1
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Decayeux J, Fries J, Dahirel V, Jardat M, Illien P. Isotropic active colloids: explicit vs. implicit descriptions of propulsion mechanisms. SOFT MATTER 2023; 19:8997-9005. [PMID: 37965908 DOI: 10.1039/d3sm00763d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Modeling the couplings between active particles often neglects the possible many-body effects that control the propulsion mechanism. Accounting for such effects requires the explicit modeling of the molecular details at the origin of activity. Here, we take advantage of a recent two-dimensional model of isotropic active particles whose propulsion originates from the interactions between solute particles in the bath. The colloid catalyzes a chemical reaction in its vicinity, which results in a local phase separation of solute particles, and the density fluctuations of solute particles cause the enhanced diffusion of the colloid. In this paper, we investigate an assembly of such active particles, using (i) an explicit model, where the microscopic dynamics of the solute particles is accounted for; and (ii) an implicit model, whose parameters are inferred from the explicit model at infinite dilution. In the explicit solute model, the long-time diffusion coefficient of the active colloids strongly decreases with density, an effect which is not captured by the derived implicit model. This suggests that classical models, which usually decouple pair interactions from activity, fail to describe collective dynamics in active colloidal systems driven by solute-solute interactions.
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Affiliation(s)
- Jeanne Decayeux
- Sorbonne Université, CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), 4 Place Jussieu, 75005 Paris, France
| | - Jacques Fries
- Sorbonne Université, CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), 4 Place Jussieu, 75005 Paris, France
| | - Vincent Dahirel
- Sorbonne Université, CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), 4 Place Jussieu, 75005 Paris, France
| | - Marie Jardat
- Sorbonne Université, CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), 4 Place Jussieu, 75005 Paris, France
| | - Pierre Illien
- Sorbonne Université, CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), 4 Place Jussieu, 75005 Paris, France
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2
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Huang Y, Wu C, Dai J, Liu B, Cheng X, Li X, Cao Y, Chen J, Li Z, Tang J. Tunable Self-Thermophoretic Nanomotors with Polymeric Coating. J Am Chem Soc 2023; 145:19945-19952. [PMID: 37641545 DOI: 10.1021/jacs.3c06322] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Thermophoretic micro/nanomotors (MNMs) generate self-propulsion without a chemical reaction. Intrinsically, this promises excellent biocompatibility and is thus suitable for biomedical applications. However, their propulsion efficiency is severely limited due to the poor understanding of the thermophoretic process, which dominates the conversion from thermal energy into mechanical movement. We here developed a series of self-thermophoresis light-powered MNMs with variable surface coatings and discovered obvious self-thermophoresis propulsion enhancement of the polymeric layer. An intrinsically negative self-thermophoretic movement is also observed for the first time in the MNM system. We propose that enthalpic contributions from polymer-solvent interactions should play a fundamental role in the self-thermophoretic MNMs. Quantitative microcalorimetry and molecular dynamics simulations are performed to support our hypothesis. The polymer solvation enthalpy and coating thickness influences on self-thermophoresis are investigated, further highlighting the essential enthalpy contributions to thermophoresis. Our work indicates that surface grafting would be important in designing high-efficiency thermally driven nanorobotic systems for biomedical applications.
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Affiliation(s)
- Yaxin Huang
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Changjin Wu
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Jia Dai
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Biyuan Liu
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Xiang Cheng
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Xiaofeng Li
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Yingnan Cao
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Jingyuan Chen
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
| | - Zhigang Li
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Jinyao Tang
- Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China
- State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Hong Kong 999077, China
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3
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Tkachenko G, Truong VG, Esporlas CL, Sanskriti I, Nic Chormaic S. Evanescent field trapping and propulsion of Janus particles along optical nanofibers. Nat Commun 2023; 14:1691. [PMID: 36973283 PMCID: PMC10043011 DOI: 10.1038/s41467-023-37448-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 03/07/2023] [Indexed: 03/29/2023] Open
Abstract
Small composite objects, known as Janus particles, drive sustained scientific interest primarily targeted at biomedical applications, where such objects act as micro- or nanoscale actuators, carriers, or imaging agents. A major practical challenge is to develop effective methods for the manipulation of Janus particles. The available long-range methods mostly rely on chemical reactions or thermal gradients, therefore having limited precision and strong dependency on the content and properties of the carrier fluid. To tackle these limitations, we propose the manipulation of Janus particles (here, silica microspheres half-coated with gold) by optical forces in the evanescent field of an optical nanofiber. We find that Janus particles exhibit strong transverse localization on the nanofiber and much faster propulsion compared to all-dielectric particles of the same size. These results establish the effectiveness of near-field geometries for optical manipulation of composite particles, where new waveguide-based or plasmonic solutions could be envisaged.
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Affiliation(s)
- Georgiy Tkachenko
- Light-Matter Interactions for Quantum Technologies Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, 904-0495, Okinawa, Japan.
| | - Viet Giang Truong
- Light-Matter Interactions for Quantum Technologies Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, 904-0495, Okinawa, Japan
| | - Cindy Liza Esporlas
- Light-Matter Interactions for Quantum Technologies Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, 904-0495, Okinawa, Japan
| | - Isha Sanskriti
- Light-Matter Interactions for Quantum Technologies Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, 904-0495, Okinawa, Japan
| | - Síle Nic Chormaic
- Light-Matter Interactions for Quantum Technologies Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, 904-0495, Okinawa, Japan.
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4
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Decayeux J, Jardat M, Illien P, Dahirel V. Conditions for the propulsion of a colloid surrounded by a mesoscale phase separation. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:96. [PMID: 36459281 DOI: 10.1140/epje/s10189-022-00247-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023]
Abstract
We study a two-dimensional model of an active isotropic colloid whose propulsion is linked to the interactions between solute particles of the bath. The colloid catalyzes a chemical reaction in its vicinity, that yields a local phase separation of solute particles. The density fluctuations of solute particles result in the enhanced diffusion of the colloid. Using numerical simulations, we thoroughly investigate the conditions under which activity occurs, and we establish a state diagram for the activity of the colloid as a function of the parameters of the model. We use the generated data to unravel a key observable that controls the existence and the intensity of activity: The filling fraction of the reaction area. Remarkably, we finally show that propulsion also occurs in three-dimensional geometries, which confirms the interest of this mechanism for experimental applications.
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Affiliation(s)
- Jeanne Decayeux
- Sorbonne Université, CNRS, Laboratoire PHENIX (Physicochimie des Electrolytes et Nanosystèmes Interfaciaux)), UMR 8234, F-75005 Paris, France
| | - Marie Jardat
- Sorbonne Université, CNRS, Laboratoire PHENIX (Physicochimie des Electrolytes et Nanosystèmes Interfaciaux)), UMR 8234, F-75005 Paris, France
| | - Pierre Illien
- Sorbonne Université, CNRS, Laboratoire PHENIX (Physicochimie des Electrolytes et Nanosystèmes Interfaciaux)), UMR 8234, F-75005 Paris, France
| | - Vincent Dahirel
- Sorbonne Université, CNRS, Laboratoire PHENIX (Physicochimie des Electrolytes et Nanosystèmes Interfaciaux)), UMR 8234, F-75005 Paris, France.
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5
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Xie K, Gorin B, Cerbus RT, Alvarez L, Rampnoux JM, Kellay H. Activity Induced Rigidity of Liquid Droplets. PHYSICAL REVIEW LETTERS 2022; 129:138001. [PMID: 36206417 DOI: 10.1103/physrevlett.129.138001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/18/2022] [Accepted: 08/25/2022] [Indexed: 06/16/2023]
Abstract
Here we show that encapsulating active Janus particles within a drop renders it more resistant to deformation. This drop is deformed under the action of an extensional flow. Such deformation is primarily resisted by the drop interfacial tension. When the particles are active under the action of laser illumination, the deformation decreases signaling an increase in effective tension or Laplace pressure. This increase is attributed to the activity of the particles. Our results using numerous drop sizes, particle number densities, and active velocities show that the obtained increase agrees surprisingly well, over an extended range, with a standard expression for the pressure engendered by an ensemble of active particles, proposed years ago but not tested yet in three dimensions.
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Affiliation(s)
- Kaili Xie
- Université de Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - Benjamin Gorin
- Université de Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - Rory T Cerbus
- Université de Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
| | - Laura Alvarez
- Université de Bordeaux, CNRS, CRPP, UMR 5031, 33600 Pessac, France
| | | | - Hamid Kellay
- Université de Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France
- Institut Universitaire de France, 75005 Paris, France
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6
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Domínguez A, Popescu MN. A fresh view on phoresis and self-phoresis. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Abstract
Progress in optical manipulation has stimulated remarkable advances in a wide range of fields, including materials science, robotics, medical engineering, and nanotechnology. This Review focuses on an emerging class of optical manipulation techniques, termed heat-mediated optical manipulation. In comparison to conventional optical tweezers that rely on a tightly focused laser beam to trap objects, heat-mediated optical manipulation techniques exploit tailorable optothermo-matter interactions and rich mass transport dynamics to enable versatile control of matter of various compositions, shapes, and sizes. In addition to conventional tweezing, more distinct manipulation modes, including optothermal pulling, nudging, rotating, swimming, oscillating, and walking, have been demonstrated to enhance the functionalities using simple and low-power optics. We start with an introduction to basic physics involved in heat-mediated optical manipulation, highlighting major working mechanisms underpinning a variety of manipulation techniques. Next, we categorize the heat-mediated optical manipulation techniques based on different working mechanisms and discuss working modes, capabilities, and applications for each technique. We conclude this Review with our outlook on current challenges and future opportunities in this rapidly evolving field of heat-mediated optical manipulation.
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Affiliation(s)
- Zhihan Chen
- Materials Science & Engineering Program, Texas Materials Institute, and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jingang Li
- Materials Science & Engineering Program, Texas Materials Institute, and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yuebing Zheng
- Materials Science & Engineering Program, Texas Materials Institute, and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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8
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Araki T, Gomez-Solano JR, Maciołek A. Relaxation to steady states of a binary liquid mixture around an optically heated colloid. Phys Rev E 2022; 105:014123. [PMID: 35193287 DOI: 10.1103/physreve.105.014123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
We study the relaxation dynamics of a binary liquid mixture near a light-absorbing Janus particle after switching on and off illumination using experiments and theoretical models. The dynamics is controlled by the temperature gradient formed around the heated particle. Our results show that the relaxation is asymmetric: The approach to a nonequilibrium steady state is much slower than the return to thermal equilibrium. Approaching a nonequilibrium steady state after a sudden temperature change is a two-step process that overshoots the response of spatial variance of the concentration field. The initial growth of concentration fluctuations after switching on illumination follows a power law in agreement with the hydrodynamic and purely diffusive model. The energy outflow from the system after switching off illumination is well described by a stretched exponential function of time with characteristic time proportional to the ratio of the energy stored in the steady state to the total energy flux in this state.
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Affiliation(s)
- Takeaki Araki
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Juan Ruben Gomez-Solano
- Instituto de Física, Universidad Nacional Autónoma de Mexico, Ciudad de Mexico, Código Postal 04510, Mexico
| | - Anna Maciołek
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland
- Max-Planck-Institut für Intelligente Systeme Stuttgart, Heisenbergstraße 3, D-70569 Stuttgart, Germany
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9
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Abstract
Active matter comprises self-driven units, such as bacteria and synthetic microswimmers, that can spontaneously form complex patterns and assemble into functional microdevices. These processes are possible thanks to the out-of-equilibrium nature of active-matter systems, fueled by a one-way free-energy flow from the environment into the system. Here, we take the next step in the evolution of active matter by realizing a two-way coupling between active particles and their environment, where active particles act back on the environment giving rise to the formation of superstructures. In experiments and simulations we observe that, under light-illumination, colloidal particles and their near-critical environment create mutually-coupled co-evolving structures. These structures unify in the form of active superstructures featuring a droplet shape and a colloidal engine inducing self-propulsion. We call them active droploids-a portmanteau of droplet and colloids. Our results provide a pathway to create active superstructures through environmental feedback.
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10
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Auschra S, Bregulla A, Kroy K, Cichos F. Thermotaxis of Janus particles. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:90. [PMID: 34218345 PMCID: PMC8254728 DOI: 10.1140/epje/s10189-021-00090-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 06/07/2021] [Indexed: 05/26/2023]
Abstract
The interactions of autonomous microswimmers play an important role for the formation of collective states of motile active matter. We study them in detail for the common microswimmer-design of two-faced Janus spheres with hemispheres made from different materials. Their chemical and physical surface properties may be tailored to fine-tune their mutual attractive, repulsive or aligning behavior. To investigate these effects systematically, we monitor the dynamics of a single gold-capped Janus particle in the external temperature field created by an optically heated metal nanoparticle. We quantify the orientation-dependent repulsion and alignment of the Janus particle and explain it in terms of a simple theoretical model for the induced thermoosmotic surface fluxes. The model reveals that the particle's angular velocity is solely determined by the temperature profile on the equator between the Janus particle's hemispheres and their phoretic mobility contrast. The distortion of the external temperature field by their heterogeneous heat conductivity is moreover shown to break the apparent symmetry of the problem.
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Affiliation(s)
- Sven Auschra
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Andreas Bregulla
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
| | - Klaus Kroy
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Frank Cichos
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
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11
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Schmidt F, Šípová-Jungová H, Käll M, Würger A, Volpe G. Non-equilibrium properties of an active nanoparticle in a harmonic potential. Nat Commun 2021; 12:1902. [PMID: 33772007 PMCID: PMC7998004 DOI: 10.1038/s41467-021-22187-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 03/04/2021] [Indexed: 11/09/2022] Open
Abstract
Active particles break out of thermodynamic equilibrium thanks to their directed motion, which leads to complex and interesting behaviors in the presence of confining potentials. When dealing with active nanoparticles, however, the overwhelming presence of rotational diffusion hinders directed motion, leading to an increase of their effective temperature, but otherwise masking the effects of self-propulsion. Here, we demonstrate an experimental system where an active nanoparticle immersed in a critical solution and held in an optical harmonic potential features far-from-equilibrium behavior beyond an increase of its effective temperature. When increasing the laser power, we observe a cross-over from a Boltzmann distribution to a non-equilibrium state, where the particle performs fast orbital rotations about the beam axis. These findings are rationalized by solving the Fokker-Planck equation for the particle's position and orientation in terms of a moment expansion. The proposed self-propulsion mechanism results from the particle's non-sphericity and the lower critical point of the solution.
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Affiliation(s)
- Falko Schmidt
- Department of Physics, University of Gothenburg, SE-41296, Gothenburg, Sweden
| | - Hana Šípová-Jungová
- Department of Physics, Chalmers University of Technology, SE-41296, Gothenburg, Sweden
| | - Mikael Käll
- Department of Physics, Chalmers University of Technology, SE-41296, Gothenburg, Sweden
| | - Alois Würger
- Laboratoire Ondes et Matière d'Aquitaine, Université de Bordeaux & CNRS, F-33405, Talence, France.
| | - Giovanni Volpe
- Department of Physics, University of Gothenburg, SE-41296, Gothenburg, Sweden.
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12
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Würger A. Thermoelectric Ratchet Effect for Charge Carriers with Hopping Dynamics. PHYSICAL REVIEW LETTERS 2021; 126:068001. [PMID: 33635717 DOI: 10.1103/physrevlett.126.068001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/30/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
We show that the huge Seebeck coefficients observed recently for ionic conductors arise from a ratchet effect where activated jumps between neighbor sites are rectified by a temperature gradient, thus driving mobile ions toward the cold. For complex systems with mobile molecules like water or polyethylene glycol, there is an even more efficient diffusiophoretic transport mechanism, proportional to the thermally induced concentration gradient of the molecular component. Without free parameters, our model describes experiments on the ionic liquid EMIM-TFSI and hydrated NaPSS, and it qualitatively accounts for polymer electrolyte membranes with Seebeck coefficients of hundreds of k_{B}/e.
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Affiliation(s)
- Alois Würger
- Université de Bordeaux & CNRS, LOMA (UMR 5798), 33405 Talence, France
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13
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Domínguez A, Popescu MN, Rohwer CM, Dietrich S. Self-Motility of an Active Particle Induced by Correlations in the Surrounding Solution. PHYSICAL REVIEW LETTERS 2020; 125:268002. [PMID: 33449719 DOI: 10.1103/physrevlett.125.268002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/09/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
Current models of phoretic transport rely on molecular forces creating a "diffuse" particle-fluid interface. We investigate theoretically an alternative mechanism, in which a diffuse interface emerges solely due to a nonvanishing correlation length of the surrounding solution. This mechanism can drive self-motility of a chemically active particle. Numerical estimates indicate that the velocity can reach micrometers per second. The predicted phenomenology includes a bilinear dependence of the velocity on the activity and a possible double velocity reversal upon varying the correlation length.
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Affiliation(s)
- Alvaro Domínguez
- Física Teórica, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla, Spain
- Instituto Carlos I de Física Teórica y Computacional, 18071 Granada, Spain
| | - M N Popescu
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
| | - C M Rohwer
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
- Department of Mathematics & Applied Mathematics, University of Cape Town, 7701 Rondebosch, Cape Town, South Africa
| | - S Dietrich
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
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14
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Gomez-Solano JR, Roy S, Araki T, Dietrich S, Maciołek A. Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture. SOFT MATTER 2020; 16:8359-8371. [PMID: 32781461 DOI: 10.1039/d0sm00964d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A gold-capped Janus particle suspended in a near-critical binary liquid mixture can self-propel under illumination. We have immobilized such a particle in a narrow channel and carried out a combined experimental and theoretical study of the non-equilibrium dynamics of a binary solvent around it - lasting from the very moment of switching illumination on until the steady state is reached. In the theoretical study we use both a purely diffusive and a hydrodynamic model, which we solve numerically. Our results demonstrate a remarkable complexity of the time evolution of the concentration field around the colloid. This evolution is governed by the combined effects of the temperature gradient and the wettability, and crucially depends on whether the colloid is free to move or is trapped. For the trapped colloid, all approaches indicate that the early time dynamics is purely diffusive and characterized by composition layers travelling with constant speed from the surface of the colloid into the bulk of the solvent. Subsequently, hydrodynamic effects set in. Anomalously large nonequilibrium fluctuations, which result from the temperature gradient and the vicinity of the critical point of the binary liquid mixture, give rise to strong concentration fluctuations in the solvent and to permanently changing coarsening patterns not observed for a mobile particle. The early time dynamics around initially still Janus colloids produces a force which is able to set the Janus colloid into motion. The propulsion due to this transient dynamics is in the direction opposite to that observed after the steady state is attained.
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Affiliation(s)
- Juan Ruben Gomez-Solano
- Instituto de Fisica, Universidad Nacional Autonoma de México, Apdo. Postal 20-364, 01000, Ciudad de México, Mexico
| | - Sutapa Roy
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany and IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - Takeaki Araki
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - S Dietrich
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany and IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - Anna Maciołek
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany and IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany and Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland.
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15
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Zhou C, Gao C, Lin Z, Wang D, Li Y, Yuan Y, Zhu B, He Q. Autonomous Motion of Bubble-Powered Carbonaceous Nanoflask Motors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:7039-7045. [PMID: 31927899 DOI: 10.1021/acs.langmuir.9b03398] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report a carbonaceous nanomotor with a characteristic flask-like hollow structure that can autonomously move under the propulsion of oxygen bubbles. The carbonaceous nanoflask (CNF) motor was fabricated by encapsulating platinum nanoparticles (Pt NPs) into the hollow cavity of the CNF. The internally encapsulated Pt NPs act as catalysts to decompose hydrogen peroxide (H2O2) fuel into oxygen bubbles. The generated oxygen bubbles recoil the motion of the CNF motors. Besides, the velocity of CNF motors can be controlled by adjusting the concentration of the H2O2 solution. The motion velocity increases with the increase of H2O2 concentration, up to 109.25 μm s-1 at 10% H2O2. This study provides important implications for understanding the motion behaviors of nanomotors with an internal cavity, and the self-propelled CNF motors as smart carrier systems have potential applications in the future.
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Affiliation(s)
- Chang Zhou
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Micro/Nanotechnology Research Centre, Harbin Institute of Technology, Yi Kuang Jie 2, Harbin 150080, China
| | - Changyong Gao
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Micro/Nanotechnology Research Centre, Harbin Institute of Technology, Yi Kuang Jie 2, Harbin 150080, China
| | - Zhihua Lin
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Micro/Nanotechnology Research Centre, Harbin Institute of Technology, Yi Kuang Jie 2, Harbin 150080, China
| | - Daolin Wang
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Micro/Nanotechnology Research Centre, Harbin Institute of Technology, Yi Kuang Jie 2, Harbin 150080, China
| | - Yue Li
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Micro/Nanotechnology Research Centre, Harbin Institute of Technology, Yi Kuang Jie 2, Harbin 150080, China
| | - Ye Yuan
- Chemistry and Chemical Engineering College, Inner Mongolia University, College Road 235, Hohhot 010021, China
| | - Baohua Zhu
- Chemistry and Chemical Engineering College, Inner Mongolia University, College Road 235, Hohhot 010021, China
| | - Qiang He
- Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of Education, Micro/Nanotechnology Research Centre, Harbin Institute of Technology, Yi Kuang Jie 2, Harbin 150080, China
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16
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Zhong J, Huang C. Thermal-Driven Ion Transport in Porous Materials for Thermoelectricity Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1418-1422. [PMID: 31948237 DOI: 10.1021/acs.langmuir.9b03141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Transport of thermal-driven ions in porous materials has not been clearly explained yet, while this transport has great application potential in co-generation of vapor and electricity for a bi-layer seawater desalination system. In this work, by taking into account the actually structure of a porous material, we theoretically modeled the thermal-driven ion transport in a porous material and also the resultant current and potential produced by such a transport. With models solved by the finite element method, it turns out that a porous material with a cross section of 30 × 10 mm2 could give a thermal current of about 27.2 mA, a thermal potential of about 63.7 mV, and a thermal power of about 433.2 μW, which are large enough to drive commercial electronic devices. This work provides a possibility of a vapor electricity co-generation in a bi-layer desalination system.
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Affiliation(s)
- Jinxin Zhong
- Center for Phononics and Thermal Energy Science, China-EU Joint Lab for Nanophononics, School of Physics Science and Engineering , Tongji University , Shanghai 200092 , China
- School of Electrical and Power Engineering , China University of Mining and Technology , Xuzhou 221116 , P. R. China
| | - Congliang Huang
- School of Electrical and Power Engineering , China University of Mining and Technology , Xuzhou 221116 , P. R. China
- Department of Mechanical Engineering , University of Colorado , Boulder , Colorado 80309-0427 , United States
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17
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Wang Y, Duan W, Zhou C, Liu Q, Gu J, Ye H, Li M, Wang W, Ma X. Phoretic Liquid Metal Micro/Nanomotors as Intelligent Filler for Targeted Microwelding. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1905067. [PMID: 31664739 DOI: 10.1002/adma.201905067] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/03/2019] [Indexed: 05/23/2023]
Abstract
Micro/nanomotors (MNMs) have emerged as active micro/nanoplatforms that can move and perform functions at small scales. Much of their success, however, hinges on the use of functional properties of new materials. Liquid metals (LMs), due to their good electrical conductivity, biocompatibility, and flexibility, have attracted considerable attentions in the fields of flexible electronics, biomedicine, and soft robotics. The design and construction of LM-based motors is therefore a research topic with tremendous prospects, however current approaches are mostly limited to macroscales. Here, the fabrication of an LM-MNM (made of Galinstan, a gallium-indium-tin alloy) is reported and its potential application as an on-demand, self-targeting welding filler is demonstrated. These LM-MNMs (as small as a few hundred nanometers) are half-coated with a thin layer of platinum (Pt) and move in H2 O2 via self-electrophoresis. In addition, the LM-MNMs roaming in a silver nanowire network can move along the nanowires and accumulate at the contact junctions where they become fluidic and achieve junction microwelding at room temperature by reacting with acid vapor. This work presents an intelligent and soft nanorobot capable of repairing circuits by welding at small scales, thus extending the pool of available self-propelled MNMs and introducing new applications.
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Affiliation(s)
- Yong Wang
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Wendi Duan
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Chao Zhou
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Qing Liu
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Jiahui Gu
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Heng Ye
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Mingyu Li
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Wei Wang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Xing Ma
- State Key Laboratory of Advanced Welding and Joining (Shenzhen) and Flexible Printed Electronic Technology Center, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
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18
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Speck T. Thermodynamic approach to the self-diffusiophoresis of colloidal Janus particles. Phys Rev E 2019; 99:060602. [PMID: 31330705 DOI: 10.1103/physreve.99.060602] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Indexed: 01/02/2023]
Abstract
Most available theoretical predictions for the self-diffusiophoretic motion of colloidal particles are based on the hydrodynamic thin boundary layer approximation in combination with a solvent body force due to a self-generated local solute gradient. This gradient is enforced through specifying boundary conditions, typically without accounting for the thermodynamic cost to maintain the gradient. Here, we present an alternative thermodynamic approach that exploits a direct link between dynamics and entropy production: the local detailed balance condition. We study two cases: First, we revisit self-propulsion in a demixing binary solvent. At variance with a slip velocity, we find that propulsion is due to forces at the poles that are perpendicular to the particle surface. Second, for catalytic swimmers driven through liberating chemical free energy we recover previous expressions. In both cases we argue that propulsion is due to asymmetric dissipation and not simply due to an asymmetric concentration of molecular solutes.
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Affiliation(s)
- Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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19
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Araki T, Maciołek A. Illumination-induced motion of a Janus nanoparticle in binary solvents. SOFT MATTER 2019; 15:5243-5254. [PMID: 31198923 DOI: 10.1039/c9sm00509a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Using a fluid particle dynamics method we numerically investigate the motion of a spherical Janus particle suspended in a binary liquid mixture, which emerges under heating of one-half of a colloid surface. The method treats simultaneously the flow of the solvent and the motion of the particle, hence, the velocity of the particle can be computed directly. Our approach accounts for a phenomenon of critical adsorption, therefore, a particle that is adsorptionwise nonneutral is always completely covered by an adsorption layer (droplet). In order to establish the mechanism of self-propulsion, we study systematically various combinations of adsorption preference on both hemispheres of the Janus colloid as function of the heating power for symmetric and nonsymmetric binary solvents and for various particle sizes in three spatial dimensions. Only for a particle for which the heated hemisphere is neutral whereas the other hemisphere prefers one of the two components of the mixture does the reversal of the direction of motion occur. The particle self-propels much faster in nonsymmetric binary solvents. Self-propulsion originates from a gradient of mechanical stress, in a way similar to the Marangoni effect. This stress is not localized at the edge but distributed within the whole droplet. We compare our findings with the experimental observations and other theoretical results.
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Affiliation(s)
- Takeaki Araki
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
| | - Anna Maciołek
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland. and Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
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20
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Uspal WE, Popescu MN, Dietrich S, Tasinkevych M. Active Janus colloids at chemically structured surfaces. J Chem Phys 2019; 150:204904. [DOI: 10.1063/1.5091760] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- W. E. Uspal
- Department of Mechanical Engineering, University of Hawai’i at Mnoa, 2540 Dole Street, Holmes Hall 302, Honolulu, Hawaii 96822, USA
| | - M. N. Popescu
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany and IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - S. Dietrich
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany and IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - M. Tasinkevych
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande P-1749-016 Lisboa, Portugal and Centro de Física Teórica e Computacional, Universidade de Lisboa, Campo Grande P-1749-016 Lisboa, Portugal
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21
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Schmidt F, Liebchen B, Löwen H, Volpe G. Light-controlled assembly of active colloidal molecules. J Chem Phys 2019; 150:094905. [PMID: 30849878 DOI: 10.1063/1.5079861] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Thanks to a constant energy input, active matter can self-assemble into phases with complex architectures and functionalities such as living clusters that dynamically form, reshape, and break-up, which are forbidden in equilibrium materials by the entropy maximization (or free energy minimization) principle. The challenge to control this active self-assembly has evoked widespread efforts typically hinging on engineering of the properties of individual motile constituents. Here, we provide a different route, where activity occurs as an emergent phenomenon only when individual building blocks bind together in a way that we control by laser light. Using experiments and simulations of two species of immotile microspheres, we exemplify this route by creating active molecules featuring a complex array of behaviors, becoming migrators, spinners, and rotators. The possibility to control the dynamics of active self-assembly via light-controllable nonreciprocal interactions will inspire new approaches to understand living matter and to design active materials.
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Affiliation(s)
- Falko Schmidt
- Department of Physics, University of Gothenburg, SE-41296 Gothenburg, Sweden
| | - Benno Liebchen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Giovanni Volpe
- Department of Physics, University of Gothenburg, SE-41296 Gothenburg, Sweden
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22
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Shen Z, Würger A, Lintuvuori JS. Hydrodynamic self-assembly of active colloids: chiral spinners and dynamic crystals. SOFT MATTER 2019; 15:1508-1521. [PMID: 30672958 DOI: 10.1039/c8sm02352b] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Active colloids self-organise into a variety of collective states, ranging from highly motile "molecules" to complex 2D structures. Using large-scale simulations, we show that hydrodynamic interactions, together with a gravity-like aligning field, lead to tunable self-assembly of active colloidal spheres near a surface. The observed structures depend on the hydrodynamic characteristics: particles driven at the front, pullers, form small chiral spinners consisting of two or three particles, whereas those driven at the rear, pushers, assemble into large dynamic aggregates. The rotational motion of the puller spinners, arises from spontaneous breaking of the internal chirality. Our results show that the fluid flow mediates chiral transfer between neighbouring spinners. Finally we show that the chirality of the individual spinners controls the topology of the self-assembly in solution: homochiral samples assemble into a hexagonally symmetric 2D crystal lattice while racemic mixtures show reduced hexatic order with diffusion-like dynamics.
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Affiliation(s)
- Zaiyi Shen
- Univ. Bordeaux, CNRS, LOMA (UMR 5798), F-33405 Talence, France.
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23
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Stability of a Dumbbell Micro-Swimmer. MICROMACHINES 2019; 10:mi10010033. [PMID: 30621046 PMCID: PMC6356347 DOI: 10.3390/mi10010033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 11/20/2018] [Indexed: 12/28/2022]
Abstract
A squirmer model achieves propulsion by generating surface squirming velocities. This model has been used to analyze the movement of micro-swimmers, such as microorganisms and Janus particles. Although squirmer motion has been widely investigated, motions of two connected squirmers, i.e., a dumbbell squirmer, remain to be clarified. The stable assembly of multiple micro-swimmers could be a key technology for future micromachine applications. Therefore, in this study, we investigated the swimming behavior and stability of a dumbbell squirmer. We first examined far-field stability through linear stability analysis, and found that stable forward swimming could not be achieved by a dumbbell squirmer in the far field without the addition of external torque. We then investigated the swimming speed of a dumbbell squirmer connected by a short rigid rod using a boundary element method. Finally, we investigated the swimming stability of a dumbbell squirmer connected by a spring. Our results demonstrated that stable side-by-side swimming can be achieved by pullers. When the aft squirmer was a strong pusher, fore and aft swimming were stable and swimming speed increased significantly. The findings of this study will be useful for the future design of assembled micro-swimmers.
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24
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Semeraro EF, Dattani R, Narayanan T. Microstructure and dynamics of Janus particles in a phase separating medium. J Chem Phys 2018; 148:014904. [PMID: 29306301 DOI: 10.1063/1.5008400] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The evolution of interactions and dynamics of Janus colloidal particles suspended in quasi-binary liquid mixtures undergoing phase separation is presented. The experimental system consisted of silica-nickel Janus particles dispersed in mixtures of 3-methylpyridine, water, and heavy water. Colloidal microstructure and dynamics were probed by ultra-small-angle X-ray scattering and ultra-small-angle X-ray photon correlation spectroscopy, respectively. The observed static and dynamic behaviors are significantly different from those found for Stöber silica colloids in this mixture. The Janus particles manifest a slow aggregation below the coexistence temperature and become strongly attractive upon phase separation of the solvent mixture. In the two-phase region, particles tend to display surfactant-like behavior with silica and nickel surfaces likely preferring water and 3-methylpyridine rich phases, respectively. While the onset of diffusiophoretic motion is evident in the dynamics, it is gradually suppressed by particle clustering at the investigated colloid volume fractions.
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25
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Roy S, Dietrich S, Maciolek A. Solvent coarsening around colloids driven by temperature gradients. Phys Rev E 2018; 97:042603. [PMID: 29758678 DOI: 10.1103/physreve.97.042603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Indexed: 06/08/2023]
Abstract
Using mesoscopic numerical simulations and analytical theory, we investigate the coarsening of the solvent structure around a colloidal particle emerging after a temperature quench of the colloid surface. Qualitative differences in the coarsening mechanisms are found, depending on the composition of the binary liquid mixture forming the solvent and on the adsorption preferences of the colloid. For an adsorptionwise neutral colloid, the phase next to its surface alternates as a function of time. This behavior sets in on the scale of the relaxation time of the solvent and is absent for colloids with strong adsorption preferences. A Janus colloid, with a small temperature difference between its two hemispheres, reveals an asymmetric structure formation and surface enrichment around it, even if the solvent is within its one-phase region and if the temperature of the colloid is above the critical demixing temperature T_{c} of the solvent. Our phenomenological model turns out to capture recent experimental findings according to which, upon laser illumination of a Janus colloid and due to the ensuing temperature gradient between its two hemispheres, the surrounding binary liquid mixture develops a concentration gradient.
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Affiliation(s)
- Sutapa Roy
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - Siegfried Dietrich
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - Anna Maciolek
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland
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26
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Schmidt F, Magazzù A, Callegari A, Biancofiore L, Cichos F, Volpe G. Microscopic Engine Powered by Critical Demixing. PHYSICAL REVIEW LETTERS 2018; 120:068004. [PMID: 29481280 DOI: 10.1103/physrevlett.120.068004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/04/2017] [Indexed: 06/08/2023]
Abstract
We experimentally demonstrate a microscopic engine powered by the local reversible demixing of a critical mixture. We show that, when an absorbing microsphere is optically trapped by a focused laser beam in a subcritical mixture, it is set into rotation around the optical axis of the beam because of the emergence of diffusiophoretic propulsion. This behavior can be controlled by adjusting the optical power, the temperature, and the criticality of the mixture.
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Affiliation(s)
- Falko Schmidt
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
- Soft Matter Lab, Department of Physics and UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
- Peter Debye Institute for Soft Matter Physics, Faculty of Physics and Earth Sciences, Leipzig University, 04103 Leipzig, Germany
| | - Alessandro Magazzù
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
- Soft Matter Lab, Department of Physics and UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
| | - Agnese Callegari
- Soft Matter Lab, Department of Physics and UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
| | - Luca Biancofiore
- Department of Mechanical Engineering, Bilkent University, Ankara 06800, Turkey
| | - Frank Cichos
- Peter Debye Institute for Soft Matter Physics, Faculty of Physics and Earth Sciences, Leipzig University, 04103 Leipzig, Germany
| | - Giovanni Volpe
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
- Soft Matter Lab, Department of Physics and UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
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27
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Tuning the motility and directionality of self-propelled colloids. Sci Rep 2017; 7:14891. [PMID: 29097762 PMCID: PMC5668334 DOI: 10.1038/s41598-017-14126-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/04/2017] [Indexed: 11/11/2022] Open
Abstract
Microorganisms are able to overcome the thermal randomness of their surroundings by harvesting energy to navigate in viscous fluid environments. In a similar manner, synthetic colloidal microswimmers are capable of mimicking complex biolocomotion by means of simple self-propulsion mechanisms. Although experimentally the speed of active particles can be controlled by e.g. self-generated chemical and thermal gradients, an in-situ change of swimming direction remains a challenge. In this work, we study self-propulsion of half-coated spherical colloids in critical binary mixtures and show that the coupling of local body forces, induced by laser illumination, and the wetting properties of the colloid, can be used to finely tune both the colloid’s swimming speed and its directionality. We experimentally and numerically demonstrate that the direction of motion can be reversibly switched by means of the size and shape of the droplet(s) nucleated around the colloid, depending on the particle radius and the fluid’s ambient temperature. Moreover, the aforementioned features enable the possibility to realize both negative and positive phototaxis in light intensity gradients. Our results can be extended to other types of half-coated microswimmers, provided that both of their hemispheres are selectively made active but with distinct physical properties.
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28
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Dattani R, Semeraro EF, Narayanan T. Phoretic motion of colloids in a phase separating medium. SOFT MATTER 2017; 13:2817-2822. [PMID: 28345703 DOI: 10.1039/c6sm02855a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The enhanced motion of dispersed particles driven by a concentration gradient is the basis for diffusiophoresis. Here we present the dynamics of colloids in a phase separating medium probed by X-Ray Photon Correlation Spectroscopy (XPCS) in the ultra-small angle scattering range. Charge stabilized silica colloids suspended in a binary mixture of 3-methylpyridine and water/heavy water are preferentially wetted by 3-methylpyridine and consequently display a phoretic motion towards that phase upon demixing. This activity lasts for hundreds of seconds before the phase separation is complete and the enhanced motion is arrested as the colloids return to normal diffusive dynamics.
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Affiliation(s)
- Rajeev Dattani
- ESRF - The European Synchrotron, 38043 Grenoble, France.
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29
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Illien P, Golestanian R, Sen A. ‘Fuelled’ motion: phoretic motility and collective behaviour of active colloids. Chem Soc Rev 2017; 46:5508-5518. [DOI: 10.1039/c7cs00087a] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Phoretic motility is a propulsion mechanism used to design active particles which display complex collective behaviours, characterised experimentally and theoretically.
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Affiliation(s)
- Pierre Illien
- Rudolf Peierls Centre for Theoretical Physics
- University of Oxford
- Oxford OX1 3NP
- UK
- Department of Chemistry
| | - Ramin Golestanian
- Rudolf Peierls Centre for Theoretical Physics
- University of Oxford
- Oxford OX1 3NP
- UK
| | - Ayusman Sen
- Department of Chemistry
- The Pennsylvania State University
- University Park
- USA
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30
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Intermediate scattering function of an anisotropic active Brownian particle. Sci Rep 2016; 6:36702. [PMID: 27830719 PMCID: PMC5378927 DOI: 10.1038/srep36702] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 10/19/2016] [Indexed: 11/08/2022] Open
Abstract
Various challenges are faced when animalcules such as bacteria, protozoa, algae, or sperms move autonomously in aqueous media at low Reynolds number. These active agents are subject to strong stochastic fluctuations, that compete with the directed motion. So far most studies consider the lowest order moments of the displacements only, while more general spatio-temporal information on the stochastic motion is provided in scattering experiments. Here we derive analytically exact expressions for the directly measurable intermediate scattering function for a mesoscopic model of a single, anisotropic active Brownian particle in three dimensions. The mean-square displacement and the non-Gaussian parameter of the stochastic process are obtained as derivatives of the intermediate scattering function. These display different temporal regimes dominated by effective diffusion and directed motion due to the interplay of translational and rotational diffusion which is rationalized within the theory. The most prominent feature of the intermediate scattering function is an oscillatory behavior at intermediate wavenumbers reflecting the persistent swimming motion, whereas at small length scales bare translational and at large length scales an enhanced effective diffusion emerges. We anticipate that our characterization of the motion of active agents will serve as a reference for more realistic models and experimental observations.
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31
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Lozano C, ten Hagen B, Löwen H, Bechinger C. Phototaxis of synthetic microswimmers in optical landscapes. Nat Commun 2016; 7:12828. [PMID: 27687580 PMCID: PMC5056439 DOI: 10.1038/ncomms12828] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 08/04/2016] [Indexed: 12/25/2022] Open
Abstract
Many microorganisms, with phytoplankton and zooplankton as prominent examples, display phototactic behaviour, that is, the ability to perform directed motion within a light gradient. Here we experimentally demonstrate that sensing of light gradients can also be achieved in a system of synthetic photo-activated microparticles being exposed to an inhomogeneous laser field. We observe a strong orientational response of the particles because of diffusiophoretic torques, which in combination with an intensity-dependent particle motility eventually leads to phototaxis. Since the aligning torques saturate at high gradients, a strongly rectified particle motion is found even in periodic asymmetric intensity landscapes. Our results are in excellent agreement with numerical simulations of a minimal model and should similarly apply to other particle propulsion mechanisms. Because light fields can be easily adjusted in space and time, this also allows to extend our approach to dynamical environments.
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Affiliation(s)
- Celia Lozano
- 2. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart, Germany
- Max-Planck-Institut für Intelligente Systeme, D-70569 Stuttgart, Germany
| | - Borge ten Hagen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Clemens Bechinger
- 2. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart, Germany
- Max-Planck-Institut für Intelligente Systeme, D-70569 Stuttgart, Germany
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32
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Bregulla AP, Würger A, Günther K, Mertig M, Cichos F. Thermo-Osmotic Flow in Thin Films. PHYSICAL REVIEW LETTERS 2016; 116:188303. [PMID: 27203347 DOI: 10.1103/physrevlett.116.188303] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Indexed: 05/07/2023]
Abstract
We report on the first microscale observation of the velocity field imposed by a nonuniform heat content along the solid-liquid boundary. We determine both radial and vertical velocity components of this thermo-osmotic flow field by tracking single tracer nanoparticles. The measured flow profiles are compared to an approximate analytical theory and to numerical calculations. From the measured slip velocity we deduce the thermo-osmotic coefficient for both bare glass and Pluronic F-127 covered surfaces. The value for Pluronic F-127 agrees well with Soret data for polyethylene glycol, whereas that for glass differs from literature values and indicates the complex boundary layer thermodynamics of glass-water interfaces.
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Affiliation(s)
- Andreas P Bregulla
- Molecular Nanophotonics Group, Institute of Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany
| | - Alois Würger
- Laboratoire Ondes et Matière d'Aquitaine, Université de Bordeaux & CNRS, 33405 Talence, France
| | - Katrin Günther
- BioNanotechnology and Structure Formation Group, Department of Chemistry and Food Chemistry, Chair of Physical Chemistry, Measurement and Sensor Technology, Technische Universität Dresden, 01062 Dresden, Germany
| | - Michael Mertig
- BioNanotechnology and Structure Formation Group, Department of Chemistry and Food Chemistry, Chair of Physical Chemistry, Measurement and Sensor Technology, Technische Universität Dresden, 01062 Dresden, Germany
- Kurt-Schwabe-Institut für Mess- und Sensortechnik e.V. Meinsberg, 04736 Waldheim, Germany
| | - Frank Cichos
- Molecular Nanophotonics Group, Institute of Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany
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Würger A. Hydrodynamic Boundary Effects on Thermophoresis of Confined Colloids. PHYSICAL REVIEW LETTERS 2016; 116:138302. [PMID: 27082005 DOI: 10.1103/physrevlett.116.138302] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 06/05/2023]
Abstract
We study hydrodynamic slowing down of a particle moving in a temperature gradient perpendicular to a wall. At distances much smaller than the particle radius, h≪a, the lubrication approximation leads to the reduced velocity u/u_{0}=3(h/a)[ln(a/h)-9/4], where u_{0} is the velocity in the bulk. With Brenner's result for confined diffusion, we find that the trapping efficiency, or effective Soret coefficient, increases logarithmically as the particle gets very close to the wall. Our results provide a quantitative explanation for the recently observed enhancement of thermophoretic trapping at short distances. Our discussion of parallel and perpendicular thermophoresis in a capillary reveals a good agreement with experiments on charged polystyrene particles, and sheds some light on a controversy concerning the size dependence and the nonequilibrium nature of the Soret effect.
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Affiliation(s)
- Alois Würger
- Laboratoire Ondes et Matière d'Aquitaine, Université de Bordeaux & CNRS, 33405 Talence, France
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Samin S, van Roij R. Self-Propulsion Mechanism of Active Janus Particles in Near-Critical Binary Mixtures. PHYSICAL REVIEW LETTERS 2015; 115:188305. [PMID: 26565508 DOI: 10.1103/physrevlett.115.188305] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Indexed: 06/05/2023]
Abstract
Gold-capped Janus particles immersed in a near-critical binary mixture can be propelled using illumination. We employ a nonisothermal diffuse interface approach to investigate the self-propulsion mechanism of a single colloid. We attribute the motion to body forces at the edges of a micronsized droplet that nucleates around the particle. Thus, the often-used concept of a surface velocity cannot account for the self-propulsion. The particle's swimming velocity is related to the droplet shape and size, which is determined by a so-called critical isotherm. Two distinct swimming regimes exist, depending on whether the droplet partially or completely covers the particle. Interestingly, the dependence of the swimming velocity on temperature is nonmonotonic in both regimes.
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Affiliation(s)
- Sela Samin
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - René van Roij
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
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