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Fang W, Tao Z, Li H, Ma Y, Yin S, Xu T, Wong T, Huang Y. Characteristics of Oil-in-Oil Emulsions under AC Electric Fields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:2268-2277. [PMID: 38221735 DOI: 10.1021/acs.langmuir.3c03404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Emulsions have been applied in a number of industries such as pharmaceutics, cosmetics, and food, which are also of great scientific interest. Although aqueous emulsions are commonly used in our daily life, oil-in-oil (o/o) emulsions also play an irreplaceable role in view of their unique physics and complementary applications. In this paper, we investigate typical behaviors of organic droplets surrounded by organic medium (o/o emulsions) with different functional groups controlled by the AC electric field. Droplet behaviors can be catalogued into five types: namely, "no effect", "movement", "deformation", "interface rupture", and "disorder". We identify the key dimensionless number Wee·Ca, combined with the channel geometry, for characterizing the typical behaviors in silicon oil/1,6-hexanediol diacrylate and mineral oil/1,6-hexanediol diacrylate emulsions. Unlike aqueous emulsion, the Maxwell-Wagner relaxation inhibits the electric effect and leads to an effective frequency, ranging from 0.5 to 3 kHz. The increasing viscosity of the droplet facilitates the escalation by promoting the shearing effect under the same flow conditions. Ethylene glycol droplets primarily show the efficient coalescence even at a low Wee·Ca, which is attributed to the attraction of free charges induced by the increasing conductivity. In 1,6-hexanediol diacrylate/silicon oil emulsion, the droplet tends to form a liquid film that expands into the entire channel due to the affinity of the droplet to the channel wall. A variety of elongated columns are observed to oscillate between the electrodes at high voltages. These findings can contribute to understanding the electrohydrodynamic physics in o/o emulsion and controlling droplet behaviors in a fast response, programmable, and high-throughput way. We expect that this droplet manipulation technology can be widely adopted in a broad range of chemical synthesis and biological and material science.
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Affiliation(s)
- Weidong Fang
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing 100191, China
| | - Zhi Tao
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing 100191, China
| | - Haiwang Li
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing 100191, China
| | - Yuqian Ma
- University of California Irvine, Irvine 92697, California, United States
| | - Shuai Yin
- School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Tiantong Xu
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing 100191, China
| | - Teckneng Wong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University. 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Yi Huang
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing 100191, China
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2
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Zhang K, Xiang W, Liu J, Xie Z. Flexible droplet transportation and coalescence via controllable thermal fields. Anal Chim Acta 2023; 1277:341669. [PMID: 37604623 DOI: 10.1016/j.aca.2023.341669] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/03/2023] [Accepted: 07/26/2023] [Indexed: 08/23/2023]
Abstract
Flexible droplet transportation and coalescence are significant for lots of applications such as material synthesis and analytical detection. Herein, we present an effective method for controllable droplet transportation and coalescence via thermal fields. The device used for droplet manipulation is composed of a glass substrate with indium tin oxide-made microheaers and a microchannel with two transport branches and a central chamber, and it's manipulated by sequentially powering the microheaters located at the bottom of microchannel. The fluid will be unevenly heated when the microheater is actuated, leading to the formation of thermal buoyancy convection and the decrease of interfacial tension of fluids. Subsequently, the microdroplets can be transported from the inlets of microchannel to the target position by the buoyancy flow-induced Stokes drag. And the droplet migration velocity can be flexibly adjusted by changing the voltage applied on the microheater. After being transported to the center of central chamber, the coalescence behaviors of microdroplets can be triggered if the microheater located at the bottom of central chamber is continuously actuated. The droplet coalescence is the combined effect of decreased fluid interfacial tension, the shortened droplet distance by buoyancy flow and the increased instability of droplet under the elevated temperature. The droplet coalescence efficiency is also related to the voltage of microheater, by increasing the voltage from 3.5 V to 7 V, the needed time for droplet coalescence dramatically decrease from 220s to 1.4 s. Finally, by the droplet coalescence-triggered calcium hydroxide precipitation reaction, we demonstrate the applicability of the droplet manipulation method on specific sample detection. Therefore, this approach used for droplet transportation and coalescence can be attractive for many droplet-based applications such as analytical detection.
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Affiliation(s)
- Kailiang Zhang
- College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin, 150001, PR China
| | - Wei Xiang
- College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin, 150001, PR China
| | - Jiuqing Liu
- College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin, 150001, PR China
| | - Zhijie Xie
- College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin, 150001, PR China.
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3
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Raj M K, Priyadarshani J, Karan P, Bandyopadhyay S, Bhattacharya S, Chakraborty S. Bio-inspired microfluidics: A review. BIOMICROFLUIDICS 2023; 17:051503. [PMID: 37781135 PMCID: PMC10539033 DOI: 10.1063/5.0161809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/01/2023] [Indexed: 10/03/2023]
Abstract
Biomicrofluidics, a subdomain of microfluidics, has been inspired by several ideas from nature. However, while the basic inspiration for the same may be drawn from the living world, the translation of all relevant essential functionalities to an artificially engineered framework does not remain trivial. Here, we review the recent progress in bio-inspired microfluidic systems via harnessing the integration of experimental and simulation tools delving into the interface of engineering and biology. Development of "on-chip" technologies as well as their multifarious applications is subsequently discussed, accompanying the relevant advancements in materials and fabrication technology. Pointers toward new directions in research, including an amalgamated fusion of data-driven modeling (such as artificial intelligence and machine learning) and physics-based paradigm, to come up with a human physiological replica on a synthetic bio-chip with due accounting of personalized features, are suggested. These are likely to facilitate physiologically replicating disease modeling on an artificially engineered biochip as well as advance drug development and screening in an expedited route with the minimization of animal and human trials.
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Affiliation(s)
- Kiran Raj M
- Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
| | - Jyotsana Priyadarshani
- Department of Mechanical Engineering, Biomechanics Section (BMe), KU Leuven, Celestijnenlaan 300, 3001 Louvain, Belgium
| | - Pratyaksh Karan
- Géosciences Rennes Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, 35000 Rennes, France
| | - Saumyadwip Bandyopadhyay
- Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Soumya Bhattacharya
- Achira Labs Private Limited, 66b, 13th Cross Rd., Dollar Layout, 3–Phase, JP Nagar, Bangalore, Karnataka 560078, India
| | - Suman Chakraborty
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
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4
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Fang W, Tao Z, Li H, Yin S, Xu T, Huang Y, Wong T. AC-electric-field-controlled multi-component droplet coalescence at microscale. LAB ON A CHIP 2023; 23:2341-2355. [PMID: 37078784 DOI: 10.1039/d3lc00086a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Droplet coalescence with fast response, high controllability and monodispersity has been widely investigated in industrial production and bioengineering. Especially for droplets with multiple components, programmable manipulation of such droplets is crucial for practical applications. However, precise control of the dynamics can be challenging, owing to the complex boundaries and the interfacial and fluidic properties. AC electric fields, with their fast response and high flexibility, have attracted our interest. We design and fabricate an improved flow-focusing microchannel configuration together with a non-contact type of electrode featuring asymmetric geometries, based on which we conduct systematic investigations of the AC-electric-field-controlled coalescence of multi-component droplets at the microscale. Parameters such as flow rates, component ratio, surface tension, electric permittivity and conductivity were given our attention. The results show that droplet coalescence in different flow parameters can be achieved in milliseconds by adjusting the electrical conditions, which shows high controllability. Specifically, both the coalescence region and reaction time can be adjusted by a combination of applied voltage and frequency, and unique merging phenomena have appeared. One is contact coalescence with the approach of paired droplets, while the other is squeezing coalescence, which occurs in the start position and promotes the merging process. The fluid properties, such as the electric permittivity, conductivity and surface tension, present a significant influence on merging behavior. The increasing relative dielectric constant leads to a dramatic reduction of the start merging voltage from the original 250 V to 30 V. The range of effective voltage for coalescence decreases with the addition of surfactant, offering a stricter and yet higher selectivity on electrical conditions, about 1500 V. The conductivity presents a negative correlation with the start merging voltage due to the reduction of the dielectric stress, from 400 V to 1500 V. Finally, we achieve the precise fabrication process of the Janus droplet via implementation of the proposed method, where the components of the droplets and the coalescence conditions are well controlled. Our results can serve as a potent methodology to decipher the physics of multi-component droplet electro-coalescence and contribute to applications in chemical synthesis, bioassay and material synthesis.
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Affiliation(s)
- Weidong Fang
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing, 100191, China.
| | - Zhi Tao
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing, 100191, China.
| | - Haiwang Li
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing, 100191, China.
| | - Shuai Yin
- School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Tiantong Xu
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing, 100191, China.
| | - Yi Huang
- National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Research Institute of Aero-Engine, Beihang University, Beijing, 100191, China.
| | - Teckneng Wong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
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5
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Hu Q, Hu F, Xu D, Zhang K. Numerical Analysis of Droplet Impacting on an Immiscible Liquid via Three-Phase Field Method. MICROMACHINES 2023; 14:mi14050951. [PMID: 37241573 DOI: 10.3390/mi14050951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/15/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023]
Abstract
In this work, we establish a two-dimensional axisymmetric simulation model to numerically study the impacting behaviors between oil droplets and an immiscible aqueous solution based on the three-phase field method. The numerical model is established by using the commercial software of COMSOL Multiphysics first and then validated by comparing the numerical results with the previous experimental study. The simulation results show that under the impact of oil droplets, a crater will form on the surface of the aqueous solution, which firstly expands and then collapses with the transfer and dissipation of kinetic energy of this three-phase system. As for the droplet, it flattens, spreads, stretches, or immerses on the crater surface and finally achieves an equilibrium state at the gas-liquid interface after experiencing several sinking-bouncing circles. The impacting velocity, fluid density, viscosity, interfacial tension, droplet size, and the property of non-Newtonian fluids all play important roles in the impact between oil droplets and aqueous solution. The conclusions can help to cognize the mechanism of droplet impact on an immiscible fluid and provide useful guidelines for those applications concerning droplet impact.
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Affiliation(s)
- Qingming Hu
- School of Mechtranoics Engineering, Qiqihar University, Qiqihaer 161006, China
- The Engineering Technology Research Center for Precision Manufacturing Equipment and Industrial Perception of Heilongjiang Province, Qiqihar University, Qiqihaer 161006, China
- The Collaborative Innovation Center for Intelligent Manufacturing Equipment Industrialization, Qiqihar University, Qiqihaer 161006, China
| | - Fengshi Hu
- School of Mechtranoics Engineering, Qiqihar University, Qiqihaer 161006, China
| | - Donghui Xu
- School of Mechtranoics Engineering, Qiqihar University, Qiqihaer 161006, China
| | - Kailiang Zhang
- College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin 150040, China
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6
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Li H, Zhang Y, Gu XS, Qi H, Yu J, Zhuang J. Study on the shear stress and interfacial friction of droplets moving on a superhydrophobic surface. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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7
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Yin S, Huang Y, Li H, Wong TN. Dynamics of alternating current electric field–assisted non‐Newtonian droplet formation with geometry confinement. Electrophoresis 2022; 43:2120-2129. [DOI: 10.1002/elps.202200056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 04/06/2022] [Accepted: 04/22/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Shuai Yin
- School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore
| | - Yi Huang
- School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore
- Research Institute of Aero‐Engine Beihang University Beijing P. R. China
| | - Haiwang Li
- Research Institute of Aero‐Engine Beihang University Beijing P. R. China
| | - Teck Neng Wong
- School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore
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8
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Amirifar L, Besanjideh M, Nasiri R, Shamloo A, Nasrollahi F, de Barros NR, Davoodi E, Erdem A, Mahmoodi M, Hosseini V, Montazerian H, Jahangiry J, Darabi MA, Haghniaz R, Dokmeci MR, Annabi N, Ahadian S, Khademhosseini A. Droplet-based microfluidics in biomedical applications. Biofabrication 2021; 14. [PMID: 34781274 DOI: 10.1088/1758-5090/ac39a9] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 11/15/2021] [Indexed: 11/11/2022]
Abstract
Droplet-based microfluidic systems have been employed to manipulate discrete fluid volumes with immiscible phases. Creating the fluid droplets at microscale has led to a paradigm shift in mixing, sorting, encapsulation, sensing, and designing high throughput devices for biomedical applications. Droplet microfluidics has opened many opportunities in microparticle synthesis, molecular detection, diagnostics, drug delivery, and cell biology. In the present review, we first introduce standard methods for droplet generation (i.e., passive and active methods) and discuss the latest examples of emulsification and particle synthesis approaches enabled by microfluidic platforms. Then, the applications of droplet-based microfluidics in different biomedical applications are detailed. Finally, a general overview of the latest trends along with the perspectives and future potentials in the field are provided.
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Affiliation(s)
- Leyla Amirifar
- Mechanical Engineering, Sharif University of Technology, Tehran, Iran, Tehran, 11365-11155, Iran (the Islamic Republic of)
| | - Mohsen Besanjideh
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Tehran, 11365-11155, Iran (the Islamic Republic of)
| | - Rohollah Nasiri
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Tehran, 11365-11155, Iran (the Islamic Republic of)
| | - Amir Shamloo
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Tehran, 11365-11155, Iran (the Islamic Republic of)
| | | | - Natan Roberto de Barros
- Terasaki Institute for Biomedical Innovation (TIBI), Los Angeles, Los Angeles, 90024, UNITED STATES
| | - Elham Davoodi
- Bioengineering, University of California - Los Angeles, Los Angeles, Los Angeles, 90095, UNITED STATES
| | - Ahmet Erdem
- Bioengineering, University of California - Los Angeles, Los Angeles, Los Angeles, 90095, UNITED STATES
| | | | - Vahid Hosseini
- Terasaki Institute for Biomedical Innovation (TIBI), Los Angeles, Los Angeles, 90024, UNITED STATES
| | - Hossein Montazerian
- Bioengineering, University of California - Los Angeles, Los Angeles, Los Angeles, 90095, UNITED STATES
| | - Jamileh Jahangiry
- University of California - Los Angeles, Los Angeles, Los Angeles, 90095, UNITED STATES
| | | | - Reihaneh Haghniaz
- Terasaki Institute for Biomedical Innovation (TIBI), Los Angeles, Los Angeles, 90024, UNITED STATES
| | - Mehmet R Dokmeci
- Terasaki Institute for Biomedical Innovation (TIBI), Los Angeles, Los Angeles, 90024, UNITED STATES
| | - Nasim Annabi
- Chemical Engineering, UCLA, Los Angeles, Los Angeles, California, 90095, UNITED STATES
| | - Samad Ahadian
- Terasaki Institute for Biomedical Innovation (TIBI), Los Angeles, Los Angeles, 90024, UNITED STATES
| | - Ali Khademhosseini
- Terasaki Institute for Biomedical Innovation (TIBI), Los Angeles, Los Angeles, 90024, UNITED STATES
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9
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Yin S, Huang Y, Wong TN. Critical conditions for organic thread cutting under electric fields. SOFT MATTER 2021; 17:2913-2919. [PMID: 33587082 DOI: 10.1039/d0sm02078h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Conditions for triggering the cutting of organic samples under an AC electric field are investigated in a microchannel to explore the strategy for organic sample manipulation. Based on the nature of triggering and developing instability at liquid interfaces, in combination with an equivalent electric circuit model, a novel electric capillary number method is proposed as a comprehensive critical condition for the cutting. We uncover the physics behind cutting and non-cutting of an organic thread for different electric frequencies, electric properties of fluid, and width of the organic thread. The critical time required and the critical cutting position are studied to offer guidelines for accurate cutting. Higher electric frequency and higher permittivity of the aqueous phase surrounding the organic phase can reduce the voltage required for cutting. In summary, the newly defined electric capillary number is proved to be a comprehensive criterion for determining the cutting phenomena, which is capable of considering the interfacial tension, the electric permittivity and the electric field strength applied. The results offer applicable references for achieving efficient and accurate cutting of organic samples in practical applications.
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Affiliation(s)
- Shuai Yin
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
| | - Yi Huang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. and Research Institute of Aero-Engine, Beihang University, No. 37 XueYuan Road, Haidian District, Beijing, 100083, China
| | - Teck Neng Wong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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10
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Yao X, Marcos. Interaction between two spheres under a uniform electric field in a porous medium. Chem Eng Sci 2021. [DOI: 10.1016/j.ces.2020.116254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Zhu J, Tang R, Chen Y, Yin S, Huang Y, Wong T. Investigation of Shear-Driven and Pressure-Driven Liquid Crystal Flow at Microscale: A Quantitative Approach for the Flow Measurement. MICROMACHINES 2020; 12:28. [PMID: 33383897 PMCID: PMC7823904 DOI: 10.3390/mi12010028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/09/2020] [Accepted: 12/23/2020] [Indexed: 11/30/2022]
Abstract
The liquid crystal-based method is a new technology developed for flow visualizations and measurements at microscale with great potentials. It is the priority to study the flow characteristics before implementation of such a technology. A numerical analysis has been applied to solve the simplified dimensionless two-dimensional Leslie-Ericksen liquid crystal dynamic equation. This allows us to analyze the coupling effect of the LC's director orientation and flow field. We will be discussing two classic shear flow cases at microscale, namely Couette and Poiseuille flow. In both cases, the plate drag speed in the state of Couette flow are varied as well as the pressure gradients in Poiseuille flow state are changed to study their effects on the flow field distributions. In Poiseuille flow, with the increase of applied pressure gradient, the influence of backflow significantly affects the flow field. Results show that the proposed method has great advantages on measurement near the wall boundaries which could complement to the current adopted flow measurement technique. The mathematical model proposed in this article could be of great potentials in the development of the quantitatively flow measurement technology.
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Affiliation(s)
- Jianqin Zhu
- National Key Laboratory of Science and Technology on Aero-Thermodynamics, School of Energy and Power Engineering, Beihang University, Beijing 100083, China; (J.Z.); (R.T.); (Y.C.)
| | - Runze Tang
- National Key Laboratory of Science and Technology on Aero-Thermodynamics, School of Energy and Power Engineering, Beihang University, Beijing 100083, China; (J.Z.); (R.T.); (Y.C.)
| | - Yu Chen
- National Key Laboratory of Science and Technology on Aero-Thermodynamics, School of Energy and Power Engineering, Beihang University, Beijing 100083, China; (J.Z.); (R.T.); (Y.C.)
| | - Shuai Yin
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Singapore 639798, Singapore;
| | - Yi Huang
- Research Institute of Aero-Engine, Beihang University, Beijing 100083, China
| | - Teckneng Wong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Singapore 639798, Singapore;
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12
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Sattari A, Hanafizadeh P, Hoorfar M. Multiphase flow in microfluidics: From droplets and bubbles to the encapsulated structures. Adv Colloid Interface Sci 2020; 282:102208. [PMID: 32721624 DOI: 10.1016/j.cis.2020.102208] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/19/2020] [Accepted: 07/04/2020] [Indexed: 12/14/2022]
Abstract
Microfluidic technologies have a unique ability to control more precisely and effectively on two-phase flow systems in comparison with macro systems. Controlling the size of the droplets and bubbles has led to an ever-increasing expansion of this technology in two-phase systems. Liquid-liquid and gas-liquid two-phase flows because of their numerous applications in different branches such as reactions, synthesis, emulsions, cosmetic, food, drug delivery, etc. have been the most critical two-phase flows in microfluidic systems. This review highlights recent progress in two-phase flows in microfluidic devices. The fundamentals of two-phase flows, including some essential dimensionless numbers, governing equations, and some most well-known numerical methods are firstly introduced, followed by a review of standard methods for producing segmented flows such as emulsions in microfluidic systems. Then various encapsulated structures, a common two-phase flow structure in microfluidic devices, and different methods of their production are reviewed. Finally, applications of two-phase microfluidic flows in drug-delivery, biotechnology, mixing, and microreactors are briefly discussed.
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13
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Liang D, Ma P, Zhu C, Fu T, Ma Y, Wang K, Luo G. Manipulable Formation of Ferrofluid Droplets in Y-Shaped Flow-Focusing Microchannels. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b02516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Di Liang
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Pengcheng Ma
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Chunying Zhu
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Taotao Fu
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Youguang Ma
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Kai Wang
- State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Guangsheng Luo
- State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
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14
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Huang Y, Yin S, Chong WH, Wong TN, Ooi KT. Precise morphology control and fast merging of a complex multi-emulsion system: the effects of AC electric fields. SOFT MATTER 2019; 15:5614-5625. [PMID: 31166359 DOI: 10.1039/c9sm00430k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We showed that an AC electric field can be effectively used to control the full morphology of a multi-emulsion system (oil/water/oil, O/W/O and water/oil/water, W/O/W); specifically, the size of outer droplets and the number of inner droplets (from 5 to 0) could be controlled. In our system, such control was achieved by adopting non-contact type of electrodes together with double-flow-focusing geometry to apply an AC electric field during the formation of complex droplets. As such, the AC electric field could be used without contamination. In addition to morphology control, we also achieved both one-step and two-step merging of the core droplets in the W/O/W droplet system within 100 milliseconds, which is by far the fastest merging in double emulsion droplets ever reported. To the best of our knowledge, this paper is the first article to report the control of core droplets in an O/W/O system by matching the frequency of the AC electric field with that of the core production rate. In this article, we adopted the electric capillary number CaE to analyze the effectiveness of the AC electric field applied at a high frequency, which offers a guideline for practical applications. Furthermore, the merging phenomena among various droplet systems discovered could add extra dimensions for the manipulation of double emulsions. Our findings reveal new physical insights that bring about a better understanding of the interfacial phenomena and electrohydrodynamics of droplets, which is of great importance for practical applications involving the complex interactions of multiple droplets.
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Affiliation(s)
- Yi Huang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Avenue, 639798, Singapore.
| | - Shuai Yin
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Avenue, 639798, Singapore.
| | - Wen Han Chong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Avenue, 639798, Singapore.
| | - Teck Neng Wong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Avenue, 639798, Singapore.
| | - Kim Tiow Ooi
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang, Avenue, 639798, Singapore.
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Xiao L, Sun H. Novel properties and applications of carbon nanodots. NANOSCALE HORIZONS 2018; 3:565-597. [PMID: 32254112 DOI: 10.1039/c8nh00106e] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In the most recent decade, carbon dots have drawn intensive attention and triggered substantial investigation. Carbon dots manifest superior merits, including excellent biocompatibility both in vitro and in vivo, resistance to photobleaching, easy surface functionalization and bio-conjugation, outstanding colloidal stability, eco-friendly synthesis, and low cost. All of these endow them with the great potential to replace conventional unsatisfactory fluorescent heavy metal-containing semiconductor quantum dots or organic dyes. Even though the understanding of their photoluminescence mechanism is still controversial, carbon dots have already exhibited many versatile applications. In this article, we summarize and review the recent progress achieved in the field of carbon dots, and provide a comprehensive summary and discussion on their synthesis methods and emission mechanisms. We also present the applications of carbon dots in bioimaging, drug delivery, microfluidics, light emitting diode (LED), sensing, logic gates, and chiral photonics, etc. Some unaddressed issues, challenges, and future prospects of carbon dots are also discussed. We envision that carbon dots will eventually have great commercial utilization and will become a strong competitor to some currently used fluorescent materials. It is our hope that this review will provide insights into both the fundamental research and practical applications of carbon dots.
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Affiliation(s)
- Lian Xiao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
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