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Mohseni A, Azimi AA, Bijarchi MA. Formation of magnetic double emulsions under steady and variable magnetic fields from a 3D-printed coaxial capillary device. Anal Chim Acta 2024; 1309:342573. [PMID: 38772651 DOI: 10.1016/j.aca.2024.342573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 03/28/2024] [Accepted: 04/01/2024] [Indexed: 05/23/2024]
Abstract
BACKGROUND Double emulsions (DEs) have attracted researchers' attention to be utilized as a promising platform in biomedical and chemical applications. Several actuation mechanisms have been proposed for the generation of DEs. The conventional DE formation approaches (e.g. two-stage emulsification) suffer from low monodispersity. The electric actuation (i.e. coaxial electrospray technology) has been demonstrated as a controllable method for the DE formation, while the capability of magnetic actuation has not been studied yet. RESULT In the present study, the generation of ferrofluid double emulsions (FDEs), made from water-based ferrofluid as a core and oil as a shell, under the magnetic actuation of a permanent magnet with a steady magnetic field and an electromagnet with DC and pulse width modulation (PWM) magnetic fields was investigated with a simple controllable setup fabricated using 3D printing. The effect of various parameters affecting the FDE formation, such as the fluid flow rates, the magnetic field type, the magnetic flux density, and the PWM frequency and duty cycle, on the FDE formation characteristics, including the inner and outer equivalent diameters, and the formation frequency was studied. Under the steady magnetic field, two regimes of the FDE formation were identified: inertia-dominated and magnet-dominated. SIGNIFICANCE Wireless power-free magnetic actuation provides better control over the FDE formation, enhancing this process by increasing the FDE formation frequency with high monodispersity. The PWM magnetic field offers excellent controllability over the FDE formation with low-volume or no, in some cases, satellite droplets by tuning the PWM frequency and the duty cycle.
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Affiliation(s)
- Alireza Mohseni
- Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Ali Abbas Azimi
- Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Mohamad Ali Bijarchi
- Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
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Dayyani H, Mohseni A, Bijarchi MA. Dynamic behavior of floating magnetic liquid marbles under steady and pulse-width-modulated magnetic fields. LAB ON A CHIP 2024; 24:2005-2016. [PMID: 38390638 DOI: 10.1039/d3lc00578j] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Liquid marbles show promising potential for digital microfluidic devices due to their lower friction with the platform surface than non-covered droplets. In this study, the manipulation of a biocompatible magnetic liquid marble with a magnetic shell (LMMS) is experimentally studied. The movement of the floating LMMS on the water surface, which is actuated by DC and pulse width modulation (PWM) magnetic fields, is investigated under the influence of various parameters, including the LMMS volume, the initial distance of the LMMS from the magnetic coil tip, the magnetic coil current, the PWM frequency and its duty cycle. The LMMS has a shorter travel time to the magnetic coil tip under a DC magnetic field by increasing the magnetic coil current, decreasing the initial distance and its volume. In the PWM mode, these parameters show similar behavior; moreover, increasing the PWM duty cycle and decreasing the PWM frequency shorten the travel time. It is demonstrated that actuation by a PWM magnetic field with step-by-step movement provides better control over manipulation of the floating magnetic marble. The dynamic behavior of an LMMS is compared to a ferrofluid marble (FM), which is formed using a ferrofluid instead of water as its core. It is observed that the LMMS has a lower velocity than the FM.
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Affiliation(s)
- Hossein Dayyani
- Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
| | - Alireza Mohseni
- Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
| | - Mohamad Ali Bijarchi
- Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
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Mohammadrashidi M, Bijarchi MA, Shafii MB, Taghipoor M. Experimental and Theoretical Investigation on the Dynamic Response of Ferrofluid Liquid Marbles to Steady and Pulsating Magnetic Fields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:2246-2259. [PMID: 36722776 DOI: 10.1021/acs.langmuir.2c02811] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Liquid marbles are droplets enwrapped by a layer of hydrophobic micro/nanoparticles. Due to the isolation of fluid from its environment, reduction in evaporation rate, low friction with the surfaces, and capability of manipulation even on hydrophilic surfaces, liquid marbles have attracted the attention of researchers in digital microfluidics. This study investigates the manipulation of ferrofluid liquid marbles (FLMs) under DC and pulse width-modulated (PWM) magnetic fields generated by an electromagnet for the first time. At first, the threshold of the magnetic field for manipulating these FLMs is studied. Afterward, the dynamic response of the FLMs to the DC magnetic field for different FLM volumes, coil currents, and initial distances of FLM from the coil is studied, and a theoretical model is proposed. By applying the PWM magnetic field, it is possible to gain more control over the manipulation of the FLMs on the surface and adjust their position more accurately. Results indicate that with a decrease in FLM volume, coil current, and duty cycle, the FLM step length decreases; hence, FLM manipulation is more precise. Under the PWM magnetic field, it is observed that FLM movement is not synchronous with the generated pulse, and even after the coil is turned off, FLMs keep their motion. In the end, with proper adjustment of the electromagnet pulse width, launching of FLMs at a distance farther than the coil is observed.
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Affiliation(s)
- Mahbod Mohammadrashidi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran1458889694, Iran
| | - Mohamad Ali Bijarchi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran1458889694, Iran
| | - Mohammad Behshad Shafii
- Department of Mechanical Engineering, Sharif University of Technology, Tehran1458889694, Iran
| | - Mojtaba Taghipoor
- Department of Mechanical Engineering, Sharif University of Technology, Tehran1458889694, Iran
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Huang X, Saadat M, Ali Bijarchi M, Behshad Shafii M. Ferrofluid double emulsion generation and manipulation under magnetic fields. Chem Eng Sci 2023. [DOI: 10.1016/j.ces.2023.118519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Azizian P, Mohammadrashidi M, Abbas Azimi A, Bijarchi MA, Shafii MB, Nasiri R. Magnetically Driven Manipulation of Nonmagnetic Liquid Marbles: Billiards with Liquid Marbles. MICROMACHINES 2022; 14:49. [PMID: 36677108 PMCID: PMC9865651 DOI: 10.3390/mi14010049] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/10/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Liquid marbles are droplets encapsulated by a layer of hydrophobic nanoparticles and have been extensively employed in digital microfluidics and lab-on-a-chip systems in recent years. In this study, magnetic liquid marbles were used to manipulate nonmagnetic liquid marbles. To achieve this purpose, a ferrofluid liquid marble (FLM) was employed and attracted toward an electromagnet, resulting in an impulse to a water liquid marble (WLM) on its way to the electromagnet. It was observed that the manipulation of the WLM by the FLM was similar to the collision of billiard balls except that the liquid marbles exhibited an inelastic collision. Taking the FLM as the projectile ball and the WLM as the other target balls, one can adjust the displacement and direction of the WLM precisely, similar to an expert billiard player. Firstly, the WLM displacement can be adjusted by altering the liquid marble volumes, the initial distances from the electromagnet, and the coil current. Secondly, the WLM direction can be adjusted by changing the position of the WLM relative to the connecting line between the FLM center and the electromagnet. Results show that when the FLM or WLM volume increases by five times, the WLM shooting distance approximately increases by 200% and decreases by 75%, respectively.
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Affiliation(s)
- Parnian Azizian
- Department of Mechanical Engineering, Sharif University of Technology, Tehran 11155-9567, Iran
| | - Mahbod Mohammadrashidi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran 11155-9567, Iran
| | - Ali Abbas Azimi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran 11155-9567, Iran
| | - Mohamad Ali Bijarchi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran 11155-9567, Iran
| | - Mohammad Behshad Shafii
- Department of Mechanical Engineering, Sharif University of Technology, Tehran 11155-9567, Iran
| | - Rohollah Nasiri
- Department of Protein Science, Division of Nanobiotechnology, KTH Royal Institute of Technology, 171 65 Solna, Sweden
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On-demand ferrofluid droplet formation with non-linear magnetic permeability in the presence of high non-uniform magnetic fields. Sci Rep 2022; 12:10868. [PMID: 35760843 PMCID: PMC9237107 DOI: 10.1038/s41598-022-14624-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 06/09/2022] [Indexed: 11/08/2022] Open
Abstract
The magnetic actuation of ferrofluid droplets offers an inspiring tool in widespread engineering and biological applications. In this study, the dynamics of ferrofluid droplet generation with a Drop-on-Demand feature under a non-uniform magnetic field is investigated by multiscale numerical modeling. Langevin equation is assumed for ferrofluid magnetic susceptibility due to the strong applied magnetic field. Large and small computational domains are considered. In the larger domain, the magnetic field is obtained by solving Maxwell equations. In the smaller domain, a coupling of continuity, Navier Stokes, two-phase flow, and Maxwell equations are solved by utilizing the magnetic field achieved by the larger domain for the boundary condition. The Finite volume method and coupling of level-set and Volume of Fluid methods are used for solving equations. The droplet formation is simulated in a two-dimensional axisymmetric domain. The method of solving fluid and magnetic equations is validated using a benchmark. Then, ferrofluid droplet formation is investigated experimentally, and the numerical results showed good agreement with the experimental data. The effect of 12 dimensionless parameters, including the ratio of magnetic, gravitational, and surface tension forces, the ratio of the nozzle and magnetic coil dimensions, and ferrofluid to continuous-phase properties ratios are studied. The results showed that by increasing the magnetic Bond number, gravitational Bond number, Ohnesorge number, dimensionless saturation magnetization, initial magnetic susceptibility of ferrofluid, the generated droplet diameter reduces, whereas the formation frequency increases. The same results were observed when decreasing the ferrite core diameter to outer nozzle diameter, density, and viscosity ratios.
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Ferrofluid droplet breakup process and neck evolution under steady and pulse-width modulated magnetic fields. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ajith K, Pillai AS, Enoch IMV, Solomon AB. Effect of magnetic field on the thermophysical properties of low-density ferrofluid with disk-shaped MgFe2O4 nanoparticles. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2020.126083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Bijarchi MA, Dizani M, Honarmand M, Shafii MB. Splitting dynamics of ferrofluid droplets inside a microfluidic T-junction using a pulse-width modulated magnetic field in micro-magnetofluidics. SOFT MATTER 2021; 17:1317-1329. [PMID: 33313630 DOI: 10.1039/d0sm01764g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Micro-magnetofluidics offers a promising tool for better control over the ferrofluid droplet manipulation which has been vastly utilized in biomedical applications in recent years. In this study, the ferrofluid droplet splitting under an asymmetric Pulse-Width-Modulated (PWM) magnetic field in a T-junction is numerically investigated using a finite volume method and VOF two-phase model. By utilizing the PWM magnetic field, two novel regimes of ferrofluid droplet splitting named as Flowing through the Same Branch (FSB) and Double Splitting (DS) have been observed for the first time. In the FSB regime, the daughter droplets move out of the same microchannel outlet, and in the DS regime, the droplet splitting occurs two times which results in generating three daughter droplets. The main problem related to the asymmetric droplet splitting under a steady magnetic field is daughter droplet trapping. By using a PWM magnetic field, this issue is resolved and the trapped/escaped regions are obtained in terms of the duty cycle and dimensionless magnetic field frequency. The effects of six important dimensionless parameters on the splitting ratio, including magnetic Bond number, duty cycle, dimensionless magnetic field frequency, capillary number, dimensionless mother droplet length, and dimensionless dipole position are investigated. The results showed that the splitting ratio increases with increasing magnetic Bond number or duty cycle, or decreasing the dimensionless magnetic field frequency. Eventually, a correlation is offered for the splitting ratio based on the dimensionless variables with an average relative error of 2.67%.
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Affiliation(s)
- Mohamad Ali Bijarchi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
| | - Mahdi Dizani
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
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Bhandari A. Numerical study of time-dependent ferrofluid flow past a cylinder in the presence of stationary magnetic field. SN APPLIED SCIENCES 2021. [DOI: 10.1007/s42452-020-04047-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
AbstractThis work investigates time-dependent ferrofluid flow past in a cylinder in the presence of a 10 kilo-ampere per meter magnetic field. The Reynolds number is about a hundred to keep the laminar flow and it is high enough to form a von Karman vortex street. This study presents the results for the velocity distributions, pressure distributions, lift coefficient, and drag coefficient under the influence of the stationary magnetic field. These results are compared with the flow in the absence of the magnetic field. The presence of the magnetic field diminishes the velocity distributions in the flow due to magnetization force and magnetic field dependent viscosity. This reduction in the velocity reduces the average velocity in the flow and therefore the magnetic field intensity enhances the coefficients of drag and lift. In the presence of the applied magnetic field, the velocity drops from 2.19 to 1.97 m/s at t = 7 s. However, the lift coefficients enhance from 3 m2s2/kg to 3.4 m2s2/kg and the drag coefficient enhances from 0.9 to 3 m2s2/kg. The numerical simulation of the problem is obtained using the finite element method in COMSOL Multiphysics.
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Marin CN, Malaescu I. Experimental and theoretical investigations on thermal conductivity of a ferrofluid under the influence of magnetic field. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2020; 43:61. [PMID: 33006675 DOI: 10.1140/epje/i2020-11986-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
The effect of the strength and orientation of magnetic field with respect to the temperature gradient on the effective thermal conductivity [Formula: see text], in a kerosene-based ferrofluid with magnetite particles is reported. A new theoretical model to explain the experimental dependence [Formula: see text], obtained for both the parallel and perpendicular orientation of the magnetic field, relative to the temperature gradient is proposed, based on the Sillars equation (which is applied for the first time to a ferrofluid in this purpose). For computing [Formula: see text], we have considered that the particle agglomerations, arranged in field-induced microstructures, have ellipsoid forms and the ratio a/b between the major axis and the minor axis of the ellipsoid increases with increasing the magnetic field strength. Using the proposed theoretical model, we established for the first time a semi-empirical relationship between the ratio, a/b and the magnetic field, H, both for parallel and perpendicular H relative to the temperature gradient, determining then the dependence on H of [Formula: see text]. The theoretical results are in agreement with the experimental measurements. The reported results are of great practical importance and show that ferrofluids may be useful for incorporation in magnetic tuneable heat transfer devices or for other potential thermal applications.
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Affiliation(s)
- Catalin N Marin
- West University of Timisoara, Faculty of Physics, Bd. V. Parvan nr. 4, 300223, Timisoara, Romania
| | - Iosif Malaescu
- West University of Timisoara, Faculty of Physics, Bd. V. Parvan nr. 4, 300223, Timisoara, Romania.
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Contact time on inclined superhydrophobic surfaces decorated with parallel macro-ridges. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.124924] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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