1
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Nan L, Mao T, Shum HC. Self-synchronization of reinjected droplets for high-efficiency droplet pairing and merging. MICROSYSTEMS & NANOENGINEERING 2023; 9:24. [PMID: 36910256 PMCID: PMC9995457 DOI: 10.1038/s41378-023-00502-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/10/2023] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
Droplet merging serves as a powerful tool to add reagents to moving droplets for biological and chemical reactions. However, unsynchronized droplet pairing impedes high-efficiency merging. Here, we develop a microfluidic design for the self-synchronization of reinjected droplets. A periodic increase in the hydrodynamic resistance caused by droplet blocking a T-junction enables automatic pairing of droplets. After inducing spacing, the paired droplets merge downstream under an electric field. The blockage-based design can achieve a 100% synchronization efficiency even when the mismatch rate of droplet frequencies reaches 10%. Over 98% of the droplets can still be synchronized at nonuniform droplet sizes and fluctuating reinjection flow rates. Moreover, the droplet pairing ratio can be adjusted flexibly for on-demand sample addition. Using this system, we merge two groups of droplets encapsulating enzyme/substrate, demonstrating its capacity to conduct multi-step reactions. We also combine droplet sorting and merging to coencapsulate single cells and single beads, providing a basis for high-efficiency single-cell sequencing. We expect that this system can be integrated with other droplet manipulation systems for a broad range of chemical and biological applications.
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Affiliation(s)
- Lang Nan
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong China
| | - Tianjiao Mao
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ho Cheung Shum
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong China
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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2
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Agnihotri SN, Ugolini GS, Sullivan MR, Yang Y, De Ganzó A, Lim JW, Konry T. Droplet microfluidics for functional temporal analysis and cell recovery on demand using microvalves: application in immunotherapies for cancer. LAB ON A CHIP 2022; 22:3258-3267. [PMID: 35904070 PMCID: PMC9535857 DOI: 10.1039/d2lc00435f] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Most common methods of cellular analysis employ the top-down approach (investigating proteomics or genomics directly), thereby destroying the cell, which does not allow the possibility of using the same cell to correlate genomics with functional assays. Herein we describe an approach for single-cell tools that serve as a bottom-up approach. Our technology allows functional phenotyping to be conducted by observing the cytotoxicity of cells and then probe the underlying biology. We have developed a droplet microfluidic device capable of trapping droplets in the array and releasing the droplet of interest selectively using microvalves. Each droplet in the array encapsulates natural killer cells (NK cells) and tumour cells for real-time monitoring of burst kinetics and spatial coordination during killing by single NK cells. Finally, we use the microvalve actuation to selectively release droplets with the desired functional phenotype such as for fast and serial killing of target tumour cells by NK cells. From this perspective, our device allows for investigating first interactions and real-time monitoring of kinetics and later cell recovery on demand for single-cell omic analysis such as single-cell RNA sequencing (scRNA), which to date, is primarily based on in-depth analyses of the entire transcriptome of a relatively low number of cells.
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Affiliation(s)
- Sagar N Agnihotri
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
| | - Giovanni Stefano Ugolini
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
| | - Matthew Ryan Sullivan
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
| | - Yichao Yang
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
| | - Agustin De Ganzó
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
| | - Ji Won Lim
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
| | - Tania Konry
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
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3
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Hu J, Cochrane WG, Jones AX, Blackmond DG, Paegel BM. Chiral lipid bilayers are enantioselectively permeable. Nat Chem 2021; 13:786-791. [PMID: 34112989 PMCID: PMC8325640 DOI: 10.1038/s41557-021-00708-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 04/16/2021] [Indexed: 12/17/2022]
Abstract
Homochiral membrane bilayers organize biological functions in all domains of life. The membrane’s permeability–its key property–correlates with a molecule’s lipophilicity, but the role of the membrane’s rich and uniform stereochemistry as a permeability determinant is largely ignored in empirical and computational measurements. Here, we describe a new approach to measuring permeation using continuously generated microfluidic droplet interface bilayers (DIBs, 480/min) and benchmark this system by monitoring fluorescent dye DIB permeation over time. Permeation of non-fluorescent, alkyne-labeled molecules was measured using a fluorogenic click reaction. DIB transport measurements revealed enantioselective permeation of alkyne-labeled amino acids (Ala, Val, Phe, Pro) and dipeptides through a chiral phospholipid bilayer; the biological L enantiomers permeated faster than D (1.2–6-fold; Ala–Pro). Enantioselective permeation both poses a potentially unanticipated criterion for drug design and offers a kinetic mechanism for the abiotic emergence of homochirality via chiral transfer between sugars, amino acids, and lipids.
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Affiliation(s)
- Juan Hu
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Wesley G Cochrane
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | | | | | - Brian M Paegel
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA. .,Departments of Chemistry and Biomedical Engineering, University of California, Irvine, CA, USA.
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4
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Ghorbani Kharaji Z, Bayareh M, Kalantar V. A review on acoustic field-driven micromixers. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING 2021. [DOI: 10.1515/ijcre-2020-0188] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
A review on acoustic field-driven micromixers is given. This is supplemented by the governing equations, governing non-dimensional parameters, numerical simulation approaches, and fabrication techniques. Acoustically induced vibration is a kind of external energy input employed in active micromixers to improve the mixing performance. An air bubble energized by an acoustic field acts as an external energy source and induces friction forces at the interface between an air bubble and liquid, leading to the formation of circulatory flows. The current review (with 200 references) evaluates different characteristics of microfluidic devices working based on acoustic field shaking.
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Affiliation(s)
| | - Morteza Bayareh
- Department of Mechanical Engineering , Shahrekord University , Shahrekord , Iran
| | - Vali Kalantar
- Department of Mechanical Engineering , Yazd University , Yazd , Iran
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5
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Zhang R, Gao C, Tian L, Wang R, Hong J, Gao M, Gui L. Dynamic pneumatic rails enabled microdroplet manipulation. LAB ON A CHIP 2021; 21:105-112. [PMID: 33295911 DOI: 10.1039/d0lc00805b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This study presented a convenient method of gathering, splitting, merging, and sorting microdroplets by dynamic pneumatic rails in double-layered microfluidic devices. In these devices, the pneumatic rails were placed below the droplet channel, with a thin elastic polydimethylsiloxane (PDMS) film between them. The PDMS film would sag down to the rail channel, forming a groove pattern at the bottom of the droplet channel, when the fluid pressure in the droplet channel was higher than the air pressure in the rail channel. The groove could capture the flattened droplets and guide the flow path of them due to the lowered surface energy when they extended into the groove. We have designed different components consisting of pneumatic rails to split, merge and sort droplets, and demonstrated that the components maintained good performance in manipulating droplets only by controlling the air pressure. Furthermore, a pneumatic rail-based sorter has been successfully used to sort out single-cell droplets. The pneumatic rail can be integrated into pneumatic valve-based microfluidic devices to be a flexible tool for droplet-based biological and chemical analysis.
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Affiliation(s)
- Renchang Zhang
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 29 Zhongguancun East Road, Haidu District, Beijing 10019, China.
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6
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Microfluidic Chamber Design for Controlled Droplet Expansion and Coalescence. MICROMACHINES 2020; 11:mi11040394. [PMID: 32290165 PMCID: PMC7231328 DOI: 10.3390/mi11040394] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/07/2020] [Accepted: 04/07/2020] [Indexed: 11/21/2022]
Abstract
The defined formation and expansion of droplets are essential operations for droplet-based screening assays. The volumetric expansion of droplets causes a dilution of the ingredients. Dilution is required for the generation of concentration graduation which is mandatory for many different assay protocols. Here, we describe the design of a microfluidic operation unit based on a bypassed chamber and its operation modes. The different operation modes enable the defined formation of sub-µL droplets on the one hand and the expansion of low nL to sub-µL droplets by controlled coalescence on the other. In this way the chamber acts as fluidic interface between two fluidic network parts dimensioned for different droplet volumes. Hence, channel confined droplets of about 30–40 nL from the first network part were expanded to cannel confined droplets of about 500 to about 2500 nL in the second network part. Four different operation modes were realized: (a) flow rate independent droplet formation in a self-controlled way caused by the bypassed chamber design, (b) single droplet expansion mode, (c) multiple droplet expansion mode, and (d) multiple droplet coalescence mode. The last mode was used for the automated coalescence of 12 droplets of about 40 nL volume to produce a highly ordered output sequence with individual droplet volumes of about 500 nL volume. The experimental investigation confirmed a high tolerance of the developed chamber against the variation of key parameters of the dispersed-phase like salt content, pH value and fluid viscosity. The presented fluidic chamber provides a solution for the problem of bridging different droplet volumes in a fluidic network.
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7
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Chen Y, Yang J, Wu J, Li Z, Liu S, Zhong H, Zhou R, Luo A, Ho HP, He S, Xing X, Shui L. Generation and manipulation of oil-in-water micro-droplets by confined thermocapillary microvortices. OPTICS LETTERS 2020; 45:1998-2001. [PMID: 32236052 DOI: 10.1364/ol.388188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/26/2020] [Indexed: 06/11/2023]
Abstract
Optofluidic manipulation of droplets is critical in droplet-based microfluidic systems for chemistry, biology, and medicine. Here, we reported a thermocapillary microvortices-based manipulation platform for controlling oil-in-water droplets through integrating a photothermal waveguide into a microfluidic chip. The sizes and shapes of the droplets can be controlled by adjusting optical power or positions of the water-oil interface. Here, teardrop-shaped droplets, which can encapsulate and accumulate mesoscopic matters easily, were generated when the water-oil interface and the channel boundaries approached the photothermal waveguide center simultaneously. The results showed that the thermocapillary microvortices have good controllability of droplet positions, droplet volumes, and encapsulated-particle distribution and thus it will be a powerful droplet manipulation strategy for microreactors and microcapsules.
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8
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Rehman AU, Coskun UC, Rashid Z, Morova B, Jonáš A, Erten A, Kiraz A. Size-Based Sorting of Emulsion Droplets in Microfluidic Channels Patterned with Laser-Ablated Guiding Tracks. Anal Chem 2020; 92:2597-2604. [PMID: 31905281 DOI: 10.1021/acs.analchem.9b04308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate an autonomous, high-throughput mechanism for sorting of emulsion droplets with different sizes concurrently flowing in a microfluidic Hele-Shaw channel. The aqueous droplets of varying radii suspended in olive oil are separated into different streamlines across the channel upon interaction with a shallow (depth ∼ 700 nm) inclined guiding track ablated into the polydimethylsiloxane-coated surface of the channel with focused femtosecond laser pulses. Specifically, the observed differences in the droplet trajectories along the guiding track arise due to the different scaling of the confinement force attracting the droplets into the track, fluid drag, and wall friction, with the droplet radius. In addition, the distance traveled by the droplets along the track also depends on the track width, with wider tracks providing more stable droplet guiding for any given droplet size. We systematically study the influence of the droplet size and velocity on the trajectory of the droplets in the channel and analyze the sensitivity of size-based droplet sorting for varying flow conditions. The droplet guiding and sorting experiments are complemented by modeling of the droplet motion in the channel flow using computational fluid dynamics simulations and a previously developed model of droplet guiding. Finally, we demonstrate a complete separation of droplets produced by fusion of two independent droplet streams at the inlet of the Hele-Shaw channel from unfused daughter droplets. The presented droplet sorting technique can find applications in the development of analytical and preparative microfluidic protocols.
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Affiliation(s)
| | - Umut C Coskun
- Department of Mechanical Engineering , Istanbul Technical University , 34437 Gumussuyu , Istanbul , Turkey
| | - Zeeshan Rashid
- Department of Electrical Engineering , The Islamia University of Bahawalpur , 63100 , Bahawalpur , Pakistan
| | | | - Alexandr Jonáš
- Czech Academy of Sciences, Institute of Scientific Instruments , Královopolská 147 , 61264 Brno , Czech Republic
| | - Ahmet Erten
- Department of Electronics and Communication Engineering , Istanbul Technical University , 34469 Maslak , Istanbul , Turkey
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9
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Zhang Y, Bracken H, Woolhead C, Zagnoni M. Functionalisation of human chloride intracellular ion channels in microfluidic droplet-interface-bilayers. Biosens Bioelectron 2019; 150:111920. [PMID: 31791876 DOI: 10.1016/j.bios.2019.111920] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/12/2019] [Accepted: 11/23/2019] [Indexed: 01/06/2023]
Abstract
Profiling ion flux through human intracellular chloride ion channels using live-cell based techniques, such as patch-clamp electrophysiology, is laborious and time-consuming. The integration of scalable microfluidic systems with automatable protocols based on droplet-interface-bilayers (DIBs) within which ion channels are incorporated circumvents several limitations associated with live-cell measurements and facilitates testing in controllable in vitro conditions. Here, we have designed and tested novel microfluidic layouts for the formation of arrays of DIBs in parallel and developed the first example of a miniaturised, DIB-based, fluorescence assays for Cl- fluxing, allowing the investigation of the functional properties of the human chloride intracellular ion channel 1 (CLIC1). The microfluidic protocols relied on passive geometries for droplet pairing and DIB formation. Using recombinantly expressed CLIC1, we identified the best conditions to maximise protein integration into a lipid bilayer and the oligomerisation of the protein into functional ion channels. Finally, CLIC1 ion channel functionality was assessed relative to α-Haemolysin into microfluidic DIBs using the same Cl- fluxing assay.
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Affiliation(s)
- Yu Zhang
- Centre for Microsystems and Photonics, EEE Dept., University of Strathclyde, Glasgow, UK
| | - Hazel Bracken
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Cheryl Woolhead
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Michele Zagnoni
- Centre for Microsystems and Photonics, EEE Dept., University of Strathclyde, Glasgow, UK.
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10
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Ferraro D, Serra M, Filippi D, Zago L, Guglielmin E, Pierno M, Descroix S, Viovy JL, Mistura G. Controlling the distance of highly confined droplets in a capillary by interfacial tension for merging on-demand. LAB ON A CHIP 2018; 19:136-146. [PMID: 30484796 DOI: 10.1039/c8lc01182f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Droplet microfluidics is a powerful technology that finds many applications in chemistry and biomedicine. Among different configurations, droplets confined in a capillary (or plugs) present a number of advantages: they allow positional identification and simplify the integration of complex multi-steps protocols. However, these protocols rely on the control of droplet speed, which is affected by a complex and still debated interplay of various physico-chemical parameters like droplet length, viscosity ratio between droplets and carrier fluid, flow rate and interfacial tension. We present here a systematic investigation of the droplet speed as a function of their length and interfacial tension, and propose a novel, simple and robust methodology to control the relative distance between consecutive droplets flowing in microfluidic channels through the addition of surfactants either into the dispersed and/or into the continuous phases. As a proof of concept application, we present the possibility to accurately trigger in space and time the merging of two confined droplets flowing in a uniform cross-section circular capillary. This approach is further validated by monitoring a conventional enzymatic reaction used to quantify the concentration of H2O2 in a biological sample, showing its potentialities in both continuous and stopped assay methods.
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Affiliation(s)
- D Ferraro
- Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, via Marzolo 8, 35131 Padova, Italy.
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11
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Yoon DH, Tanaka D, Sekiguchi T, Shoji S. Size-Dependent and Property-Independent Passive Microdroplet Sorting by Droplet Transfer on Dot Rails. MICROMACHINES 2018; 9:E513. [PMID: 30424446 PMCID: PMC6215178 DOI: 10.3390/mi9100513] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 11/16/2022]
Abstract
A fully passive microdroplet sorting method is presented in this paper. On the rails with dot patterns, the droplets were sorted in different ways depending on their size. However, the effect of droplet properties on the threshold size of the sorting was eliminated. The droplet positions on two railways and the Laplace pressure of the droplets on the dot patterns allowed selective droplet transfer according to size. Different gaps between the rails altered the threshold size of the transfer. However, the threshold size was independent of the droplet's surface tension and viscosity because the droplet transfer utilized only the droplet position and Laplace pressure without lateral flow to sort targets. This feature has a high potential for bio/chemical applications requiring categorization of droplet targets consisting of various mixtures as pre- or post-elements.
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Affiliation(s)
- Dong Hyun Yoon
- Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
| | - Daiki Tanaka
- Research Organization for Nano & Life Innovation, Waseda University, 513, Tsurumaki-cho, Waseda, Shinjuku-ku, Tokyo 162-0041, Japan.
| | - Tetsushi Sekiguchi
- Research Organization for Nano & Life Innovation, Waseda University, 513, Tsurumaki-cho, Waseda, Shinjuku-ku, Tokyo 162-0041, Japan.
| | - Shuichi Shoji
- Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
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12
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Ma R, Zhang Q, Fu T, Zhu C, Wang K, Ma Y, Luo G. Manipulation of microdroplets at a T-junction: Coalescence and scaling law. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2018.04.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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13
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Cheng WL, Sadr R, Dai J, Han A. Prediction of Microdroplet Breakup Regime in Asymmetric T-Junction Microchannels. Biomed Microdevices 2018; 20:72. [DOI: 10.1007/s10544-018-0310-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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14
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Orbay S, Ozcelik A, Bachman H, Huang TJ. Acoustic Actuation of in situ Fabricated Artificial Cilia. JOURNAL OF MICROMECHANICS AND MICROENGINEERING : STRUCTURES, DEVICES, AND SYSTEMS 2018; 28:025012. [PMID: 30479458 PMCID: PMC6251322 DOI: 10.1088/1361-6439/aaa0ae] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We present on-chip acoustic actuation of in situ fabricated artificial cilia. Arrays of cilia structures are UV polymerized inside a microfluidic channel using a photocurable polyethylene glycol (PEG) polymer solution and photomasks. During polymerization, cilia structures are attached to a silane treated glass surface inside the microchannel. Then, the cilia structures are actuated using acoustic vibrations at 4.6 kHz generated by piezo transducers. As a demonstration of a practical application, DI water and fluorescein dye solutions are mixed inside a microfluidic channel. Using pulses of acoustic excitations, and locally fabricated cilia structures within a certain region of the microchannel, a waveform of mixing behavior is obtained. This result illustrates one potential application wherein researchers can achieve spatiotemporal control of biological microenvironments in cell stimulation studies. These acoustically actuated, in situ fabricated, cilia structures can be used in many on-chip applications in biological, chemical and engineering studies.
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Affiliation(s)
- Sinem Orbay
- Institute of Biomedical Engineering, Bogazici University, Cengelkoy, Istanbul, 34684, Turkey
| | - Adem Ozcelik
- Department of Electronics and Automation, Soma Vocational School, Manisa Celal Bayar University, Soma, Manisa, 45500, Turkey
| | - Hunter Bachman
- Department of Mechanical Engineering and Material Science, Duke University, Durham, NC, 27708, USA
| | - Tony Jun Huang
- Department of Mechanical Engineering and Material Science, Duke University, Durham, NC, 27708, USA
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15
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Cochrane WG, Hackler AL, Cavett VJ, Price AK, Paegel BM. Integrated, Continuous Emulsion Creamer. Anal Chem 2017; 89:13227-13234. [PMID: 29124927 DOI: 10.1021/acs.analchem.7b03070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Automated and reproducible sample handling is a key requirement for high-throughput compound screening and currently demands heavy reliance on expensive robotics in screening centers. Integrated droplet microfluidic screening processors are poised to replace robotic automation by miniaturizing biochemical reactions to the droplet scale. These processors must generate, incubate, and sort droplets for continuous droplet screening, passively handling millions of droplets with complete uniformity, especially during the key step of sample incubation. Here, we disclose an integrated microfluidic emulsion creamer that packs ("creams") assay droplets by draining away excess oil through microfabricated drain channels. The drained oil coflows with creamed emulsion and then reintroduces the oil to disperse the droplets at the circuit terminus for analysis. Creamed emulsion assay incubation time dispersion was 1.7%, 3-fold less than other reported incubators. The integrated, continuous emulsion creamer (ICEcreamer) was used to miniaturize and optimize measurements of various enzymatic activities (phosphodiesterase, kinase, bacterial translation) under multiple- and single-turnover conditions. Combining the ICEcreamer with current integrated microfluidic DNA-encoded library bead processors eliminates potentially cumbersome instrumentation engineering challenges and is compatible with assays of diverse target class activities commonly investigated in drug discovery.
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Affiliation(s)
- Wesley G Cochrane
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Amber L Hackler
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Valerie J Cavett
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Alexander K Price
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Brian M Paegel
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
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16
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Han SI, Soo Kim H, Han A. In-droplet cell concentration using dielectrophoresis. Biosens Bioelectron 2017; 97:41-45. [DOI: 10.1016/j.bios.2017.05.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 04/28/2017] [Accepted: 05/18/2017] [Indexed: 10/19/2022]
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17
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Cai G, Xue L, Zhang H, Lin J. A Review on Micromixers. MICROMACHINES 2017; 8:E274. [PMID: 30400464 PMCID: PMC6189760 DOI: 10.3390/mi8090274] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/30/2017] [Accepted: 09/01/2017] [Indexed: 01/23/2023]
Abstract
Microfluidic devices have attracted increasing attention in the fields of biomedical diagnostics, food safety control, environmental protection, and animal epidemic prevention. Micromixing has a considerable impact on the efficiency and sensitivity of microfluidic devices. This work reviews recent advances on the passive and active micromixers for the development of various microfluidic chips. Recently reported active micromixers driven by pressure fields, electrical fields, sound fields, magnetic fields, and thermal fields, etc. and passive micromixers, which owned two-dimensional obstacles, unbalanced collisions, spiral and convergence-divergence structures or three-dimensional lamination and spiral structures, were summarized and discussed. The future trends for micromixers to combine with 3D printing and paper channel were brought forth as well.
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Affiliation(s)
- Gaozhe Cai
- Key Laboratory of Agricultural Information Acquisition Technology (Beijing) of Ministry of Agriculture, China Agricultural University, 17 East Qinghua Road, Beijing 100083, China.
| | - Li Xue
- Key Laboratory of Agricultural Information Acquisition Technology (Beijing) of Ministry of Agriculture, China Agricultural University, 17 East Qinghua Road, Beijing 100083, China.
| | - Huilin Zhang
- Key Laboratory of Agricultural Information Acquisition Technology (Beijing) of Ministry of Agriculture, China Agricultural University, 17 East Qinghua Road, Beijing 100083, China.
| | - Jianhan Lin
- Modern Precision Agriculture System Integration Research Key Laboratory of Ministry of Education, China Agricultural University, 17 East Qinghua Road, Beijing 100083, China.
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18
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Yang X, Song J, Zheng H, Deng X, Liu X, Lu X, Sun J, Zhao D. Anisotropic sliding on dual-rail hydrophilic tracks. LAB ON A CHIP 2017; 17:1041-1050. [PMID: 28197611 DOI: 10.1039/c7lc00028f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Biomimetic surfaces with sliding angle (SA) anisotropy have the capacity to directionally control the motion of water droplets and therefore have wide applications in various domains. Parallel and narrowing dual-rail hydrophilic tracks (DRHTs) are fabricated on etched superhydrophobic Al surfaces using a micromilling technique. Orthogonal and linear SA anisotropies are observed and investigated on the parallel and narrowing DRHTs, respectively. Track spacings of the parallel DRHTs are designed to regulate the orthogonal SA anisotropy of the water droplet. Experimental data shows that the along-track droplet-substrate interfacial widths, together with the sliding anisotropy, decrease with the increase of the track spacings. SA contrast (linear SA anisotropy) in two opposite directions along the tracks is observed and discussed on the narrowing DRHTs. Results indicate that droplets slide with more difficulty in the spacing-expanding direction than those in the shrinking direction, and when a droplet is dispensed at the tail end of a DRHT segment, the along-track outward detaching SAs and inward SAs also show sharp linear anisotropy due to the droplet-track interfacial liquid tension. On the basis of the discussed orthogonal and linear SAs, potential lab-on-a-chip applications for intelligent droplet transport, mixing and capture & release are explored.
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Affiliation(s)
- Xiaolong Yang
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China.
| | - Jinlong Song
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China. and Center of Smart Interfaces, Technische Universität Darmstadt, Darmstadt 64287, Germany
| | - Huanxi Zheng
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China.
| | - Xu Deng
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Xin Liu
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China.
| | - Xiaohong Lu
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China.
| | - Jing Sun
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China.
| | - Danyang Zhao
- Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, Dalian 116023, P. R. China.
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19
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MacConnell AB, Price AK, Paegel BM. An Integrated Microfluidic Processor for DNA-Encoded Combinatorial Library Functional Screening. ACS COMBINATORIAL SCIENCE 2017; 19:181-192. [PMID: 28199790 PMCID: PMC5350604 DOI: 10.1021/acscombsci.6b00192] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
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DNA-encoded synthesis
is rekindling interest in combinatorial compound
libraries for drug discovery and in technology for automated and quantitative
library screening. Here, we disclose a microfluidic circuit that enables
functional screens of DNA-encoded compound beads. The device carries
out library bead distribution into picoliter-scale assay reagent droplets,
photochemical cleavage of
compound from the bead, assay incubation, laser-induced fluorescence-based
assay detection, and fluorescence-activated droplet sorting to isolate
hits. DNA-encoded compound beads (10-μm diameter) displaying
a photocleavable positive control inhibitor pepstatin A were mixed
(1920 beads, 729 encoding sequences) with negative control beads (58 000
beads, 1728 encoding sequences) and screened for cathepsin D inhibition
using a biochemical enzyme activity assay. The circuit sorted 1518
hit droplets for collection following 18 min incubation over a 240
min analysis. Visual inspection of a subset of droplets (1188 droplets)
yielded a 24% false discovery rate (1166 pepstatin A beads; 366 negative
control beads). Using template barcoding strategies, it was possible
to count hit collection beads (1863) using next-generation sequencing
data. Bead-specific barcodes enabled replicate counting, and the false
discovery rate was reduced to 2.6% by only considering hit-encoding
sequences that were observed on >2 beads. This work represents
a complete
distributable small molecule discovery platform, from microfluidic
miniaturized automation to ultrahigh-throughput hit deconvolution
by sequencing.
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Affiliation(s)
- Andrew B. MacConnell
- Department
of Chemistry and ‡Doctoral Program in Chemical and Biological
Sciences, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Alexander K. Price
- Department
of Chemistry and ‡Doctoral Program in Chemical and Biological
Sciences, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Brian M. Paegel
- Department
of Chemistry and ‡Doctoral Program in Chemical and Biological
Sciences, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
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20
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Huang JP, Ge XH, Xu JH, Luo GS. Controlled formation and coalescence of paramagnetic ionic liquid droplets under magnetic field in coaxial microfluidic devices. Chem Eng Sci 2016. [DOI: 10.1016/j.ces.2016.06.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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A three-dimensional electrode for highly efficient electrocoalescence-based droplet merging. Biomed Microdevices 2016; 17:35. [PMID: 25681970 DOI: 10.1007/s10544-014-9921-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Droplet merging is one of the key functions in the ever-widening applications of droplet microfluidics. Enhancing the efficiency of electric field-based droplet merging, namely electrocoalescence, can lead to an increase in platform stability and overcome one of the major bottlenecks in further improving throughputs of droplet microfluidic systems. In this work, a paired three-dimensional (3D) electrode design that can provide a uniform electric field within a droplet merging region, which is also properly aligned with the droplet dipole moments for highly efficient electrocoalescence is presented. A systematic study was conducted to compare the droplet merging performance of the presented 3D electrode design to other commonly used planar electrode, coplanar electrode, dual-coplanar electrode, and liquid metal 3D electrode designs. The presented 3D electrode design reduced the threshold input voltage required to obtain droplet fusion by up to 75%. In addition, a droplet merging efficiency of higher than 95% was consistently observed, compared to less than 85% merging efficiency for the conventionally used electrode designs. We expect that this droplet electrocoalescence design will improve the overall throughput and merging success rate in droplet microfluidic based high-throughput assays.
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22
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23
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Shih SCC, Gach PC, Sustarich J, Simmons BA, Adams PD, Singh S, Singh AK. A droplet-to-digital (D2D) microfluidic device for single cell assays. LAB ON A CHIP 2015; 15:225-36. [PMID: 25354549 DOI: 10.1039/c4lc00794h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We have developed a new hybrid droplet-to-digital microfluidic platform (D2D) that integrates droplet-in-channel microfluidics with digital microfluidics (DMF) for performing multi-step assays. This D2D platform combines the strengths of the two formats-droplets-in-channel for facile generation of droplets containing single cells, and DMF for on-demand manipulation of droplets including control of different droplet volumes (pL-μL), creation of a dilution series of ionic liquid (IL), and parallel single cell culturing and analysis for IL toxicity screening. This D2D device also allows for automated analysis that includes a feedback-controlled system for merging and splitting of droplets to add reagents, an integrated Peltier element for parallel cell culture at optimum temperature, and an impedance sensing mechanism to control the flow rate for droplet generation and preventing droplet evaporation. Droplet-in-channel is well-suited for encapsulation of single cells as it allows the careful manipulation of flow rates of aqueous phase containing cells and oil to optimize encapsulation. Once single cell containing droplets are generated, they are transferred to a DMF chip via a capillary where they are merged with droplets containing IL and cultured at 30 °C. The DMF chip, in addition to permitting cell culture and reagent (ionic liquid/salt) addition, also allows recovery of individual droplets for off-chip analysis such as further culturing and measurement of ethanol production. The D2D chip was used to evaluate the effect of IL/salt type (four types: NaOAc, NaCl, [C2mim] [OAc], [C2mim] [Cl]) and concentration (four concentrations: 0, 37.5, 75, 150 mM) on the growth kinetics and ethanol production of yeast and as expected, increasing IL concentration led to lower biomass and ethanol production. Specifically, [C2mim] [OAc] had inhibitory effects on yeast growth at concentrations 75 and 150 mM and significantly reduced their ethanol production compared to cells grown in other ILs/salts. The growth curve trends obtained by D2D matched conventional yeast culturing in microtiter wells, validating the D2D platform. We believe that our approach represents a generic platform for multi-step biochemical assays such as drug screening, digital PCR, enzyme assays, immunoassays and cell-based assays.
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Affiliation(s)
- Steve C C Shih
- Sandia National Laboratories, 7011 East Ave, Livermore, CA, USA.
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24
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Dressler OJ, Yang T, Chang SI, Choo J, Wootton RCR, deMello AJ. Continuous and low error-rate passive synchronization of pre-formed droplets. RSC Adv 2015. [DOI: 10.1039/c5ra08044d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A microfluidic droplet-handling architecture for the synchronization of asynchronous, mis-matched, pre-formed droplet streams is demonstrated.
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Affiliation(s)
- O. J. Dressler
- Institute for Chemical and Bioengineering
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- 8093 Zürich
- Switzerland
| | - T. Yang
- Institute for Chemical and Bioengineering
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- 8093 Zürich
- Switzerland
| | - S.-I. Chang
- Department of Biochemistry
- Chungbuk National University
- Cheongju
- South Korea
| | - J. Choo
- Department of BionanoTechnology
- Hanyang University
- Ansan 426-791
- South Korea
| | - R. C. R. Wootton
- Institute for Chemical and Bioengineering
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- 8093 Zürich
- Switzerland
| | - A. J. deMello
- Institute for Chemical and Bioengineering
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- 8093 Zürich
- Switzerland
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25
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Xu L, Lee H, Brasil Pinheiro MV, Schneider P, Jetta D, Oh KW. Phaseguide-assisted blood separation microfluidic device for point-of-care applications. BIOMICROFLUIDICS 2015; 9:014106. [PMID: 25713688 PMCID: PMC4304951 DOI: 10.1063/1.4906458] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/12/2015] [Indexed: 05/08/2023]
Abstract
We propose a blood separation microfluidic device suitable for point-of-care (POC) applications. By utilizing the high gas permeability of polydimethylsiloxane (PDMS) and phaseguide structures, a simple blood separation device is presented. The device consists of two main parts. A separation chamber with the phaseguide structures, where a sample inlet, a tape-sealed outlet, and a dead-end ring channel are connected, and pneumatic chambers, in which manually operating syringes are plugged. The separation chamber and pneumatic chambers are isolated by a thin PDMS wall. By manually pulling out the plunger of the syringe, a negative pressure is instantaneously generated inside the pneumatic chamber. Due to the gas diffusion from the separation chamber to the neighboring pneumatic chamber through the thin permeable PDMS wall, low pressure can be generated, and then the whole blood at the sample inlets starts to be drawn into the separation chamber and separated through the phaseguide structures. Reversely, after removing the tape at the outlet and manually pushing in the plunger of the syringe, a positive pressure will be created which will cause the air to diffuse back into the ring channel, and therefore allow the separated plasma to be recovered at the outlet on demand. In this paper, we focused on the study of the plasma separation and associated design parameters, such as the PDMS wall thickness, the air permeable overlap area between the separation and pneumatic chambers, and the geometry of the phaseguides. The device required only 2 μl of whole blood but yielding approximately 0.38 μl of separated plasma within 12 min. Without any of the requirements of sophisticated equipment or dilution techniques, we can not only separate the plasma from the whole blood for on-chip analysis but also can push out only the separated plasma to the outlet for off-chip analysis.
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Affiliation(s)
- Linfeng Xu
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Hun Lee
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Mariana Vanderlei Brasil Pinheiro
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Phil Schneider
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Deekshitha Jetta
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Kwang W Oh
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
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26
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Lee H, Xu L, Oh KW. Droplet-based microfluidic washing module for magnetic particle-based assays. BIOMICROFLUIDICS 2014; 8:044113. [PMID: 25379098 PMCID: PMC4189219 DOI: 10.1063/1.4892495] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 07/28/2014] [Indexed: 05/06/2023]
Abstract
In this paper, we propose a continuous flow droplet-based microfluidic platform for magnetic particle-based assays by employing in-droplet washing. The droplet-based washing was implemented by traversing functionalized magnetic particles across a laterally merged droplet from one side (containing sample and reagent) to the other (containing buffer) by an external magnetic field. Consequently, the magnetic particles were extracted to a parallel-synchronized train of washing buffer droplets, and unbound reagents were left in an original train of sample droplets. To realize the droplet-based washing function, the following four procedures were sequentially carried in a droplet-based microfluidic device: parallel synchronization of two trains of droplets by using a ladder-like channel network; lateral electrocoalescence by an electric field; magnetic particle manipulation by a magnetic field; and asymmetrical splitting of merged droplets. For the stable droplet synchronization and electrocoalescence, we optimized droplet generation conditions by varying the flow rate ratio (or droplet size). Image analysis was carried out to determine the fluorescent intensity of reagents before and after the washing step. As a result, the unbound reagents in sample droplets were significantly removed by more than a factor of 25 in the single washing step, while the magnetic particles were successfully extracted into washing buffer droplets. As a proof-of-principle, we demonstrate a magnetic particle-based immunoassay with streptavidin-coated magnetic particles and fluorescently labelled biotin in the proposed continuous flow droplet-based microfluidic platform.
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Affiliation(s)
- Hun Lee
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Linfeng Xu
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
| | - Kwang W Oh
- SMALL (Sensors and MicroActuators Learning Lab), Department of Electrical Engineering, The State University of New York at Buffalo , Buffalo, New York 14260, USA
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27
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Bhattacharjee B, Vanapalli SA. Electrocoalescence based serial dilution of microfluidic droplets. BIOMICROFLUIDICS 2014; 8:044111. [PMID: 25379096 PMCID: PMC4189215 DOI: 10.1063/1.4891775] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 07/21/2014] [Indexed: 05/19/2023]
Abstract
Dilution of microfluidic droplets where the concentration of a reagent is incrementally varied is a key operation in drop-based biological analysis. Here, we present an electrocoalescence based dilution scheme for droplets based on merging between moving and parked drops. We study the effects of fluidic and electrical parameters on the dilution process. Highly consistent coalescence and fine resolution in dilution factor are achieved with an AC signal as low as 10 V even though the electrodes are separated from the fluidic channel by insulator. We find that the amount of material exchange between the droplets per coalescence event is high for low capillary number. We also observe different types of coalescence depending on the flow and electrical parameters and discuss their influence on the rate of dilution. Overall, we find the key parameter governing the rate of dilution is the duration of coalescence between the moving and parked drop. The proposed design is simple incorporating the channel electrodes in the same layer as that of the fluidic channels. Our approach allows on-demand and controlled dilution of droplets and is simple enough to be useful for assays that require serial dilutions. The approach can also be useful for applications where there is a need to replace or wash fluid from stored drops.
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Affiliation(s)
- Biddut Bhattacharjee
- Department of Chemical Engineering, Texas Tech University, Lubbock , Texas 79409, USA
| | - Siva A Vanapalli
- Department of Chemical Engineering, Texas Tech University, Lubbock , Texas 79409, USA
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28
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Deng NN, Sun SX, Wang W, Ju XJ, Xie R, Chu LY. A novel surgery-like strategy for droplet coalescence in microchannels. LAB ON A CHIP 2013; 13:3653-7. [PMID: 23877051 DOI: 10.1039/c3lc50533b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We report an innovative and efficient surgery-like strategy for achieving the coalescence of surfactant-stabilized droplets in microchannels. As pairs of preformed droplets flow across a micro-lancet, with a suitable surface wettability, in a converging microchannel simultaneously, their surfaces are scratched by the micro-lancet, which causes temporarily local scattering of surfactants, and thus induces their coalescence by joining up their scratched wounds. Our approach shows highly controllable flexibility and stability. We demonstrate this by controlling the coalescence of emulsion droplets with different numbers and complex structures. This surgery-like strategy is totally passive and has great potential in myriad applications including micro-reaction, high-throughput injection, and multiple emulsion formation, etc.
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Affiliation(s)
- Nan-Nan Deng
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
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