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Active Matter

Active matter systems are made up of units that consume energy. Physicists group flocks of birds, molecular motors and layers of vibrating grains together in this category because they all extract energy from their surroundings at a single particle level and transform it into mechanical work. By studying the behaviours that emerge, our understanding of these systems can be enhanced and new frameworks for investigating the statistical physics of out-of-equilibrium systems can be built.

This collection brings together research and reviews from across the Nature Research journals covering key aspects of active matter with selected content from Nature Communications, Nature, Nature Physics, Nature Materials, Nature Reviews Materials and Communications Physics.

Comment and reviews

  • Nature Communications | Review Article | open

    Active matter systems are made up of self-driven components which extract energy from their surroundings to generate mechanical work. Here the authors review the subfield of active nematics and provide a comparison between theoretical findings and the corresponding experimental realisations.

    • Amin Doostmohammadi
    • , Jordi Ignés-Mullol
    • , Julia M. Yeomans
    •  &  Francesc Sagués
  • Nature Reviews Materials | Review Article

    The field of active matter studies how internally driven motile components self-organize into large-scale dynamical states and patterns. This Review discusses how active matter concepts are important for understanding cell biology, and how the use of biochemical components enables the creation of new inherently non-equilibrium materials with unique properties that have so far been mostly restricted to living organisms.

    • Daniel Needleman
    •  &  Zvonimir Dogic
  • Nature News | News Feature

    From flocking birds to swarming molecules, physicists are seeking to understand 'active matter' — and looking for a fundamental theory of the living world.

    • Gabriel Popkin
  • Nature Physics | Progress Article

    Equilibrium physics is ill-equipped to explain all of life’s subtleties, largely because living systems are out of equilibrium. Attempts to overcome this problem have given rise to a lively field of research—and some surprising biological findings.

    • J. Prost
    • , F. Jülicher
    •  &  J-F. Joanny
  • Nature Physics | Review Article

    Evidence that ants communicate mechanically to move objects several times their size has prompted a theory that places the group near a transition between uncoordinated and coordinated motion. These findings and their implications are reviewed here.

    • Ofer Feinerman
    • , Itai Pinkoviezky
    • , Aviram Gelblum
    • , Ehud Fonio
    •  &  Nir S. Gov
  • Nature Physics | Review Article

    The behaviour of cells and tissues can be understood in terms of emergent mesoscale states that are determined by a set of physical properties. This Review surveys experimental evidence for these states and the physics underpinning them.

    • Xavier Trepat
    •  &  Erik Sahai

Theory and Modelling

  • Nature Communications | Article | open

    Active chiral fluids are a special case of active matter in which energy is introduced into rotational motion via local application of torque. Here Banerjee et al. develop a hydrodynamic theory of such active fluids and connect it with odd viscosity which was previously considered an abstract concept.

    • Debarghya Banerjee
    • , Anton Souslov
    • , Alexander G. Abanov
    •  &  Vincenzo Vitelli
  • Nature Communications | Article | open

    Collective self-organized behavior can be observed in a variety of systems such as colloids and microswimmers. Here O’Keeffe et al. propose a model of oscillators which move in space and tend to synchronize with neighboring oscillators and outline five types of collective self-organized states.

    • Kevin P. O’Keeffe
    • , Hyunsuk Hong
    •  &  Steven H. Strogatz
  • Nature Physics | Letter

    Ensuring topological protection of the edge states in candidate topological insulators is complicated by the need to break time-reversal symmetry. Polar active liquids present an innovative solution to this problem, as a new metamaterial design shows.

    • Anton Souslov
    • , Benjamin C. van Zuiden
    • , Denis Bartolo
    •  &  Vincenzo Vitelli
  • Nature Communications | Article | open

    Bacteria continuously inject energy into their surroundings and thus induce chaotic like flows, namely meso-scale turbulence. Here, the authors show that transition to meso-scale turbulence and inertial turbulence observed in pipes share the same scaling behavior that belongs to the directed percolation universality class.

    • Amin Doostmohammadi
    • , Tyler N. Shendruk
    • , Kristian Thijssen
    •  &  Julia M. Yeomans
  • Nature Communications | Article | open

    Active fluids consist of self-driven particles that can drive spontaneous flow without the intervention of external forces. Here Woodhouse et al. show how to design logic circuits using this phenomenon in active fluid networks, which could be further exploited for autonomous microfluidic computing.

    • Francis G. Woodhouse
    •  &  Jörn Dunkel

Synthetic Active Matter

  • Nature Communications | Article | open

    Manipulation of paramagnetic microparticles can be exploited for drug delivery. Here the authors manipulate a swarm of such particles and control its shape with a magnetic field so that it can elongate reversibly, split into smaller swarms and thus be guided through a maze with multiple parallel channels.

    • Jiangfan Yu
    • , Ben Wang
    • , Xingzhou Du
    • , Qianqian Wang
    •  &  Li Zhang
  • Nature Communications | Article | open

    Bacteria communicate and organize via quorum sensing which is determined by biochemical processes. Here the authors aim to reproduce this behaviour in a system of synthetic active particles whose motion is induced by an external beam which is in turn controlled by a feedback-loop which mimics quorum sensing.

    • Tobias Bäuerle
    • , Andreas Fischer
    • , Thomas Speck
    •  &  Clemens Bechinger
  • Communications Physics | Article | open

    Motile cilia are organelles found in eukaryotic cells and serve to swim or generate surface flows. The paper presents a theoretical and experimental study showing the systematic link between synchronisation state and the beating motion of active biological filaments.

    • Armando Maestro
    • , Nicolas Bruot
    • , Jurij Kotar
    • , Nariya Uchida
    • , Ramin Golestanian
    •  &  Pietro Cicuta
  • Nature Communications | Article | open

    Active systems utilize energy input to realize structural complexity and functional diversity. This work shows that magnetic colloidal rollers spontaneously self-organize into unconfined macroscopic vortices under a magnetic field, which can be used to transport inert particles across a flat surface.

    • Gašper Kokot
    •  &  Alexey Snezhko
  • Nature Communications | Article | open

    Active rotating particles were shown to undergo a phase separation through numerical simulations. Here the authors provide an experimental realization of this phenomenon by presenting an ensemble of 3D-printed robots that rotate in different directions and interact with each other.

    • Christian Scholz
    • , Michael Engel
    •  &  Thorsten Pöschel
  • Nature Communications | Article | open

    The cluster phase of active particles is one instance of the propensity of active matter to self-organize. Combining high-statistics experiments on Janus colloids and simple modeling, Ginot et al. provide a thorough characterization of cluster’s size and motion.

    • F. Ginot
    • , I. Theurkauff
    • , F. Detcheverry
    • , C. Ybert
    •  &  C. Cottin-Bizonne

Biological Active Matter

  • Nature Communications | Article | open

    Sokolov et al. have previously shown how bacteria are expelled in response to a rotating microparticle. Here the authors find that when the microparticle is spun at much higher rotation rates bacteria are trapped around it and then are expelled radially upon rotation cessation in an explosion-like manner.

    • Andrey Sokolov
    • , Leonardo Dominguez Rubio
    • , John F. Brady
    •  &  Igor S. Aranson
  • Nature Communications | Article | open

    The ability to generate microscale patterns and control microswimmers may be useful for engineering smart materials. Here Arlt et al. use genetically modified bacteria with fast response to changes in light intensity to produce light-induced patterns.

    • Jochen Arlt
    • , Vincent A. Martinez
    • , Angela Dawson
    • , Teuta Pilizota
    •  &  Wilson C. K. Poon
  • Nature Physics | Article

    Topological defects in a turbulent active nematic on a toroidal surface are shown to segregate in regions of opposite curvature. Simulations suggest that this behaviour may be controlled — or even suppressed — by tuning the level of activity.

    • Perry W. Ellis
    • , Daniel J. G. Pearce
    • , Ya-Wen Chang
    • , Guillermo Goldsztein
    • , Luca Giomi
    •  &  Alberto Fernandez-Nieves
  • Nature Communications | Article | open

    Tissue remodeling involves substantial involvement of the contractile actomyosin cytoskeleton. Here the authors model the spatiotemporal evolution of actomyosin densities during Drosophila germband extension and find affine and nonaffine deformations that depend on the magnitude of local contractile stress.

    • Deb Sankar Banerjee
    • , Akankshi Munjal
    • , Thomas Lecuit
    •  &  Madan Rao
  • Nature Communications | Article | open

    Active nematics consist of self-driven components that develop orientational order and turbulent flow. Here Guillamat et al. investigate an active nematic constrained in a quasi-2D geometrical setup and show that there exists an intrinsic length scale that determines the geometry in all forcing regimes.

    • P. Guillamat
    • , J. Ignés-Mullol
    •  &  F. Sagués
  • Nature Communications | Article | open

    Self-organization is observed in cytoskeletal systems but emergence of order from disorder is poorly understood. Using a high density actomyosin system, the authors capture the transition from disorder to order, which is driven by enhanced alignment effects caused by increase in multi-filament collisions.

    • Ryo Suzuki
    •  &  Andreas R. Bausch

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