collision, which, for large enough density of cells, gives rise to global nematic order. This homogeneous but fluctuating phase, observed on the largest experimentally accessible scale of millimeters, exhibits the properties predicted by standard models for flocking, such as the Vicsek-style model of polar particles with nematic alignment: true long-range nematic order and nontrivial giant number fluctuations.
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Affiliation(s)
- Daiki Nishiguchi
- Department of Physics, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan
| | - Ken H Nagai
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Hugues Chaté
- Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Beijing Computational Science Research Center, Beijing 100094, China
| | - Masaki Sano
- Department of Physics, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan
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41
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Barberis L, Peruani F. Large-Scale Patterns in a Minimal Cognitive Flocking Model: Incidental Leaders, Nematic Patterns, and Aggregates. PHYSICAL REVIEW LETTERS 2016; 117:248001. [PMID: 28009185 DOI: 10.1103/physrevlett.117.248001] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Indexed: 05/27/2023]
Abstract
We study a minimal cognitive flocking model, which assumes that the moving entities navigate using the available instantaneous visual information exclusively. The model consists of active particles, with no memory, that interact by a short-ranged, position-based, attractive force, which acts inside a vision cone (VC), and lack velocity-velocity alignment. We show that this active system can exhibit-due to the VC that breaks Newton's third law-various complex, large-scale, self-organized patterns. Depending on parameter values, we observe the emergence of aggregates or millinglike patterns, the formation of moving-locally polar-files with particles at the front of these structures acting as effective leaders, and the self-organization of particles into macroscopic nematic structures leading to long-ranged nematic order. Combining simulations and nonlinear field equations, we show that position-based active models, as the one analyzed here, represent a new class of active systems fundamentally different from other active systems, including velocity-alignment-based flocking systems. The reported results are of prime importance in the study, interpretation, and modeling of collective motion patterns in living and nonliving active systems.
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Affiliation(s)
- Lucas Barberis
- Université Côte d'Azur, Laboratoire J.A. Dieudonné, UMR 7351 CNRS, Parc Valrose, F-06108 Nice Cedex 02, France
- IFEG, FaMAF, CONICET, UNC, X5000HUA Córdoba, Argentina
| | - Fernando Peruani
- Université Côte d'Azur, Laboratoire J.A. Dieudonné, UMR 7351 CNRS, Parc Valrose, F-06108 Nice Cedex 02, France
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42
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Großmann R, Peruani F, Bär M. Mesoscale pattern formation of self-propelled rods with velocity reversal. Phys Rev E 2016; 94:050602. [PMID: 27967147 DOI: 10.1103/physreve.94.050602] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Indexed: 11/07/2022]
Abstract
We study self-propelled particles with velocity reversal interacting by uniaxial (nematic) alignment within a coarse-grained hydrodynamic theory. Combining analytical and numerical continuation techniques, we show that the physics of this active system is essentially controlled by the reversal frequency. In particular, we find that elongated, high-density, ordered patterns, called bands, emerge via subcritical bifurcations from spatially homogeneous states. Our analysis reveals further that the interaction of bands is weakly attractive and, consequently, bands fuse upon collision in analogy with nonequilibrium nucleation processes. Moreover, we demonstrate that a renormalized positive line tension can be assigned to stable bands below a critical reversal rate, beyond which they are transversally unstable. In addition, we discuss the kinetic roughening of bands as well as their nonlinear dynamics close to the threshold of transversal instability. Altogether, the reduction of the multiparticle system onto the dynamics of bands provides a unified framework to understand the emergence and stability of nonequilibrium patterns in this self-propelled particle system. In this regard, our results constitute a proof of principle in favor of the hypothesis in microbiology that velocity reversal of gliding rod-shaped bacteria regulates the transitions between various self-organized patterns observed during the bacterial life cycle.
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Affiliation(s)
- Robert Großmann
- Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, D-10587 Berlin, Germany.,Laboratoire J. A. Dieudonné, Université de Nice Sophia Antipolis, UMR 7351 CNRS, Parc Valrose, F-06108 Nice Cedex 02, France
| | - Fernando Peruani
- Laboratoire J. A. Dieudonné, Université de Nice Sophia Antipolis, UMR 7351 CNRS, Parc Valrose, F-06108 Nice Cedex 02, France
| | - Markus Bär
- Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, D-10587 Berlin, Germany
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43
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Putzig E, Redner GS, Baskaran A, Baskaran A. Instabilities, defects, and defect ordering in an overdamped active nematic. SOFT MATTER 2016; 12:3854-9. [PMID: 26983376 PMCID: PMC5166704 DOI: 10.1039/c6sm00268d] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We consider a phenomenological continuum theory for an extensile, overdamped active nematic liquid crystal, applicable in the dense regime. Constructed from general principles, the theory is universal, with parameters independent of any particular microscopic realization. We show that it exhibits two distinct instabilities, one of which arises due to shear forces, and the other due to active torques. Both lead to the proliferation of defects. We focus on the active torque bend instability and find three distinct nonequilibrium steady states including a defect-ordered nematic in which +½ disclinations develop polar ordering. We characterize the phenomenology of these phases and identify the relationship of this theoretical description to experimental realizations and other theoretical models of active nematics.
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Affiliation(s)
- Elias Putzig
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
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44
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Chakraborti S, Mishra S, Pradhan P. Additivity, density fluctuations, and nonequilibrium thermodynamics for active Brownian particles. Phys Rev E 2016; 93:052606. [PMID: 27300950 DOI: 10.1103/physreve.93.052606] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Indexed: 06/06/2023]
Abstract
Using an additivity property, we study particle-number fluctuations in a system of interacting self-propelled particles, called active Brownian particles (ABPs), which consists of repulsive disks with random self-propulsion velocities. From a fluctuation-response relation, a direct consequence of additivity, we formulate a thermodynamic theory which captures the previously observed features of nonequilibrium phase transition in the ABPs from a homogeneous fluid phase to an inhomogeneous phase of coexisting gas and liquid. We substantiate the predictions of additivity by analytically calculating the subsystem particle-number distributions in the homogeneous fluid phase away from criticality where analytically obtained distributions are compatible with simulations in the ABPs.
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Affiliation(s)
- Subhadip Chakraborti
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Shradha Mishra
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Punyabrata Pradhan
- Department of Theoretical Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
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45
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Hagan MF, Baskaran A. Emergent self-organization in active materials. Curr Opin Cell Biol 2016; 38:74-80. [PMID: 26971116 DOI: 10.1016/j.ceb.2016.02.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/04/2016] [Accepted: 02/25/2016] [Indexed: 11/20/2022]
Abstract
Biological systems exhibit large-scale self-organized dynamics and structures which enable organisms to perform the functions of life. The field of active matter strives to develop and understand microscopically driven nonequilibrium materials, with emergent properties comparable to those of living systems. This review will describe two recently developed classes of active matter systems, in which simple building blocks-self-propelled colloidal particles or extensile rod-like particles-self-organize to form macroscopic structures with features not possible in equilibrium systems. We summarize the recent experimental and theoretical progress on each of these systems, and we present simple descriptions of the physics underlying their emergent behaviors.
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Affiliation(s)
- Michael F Hagan
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
| | - Aparna Baskaran
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
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46
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Actomyosin dynamics drive local membrane component organization in an in vitro active composite layer. Proc Natl Acad Sci U S A 2016; 113:E1645-54. [PMID: 26929326 DOI: 10.1073/pnas.1514030113] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The surface of a living cell provides a platform for receptor signaling, protein sorting, transport, and endocytosis, whose regulation requires the local control of membrane organization. Previous work has revealed a role for dynamic actomyosin in membrane protein and lipid organization, suggesting that the cell surface behaves as an active composite composed of a fluid bilayer and a thin film of active actomyosin. We reconstitute an analogous system in vitro that consists of a fluid lipid bilayer coupled via membrane-associated actin-binding proteins to dynamic actin filaments and myosin motors. Upon complete consumption of ATP, this system settles into distinct phases of actin organization, namely bundled filaments, linked apolar asters, and a lattice of polar asters. These depend on actin concentration, filament length, and actin/myosin ratio. During formation of the polar aster phase, advection of the self-organizing actomyosin network drives transient clustering of actin-associated membrane components. Regeneration of ATP supports a constitutively remodeling actomyosin state, which in turn drives active fluctuations of coupled membrane components, resembling those observed at the cell surface. In a multicomponent membrane bilayer, this remodeling actomyosin layer contributes to changes in the extent and dynamics of phase-segregating domains. These results show how local membrane composition can be driven by active processes arising from actomyosin, highlighting the fundamental basis of the active composite model of the cell surface, and indicate its relevance to the study of membrane organization.
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47
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Doostmohammadi A, Adamer MF, Thampi SP, Yeomans JM. Stabilization of active matter by flow-vortex lattices and defect ordering. Nat Commun 2016; 7:10557. [PMID: 26837846 PMCID: PMC4742889 DOI: 10.1038/ncomms10557] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 12/28/2015] [Indexed: 01/30/2023] Open
Abstract
Active systems, from bacterial suspensions to cellular monolayers, are continuously driven out of equilibrium by local injection of energy from their constituent elements and exhibit turbulent-like and chaotic patterns. Here we demonstrate both theoretically and through numerical simulations, that the crossover between wet active systems, whose behaviour is dominated by hydrodynamics, and dry active matter where any flow is screened, can be achieved by using friction as a control parameter. Moreover, we discover unexpected vortex ordering at this wet-dry crossover. We show that the self organization of vortices into lattices is accompanied by the spatial ordering of topological defects leading to active crystal-like structures. The emergence of vortex lattices, which leads to the positional ordering of topological defects, suggests potential applications in the design and control of active materials.
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Affiliation(s)
- Amin Doostmohammadi
- The Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP, UK
| | - Michael F. Adamer
- The Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP, UK
| | - Sumesh P. Thampi
- The Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP, UK
| | - Julia M. Yeomans
- The Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP, UK
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48
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Solon AP, Caussin JB, Bartolo D, Chaté H, Tailleur J. Pattern formation in flocking models: A hydrodynamic description. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:062111. [PMID: 26764636 DOI: 10.1103/physreve.92.062111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Indexed: 06/05/2023]
Abstract
We study in detail the hydrodynamic theories describing the transition to collective motion in polar active matter, exemplified by the Vicsek and active Ising models. Using a simple phenomenological theory, we show the existence of an infinity of propagative solutions, describing both phase and microphase separation, that we fully characterize. We also show that the same results hold specifically in the hydrodynamic equations derived in the literature for the active Ising model and for a simplified version of the Vicsek model. We then study numerically the linear stability of these solutions. We show that stable ones constitute only a small fraction of them, which, however, includes all existing types. We further argue that, in practice, a coarsening mechanism leads towards phase-separated solutions. Finally, we construct the phase diagrams of the hydrodynamic equations proposed to qualitatively describe the Vicsek and active Ising models and connect our results to the phenomenology of the corresponding microscopic models.
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Affiliation(s)
- Alexandre P Solon
- Université Paris Diderot, Sorbonne Paris Cité, MSC, UMR 7057 CNRS, 75205 Paris, France
| | - Jean-Baptiste Caussin
- Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon, Université de Lyon, CNRS, 46, allée d'Italie, 69007 Lyon, France
| | - Denis Bartolo
- Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon, Université de Lyon, CNRS, 46, allée d'Italie, 69007 Lyon, France
| | - Hugues Chaté
- Service de Physique de l'État Condensé, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette, France
- LPTMC, CNRS UMR 7600, Université Pierre & Marie Curie, 75252 Paris, France
- Beijing Computational Science Research Center, Beijing 100094, China
| | - Julien Tailleur
- Université Paris Diderot, Sorbonne Paris Cité, MSC, UMR 7057 CNRS, 75205 Paris, France
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49
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Sarkar N, Basu A. Role of interfacial friction for flow instabilities in a thin polar-ordered active fluid layer. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:052306. [PMID: 26651694 DOI: 10.1103/physreve.92.052306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Indexed: 06/05/2023]
Abstract
We construct a generic coarse-grained dynamics of a thin inflexible planar layer of polar-ordered suspension of active particles that is frictionally coupled to an embedding isotropic passive fluid medium with a friction coefficient Γ. Being controlled by Γ, our model provides a unified framework to describe the long-wavelength behavior of a variety of thin polar-ordered systems, ranging from wet to dry active matter and free-standing active films. Investigations of the linear instabilities around a chosen orientationally ordered uniform reference state reveal generic moving and static instabilities in the system that can depend sensitively on Γ. Based on our results, we discuss estimation of bounds on Γ in experimentally accessible systems.
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Affiliation(s)
- Niladri Sarkar
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Calcutta 700064, India
- Max-Planck Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, Dresden, D-01187 Germany
| | - Abhik Basu
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Calcutta 700064, India
- Max-Planck Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, Dresden, D-01187 Germany
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50
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DeCamp SJ, Redner GS, Baskaran A, Hagan MF, Dogic Z. Orientational order of motile defects in active nematics. NATURE MATERIALS 2015; 14:1110-5. [PMID: 26280224 PMCID: PMC4894651 DOI: 10.1038/nmat4387] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 07/08/2015] [Indexed: 05/18/2023]
Abstract
The study of liquid crystals at equilibrium has led to fundamental insights into the nature of ordered materials, as well as to practical applications such as display technologies. Active nematics are a fundamentally different class of liquid crystals, driven away from equilibrium by the autonomous motion of their constituent rod-like particles. This internally generated activity powers the continuous creation and annihilation of topological defects, which leads to complex streaming flows whose chaotic dynamics seem to destroy long-range order. Here, we study these dynamics in experimental and computational realizations of active nematics. By tracking thousands of defects over centimetre-scale distances in microtubule-based active nematics, we identify a non-equilibrium phase characterized by a system-spanning orientational order of defects. This emergent order persists over hours despite defect lifetimes of only seconds. Similar dynamical structures are observed in coarse-grained simulations, suggesting that defect-ordered phases are a generic feature of active nematics.
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Affiliation(s)
- Stephen J DeCamp
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Gabriel S Redner
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Aparna Baskaran
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Michael F Hagan
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Zvonimir Dogic
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
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