1
|
Harriot J, Yeh M, Pabba M, DeVoe DL. Programmable Control of Nanoliter Droplet Arrays using Membrane Displacement Traps. ADVANCED MATERIALS TECHNOLOGIES 2023; 8:2300963. [PMID: 38495529 PMCID: PMC10939115 DOI: 10.1002/admt.202300963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Indexed: 03/19/2024]
Abstract
A unique droplet microfluidic technology enabling programmable deterministic control over complex droplet operations is presented. The platform provides software control over user-defined combinations of droplet generation, capture, ejection, sorting, splitting, and merging sequences to enable the design of flexible assays employing nanoliter-scale fluid volumes. The system integrates a computer vision system with an array of membrane displacement traps capable of performing selected unit operations with automated feedback control. Sequences of individual droplet handling steps are defined through a robust Python-based scripting language. Bidirectional flow control within the microfluidic chips is provided using an H-bridge channel topology, allowing droplets to be transported to arbitrary trap locations within the array for increased operational flexibility. By enabling automated software control over all droplet operations, the system significantly expands the potential of droplet microfluidics for diverse biological and biochemical applications by combining the functionality of robotic liquid handling with the advantages of droplet-based fluid manipulation.
Collapse
Affiliation(s)
- Jason Harriot
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
- Fishell Institute for Biomedical Devices, University of Maryland, College Park, MD 20742
| | - Michael Yeh
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
- Fishell Institute for Biomedical Devices, University of Maryland, College Park, MD 20742
| | - Mani Pabba
- Department of Computer Science, University of Maryland, College Park, MD 20742
| | - Don L. DeVoe
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
- Fishell Institute for Biomedical Devices, University of Maryland, College Park, MD 20742
| |
Collapse
|
2
|
Zhu L, Tao J, Li P, Sun W, Li J, Fan K, Lv J, Qin Y, Zheng K, Zhao B, Zhao Y, Chen Y, Tang Y, Wang W, Liang J. Microfluidic static droplet generated quantum dot arrays as color conversion layers for full-color micro-LED displays. NANOSCALE ADVANCES 2023; 5:2743-2747. [PMID: 37205280 PMCID: PMC10186985 DOI: 10.1039/d2na00765g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/21/2023] [Indexed: 05/21/2023]
Abstract
This paper presents an easy and intact process based on microfluidics static droplet array (SDA) technology to fabricate quantum dot (QD) arrays for full-color micro-LED displays. A minimal sub-pixel size of 20 μm was achieved, and the fluorescence-converted red and green arrays provide good light uniformity of 98.58% and 98.72%, respectively.
Collapse
Affiliation(s)
- Licai Zhu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jin Tao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Panyuan Li
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Wenchao Sun
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jiwei Li
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - KaiLi Fan
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jinguang Lv
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yuxin Qin
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Kaifeng Zheng
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Baixuan Zhao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yingze Zhao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yupeng Chen
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yingwen Tang
- College of Physics and Information Engineering, Minnan Normal University Zhangzhou 363000 China
| | - Weibiao Wang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Jingqiu Liang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| |
Collapse
|
3
|
Hassan MR, Zhang J, Wang C. Digital Microfluidics: Magnetic Transportation and Coalescence of Sessile Droplets on Hydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:5823-5837. [PMID: 33961445 DOI: 10.1021/acs.langmuir.1c00141] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Magnetic digital microfluidics is advantageous over other existing droplet manipulation methods, which exploits magnetic forces for actuation and offers the flexibility of implementation in resource-limited point-of-care applications. This article discusses the dynamic behavior of a pair of sessile droplets on a hydrophobic surface under the presence of a permanent magnetic field. A phase field method-based solver is employed in a two-dimensional computational domain to numerically capture the dynamic evolution of the droplet interfaces, which again simultaneously solves the magnetic and flow fields. On a superhydrophobic surface (i.e., θc = 150°), the nonuniform magnetic field forces the pair of sessile droplets to move toward each other, which eventually leads to a jumping off phenomenon of the merged droplet from the solid surface after coalescence. Also, there exists a critical magnetic Bond number Bomcr, beyond which no coalescence event between droplets is observed. Moreover, on a less hydrophobic surface (θc ≤ 120°), the droplets still coalesce under a magnetic field, although the merged droplet does not experience any upward flight after coalescence. Also, the merging phenomenon at lower contact angle values (i.e., θc = 90°) appears significantly different than at higher contact angle values (i.e., θc = 120°). Additionally, if the pair of sessile droplets is dispersed to a different surrounding medium, the viscosity ratio plays a significant role in the upward flight of the merged droplet, where the coalesced droplet exhibits increased vertical migration at higher viscosity ratios.
Collapse
Affiliation(s)
- Md Rifat Hassan
- Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 400 W. 13th Street, Rolla, Missouri 65409, United States
| | - Jie Zhang
- Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 400 W. 13th Street, Rolla, Missouri 65409, United States
| | - Cheng Wang
- Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 400 W. 13th Street, Rolla, Missouri 65409, United States
| |
Collapse
|
4
|
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: 6] [Impact Index Per Article: 1.5] [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.
Collapse
|
5
|
Babahosseini H, Padmanabhan S, Misteli T, DeVoe DL. A programmable microfluidic platform for multisample injection, discretization, and droplet manipulation. BIOMICROFLUIDICS 2020; 14:014112. [PMID: 32038741 PMCID: PMC7002170 DOI: 10.1063/1.5143434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 01/26/2020] [Indexed: 05/03/2023]
Abstract
A programmable microfluidic platform enabling on-demand sampling, compartmentalization, and manipulation of multiple aqueous volumes is presented. The system provides random-access actuation of a microtrap array supporting selective discretization of picoliter volumes from multiple sample inputs. The platform comprises two interconnected chips, with parallel T-junctions and multiplexed microvalves within one chip enabling programmable injection of aqueous sample plugs, and nanoliter volumes transferred to a second microtrap array chip in which the plugs are actively discretized into picoliter droplets within a static array of membrane displacement actuators. The system employs two different multiplexer designs that reduce the number of input signals required for both sample injection and discretization. This versatile droplet-based technology offers flexible sample workflows and functionalities for the formation and manipulation of heterogeneous picoliter droplets, with particular utility for applications in biochemical synthesis and cell-based assays requiring flexible and programmable operation of parallel and multistep droplet processes. The platform is used here for the selective encapsulation of differentially labeled cells within a discrete droplet array.
Collapse
Affiliation(s)
| | - Supriya Padmanabhan
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Tom Misteli
- National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Don L. DeVoe
- Author to whom correspondence should be addressed:. Tel.: +1-301-405-8125
| |
Collapse
|
6
|
Sun M, Li Z, Wang S, Maryu G, Yang Q. Building Dynamic Cellular Machineries in Droplet-Based Artificial Cells with Single-Droplet Tracking and Analysis. Anal Chem 2019; 91:9813-9818. [PMID: 31284720 PMCID: PMC7260773 DOI: 10.1021/acs.analchem.9b01481] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although the application of droplet microfluidics has grown exponentially in chemistry and biology over the past decades, robust universal platforms for the routine generation and comprehensive analysis of droplet-based artificial cells are still rare. Here we report using microfluidic droplets to reproduce a variety of types of cellular machinery in in vitro artificial cells. In combination with a unique image-based analysis method, the system enables full automation in tracking single droplets with high accuracy, high throughput, and high sensitivity. These powerful performances allow broad applicability evident in three representative droplet-based analytical prototypes that we develop for (i) droplet digital detection, (ii) in vitro transcription and translation reactions, and (iii) spatiotemporal dynamics of cell-cycle oscillations. The capacities of this platform to generate, incubate, track, and analyze individual microdroplets via real-time, long-term imaging unleash its great potential in accelerating cell-free synthetic biology. Moreover, the wide scope covering from digital to analog to morphological detections makes this droplet analysis technique adaptable for many other divergent types of droplet-based chemical and biological assays.
Collapse
Affiliation(s)
- Meng Sun
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Zhengda Li
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Shiyuan Wang
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Gembu Maryu
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Qiong Yang
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
7
|
Suea-Ngam A, Howes PD, Srisa-Art M, deMello AJ. Droplet microfluidics: from proof-of-concept to real-world utility? Chem Commun (Camb) 2019; 55:9895-9903. [PMID: 31334541 DOI: 10.1039/c9cc04750f] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Droplet microfluidics constitutes a diverse and practical tool set that enables chemical and biological experiments to be performed at high speed and with enhanced efficiency when compared to conventional instrumentation. Indeed, in recent years, droplet-based microfluidic tools have been used to excellent effect in a range of applications, including materials synthesis, single cell analysis, RNA sequencing, small molecule screening, in vitro diagnostics and tissue engineering. Our 2011 Chemical Communications Highlight Article [Chem. Commun., 2011, 47, 1936-1942] reviewed some of the most important technological developments and applications of droplet microfluidics, and identified key challenges that needed to be addressed in the short term. In the current contribution, we consider the intervening eight years, and assess the contributions that droplet-based microfluidics has made to experimental science in its broadest sense.
Collapse
Affiliation(s)
- Akkapol Suea-Ngam
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, 8093 Zürich, Switzerland.
| | - Philip D Howes
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, 8093 Zürich, Switzerland.
| | - Monpichar Srisa-Art
- Electrochemistry and Optical Spectroscopy Center of Excellence, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok, 10330, Thailand
| | - Andrew J deMello
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, 8093 Zürich, Switzerland.
| |
Collapse
|
8
|
Sun Y, Cai B, Wei X, Wang Z, Rao L, Meng QF, Liao Q, Liu W, Guo S, Zhao X. A valve-based microfluidic device for on-chip single cell treatments. Electrophoresis 2018; 40:961-968. [PMID: 30155963 DOI: 10.1002/elps.201800213] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/19/2018] [Accepted: 08/22/2018] [Indexed: 11/08/2022]
Abstract
Assays toward single-cell analysis have attracted the attention in biological and biomedical researches to reveal cellular mechanisms as well as heterogeneity. Yet nowadays microfluidic devices for single-cell analysis have several drawbacks: some would cause cell damage due to the hydraulic forces directly acting on cells, while others could not implement biological assays since they could not immobilize cells while manipulating the reagents at the same time. In this work, we presented a two-layer pneumatic valve-based platform to implement cell immobilization and treatment on-chip simultaneously, and cells after treatment could be collected non-destructively for further analysis. Target cells could be encapsulated in sodium alginate droplets which solidified into hydrogel when reacted with Ca2+ . The size of hydrogel beads could be precisely controlled by modulating flow rates of continuous/disperse phases. While regulating fluid resistance between the main channel and passages by the integrated pneumatic valves, on-chip capture and release of hydrogel beads was implemented. As a proof of concept for on-chip single-cell treatments, we showed cellular live/dead staining based on our devices. This method would have potential in single cell manipulation for biochemical cellular assays.
Collapse
Affiliation(s)
- Yue Sun
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Bo Cai
- Research Center for Tissue Engineering and Regenerative Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Xiaoyun Wei
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Zixiang Wang
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Lang Rao
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Qian-Fang Meng
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Qingquan Liao
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Wei Liu
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Shishang Guo
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| | - Xingzhong Zhao
- School of Physics and Technology, Wuhan University, Wuhan, P. R. China
| |
Collapse
|
9
|
Hassanzadeh-Barforoushi A, Law AMK, Hejri A, Asadnia M, Ormandy CJ, Gallego-Ortega D, Ebrahimi Warkiani M. Static droplet array for culturing single live adherent cells in an isolated chemical microenvironment. LAB ON A CHIP 2018; 18:2156-2166. [PMID: 29922784 DOI: 10.1039/c8lc00403j] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We present here a new method to easily and reliably generate an array of hundreds of dispersed nanoliter-volume semi-droplets for single-cells culture and analysis. The liquid segmentation step occurs directly in indexed traps by a tweezer-like mechanism and is stabilized by spatial confinement. Unlike common droplet-based techniques, the semi-droplet wets its surrounding trap walls thus supporting the culturing of both adherent and non-adherent cells. To eliminate cross-droplet cell migration and chemical cross-talk each semi-droplet is separated from a nearby trap by an ∼80 pL air plug. The overall setup and injection procedure takes less than 10 minutes, is insensitive to fabrication defects and supports cell recovery for downstream analysis. The method offers a new approach to easily capture, image and culture single cells in a chemically isolated microenvironment as a preliminary step towards high-throughput single-cell assays.
Collapse
|
10
|
Zhang L, Liu Z, Pang Y, Wang X, Li M, Ren Y. Trapping a moving droplet train by bubble guidance in microfluidic networks. RSC Adv 2018; 8:8787-8794. [PMID: 35539830 PMCID: PMC9078607 DOI: 10.1039/c7ra13507f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/21/2018] [Indexed: 12/20/2022] Open
Abstract
Trapping a train of moving droplets into preset positions within a microfluidic device facilitates the long-term observation of biochemical reactions inside the droplets. In this paper, a new bubble-guided trapping method, which can remarkably improve the limited narrow two-phase flow rate range of uniform trapping, was proposed by taking advantage of the unique physical property that bubbles do not coalescence with two-phase fluids and the hydrodynamic characteristic of large flow resistance of bubbles. The flow behaviors of bubble-free and bubble-guided droplet trains were compared and analyzed under the same two-phase flow rates. The experimental results show that the droplets trapped by bubble-free guided trapping exhibit the four trapping modes of sequentially uniform trapping, non-uniform trapping induced by break-up and collision, and failed trapping due to squeezing through, and the droplets exhibit the desired uniform trapping in a relatively small two-phase flow rate range. Compared with bubble-free guided droplets, bubble-guided droplets also show four trapping modes. However, the two-phase flow rate range in which uniform trapping occurs is increased significantly and the uniformity of the trapped droplet array is improved. This investigation is beneficial to enhance the applicability of microfluidic chips for storing droplets in a passive way.
Collapse
Affiliation(s)
- Longxiang Zhang
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology Beijing 100124 China
| | - Zhaomiao Liu
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology Beijing 100124 China
| | - Yan Pang
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology Beijing 100124 China
| | - Xiang Wang
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology Beijing 100124 China
| | - Mengqi Li
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology Beijing 100124 China
| | - Yanlin Ren
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology Beijing 100124 China
| |
Collapse
|
11
|
Suteria NS, Nekouei M, Vanapalli SA. Microfluidic bypass manometry: highly parallelized measurement of flow resistance of complex channel geometries and trapped droplets. LAB ON A CHIP 2018; 18:343-355. [PMID: 29264612 DOI: 10.1039/c7lc00889a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Current lithography methods allow facile fabrication of microfluidic conduits where not only the shape of the bounding walls can be arbitrarily varied but also the internal conduit space can be laden with a variety of microstructures and wetting properties. This virtually infinite design space of microfluidic geometries brings in the challenge of how to quantify fluid resistance in a large number of microfluidic conduits, while maintaining operational simplicity. We report a versatile experimental technique referred to as microfluidic bypass manometry for measurement of pressure drop versus flow rate (ΔP-Q) relations in a parallelized manner. The technique involves introducing co-flowing laminar streams into a microfluidic network that contains a series of loops, where each loop is comprised of a test geometry and a bypass channel as a flow-rate sensing element. We optimize the network geometry and present operational considerations for microfluidic bypass manometry. To demonstrate the power of our technique, we used single-phase fluids and measured ΔP-Q relations simultaneously for forty test geometries ranging from linear to contraction-expansion to serpentine to pillar-laden microchannels. To expand the capabilities of the method, we measured ΔP-Q relations for similar-sized oil droplets trapped in microcavities where the cavity geometry spans from prisms of 3-10 sides to circular disks. We found in all cases, the ΔP-Q relation is nonlinear and the flow resistance of droplets is sensitive to confinement. At high flow rates, the drop resistance depends on the cavity geometry and is higher in a triangular prism compared to a circular disk. We compared the measured flow resistance of single-phase fluids and droplets in different microfluidic geometries to that from computational fluid dynamics simulations and found them to be in excellent agreement. Given the simplicity and versatility of the microfluidic bypass manometry method, we anticipate that it may find broad application in several areas including design of lab-on-chip devices, laminar drag reduction and mechanics of deformable particles.
Collapse
Affiliation(s)
- Naureen S Suteria
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX, USA.
| | | | | |
Collapse
|
12
|
Jin J, Ooi CH, Dao DV, Nguyen NT. Coalescence Processes of Droplets and Liquid Marbles. MICROMACHINES 2017; 8:mi8110336. [PMID: 30400525 PMCID: PMC6189937 DOI: 10.3390/mi8110336] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/17/2017] [Accepted: 11/18/2017] [Indexed: 01/01/2023]
Abstract
The coalescence process of droplets and, more recently, of liquid marbles, has become one of the most essential manipulation schemes in digital microfluidics. This process is indispensable for realising microfluidic functions such as mixing and reactions at microscale. This paper reviews previous studies on droplet coalescence, paying particular attention to the coalescence of liquid marbles. Four coalescence systems have been reviewed, namely, the coalescence of two droplets freely suspended in a fluid; the coalescence of two sessile droplets on a solid substrate; the coalescence of a falling droplet and a sessile droplet on a solid substrate; and liquid marble coalescence. The review is presented according to the dynamic behaviors, physical mechanisms and experimental parameters of the coalescence process. It also provides a systematic overview of how the coalescence process of droplets and liquid marbles could be induced and manipulated using external energy. In addition, the practical applications of liquid marble coalescence as a novel microreactor are highlighted. Finally, future perspectives on the investigation of the coalescence process of liquid marbles are proposed. This review aims to facilitate better understanding of the coalescence of droplets and of liquid marbles as well as to shed new insight on future studies.
Collapse
Affiliation(s)
- Jing Jin
- Queensland Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia.
| | - Chin Hong Ooi
- Queensland Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia.
| | - Dzung Viet Dao
- Queensland Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia.
| | - Nam-Trung Nguyen
- Queensland Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia.
| |
Collapse
|
13
|
Sauzade M, Brouzes E. Deterministic trapping, encapsulation and retrieval of single-cells. LAB ON A CHIP 2017; 17:2186-2192. [PMID: 28585962 PMCID: PMC5541261 DOI: 10.1039/c7lc00283a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present a novel method for conducting true single-cell encapsulation at very high efficiency for the manipulation of precious samples. Our unique strategy is based on the sequential capture and original encapsulation of single-cells into a series of hydrodynamic traps. We identified two distinct modes of encapsulation and we established their associated design rules. We improved the trapping scheme to reach a near perfect capture efficiency and make it compatible with the encapsulation process. Finally, we developed the complete device operation that permits highly efficient single-cell encapsulation and droplet retrieval. This platform provides the foundation to a fully integrated multiparameter platform that will impact the analysis of tissues at single-cell resolution.
Collapse
Affiliation(s)
- M Sauzade
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-5281, USA.
| | | |
Collapse
|
14
|
Microfluidic cell isolation technology for drug testing of single tumor cells and their clusters. Sci Rep 2017; 7:41707. [PMID: 28150812 PMCID: PMC5288702 DOI: 10.1038/srep41707] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/21/2016] [Indexed: 01/28/2023] Open
Abstract
Drug assays with patient-derived cells such as circulating tumor cells requires manipulating small sample volumes without loss of rare disease-causing cells. Here, we report an effective technology for isolating and analyzing individual tumor cells and their clusters from minute sample volumes using an optimized microfluidic device integrated with pipettes. The method involves using hand pipetting to create an array of cell-laden nanoliter-sized droplets immobilized in a microfluidic device without loss of tumor cells during the pipetting process. Using this technology, we demonstrate single-cell analysis of tumor cell response to the chemotherapy drug doxorubicin. We find that even though individual tumor cells display diverse uptake profiles of the drug, the onset of apoptosis is determined by accumulation of a critical intracellular concentration of doxorubicin. Experiments with clusters of tumor cells compartmentalized in microfluidic drops reveal that cells within a cluster have higher viability than their single-cell counterparts when exposed to doxorubicin. This result suggests that circulating tumor cell clusters might be able to better survive chemotherapy drug treatment. Our technology is a promising tool for understanding tumor cell-drug interactions in patient-derived samples including rare cells.
Collapse
|
15
|
Wang X, Liu Z, Pang Y. Concentration gradient generation methods based on microfluidic systems. RSC Adv 2017. [DOI: 10.1039/c7ra04494a] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Various concentration gradient generation methods based on microfluidic systems are summarized in this paper.
Collapse
Affiliation(s)
- Xiang Wang
- College of Mechanical Engineering and Applied Electronics Technology
- Beijing University of Technology
- Beijing 100124
- China
| | - Zhaomiao Liu
- College of Mechanical Engineering and Applied Electronics Technology
- Beijing University of Technology
- Beijing 100124
- China
| | - Yan Pang
- College of Mechanical Engineering and Applied Electronics Technology
- Beijing University of Technology
- Beijing 100124
- China
| |
Collapse
|
16
|
McMillan KS, Boyd M, Zagnoni M. Transitioning from multi-phase to single-phase microfluidics for long-term culture and treatment of multicellular spheroids. LAB ON A CHIP 2016; 16:3548-3557. [PMID: 27477673 DOI: 10.1039/c6lc00884d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
When compared to methodologies based on low adhesion or hanging drop plates, droplet microfluidics offers several advantages for the formation and culture of multicellular spheroids, such as the potential for higher throughput screening and the use of reduced cell numbers, whilst providing increased stability for plate handling. However, a drawback of the technology is its characteristic compartmentalisation which limits the nutrients available to cells within an emulsion and poses challenges to the exchange of the encapsulated solution, often resulting in short-term cell culture and/or viability issues. The aim of this study was to develop a multi-purpose microfluidic platform that combines the high-throughput characteristics of multi-phase flows with that of ease of perfusion typical of single-phase microfluidics. We developed a versatile system to upscale the formation and long-term culture of multicellular spheroids for testing anticancer treatments, creating an array of fluidically addressable, compact spheroids that could be cultured in either medium or within a gel scaffold. The work provides proof-of-concept results for using this system to test both chemo- and radio-therapeutic protocols using in vitro 3D cancer models.
Collapse
Affiliation(s)
- Kay S McMillan
- Centre for Microsystems and Photonics, Electronic and Electrical Engineering, University of Strathclyde, Glasgow, G1 1XW, UK.
| | | | | |
Collapse
|
17
|
Gupta S, Wang WS, Vanapalli SA. Microfluidic viscometers for shear rheology of complex fluids and biofluids. BIOMICROFLUIDICS 2016; 10:043402. [PMID: 27478521 PMCID: PMC4947045 DOI: 10.1063/1.4955123] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 06/21/2016] [Indexed: 05/20/2023]
Abstract
The rich diversity of man-made complex fluids and naturally occurring biofluids is opening up new opportunities for investigating their flow behavior and characterizing their rheological properties. Steady shear viscosity is undoubtedly the most widely characterized material property of these fluids. Although widely adopted, macroscale rheometers are limited by sample volumes, access to high shear rates, hydrodynamic instabilities, and interfacial artifacts. Currently, microfluidic devices are capable of handling low sample volumes, providing precision control of flow and channel geometry, enabling a high degree of multiplexing and automation, and integrating flow visualization and optical techniques. These intrinsic advantages of microfluidics have made it especially suitable for the steady shear rheology of complex fluids. In this paper, we review the use of microfluidics for conducting shear viscometry of complex fluids and biofluids with a focus on viscosity curves as a function of shear rate. We discuss the physical principles underlying different microfluidic viscometers, their unique features and limits of operation. This compilation of technological options will potentially serve in promoting the benefits of microfluidic viscometry along with evincing further interest and research in this area. We intend that this review will aid researchers handling and studying complex fluids in selecting and adopting microfluidic viscometers based on their needs. We conclude with challenges and future directions in microfluidic rheometry of complex fluids and biofluids.
Collapse
Affiliation(s)
- Siddhartha Gupta
- Department of Chemical Engineering, Texas Tech University , Lubbock, Texas 79409, USA
| | - William S Wang
- 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
| |
Collapse
|
18
|
Kaminski TS, Scheler O, Garstecki P. Droplet microfluidics for microbiology: techniques, applications and challenges. LAB ON A CHIP 2016; 16:2168-87. [PMID: 27212581 DOI: 10.1039/c6lc00367b] [Citation(s) in RCA: 245] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Droplet microfluidics has rapidly emerged as one of the key technologies opening up new experimental possibilities in microbiology. The ability to generate, manipulate and monitor droplets carrying single cells or small populations of bacteria in a highly parallel and high throughput manner creates new approaches for solving problems in diagnostics and for research on bacterial evolution. This review presents applications of droplet microfluidics in various fields of microbiology: i) detection and identification of pathogens, ii) antibiotic susceptibility testing, iii) studies of microbial physiology and iv) biotechnological selection and improvement of strains. We also list the challenges in the dynamically developing field and new potential uses of droplets in microbiology.
Collapse
Affiliation(s)
- Tomasz S Kaminski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | | | | |
Collapse
|
19
|
Derzsi L, Kaminski TS, Garstecki P. Antibiograms in five pipetting steps: precise dilution assays in sub-microliter volumes with a conventional pipette. LAB ON A CHIP 2016; 16:893-901. [PMID: 26805579 DOI: 10.1039/c5lc01151e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We demonstrate a standalone microfluidic chip that allows us to carry out commonly executed antibiotic susceptibility assays in an array of nanoliter droplets. We eliminated the need for automation in performing an exemplary complicated liquid handling assay on a chip. Operations on droplets are hard-wired into the microfluidic chip. The liquid handling protocol can be executed with a simple and commonly available source of flow such as an automatic manual pipette. The system passively prepares a series of dilutions of a chemical compound and mixes them with portions of the sample. The precision of metering, merging, mixing, and splitting of discrete portions of liquid samples is rooted in the passive capillary action in microfluidic traps and not in the precision of dosing with a pipette. We show an exemplary use of the device in the determination of the minimum inhibitory concentration (MIC) of ampicillin against E. coli ATCC 25922.
Collapse
Affiliation(s)
- Ladislav Derzsi
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland. and University of Padova, Department of Physics and Astronomy, Via Marzolo 8, 35131 Padova, Italy
| | - Tomasz S Kaminski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - Piotr Garstecki
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| |
Collapse
|
20
|
|
21
|
Bithi SS, Vanapalli SA. Collective dynamics of non-coalescing and coalescing droplets in microfluidic parking networks. SOFT MATTER 2015; 11:5122-5132. [PMID: 26036726 DOI: 10.1039/c5sm01077b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We study the complex collective dynamics mediated by flow resistance interactions when trains of non-coalescing and coalescing confined drops are introduced into a microfluidic parking network (MPN). The MPN consists of serially connected loops capable of parking arrays of drops. We define parking modes based on whether drops park without breakage or drop fragments are parked subsequent to breakage or drops park after coalescence. With both non-coalescing and coalescing drops, we map the occurrence of these parking modes in MPNs as a function of system parameters including drop volume, drop spacing and capillary number. We find that the non-coalescing drops can either park or break in the network, producing highly polydisperse arrays. We further show that parking due to collision induced droplet break-up is the main cause of polydispersity. We discover that collisions occur due to a crowding instability, which is a natural outcome of the network topology. In striking contrast, with coalescing drops we show that the ability of drops to coalesce rectifies the volume of parked polydisperse drops, despite drops breaking in the network. We find that several parking modes act in concert during this hydrodynamic self-rectification mechanism, producing highly monodisperse drop arrays over a wide operating parameter space. We demonstrate that the rectification mechanism can be harnessed to produce two-dimensional arrays of microfluidic drops with highly tunable surface-to-volume ratios, paving the way for fundamental investigations of interfacial phenomena in emulsions.
Collapse
Affiliation(s)
- Swastika S Bithi
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
| | | |
Collapse
|
22
|
Jeong HH, Jin SH, Lee BJ, Kim T, Lee CS. Microfluidic static droplet array for analyzing microbial communication on a population gradient. LAB ON A CHIP 2015; 15:889-899. [PMID: 25494004 DOI: 10.1039/c4lc01097c] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Quorum sensing (QS) is a type of cell-cell communication using signal molecules that are released and detected by cells, which respond to changes in their population density. A few studies explain that QS may operate in a density-dependent manner; however, due to experimental challenges, this fundamental hypothesis has never been investigated. Here, we present a microfluidic static droplet array (SDA) that combines a droplet generator with hydrodynamic traps to independently generate a bacterial population gradient into a parallel series of droplets under complete chemical and physical isolation. The SDA independently manipulates both a chemical concentration gradient and a bacterial population density. In addition, the bacterial population gradient in the SDA can be tuned by a simple change in the number of sample plug loading. Finally, the method allows the direct analysis of complicated biological events in an addressable droplet to enable the characterization of bacterial communication in response to the ratio of two microbial populations, including two genetically engineered QS circuits, such as the signal sender for acyl-homoserine lactone (AHL) production and the signal receiver bacteria for green fluorescent protein (GFP) expression induced by AHL. For the first time, we found that the population ratio of the signal sender and receiver indicates a significant and potentially interesting partnership between microbial communities. Therefore, we envision that this simple SDA could be a useful platform in various research fields, including analytical chemistry, combinatorial chemistry, synthetic biology, microbiology, and molecular biology.
Collapse
Affiliation(s)
- Heon-Ho Jeong
- Department of Chemical Engineering, Chungnam National University, Yuseong-gu, Daejeon 305-764, Republic of Korea.
| | | | | | | | | |
Collapse
|
23
|
Jin SH, Jeong HH, Lee B, Lee SS, Lee CS. A programmable microfluidic static droplet array for droplet generation, transportation, fusion, storage, and retrieval. LAB ON A CHIP 2015; 15:3677-86. [PMID: 26247820 DOI: 10.1039/c5lc00651a] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We present a programmable microfluidic static droplet array (SDA) device that can perform user-defined multistep combinatorial protocols. It combines the passive storage of aqueous droplets without any external control with integrated microvalves for discrete sample dispensing and dispersion-free unit operation. The addressable picoliter-volume reaction is systematically achieved by consecutively merging programmable sequences of reagent droplets. The SDA device is remarkably reusable and able to perform identical enzyme kinetic experiments at least 30 times via automated cross-contamination-free removal of droplets from individual hydrodynamic traps. Taking all these features together, this programmable and reusable universal SDA device will be a general microfluidic platform that can be reprogrammed for multiple applications.
Collapse
Affiliation(s)
- Si Hyung Jin
- Department of Chemical Engineering, Chungnam National University, Daejeon, Republic of Korea.
| | | | | | | | | |
Collapse
|
24
|
Wang WS, Vanapalli SA. Millifluidics as a simple tool to optimize droplet networks: Case study on drop traffic in a bifurcated loop. BIOMICROFLUIDICS 2014; 8:064111. [PMID: 25553188 PMCID: PMC4257966 DOI: 10.1063/1.4902910] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/17/2014] [Indexed: 05/07/2023]
Abstract
We report that modular millifluidic networks are simpler, more cost-effective alternatives to traditional microfluidic networks, and they can be rapidly generated and altered to optimize designs. Droplet traffic can also be studied more conveniently and inexpensively at the millimeter scale, as droplets are readily visible to the naked eye. Bifurcated loops, ladder networks, and parking networks were made using only Tygon(®) tubing and plastic T-junction fittings and visualized using an iPod(®) camera. As a case study, droplet traffic experiments through a millifluidic bifurcated loop were conducted, and the periodicity of drop spacing at the outlet was mapped over a wide range of inlet drop spacing. We observed periodic, intermittent, and aperiodic behaviors depending on the inlet drop spacing. The experimentally observed periodic behaviors were in good agreement with numerical simulations based on the simple network model. Our experiments further identified three main sources of intermittency between different periodic and/or aperiodic behaviors: (1) simultaneous entering and exiting events, (2) channel defects, and (3) equal or nearly equal hydrodynamic resistances in both sides of the bifurcated loop. In cases of simultaneous events and/or channel defects, the range of input spacings where intermittent behaviors are observed depends on the degree of inherent variation in input spacing. Finally, using a time scale analysis of syringe pump fluctuations and experiment observation times, we find that in most cases, more consistent results can be generated in experiments conducted at the millimeter scale than those conducted at the micrometer scale. Thus, millifluidic networks offer a simple means to probe collective interactions due to drop traffic and optimize network geometry to engineer passive devices for biological and material analysis.
Collapse
Affiliation(s)
- William S Wang
- Department of Chemical Engineering , Texas Tech University , Lubbock, Texas 79409-3121, USA
| | - Siva A Vanapalli
- Department of Chemical Engineering , Texas Tech University , Lubbock, Texas 79409-3121, USA
| |
Collapse
|
25
|
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.
Collapse
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
| |
Collapse
|
26
|
Bithi SS, Wang WS, Sun M, Blawzdziewicz J, Vanapalli SA. Coalescing drops in microfluidic parking networks: A multifunctional platform for drop-based microfluidics. BIOMICROFLUIDICS 2014; 8:034118. [PMID: 25379078 PMCID: PMC4162452 DOI: 10.1063/1.4885079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/13/2014] [Indexed: 05/06/2023]
Abstract
Multiwell plate and pipette systems have revolutionized modern biological analysis; however, they have disadvantages because testing in the submicroliter range is challenging, and increasing the number of samples is expensive. We propose a new microfluidic methodology that delivers the functionality of multiwell plates and pipettes at the nanoliter scale by utilizing drop coalescence and confinement-guided breakup in microfluidic parking networks (MPNs). Highly monodisperse arrays of drops obtained using a hydrodynamic self-rectification process are parked at prescribed locations in the device, and our method allows subsequent drop manipulations such as fine-gradation dilutions, reactant addition, and fluid replacement while retaining microparticles contained in the sample. Our devices operate in a quasistatic regime where drop shapes are determined primarily by the channel geometry. Thus, the behavior of parked drops is insensitive to flow conditions. This insensitivity enables highly parallelized manipulation of drop arrays of different composition, without a need for fine-tuning the flow conditions and other system parameters. We also find that drop coalescence can be switched off above a critical capillary number, enabling individual addressability of drops in complex MPNs. The platform demonstrated here is a promising candidate for conducting multistep biological assays in a highly multiplexed manner, using thousands of submicroliter samples.
Collapse
Affiliation(s)
- Swastika S Bithi
- Department of Chemical Engineering, Texas Tech University , Lubbock, Texas 79409-3121, USA
| | - William S Wang
- Department of Chemical Engineering, Texas Tech University , Lubbock, Texas 79409-3121, USA
| | - Meng Sun
- Department of Chemical Engineering, Texas Tech University , Lubbock, Texas 79409-3121, USA
| | - Jerzy Blawzdziewicz
- Department of Mechanical Engineering, Texas Tech University , Lubbock, Texas 79401-1021, USA
| | - Siva A Vanapalli
- Department of Chemical Engineering, Texas Tech University , Lubbock, Texas 79409-3121, USA
| |
Collapse
|