1
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Chen J, Hu J, Kapral R. Chemical Logic Gates on Active Colloids. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2305695. [PMID: 38450886 PMCID: PMC11095161 DOI: 10.1002/advs.202305695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/28/2023] [Indexed: 03/08/2024]
Abstract
Recent studies have shown that active colloidal motors using enzymatic reactions for propulsion hold special promise for applications in fields ranging from biology to material science. It will be desirable to have active colloids with capability of computation so that they can act autonomously to sense their surroundings and alter their own dynamics. It is shown how small chemical networks that make use of enzymatic chemical reactions on the colloid surface can be used to construct motor-based chemical logic gates. The basic features of coupled enzymatic reactions that are responsible for propulsion and underlie the construction and function of chemical gates are described using continuum theory and molecular simulation. Examples are given that show how colloids with specific chemical logic gates, can perform simple sensing tasks. Due to the diverse functions of different enzyme gates, operating alone or in circuits, the work presented here supports the suggestion that synthetic motors using such gates could be designed to operate in an autonomous way in order to complete complicated tasks.
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Affiliation(s)
- Jiang‐Xing Chen
- Department of PhysicsHangzhou Normal UniversityHangzhou311121China
| | - Jia‐Qi Hu
- Department of PhysicsHangzhou Normal UniversityHangzhou311121China
| | - Raymond Kapral
- Chemical Physics Theory GroupDepartment of ChemistryUniversity of TorontoTorontoOntarioM5S 3H6Canada
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2
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Cui D, Yan Z, Chen X, Liu J, Wang W. Electroosmotic flow spin tracers near chemical nano/micromotors. NANOSCALE 2024; 16:2847-2851. [PMID: 38258465 DOI: 10.1039/d3nr05910c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
We report the first experimental observation of tracer spinning in place alongside chemically powered individual nano/micromotors. The torques are primarily generated by the electroosmotic flow on the motor surface. Such spinning is observed in various combinations of nano/micromotors and tracers of different shapes, sizes and chemical compositions.
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Affiliation(s)
- Donghao Cui
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China.
| | - Zuyao Yan
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China.
| | - Xiaowen Chen
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China.
| | - Jiayu Liu
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China.
| | - Wei Wang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China.
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3
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Becton M, Hou J, Zhao Y, Wang X. Dynamic Clustering and Scaling Behavior of Active Particles under Confinement. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:144. [PMID: 38251109 PMCID: PMC10819351 DOI: 10.3390/nano14020144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/05/2024] [Accepted: 01/07/2024] [Indexed: 01/23/2024]
Abstract
A systematic investigation of the dynamic clustering behavior of active particles under confinement, including the effects of both particle density and active driving force, is presented based on a hybrid coarse-grained molecular dynamics simulation. First, a series of scaling laws are derived with power relationships for the dynamic clustering time as a function of both particle density and active driving force. Notably, the average number of clusters N¯ assembled from active particles in the simulation system exhibits a scaling relationship with clustering time t described by N¯∝t-m. Simultaneously, the scaling behavior of the average cluster size S¯ is characterized by S¯∝tm. Our findings reveal the presence of up to four distinct dynamic regions concerning clustering over time, with transitions contingent upon the particle density within the system. Furthermore, as the active driving force increases, the aggregation behavior also accelerates, while an increase in density of active particles induces alterations in the dynamic procession of the system.
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Affiliation(s)
- Matthew Becton
- School of ECAM, College of Engineering, University of Georgia, Athens, GA 30602, USA; (M.B.); (J.H.)
| | - Jixin Hou
- School of ECAM, College of Engineering, University of Georgia, Athens, GA 30602, USA; (M.B.); (J.H.)
| | - Yiping Zhao
- Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA;
| | - Xianqiao Wang
- School of ECAM, College of Engineering, University of Georgia, Athens, GA 30602, USA; (M.B.); (J.H.)
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4
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Saintillan D. Dispersion of run-and-tumble microswimmers through disordered media. Phys Rev E 2023; 108:064608. [PMID: 38243487 DOI: 10.1103/physreve.108.064608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 11/20/2023] [Indexed: 01/21/2024]
Abstract
Understanding the transport properties of microorganisms and self-propelled particles in porous media has important implications for human health as well as microbial ecology. In free space, most microswimmers perform diffusive random walks as a result of the interplay of self-propulsion and orientation decorrelation mechanisms such as run-and-tumble dynamics or rotational diffusion. In an unstructured porous medium, collisions with the microstructure result in a decrease in the effective spatial diffusivity of the particles from its free-space value. Here, we analyze this problem for a simple model system consisting of noninteracting point particles performing run-and-tumble dynamics through a two-dimensional disordered medium composed of a random distribution of circular obstacles, in the absence of Brownian diffusion or hydrodynamic interactions. The particles are assumed to collide with the obstacles as hard spheres and subsequently slide on the obstacle surface with no frictional resistance while maintaining their orientation, until they either escape or tumble. We show that the variations in the long-time diffusivity can be described by a universal dimensionless hindrance function f(ϕ,Pe) of the obstacle area fraction ϕ and Péclet number Pe, or ratio of the swimmer run length to the obstacle size. We analytically derive an asymptotic expression for the hindrance function valid for dilute media (Peϕ≪1), and its extension to denser media is obtained using stochastic simulations. As we explain, the model is also easily generalized to describe dispersion in three dimensions.
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Affiliation(s)
- David Saintillan
- Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
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5
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Chen X, Chen X, Elsayed M, Edwards H, Liu J, Peng Y, Zhang HP, Zhang S, Wang W, Wheeler AR. Steering Micromotors via Reprogrammable Optoelectronic Paths. ACS NANO 2023; 17:5894-5904. [PMID: 36912818 DOI: 10.1021/acsnano.2c12811] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Steering micromotors is important for using them in practical applications and as model systems for active matter. This functionality often requires magnetic materials in the micromotor, taxis behavior of the micromotor, or the use of specifically designed physical boundaries. Here, we develop an optoelectronic strategy that steers micromotors with programmable light patterns. In this strategy, light illumination turns hydrogenated amorphous silicon conductive, generating local electric field maxima at the edge of the light pattern that attracts micromotors via positive dielectrophoresis. As an example, metallo-dielectric Janus microspheres that self-propelled under alternating current electric fields were steered by static light patterns along customized paths and through complex microstructures. Their long-term directionality was also rectified by ratchet-shaped light patterns. Furthermore, dynamic light patterns that varied in space and time enabled more advanced motion controls such as multiple motion modes, parallel control of multiple micromotors, and the collection and transport of motor swarms. This optoelectronic steering strategy is highly versatile and compatible with a variety of micromotors, and thus it possesses the potential for their programmable control in complex environments.
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Affiliation(s)
- Xi Chen
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3E1, Canada
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Canada
| | - Xiaowen Chen
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Mohamed Elsayed
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3E1, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Canada
| | - Harrison Edwards
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3E1, Canada
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Canada
| | - Jiayu Liu
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Yixin Peng
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - H P Zhang
- School of Physics and Astronomy and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shuailong Zhang
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing 100081, China
| | - Wei Wang
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Aaron R Wheeler
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3E1, Canada
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Canada
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6
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Antunes GC, Malgaretti P, Harting J, Dietrich S. Pumping and Mixing in Active Pores. PHYSICAL REVIEW LETTERS 2022; 129:188003. [PMID: 36374705 DOI: 10.1103/physrevlett.129.188003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
We show both numerically and analytically that a chemically patterned active pore can act as a micro- or nanopump for fluids, even if it is fore-aft symmetric. This is possible due to a spontaneous symmetry breaking which occurs when advection rather than diffusion is the dominant mechanism of solute transport. We further demonstrate that, for pumping and tuning the flow rate, a combination of geometrical and chemical inhomogeneities is required. For certain parameter values, the flow is unsteady, and persistent oscillations with a tunable frequency appear. Finally, we find that the flow exhibits convection rolls and hence promotes mixing in the low Reynolds number regime.
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Affiliation(s)
- G C Antunes
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
- Helmholtz-Institut Erlangen-Nürnberg für Erneuerbare Energien (IEK-11), Forschungszentrum Jülich, Cauerstraße 1, 91058 Erlangen, Germany
| | - P Malgaretti
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
- Helmholtz-Institut Erlangen-Nürnberg für Erneuerbare Energien (IEK-11), Forschungszentrum Jülich, Cauerstraße 1, 91058 Erlangen, Germany
| | - J Harting
- Helmholtz-Institut Erlangen-Nürnberg für Erneuerbare Energien (IEK-11), Forschungszentrum Jülich, Cauerstraße 1, 91058 Erlangen, Germany
- Department Chemie-und Bioingenieurwesen und Department Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fürther Straße 248, 90429 Nürnberg, Germany
| | - S Dietrich
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
- IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
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7
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Nizkaya TV, Asmolov ES, Vinogradova OI. Theoretical modeling of catalytic self-propulsion. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101637] [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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8
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Active Colloids on Fluid Interfaces. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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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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10
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Boymelgreen A, Schiffbauer J, Khusid B, Yossifon G. Synthetic electrically driven colloids: a platform for understanding collective behavior in soft matter. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Singh K, Yadav A, Dwivedi P, Mangal R. Interaction of Active Janus Colloids with Tracers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2686-2698. [PMID: 35166106 DOI: 10.1021/acs.langmuir.1c03424] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Understanding the motion of artificial active swimmers in complex surroundings, such as a dense bath of passive particulate matter, is essential for their successful utilization as cargo (drug) carriers and sensors or for medical imaging, under microscopic domains. In this study, we experimentally investigated the motion of active SiO2-Pt Janus particles (JPs) in a two-dimensional bath of smaller silica tracers dispersed with varying areal densities. Our observations indicate that when an active JP undergoes a collision with an isolated tracer, their interaction can have a significant impact on the swimmer's motion. However, the overall impact of tracers on the active JPs' motion (translation and rotation) depends on the frequency of collisions and also on the nature of the collision, which is marked by the time-duration for which the particles maintain contact during the collisions. Further, in the high-density tracer bath, our experiments reveal that the motion of the active JP results in a novel organizational behavior of the tracers on the trailing Pt (depletion of tracers) and the leading SiO2 (accumulation of tracers) side. In laboratory frame the emergence and the subsequent vanishing of the depletion zone are discussed in detail.
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Affiliation(s)
- Karnika Singh
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Ankit Yadav
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Prateek Dwivedi
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Rahul Mangal
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
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12
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Feuerstein L, Biermann CG, Xiao Z, Holm C, Simmchen J. Highly Efficient Active Colloids Driven by Galvanic Exchange Reactions. J Am Chem Soc 2021; 143:17015-17022. [PMID: 34523911 DOI: 10.1021/jacs.1c06400] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Micromotors are propelled by a variety of chemical reactions, with most of them being of catalytic nature. There are, however, systems based on redox reactions, which show clear benefits for efficiency. Here, we broaden the spectrum of suitable reactions to galvanic exchange processes, or an electrochemical replacement of a solid metal layer with dissolved ionic species of a more noble metal. We study the details of motility and the influence of different reaction parameters to conclude that these galvanophoretic processes circumvent several steps that lose efficiency in catalytic micromotors. Furthermore, we investigate the chemical process, the charge, and flow conditions that lead to this highly efficient new type of active motility. Toward a better understanding of the underlying processes, we propose an electrokinetic model that we numerically solve via finite elements.
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Affiliation(s)
- Linda Feuerstein
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Carl Georg Biermann
- Institute for Computational Physics (ICP), Allmandring 3, 70569 Stuttgart, Germany
| | - Zuyao Xiao
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Christian Holm
- Institute for Computational Physics (ICP), Allmandring 3, 70569 Stuttgart, Germany
| | - Juliane Simmchen
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
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13
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Choudhary A, Chaithanya KVS, Michelin S, Pushpavanam S. Self-propulsion in 2D confinement: phoretic and hydrodynamic interactions. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:97. [PMID: 34283325 DOI: 10.1140/epje/s10189-021-00101-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Chemically active Janus particles generate tangential concentration gradients along their surface for self-propulsion. Although this is well studied in unbounded domains, the analysis in biologically relevant environments such as confinement is scarce. In this work, we study the motion of a Janus sphere in weak confinement. The particle is placed at an arbitrary location, with arbitrary orientation between the two walls. Using the method of reflections, we study the effect of confining planar boundaries on the phoretic and hydrodynamic interactions, and their consequence on the Janus particle dynamics. The dynamical trajectories are analyzed using phase diagrams for different surface coverage of activity and solute-particle interactions. In addition to near wall states such as 'sliding' and 'hovering', we demonstrate that accounting for two planar boundaries reveals two new states: channel-spanning oscillations and damped oscillations around the centerline, which were characterized as 'scattering' or 'reflection' by earlier analyses on single wall interactions. Using phase-diagrams, we highlight the differences in inert-facing and active-facing Janus particles. We also compare the dynamics of Janus particles with squirmers for contrasting the chemical interactions with hydrodynamic effects. Insights from the current work suggest that biological and artificial swimmers sense their surroundings through long-ranged interactions, that can be modified by altering the surface properties.
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Affiliation(s)
- Akash Choudhary
- Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Institute of Theoretical Physics, Technische Universität Berlin, 10623, Berlin, Germany
| | - K V S Chaithanya
- Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
| | - Sébastien Michelin
- LadHyX, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91120, Palaiseau, France
| | - S Pushpavanam
- Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India.
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14
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Katuri J, Uspal WE, Popescu MN, Sánchez S. Inferring non-equilibrium interactions from tracer response near confined active Janus particles. SCIENCE ADVANCES 2021; 7:7/18/eabd0719. [PMID: 33931441 PMCID: PMC8087409 DOI: 10.1126/sciadv.abd0719] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 03/12/2021] [Indexed: 05/02/2023]
Abstract
Chemically active Janus particles sustain non-equilibrium spatial variations in the chemical composition of the suspending solution; these induce hydrodynamic flow and (self-)motility of the particles. Direct mapping of these fields has so far proven to be too challenging. Therefore, indirect methods are needed, e.g., deconvolving the response of "tracer" particles to the activity-induced fields. Here, we study experimentally the response of silica particles, sedimented at a wall, to active Pt/silica Janus particles. The latter are either immobilized at the wall, with the symmetry axis perpendicular or parallel to the wall, or motile. The experiments reveal complex effective interactions that are dependent on the configuration and on the state of motion of the active particle. Within the framework of a coarse-grained model, the behavior of tracers near an immobilized Janus particle can be captured qualitatively once activity-induced osmotic flows on the wall are considered.
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Affiliation(s)
- Jaideep Katuri
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10-12, 08028 Barcelona Spain.
| | - William E Uspal
- Department of Mechanical Engineering, University of Hawaii at Manoa, 2540 Dole Street, Holmes Hall 302, Honolulu, HI 96822, USA.
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
| | - Mihail N Popescu
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany.
| | - Samuel Sánchez
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10-12, 08028 Barcelona Spain.
- Institució Catalana de Recerca i Estudis Avancats (ICREA), Pg. Lluís Companys 23, 08010 Bacelona, Spain
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15
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Wittmann M, Popescu MN, Domínguez A, Simmchen J. Active spheres induce Marangoni flows that drive collective dynamics. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:15. [PMID: 33683489 PMCID: PMC7940161 DOI: 10.1140/epje/s10189-020-00006-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/21/2020] [Indexed: 05/26/2023]
Abstract
For monolayers of chemically active particles at a fluid interface, collective dynamics is predicted to arise owing to activity-induced Marangoni flow even if the particles are not self-propelled. Here, we test this prediction by employing a monolayer of spherically symmetric active [Formula: see text] particles located at an oil-water interface with or without addition of a nonionic surfactant. Due to the spherical symmetry, an individual particle does not self-propel. However, the gradients produced by the photochemical fuel degradation give rise to long-ranged Marangoni flows. For the case in which surfactant is added to the system, we indeed observe the emergence of collective motion, with dynamics dependent on the particle coverage of the monolayer. The experimental observations are discussed within the framework of a simple theoretical mean-field model.
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Affiliation(s)
- Martin Wittmann
- Technical University Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Mihail N. Popescu
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Alvaro Domínguez
- Física Teórica, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla, Spain
- Instituto Carlos I de Física Teórica y Computacional, 18071 Granada, Spain
| | - Juliane Simmchen
- Technical University Dresden, Zellescher Weg 19, 01069 Dresden, Germany
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16
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Duan Y, Zhao X, Sun M, Hao H. Research Advances in the Synthesis, Application, Assembly, and Calculation of Janus Materials. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.0c04304] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Xia Zhao
- School of Chemical Engineering, Northwest University, Xi’an 710069, Shan xi, China
| | - Miaomiao Sun
- School of Chemical Engineering, Northwest University, Xi’an 710069, Shan xi, China
| | - Hong Hao
- School of Chemical Engineering, Northwest University, Xi’an 710069, Shan xi, China
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17
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Ketzetzi S, de Graaf J, Kraft DJ. Diffusion-Based Height Analysis Reveals Robust Microswimmer-Wall Separation. PHYSICAL REVIEW LETTERS 2020; 125:238001. [PMID: 33337216 DOI: 10.1103/physrevlett.125.238001] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/08/2020] [Indexed: 06/12/2023]
Abstract
Microswimmers typically move near walls, which can strongly influence their motion. However, direct experimental measurements of swimmer-wall separation remain elusive to date. Here, we determine this separation for model catalytic microswimmers from the height dependence of the passive component of their mean-squared displacement. We find that swimmers exhibit "ypsotaxis," a tendency to assume a fixed height above the wall for a range of salt concentrations, swimmer surface charges, and swimmer sizes. Our findings indicate that ypsotaxis is activity induced, posing restrictions on future modeling of their still-debated propulsion mechanism.
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Affiliation(s)
- Stefania Ketzetzi
- Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, Netherlands
| | - Joost de Graaf
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, Netherlands
| | - Daniela J Kraft
- Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, Netherlands
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18
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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.
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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
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19
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Xiao Z, Duan S, Xu P, Cui J, Zhang H, Wang W. Synergistic Speed Enhancement of an Electric-Photochemical Hybrid Micromotor by Tilt Rectification. ACS NANO 2020; 14:8658-8667. [PMID: 32530617 DOI: 10.1021/acsnano.0c03022] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A hybrid micromotor is an active colloid powered by more than one power source, often exhibiting expanded functionality and controllability than those of a singular energy source. However, these power sources are often applied orthogonally, leading to stacked propulsion that is just a sum of two independent mechanisms. Here, we report that TiO2-Pt Janus micromotors, when subject to both UV light and AC electric fields, move up to 90% faster than simply adding up the speed powered by either source. This unexpected synergy between light and electric fields, we propose, arises from the fact that an electrokinetically powered TiO2-Pt micromotor moves near a substrate with a tilted Janus interface that, upon the application of an electric field, becomes rectified to be vertical to the substrate. Control experiments with magnetic fields and three types of micromotors unambiguously and quantitatively show that the tilting angle of a micromotor correlates positively with its instantaneous speed, reaching maximum at a vertical Janus interface. Such "tilting-induced retardation" could affect a wide variety of chemically powered micromotors, and our findings are therefore helpful in understanding the dynamics of micromachines in confinement.
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Affiliation(s)
- Zuyao Xiao
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Shifang Duan
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Pengzhao Xu
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Jingqin Cui
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, China
| | - Hepeng Zhang
- School of Physics and Astronomy and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Wei Wang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
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20
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Xu P, Duan S, Xiao Z, Yang Z, Wang W. Light-powered active colloids from monodisperse and highly tunable microspheres with a thin TiO 2 shell. SOFT MATTER 2020; 16:6082-6090. [PMID: 32568346 DOI: 10.1039/d0sm00719f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The emerging field of active matter, and its subset active colloid, is in great need of good model systems consisting of moving entities that are uniform and highly tunable. In this article, we address this challenge by introducing core-shell SiO2-TiO2 microspheres, prepared by chemically coating a thin layer of TiO2 on an inert core, that are highly monodisperse in size (polydispersity 4.1%) and regular in shape (circularity 0.93). Compared with similar samples prepared by the classic sol-gel method, Janus TiO2-Pt active colloids prepared with core-shell TiO2 spheres move faster and boast a much clearer Janus interface. Moreover, a unique feature of these core-shell TiO2 microspheres is their great tunability in the colloid size, shell thickness, and even the type of the core particle. These advantages are highlighted in two examples, one demonstrating a TiO2-Pt active colloid with a magnetic core that enables magnetic manipulation, and the other demonstrating the collective expansion and contraction of a uniform cluster of core-shell TiO2 colloids under UV light illumination. We believe that TiO2 microspheres produced by this core-shell technique compare favorably with many other types of active colloids being employed as model systems, and thus open up many research possibilities.
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Affiliation(s)
- Pengzhao Xu
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
| | - Shifang Duan
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
| | - Zuyao Xiao
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
| | - Zhou Yang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
| | - Wei Wang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
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21
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Das S, Jalilvand Z, Popescu MN, Uspal WE, Dietrich S, Kretzschmar I. Floor- or Ceiling-Sliding for Chemically Active, Gyrotactic, Sedimenting Janus Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:7133-7147. [PMID: 31986887 PMCID: PMC7331144 DOI: 10.1021/acs.langmuir.9b03696] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/27/2020] [Indexed: 05/18/2023]
Abstract
Chemically active particles achieve motility without external forces and torques ("self-propulsion") due to catalytic chemical reactions at their surfaces, which change the chemical composition of the surrounding solution (called "chemical field") and induce hydrodynamic flow of the solution. By coupling the distortions of these fields back to its motion, a chemically active particle experiences an effective interaction with confining surfaces. This coupling can lead to a rich behavior, such as the occurrence of wall-bound steady states of "sliding". Most active particles are density mismatched with the solution and, thus, tend to sediment. Moreover, the often employed Janus spheres, which consist of an inert core material decorated with a cap-like, thin layer of a catalyst, are gyrotactic (i.e., "bottom-heavy"). Whether or not they may exhibit sliding states at horizontal walls depends on the interplay between the active motion and the gravity-driven sedimentation and alignment, such as the gyrotactic tendency to align the axis along the gravity direction being overcome by a competing, activity-driven alignment with a different orientation. It is therefore important to understand and quantify the influence of these gravity-induced effects on the behavior of model chemically active particles moving in the vicinity of walls. For model gyrotactic, self-phoretic Janus particles, here we study theoretically the occurrence of sliding states at horizontal planar walls that are either below ("floor") or above ("ceiling") the particle. We construct "state diagrams" characterizing the occurrence of such states as a function of the sedimentation velocity and of the gyrotactic response of the particle, as well as of the phoretic mobility of the particle. We show that in certain cases sliding states may emerge simultaneously at both the ceiling and the floor, while the larger part of the experimentally relevant parameter space corresponds to particles that would exhibit sliding states only either at the floor or at the ceiling-or there are no sliding states at all. These predictions are critically compared with the results of previous experimental studies, as well as with our dedicated experiments carried out with Pt-coated, polystyrene-core, or silica-core Janus spheres immersed in aqueous hydrogen peroxide solutions.
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Affiliation(s)
- Sayan Das
- Max-Planck-Institut
für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
| | - Zohreh Jalilvand
- Department
of Chemical Engineering, City College of
the City University of New York (CUNY), 140th Street and Convent Avenue, New York, New York 10031, United States
| | - Mihail N. Popescu
- Max-Planck-Institut
für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
| | - William E. Uspal
- Department
of Mechanical Engineering, University of
Hawai’i at Ma̅noa, 2540 Dole Street, Holmes Hall
302, Honolulu, Hawai’i 96822, United States
| | - Siegfried Dietrich
- Max-Planck-Institut
für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart, Germany
- IV.
Institut für Theoretische
Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Ilona Kretzschmar
- Department
of Chemical Engineering, City College of
the City University of New York (CUNY), 140th Street and Convent Avenue, New York, New York 10031, United States
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22
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Jalilvand Z, Haider H, Cui J, Kretzschmar AI. Pt-SiO 2 Janus Particles and the Water/Oil Interface: A Competition between Motility and Thermodynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6880-6887. [PMID: 32050073 DOI: 10.1021/acs.langmuir.9b03454] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Various aspects of the behavior of Janus particles near liquid/liquid interfaces have been studied through different experimental and theoretical realizations, but the effect of motility on the behavior of Janus particles near liquid/liquid interfaces has not been investigated, yet. Here, we demonstrate the ability to engineer the behavior of highly interfacial active Janus particles near a water/oil interface by introducing motility to the system. Passive, i.e., nonmotile, platinum-capped 8 μm silica (Pt-SiO2) Janus particles exhibit a strong tendency to attach to water/oil interfaces with the Pt-cap facing the oil and the SiO2 side facing the water phase. In contrast, we show that active, i.e., motile, 8 μm Pt-SiO2 Janus particles approach the interface, orient in a sideways fashion with the Janus boundary perpendicular to the interface, and then swim in the vicinity of the interface similar to observations reported near solid/liquid interfaces. Active Pt-SiO2 Janus particles near the water/oil interface show motility as a result of adding H2O2 to the particle solution. The decomposition of H2O2 into O2 and H2O creates a nonuniform gradient of O2 around the particle that hydrodynamically interacts with the water/decalin boundary. The interaction enables rotation of the particle within the swimming plane that is parallel to the interface but restricts rotation in and out of the swimming plane, thereby preventing adsorption to the liquid/liquid interface.
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Affiliation(s)
- Zohreh Jalilvand
- Department of Chemical Engineering, The City College of New York, New York , New York 10031, United States
| | - Hamad Haider
- Department of Chemical Engineering, The City College of New York, New York , New York 10031, United States
| | - Jingqin Cui
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, Fujian 361005, PR China
| | - And Ilona Kretzschmar
- Department of Chemical Engineering, The City College of New York, New York , New York 10031, United States
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23
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Popescu MN. Chemically Active Particles: From One to Few on the Way to Many. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6861-6870. [PMID: 32233489 PMCID: PMC7331135 DOI: 10.1021/acs.langmuir.9b03973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 04/01/2020] [Indexed: 06/01/2023]
Abstract
Chemically active particles suspended in a liquid solution can achieve self-motility by locally changing the chemical composition of the solution via catalytic reactions at their surfaces. They operate intrinsically out of equilibrium, continuously extracting free energy from the environment to power the dissipative self-motility. The effective interactions involving active particles are, in general, nonreciprocal and anisotropic, even if the particles have simple shapes (e.g., Janus spheres). Accordingly, for chemically active particles a very rich behavior of collective motion and self-assembly may be expected to emerge, including phenomena such as microphase separation in the form of kinetically stable, finite-sized aggregates. Here, I succinctly review a number of recent experimental studies that demonstrate the self-assembly of structures, involving chemically active Janus particles, which exhibit various patterns of motion. These examples illustrate concepts such as "motors made out of motors" (as suggestively named by Fischer [Fischer, P. Nat. Phys. 2018, 14, 1072]). The dynamics of assembly and structure formation observed in these systems can provide benchmark, in-depth testing of the current understanding of motion and effective interactions produced by chemical activity. Finally, one notes that these significant achievements are likely just the beginning of the field. Recently reported particles endowed with time-dependent chemical activity or switchable reaction mechanisms open the way for exciting developments, such as periodic reshaping of self-assembled structures based on man-made internal clocks.
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24
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Wang W, Lv X, Moran JL, Duan S, Zhou C. A practical guide to active colloids: choosing synthetic model systems for soft matter physics research. SOFT MATTER 2020; 16:3846-3868. [PMID: 32285071 DOI: 10.1039/d0sm00222d] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Synthetic active colloids that harvest energy stored in the environment and swim autonomously are a popular model system for active matter. This emerging field of research sits at the intersection of materials chemistry, soft matter physics, and engineering, and thus cross-talk among researchers from different backgrounds becomes critical yet difficult. To facilitate this interdisciplinary communication, and to help soft matter physicists with choosing the best model system for their research, we here present a tutorial review article that describes, in appropriate detail, six experimental systems of active colloids commonly found in the physics literature. For each type, we introduce their background, material synthesis and operating mechanisms and notable studies from the soft matter community, and comment on their respective advantages and limitations. In addition, the main features of each type of active colloid are summarized into two useful tables. As materials chemists and engineers, we intend for this article to serve as a practical guide, so those who are not familiar with the experimental aspects of active colloids can make more informed decisions and maximize their creativity.
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Affiliation(s)
- Wei Wang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, China.
| | - Xianglong Lv
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, China.
| | - Jeffrey L Moran
- Department of Mechanical Engineering, George Mason University, Fairfax, USA
| | - Shifang Duan
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, China.
| | - Chao Zhou
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, China.
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25
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Farahmand Bafi N, Nowakowski P, Dietrich S. Effective pair interaction of patchy particles in critical fluids. J Chem Phys 2020; 152:114902. [PMID: 32199445 DOI: 10.1063/5.0001293] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We study the critical Casimir interaction between two spherical colloids immersed in a binary liquid mixture close to its critical demixing point. The surface of each colloid prefers one species of the mixture with the exception of a circular patch of arbitrary size, where the other species is preferred. For such objects, we calculate, within the Derjaguin approximation, the scaling function describing the critical Casimir potential, and we use it to derive the scaling functions for all components of the forces and torques acting on both colloids. The results are compared with available experimental data. Moreover, the general relation between the scaling function for the potential and the scaling functions for the force and the torque is derived.
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Affiliation(s)
- N Farahmand Bafi
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany and Institut für Theoretische Physik IV, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - P Nowakowski
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany and Institut für Theoretische Physik IV, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - S Dietrich
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany and Institut für Theoretische Physik IV, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
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26
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Chen X, Zhou C, Peng Y, Wang Q, Wang W. Temporal Light Modulation of Photochemically Active, Oscillating Micromotors: Dark Pulses, Mode Switching, and Controlled Clustering. ACS APPLIED MATERIALS & INTERFACES 2020; 12:11843-11851. [PMID: 32092253 DOI: 10.1021/acsami.9b22342] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photochemically powered micromotors are prototype microrobots, and spatiotemporal control is pivotal for a wide range of potential applications. Although their spatial navigation has been extensively studied, temporal control of photoactive micromotors remains much less explored. Using Ag-based oscillating micromotors as a model system, a strategy is presented for the controlled modulation of their individual and collective dynamics via periodically switching illumination on and off. In particular, such temporal light modulation drives individual oscillating micromotors into a total of six regimes of distinct dynamics, as the light-toggling frequencies vary from 0 to 103 Hz. On an ensemble level, toggling light at 5 Hz gives rise to controlled, reversible clustering of oscillating micromotors and self-assembly of tracer microspheres into colloidal crystals. A qualitative mechanism based on Ag-catalyzed decomposition of H2O2 is given to account for some, but not all, of the above observations. This study might potentially inspire more sophisticated temporal control of micromotors and the development of smart, biomimetic materials that respond to environmental stimuli that not only change in space but also in time.
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Affiliation(s)
- Xi Chen
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Chao Zhou
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Yixin Peng
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Qizhang Wang
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Wei Wang
- Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
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27
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Ketzetzi S, de Graaf J, Doherty RP, Kraft DJ. Slip Length Dependent Propulsion Speed of Catalytic Colloidal Swimmers near Walls. PHYSICAL REVIEW LETTERS 2020; 124:048002. [PMID: 32058791 DOI: 10.1103/physrevlett.124.048002] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 09/06/2019] [Indexed: 06/10/2023]
Abstract
Catalytic colloidal swimmers that propel due to self-generated fluid flows exhibit strong affinity for surfaces. Here, we report experimental measurements of a significant dependence of such microswimmers' speed on the nearby substrate material. We find that speeds scale with the solution contact angle θ on the substrate, which relates to the associated hydrodynamic substrate slip length, as V∝(cosθ+1)^{-3/2}. We show that such dependence can be attributed to osmotic coupling between swimmers and substrate. Our work points out that hydrodynamic slip at nearby walls, though often unconsidered, can significantly impact microswimmer self-propulsion.
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Affiliation(s)
- Stefania Ketzetzi
- Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Joost de Graaf
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Rachel P Doherty
- Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Daniela J Kraft
- Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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28
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Issa M, Baumgartner NR, Kalil MA, Ryan SD, Wirth CL. Charged Nanoparticles Quench the Propulsion of Active Janus Colloids. ACS OMEGA 2019; 4:13034-13041. [PMID: 31460430 PMCID: PMC6705040 DOI: 10.1021/acsomega.9b00765] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
Active colloidal particles regularly interact with surfaces in applications ranging from microfluidics to sensing. Recent work has revealed the complex nature of these surface interactions for active particles. Herein, we summarize experiments and simulations that show the impact of charged nanoparticles on the propulsion of an active colloid near a boundary. Adding charged nanoparticles not only decreased the average separation distance of a passive colloid because of depletion attraction as expected but also decreased the apparent propulsion of a Janus colloid to near zero. Complementary agent-based simulations considering the impact of hydrodynamics for active Janus colloids were conducted in the range of separation distances inferred from experiment. These simulations showed that propulsion speed decreased monotonically with decreasing average separation distance. Although the trend found in experiments and simulations was in qualitative agreement, there was still a significant difference in the magnitude of speed reduction. The quantitative difference was attributed to the influence of charged nanoparticles on the conductivity of the active particle suspension. Follow-up experiments delineating the impact of depletion and conductivity showed that both contribute to the reduction of speed for an active Janus particle. The experimental and simulated data suggests that it is necessary to consider the synergistic effects between various mechanisms influencing interactions experienced by an active particle near a boundary.
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Affiliation(s)
- Marola
W. Issa
- Department
of Chemical and Biomedical Engineering, Washkewicz College
of Engineering and Department of Mathematics and Statistics, College of Science and
Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115, United States
| | - Nicky R. Baumgartner
- Department
of Chemical and Biomedical Engineering, Washkewicz College
of Engineering and Department of Mathematics and Statistics, College of Science and
Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115, United States
| | - Mohammed A. Kalil
- Department
of Chemical and Biomedical Engineering, Washkewicz College
of Engineering and Department of Mathematics and Statistics, College of Science and
Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115, United States
| | - Shawn D. Ryan
- Department
of Chemical and Biomedical Engineering, Washkewicz College
of Engineering and Department of Mathematics and Statistics, College of Science and
Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115, United States
| | - Christopher L. Wirth
- Department
of Chemical and Biomedical Engineering, Washkewicz College
of Engineering and Department of Mathematics and Statistics, College of Science and
Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115, United States
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