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Daware SV, Mondal R, Kothari M, Chowdhury A, Liu ACY, Prabhakar R, Kumaraswamy G. Synthesis and Characterization of Monolayer Colloidal Sheets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39288076 DOI: 10.1021/acs.langmuir.4c02262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
Sheet-like colloidal assemblies represent model systems to investigate the structure and properties of two-dimensional materials. Here, we report a simple yet versatile method for the preparation of colloidal monolayer sheet-like assemblies that affords control over the size, crystalline order, flexibility, and defect density. The protocol that we report relies on self-assembly of colloids as a sessile drop of dispersion is evaporated on an oil-covered substrate. In this case, the contact line continually moves as the drop shrinks. Polyethyleneimine polymer-covered micrometer-sized colloidal particles are transported to the air-water interface and assemble to form a monolayer sheet as the drop dries. Cross-linking the polymer renders the colloidal assembly permanent. Interestingly, monodisperse colloidal particles form disordered assemblies when dried from low concentration dispersions, while polycrystalline ordered assemblies form at higher concentrations. We demonstrate that increasing the cross-linker to polymer ratio decreases the flexibility of the assembly. Introduction of different-sized colloidal particles in a sheet leads to increased disorder. Removal of sacrificial particles from the sheet allowed the introduction of "holes" in the sheets. Thus, these colloidal sheets are models for probing the effects of disorder, doping, and vacancies in two-dimensional systems.
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Affiliation(s)
- Santosh Vasant Daware
- Department of Chemical Engineering, Indian Institute of Bombay, Mumbai 400076, India
- IITB Monash Research Academy, IIT Bombay, Powai 400076, India
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3800, Australia
| | - Ranajit Mondal
- Department of Chemical Engineering, IIT Hyderabad, Kandi, Telangana 502284, India
| | - Mansi Kothari
- Department of Chemistry, Indian Institute of Bombay, Mumbai 400076, India
| | - Arindam Chowdhury
- Department of Chemistry, Indian Institute of Bombay, Mumbai 400076, India
| | - Amelia C Y Liu
- School of Physics and Astronomy, Monash University, Clayton 3800, Australia
| | - Ranganathan Prabhakar
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3800, Australia
| | - Guruswamy Kumaraswamy
- Department of Chemical Engineering, Indian Institute of Bombay, Mumbai 400076, India
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Brown NM, VanSaders B, Kronenfeld JM, DeSimone JM, Jaeger HM. Direct measurement of forces in air-based acoustic levitation systems. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:094901. [PMID: 39230560 DOI: 10.1063/5.0225745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Accepted: 08/08/2024] [Indexed: 09/05/2024]
Abstract
Acoustic levitation is frequently used for non-contact manipulation of objects and to study the impact of microgravity on physical and biological processes. While the force field produced by sound pressure lifts particles against gravity (primary acoustic force), multiple levitating objects in the same acoustic cavity interact via forces that arise from scattered sound (secondary acoustic forces). Current experimental techniques for obtaining these force fields are not well-suited for mapping the primary force field at high spatial resolution and cannot directly measure the secondary scattering force. Here, we introduce a method that can measure both acoustic forces in situ, including secondary forces in the near-field limit between arbitrarily shaped, closely spaced objects. Operating similarly to an atomic force microscope, the method inserts into the acoustic cavity a suitably shaped probe tip at the end of a long, flexible cantilever and optically detects its deflection. This makes it possible to measure forces with a resolution better than 50 nN and also to apply stress or strain in a controlled manner to manipulate levitated objects. We demonstrate this by extracting the acoustic potential present in a levitation cavity, directly measuring the acoustic scattering force between two objects, and applying tension to a levitated granular raft of acoustically bound particles in order to obtain the force-displacement curve for its deformation.
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Affiliation(s)
- Nina M Brown
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Bryan VanSaders
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Jason M Kronenfeld
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Joseph M DeSimone
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
| | - Heinrich M Jaeger
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
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Cao D, Yan Z, Cui D, Khan MY, Duan S, Xie G, He Z, Xing DY, Wang W. A Conceptual Framework to Understand the Self-Assembly of Chemically Active Colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:10884-10894. [PMID: 38756056 DOI: 10.1021/acs.langmuir.4c00058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Colloids that generate chemicals, or "chemically active colloids", can interact with their neighbors and generate patterns via forces arising from such chemical gradients. Examples of such assemblies of chemically active colloids are abundant in the literature, but a unified theoretical framework is needed to rationalize the scattered results. Combining experiments, theory, Brownian dynamics, and finite element simulations, we present here a conceptual framework for understanding how immotile, yet chemically active, colloids assemble. This framework is based on the principle of ionic diffusiophoresis and diffusioosmosis and predicts that a chemically active colloid interacts with its neighbors through short- and long-range interactions that can be either repulsive or attractive, depending on the relative diffusivity of the released cations and anions, and the relative zeta potential of a colloidal particle and the planar surface on which it resides. As a result, 4 types of pairwise interactions arise, leading to 4 different types of colloidal assemblies with distinct patterns. Using short-range attraction and long-range attraction (SALR) systems as an example, we show quantitative agreement between the framework and experiments. The framework is then applied to rationalize a wide range of patterns assembled from chemically active colloids in the literature exhibiting other types of pairwise interactions. In addition, the framework can predict what the assembly looks like with minimal experimental information and help infer ionic diffusivity and zeta potential values in systems where these values are inaccessible. Our results represent a solid step toward building a complete theory for understanding and controlling chemically active colloids, from the molecular level to their mesoscopic superstructures and ultimately to the macroscopic properties of the assembled materials.
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Affiliation(s)
- Dezhou Cao
- 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
| | - Donghao Cui
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Mohd Yasir Khan
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shifang Duan
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Guoqiang Xie
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Zikai He
- School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Ding Yu Xing
- School of Civil and Environmental 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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Wu B, VanSaders B, Lim MX, Jaeger HM. Hydrodynamic coupling melts acoustically levitated crystalline rafts. Proc Natl Acad Sci U S A 2023; 120:e2301625120. [PMID: 37428934 PMCID: PMC10629546 DOI: 10.1073/pnas.2301625120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 06/06/2023] [Indexed: 07/12/2023] Open
Abstract
Going beyond the manipulation of individual particles, first steps have recently been undertaken with acoustic levitation in air to investigate the collective dynamical properties of many-body systems self-assembled within the levitation plane. However, these assemblies have been limited to two-dimensional, close-packed rafts where forces due to scattered sound pull particles into direct frictional contact. Here, we overcome this restriction using particles small enough that the viscosity of air establishes a repulsive streaming flow at close range. By tuning the particle size relative to the characteristic length scale for viscous streaming, we control the interplay between attractive and repulsive forces and show how particles can be assembled into monolayer lattices with tunable spacing. While the strength of the levitating sound field does not affect the particles' steady-state separation, it controls the emergence of spontaneous excitations that can drive particle rearrangements in an effectively dissipationless, underdamped environment. Under the action of these excitations, a quiescent particle lattice transitions from a predominantly crystalline structure to a two-dimensional liquid-like state. We find that this transition is characterized by dynamic heterogeneity and intermittency, involving cooperative particle movements that remove the timescale associated with caging for the crystalline lattice. These results shed light on the nature of athermal excitations and instabilities that can arise from strong hydrodynamic coupling among interacting particles.
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Affiliation(s)
- Brady Wu
- Department of Physics, University of Chicago, Chicago, IL60637
- James Franck Institute, University of Chicago, Chicago, IL60637
| | - Bryan VanSaders
- Department of Physics, University of Chicago, Chicago, IL60637
- James Franck Institute, University of Chicago, Chicago, IL60637
| | - Melody X. Lim
- Department of Physics, University of Chicago, Chicago, IL60637
- James Franck Institute, University of Chicago, Chicago, IL60637
| | - Heinrich M. Jaeger
- Department of Physics, University of Chicago, Chicago, IL60637
- James Franck Institute, University of Chicago, Chicago, IL60637
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Chen X, Chen X, Peng Y, Zhu L, Wang W. Dielectrophoretic Colloidal Levitation by Electrode Polarization in Oscillating Electric Fields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6932-6945. [PMID: 37148258 DOI: 10.1021/acs.langmuir.3c00759] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Controlled colloidal levitation is key to many applications. Recently, it was discovered that polymer microspheres were levitated to a few micrometers in aqueous solutions in alternating current (AC) electric fields. A few mechanisms have been proposed to explain this AC levitation such as electrohydrodynamic flows, asymmetric rectified electric fields, and aperiodic electrodiffusiophoresis. Here, we propose an alternative mechanism based on dielectrophoresis in a spatially inhomogeneous electric field gradient extending from the electrode surface micrometers into the bulk. This field gradient is derived from electrode polarization, where counterions accumulate near electrode surfaces. A dielectric microparticle is then levitated from the electrode surface to a height where the dielectrophoretic lift balances gravity. The dielectrophoretic levitation mechanism is supported by two numerical models. One model assumes point dipoles and solves for the Poisson-Nernst-Planck equations, while the second model incorporates a dielectric sphere of a realistic size and permittivity and uses the Maxwell-stress tensor formulation to solve for the electrical body force. In addition to proposing a plausible levitation mechanism, we further demonstrate that AC colloidal levitation can be used to move synthetic microswimmers to controlled heights. This study sheds light on understanding the dynamics of colloidal particles near an electrode and paves the way to using AC levitation to manipulate colloidal particles, active or passive.
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Affiliation(s)
- Xiaowen Chen
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Xi Chen
- 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
| | - Lailai Zhu
- Department of Mechanical Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Wei Wang
- Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
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Sun M, Chan KF, Zhang Z, Wang L, Wang Q, Yang S, Chan SM, Chiu PWY, Sung JJY, Zhang L. Magnetic Microswarm and Fluoroscopy-Guided Platform for Biofilm Eradication in Biliary Stents. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201888. [PMID: 35474246 DOI: 10.1002/adma.202201888] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 04/18/2022] [Indexed: 06/14/2023]
Abstract
Biofilm eradication from medical implants is of fundamental importance, and the treatment of biofilm-associated pathogen infections on inaccessible biliary stents remains challenging. Magnetically driven microrobots with controlled motility, accessibility to the tiny lumen, and swarm enhancement effects can physically disrupt the deleterious biostructures while not developing drug resistance. Magnetic urchin-like capsule robots (MUCRs) loaded with magnetic liquid metal droplets (MLMDs, antibacterial agents) are designed using natural sunflower pollen, and the therapeutic effect of swarming MUCR@MLMDs is explored for eradicating complex mixtures of bacterial biofilm within biliary stents collected from patients. The external magnetic field triggers the emergence of the microswarm and induces MLMDs to transform their shape into spheroids and rods with sharp edges. The inherent natural microspikes of MUCRs and the obtained sharp edges of MLMDs actively rupture the dense biological matrix and multiple species of embedded bacterial cells by exerting mechanical force, finally achieving synergistic biofilm eradication. The microswarm is precisely and rapidly deployed into the biliary stent via endoscopy in 10 min. Notably, fluoroscopy imaging is used to track and navigate the locomotion of microswarm in biliary stents in real-time. The microswarm has great potential for treating bacterial biofilm infections associated with medical implants.
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Affiliation(s)
- Mengmeng Sun
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Kai Fung Chan
- Chow Yuk Ho Technology Center for Innovative Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Multi-Scale Medical Robotics Center, Hong Kong Science Park, Shatin NT, Hong Kong SAR, China
| | - Zifeng Zhang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Lu Wang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
- Multi-Scale Medical Robotics Center, Hong Kong Science Park, Shatin NT, Hong Kong SAR, China
| | - Qinglong Wang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Shihao Yang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | | | - Philip Wai Yan Chiu
- Chow Yuk Ho Technology Center for Innovative Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Multi-Scale Medical Robotics Center, Hong Kong Science Park, Shatin NT, Hong Kong SAR, China
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Joseph Jao Yiu Sung
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Li Zhang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
- Chow Yuk Ho Technology Center for Innovative Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Multi-Scale Medical Robotics Center, Hong Kong Science Park, Shatin NT, Hong Kong SAR, China
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
- CUHK T Stone Robotics Institute, The Chinese University of Hong Kong, Hong Kong, China
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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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