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Rahat SA, Chaudhuri K, Pham JT. Capillary detachment of a microparticle from a liquid-liquid interface. SOFT MATTER 2023; 19:6247-6254. [PMID: 37555264 DOI: 10.1039/d3sm00470h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
The attachment and detachment of microparticles at a liquid-liquid interface are common in many material systems, from Pickering emulsions and colloidal assemblies to capillary suspensions. Properties of these systems rely on how the particles interact with the liquid-liquid interface, including the detachment process. In this study, we simultaneously measure the capillary detachment force of a microparticle from a liquid-liquid interface and visualize the shape of the meniscus by combining colloidal probe microscopy and confocal microscopy. The capillary behavior is studied on both untreated (hydrophilic) and fluorinated (hydrophobic) glass microparticles. The measured force data show good agreement with theoretical calculations based on the extracted geometric parameters from confocal images of the capillary bridge. It is also evident that contact line pinning is an important aspect of detachment for both untreated and fluorinated particles.
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Affiliation(s)
- Sazzadul A Rahat
- Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221, USA.
| | - Krishnaroop Chaudhuri
- Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Jonathan T Pham
- Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221, USA.
- Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA
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2
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Hazra S, Mitra S, Sen AK. Migration and Spreading of Droplets across a Fluid-Fluid Interface in Microfluidic Coflow. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9660-9668. [PMID: 35876791 DOI: 10.1021/acs.langmuir.2c01260] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Interfacial migration of droplets in microfluidic confinements has significant relevance in cell biology and biochemical assays. So far, studies on passive interfacial migration of droplets are limited to co-flow interfaces having small interfacial tension (IFT ∼ 1 mN/m). Here, we elucidate the migration and spreading of droplets (SiO-1000, SiO-100, FC40, and castor oil as phase 3, P3) across the interface between a pair of coflowing streams (PEG as P1, SiO-100, SiO-20, FC40, and olive oil as P2) having large IFT (∼10 mN/m), with the three different phases immiscible. Interfacial migration involving interfaces of large IFT is facilitated by confining droplets between the channel wall and coflow interface. We find that contact between droplets and the coflow interface is governed by the confinement ratio (i.e., the ratio of drop size to stream width) and the ratio of the capillary numbers of the coflowing streams. Depending on the sign of the spreading parameter (S) of the co-flowing phases, droplet migration or spreading at the interface is observed. While interfacial migration is observed for S1 < 0 and S2 > 0, droplet spreading is observed for S1 < 0 and S2 < 0, where S1 and S2 are P1 and P2 side spreading parameters, respectively. We investigate the droplet migration dynamics and time evolution of the contact line and the interface. Our results show that the speed of interfacial migration increases with increasing spreading parameter contrast between the coflowing phases. In the droplet spreading case, we experimentally study the variation in the spreading length with time, revealing three distinct regimes in good agreement with predictions from analytical scaling. Our study explores the interfacial transport of droplets involving high IFT interfaces, advancing the fundamental understanding of the topic that may find relevance in droplet microfluidics.
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Affiliation(s)
- Shamik Hazra
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036 Tamilnadu, India
| | - Sushanta Mitra
- Waterloo Institute for Nanotechnology, Department of Mechanical & Mechatronics Engineering, University of Waterloo, Waterloo, N2L 3G1 Ontario, Canada
| | - Ashis Kumar Sen
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036 Tamilnadu, India
- Micro Nano Bio-Fluidics Group, Indian Institute of Technology Madras, Chennai, 600036 Tamilnadu, India
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Maktabi S, Malmstadt N, Schertzer JW, Chiarot PR. An integrated microfluidic platform to fabricate single-micrometer asymmetric giant unilamellar vesicles (GUVs) using dielectrophoretic separation of microemulsions. BIOMICROFLUIDICS 2021; 15:024112. [PMID: 33912267 PMCID: PMC8064763 DOI: 10.1063/5.0047265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
We present a microfluidic technique that generates asymmetric giant unilamellar vesicles (GUVs) in the size range of 2-14 μm. In our method, we (i) create water-in-oil emulsions as the precursors to build synthetic vesicles, (ii) deflect the emulsions across two oil streams containing different phospholipids at high throughput to establish an asymmetric architecture in the lipid bilayer membranes, and (iii) direct the water-in-oil emulsions across the oil-water interface of an oscillating oil jet in a co-flowing confined geometry to encapsulate the inner aqueous phase inside a lipid bilayer and complete the fabrication of GUVs. In the first step, we utilize a flow-focusing geometry with precisely controlled pneumatic pressures to form monodisperse water-in-oil emulsions. We observed different regimes in forming water-in-oil multiphase flows by changing the applied pressures and discovered a hysteretic behavior in jet breakup and droplet generation. In the second step of GUV fabrication, an oil stream containing phospholipids carries the emulsions into a separation region where we steer the emulsions across two parallel oil streams using active dielectrophoretic and pinched-flow fractionation separations. We explore the effect of applied DC voltage magnitude and carrier oil stream flow rate on the separation efficiency. We develop an image processing code that measures the degree of mixing between the two oil streams as the water-in-oil emulsions travel across them under dielectrophoretic steering to find the ideal operational conditions. Finally, we utilize an oscillating co-flowing jet to complete the formation of asymmetric giant unilamellar vesicles and transfer them to an aqueous phase. We investigate the effect of flow rates on properties of the co-flowing jet oscillating in the whipping mode (i.e., wavelength and amplitude) and define the phase diagram for the oil-in-water jet. Assays used to probe the lipid bilayer membrane of fabricated GUVs showed that membranes were unilamellar, minimal residual oil remained trapped between the two lipid leaflets, and 83% asymmetry was achieved across the lipid bilayers of GUVs.
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Affiliation(s)
| | - Noah Malmstadt
- Departments of Chemical Engineering & Materials Science, Biomedical Engineering, and Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | | | - Paul R. Chiarot
- Author to whom correspondence should be addressed:. Tel.: +1 607 777 3208
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Jayaprakash KS, Sen AK. Droplet encapsulation of particles in different regimes and sorting of particle-encapsulating-droplets from empty droplets. BIOMICROFLUIDICS 2019; 13:034108. [PMID: 31123540 PMCID: PMC6517185 DOI: 10.1063/1.5096937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 04/29/2019] [Indexed: 05/17/2023]
Abstract
Encapsulation of microparticles in droplets has profound applications in biochemical assays. We investigate encapsulation of rigid particles (polystyrene beads) and deformable particles (biological cells) inside aqueous droplets in various droplet generation regimes, namely, squeezing, dripping, and jetting. Our study reveals that the size of the positive (particle-encapsulating) droplets is larger or smaller compared to that of the negative (empty) droplets in the dripping and jetting regimes but no size contrast is observed in the squeezing regime. The size contrast of the positive and negative droplets in the different regimes is characterized in terms of capillary number C a and stream width ratio ω (i.e., ratio of stream width at the throat to particle diameter ω = w / d p ). While for deformable particles, the positive droplets are always larger compared to the negative droplets, for rigid particles, the positive droplets are larger in the dripping and jetting regimes for 0.50 ≤ ω ≤ 0.80 but smaller in the jetting regime for ω < 0.50 . We exploit the size contrast of positive and negative droplets for sorting across the fluid-fluid interface based on noninertial lift force (at R e ≪ 1 ), which is a strong function of droplet size. We demonstrate sorting of the positive droplets encapsulating polystyrene beads and biological cells from the negative droplets with an efficiency of ∼95% and purity of ∼65%. The proposed study will find relevance in single-cell studies, where positive droplets need to be isolated from the empty droplets prior to downstream processing.
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Affiliation(s)
- K. S. Jayaprakash
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - A. K. Sen
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
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Hazra S, Jayaprakash KS, Pandian K, Raj A, Mitra SK, Sen AK. Non-inertial lift induced migration for label-free sorting of cells in a co-flowing aqueous two-phase system. Analyst 2019; 144:2574-2583. [DOI: 10.1039/c8an02267d] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We present a novel label-free passive microfluidic technique for isolation of cancer cells (EpCAM+ and CD45−) from peripheral blood mononuclear cells (PBMCs) (CD45+ and EpCAM−) in aqueous two-phase system (ATPS).
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Affiliation(s)
- S. Hazra
- Department of Mechanical Engineering
- Indian Institute of Technology Madras
- Chennai-600036
- India
| | - K. S. Jayaprakash
- Department of Mechanical Engineering
- Indian Institute of Technology Madras
- Chennai-600036
- India
| | - K. Pandian
- Department of Mechanical Engineering
- Indian Institute of Technology Madras
- Chennai-600036
- India
| | - A. Raj
- Department of Mechanical Engineering
- Indian Institute of Technology Madras
- Chennai-600036
- India
| | - S. K. Mitra
- Waterloo Institute for Nanotechnology
- University of Waterloo
- Canada
| | - A. K. Sen
- Department of Mechanical Engineering
- Indian Institute of Technology Madras
- Chennai-600036
- India
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Yuan D, Zhao Q, Yan S, Tang SY, Alici G, Zhang J, Li W. Recent progress of particle migration in viscoelastic fluids. LAB ON A CHIP 2018; 18:551-567. [PMID: 29340388 DOI: 10.1039/c7lc01076a] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Recently, research on particle migration in non-Newtonian viscoelastic fluids has gained considerable attention. In a viscoelastic fluid, three dimensional (3D) particle focusing can be easily realized in simple channels without the need for any external force fields or complex microchannel structures compared with that in a Newtonian fluid. Due to its promising properties for particle precise focusing and manipulation, this field has been developed rapidly, and research on the field has been shifted from fundamentals to applications. This review will elaborate the recent progress of particle migration in viscoelastic fluids, especially on the aspect of applications. The hydrodynamic forces on the micro/nano particles in viscoelastic fluids are discussed. Next, we elaborate the basic particle migration in viscoelasticity-dominant fluids and elasto-inertial fluids in straight channels. After that, a comprehensive review on the applications of viscoelasticity-induced particle migration (particle separation, cell deformability measurement and alignment, particle solution exchange, rheometry-on-a-chip and others) is presented; finally, we thrash out some perspectives on the future directions of particle migration in viscoelastic fluids.
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Affiliation(s)
- Dan Yuan
- School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
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Srivastava A, Karthick S, Jayaprakash KS, Sen AK. Droplet Demulsification Using Ultralow Voltage-Based Electrocoalescence. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:1520-1527. [PMID: 29236503 DOI: 10.1021/acs.langmuir.7b03323] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Demulsification of droplets stabilized with surfactant is very challenging due to their low surface energy. We report ultralow voltage-based electrocoalescence phenomenon for the demulsification of aqueous droplets with an aqueous stream. In the absence of electric field, due to the disjoining pressure resulting from the tail-tail interaction between the surfactant molecules present on the aqueous droplets and interface, coalescence of aqueous droplets with the aqueous stream is prevented. However, above a critical electric field, the electrical stress overcomes the disjoining pressure, thus leading to the droplet coalescence. The influence of surfactant concentration, droplet diameter, and velocity on the electrocoalescence phenomena is studied. The macroscopic contact between the aqueous droplet with the aqueous stream enables droplet coalescence at much lower voltage (10 to 90 V), which is at least two orders of magnitude smaller than voltages used in prior works (1.0 to 3.0 kV). The electrocoalescence phenomena is used for the extraction of microparticles encapsulated in aqueous droplets into the aqueous stream and size-based selective demulsification. A new paradigm of droplet electrocoalescence and content extraction is presented that would find significant applications in chemistry and biology.
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Affiliation(s)
- A Srivastava
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
| | - S Karthick
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
| | - K S Jayaprakash
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
| | - A K Sen
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
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Del Giudice F, Sathish S, D’Avino G, Shen AQ. “From the Edge to the Center”: Viscoelastic Migration of Particles and Cells in a Strongly Shear-Thinning Liquid Flowing in a Microchannel. Anal Chem 2017; 89:13146-13159. [DOI: 10.1021/acs.analchem.7b02450] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Francesco Del Giudice
- Micro/Bio/Nanofluidics
Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
- Systems
and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1
8EN, U.K
| | - Shivani Sathish
- Micro/Bio/Nanofluidics
Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Gaetano D’Avino
- Dipartimento
di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Universitá degli Studi di Napoli Federico II, Piazzale Tecchio 80, 80125 Naples, Italy
| | - Amy Q. Shen
- Micro/Bio/Nanofluidics
Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
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