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Hoque SZ, Sen AK. Dynamics of a two-layer immiscible fluid system exposed to ultrasound. J Acoust Soc Am 2024; 155:1655-1666. [PMID: 38426837 DOI: 10.1121/10.0025023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 02/08/2024] [Indexed: 03/02/2024]
Abstract
The relocation dynamics of a two-layer immiscible fluid system exposed to bulk acoustic waves using simulations and experiments are reported. A theoretical formulation of the acoustic radiation pressure (ARP) acting on the interface reveals that ARP is a nonlinear function of the impedance contrast. It has been shown that the force acting on the interface is the simple sum of the ARP and the interfacial tension, which is dependent on the angle of the interface. It was discovered that although the acoustic radiation force is directed from high-impedance fluid (HIF) to low-impedance fluid (LIF), the final steady-state configuration depends on the wall-fluid contact angle (CA). Our study reveals that the HIF and LIF would relocate to the channel center for CA>110°, and CA<70°, respectively, while complete flipping of the fluids is observed for intermediate angles. The forces relocate the fluids in the channel, generally, by a clockwise or anticlockwise rotation. Here, it is demonstrated that the direction of this twist can be determined by the relative densities and wettabilities of the two fluids.
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Affiliation(s)
- S Z Hoque
- Micro Nano Bio Fluidics Unit, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - A K Sen
- Micro Nano Bio Fluidics Unit, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
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2
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Nampoothiri KN, Nath A, Satpathi NS, Sen AK. Deicing of Sessile Droplets Using Surface Acoustic Waves. Langmuir 2023; 39:3934-3941. [PMID: 36883239 DOI: 10.1021/acs.langmuir.2c03208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Deicing has significant relevance in various applications such as transportation, energy production, and telecommunication. The use of surface acoustic waves (SAWs) is an attractive option for deicing as it offers several advantages such as localized heating, in situ control, low power, and system integration for highly efficient deicing. Here, we report an understanding of the dynamics of deicing of microlitre volume water droplets (1 to 30 μL) exposed to low power (0.3 W) SAW actuation using an interdigitated electrode on a piezoelectric (LiNbO3) substrate. We study the time variation of the volume of liquid water from the onset of SAW actuation to complete deicing, which takes 2.5 to 35 s depending on the droplet volume. The deicing phenomenon is attributed to acoustothermal heating which is found to be greatly influenced by the loss of ice adhesion with the substrate and the acoustic streaming within the liquid water. Acoustothermal heating inside the droplet is characterized by the temperature distribution inside the droplet using infrared thermography, and acoustic streaming is observed using dye-based optical microscopy. A rapid enhancement in deicing is observed upon the detachment of ice from the substrate and the onset of acoustic streaming, marked by a sudden increase in the liquid water volume, droplet temperature, and heat transfer coefficient. The deicing time is found to increase linearly with droplet volume as observed from experiments and further verified using a theoretical model. Our study provides an improved understanding of the recently introduced SAW-based deicing technique that may open up the avenue for a suitable alternative to standard deicing protocols.
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Affiliation(s)
- K N Nampoothiri
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, Tamilnadu 600036, India
- Department of Mechanical Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Chennai, Tamilnadu 601103, India
| | - A Nath
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, Tamilnadu 600036, India
| | - N S Satpathi
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, Tamilnadu 600036, India
| | - A K Sen
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, Tamilnadu 600036, India
- Micro Nano Bio-Fluidics Group, Indian Institute of Technology Madras, Chennai, Tamilnadu 600036, India
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3
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Satpathi NS, Nampoothiri KN, Sen AK. Effects of surface acoustic waves on droplet impact dynamics. J Colloid Interface Sci 2023; 641:499-509. [PMID: 36948105 DOI: 10.1016/j.jcis.2023.03.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/02/2023] [Accepted: 03/08/2023] [Indexed: 03/13/2023]
Abstract
HYPOTHESIS Surface acoustic waves (SAW) propagating along a solid surface can significantly affect the dynamics of droplet impact. Although droplet impact in presence of SAW has been attempted recently, here, we investigate the effects of surface wettability, droplet size, impact velocity, and SAW power on the impact and spreading dynamics along with post-impact oscillation dynamics of a drop. EXPERIMENTS Here, we study droplet impact on a surface exposed to traveling SAW produced using an interdigitated electrode patterned on a piezoelectric substrate. The effects of Weber number (We), surface wettability, and SAW power on the impact and spreading dynamics and post-impact oscillation dynamics are studied. FINDINGS Our study unravels that the interplay between capillary and viscous forces, and inertia forces arising due to pre-impact kinetic energy and SAW-induced bulk acoustic streaming underpins the phenomena. Remarkably, we find that the effect of SAW on droplet impact dynamics is predominant in the case of a hydrophilic (HPL) substrate at a higher SAW power and smaller We and hydrophobic (HPB) substrate irrespective of SAW power. Our study reveals that the maximum droplet spreading diameter increases with SAW power at smaller We for an HPL surface whereas it is independent of SAW power at higher We. Post-impact oscillation of a droplet over an HPL surface is found to be overdamped with a smaller amplitude compared to an HPB substrate, and a faster decay in oscillation amplitude is observed in the case of an HPB surface and higher We. Our study provides an improved understanding of droplet impact on a surface exposed to SAW that may find relevance in various practical applications.
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Affiliation(s)
- N S Satpathi
- Micro Nano Bio Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, Tamil Nadu, India
| | - K N Nampoothiri
- Micro Nano Bio Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, Tamil Nadu, India
| | - A K Sen
- Micro Nano Bio Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, Tamil Nadu, India.
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Hoque SZ, Sen AK. Ultrasound resonance in coflowing immiscible liquids in a microchannel. Phys Rev E 2023; 107:035104. [PMID: 37073059 DOI: 10.1103/physreve.107.035104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 02/22/2023] [Indexed: 04/20/2023]
Abstract
We study ultrasonic resonance in a coflow system comprising a pair of immiscible liquids in a microchannel exposed to bulk acoustic waves. We show using an analytical model that there are two resonating frequencies corresponding to each of the coflowing liquids, which depend on the speed of sound and stream width of the liquid. We perform a frequency domain analysis using numerical simulations to reveal that resonance can be achieved by actuating both liquids at a single resonating frequency that depends on the speeds of sound, densities, and widths of the liquids. In a coflow system with equal speeds of sound and densities of the pair of fluids, the resonating frequency is found to be independent of the relative width of the two streams. In coflow systems with unequal speeds of sound or densities, even with matching characteristic acoustic impedances, the resonating frequency depends on the stream width ratio, and the value increases with an increase in the stream width of the liquid with a higher speed of sound. We show that a pressure nodal plane can be realized at the channel center by operating at a half-wave resonating frequency when the speeds of sound and densities are equal. However, the pressure nodal plane is found to shift away from the center of the microchannel when the speeds of sound and densities of the two liquids are unequal. The results of the model and simulations are verified experimentally via acoustic focusing of microparticles suggesting the formation of a pressure nodal plane and hence a resonance condition. Our study will find relevance in acoustomicrofluidics involving immiscible coflow systems.
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Affiliation(s)
- S Z Hoque
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - A K Sen
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
- Micro Nano Bio-Fluidics Group, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
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Nath A, Sudeepthi A, Sen AK. Trapping of Aqueous Droplets under Surface Acoustic Wave-Driven Streaming in Oil-Filled Microwells. Langmuir 2022; 38:4763-4773. [PMID: 35395155 DOI: 10.1021/acs.langmuir.2c00468] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Microwell arrays are ideal platforms for cell culturing, cell separation, and low-volume liquid handling. The ability to manipulate droplets in microwells could open up the opportunity for developing new biochemical assays. Here, we study the trapping of aqueous droplets in an oil-filled microwell driven by the application of nanometer amplitude vibrations called surface acoustic waves (SAW). We elucidate the dynamics of the droplet within the vortex toward the final trapping location and the physics of the trapping phenomenon using a theoretical model by considering the relevant forces. Our study revealed that the combined effect of acoustic radiation and hydrodynamic forces leads to droplet migration and trapping. We demarcate the trapping and nontrapping regimes in terms of the minimum critical input power required for the trapping of droplets of different sizes and densities. We find that the critical power varies as the square of the droplet size and is higher for a denser droplet. The effects of input power and droplet size on the trapping location and trapping time are also studied.
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Malik L, Nath A, Nandy S, Laurell T, Sen AK. Acoustic particle trapping driven by axial primary radiation force in shaped traps. Phys Rev E 2022; 105:035103. [PMID: 35428152 DOI: 10.1103/physreve.105.035103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
We study particle trapping driven by the axial primary radiation force (A-PRF) in shaped traps exposed to standing bulk acoustic waves (S-BAW) using numerical simulations and experiments. The utilization of the stronger A-PRF as the main retention force is a consequence of standing-wave formation along the flow direction, instead of the orthogonal direction as in the case of traditionally used lateral-PRF S-BAW trapping setups. The study of particle dynamics reveals that the competition between A-PRF and viscous drag force governs particle trajectory. The ratio of the acoustic energy to the viscous work (β) provides a general criterion for particle trapping at a distinctive off-node site that is spatially controllable. Particles get trapped for β≥β_{cr} at some distance away from the nodal plane and the distance varies as β^{-c} (c=0.6-1.0). The use of A-PRF as the retention force could potentially allow traditional S-BAW trapping systems to envisage high-throughput advancements surpassing the current standards in cell-handling unit operations.
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Affiliation(s)
- L Malik
- Fluid Systems Lab, Dept. of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
| | - A Nath
- Fluid Systems Lab, Dept. of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
| | - S Nandy
- Fluid Systems Lab, Dept. of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
| | - T Laurell
- Division of Nanobiotechnology, Department of Biomedical Engineering, Lund University, Lund University, 221 84 Lund, Sweden
| | - A K Sen
- Fluid Systems Lab, Dept. of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
- Micro Nano Bio -Fluidics Group, Indian Institute of Technology Madras, Chennai-600036, India
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Shaida MA, Dutta RK, Sen AK, Ram SS, Sudarshan M, Naushad M, Boczkaj G, Nawab MS. Chemical analysis of low carbon content coals and their applications as dye adsorbent. Chemosphere 2022; 287:132286. [PMID: 34600349 DOI: 10.1016/j.chemosphere.2021.132286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/12/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
Coal is primarily a fuel material but lately it has been utilized as an adsorbent for removing toxic metal ions. However, its usage for removing organic pollutants is not well studied. We report here a systematic study on the use of coal samples of varying carbon contents as adsorbents for removing Basic Blue 41 as a model cationic dye. The coal samples were collected from coal mines and were thoroughly characterized. The concentrations of carbon, hydrogen, oxygen, nitrogen and sulphur contents were measured by CHNS analyzer. The concentrations of aluminum, silicon, sulphur, titanium and iron were determined by EDXRF, which corresponded to silicon dioxide (quartz) and aluminium silicate (kaolinite) as the major mineral inclusions, corroborated by XRD results and micrographs showing elemental maps determined from SEM-EDAX. The coal samples with low carbon content revealed higher adsorption capacity (qe ∼ 8.0-9.3 mg/g) of Basic Blue dye at optimized adsorbent dose (2 mg/mL), pH 9 and contact time (120 min). The adsorption kinetic studies satisfied pseudo second order model and the intra-particle diffusion of the dye was evident. The dye adsorption followed Langmuir adsorption isotherm, and the qmax values ranged between 17 and 30 mg/g for low carbon content coal. The FT-IR, Brunauer-Emmett-Teller (BET) surface area and zeta potential results of the coal samples could explain the adsorption phenomenon of cationic dye. The kinetic and thermodynamic studies revealed that the adsorption of Basic Blue 41 dye was based on chemisorptions mechanism.
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Affiliation(s)
- Mohd Azfar Shaida
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
| | - R K Dutta
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - A K Sen
- Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - S S Ram
- UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata, 700098, India
| | - M Sudarshan
- UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata, 700098, India
| | - Mu Naushad
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
| | - Grzegorz Boczkaj
- Department of Process Engineering and Chemical Technology, Faculty of Chemistry, Gdańsk University of Technology, Gdańsk, Poland
| | - Md Sadique Nawab
- Environmental Engineering, Department of Civil Engineering, Indian Institute of Technology, Roorkee, 247667, India
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Gaikwad R, Thangaraj PR, Sen AK. Microfluidics-based rapid measurement of nitrite in human blood plasma. Analyst 2022; 147:3370-3382. [DOI: 10.1039/d2an00020b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report direct and rapid measurement of nitrite in human blood plasma using a fluorescence-based microfluidic method.
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Affiliation(s)
- R. Gaikwad
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
| | - P. R. Thangaraj
- Department of Cardiothoracic Surgery, Apollo Hospital, Chennai, 600006, India
| | - A. K. Sen
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
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Abstract
We report elastocapillary interaction between a long rectangular membrane fixed along its central axis and a liquid drop dispensed at one of its ends. The introduction of the drop results in the elastocapillary-driven wrapping of the membrane along its width and a concomitant flow in the resulting conduit along its length. Depending upon the drop size (d) and capillary length scale (Lc), we identified general criteria for achieving complete wrapping of the membrane in the dry state from energy considerations. For small droplets satisfying d ≲ Lc, we find that the critical membrane length (Wc) required for complete wrapping is proportional to the elastocapillary length scale (Lec). In the case of large droplets with d > Lc, the wrapping behavior depends on the ratio of membrane width to elastocapillary length scale (W/Lec) and the ratio of capillary length scale to the elastocapillary length scale (Lc/Lec). Our study suggests that the critical membrane width for complete wrapping is smaller in the wet state compared to that in the dry state, which can be attributed to the existence of a transmembrane pressure in the wet state. The effect of membrane thickness and width and drop volume on the length and cross-section of the wrapped conduit and attached width of the wrapped membrane is studied. For small droplets, the resulting elastocapillary flow exhibits an inertial regime at small times, followed by a Washburn regime at intermediate times, and finally an inertial regime, and for large droplets, only an inertial regime is observed throughout.
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Affiliation(s)
- R A Samy
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India.
| | - N S Satpathi
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India.
| | - A K Sen
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India.
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Abstract
The development of a biosensor for rapid and quantitative detection of the dengue virus continues to remain a challenge. We report a lab-on-chip device that combines membrane-based blood plasma separation and a localized surface plasmon resonance (LSPR) based biosensor for on-chip detection of dengue NS1 antigen from a few drops of blood. The LSPR effect is realized by irradiating UV-NIR light having a spectral peak at 655 nm onto nanostructures fabricated via thermal annealing of a thin metal film. We study the effect of the resulting metal nanostructures on the LSPR performance in terms of sensitivity and limit of detection, by annealing silver films at temperatures ranging from 100 to 500 °C. The effect of annealing temperature on the nanostructure size and uniformity and the resulting optical characteristics are investigated. Further, the binding between non-targeted blood plasma proteins and NS1-antibody-functionalized nanostructures on the LSPR performance is studied by considering different blocking mechanisms. Using a nanostructure annealed at 200 °C and 2X-phosphate buffer saline with 0.05% Tween-20 as the blocking buffer, from 10 μL of whole blood, the device can detect NS1 antigen at a concentration as low as 0.047 μg mL-1 within 30 min. Finally, we demonstrate the detection of NS1 in the blood samples of dengue-infected patients and validate our results with those obtained from the gold-standard ELISA test.
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Affiliation(s)
- S Lathika
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras Chennai India
| | - A Raj
- Department of Mechanical Engineering, Indian Institute of Technology Patna Patna India
| | - A K Sen
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras Chennai India
- Micro Nano Bio Fluidics Group, Indian Institute of Technology Madras Chennai India
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11
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Hemachandran E, Hoque SZ, Laurell T, Sen AK. Reversible Stream Drop Transition in a Microfluidic Coflow System via On Demand Exposure to Acoustic Standing Waves. Phys Rev Lett 2021; 127:134501. [PMID: 34623851 DOI: 10.1103/physrevlett.127.134501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 07/16/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Transition between stream and droplet regimes in a coflow is typically achieved by adjusting the capillary numbers (Ca) of the phases. Remarkably, we experimentally evidence a reversible transition between the two regimes by controlling exposure of the system to acoustic standing waves, with Ca fixed. By satisfying the ratio of acoustic radiation force to the interfacial tension force, Ca_{ac}>1, experiments reveal a reversible stream drop transition for Ca<1, and stream relocation for Ca≥1. We explain the phenomenon in terms of the pinching, advection, and relocation timescales and a transition between convective and absolute instability from a linear stability analysis [P. Guillot et al., Phys. Rev. Lett. 99, 104502 (2007)PRLTAO0031-900710.1103/PhysRevLett.99.104502].
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Affiliation(s)
- E Hemachandran
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, 600036 Chennai, India
| | - S Z Hoque
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, 600036 Chennai, India
| | - T Laurell
- Division of Nanobiotechnology, Department of Biomedical Engineering, Lund University, 22363 Lund, Sweden
| | - A K Sen
- Fluid Systems Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, 600036 Chennai, India
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12
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Hoque SZ, Nath A, Sen AK. Dynamical motion of a pair of microparticles at the acoustic pressure nodal plane under the combined effect of axial primary radiation and interparticle forces. J Acoust Soc Am 2021; 150:307. [PMID: 34340505 DOI: 10.1121/10.0005521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
The dynamical motion of a pair of microparticles exposed to acoustic standing waves and located at the pressure nodal plane is studied using numerical simulations and experiments. The insight into their dynamical behavior along the pressure nodal plane due to the competition between the axial primary radiation and interparticle forces is elucidated. An expression for axial primary radiation force acting on a particle is derived, and the particle dynamics is simulated using fluid-structure interaction model based on the arbitrary Lagrangian-Eulerian method. Considering the total radiation force acting on a particle is the sum of the axial primary radiation force and the interparticle force, three distinct dynamical regimes are observed depending upon the relative magnitudes of the acoustic forces which in turn depend on the gradient of the acoustic energy density. Acceleration, deceleration, and constant velocity motion of the pair of approaching particles are observed, which are explained by the interplay of the acoustic and non-acoustic forces. The dynamical motion of the pair of particles predicted using the model is in very good agreement with the experimental observations.
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Affiliation(s)
- S Z Hoque
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - A Nath
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - A K Sen
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
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Banerjee U, Jain SK, Sen AK. Particle encapsulation in aqueous ferrofluid drops and sorting of particle-encapsulating drops from empty drops using a magnetic field. Soft Matter 2021; 17:6020-6028. [PMID: 34060567 DOI: 10.1039/d1sm00530h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Handling and manipulation of particle-encapsulating droplets (PED) have profound applications in biochemical assays. Herein we report encapsulation of microparticles in aqueous ferrofluid droplets in a primary continuous phase (CP) and sorting of PED from empty droplets (ED) at the interface of the CP in coflow with a second continuous phase using a magnetic field. We find that the encapsulation process results in a size contrast between the PED and ED that depends on the flow regime - squeezing, dripping, or jetting - which in turn is governed by the ratio of the discrete phase to the continuous phase capillary number, Car. The difference between the volume fractions of ferrofluid in the PED and ED, ΔαPED, is utilized for sorting, and is found to depend on the ratio of the capillary numbers, Car. The difference ΔαPED is found to be maximum in the jetting regime, suggesting that the jetting regime is most suitable for encapsulation and sorting. The sorting criterion is represented in terms of a parameter ξ, which is a function of the ratios of the magnetic force to the interfacial force experienced by the PED and ED. Our study revealed that sorting is possible for ξ < 0, which corresponds to ΔαPED > 0.25. The maximum sorting efficiency of our system is found to be ∼95% at a throughput of ∼100 drops per s.
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Affiliation(s)
- U Banerjee
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
| | - S K Jain
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
| | - A K Sen
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
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Majhy B, Priyadarshini P, Sen AK. Effect of surface energy and roughness on cell adhesion and growth - facile surface modification for enhanced cell culture. RSC Adv 2021; 11:15467-15476. [PMID: 35424027 PMCID: PMC8698786 DOI: 10.1039/d1ra02402g] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 04/21/2021] [Indexed: 01/17/2023] Open
Abstract
In vitro, cellular processing on polymeric surfaces is fundamental to the development of biosensors, scaffolds for tissue engineering and transplantation. However, the effect of surface energy and roughness on the cell-surface interaction remains inconclusive, indicating a lack of complete understanding of the phenomenon. Here, we study the effect of surface energy (E s) and roughness ratio (r) of a polydimethylsiloxane (PDMS) substrate on cell attachment, growth, and proliferation. We considered two different cell lines, HeLa and MDA MB 231, and rough PDMS surfaces of different surface energy in the range E s = 21-100 mJ m-2, corresponding to WCA 161°-1°, and roughness ratio in the range r = 1.05-3, corresponding to roughness 5-150 nm. We find that the cell attachment process proceeds through three different stages marked by an increase in the number of attached cells with time (stage I), flattening of cells (stage II), and elongation of cells (III) on the surface. Our study reveals that moderate surface energy (E s ≈ 70 mJ m-2) and intermediate roughness ratio (r ≈ 2) constitute the most favourable conditions for efficient cell adhesion, growth, and proliferation. A theoretical model based on the minimization of the total free energy of the cell-substrate system is presented and is used to predict the spread length of cells that compares well with the corresponding experimental data within 10%. The performance and reusability of the rough PDMS surface of moderate energy and roughness prepared via facile surface modification are compared with standard T-25 cell culture plates for cell growth and proliferation, which shows that the proposed surface is an attractive choice for efficient cell culture.
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Affiliation(s)
- B Majhy
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras Chennai India
| | - P Priyadarshini
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras Chennai India
| | - A K Sen
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras Chennai India
- Micro Nano Bio Fluidics Group, Indian Institute of Technology Madras Chennai India
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Gaikwad R, Thangaraj PR, Sen AK. Direct and rapid measurement of hydrogen peroxide in human blood using a microfluidic device. Sci Rep 2021; 11:2960. [PMID: 33536535 PMCID: PMC7858642 DOI: 10.1038/s41598-021-82623-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/22/2021] [Indexed: 02/07/2023] Open
Abstract
The levels of hydrogen peroxide (\documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2) in human blood is of great relevance as it has emerged as an important signalling molecule in a variety of disease states. Fast and reliable measurement of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 levels in the blood, however, continues to remain a challenge. Herein we report an automated method employing a microfluidic device for direct and rapid measurement of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in human blood based on laser-induced fluorescence measurement. Our study delineates the critical factors that affect measurement accuracy—we found blood cells and soluble proteins significantly alter the native \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 levels in the time interval between sample withdrawal and detection. We show that separation of blood cells and subsequent dilution of the plasma with a buffer at a ratio of 1:6 inhibits the above effect, leading to reliable measurements. We demonstrate rapid measurement of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in plasma in the concentration range of 0–49 µM, offering a limit of detection of 0.05 µM, a sensitivity of 0.60 µM−1, and detection time of 15 min; the device is amenable to the real-time measurement of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in the patient’s blood. Using the linear correlation obtained with known quantities of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2, the endogenous \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 concentration in the blood of healthy individuals is found to be in the range of 0.8–6 µM. The availability of this device at the point of care will have relevance in understanding the role of \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in health and disease.
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Affiliation(s)
- R Gaikwad
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India
| | - P R Thangaraj
- Department of Cardiothoracic Surgery, Apollo Hospital, Chennai, 600006, India
| | - A K Sen
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
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16
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Abstract
Microwell arrays are amongst the most commonly used platforms for biochemical assays. However, the coalescence of droplets that constitute the dispersed phase of suspensions housed within microwells has not received much attention to date. Herein, we study the coalescence of droplets in a two-phase system in a microwell driven by surface acoustic waves (SAWs). The microwell structure, together with symmetric exposure to SAW irradiation, coupled from beneath the microwell via a piezoelectric substrate, gives rise to the formation of a pair of counter-rotating vortices that enable droplet transport, trapping, and coalescence. We elucidate the physics of the coalescence phenomenon using a scaling analysis of the relevant forces, namely, the acoustic streaming-induced drag force, the capillary and viscous forces associated with the drainage of the thin continuous phase film between the droplets and the van der Waals attraction force. We confirm that droplet-droplet interface contact is established through the formation of a liquid bridge, whose neck radius grows linearly in time in the preceding viscous regime and proportionally with the square root of time in the subsequent inertial regime. Further, we investigate the influence of the input SAW power and droplet size on the film drainage time and demarcate the coalescence and non-coalescence regimes to derive a criterion for the onset of coalescence. The distinct deformation patterns observed for a pair of contacting droplets in both the regimes are elucidated and the possibility for driving concurrent coalescence of multiple droplets is demonstrated. We expect the study will find relevance in the demulsification of immiscible phases and the mixing of samples/reagents within microwells for a variety of biochemical applications.
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Affiliation(s)
- A Sudeepthi
- Micro Nano Bio -Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - A Nath
- Micro Nano Bio -Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - L Y Yeo
- Micro/Nanophysics Research Laboratory, School of Engineering, Royal Melbourne Institute of Technology (RMIT University), Melbourne, Victoria 3001, Australia
| | - A K Sen
- Micro Nano Bio -Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
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17
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Abstract
Single-cell analysis has emerged as a powerful method for genomics, transcriptomics, proteomics, and metabolomics characterisation at the individual cell level. Here, we demonstrate a technique for the detection and selective isolation of target cells encapsulated in microdroplets in single-cell format. A sample containing a mixed population of cells with fluorescently labelled target cells can be focused using a sheath fluid to direct cells in single file toward a droplet junction, wherein the cells are encapsulated inside droplets. The droplets containing the cells migrate toward the centre of the channel owing to non-inertial lift force. The cells present in the droplets are studied and characterised based on forward scatter (FSC), side scatter (SSC), and fluorescence (FL) signals. The FL signals from the target cells can be used to activate a selective isolation module based on electro-coalescence, using suitable electronics and a program to sort droplets containing the target cells in single-cell format from droplets containing background cells. We demonstrated the detection and isolation of target cells (cancer cells: HeLa and DU145) from mixed populations of cells, peripheral blood mononuclear cells (PBMC) + cervical cancer cells (HeLa) and PBMC + human prostate cancer cells (DU145), at a concentration range of 104-106 ml-1 at 300 cells per s. The performance of the device is characterised in terms of sorting efficiency (>97%), enrichment (>1800×), purity (>98%), and recovery (>95%). The sorted target cells were found to be viable (>95% viability) and showed good proliferation when cultured, showing the potential of the proposed sorting technique for downstream analysis.
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Affiliation(s)
- R Gaikwad
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
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18
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Abstract
We show that adjacent liquid droplets exhibit long-range attraction and repulsion on an immiscible liquid impregnating a surface when either the drop or the impregnating liquid is volatile. Remarkably, we find that at small times the interaction is attractive, analogous to the "Cheerios effect", but at large times the interaction becomes repulsive depicting the "reverse-Cheerios effect". Our study reveals that the interaction is underpinned by wetting and capillarity, buoyancy, and evaporation phenomena. We experimentally observe the interaction between a pair of droplets and provide a theoretical framework to quantitatively predict their transport behavior.
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Affiliation(s)
- B Majhy
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamilnadu, India
| | - S K Jain
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamilnadu, India
| | - A K Sen
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamilnadu, India
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19
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Pandian K, Ajanth Praveen M, Hoque SZ, Sudeepthi A, Sen AK. Continuous electrical lysis of cancer cells in a microfluidic device with passivated interdigitated electrodes. Biomicrofluidics 2020; 14:064101. [PMID: 33163136 PMCID: PMC7609135 DOI: 10.1063/5.0026046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/17/2020] [Indexed: 06/11/2023]
Abstract
Cell lysis is a critical step in genomics for the extraction of cellular components of downstream assays. Electrical lysis (EL) offers key advantages in terms of speed and non-interference. Here, we report a simple, chemical-free, and automated technique based on a microfluidic device with passivated interdigitated electrodes with DC fields for continuous EL of cancer cells. We show that the critical problems in EL, bubble formation and electrode erosion that occur at high electric fields, can be circumvented by passivating the electrodes with a thin layer (∼18 μm) of polydimethylsiloxane. We present a numerical model for the prediction of the transmembrane potential (TMP) at different coating thicknesses and voltages to verify the critical TMP criterion for EL. Our simulations showed that the passivation layer results in a uniform electric field in the electrode region and offers a TMP in the range of 5-7 V at an applied voltage of 800 V, which is well above the critical TMP (∼1 V) required for EL. Experiments revealed that lysis efficiency increases with an increase in the electric field (E) and residence time (tr): a minimum E ∼ 105 V/m and tr ∼ 1.0 s are required for efficient lysis. EL of cancer cells is demonstrated and characterized using immunochemical staining and compared with chemical lysis. The lysis efficiency is found to be ∼98% at E = 4 × 105 V/m and tr = 0.72 s. The efficient recovery of genomic DNA via EL is demonstrated using agarose gel electrophoresis, proving the suitability of our method for integration with downstream on-chip assays.
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Affiliation(s)
| | | | | | | | - A. K. Sen
- Author to whom correspondence should be addressed:
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20
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Abstract
The manipulation of aqueous droplets has a profound significance in biochemical assays. Magnetic field-driven droplet manipulation, offering unique advantages, is consequently gaining attention. However, the phenomenon relating to diamagnetic droplets is not well understood. Here, we report the understanding of trapping and coalescence of flowing diamagnetic aqueous droplets in a paramagnetic (oil-based ferrofluid) medium using negative magnetophoresis. Our study revealed that the trapping phenomenon is underpinned by the interplay of magnetic energy (Em) and frictional (viscous) energy (Ef), in terms of magnetophoretic stability number, Sm = (Em/Ef). The trapping and nontrapping regimes are characterized based on the peak value of magnetophoretic stability number, Smp, and droplet size, D*. The study of coalescence of a trapped droplet with a follower droplet (and a train of droplets) revealed that the film-drainage Reynolds number (Refd) representing the coalescence time depends on the magnetic Bond number, Bom. The coalesced droplet continues to remain trapped or gets self-released obeying the Smp and D* criterion. Our study offers an understanding of the magnetic manipulation of diamagnetic aqueous droplets that can potentially be used for biochemical assays in microfluidics.
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Affiliation(s)
- S K Jain
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - U Banerjee
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - A K Sen
- Micro Nano Bio-Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
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21
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Mandal C, Banerjee U, Sen AK. Transport of a Sessile Aqueous Droplet over Spikes of Oil Based Ferrofluid in the Presence of a Magnetic Field. Langmuir 2019; 35:8238-8245. [PMID: 31141667 DOI: 10.1021/acs.langmuir.9b00631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Droplets can be used as carrier vehicles for the transportation of biological and chemical reagents. Manipulation of water- and oil-based ferromagnetic droplets in the presence of a magnetic field has been well-studied. Here, we elucidate the transport of a sessile aqueous (diamagnetic) droplet placed over spikes of oil-based ferrofluid (FF) in the presence of a nonuniform magnetic field. An oil-based FF droplet, dispensed over a rigid oleophilic surface, interacts with a magnetic field to get transformed into an array of spikes which then act as a carrier for the transportation of the aqueous droplet. Our study reveals that transportation phenomena is governed by the interplay of three different forces: magnetic force Fm, frictional force Ff, and interfacial tension force Fi, which is expressed in terms of the magnetic Laplace number ( Lam) and magnetic Bond number ( Bom) as Lam?1 = ( Ff1/ Fm, x) and Bom Lam?1 = ( Ff2/ Fi). Based on the values of the dimensionless numbers, three different regimes, steady droplet transport, spike extraction, and magnet disengagement, are identified. It is found that steady droplet transport is observed for Lam?1 ? 1 and Bom Lam?1 ? 1, whereas extraction of spikes is observed for Lam?1 ? 1 and Bom Lam?1 > 1 and magnet disengagement is observed for Lam?1 > 1. In the steady droplet transport regime, velocity of the aqueous droplet Uds was found to be dependent on the volumes of the aqueous droplet Vw and FF droplet VFF following Uds ? Vw?0.19 VFF0.36. A simple model is presented that accurately predicts the aqueous droplet velocity Uds within 5% of the corresponding experimental data. In the spike extraction regime, the spike extraction distance Lse was found to vary with Vw, VFF, and the magnet velocity Ums following Lse ? Vw?1.75 VFF0.75 Ums?1.56.
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Affiliation(s)
- C Mandal
- Department of Mechanical Engineering , Indian Institute of Technology Madras , Chennai - 600036 , India
| | - U Banerjee
- 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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22
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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23
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Hemachandran E, Karthick S, Laurell T, Sen AK. Relocation of coflowing immiscible liquids under acoustic field in a microchannel. ACTA ACUST UNITED AC 2019. [DOI: 10.1209/0295-5075/125/54002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Karunya R, Jayaprakash KS, Gaikwad R, Sajeesh P, Ramshad K, Muraleedharan KM, Dixit M, Thangaraj PR, Sen AK. Rapid measurement of hydrogen sulphide in human blood plasma using a microfluidic method. Sci Rep 2019; 9:3258. [PMID: 30824728 PMCID: PMC6397262 DOI: 10.1038/s41598-019-39389-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/23/2019] [Indexed: 11/27/2022] Open
Abstract
Hydrogen sulfide (H2S) is emerging as an important gasotransmitter in both physiological and pathological states. Rapid measurement of H2S remains a challenge. We report a microfluidic method for rapid measurement of sulphide in blood plasma using Dansyl-Azide, a fluorescence (FL) based probe. We have measured known quantities of externally added (exogenous) H2S to both buffer and human blood plasma. Surprisingly, a decrease in FL intensity with increase in exogenous sulphide concentration in plasma was observed which is attributed to the interaction between the proteins and sulphide present in plasma underpinning our observation. The effects of mixing and incubation time, pH, and dilution of plasma on the FL intensity is studied which revealed that the FL assay required a mixing time of 2 min, incubation time of 5 min, a pH of 7.1 and performing the test within 10 min of sampling; these together constitute the optimal parameters at room temperature. A linear correlation (with R2 ≥ 0.95) and an excellent match was obtained when a comparison was done between the proposed microfluidic and conventional spectrofluorometric methods for known concentrations of H2S (range 0–100 µM). We have measured the baseline level of endogenous H2S in healthy volunteers which was found to lie in the range of 70 μM – 125 μM. The proposed microfluidic device with DNS-Az probe enables rapid and accurate estimation of a key gasotransmitter H2S in plasma in conditions closely mimicking real time clinical setting. The availability of this device as at the point of care, will help in understanding the role of H2S in health and disease.
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Affiliation(s)
- R Karunya
- 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
| | - R Gaikwad
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India
| | - P Sajeesh
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India
| | - K Ramshad
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India
| | - K M Muraleedharan
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India
| | - M Dixit
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, 600036, India
| | - P R Thangaraj
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.,Department of Cardiothoracic Surgery, Apollo Hospital, Chennai, 600006, India
| | - A K Sen
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
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25
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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26
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Iqbal R, Majhy B, Shen AQ, Sen AK. Evaporation and morphological patterns of bi-dispersed colloidal droplets on hydrophilic and hydrophobic surfaces. Soft Matter 2018; 14:9901-9909. [PMID: 30474686 DOI: 10.1039/c8sm01915k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Understanding the formation of different morphological patterns depending on the particle size and surface wettability has great relevance in the separation, mixing and concentration of micro/nano particles and biological entities. We report the evaporation and morphological patterns of evaporating bi-dispersed colloidal droplets on hydrophilic and hydrophobic surfaces. To explain the underlying mechanisms of various particle distribution patterns, we propose a phenomenological model that accounts for the drag force, van der Waals and electrostatic interaction forces, and surface tension force acting on the particles. In the case of the hydrophilic surface (θ ∼ 27°), there is a competition between the frictional force arising due to the van der Waals (∼10-8 N) and electrostatic interaction forces (∼10-10 N) and the surface tension force (∼10-7 N) that depends on the particle size. Consequently, the smaller particles (0.2 and 1.0 μm in diameter) are found to be pinned and form an outer ring at the contact line whereas the larger particles (3.0 and 6.0 μm in diameter) move inward, either forming an inner ring or flocculating depending on the particle size. Interestingly, a completely different morphological pattern of the micro/nano particles is observed on a hydrophobic substrate (θ ∼ 110°): contact line pinning is no longer observed and particles form a centralized deposition pattern. The order of the magnitude of the surface tension force is higher as compared to the frictional force (∼10-8 N); thus the particles are driven radially inward and accumulate at the center of the droplet. Owing to the mixed mode of evaporation toward the end of evaporation, only a fraction of smaller particles travel radially outward due to the coffee-ring effect. Scanning electron microscopy images reveal that smaller particles are present mostly at the center with a small fraction of smaller particles at the edge of the pattern, whereas larger particles are uniformly distributed throughout.
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Affiliation(s)
- R Iqbal
- Microfluidics Laboratory, Department of Mechanical Engineering, IIT Madras, Chennai, 600036, India.
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27
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Karthick S, Pradeep PN, Kanchana P, Sen AK. Acoustic impedance-based size-independent isolation of circulating tumour cells from blood using acoustophoresis. Lab Chip 2018; 18:3802-3813. [PMID: 30402651 DOI: 10.1039/c8lc00921j] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Label-free isolation of CTCs from blood is critical for the development of diagnostic and prognostic tools for cancer. Here, we report a label-free method based on acoustic impedance contrast for the isolation of CTCs from peripheral blood mononuclear cells (PBMCs) in a microchannel using acoustophoresis. We describe a method in which the acoustophoretic migration of PBMCs is arrested by matching their acoustic impedance with that of the sample medium, and CTCs that have different acoustic impedance compared to PBMCs migrate toward the pressure node or antinode and thus become isolated. We show that acoustic streaming which can adversely affect the CTC isolation is suppressed owing to the inhomogeneous liquid flow configuration. We establish a method for isolation of CTCs that have higher or lower acoustic impedance compared to PBMCs by controlling the acoustic impedance contrast of the liquids across the channel. Applying this method, we demonstrate label-free isolation of HeLa and MDA-MB-231 cells from PBMCs (collected from 2.0 mL of blood) within one hour yielding a recovery of >86% and >50-fold enrichment. Combined impedance and size-based sorting is proposed as a promising tool for the effective isolation of CTCs from blood.
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Affiliation(s)
- S Karthick
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
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28
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Dhiman S, Jayaprakash KS, Iqbal R, Sen AK. Self-Transport and Manipulation of Aqueous Droplets on Oil-Submerged Diverging Groove. Langmuir 2018; 34:12359-12368. [PMID: 30226788 DOI: 10.1021/acs.langmuir.8b01889] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report experimental study of self-transport of aqueous droplets along an oil-submerged diverging groove structure. The migration phenomenon is illustrated, and the effect of various parameters such as droplet size d, oil layer thickness h, groove angle 2θ, and groove thickness δ on the droplet transport behavior (i.e., migration velocity and length) is investigated. Our study reveals that complete engulfment of aqueous droplets in the oil layer, that is attributed to a positive spreading parameter ( S > 0), is a prerequisite for the droplet transport. The results show that only droplets of diameter larger than the oil layer thickness (i.e., d ≥ h) get transported owing to a differential Laplace pressure between the leading and trailing faces of a droplet because of the diverging groove. Using experimental data, the variation of droplet migration velocity with distance along the diverging groove is correlated as U( x) = ψ x-0.9, where ψ = d0.32θ-2.2 h-1.5δ0.7. The submerged groove structure was used to demonstrate simultaneous and sequential coalescence and transport of multiple droplets. Finally, the submerged groove structure was employed for extraction of aqueous droplets from oil. The proposed technique opens up a new avenue for evaporation and contamination free transport and coalescence of droplets for chemical and biological applications.
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Affiliation(s)
- S Dhiman
- 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
| | - R Iqbal
- 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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29
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Raj A, Sen AK. Entry and passage behavior of biological cells in a constricted compliant microchannel. RSC Adv 2018; 8:20884-20893. [PMID: 35542327 PMCID: PMC9080859 DOI: 10.1039/c8ra02763c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/28/2018] [Indexed: 11/30/2022] Open
Abstract
We report an experimental and theoretical investigation of the entry and passage behaviour of biological cells (HeLa and MDA-MB-231) in a constricted compliant microchannel. Entry of a cell into a micro-constriction takes place in three successive regimes: protrusion and contact (cell protrudes its leading edge and makes a contact with the channel wall), squeeze (cell deforms to enter into the constriction) and release (cell starts moving forward). While the protrusion and contact regime is insensitive to the flexibility of the channel, the squeeze zone is significantly smaller in the case of a more compliant channel. Similarly, in the release zone, the acceleration of the cells into the microconstriction is higher in the case of a more compliant channel. The results showed that for a fixed size ratio ρ and E c, the extension ratio λ decreases and transit velocity U c increases with increase in the compliance parameter f p. The variation in the cell velocity is governed by force due to the cell stiffness F s as well as that due to the viscous dampening F d, explained using the Kelvin-Voigt viscoelastic model. The entry time t e = m(ρ) k 1 (1 + f p) k 2 (E c) k 3 and induced hydrodynamic resistance of a cell ΔR c/R = k(ρ) a (1 + k f f p) b (k E E c) c were correlated with cell size ratio ρ, Young's modulus E c and compliance parameter f p, which showed that both entry time t e and the induced hydrodynamic resistance ΔR c are most sensitive to the change in the compliance parameter f p. This study provides understanding of the passage of cells in compliant micro-confinements that can have significant impact on mechanophenotyping of single cells.
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Affiliation(s)
- A Raj
- 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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Banerjee U, Sen AK. Shape evolution and splitting of ferrofluid droplets on a hydrophobic surface in the presence of a magnetic field. Soft Matter 2018; 14:2915-2922. [PMID: 29610807 DOI: 10.1039/c7sm02312j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We elucidate the phenomena of dynamic wetting, shape evolution and splitting of ferrofluid (FF) droplets on a hydrophobic surface under the influence of a magnetic field. In the case of a FF droplet interacting with a magnetic field, both surface energy and magnetic energy contribute to the total Gibb's free energy and hence the wetting phenomena. The nanoparticles in the FF droplet migrate and get accumulated at the apex of the droplet which enhances the magnetic interaction causing large deformation of the droplet. The FF droplet deformation and subsequent splitting are governed by the interplay between the magnetic Fm and surface tension Fs forces. The ratio of the forces km = (Fm/Fs) was found to be a function of the magnetic Bond number Bom and non-dimensional gap g* as km ∼ (Bom)0.3(g*)-0.86. Splitting of the FF droplets was observed for km > 1 and for km < 1, an equilibrium droplet shape was observed. The wetting behavior of the FF droplets was found to be strongly dependent on the FF concentration c - concentrated (c = 1.2%) FF droplets exhibit contact line (CL) pinning and decrease in contact angle (CA) θ with time throughout, while diluted (c = 0.6%) FF droplets show a mixed mode (CL pinning followed by constant CA). In splitting of FF droplets, the ratio of the volume of the daughter droplet to that of the parent droplet i.e. (Vd/Vp), was found to decrease with an increase in the parent droplet size Vp.
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Affiliation(s)
- U Banerjee
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
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Jayaprakash KS, Sen AK. Continuous splitting of aqueous droplets at the interface of co-flowing immiscible oil streams in a microchannel. Soft Matter 2018; 14:725-733. [PMID: 29349475 DOI: 10.1039/c7sm02068f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the continuous splitting of aqueous droplets at the interface between two co-flowing immiscible oil streams in a microchannel. The aqueous droplets initially present in a primary continuous stream (CP1) migrate into a secondary continuous stream (CP2) when the ratio of the non-inertial lift force to the interfacial tension force exceeds a critical value (K. S. Jayaprakash, U. Banerjee and A. K. Sen, Langmuir, 2016, 32, 2136-2143). Here, experiments were performed to understand the droplet splitting phenomenon and demonstrate the splitting of droplets encapsulating microbeads and cells. The results showed that the droplet splitting phenomenon is governed by the capillary number Ca, which is a function of the average shear stress across the channel, interfacial tension σ between the CP1 and the droplet phase and the droplet length-scale L. Irrespective of the individual values of these parameters, droplet splitting was observed when the capillary number Ca exceeds a critical value Cacr, which was found to be a function of droplet to CP2 viscosity ratio λ. The Cacr was found to be minimum for λ ≈ 1 but higher for droplets of λ ≫ 1 and λ ≪ 1. The sizes of the primary and secondary daughter and migrated droplets (i.e. Lp|sD and Lp|sM) were found to increase linearly with the increase in the size of the primary or secondary parent droplets (Lp|sP). Splitting of parent droplets encapsulating a single microbead or PBMC showed that after splitting, the presence of the microbead or PBMC in the daughter or migrated droplets depends on the ratio of the size of the migrated droplets to that of the parent droplet (i.e. VM/VP). Finally, splitting of parent droplets containing two or more microbeads or cells into droplets containing a single particle or cell was demonstrated. A new paradigm of droplet splitting is reported that could find applications in soft matter and single-cell studies.
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Affiliation(s)
- K S Jayaprakash
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
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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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Abstract
We provide improved understanding of acoustophoretic focusing of a dense suspension (volume fraction φ>10%) in a microchannel subjected to an acoustic standing wave using a proposed theoretical model and experiments. The model is based on the theory of interacting continua and utilizes a momentum transport equation for the mixture, continuity equation, and transport equation for the solid phase. The model demonstrates the interplay between acoustic radiation and shear-induced diffusion (SID) forces that is critical in the focusing of dense suspensions. The shear-induced particle migration model of Leighton and Acrivos, coupled with the acoustic radiation force, is employed to simulate the continuum behavior of particles. In the literature, various closures for the diffusion coefficient D_{φ}^{*} are available for rigid spheres at high concentrations and nonspherical deformable particles [e.g., red blood cells (RBCs)] at low concentrations. Here we propose a closure for D_{φ}^{*} for dense suspension of RBCs and validate the proposed model with experimental data. While the available closures for D_{φ}^{*} fail to predict the acoustic focusing of a dense suspension of nonspherical deformable particles like RBCs, the predictions of the proposed model match experimental data within 15%. Both the model and experiments reveal a competition between acoustic radiation and SID forces that gives rise to an equilibrium width w^{*} of a focused stream of particles at some distance L_{eq}^{*} along the flow direction. Using different shear rates, acoustic energy densities, and particle concentrations, we show that the equilibrium width is governed by Péclet number Pe and Strouhal number Stasw^{*}=1.4(PeSt)^{-0.5} while the length required to obtain the equilibrium-focused width depends on St as L_{eq}^{*}=3.8/(St)^{0.6}. The proposed model and correlations would find significance in the design of microchannels for acoustic focusing of dense suspensions such as undiluted blood.
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Affiliation(s)
- S Karthick
- 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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Raj A, Dixit M, Doble M, Sen AK. A combined experimental and theoretical approach towards mechanophenotyping of biological cells using a constricted microchannel. Lab Chip 2017; 17:3704-3716. [PMID: 28983550 DOI: 10.1039/c7lc00599g] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We report a combined experimental and theoretical technique that enables the characterization of various mechanical properties of biological cells. The cells were infused into a microfluidic device that comprises multiple parallel micro-constrictions to eliminate device clogging and facilitate characterization of cells of different sizes and types on a single device. The extension ratio λ and transit velocity Uc of the cells were measured using high-speed and high-resolution imaging which were then used in a theoretical model to predict the Young's modulus Ec = f(λ, Uc) of the cells. The predicted Young's modulus Ec values for three different cell lines (182 ± 34.74 Pa for MDA MB 231, 360 ± 75 Pa for MCF 10A and, 763 ± 93 Pa for HeLa) compare well with those reported in the literature from micropipette measurements and atomic force microscopy measurement within 10% and 15%, respectively. Also, the Young's modulus of MDA-MB-231 cells treated with 50 μM 4-hyrdroxyacetophenone (for localization of myosin II) for 30 min was found out to be 260 ± 52 Pa. The entry time te of cells into the micro-constrictions was predicted using the model and validated using experimentally measured data. The entry and transit behaviors of cells in the micro-constriction including cell deformation (extension ratio λ) and velocity Uc were experimentally measured and used to predict various cell properties such as the Young's modulus, cytoplasmic viscosity and induced hydrodynamic resistance of different types of cells. The proposed combined experimental and theoretical approach leads to a new paradigm for mechanophenotyping of biological cells.
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Affiliation(s)
- A Raj
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
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Samy RA, George D, Sen AK. Bio-inspired liquid transport via elastocapillary interaction of a thin membrane with a liquid meniscus. Soft Matter 2017; 13:6858-6869. [PMID: 28828452 DOI: 10.1039/c7sm00940b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report bio-inspired (from a hummingbird's tongue) liquid transport via elastocapillary interaction of a thin membrane with a liquid meniscus. A soft wedge-thin rectangular membrane forming a wedge with a rigid substrate and a flat thin rectangular membrane undergo large deformation while interacting with liquid menisci. The membrane deformation leads to the formation of confinement which in turn results in elastocapillary flow along the membrane length. A simple theoretical model based on the Euler Bernoulli law is used to predict the membrane deformation profiles, which compare well with that obtained from experiments. In the wedge case, the membrane surface and liquid are selected such that the Concus-Finn criterion is not satisfied to contrast the present case of elastocapillary flow from the typical corner flow reported in the literature. The meniscus location versus time studies indicated that the flow exhibits the typical Washburn regime with , except for a sudden increase in velocity at the end of the membrane length. The effects of membrane thickness and width, liquids and substrates were studied to determine the expression for the modified Washburn constant Wm in both the wedge and flat membranes. It was found that gravity plays a role for Bo > 0.94 and for Bo = 1.9, the effect of inclination angle on the flow was studied. The elastocapillary flow with thin membranes could open up an opportunity for a new area, namely "membrane microfluidics" or "lab on a membrane", for diagnostics and other applications.
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Affiliation(s)
- R A Samy
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India.
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Iqbal R, Majhy B, Sen AK. Facile Fabrication and Characterization of a PDMS-Derived Candle Soot Coated Stable Biocompatible Superhydrophobic and Superhemophobic Surface. ACS Appl Mater Interfaces 2017; 9:31170-31180. [PMID: 28829562 DOI: 10.1021/acsami.7b09708] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We report a simple, inexpensive, rapid, and one-step method for the fabrication of a stable and biocompatible superhydrophobic and superhemophobic surface. The proposed surface comprises candle soot particles embedded in a mixture of PDMS+n-hexane serving as the base material. The mechanism responsible for the superhydrophobic behavior of the surface is explained, and the surface is characterized based on its morphology and elemental composition, wetting properties, mechanical and chemical stability, and biocompatibility. The effect of %n-hexane in PDMS, the thickness of the PDMS+n-hexane layer (in terms of spin coating speed) and sooting time on the wetting property of the surface is studied. The proposed surface exhibits nanoscale surface asperities (average roughness of 187 nm), chemical compositions of soot particles, very high water and blood repellency along with excellent mechanical and chemical stability and excellent biocompatibility against blood sample and biological cells. The water contact angle and roll-off angle is measured as 160° ± 1° and 2°, respectively, and the blood contact angle is found to be 154° ± 1°, which indicates that the surface is superhydrophobic and superhemophobic. The proposed superhydrophobic and superhemophobic surface offers significantly improved (>40%) cell viability as compared to glass and PDMS surfaces.
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Affiliation(s)
- R Iqbal
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
| | - B Majhy
- 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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Snodgrass C, A'Hearn MF, Aceituno F, Afanasiev V, Bagnulo S, Bauer J, Bergond G, Besse S, Biver N, Bodewits D, Boehnhardt H, Bonev BP, Borisov G, Carry B, Casanova V, Cochran A, Conn BC, Davidsson B, Davies JK, de León J, de Mooij E, de Val-Borro M, Delacruz M, DiSanti MA, Drew JE, Duffard R, Edberg NJT, Faggi S, Feaga L, Fitzsimmons A, Fujiwara H, Gibb EL, Gillon M, Green SF, Guijarro A, Guilbert-Lepoutre A, Gutiérrez PJ, Hadamcik E, Hainaut O, Haque S, Hedrosa R, Hines D, Hopp U, Hoyo F, Hutsemékers D, Hyland M, Ivanova O, Jehin E, Jones GH, Keane JV, Kelley MSP, Kiselev N, Kleyna J, Kluge M, Knight MM, Kokotanekova R, Koschny D, Kramer EA, López-Moreno JJ, Lacerda P, Lara LM, Lasue J, Lehto HJ, Levasseur-Regourd AC, Licandro J, Lin ZY, Lister T, Lowry SC, Mainzer A, Manfroid J, Marchant J, McKay AJ, McNeill A, Meech KJ, Micheli M, Mohammed I, Monguió M, Moreno F, Muñoz O, Mumma MJ, Nikolov P, Opitom C, Ortiz JL, Paganini L, Pajuelo M, Pozuelos FJ, Protopapa S, Pursimo T, Rajkumar B, Ramanjooloo Y, Ramos E, Ries C, Riffeser A, Rosenbush V, Rousselot P, Ryan EL, Santos-Sanz P, Schleicher DG, Schmidt M, Schulz R, Sen AK, Somero A, Sota A, Stinson A, Sunshine JM, Thompson A, Tozzi GP, Tubiana C, Villanueva GL, Wang X, Wooden DH, Yagi M, Yang B, Zaprudin B, Zegmott TJ. The 67P/Churyumov-Gerasimenko observation campaign in support of the Rosetta mission. Philos Trans A Math Phys Eng Sci 2017; 375:rsta.2016.0249. [PMID: 28554971 PMCID: PMC5454223 DOI: 10.1098/rsta.2016.0249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/21/2016] [Indexed: 05/15/2023]
Abstract
We present a summary of the campaign of remote observations that supported the European Space Agency's Rosetta mission. Telescopes across the globe (and in space) followed comet 67P/Churyumov-Gerasimenko from before Rosetta's arrival until nearly the end of the mission in September 2016. These provided essential data for mission planning, large-scale context information for the coma and tails beyond the spacecraft and a way to directly compare 67P with other comets. The observations revealed 67P to be a relatively 'well-behaved' comet, typical of Jupiter family comets and with activity patterns that repeat from orbit to orbit. Comparison between this large collection of telescopic observations and the in situ results from Rosetta will allow us to better understand comet coma chemistry and structure. This work is just beginning as the mission ends-in this paper, we present a summary of the ground-based observations and early results, and point to many questions that will be addressed in future studies.This article is part of the themed issue 'Cometary science after Rosetta'.
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Affiliation(s)
- C Snodgrass
- School of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - M F A'Hearn
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - F Aceituno
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - V Afanasiev
- Special Astrophysical Observatory, Russian Academy of Sciences, Nizhny Arkhyz, Russia
| | - S Bagnulo
- Armagh Observatory, College Hill, Armagh BT61 9DG, UK
| | - J Bauer
- Jet Propulsion Laboratory, M/S 183-401, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - G Bergond
- Centro Astronómico Hispano-Alemán, Calar Alto, CSIC-MPG, Sierra de los Filabres-04550 Gérgal (Almería), Spain
| | - S Besse
- ESA/ESAC, PO Box 78, 28691 Villanueva de la Cañada, Spain
| | - N Biver
- LESIA, Observatoire de Paris, CNRS, UPMC Univ. Paris 06, Univ. Paris-Diderot, 5 Place J. Janssen, 92195 Meudon Pricipal Cedex, France
| | - D Bodewits
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - H Boehnhardt
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - B P Bonev
- Department of Physics, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA
| | - G Borisov
- Armagh Observatory, College Hill, Armagh BT61 9DG, UK
- Institute of Astronomy and National Astronomical Observatory, 72 Tsarigradsko Chaussée Boulevard, BG-1784 Sofia, Bulgaria
| | - B Carry
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Lagrange, France
- IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Lille, France
| | - V Casanova
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - A Cochran
- University of Texas Austin/McDonald Observatory, 1 University Station, Austin, TX 78712, USA
| | - B C Conn
- Research School of Astronomy and Astrophysics, The Australian National University, Canberra, Australian Capital Territory, Australia
- Gemini Observatory, Recinto AURA, Colina El Pino s/n, Casilla 603, La Serena, Chile
| | - B Davidsson
- Jet Propulsion Laboratory, M/S 183-401, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - J K Davies
- The UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
| | - J de León
- Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, 38205 La Laguna, Spain
- Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
| | - E de Mooij
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, UK
| | - M de Val-Borro
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
- NASA Goddard Space Flight Center, Astrochemistry Laboratory, Code 693.0, Greenbelt, MD 20771, USA
- Department of Physics, The Catholic University of America, Washington, DC 20064, USA
| | - M Delacruz
- Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
| | - M A DiSanti
- NASA Goddard Space Flight Center, Astrochemistry Laboratory, Code 693.0, Greenbelt, MD 20771, USA
| | - J E Drew
- School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
| | - R Duffard
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - N J T Edberg
- Swedish Institute of Space Physics, Ångströmlaboratoriet, Lägerhyddsvägen 1, 751 21 Uppsala, Sweden
| | - S Faggi
- INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50 125 Firenze, Italy
| | - L Feaga
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - A Fitzsimmons
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, UK
| | - H Fujiwara
- Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720, USA
| | - E L Gibb
- Department of Physics and Astronomy, University of Missouri - St. Louis, St. Louis, MO 63121, USA
| | - M Gillon
- Institut d'Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, 4000 Liège, Belgium
| | - S F Green
- School of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - A Guijarro
- Centro Astronómico Hispano-Alemán, Calar Alto, CSIC-MPG, Sierra de los Filabres-04550 Gérgal (Almería), Spain
| | - A Guilbert-Lepoutre
- Institut UTINAM, UMR 6213 CNRS-Université de Franche Comté, Besançon, France
| | - P J Gutiérrez
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - E Hadamcik
- CNRS/INSU; UPMC (Sorbonne Univ.); UVSQ (UPSay); LATMOS-IPSL, 11 Bld d'Alembert, 78280 Guyancourt, France
| | - O Hainaut
- European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
| | - S Haque
- Department of Physics, University of the West Indies, St Augustine, Trinidad, West Indies
| | - R Hedrosa
- Centro Astronómico Hispano-Alemán, Calar Alto, CSIC-MPG, Sierra de los Filabres-04550 Gérgal (Almería), Spain
| | - D Hines
- Space Telescope Science Institute, Baltimore, MD 21218, USA
| | - U Hopp
- University Observatory, Ludwig-Maximilian-University Munich, Scheiner Strasse 1, 81679 Munich, Germany
| | - F Hoyo
- Centro Astronómico Hispano-Alemán, Calar Alto, CSIC-MPG, Sierra de los Filabres-04550 Gérgal (Almería), Spain
| | - D Hutsemékers
- Institut d'Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, 4000 Liège, Belgium
| | - M Hyland
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, UK
| | - O Ivanova
- Astronomical Institute of the Slovak Academy of Sciences, 05960 Tatranská Lomnica, Slovak Republic
| | - E Jehin
- Institut d'Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, 4000 Liège, Belgium
| | - G H Jones
- Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT, UK
- The Centre for Planetary Sciences at UCL/Birkbeck, Gower Street, London WC1E 6BT, UK
| | - J V Keane
- Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
| | - M S P Kelley
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - N Kiselev
- Main Astronomical Observatory of National Academy of Sciences, Kyiv, UKraine
| | - J Kleyna
- Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
| | - M Kluge
- University Observatory, Ludwig-Maximilian-University Munich, Scheiner Strasse 1, 81679 Munich, Germany
| | - M M Knight
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - R Kokotanekova
- School of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - D Koschny
- Research and Scientific Support Department, European Space Agency, 2201 Noordwijk, The Netherlands
| | - E A Kramer
- Jet Propulsion Laboratory, M/S 183-401, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - J J López-Moreno
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - P Lacerda
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, UK
| | - L M Lara
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - J Lasue
- Université de Toulouse, UPS-OMP, IRAP-CNRS, Toulouse, France
| | - H J Lehto
- Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
| | - A C Levasseur-Regourd
- UPMC (Sorbonne Univ.); UVSQ (UPSay); CNRS/INSU; LATMOS-IPSL, BC 102, 4 Place Jussieu, 75005 Paris, France
| | - J Licandro
- Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, 38205 La Laguna, Spain
- Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
| | - Z Y Lin
- Graduate Institute of Astronomy, National Central University, No. 300 Zhongda Road, Zhongli District, Taoyuan City, 320 Taiwan
| | - T Lister
- Las Cumbres Observatory, 6740 Cortona Drive, Ste. 102, Goleta, CA 93117, USA
| | - S C Lowry
- Centre for Astrophysics and Planetary Science, School of Physical Sciences, The University of Kent, Canterbury CT2 7NH, UK
| | - A Mainzer
- Jet Propulsion Laboratory, M/S 183-401, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - J Manfroid
- Institut d'Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, 4000 Liège, Belgium
| | - J Marchant
- Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5RF, UK
| | - A J McKay
- University of Texas Austin/McDonald Observatory, 1 University Station, Austin, TX 78712, USA
- NASA Goddard Space Flight Center, Astrochemistry Laboratory, Code 693.0, Greenbelt, MD 20771, USA
| | - A McNeill
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, UK
| | - K J Meech
- Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
| | - M Micheli
- ESA SSA-NEO Coordination Centre, Frascati (RM), Italy
| | - I Mohammed
- Caribbean Institute of Astronomy, Trinidad, West Indies
| | - M Monguió
- School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
| | - F Moreno
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - O Muñoz
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - M J Mumma
- NASA Goddard Space Flight Center, Astrochemistry Laboratory, Code 693.0, Greenbelt, MD 20771, USA
| | - P Nikolov
- Institute of Astronomy and National Astronomical Observatory, 72 Tsarigradsko Chaussée Boulevard, BG-1784 Sofia, Bulgaria
| | - C Opitom
- Institut d'Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, 4000 Liège, Belgium
- European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
| | - J L Ortiz
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - L Paganini
- NASA Goddard Space Flight Center, Astrochemistry Laboratory, Code 693.0, Greenbelt, MD 20771, USA
| | - M Pajuelo
- IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Lille, France
- Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Apartado 1761, Lima, Perú
| | - F J Pozuelos
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
- Institut d'Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, 4000 Liège, Belgium
| | - S Protopapa
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - T Pursimo
- Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Santa Cruz de Tenerife, Spain
| | - B Rajkumar
- Department of Physics, University of the West Indies, St Augustine, Trinidad, West Indies
| | - Y Ramanjooloo
- Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
| | - E Ramos
- Centro Astronómico Hispano-Alemán, Calar Alto, CSIC-MPG, Sierra de los Filabres-04550 Gérgal (Almería), Spain
| | - C Ries
- University Observatory, Ludwig-Maximilian-University Munich, Scheiner Strasse 1, 81679 Munich, Germany
| | - A Riffeser
- University Observatory, Ludwig-Maximilian-University Munich, Scheiner Strasse 1, 81679 Munich, Germany
| | - V Rosenbush
- Main Astronomical Observatory of National Academy of Sciences, Kyiv, UKraine
| | - P Rousselot
- University of Franche-Comté, Observatoire des Sciences de l'Univers THETA, Institut UTINAM - UMR CNRS 6213, BP 1615, 25010 Besançon Cedex, France
| | - E L Ryan
- SETI Institute, 189 Bernardo Avenue Suite 200, Mountain View, CA 94043, USA
| | - P Santos-Sanz
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - D G Schleicher
- Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff, AZ 86001, USA
| | - M Schmidt
- University Observatory, Ludwig-Maximilian-University Munich, Scheiner Strasse 1, 81679 Munich, Germany
| | - R Schulz
- Scientific Support Office, European Space Agency, 2201 AZ Noordwijk, The Netherlands
| | - A K Sen
- Department of Physics, Assam University, Silchar 788011, India
| | - A Somero
- Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
| | - A Sota
- Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - A Stinson
- Armagh Observatory, College Hill, Armagh BT61 9DG, UK
| | - J M Sunshine
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
| | - A Thompson
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, UK
| | - G P Tozzi
- INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50 125 Firenze, Italy
| | - C Tubiana
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - G L Villanueva
- NASA Goddard Space Flight Center, Astrochemistry Laboratory, Code 693.0, Greenbelt, MD 20771, USA
| | - X Wang
- Yunnan Observatories, CAS, China, PO Box 110, Kunming 650011, Yunnan Province, People's Republic of China
- Key Laboratory for the Structure and Evolution of Celestial Objects, CAS, Kunming 650011, People's Republic of China
| | - D H Wooden
- NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035-1000, USA
| | - M Yagi
- National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
| | - B Yang
- European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
| | - B Zaprudin
- Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
| | - T J Zegmott
- Centre for Astrophysics and Planetary Science, School of Physical Sciences, The University of Kent, Canterbury CT2 7NH, UK
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Iqbal R, Dhiman S, Sen AK, Shen AQ. Dynamics of a Water Droplet over a Sessile Oil Droplet: Compound Droplets Satisfying a Neumann Condition. Langmuir 2017; 33:5713-5723. [PMID: 28499091 DOI: 10.1021/acs.langmuir.6b04621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the dynamics of compound droplets with a denser liquid (water) droplet over a less dense sessile droplet (mineral oil) that satisfies the Neumann condition. For a fixed size of an oil droplet, depending on the size of the water droplet, either it attains the axisymmetric position or tends to migrate toward the edge of the oil droplet. For a water droplet-to-oil droplet at volume ratio Vw/Vo ≥ 0.05, stable axisymmetric configuration is achieved; for Vw/Vo < 0.05, migration of water droplet is observed. The stability and migration of water droplets of size above and below critical size, respectively, are explained using the force balance at the three-phase contact line and film tension. The larger and smaller droplets that initially attain the axisymmetric position or some radial position, respectively, evaporate continuously and thus migrate toward the edge of the oil droplet. The radial location and migration of the water droplets of different initial sizes with respect to time are studied. Experiments with water droplets on a flat oil-air interface did not show migration, which signified the role of the curved oil-air interface for droplet migration. Finally, coalescence of water droplets of size above the critical size at the axisymmetric position is demonstrated. Our compound droplet studies could be beneficial for applications involving droplet transport where contamination due to direct contact and pinning of droplets on solid surfaces is of concern. Migration and coalescence of water droplets on curved oil-air interfaces could open new frontiers in chemical and biological applications including multiphase processing and biological interaction of cells and atmospheric chemistry.
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Affiliation(s)
- R Iqbal
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
| | - S Dhiman
- 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
| | - Amy Q Shen
- Micro/Bio/Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate University , Okinawa 904-0495, Japan
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Maria MS, Rakesh PE, Chandra TS, Sen AK. Capillary flow-driven microfluidic device with wettability gradient and sedimentation effects for blood plasma separation. Sci Rep 2017; 7:43457. [PMID: 28256564 PMCID: PMC5335260 DOI: 10.1038/srep43457] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 01/24/2017] [Indexed: 12/12/2022] Open
Abstract
We report a capillary flow-driven microfluidic device for blood-plasma separation that comprises a cylindrical well between a pair of bottom and top channels. Exposure of the well to oxygen-plasma creates wettability gradient on its inner surface with its ends hydrophilic and middle portion hydrophobic. Due to capillary action, sample blood self-infuses into bottom channel and rises up the well. Separation of plasma occurs at the hydrophobic patch due to formation of a ‘self-built-in filter’ and sedimentation. Capillary velocity is predicted using a model and validated using experimental data. Sedimentation of RBCs is explained using modified Steinour’s model and correlation between settling velocity and liquid concentration is found. Variation of contact angle on inner surface of the well is characterized and effects of well diameter and height and dilution ratio on plasma separation rate are investigated. With a well of 1.0 mm diameter and 4.0 mm height, 2.0 μl of plasma was obtained (from <10 μl whole blood) in 15 min with a purification efficiency of 99.9%. Detection of glucose was demonstrated with the plasma obtained. Wetting property of channels was maintained by storing in DI water under vacuum and performance of the device was found to be unaffected over three weeks.
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Affiliation(s)
- M Sneha Maria
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.,Department of Biotechnology, Indian Institute of Technology Madras, Chennai-600036, India
| | - P E Rakesh
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
| | - T S Chandra
- Department of Biotechnology, 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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Jayaprakash KS, Banerjee U, Sen AK. Dynamics of rigid microparticles at the interface of co-flowing immiscible liquids in a microchannel. J Colloid Interface Sci 2017; 493:317-326. [PMID: 28119242 DOI: 10.1016/j.jcis.2017.01.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/07/2017] [Accepted: 01/10/2017] [Indexed: 11/16/2022]
Abstract
We report the dynamical migration behavior of rigid polystyrene microparticles at an interface of co-flowing streams of primary CP1 (aqueous) and secondary CP2 (oils) immiscible phases at low Reynolds numbers (Re) in a microchannel. The microparticles initially suspended in the CP1 either continue to flow in the bulk CP1 or migrate across the interface into CP2, when the stream width of the CP1 approaches the diameter of the microparticles. Experiments were performed with different secondary phases and it is found that the migration criterion depends on the sign of the spreading parameter S and the presence of surfactant at the interface. To substantiate the migration criterion, experiments were also carried out by suspending the microparticles in CP2 (oil phase). Our study reveals that in case of aqueous-silicone oil combination, the microparticles get attached to the interface since S<0 and the three phase contact angle, θ>90°. For complete detachment of microparticles from the interface into the secondary phase, additional energy ΔG is needed. We discuss the role of interfacial perturbation, which causes detachment of microparticles from the interface. In case of mineral and olive oils, the surfactants present at the interface prevents attachment of the microparticles to the interface due to the repulsive disjoining pressure. Finally, using a aqueous-silicone oil system, we demonstrate size based sorting of microparticles of size 25μm and 15μm respectively from that of 15μm and 10μm and study the variation of separation efficiency η with the ratio of the width of the aqueous stream to the diameter of the microparticles ρ.
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Affiliation(s)
- K S Jayaprakash
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - U Banerjee
- 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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George D, Damodara S, Iqbal R, Sen AK. Flotation of Denser Liquid Drops on Lighter Liquids in Non-Neumann Condition: Role of Line Tension. Langmuir 2016; 32:10276-10283. [PMID: 27643710 DOI: 10.1021/acs.langmuir.6b02771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Flotation of a denser liquid drop on lighter liquid has been explained earlier via the Neumann triangle. We demonstrate the flotation of a denser liquid (water) drop on a lighter liquid in a pair that does not satisfy the Neumann triangle. We attribute this newly studied phenomenon to the role of line tension τ which prevents the water droplet from complete engulfment. A simple model is used to explain the underlying physics and to obtain critical line tension value for stable flotation. We establish line tension values for different liquids with water and show possible heterogeneous nucleation that contributes toward the variance of line tension values.
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Affiliation(s)
- D George
- Indian Institute of Technology Madras , Chennai 600036, India
| | - S Damodara
- Indian Institute of Technology Madras , Chennai 600036, India
| | - R Iqbal
- Indian Institute of Technology Madras , Chennai 600036, India
| | - A K Sen
- Indian Institute of Technology Madras , Chennai 600036, India
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Maria MS, Rakesh PE, Chandra TS, Sen AK. Capillary flow of blood in a microchannel with differential wetting for blood plasma separation and on-chip glucose detection. Biomicrofluidics 2016; 10:054108. [PMID: 27703594 PMCID: PMC5035299 DOI: 10.1063/1.4962874] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/03/2016] [Indexed: 05/08/2023]
Abstract
We report capillary flow of blood in a microchannel with differential wetting for the separation of a plasma from sample blood and subsequent on-chip detection of glucose present in a plasma. A rectangular polydimethylsiloxane microchannel with hydrophilic walls (on three sides) achieved by using oxygen plasma exposure enables capillary flow of blood introduced at the device inlet through the microchannel. A hydrophobic region (on all four sides) in the microchannel impedes the flow of sample blood, and the accumulated blood cells at the region form a filter to facilitate the separation of a plasma. The modified wetting property of the walls and hence the device performance could be retained for a few weeks by covering the channels with deionised water. The effects of the channel cross-section, exposure time, waiting time, and location and length of the hydrophobic region on the volume of the collected plasma are studied. Using a channel cross-section of 1000 × 400 μm, an exposure time of 2 min, a waiting time of 10 min, and a hydrophobic region of width 1.0 cm located at 10 mm from the device inlet, 450 nl of plasma was obtained within 15 min. The performance of the device was found to be unaffected (provides 450 nl of plasma in 15 min) even after 15 days. The purification efficiency and plasma recovery of the device were measured and found to be comparable with that obtained using the conventional centrifugation process. Detection of glucose at different concentrations in whole blood of normal and diabetic patients was performed (using 5 μl of sample blood within 15 min) to demonstrate the compatibility of the device with integrated detection modules.
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Affiliation(s)
| | - P E Rakesh
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600036, India
| | - T S Chandra
- Department of Biotechnology, 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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Jayaprakash KS, Banerjee U, Sen AK. Dynamics of Aqueous Droplets at the Interface of Coflowing Immiscible Oils in a Microchannel. Langmuir 2016; 32:2136-43. [PMID: 26812441 DOI: 10.1021/acs.langmuir.5b04116] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the dynamics of aqueous droplets of different size and viscosity at the interface of a coflowing stream of immiscible oils (i.e., primary and secondary continuous phases) in a microchannel, at low Re. The lateral migration of droplets introduced into the primary continuous phase toward the interface and subsequent selective migration of droplets across the interface into the secondary continuous phase is investigated. The interplay between the competing noninertial lift and interfacial tension forces, which govern the interfacial migration of the droplets, is presented and discussed. The velocity and strain rate profiles, and interface location, which are critical for calculating the lift force and migration behavior of droplets, are presented. The trajectories of droplets of different size and viscosity in the primary continuous phase are obtained for different interface locations. During interfacial migration, the deformation behavior of droplets of different viscosities is studied. Finally, sorting of droplets based on size contrast is demonstrated and sorting efficiency is found. A new paradigm of migration and sorting of droplets is reported, which could find importance in chemical and biological applications.
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Affiliation(s)
- K S Jayaprakash
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai-600036, India
| | - U Banerjee
- 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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Abstract
This paper reports the characterization and sorting of cells based on stiffness contrast. A microfluidic device with focusing and spacing control for stiffness based sorting of cells is designed, fabricated and demonstrated.
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Affiliation(s)
- P. Sajeesh
- 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
| | - M. Doble
- Department of Biotechnology
- 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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Sajeesh P, Manasi S, Doble M, Sen AK. A microfluidic device with focusing and spacing control for resistance-based sorting of droplets and cells. Lab Chip 2015; 15:3738-3748. [PMID: 26235533 DOI: 10.1039/c5lc00598a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper reports a novel hydrodynamic technique for sorting of droplets and cells based on size and deformability. The device comprises two modules: a focusing and spacing control module and a sorting module. The focusing and spacing control module enables focusing of objects present in a sample onto one of the side walls of a channel with controlled spacing between them using a sheath fluid. A 3D analytical model is developed to predict the sheath-to-sample flow rate ratio required to facilitate single-file focusing and maintain the required spacing between a pair of adjacent objects. Experiments are performed to demonstrate focusing and spacing control of droplets (size 5-40 μm) and cells (HL60, size 10-25 μm). The model predictions compare well with experimental data in terms of focusing and spacing control within 9%. In the sorting module, the main channel splits into two branch channels (straight and side branches) with the flow into these two channels separated by a "dividing streamline". A sensing channel and a bypass channel control the shifting of the dividing streamline depending on the object size and deformability. While resistance offered by individual droplets of different sizes has been studied in our previous work (P. Sajeesh, M. Doble and A. K. Sen, Biomicrofluidics, 2014, 8, 1-23), here we present resistance of individual cells (HL60) as a function of size. A theoretical model is developed and used for the design of the sorter. Experiments are performed for size-based sorting of droplets (sizes 25 and 40 μm, 10 and 15 μm) and HL60 cells (sizes 11 μm and 19 μm) and deformability-based sorting of droplets (size 10 ± 1.0 μm) and polystyrene microbeads (size 10 ± 0.2 μm). The performance of the device for size- and deformability-based sorting is characterized in terms of sorting efficiency. The proposed device could be potentially used as a diagnostic tool for sorting of larger tumour cells from smaller leukocytes.
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Affiliation(s)
- P Sajeesh
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
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Anoop R, Sen AK. Capillary flow enhancement in rectangular polymer microchannels with a deformable wall. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:013024. [PMID: 26274286 DOI: 10.1103/physreve.92.013024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Indexed: 06/04/2023]
Abstract
We report the capillary flow enhancement in rectangular polymer microchannels, when one of the channel walls is a deformable polymer membrane. We provide detailed insight into the physics of elastocapillary interaction between the capillary flow and elastic membrane, which leads to significant improvements in capillary flow performance. As liquid flows by capillary action in such channels, the deformable wall deflects inwards due to the Young-Laplace pressure drop across the liquid meniscus. This, in turn, decreases the radius of curvature of the meniscus and increases the driving capillary pressure. A theoretical model is proposed to predict the resultant increase in filling speed and rise height, respectively, in deformable horizontal and vertical microchannels having large aspect ratios. A non-dimensional parameter J, which represents the ratio of the capillary force to the mechanical restoring force, is identified to quantify the elastocapillary effects in terms of the improvement in filling speed (for J>0.238) and the condition for channel collapse (J>1). The theoretical predictions show good agreement with experimental data obtained using deformable rectangular poly(dimethylsiloxane) microchannels. Both model predictions and experimental data show that over 15% improvement in the Washburn coefficient in horizontal channels, and over 30% improvement in capillary rise height in vertical channels, are possible prior to channel collapse. The proposed technique of using deformable membranes as channel walls is a viable method for capillary flow enhancement in microfluidic devices.
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Affiliation(s)
- R Anoop
- 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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Sajeesh P, Doble M, Sen AK. Hydrodynamic resistance and mobility of deformable objects in microfluidic channels. Biomicrofluidics 2014; 8:054112. [PMID: 25538806 PMCID: PMC4222326 DOI: 10.1063/1.4897332] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/25/2014] [Indexed: 05/12/2023]
Abstract
This work reports experimental and theoretical studies of hydrodynamic behaviour of deformable objects such as droplets and cells in a microchannel. Effects of mechanical properties including size and viscosity of these objects on their deformability, mobility, and induced hydrodynamic resistance are investigated. The experimental results revealed that the deformability of droplets, which is quantified in terms of deformability index (D.I.), depends on the droplet-to-channel size ratio [Formula: see text] and droplet-to-medium viscosity ratio [Formula: see text]. Using a large set of experimental data, for the first time, we provide a mathematical formula that correlates induced hydrodynamic resistance of a single droplet [Formula: see text] with the droplet size [Formula: see text] and viscosity [Formula: see text]. A simple theoretical model is developed to obtain closed form expressions for droplet mobility [Formula: see text] and [Formula: see text]. The predictions of the theoretical model successfully confront the experimental results in terms of the droplet mobility [Formula: see text] and induced hydrodynamic resistance [Formula: see text]. Numerical simulations are carried out using volume-of-fluid model to predict droplet generation and deformation of droplets of different size ratio [Formula: see text] and viscosity ratio [Formula: see text], which compare well with that obtained from the experiments. In a novel effort, we performed experiments to measure the bulk induced hydrodynamic resistance [Formula: see text] of different biological cells (yeast, L6, and HEK 293). The results reveal that the bulk induced hydrodynamic resistance [Formula: see text] is related to the cell concentration and apparent viscosity of the cells.
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Affiliation(s)
- P Sajeesh
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai-600036, India and Department of Biotechnology, Indian Institute of Technology Madras , Chennai-600036, India
| | - M Doble
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai-600036, India and Department of Biotechnology, Indian Institute of Technology Madras , Chennai-600036, India
| | - A K Sen
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai-600036, India and Department of Biotechnology, Indian Institute of Technology Madras , Chennai-600036, India
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48
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Sokolov V, Sen AK. Analogous saturation mechanisms of the ion and electron temperature gradient drift wave turbulence. Phys Rev Lett 2014; 113:095001. [PMID: 25215988 DOI: 10.1103/physrevlett.113.095001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Indexed: 06/03/2023]
Abstract
New experimental results and theoretical arguments indicate that a novel saturation mechanism of the electron temperature gradient modes is related to its coupling to a damped ion acoustic mode. The experimental bicoherence data show multimode coupling between two high frequency radial harmonics of electron temperature gradient in the vicinity of (∼2 MHz) and one low frequency ion acoustic (∼45 kHz) mode. A unique feedback diagnostic also verifies this coupling. It is pointed out that a near identical mechanism is responsible for ITG mode saturation [V. Sokolov, and A. K. Sen, Phys. Rev. Lett. 92, 165002 (2004)], indicating its plausible generic nature.
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Affiliation(s)
- V Sokolov
- Plasma Research Laboratory, Columbia University, New York, New York 10027, USA
| | - A K Sen
- Plasma Research Laboratory, Columbia University, New York, New York 10027, USA
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Swain P, Nayak SK, Sasmal A, Behera T, Barik SK, Swain SK, Mishra SS, Sen AK, Das JK, Jayasankar P. Antimicrobial activity of metal based nanoparticles against microbes associated with diseases in aquaculture. World J Microbiol Biotechnol 2014; 30:2491-502. [PMID: 24888333 DOI: 10.1007/s11274-014-1674-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 05/20/2014] [Indexed: 12/18/2022]
Abstract
The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag-TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.
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Affiliation(s)
- P Swain
- Fish Health Management Division, Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, 751002, India,
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Abstract
An experimental study on isotachophoresis (ITP) in which an emulsion is used as leading electrolyte (LE) is reported. The study aims at giving an overview about the transport and flow phenomena occurring in that context. Generally, it is observed that the oil droplets initially dispersed in the LE are collected at the ITP transition zone and advected along with it. The detailed behavior at the transition zone depends on whether or not surfactants (polyvinylpyrrolidon, PVP) are added to the electrolytes. In a system without surfactants, coalescence is observed between the droplets collected at the ITP transition zone. After having achieved a certain size, the droplets merge with the channel walls, leaving an oil film behind. In systems with PVP, coalescence is largely suppressed and no merging of droplets with the channel walls is observed. Instead, at the ITP transition zone, a droplet agglomerate of increasing size is formed. In the initial stages of the ITP experiments, two counter rotating vortices are formed inside the terminating electrolyte. The vortex formation is qualitatively explained based on a hydrodynamic instability triggered by fluctuations of the number density of oil droplets.
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Affiliation(s)
- G Goet
- Institute for Nano- and Microfluidics, Center of Smart Interfaces, TU Darmstadt, 64287 Darmstadt, Germany
| | - T Baier
- Institute for Nano- and Microfluidics, Center of Smart Interfaces, TU Darmstadt, 64287 Darmstadt, Germany
| | - S Hardt
- Institute for Nano- and Microfluidics, Center of Smart Interfaces, TU Darmstadt, 64287 Darmstadt, Germany
| | - A K Sen
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
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