1
|
Bayati P, Mallory SA. Orbits, Spirals, and Trapped States: Dynamics of a Phoretic Janus Particle in a Radial Concentration Gradient. ACS NANO 2024; 18:23047-23057. [PMID: 39137334 DOI: 10.1021/acsnano.4c05076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
A long-standing goal in colloidal active matter is to understand how gradients in fuel concentration influence the motion of phoretic Janus particles. Here, we present a theoretical description of the motion of a spherical phoretic Janus particle in the presence of a radial gradient of the chemical solute driving self-propulsion. Radial gradients are a geometry relevant to many scenarios in active matter systems and naturally arise due to the presence of a point source or sink of fuel. We derive an analytical solution for the Janus particle's velocity and quantify the influence of the radial concentration gradient on the particle's trajectory. Compared to a phoretic Janus particle in a linear gradient in fuel concentration, we uncover a much richer set of dynamic behaviors including circular orbits and trapped stationary states. We identify the ratio of the phoretic mobilities between the two domains of the Janus particle as a central quantity in tuning their dynamics. Our results provide a path for developing optimum protocols for tuning the dynamics of phoretic Janus particles and mixing fluid at the microscale. In addition, this work suggests a method for quantifying the surface properties of phoretic Janus particles, which have proven to be challenging to probe experimentally.
Collapse
Affiliation(s)
- Parvin Bayati
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Stewart A Mallory
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| |
Collapse
|
2
|
Chen SY, Lopez Rios HM, Olvera de la Cruz M, Driscoll M. Restructuring a passive colloidal suspension using a rotationally driven particle. SOFT MATTER 2024; 20:2151-2161. [PMID: 38351846 DOI: 10.1039/d4sm00010b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
The interaction between passive and active/driven particles has introduced a new way to control colloidal suspension properties from particle aggregation to crystallization. Here, we focus on the hydrodynamic interaction between a single rotational driven particle and a suspension of passive particles near the floor. Using experiments and Stokesian dynamics simulations that account for near-field lubrication, we demonstrate that the flow induced by the driven particle can induce long-ranged rearrangement in a passive suspension. We observe an accumulation of passive particles in front of the driven particle and a depletion of passive particles behind the driven particle. This restructuring generates a pattern that can span a range more than 10 times the driven particles radius. We further show that size scale of the pattern is only a function of the particles height above the floor.
Collapse
Affiliation(s)
- Shih-Yuan Chen
- Department of Physics & Astronomy, Northwestern University, Evanston, Illinois, 60208, USA.
| | - Hector Manuel Lopez Rios
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois, 60208, USA
| | - Monica Olvera de la Cruz
- Department of Physics & Astronomy, Northwestern University, Evanston, Illinois, 60208, USA.
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois, 60208, USA
| | - Michelle Driscoll
- Department of Physics & Astronomy, Northwestern University, Evanston, Illinois, 60208, USA.
| |
Collapse
|
3
|
Schiltz-Rouse E, Row H, Mallory SA. Kinetic temperature and pressure of an active Tonks gas. Phys Rev E 2023; 108:064601. [PMID: 38243499 DOI: 10.1103/physreve.108.064601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/06/2023] [Indexed: 01/21/2024]
Abstract
Using computer simulation and analytical theory, we study an active analog of the well-known Tonks gas, where active Brownian particles are confined to a periodic one-dimensional (1D) channel. By introducing the notion of a kinetic temperature, we derive an accurate analytical expression for the pressure and clarify the paradoxical behavior where active Brownian particles confined to 1D exhibit anomalous clustering but no motility-induced phase transition. More generally, this work provides a deeper understanding of pressure in active systems as we uncover a unique link between the kinetic temperature and swim pressure valid for active Brownian particles in higher dimensions.
Collapse
Affiliation(s)
- Elijah Schiltz-Rouse
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Hyeongjoo Row
- Department of Chemical and Biomolecular Engineering, UC Berkeley, Berkeley, California 94720, USA
| | - Stewart A Mallory
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| |
Collapse
|
4
|
Dias CS, Trivedi M, Volpe G, Araújo NAM, Volpe G. Environmental memory boosts group formation of clueless individuals. Nat Commun 2023; 14:7324. [PMID: 37957196 PMCID: PMC10643543 DOI: 10.1038/s41467-023-43099-0] [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: 06/12/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023] Open
Abstract
The formation of groups of interacting individuals improves performance and fitness in many decentralised systems, from micro-organisms to social insects, from robotic swarms to artificial intelligence algorithms. Often, group formation and high-level coordination in these systems emerge from individuals with limited information-processing capabilities implementing low-level rules of communication to signal to each other. Here, we show that, even in a community of clueless individuals incapable of processing information and communicating, a dynamic environment can coordinate group formation by transiently storing memory of the earlier passage of individuals. Our results identify a new mechanism of indirect coordination via shared memory that is primarily promoted and reinforced by dynamic environmental factors, thus overshadowing the need for any form of explicit signalling between individuals. We expect this pathway to group formation to be relevant for understanding and controlling self-organisation and collective decision making in both living and artificial active matter in real-life environments.
Collapse
Affiliation(s)
- Cristóvão S Dias
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
- Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal
| | - Manish Trivedi
- Department of Chemistry, University College London, 20 Gordon Street, WC1H 0AJ, London, UK
| | - Giovanni Volpe
- Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96, Gothenburg, Sweden.
| | - Nuno A M Araújo
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal.
- Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisboa, Portugal.
| | - Giorgio Volpe
- Department of Chemistry, University College London, 20 Gordon Street, WC1H 0AJ, London, UK.
| |
Collapse
|
5
|
Kushwaha P, Semwal V, Maity S, Mishra S, Chikkadi V. Phase separation of passive particles in active liquids. Phys Rev E 2023; 108:034603. [PMID: 37849120 DOI: 10.1103/physreve.108.034603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 08/03/2023] [Indexed: 10/19/2023]
Abstract
The transport properties of colloidal particles in active liquids have been studied extensively. It has led to a deeper understanding of the interactions between passive and active particles. However, the phase behavior of colloidal particles in active media has received little attention. Here, we present a combined experimental and numerical investigation of passive colloids dispersed in suspensions of active particles. Our study reveals dynamic clustering of colloids in active media due to an interplay of activity and attractive effective potential between the colloids. The strength of the effective potential is set by the size ratio of passive particles to the active ones. As the relative size of the passive particles increases, the effective potential becomes stronger and the average size of the clusters grows. The simulations reveal a macroscopic phase separation at sufficiently large size ratios. We will discuss the effect of density fluctuations of active particles on the nature of effective interactions between passive ones.
Collapse
Affiliation(s)
- Pragya Kushwaha
- Indian Institute of Science Education and Research, Pune 411008, India
| | - Vivek Semwal
- Indian Institute of Technology (BHU), Varanasi 221005, India
| | - Sayan Maity
- Indian Institute of Science Education and Research, Pune 411008, India
| | - Shradha Mishra
- Indian Institute of Technology (BHU), Varanasi 221005, India
| | | |
Collapse
|
6
|
Wei M, Ben Zion MY, Dauchot O. Reconfiguration, Interrupted Aging, and Enhanced Dynamics of a Colloidal Gel Using Photoswitchable Active Doping. PHYSICAL REVIEW LETTERS 2023; 131:018301. [PMID: 37478452 DOI: 10.1103/physrevlett.131.018301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/06/2023] [Accepted: 06/01/2023] [Indexed: 07/23/2023]
Abstract
We study quasi-2D gels made of a colloidal network doped with Janus particles activated by light. Following the gel formation, we monitor both the structure and dynamics before, during, and after the activation period. Before activity is switched on, the gel is slowly aging. During the activation, the mobility of the passive particles exhibits a characteristic scale-dependent response, while the colloidal network remains connected, and the gel maintains its structural integrity. Once activity is switched off, the gel stops aging and keeps the memory of the structure inherited from the active phase. Remarkably, the motility remains larger than that of the gel, before the active period. The system has turned into a genuinely softer gel, with frozen dynamics, but with more space for thermal fluctuations. The above conclusions remain valid long after the activity period.
Collapse
Affiliation(s)
- Mengshi Wei
- Gulliver UMR CNRS 7083, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France
| | - Matan Yah Ben Zion
- School of Physics and Astronomy, and the Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Olivier Dauchot
- Gulliver UMR CNRS 7083, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France
| |
Collapse
|
7
|
Bouvard J, Moisy F, Auradou H. Ostwald-like ripening in the two-dimensional clustering of passive particles induced by swimming bacteria. Phys Rev E 2023; 107:044607. [PMID: 37198759 DOI: 10.1103/physreve.107.044607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 03/28/2023] [Indexed: 05/19/2023]
Abstract
Clustering passive particles by active agents is a promising route for fabrication of colloidal structures. Here, we report the dynamic clustering of micrometric beads in a suspension of motile bacteria. We characterize the coarsening dynamics for various bead sizes, surface fractions, and bacterial concentrations. We show that the time scale τ for the onset of clustering is governed by the time of first encounter of diffusing beads. At large time (t≫τ), we observe a robust cluster growth as t^{1/3}, similar to the Ostwald ripening mechanism. From bead tracking measurements, we extract the short-range bacteria-induced attractive force at the origin of this clustering.
Collapse
Affiliation(s)
- J Bouvard
- Université Paris-Saclay, CNRS, FAST, 91405 Orsay, France
| | - F Moisy
- Université Paris-Saclay, CNRS, FAST, 91405 Orsay, France
| | - H Auradou
- Université Paris-Saclay, CNRS, FAST, 91405 Orsay, France
| |
Collapse
|
8
|
Kryuchkov NP, Nasyrov AD, Gursky KD, Yurchenko SO. Inertia changes evolution of motility-induced phase separation in active matter across particle activity. Phys Rev E 2023; 107:044601. [PMID: 37198785 DOI: 10.1103/physreve.107.044601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 03/14/2023] [Indexed: 05/19/2023]
Abstract
The effects of inertia in active matter and motility-induced phase separation (MIPS) have attracted growing interest but still remain poorly studied. We studied MIPS behavior in the Langevin dynamics across a broad range of particle activity and damping rate values with molecular dynamic simulations. Here we show that the MIPS stability region across particle activity values consists of several domains separated by discontinuous or sharp changes in susceptibility of mean kinetic energy. These domain boundaries have fingerprints in the system's kinetic energy fluctuations and characteristics of gas, liquid, and solid subphases, such as the number of particles, densities, or the power of energy release due to activity. The observed domain cascade is most stable at intermediate damping rates but loses its distinctness in the Brownian limit or vanishes along with phase separation at lower damping values.
Collapse
Affiliation(s)
- Nikita P Kryuchkov
- Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia
| | - Artur D Nasyrov
- Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia
| | - Konstantin D Gursky
- Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia
| | - Stanislav O Yurchenko
- Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia
| |
Collapse
|
9
|
Schildknecht D, Popova AN, Stellwagen J, Thomson M. Reinforcement learning reveals fundamental limits on the mixing of active particles. SOFT MATTER 2022; 18:617-625. [PMID: 34929723 DOI: 10.1039/d1sm01400e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The control of far-from-equilibrium physical systems, including active materials, requires advanced control strategies due to the non-linear dynamics and long-range interactions between particles, preventing explicit solutions to optimal control problems. In such situations, Reinforcement Learning (RL) has emerged as an approach to derive suitable control strategies. However, for active matter systems, it is an important open question how the mathematical structure and the physical properties determine the tractability of RL. In this paper, we demonstrate that RL can only find good mixing strategies for active matter systems that combine attractive and repulsive interactions. Using analytic results from dynamical systems theory, we show that combining both interaction types is indeed necessary for the existence of mixing-inducing hyperbolic dynamics and therefore the ability of RL to find homogeneous mixing strategies. In particular, we show that for drag-dominated translational-invariant particle systems, mixing relies on combined attractive and repulsive interactions. Therefore, our work demonstrates which experimental developments need to be made to make protein-based active matter applicable, and it provides some classification of microscopic interactions based on macroscopic behavior.
Collapse
Affiliation(s)
- Dominik Schildknecht
- Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Anastasia N Popova
- Applied and Computational Mathematics, California Institute of Technology, Pasadena CA, USA
| | - Jack Stellwagen
- School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Matt Thomson
- Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| |
Collapse
|
10
|
Mallory SA, Omar AK, Brady JF. Dynamic overlap concentration scale of active colloids. Phys Rev E 2021; 104:044612. [PMID: 34781543 DOI: 10.1103/physreve.104.044612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 10/06/2021] [Indexed: 11/07/2022]
Abstract
By introducing the notion of a dynamic overlap concentration scale, we identify additional universal features of the mechanical properties of active colloids. We codify these features by recognizing that the characteristic length scale of an active particle's trajectory, the run length, introduces a concentration scale ϕ^{*}. Large-scale simulations of repulsive active Brownian particles (ABPs) confirm that this run-length dependent concentration, the trajectory-space analog of the overlap concentration in polymer solutions, delineates distinct concentration regimes in which interparticle collisions alter particle trajectories. Using ϕ^{*} and concentration scales associated with colloidal jamming, the mechanical equation of state for ABPs collapses onto a set of principal curves that contain several overlooked features. The inclusion of these features qualitatively alters previous predictions of the behavior for active colloids, as we demonstrate by computing the spinodal for a suspension of purely repulsive ABPs. Our findings suggest that dynamic overlap concentration scales should help unravel the behavior of active and driven systems.
Collapse
Affiliation(s)
- Stewart A Mallory
- Department of Chemistry, The Pennsylvania State University, University Park, Pennyslvania 16802, USA
| | - Ahmad K Omar
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - John F Brady
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| |
Collapse
|
11
|
Forgács P, Libál A, Reichhardt C, Reichhardt CJO. Active matter shepherding and clustering in inhomogeneous environments. Phys Rev E 2021; 104:044613. [PMID: 34781504 DOI: 10.1103/physreve.104.044613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/08/2021] [Indexed: 11/07/2022]
Abstract
We consider a mixture of active and passive run-and-tumble disks in an inhomogeneous environment where only half of the sample contains quenched disorder or pinning. The disks are initialized in a fully mixed state of uniform density. We identify several distinct dynamical phases as a function of motor force and pinning density. At high pinning densities and high motor forces, there is a two-step process initiated by a rapid accumulation of both active and passive disks in the pinned region, which produces a large density gradient in the system. This is followed by a slower species phase separation process where the inactive disks are shepherded by the active disks into the pin-free region, forming a nonclustered fluid and producing a more uniform density with species phase separation. For higher pinning densities and low motor forces, the dynamics becomes very slow and the system maintains a strong density gradient. For weaker pinning and large motor forces, a floating clustered state appears, and the time-averaged density of the system is uniform. We illustrate the appearance of these phases in a dynamic phase diagram.
Collapse
Affiliation(s)
- P Forgács
- Mathematics and Computer Science Department, Babeş-Bolya University, Cluj 400084, Romania
| | - A Libál
- Mathematics and Computer Science Department, Babeş-Bolya University, Cluj 400084, Romania
| | - C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| |
Collapse
|
12
|
Xu F, Zhu J, Wang H, Zhang Z. Colloidal assembly manipulated by light-responsive Ag 3PO 4 nanoparticles. Chem Commun (Camb) 2021; 57:10347-10350. [PMID: 34528975 DOI: 10.1039/d1cc03997k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report controllable assembly of polystyrene (PS) microspheres via a photocatalytically driven electroosmotic flow deriving from UV irradiation of Ag3PO4 nanoparticles in water. A series of assembly phases, including crystallites, chains and gels, are programmed by systematically modulating the UV intensity, the packing density of the PS microspheres and the concentration of the Ag3PO4 nanoparticles. Our findings demonstrate an important ability of light-responsive nanoparticles for colloidal assembly, which offers a new pathway toward effective manipulation of assembly at the microscale.
Collapse
Affiliation(s)
- Fei Xu
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, and Institute for Advanced Study, School of Physical Science and Technology, Soochow University, Suzhou 215123, China.
| | - Jiao Zhu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Huaguang Wang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Zexin Zhang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, and Institute for Advanced Study, School of Physical Science and Technology, Soochow University, Suzhou 215123, China. .,College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| |
Collapse
|
13
|
Kryuchkov NP, Yurchenko SO. Collective excitations in active fluids: Microflows and breakdown in spectral equipartition of kinetic energy. J Chem Phys 2021; 155:024902. [PMID: 34266286 DOI: 10.1063/5.0054854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effect of particle activity on collective excitations in active fluids of microflyers is studied. With an in silico study, we observed an oscillating breakdown of equipartition (uniform spectral distribution) of kinetic energy in reciprocal space. The phenomenon is related to short-range velocity-velocity correlations that were realized without forming of long-lived mesoscale vortices in the system. This stands in contrast to well-known mesoscale turbulence operating in active nematic systems (bacterial or artificial) and reveals the features of collective dynamics in active fluids, which should be important for structural transitions and glassy dynamics in active matter.
Collapse
Affiliation(s)
- Nikita P Kryuchkov
- Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, 105005 Moscow, Russia
| | - Stanislav O Yurchenko
- Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, 105005 Moscow, Russia
| |
Collapse
|
14
|
Kim SY, Liu S, Sohn S, Jacobs J, Shattuck MD, O'Hern CS, Schroers J, Loewenberg M, Kramer-Bottiglio R. Static-state particle fabrication via rapid vitrification of a thixotropic medium. Nat Commun 2021; 12:3768. [PMID: 34145267 PMCID: PMC8213858 DOI: 10.1038/s41467-021-23992-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 05/18/2021] [Indexed: 11/09/2022] Open
Abstract
Functional particles that respond to external stimuli are spurring technological evolution across various disciplines. While large-scale production of functional particles is needed for their use in real-life applications, precise control over particle shapes and directional properties has remained elusive for high-throughput processes. We developed a high-throughput emulsion-based process that exploits rapid vitrification of a thixotropic medium to manufacture diverse functional particles in large quantities. The vitrified medium renders stationary emulsion droplets that preserve their shape and size during solidification, and energetic fields can be applied to build programmed anisotropy into the particles. We showcase mass-production of several functional particles, including low-melting point metallic particles, self-propelling Janus particles, and unidirectionally-magnetized robotic particles, via this static-state particle fabrication process.
Collapse
Affiliation(s)
- Sang Yup Kim
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA.,Department of Mechanical Engineering, Sogang University, Seoul, Republic of Korea
| | - Shanliangzi Liu
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA.,School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Sungwoo Sohn
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Jane Jacobs
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Mark D Shattuck
- Department of Physics, City University of New York, New York, NY, USA
| | - Corey S O'Hern
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Jan Schroers
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Michael Loewenberg
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA
| | - Rebecca Kramer-Bottiglio
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA.
| |
Collapse
|
15
|
Mallory SA, Bowers ML, Cacciuto A. Universal reshaping of arrested colloidal gels via active doping. J Chem Phys 2020; 153:084901. [PMID: 32872893 DOI: 10.1063/5.0016514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Colloids that interact via a short-range attraction serve as the primary building blocks for a broad range of self-assembled materials. However, one of the well-known drawbacks to this strategy is that these building blocks rapidly and readily condense into a metastable colloidal gel. Using computer simulations, we illustrate how the addition of a small fraction of purely repulsive self-propelled colloids, a technique referred to as active doping, can prevent the formation of this metastable gel state and drive the system toward its thermodynamically favored crystalline target structure. The simplicity and robust nature of this strategy offers a systematic and generic pathway to improving the self-assembly of a large number of complex colloidal structures. We discuss in detail the process by which this feat is accomplished and provide quantitative metrics for exploiting it to modulate the self-assembly. We provide evidence for the generic nature of this approach by demonstrating that it remains robust under a number of different anisotropic short-ranged pair interactions in both two and three dimensions. In addition, we report on a novel microphase in mixtures of passive and active colloids. For a broad range of self-propelling velocities, it is possible to stabilize a suspension of fairly monodisperse finite-size crystallites. Surprisingly, this microphase is also insensitive to the underlying pair interaction between building blocks. The active stabilization of these moderately sized monodisperse clusters is quite remarkable and should be of great utility in the design of hierarchical self-assembly strategies. This work further bolsters the notion that active forces can play a pivotal role in directing colloidal self-assembly.
Collapse
Affiliation(s)
- S A Mallory
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - M L Bowers
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - A Cacciuto
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| |
Collapse
|
16
|
Row H, Brady JF. Reverse osmotic effect in active matter. Phys Rev E 2020; 101:062604. [PMID: 32688587 DOI: 10.1103/physreve.101.062604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
In nonequilibrium active matter systems, a spatial variation in activity can lead to a spatial variation in concentration of active particles satisfying, at steady state, the condition nU=const [Schnitzer, Phys. Rev. E 48, 2553 (1993)1063-651X10.1103/PhysRevE.48.2553; Tailleur and Cates, Phys. Rev. Lett. 100, 218103 (2008)PRLTAO0031-900710.1103/PhysRevLett.100.218103], where n is the number density and U is the active (swim) speed. We show that this condition holds even when the variation is abrupt and when thermal Brownian motion is present provided that the Péclet number is large. This spatial variation in swim speed and concentration produces a fluid pressure distribution that drives a reverse osmotic flow-fluid flows from regions of high concentration to low.
Collapse
Affiliation(s)
- Hyeongjoo Row
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - John F Brady
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| |
Collapse
|
17
|
Abstract
Large-scale collective behavior in suspensions of active particles can be understood from the balance of statistical forces emerging beyond the direct microscopic particle interactions. Here we review some aspects of the collective forces that can arise in suspensions of self-propelled active Brownian particles: wall forces under confinement, interfacial forces, and forces on immersed bodies mediated by the suspension. Even for non-aligning active particles, these forces are intimately related to a non-uniform polarization of particle orientations induced by walls and bodies, or inhomogeneous density profiles. We conclude by pointing out future directions and promising areas for the application of collective forces in synthetic active matter, as well as their role in living active matter.
Collapse
Affiliation(s)
- Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany.
| |
Collapse
|
18
|
Kolb T, Klotsa D. Active binary mixtures of fast and slow hard spheres. SOFT MATTER 2020; 16:1967-1978. [PMID: 31859309 DOI: 10.1039/c9sm01799b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We computationally studied the phase behavior and dynamics of binary mixtures of active particles, where each species had distinct activities leading to distinct velocities, fast and slow. We obtained phase diagrams demonstrating motility-induced phase separation (MIPS) upon varying the activity and concentration of each species, and extended current kinetic theory of active/passive mixtures to active/active mixtures. We discovered two regimes of behavior quantified through the participation of each species in the dense phase compared to their monodisperse counterparts. In regime I (active/passive and active/weakly-active), we found that the dense phase was segregated by particle type into domains of fast and slow particles. Moreover, fast particles were suppressed from entering the dense phase while slow particles were enhanced entering the dense phase, compared to monodisperse systems of all-fast or all-slow particles. These effects decayed asymptotically as the activity of the slow species increased, approaching the activity of the fast species until they were negligible (regime II). In regime II, the dense phase was homogeneously mixed and each species participated in the dense phase as if it were it a monodisperse system (i.e. not mixed at all). Finally, we showed that a weighted average of constituent particle activities, which we term the net activity, defines a binodal for the MIPS transition in active/active binary mixtures. We examined the critical point of the transition and found a critical exponent (β = 0.45) in agreement with similar studies on monodisperse systems, and distinct from equilibrium systems.
Collapse
Affiliation(s)
- Thomas Kolb
- Department of Chemistry, University of North Carolina at Chapel Hill, USA and Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, USA.
| | - Daphne Klotsa
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, USA.
| |
Collapse
|
19
|
Omar AK, Wang ZG, Brady JF. Microscopic origins of the swim pressure and the anomalous surface tension of active matter. Phys Rev E 2020; 101:012604. [PMID: 32069575 DOI: 10.1103/physreve.101.012604] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Indexed: 06/10/2023]
Abstract
The unique pressure exerted by active particles-the "swim" pressure-has proven to be a useful quantity in explaining many of the seemingly confounding behaviors of active particles. However, its use has also resulted in some puzzling findings including an extremely negative surface tension between phase separated active particles. Here, we demonstrate that this contradiction stems from the fact that the swim pressure is not a true pressure. At a boundary or interface, the reduction in particle swimming generates a net active force density-an entirely self-generated body force. The pressure at the boundary, which was previously identified as the swim pressure, is in fact an elevated (relative to the bulk) value of the traditional particle pressure that is generated by this interfacial force density. Recognizing this unique mechanism for stress generation allows us to define a much more physically plausible surface tension. We clarify the utility of the swim pressure as an "equivalent pressure" (analogous to those defined from electrostatic and gravitational body forces) and the conditions in which this concept can be appropriately applied.
Collapse
Affiliation(s)
- Ahmad K Omar
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Zhen-Gang Wang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - John F Brady
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| |
Collapse
|
20
|
Xu D, Zhao L, Zhang K, Lu ZY. Dynamic self-assembly of block copolymers regulated by time-varying building block composition via reversible chemical reaction. Sci China Chem 2019. [DOI: 10.1007/s11426-019-9589-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
21
|
Szakasits ME, Saud KT, Mao X, Solomon MJ. Rheological implications of embedded active matter in colloidal gels. SOFT MATTER 2019; 15:8012-8021. [PMID: 31497836 DOI: 10.1039/c9sm01496a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Colloidal gels represent an important class of soft matter, in which networks formed due to strong, short-range interactions display solid-like mechanical properties, such as a finite low-frequency elastic modulus. Here we examine the effect of embedded active colloids on the linear viscoelastic moduli of fractal cluster colloidal gels. We find that the autonomous, out-of-equilibrium dynamics of active colloids incorporated into the colloidal network decreases gel elasticity, in contrast to observed stiffening effects of myosin motors in actin networks. Fractal cluster gels are formed by the well-known mechanism of aggregating polystyrene colloids through addition of divalent electrolyte. Active Janus particles with a platinum hemisphere are created from the same polystyrene colloids and homogeneously embedded in the gels at dilute concentration at the time of aggregation. Upon addition of hydrogen peroxide - a fuel that drives the diffusiophoretic motion of the embedded Janus particles - the microdynamics and mechanical rheology change in proportion to the concentration of hydrogen peroxide and the number of active colloids. We propose a theoretical explanation of this effect in which the decrease in modulus is mediated by active motion-induced softening of the inter-particle attraction. Furthermore, we characterize the failure of the fluctuation-dissipation theorem in the active gels by identifying a discrepancy between the frequency-dependent macroscopic viscoelastic moduli and the values predicted by microrheology from measurement of the gel microdynamics. These findings support efforts to engineer gels for autonomous function by tuning the microscopic dynamics of embedded active particles. Such reconfigurable gels, with multi-state mechanical properties, could find application in materials such as paints and coatings, pharmaceuticals, self-healing materials, and soft robotics.
Collapse
Affiliation(s)
- Megan E Szakasits
- Department of Chemical Engineering, University of Michigan, Ann Arbor, USA.
| | - Keara T Saud
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, USA
| | - Xiaoming Mao
- Department of Physics, University of Michigan, Ann Arbor, USA
| | - Michael J Solomon
- Department of Chemical Engineering, University of Michigan, Ann Arbor, USA.
| |
Collapse
|
22
|
Ramananarivo S, Ducrot E, Palacci J. Activity-controlled annealing of colloidal monolayers. Nat Commun 2019; 10:3380. [PMID: 31358762 PMCID: PMC6662715 DOI: 10.1038/s41467-019-11362-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 07/04/2019] [Indexed: 11/26/2022] Open
Abstract
Molecular motors are essential to the living, generating fluctuations that boost transport and assist assembly. Active colloids, that consume energy to move, hold similar potential for man-made materials controlled by forces generated from within. Yet, their use as a powerhouse in materials science lacks. Here we show a massive acceleration of the annealing of a monolayer of passive beads by moderate addition of self-propelled microparticles. We rationalize our observations with a model of collisions that drive active fluctuations and activate the annealing. The experiment is quantitatively compared with Brownian dynamic simulations that further unveil a dynamical transition in the mechanism of annealing. Active dopants travel uniformly in the system or co-localize at the grain boundaries as a result of the persistence of their motion. Our findings uncover the potential of internal activity to control materials and lay the groundwork for the rise of materials science beyond equilibrium.
Collapse
Affiliation(s)
- Sophie Ramananarivo
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0319, USA
- Ladhyx, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau Cedex, France
| | - Etienne Ducrot
- Center for Soft Matter Research, Department of Physics, New York University, 726 Broadway, New York, NY, 10003, USA
| | - Jeremie Palacci
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0319, USA.
| |
Collapse
|
23
|
Mallory SA, Cacciuto A. Activity-Enhanced Self-Assembly of a Colloidal Kagome Lattice. J Am Chem Soc 2019; 141:2500-2507. [DOI: 10.1021/jacs.8b12165] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Stewart A. Mallory
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Angelo Cacciuto
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| |
Collapse
|