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Sample records for based microfluidic elements

  1. Discrete elements for 3D microfluidics

    PubMed Central

    Bhargava, Krisna C.; Thompson, Bryant; Malmstadt, Noah

    2014-01-01

    Microfluidic systems are rapidly becoming commonplace tools for high-precision materials synthesis, biochemical sample preparation, and biophysical analysis. Typically, microfluidic systems are constructed in monolithic form by means of microfabrication and, increasingly, by additive techniques. These methods restrict the design and assembly of truly complex systems by placing unnecessary emphasis on complete functional integration of operational elements in a planar environment. Here, we present a solution based on discrete elements that liberates designers to build large-scale microfluidic systems in three dimensions that are modular, diverse, and predictable by simple network analysis techniques. We develop a sample library of standardized components and connectors manufactured using stereolithography. We predict and validate the flow characteristics of these individual components to design and construct a tunable concentration gradient generator with a scalable number of parallel outputs. We show that these systems are rapidly reconfigurable by constructing three variations of a device for generating monodisperse microdroplets in two distinct size regimes and in a high-throughput mode by simple replacement of emulsifier subcircuits. Finally, we demonstrate the capability for active process monitoring by constructing an optical sensing element for detecting water droplets in a fluorocarbon stream and quantifying their size and frequency. By moving away from large-scale integration toward standardized discrete elements, we demonstrate the potential to reduce the practice of designing and assembling complex 3D microfluidic circuits to a methodology comparable to that found in the electronics industry. PMID:25246553

  2. Discrete elements for 3D microfluidics.

    PubMed

    Bhargava, Krisna C; Thompson, Bryant; Malmstadt, Noah

    2014-10-21

    Microfluidic systems are rapidly becoming commonplace tools for high-precision materials synthesis, biochemical sample preparation, and biophysical analysis. Typically, microfluidic systems are constructed in monolithic form by means of microfabrication and, increasingly, by additive techniques. These methods restrict the design and assembly of truly complex systems by placing unnecessary emphasis on complete functional integration of operational elements in a planar environment. Here, we present a solution based on discrete elements that liberates designers to build large-scale microfluidic systems in three dimensions that are modular, diverse, and predictable by simple network analysis techniques. We develop a sample library of standardized components and connectors manufactured using stereolithography. We predict and validate the flow characteristics of these individual components to design and construct a tunable concentration gradient generator with a scalable number of parallel outputs. We show that these systems are rapidly reconfigurable by constructing three variations of a device for generating monodisperse microdroplets in two distinct size regimes and in a high-throughput mode by simple replacement of emulsifier subcircuits. Finally, we demonstrate the capability for active process monitoring by constructing an optical sensing element for detecting water droplets in a fluorocarbon stream and quantifying their size and frequency. By moving away from large-scale integration toward standardized discrete elements, we demonstrate the potential to reduce the practice of designing and assembling complex 3D microfluidic circuits to a methodology comparable to that found in the electronics industry.

  3. Flock-based microfluidics.

    PubMed

    Hitzbleck, Martina; Lovchik, Robert D; Delamarche, Emmanuel

    2013-05-21

    Flock-based microfluidics are created by depositing hydrophilic microfibers on an adhesive-coated substrate using an electric field. This enables the fabrication of self-powered microfluidics from one or more different kinds of fibers that form 2D and 3D flowpaths, which can wick 40 microliters of liquid per square centimeter. With this approach, large areas of functional wicking materials can be produced at extremely low cost.

  4. Predicting the behavior of microfluidic circuits made from discrete elements.

    PubMed

    Bhargava, Krisna C; Thompson, Bryant; Iqbal, Danish; Malmstadt, Noah

    2015-10-30

    Microfluidic devices can be used to execute a variety of continuous flow analytical and synthetic chemistry protocols with a great degree of precision. The growing availability of additive manufacturing has enabled the design of microfluidic devices with new functionality and complexity. However, these devices are prone to larger manufacturing variation than is typical of those made with micromachining or soft lithography. In this report, we demonstrate a design-for-manufacturing workflow that addresses performance variation at the microfluidic element and circuit level, in context of mass-manufacturing and additive manufacturing. Our approach relies on discrete microfluidic elements that are characterized by their terminal hydraulic resistance and associated tolerance. Network analysis is employed to construct simple analytical design rules for model microfluidic circuits. Monte Carlo analysis is employed at both the individual element and circuit level to establish expected performance metrics for several specific circuit configurations. A protocol based on osmometry is used to experimentally probe mixing behavior in circuits in order to validate these approaches. The overall workflow is applied to two application circuits with immediate use at on the bench-top: series and parallel mixing circuits that are modularly programmable, virtually predictable, highly precise, and operable by hand.

  5. Droplet based microfluidics.

    PubMed

    Seemann, Ralf; Brinkmann, Martin; Pfohl, Thomas; Herminghaus, Stephan

    2012-01-01

    Droplet based microfluidics is a rapidly growing interdisciplinary field of research combining soft matter physics, biochemistry and microsystems engineering. Its applications range from fast analytical systems or the synthesis of advanced materials to protein crystallization and biological assays for living cells. Precise control of droplet volumes and reliable manipulation of individual droplets such as coalescence, mixing of their contents, and sorting in combination with fast analysis tools allow us to perform chemical reactions inside the droplets under defined conditions. In this paper, we will review available drop generation and manipulation techniques. The main focus of this review is not to be comprehensive and explain all techniques in great detail but to identify and shed light on similarities and underlying physical principles. Since geometry and wetting properties of the microfluidic channels are crucial factors for droplet generation, we also briefly describe typical device fabrication methods in droplet based microfluidics. Examples of applications and reaction schemes which rely on the discussed manipulation techniques are also presented, such as the fabrication of special materials and biophysical experiments.

  6. Polymer-based platform for microfluidic systems

    DOEpatents

    Benett, William; Krulevitch, Peter; Maghribi, Mariam; Hamilton, Julie; Rose, Klint; Wang, Amy W.

    2009-10-13

    A method of forming a polymer-based microfluidic system platform using network building blocks selected from a set of interconnectable network building blocks, such as wire, pins, blocks, and interconnects. The selected building blocks are interconnectably assembled and fixedly positioned in precise positions in a mold cavity of a mold frame to construct a three-dimensional model construction of a microfluidic flow path network preferably having meso-scale dimensions. A hardenable liquid, such as poly (dimethylsiloxane) is then introduced into the mold cavity and hardened to form a platform structure as well as to mold the microfluidic flow path network having channels, reservoirs and ports. Pre-fabricated elbows, T's and other joints are used to interconnect various building block elements together. After hardening the liquid the building blocks are removed from the platform structure to make available the channels, cavities and ports within the platform structure. Microdevices may be embedded within the cast polymer-based platform, or bonded to the platform structure subsequent to molding, to create an integrated microfluidic system. In this manner, the new microfluidic platform is versatile and capable of quickly generating prototype systems, and could easily be adapted to a manufacturing setting.

  7. Cell-Based Biosensors: Electrical Sensing in Microfluidic Devices

    PubMed Central

    Kiilerich-Pedersen, Katrine; Rozlosnik, Noemi

    2012-01-01

    Cell-based biosensors provide new horizons for medical diagnostics by adopting complex recognition elements such as mammalian cells in microfluidic devices that are simple, cost efficient and disposable. This combination renders possible a new range of applications in the fields of diagnostics and personalized medicine. The review looks at the most recent developments in cell-based biosensing microfluidic systems with electrical and electrochemical transduction, and relevance to medical diagnostics. PMID:26859401

  8. Mobile Monolith Polymer Elements For Flow Control In Microfluidic Systems

    DOEpatents

    Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.; Kirby, Brian J.

    2006-01-24

    A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by fluid pressure (either liquid or gas) against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

  9. Mobile monolithic polymer elements for flow control in microfluidic devices

    DOEpatents

    Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.; Kirby, Brian J.

    2005-11-11

    A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by fluid pressure (either liquid or gas) against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

  10. Mobile monolithic polymer elements for flow control in microfluidic devices

    DOEpatents

    Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.

    2004-08-31

    A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by either fluid or gas pressure against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

  11. Droplet microfluidics based microseparation systems.

    PubMed

    Xiao, Zhiliang; Niu, Menglei; Zhang, Bo

    2012-06-01

    Lab on a chip (LOC) technology is a promising miniaturization approach. The feature that it significantly reduced sample consumption makes great sense in analytical and bioanalytical chemistry. Since the start of LOC technology, much attention has been focused on continuous flow microfluidic systems. At the turn of the century, droplet microfluidics, which was also termed segmented flow microfluidics, was introduced. Droplet microfluidics employs two immiscible phases to form discrete droplets, which are ideal vessels with confined volume, restricted dispersion, limited cross-contamination, and high surface area. Due to these unique features, droplet microfluidics proves to be a versatile tool in microscale sample handling. This article reviews the utility of droplet microfluidics in microanalytical systems with an emphasize on separation science, including sample encapsulation at ultra-small volume, compartmentalization of separation bands, isolation of droplet contents, and related detection techniques.

  12. Finite element simulations of hydrodynamic trapping in microfluidic particle-trap array systems.

    PubMed

    Xu, Xiaoxiao; Li, Zhenyu; Nehorai, Arye

    2013-01-01

    Computational fluid dynamic (CFD) simulation is a powerful tool in the design and implementation of microfluidic systems, especially for systems that involve hydrodynamic behavior of objects such as functionalized microspheres, biological cells, or biopolymers in complex structures. In this work, we investigate hydrodynamic trapping of microspheres in a novel microfluidic particle-trap array device by finite element simulations. The accuracy of the time-dependent simulation of a microsphere's motion towards the traps is validated by our experimental results. Based on the simulation, we study the fluid velocity field, pressure field, and force and stress on the microsphere in the device. We further explore the trap array's geometric parameters and critical fluid velocity, which affect the microsphere's hydrodynamic trapping. The information is valuable for designing microfluidic devices and guiding experimental operation. Besides, we provide guidelines on the simulation set-up and release an openly available implementation of our simulation in one of the popular FEM softwares, COMSOL Multiphysics. Researchers may tailor the model to simulate similar microfluidic systems that may accommodate a variety of structured particles. Therefore, the simulation will be of particular interest to biomedical research involving cell or bead transport and migration, blood flow within microvessels, and drug delivery.

  13. Magneto-Hydrodynamics Based Microfluidics

    PubMed Central

    Qian, Shizhi; Bau, Haim H.

    2009-01-01

    In microfluidic devices, it is necessary to propel samples and reagents from one part of the device to another, stir fluids, and detect the presence of chemical and biological targets. Given the small size of these devices, the above tasks are far from trivial. Magnetohydrodynamics (MHD) offers an elegant means to control fluid flow in microdevices without a need for mechanical components. In this paper, we review the theory of MHD for low conductivity fluids and describe various applications of MHD such as fluid pumping, flow control in fluidic networks, fluid stirring and mixing, circular liquid chromatography, thermal reactors, and microcoolers. PMID:20046890

  14. Recent developments in microfluidics-based chemotaxis studies.

    PubMed

    Wu, Jiandong; Wu, Xun; Lin, Francis

    2013-07-07

    Microfluidic devices can better control cellular microenvironments compared to conventional cell migration assays. Over the past few years, microfluidics-based chemotaxis studies showed a rapid growth. New strategies were developed to explore cell migration in manipulated chemical gradients. In addition to expanding the use of microfluidic devices for a broader range of cell types, microfluidic devices were used to study cell migration and chemotaxis in complex environments. Furthermore, high-throughput microfluidic chemotaxis devices and integrated microfluidic chemotaxis systems were developed for medical and commercial applications. In this article, we review recent developments in microfluidics-based chemotaxis studies and discuss the new trends in this field observed over the past few years.

  15. Cell-based bioassays in microfluidic systems

    NASA Astrophysics Data System (ADS)

    Itle, Laura J.; Zguris, Jeanna C.; Pishko, Michael V.

    2004-12-01

    The development of cell-based bioassays for high throughput drug screening or the sensing of biotoxins is contingent on the development of whole cell sensors for specific changes in intracellular conditions and the integration of those systems into sample delivery devices. Here we show the feasibility of using a 5-(and-6)-carboxy SNARF-1, acetoxymethyl ester, acetate, a fluorescent dye capable of responding to changes in intracellular pH, as a detection method for the bacterial endotoxin, lipopolysaccharide. We used photolithography to entrap cells with this dye within poly(ethylene) glyocol diacrylate hydrogels in microfluidic channels. After 18 hours of exposure to lipopolysaccharide, we were able to see visible changes in the fluorescent pattern. This work shows the feasibility of using whole cell based biosensors within microfluidic networks to detect cellular changes in response to exogenous agents.

  16. Planar microcoil-based microfluidic NMR probes

    NASA Astrophysics Data System (ADS)

    Massin, C.; Vincent, F.; Homsy, A.; Ehrmann, K.; Boero, G.; Besse, P.-A.; Daridon, A.; Verpoorte, E.; de Rooij, N. F.; Popovic, R. S.

    2003-10-01

    Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300 MHz with three different probes having observed sample volumes of respectively 30, 120, and 470 nL. The achieved sensitivity enables acquisition of an 1H spectrum of 160 μg sucrose in D 2O, corresponding to a proof-of-concept for on-chip NMR spectroscopy. Increase of mass-sensitivity with coil diameter reduction is demonstrated experimentally for planar microcoils. Models that enable quantitative prediction of the signal-to-noise ratio and of the influence of microfluidic channel geometry on spectral resolution are presented and successfully compared to the experimental data. The main factor presently limiting sensitivity for high-resolution applications is identified as being probe-induced static magnetic field distortions. Finally, based on the presented model and measured data, future performance of planar microcoil-based microfluidic NMR probes is extrapolated and discussed.

  17. Planar microcoil-based microfluidic NMR probes.

    PubMed

    Massin, C; Vincent, F; Homsy, A; Ehrmann, K; Boero, G; Besse, P-A; Daridon, A; Verpoorte, E; de Rooij, N F; Popovic, R S

    2003-10-01

    Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300 MHz with three different probes having observed sample volumes of respectively 30, 120, and 470 nL. The achieved sensitivity enables acquisition of an 1H spectrum of 160 microg sucrose in D2O, corresponding to a proof-of-concept for on-chip NMR spectroscopy. Increase of mass-sensitivity with coil diameter reduction is demonstrated experimentally for planar microcoils. Models that enable quantitative prediction of the signal-to-noise ratio and of the influence of microfluidic channel geometry on spectral resolution are presented and successfully compared to the experimental data. The main factor presently limiting sensitivity for high-resolution applications is identified as being probe-induced static magnetic field distortions. Finally, based on the presented model and measured data, future performance of planar microcoil-based microfluidic NMR probes is extrapolated and discussed.

  18. Wearable tactile sensor based on flexible microfluidics.

    PubMed

    Yeo, Joo Chuan; Yu, Jiahao; Koh, Zhao Ming; Wang, Zhiping; Lim, Chwee Teck

    2016-08-16

    In this work, we develop a liquid-based thin film microfluidic tactile sensor of high flexibility, robustness and sensitivity. The microfluidic elastomeric structure comprises a pressure sensitive region and parallel arcs that interface with screen-printed electrodes. The microfluidic sensor is functionalized with a highly conductive metallic liquid, eutectic gallium indium (eGaIn). Microdeformation on the pressure sensor results in fluid displacement which corresponds to a change in electrical resistance. By emulating parallel electrical circuitry in our microchannel design, we reduced the overall electrical resistance of the sensor, therefore enhancing its device sensitivity. Correspondingly, we report a device workable within a range of 4 to 100 kPa and sensitivity of up to 0.05 kPa(-1). We further demonstrate its robustness in withstanding >2500 repeated loading and unloading cycles. Finally, as a proof of concept, we demonstrate that the sensors may be multiplexed to detect forces at multiple regions of the hand. In particular, our sensors registered unique electronic signatures in object grasping, which could provide better assessment of finger dexterity.

  19. Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials.

    PubMed

    Gao, Jun; Manard, Benjamin T; Castro, Alonso; Montoya, Dennis P; Xu, Ning; Chamberlin, Rebecca M

    2017-05-15

    Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of nine materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. The microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.

  20. Rapid wasted-free microfluidic fabrication based on ink-jet approach for microfluidic sensing applications

    NASA Astrophysics Data System (ADS)

    Jarujareet, Ungkarn; Amarit, Rattasart; Sumriddetchkajorn, Sarun

    2016-11-01

    Realizing that current microfluidic chip fabrication techniques are time consuming and labor intensive as well as always have material leftover after chip fabrication, this research work proposes an innovative approach for rapid microfluidic chip production. The key idea relies on a combination of a widely-used inkjet printing method and a heat-based polymer curing technique with an electronic-mechanical control, thus eliminating the need of masking and molds compared to typical microfluidic fabrication processes. In addition, as the appropriate amount of polymer is utilized during printing, there is much less amount of material wasted. Our inkjet-based microfluidic printer can print out the desired microfluidic chip pattern directly onto a heated glass surface, where the printed polymer is suddenly cured. Our proof-of-concept demonstration for widely-used single-flow channel, Y-junction, and T-junction microfluidic chips shows that the whole microfluidic chip fabrication process requires only 3 steps with a fabrication time of 6 minutes.

  1. Microfluidic-Based Robotic Sampling System for Radioactive Solutions

    SciTech Connect

    Jack D. Law; Julia L. Tripp; Tara E. Smith; Veronica J. Rutledge; Troy G. Garn; John Svoboda; Larry Macaluso

    2014-02-01

    A novel microfluidic based robotic sampling system has been developed for sampling and analysis of liquid solutions in nuclear processes. This system couples the use of a microfluidic sample chip with a robotic system designed to allow remote, automated sampling of process solutions in-cell and facilitates direct coupling of the microfluidic sample chip with analytical instrumentation. This system provides the capability for near real time analysis, reduces analytical waste, and minimizes the potential for personnel exposure associated with traditional sampling methods. A prototype sampling system was designed, built and tested. System testing demonstrated operability of the microfluidic based sample system and identified system modifications to optimize performance.

  2. A microfluidic device based on an evaporation-driven micropump.

    PubMed

    Nie, Chuan; Frijns, Arjan J H; Mandamparambil, Rajesh; den Toonder, Jaap M J

    2015-04-01

    In this paper we introduce a microfluidic device ultimately to be applied as a wearable sweat sensor. We show proof-of-principle of the microfluidic functions of the device, namely fluid collection and continuous fluid flow pumping. A filter-paper based layer, that eventually will form the interface between the device and the skin, is used to collect the fluid (e.g., sweat) and enter this into the microfluidic device. A controllable evaporation driven pump is used to drive a continuous fluid flow through a microfluidic channel and over a sensing area. The key element of the pump is a micro-porous membrane mounted at the channel outlet, such that a pore array with a regular hexagonal arrangement is realized through which the fluid evaporates, which drives the flow within the channel. The system is completely fabricated on flexible polyethylene terephthalate (PET) foils, which can be the backbone material for flexible electronics applications, such that it is compatible with volume production approaches like Roll-to-Roll technology. The evaporation rate can be controlled by varying the outlet geometry and the temperature. The generated flows are analyzed experimentally using Particle Tracking Velocimetry (PTV). Typical results show that with 1 to 61 pores (diameter = 250 μm, pitch = 500 μm) flow rates of 7.3 × 10(-3) to 1.2 × 10(-1) μL/min are achieved. When the surface temperature is increased by 9.4°C, the flow rate is increased by 130 %. The results are theoretically analyzed using an evaporation model that includes an evaporation correction factor. The theoretical and experimental results are in good agreement.

  3. Hybrid microfluidic systems: combining a polymer microfluidic toolbox with biosensors

    NASA Astrophysics Data System (ADS)

    Gärtner, Claudia; Kirsch, Stefanie; Anton, Birgit; Becker, Holger

    2007-01-01

    In this paper we present polymer based microfluidic chips which contain functional elements (electrodes, biosensors) made out of a different material (metals, silicon, organic semiconductors). These hybrid microfluidic devices allow the integration of additional functionality other than the simple manipulation of liquids in the chip and have been developed as a reaction to the increasing requirement for functional integration in microfluidics.

  4. Microeddies as microfluidic elements: Reactors and cell traps

    NASA Astrophysics Data System (ADS)

    Lutz, Barry R.

    2003-07-01

    Microfluidic applications generally seek to control fluids, reagents, and objects at the microscale, and the development of individual components to either mimic traditional processes or to realize novel processes remains important to development in the field. This work focuses on microscopic acoustic streaming eddies as hydrodynamic microreactors and traps for microscopic objects including motile cells. Four microeddies were created around a stationary cylinder (radius 406 mum) by oscillating the surrounding fluid (audible frequency). Concentration images measured using Raman spectroscopy show that eddies act as hydrodynamic "vessels" for reagents dosed from the cylinder (an electrode), and the oscillation amplitude and reagent dosing rate quantitatively controlled the eddy composition. These "vessels" were used to quantify the antioxidant properties of vitamin C against an electrogenerated oxidant. Material balances over the eddy yield a reactor model identical to a two-input CSTR (i.e., perfect backmixing model); and the mean reactor residence time, Damkohler number, and reagent feed ratio are quantitatively related to eddy properties. The CSTR model fit to data for a range of reactor conversions gives the homogeneous rate constant for vitamin C oxidation, showing that the composition of microeddy reactors can be controlled quantitatively. The cylinder and oscillating fluid were incorporated into microscale channels to provide a route to integration with more conventional microfluidic applications. Detailed flow measurements describe the three-dimensional acoustic streaming flow structure, and theory relates measured flow features to frequency and geometry through simple scaling. These channel-based microeddies show an impressive ability to trap microscopic objects at fixed positions in three-dimensions. Microeddies formed in a microchannel (425 mum depth) collect and trap motile phytoplankton (P. micans) and microspheres (˜20--0 mum diameter). The trap

  5. Streamline-based microfluidic device

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Kasdan, Harvey (Inventor)

    2013-01-01

    The present invention provides a streamline-based device and a method for using the device for continuous separation of particles including cells in biological fluids. The device includes a main microchannel and an array of side microchannels disposed on a substrate. The main microchannel has a plurality of stagnation points with a predetermined geometric design, for example, each of the stagnation points has a predetermined distance from the upstream edge of each of the side microchannels. The particles are separated and collected in the side microchannels.

  6. Droplet-based pyrosequencing using digital microfluidics.

    PubMed

    Boles, Deborah J; Benton, Jonathan L; Siew, Germaine J; Levy, Miriam H; Thwar, Prasanna K; Sandahl, Melissa A; Rouse, Jeremy L; Perkins, Lisa C; Sudarsan, Arjun P; Jalili, Roxana; Pamula, Vamsee K; Srinivasan, Vijay; Fair, Richard B; Griffin, Peter B; Eckhardt, Allen E; Pollack, Michael G

    2011-11-15

    The feasibility of implementing pyrosequencing chemistry within droplets using electrowetting-based digital microfluidics is reported. An array of electrodes patterned on a printed-circuit board was used to control the formation, transportation, merging, mixing, and splitting of submicroliter-sized droplets contained within an oil-filled chamber. A three-enzyme pyrosequencing protocol was implemented in which individual droplets contained enzymes, deoxyribonucleotide triphosphates (dNTPs), and DNA templates. The DNA templates were anchored to magnetic beads which enabled them to be thoroughly washed between nucleotide additions. Reagents and protocols were optimized to maximize signal over background, linearity of response, cycle efficiency, and wash efficiency. As an initial demonstration of feasibility, a portion of a 229 bp Candida parapsilosis template was sequenced using both a de novo protocol and a resequencing protocol. The resequencing protocol generated over 60 bp of sequence with 100% sequence accuracy based on raw pyrogram levels. Excellent linearity was observed for all of the homopolymers (two, three, or four nucleotides) contained in the C. parapsilosis sequence. With improvements in microfluidic design it is expected that longer reads, higher throughput, and improved process integration (i.e., "sample-to-sequence" capability) could eventually be achieved using this low-cost platform.

  7. Droplet Microfluidics for Chip-Based Diagnostics

    PubMed Central

    Kaler, Karan V. I. S.; Prakash, Ravi

    2014-01-01

    Droplet microfluidics (DMF) is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or passively control the shape and positioning of fluidic droplets over patterned substrates. In this review article, we focus on the operation and utility of electro-actuation-based DMF devices, which utilize one or more micro-/nano-patterned substrates to facilitate electric field-based handling of chemical and/or biological samples. The underlying theory of DMF actuations, device fabrication methods and integration of optical and opto-electronic detectors is discussed in this review. Example applications of such electro-actuation-based DMF devices have also been included, illustrating the various actuation methods and their utility in conducting chip-based laboratory and clinical diagnostic assays. PMID:25490590

  8. Microfluidics-Based PCR for Fusion Transcript Detection.

    PubMed

    Chen, Hui

    2016-01-01

    The microfluidic technology allows the production of network of submillimeter-size fluidic channels and reservoirs in a variety of material systems. The microfluidic-based polymerase chain reaction (PCR) allows automated multiplexing of multiple samples and multiple assays simultaneously within a network of microfluidic channels and chambers that are co-ordinated in controlled fashion by the valves. The individual PCR reaction is performed in nanoliter volume, which allows testing on samples with limited DNA and RNA. The microfluidics devices are used in various types of PCR such as digital PCR and single molecular emulsion PCR for genotyping, gene expression, and miRNA expression. In this chapter, the use of a microfluidics-based PCR for simultaneous screening of 14 known fusion transcripts in patients with leukemia is described.

  9. Microfluidic System for Solution Array Based Bioassays

    SciTech Connect

    Dougherty, G M; Tok, J B; Pannu, S S; Rose, K A

    2006-02-10

    The objective of this project is to demonstrate new enabling technology for multiplex biodetection systems that are flexible, miniaturizable, highly automated, low cost, and high performance. It builds on prior successes at LLNL with particle-based solution arrays, such as those used in the Autonomous Pathogen Detection System (APDS) successfully field deployed to multiple locations nationwide. We report the development of a multiplex solution array immunoassay based upon engineered metallic nanorod particles. Nanobarcodes{reg_sign} particles are fabricated by sequential electrodeposition of dissimilar metals within porous alumina templates, yielding optically encoded striping patterns that can be read using standard laboratory microscope optics and PC-based image processing software. The addition of self-assembled monolayer (SAM) coatings and target-specific antibodies allows each encoded class of nanorod particles to be directed against a different antigen target. A prototype assay panel directed against bacterial, viral, and soluble protein targets demonstrates simultaneous detection at sensitivities comparable to state of the art immunoassays, with minimal cross-reactivity. Studies have been performed to characterize the colloidal properties (zeta potential) of the suspended nanorod particles as a function of pH, the ionic strength of the suspending solution, and surface functionalization state. Additional studies have produced means for the non-contact manipulation of the particles, including the insertion of magnetic nickel stripes within the encoding pattern, and control via externally applied electromagnetic fields. Using the results of these studies, the novel Nanobarcodes{reg_sign} based assay was implemented in a prototype automated system with the sample processing functions and optical readout performed on a microfluidic card. The unique physical properties of the nanorod particles enable the development of integrated microfluidic systems for

  10. Reciprocating flow-based centrifugal microfluidics mixer

    NASA Astrophysics Data System (ADS)

    Noroozi, Zahra; Kido, Horacio; Micic, Miodrag; Pan, Hansheng; Bartolome, Christian; Princevac, Marko; Zoval, Jim; Madou, Marc

    2009-07-01

    Proper mixing of reagents is of paramount importance for an efficient chemical reaction. While on a large scale there are many good solutions for quantitative mixing of reagents, as of today, efficient and inexpensive fluid mixing in the nanoliter and microliter volume range is still a challenge. Complete, i.e., quantitative mixing is of special importance in any small-scale analytical application because the scarcity of analytes and the low volume of the reagents demand efficient utilization of all available reaction components. In this paper we demonstrate the design and fabrication of a novel centrifugal force-based unit for fast mixing of fluids in the nanoliter to microliter volume range. The device consists of a number of chambers (including two loading chambers, one pressure chamber, and one mixing chamber) that are connected through a network of microchannels, and is made by bonding a slab of polydimethylsiloxane (PDMS) to a glass slide. The PDMS slab was cast using a SU-8 master mold fabricated by a two-level photolithography process. This microfluidic mixer exploits centrifugal force and pneumatic pressure to reciprocate the flow of fluid samples in order to minimize the amount of sample and the time of mixing. The process of mixing was monitored by utilizing the planar laser induced fluorescence (PLIF) technique. A time series of high resolution images of the mixing chamber were analyzed for the spatial distribution of light intensities as the two fluids (suspension of red fluorescent particles and water) mixed. Histograms of the fluorescent emissions within the mixing chamber during different stages of the mixing process were created to quantify the level of mixing of the mixing fluids. The results suggest that quantitative mixing was achieved in less than 3 min. This device can be employed as a stand alone mixing unit or may be integrated into a disk-based microfluidic system where, in addition to mixing, several other sample preparation steps may be

  11. Computational analysis of enhanced magnetic bioseparation in microfluidic systems with flow-invasive magnetic elements.

    PubMed

    Khashan, S A; Alazzam, A; Furlani, E P

    2014-06-16

    A microfluidic design is proposed for realizing greatly enhanced separation of magnetically-labeled bioparticles using integrated soft-magnetic elements. The elements are fixed and intersect the carrier fluid (flow-invasive) with their length transverse to the flow. They are magnetized using a bias field to produce a particle capture force. Multiple stair-step elements are used to provide efficient capture throughout the entire flow channel. This is in contrast to conventional systems wherein the elements are integrated into the walls of the channel, which restricts efficient capture to limited regions of the channel due to the short range nature of the magnetic force. This severely limits the channel size and hence throughput. Flow-invasive elements overcome this limitation and enable microfluidic bioseparation systems with superior scalability. This enhanced functionality is quantified for the first time using a computational model that accounts for the dominant mechanisms of particle transport including fully-coupled particle-fluid momentum transfer.

  12. Characterization of Fluid Flow in Paper-Based Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Walji, Noosheen; MacDonald, Brendan

    2014-11-01

    Paper-based microfluidic devices have been presented as a viable low-cost alternative with the versatility to accommodate many applications in disease diagnosis and environmental monitoring. Current microfluidic designs focus on the use of silicone and PDMS structures, and several models have been developed to describe these systems; however, the design process for paper-based devices is hindered by a lack of prediction capability. In this work we simplify the complex underlying physics of the capillary-driven flow mechanism in a porous medium and generate a practical numerical model capable of predicting the flow behaviour. We present our key insights regarding the properties that dictate the behaviour of fluid wicking in paper-based microfluidic devices. We compare the results from our model to experiments and discuss the application of our model to design of paper-based microfluidic devices for arsenic detection in drinking water in Bangladesh.

  13. Electrocoalescence based serial dilution of microfluidic droplets.

    PubMed

    Bhattacharjee, Biddut; Vanapalli, Siva A

    2014-07-01

    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.

  14. Electrocoalescence based serial dilution of microfluidic droplets

    PubMed Central

    Bhattacharjee, Biddut; Vanapalli, Siva A.

    2014-01-01

    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. PMID:25379096

  15. Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

    DOE PAGES

    Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso; ...

    2017-02-02

    Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

  16. Silicon based microfluidic cell for terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Baragwanath, A. J.; Swift, G. P.; Dai, D.; Gallant, A. J.; Chamberlain, J. M.

    2010-07-01

    We present a detailed analysis of the design, fabrication and testing of a silicon based, microfluidic cell, for transmission terahertz time-domain spectroscopy. The sensitivity of the device is tested through a range of experiments involving primary alcohol/water mixtures. The dielectric properties of these solutions are subsequently extracted using a Nelder-Mead search algorithm, and are in good agreement with literature values obtained via alternative techniques. Quantities in the order of 2 μmol can be easily distinguished for primary alcohols in solution, even with the subwavelength optical path lengths used. A further display of the device sensitivity is shown through the analysis of commercial whiskeys, where there are clear, detectable differences between samples. Slight absorption variations were identified between samples of the same commercial brand, owing to a 2.5% difference in their alcoholic content. Results from data taken on subsequent days after system realignment are also presented, confirming the robustness of the technique, and the data extraction algorithm used. One final experiment, showing the possible use of this device to analyze aqueous biological samples is detailed; where biotin, a molecule known for its specific terahertz absorptions, is analyzed in solution. The device sensitivity is once again displayed, where quantities of 3 nmol can be clearly detected between samples.

  17. Thermally induced light-driven microfluidics using a MOEMS-based laser scanner for particle manipulation

    NASA Astrophysics Data System (ADS)

    Kremer, Matthias P.; Tortschanoff, Andreas

    2014-03-01

    One key challenge in the field of microfluidics and lab-on-a-chip experiments for biological or chemical applications is the remote manipulation of fluids, droplets and particles. These can be volume elements of reactants, particles coated with markers, cells or many others. Light-driven microfluidics is one way of accomplishing this challenge. In our work, we manipulated micrometre sized polystyrene beads in a microfluidic environment by inducing thermal flows. Therefore, the beads were held statically in an unstructured microfluidic chamber, containing a dyed watery solution. Inside this chamber, the beads were moved along arbitrary trajectories on a micrometre scale. The experiments were performed, using a MOEMS (micro-opto-electro-mechanical-systems)-based laser scanner with a variable focal length. This scanner system is integrated in a compact device, which is flexibly applicable to various microscope setups. The device utilizes a novel approach for varying the focal length, using an electrically tunable lens. A quasi statically driven MOEMS mirror is used for beam steering. The combination of a tunable lens and a dual axis micromirror makes the device very compact and robust and is capable of positioning the laser focus at any arbitrary location within a three dimensional working space. Hence, the developed device constitutes a valuable extension to manually executed microfluidic lab-on-chip experiments.

  18. Nanopillar based electrochemical biosensor for monitoring microfluidic based cell culture

    NASA Astrophysics Data System (ADS)

    Gangadharan, Rajan

    In-vitro assays using cultured cells have been widely performed for studying many aspects of cell biology and cell physiology. These assays also form the basis of cell based sensing. Presently, analysis procedures on cell cultures are done using techniques that are not integrated with the cell culture system. This approach makes continuous and real-time in-vitro measurements difficult. It is well known that the availability of continuous online measurements for extended periods of time will help provide a better understanding and will give better insight into cell physiological events. With this motivation we developed a highly sensitive, selective and stable microfluidic electrochemical glucose biosensor to make continuous glucose measurements in cell culture media. The performance of the microfluidic biosensor was enhanced by adding 3D nanopillars to the electrode surfaces. The microfluidic glucose biosensor consisted of three electrodes---Enzyme electrode, Working electrode, and Counter electrode. All these electrodes were enhanced with nanopillars and were optimized in their respective own ways to obtain an effective and stable biosensing device in cell culture media. For example, the 'Enzyme electrode' was optimized for enzyme immobilization via either a polypyrrole-based or a self-assembled-monolayer-based immobilization method, and the 'Working electrode' was modified with Prussian Blue or electropolymerized Neutral Red to reduce the working potential and also the interference from other interacting electro-active species. The complete microfluidic biosensor was tested for its ability to monitor glucose concentration changes in cell culture media. The significance of this work is multifold. First, the developed device may find applications in continuous and real-time measurements of glucose concentrations in in-vitro cell cultures. Second, the development of a microfluidic biosensor will bring technical know-how toward constructing continuous glucose

  19. A microfluidic-based hydrodynamic trap: design and implementation.

    PubMed

    Tanyeri, Melikhan; Ranka, Mikhil; Sittipolkul, Natawan; Schroeder, Charles M

    2011-05-21

    We report an integrated microfluidic device for fine-scale manipulation and confinement of micro- and nanoscale particles in free-solution. Using this device, single particles are trapped in a stagnation point flow at the junction of two intersecting microchannels. The hydrodynamic trap is based on active flow control at a fluid stagnation point using an integrated on-chip valve in a monolithic PDMS-based microfluidic device. In this work, we characterize device design parameters enabling precise control of stagnation point position for efficient trap performance. The microfluidic-based hydrodynamic trap facilitates particle trapping using the sole action of fluid flow and provides a viable alternative to existing confinement and manipulation techniques based on electric, optical, magnetic or acoustic force fields. Overall, the hydrodynamic trap enables non-contact confinement of fluorescent and non-fluorescent particles for extended times and provides a new platform for fundamental studies in biology, biotechnology and materials science.

  20. Microfluidic systems for stem cell-based neural tissue engineering.

    PubMed

    Karimi, Mahdi; Bahrami, Sajad; Mirshekari, Hamed; Basri, Seyed Masoud Moosavi; Nik, Amirala Bakhshian; Aref, Amir R; Akbari, Mohsen; Hamblin, Michael R

    2016-07-05

    Neural tissue engineering aims at developing novel approaches for the treatment of diseases of the nervous system, by providing a permissive environment for the growth and differentiation of neural cells. Three-dimensional (3D) cell culture systems provide a closer biomimetic environment, and promote better cell differentiation and improved cell function, than could be achieved by conventional two-dimensional (2D) culture systems. With the recent advances in the discovery and introduction of different types of stem cells for tissue engineering, microfluidic platforms have provided an improved microenvironment for the 3D-culture of stem cells. Microfluidic systems can provide more precise control over the spatiotemporal distribution of chemical and physical cues at the cellular level compared to traditional systems. Various microsystems have been designed and fabricated for the purpose of neural tissue engineering. Enhanced neural migration and differentiation, and monitoring of these processes, as well as understanding the behavior of stem cells and their microenvironment have been obtained through application of different microfluidic-based stem cell culture and tissue engineering techniques. As the technology advances it may be possible to construct a "brain-on-a-chip". In this review, we describe the basics of stem cells and tissue engineering as well as microfluidics-based tissue engineering approaches. We review recent testing of various microfluidic approaches for stem cell-based neural tissue engineering.

  1. Three-Dimensional Printing Based Hybrid Manufacturing of Microfluidic Devices.

    PubMed

    Alapan, Yunus; Hasan, Muhammad Noman; Shen, Richang; Gurkan, Umut A

    2015-05-01

    Microfluidic platforms offer revolutionary and practical solutions to challenging problems in biology and medicine. Even though traditional micro/nanofabrication technologies expedited the emergence of the microfluidics field, recent advances in advanced additive manufacturing hold significant potential for single-step, stand-alone microfluidic device fabrication. One such technology, which holds a significant promise for next generation microsystem fabrication is three-dimensional (3D) printing. Presently, building 3D printed stand-alone microfluidic devices with fully embedded microchannels for applications in biology and medicine has the following challenges: (i) limitations in achievable design complexity, (ii) need for a wider variety of transparent materials, (iii) limited z-resolution, (iv) absence of extremely smooth surface finish, and (v) limitations in precision fabrication of hollow and void sections with extremely high surface area to volume ratio. We developed a new way to fabricate stand-alone microfluidic devices with integrated manifolds and embedded microchannels by utilizing a 3D printing and laser micromachined lamination based hybrid manufacturing approach. In this new fabrication method, we exploit the minimized fabrication steps enabled by 3D printing, and reduced assembly complexities facilitated by laser micromachined lamination method. The new hybrid fabrication method enables key features for advanced microfluidic system architecture: (i) increased design complexity in 3D, (ii) improved control over microflow behavior in all three directions and in multiple layers, (iii) transverse multilayer flow and precisely integrated flow distribution, and (iv) enhanced transparency for high resolution imaging and analysis. Hybrid manufacturing approaches hold great potential in advancing microfluidic device fabrication in terms of standardization, fast production, and user-independent manufacturing.

  2. Micro Electromechanical Systems (MEMS) Based Microfluidic Devices for Biomedical Applications.

    PubMed

    Ashraf, Muhammad Waseem; Tayyaba, Shahzadi; Afzulpurkar, Nitin

    2011-01-01

    Micro Electromechanical Systems (MEMS) based microfluidic devices have gained popularity in biomedicine field over the last few years. In this paper, a comprehensive overview of microfluidic devices such as micropumps and microneedles has been presented for biomedical applications. The aim of this paper is to present the major features and issues related to micropumps and microneedles, e.g., working principles, actuation methods, fabrication techniques, construction, performance parameters, failure analysis, testing, safety issues, applications, commercialization issues and future prospects. Based on the actuation mechanisms, the micropumps are classified into two main types, i.e., mechanical and non-mechanical micropumps. Microneedles can be categorized according to their structure, fabrication process, material, overall shape, tip shape, size, array density and application. The presented literature review on micropumps and microneedles will provide comprehensive information for researchers working on design and development of microfluidic devices for biomedical applications.

  3. Micro Electromechanical Systems (MEMS) Based Microfluidic Devices for Biomedical Applications

    PubMed Central

    Ashraf, Muhammad Waseem; Tayyaba, Shahzadi; Afzulpurkar, Nitin

    2011-01-01

    Micro Electromechanical Systems (MEMS) based microfluidic devices have gained popularity in biomedicine field over the last few years. In this paper, a comprehensive overview of microfluidic devices such as micropumps and microneedles has been presented for biomedical applications. The aim of this paper is to present the major features and issues related to micropumps and microneedles, e.g., working principles, actuation methods, fabrication techniques, construction, performance parameters, failure analysis, testing, safety issues, applications, commercialization issues and future prospects. Based on the actuation mechanisms, the micropumps are classified into two main types, i.e., mechanical and non-mechanical micropumps. Microneedles can be categorized according to their structure, fabrication process, material, overall shape, tip shape, size, array density and application. The presented literature review on micropumps and microneedles will provide comprehensive information for researchers working on design and development of microfluidic devices for biomedical applications. PMID:21747700

  4. Microfluidic chip-based technologies: emerging platforms for cancer diagnosis

    PubMed Central

    2013-01-01

    The development of early and personalized diagnostic protocols is considered the most promising avenue to decrease mortality from cancer and improve outcome. The emerging microfluidic-based analyzing platforms hold high promises to fulfill high-throughput and high-precision screening with reduced equipment cost and low analysis time, as compared to traditional bulky counterparts in bench-top laboratories. This article overviewed the potential applications of microfluidic technologies for detection and monitoring of cancer through nucleic acid and protein biomarker analysis. The implications of the technologies in cancer cytology that can provide functional personalized diagnosis were highlighted. Finally, the future niches for using microfluidic-based systems in tumor screening were briefly discussed. PMID:24070124

  5. Orientation-Based Control of Microfluidics

    PubMed Central

    Norouzi, Nazila; Bhakta, Heran C.; Grover, William H.

    2016-01-01

    Most microfluidic chips utilize off-chip hardware (syringe pumps, computer-controlled solenoid valves, pressure regulators, etc.) to control fluid flow on-chip. This expensive, bulky, and power-consuming hardware severely limits the utility of microfluidic instruments in resource-limited or point-of-care contexts, where the cost, size, and power consumption of the instrument must be limited. In this work, we present a technique for on-chip fluid control that requires no off-chip hardware. We accomplish this by using inert compounds to change the density of one fluid in the chip. If one fluid is made 2% more dense than a second fluid, when the fluids flow together under laminar flow the interface between the fluids quickly reorients to be orthogonal to Earth’s gravitational force. If the channel containing the fluids then splits into two channels, the amount of each fluid flowing into each channel is precisely determined by the angle of the channels relative to gravity. Thus, any fluid can be routed in any direction and mixed in any desired ratio on-chip simply by holding the chip at a certain angle. This approach allows for sophisticated control of on-chip fluids with no off-chip control hardware, significantly reducing the cost of microfluidic instruments in point-of-care or resource-limited settings. PMID:26950700

  6. Graphene-based microfluidics for serial crystallography.

    PubMed

    Sui, Shuo; Wang, Yuxi; Kolewe, Kristopher W; Srajer, Vukica; Henning, Robert; Schiffman, Jessica D; Dimitrakopoulos, Christos; Perry, Sarah L

    2016-08-02

    Microfluidic strategies to enable the growth and subsequent serial crystallographic analysis of micro-crystals have the potential to facilitate both structural characterization and dynamic structural studies of protein targets that have been resistant to single-crystal strategies. However, adapting microfluidic crystallization platforms for micro-crystallography requires a dramatic decrease in the overall device thickness. We report a robust strategy for the straightforward incorporation of single-layer graphene into ultra-thin microfluidic devices. This architecture allows for a total material thickness of only ∼1 μm, facilitating on-chip X-ray diffraction analysis while creating a sample environment that is stable against significant water loss over several weeks. We demonstrate excellent signal-to-noise in our X-ray diffraction measurements using a 1.5 μs polychromatic X-ray exposure, and validate our approach via on-chip structure determination using hen egg white lysozyme (HEWL) as a model system. Although this work is focused on the use of graphene for protein crystallography, we anticipate that this technology should find utility in a wide range of both X-ray and other lab on a chip applications.

  7. Characterization of light-controlled Volvox as movable microvalve element assembled in multilayer microfluidic device

    NASA Astrophysics Data System (ADS)

    Nagai, Moeto; Oguri, Michihito; Shibata, Takayuki

    2015-06-01

    We report a model of a light-controlled microvalve driven by Volvox and characterization of Volvox as a movable microvalve element in a multilayer microfluidic device for development of the valve. First, a three-layer microfluidic device having a single through-hole was fabricated by a replica molding process. The fabricated devices met the requirements for experiments using Volvox. Second, we used the phototactic behavior of V. carteri and controlled its motions in a microchannel by illuminating light. V. carteri migrated to the light source in the channel. Third, a colony of V. carteri was placed on a microhole, and the colony was found to stop the flow compared to the flow without Volvox on the hole. The integration of all of the obtained findings is expected to lead to the fabrication of the proposed microvalve.

  8. Computational Analysis of Enhanced Magnetic Bioseparation in Microfluidic Systems with Flow-Invasive Magnetic Elements

    PubMed Central

    Khashan, S. A.; Alazzam, A.; Furlani, E. P.

    2014-01-01

    A microfluidic design is proposed for realizing greatly enhanced separation of magnetically-labeled bioparticles using integrated soft-magnetic elements. The elements are fixed and intersect the carrier fluid (flow-invasive) with their length transverse to the flow. They are magnetized using a bias field to produce a particle capture force. Multiple stair-step elements are used to provide efficient capture throughout the entire flow channel. This is in contrast to conventional systems wherein the elements are integrated into the walls of the channel, which restricts efficient capture to limited regions of the channel due to the short range nature of the magnetic force. This severely limits the channel size and hence throughput. Flow-invasive elements overcome this limitation and enable microfluidic bioseparation systems with superior scalability. This enhanced functionality is quantified for the first time using a computational model that accounts for the dominant mechanisms of particle transport including fully-coupled particle-fluid momentum transfer. PMID:24931437

  9. Standing surface acoustic wave (SSAW)-based microfluidic cytometer

    PubMed Central

    Chen, Yuchao; Nawaz, Ahmad Ahsan; Zhao, Yanhui; Huang, Po-Hsun; McCoy, J. Phillip; Levine, Stewart; Wang, Lin; Huang, Tony Jun

    2014-01-01

    The development of microfluidic chip-based cytometers has become an important area due to their advantages of compact size and low cost. Herein, we demonstrate a sheathless microfluidic cytometer which integrates a standing surface acoustic wave (SSAW)-based microdevice capable of 3D particle/cell focusing with a laser-induced fluorescence (LIF) detection system. Using SSAW, our microfluidic cytometer was able to continuously focus microparticles/cells at the pressure node inside a microchannel. Flow cytometry was successfully demonstrated using this system with a coefficient of variation (CV) of less than 10% at a throughput of ~1000 events/s when calibration beads were used. We also demonstrated that fluorescently labeled human promyelocytic leukemia cells (HL-60) could be effectively focused and detected with our SSAW-based system. This SSAW-based microfluidic cytometer did not require any sheath flows or complex structures, and it allowed for simple operation over a wide range of sample flow rates. Moreover, with the gentle, bio-compatible nature of low-power surface acoustic waves, this technique is expected to be able to preserve the integrity of cells and other bioparticles. PMID:24406848

  10. Hybrid Integrated Silicon Microfluidic Platform for Fluorescence Based Biodetection

    PubMed Central

    Chandrasekaran, Arvind; Acharya, Ashwin; You, Jian Liang; Soo, Kim Young; Packirisamy, Muthukumaran; Stiharu, Ion; Darveau, Andre

    2007-01-01

    The desideratum to develop a fully integrated Lab-on-a-chip device capable of rapid specimen detection for high throughput in-situ biomedical diagnoses and Point-of-Care testing applications has called for the integration of some of the novel technologies such as the microfluidics, microphotonics, immunoproteomics and Micro Electro Mechanical Systems (MEMS). In the present work, a silicon based microfluidic device has been developed for carrying out fluorescence based immunoassay. By hybrid attachment of the microfluidic device with a Spectrometer-on-chip, the feasibility of synthesizing an integrated Lab-on-a-chip type device for fluorescence based biosensing has been demonstrated. Biodetection using the microfluidic device has been carried out using antigen sheep IgG and Alexafluor-647 tagged antibody particles and the experimental results prove that silicon is a compatible material for the present application given the various advantages it offers such as cost-effectiveness, ease of bulk microfabrication, superior surface affinity to biomolecules, ease of disposability of the device etc., and is thus suitable for fabricating Lab-on-a-chip type devices.

  11. A multi-functional bubble-based microfluidic system

    PubMed Central

    Khoshmanesh, Khashayar; Almansouri, Abdullah; Albloushi, Hamad; Yi, Pyshar; Soffe, Rebecca; Kalantar-zadeh, Kourosh

    2015-01-01

    Recently, the bubble-based systems have offered a new paradigm in microfluidics. Gas bubbles are highly flexible, controllable and barely mix with liquids, and thus can be used for the creation of reconfigurable microfluidic systems. In this work, a hydrodynamically actuated bubble-based microfluidic system is introduced. This system enables the precise movement of air bubbles via axillary feeder channels to alter the geometry of the main channel and consequently the flow characteristics of the system. Mixing of neighbouring streams is demonstrated by oscillating the bubble at desired displacements and frequencies. Flow control is achieved by pushing the bubble to partially or fully close the main channel. Patterning of suspended particles is also demonstrated by creating a large bubble along the sidewalls. Rigorous analytical and numerical calculations are presented to describe the operation of the system. The examples presented in this paper highlight the versatility of the developed bubble-based actuator for a variety of applications; thus providing a vision that can be expanded for future highly reconfigurable microfluidics. PMID:25906043

  12. Assessment of mesoscopic particle-based methods in microfluidic geometries

    NASA Astrophysics Data System (ADS)

    Zhao, Tongyang; Wang, Xiaogong; Jiang, Lei; Larson, Ronald G.

    2013-08-01

    We assess the accuracy and efficiency of two particle-based mesoscopic simulation methods, namely, Dissipative Particle Dynamics (DPD) and Stochastic Rotation Dynamics (SRD) for predicting a complex flow in a microfluidic geometry. Since both DPD and SRD use soft or weakly interacting particles to carry momentum, both methods contain unavoidable inertial effects and unphysically high fluid compressibility. To assess these effects, we compare the predictions of DPD and SRD for both an exact Stokes-flow solution and nearly exact solutions at finite Reynolds numbers from the finite element method for flow in a straight channel with periodic slip boundary conditions. This flow represents a periodic electro-osmotic flow, which is a complex flow with an analytical solution for zero Reynolds number. We find that SRD is roughly ten-fold faster than DPD in predicting the flow field, with better accuracy at low Reynolds numbers. However, SRD has more severe problems with compressibility effects than does DPD, which limits the Reynolds numbers attainable in SRD to around 25-50, while DPD can achieve Re higher than this before compressibility effects become too large. However, since the SRD method runs much faster than DPD does, we can afford to enlarge the number of grid cells in SRD to reduce the fluid compressibility at high Reynolds number. Our simulations provide a method to estimate the range of conditions for which SRD or DPD is preferable for mesoscopic simulations.

  13. Bead-based microfluidic immunoassay for diagnosis of Johne's disease

    SciTech Connect

    Wadhwa, Ashutosh; Foote, Robert; Shaw, Robert W; Eda, Shigetoshi

    2012-01-01

    Microfluidics technology offers a platform for development of point-of-care diagnostic devices for various infectious diseases. In this study, we examined whether serodiagnosis of Johne s disease (JD) can be conducted in a bead-based microfluidic assay system. Magnetic micro-beads were coated with antigens of the causative agent of JD, Mycobacterium avium subsp. paratuberculosis. The antigen-coated beads were incubated with serum samples of JD-positive or negative serum samples and then with a fluorescently-labeled secondary antibody (SAB). To confirm binding of serum antibodies to the antigen, the beads were subjected to flow cytometric analysis. Different conditions (dilutions of serum and SAB, types of SAB, and types of magnetic beads) were optimized for a great degree of differentiation between the JD-negative and JD-positive samples. Using the optimized conditions, we tested a well-classified set of 155 serum samples from JD negative and JD-positive cattle by using the bead-based flow cytometric assay. Of 105 JD-positive samples, 63 samples (60%) showed higher antibody binding levels than a cut-off value determined by using antibody binding levels of JD-negative samples. In contrast, only 43-49 JD-positive samples showed higher antibody binding levels than the cut-off value when the samples were tested by commercially-available immunoassays. Microfluidic assays were performed by magnetically immobilizing a number of beads within a microchannel of a glass microchip and detecting antibody on the collected beads by laser-induced fluorescence. Antigen-coated magnetic beads treated with bovine serum sample and fluorescently-labeled SAB were loaded into a microchannel to measure the fluorescence (reflecting level of antibody binding) on the beads in the microfluidic system. When the results of five bovine serum samples obtained with the system were compared to those obtained with the flow cytometer, a high level of correlation (linear regression, r2 = 0.994) was

  14. "Hot-wire" microfluidic flowmeter based on a microfiber coupler.

    PubMed

    Yan, Shao-Cheng; Liu, Zeng-Yong; Li, Cheng; Ge, Shi-Jun; Xu, Fei; Lu, Yan-Qing

    2016-12-15

    Using an optical microfiber coupler (MC), we present a microfluidic platform for strong direct or indirect light-liquid interaction by wrapping a MC around a functionalized capillary. The light propagating in the MC and the liquid flowing in the capillary can be combined and divorced smoothly, keeping a long-distance interaction without the conflict of input and output coupling. Using this approach, we experimentally demonstrate a "hot-wire" microfluidic flowmeter based on a gold-integrated helical MC device. The microfluid inside the glass channel takes away the heat, then cools the MC and shifts the resonant wavelength. Due to the long-distance interaction and high temperature sensitivity, the proposed microfluidic flowmeter shows an ultrahigh flow rate sensitivity of 2.183 nm/(μl/s) at a flow rate of 1 μl/s. The minimum detectable change of the flow rate is around 9 nl/s at 1 μl/s.

  15. Towards non- and minimally instrumented, microfluidics-based diagnostic devices†

    PubMed Central

    Weigl, Bernhard; Domingo, Gonzalo; LaBarre, Paul; Gerlach, Jay

    2009-01-01

    In many health care settings, it is uneconomical, impractical, or unaffordable to maintain and access a fully equipped diagnostics laboratory. Examples include home health care, developing-country health care, and emergency situations in which first responders are dealing with pandemics or biowarfare agent release. In those settings, fully disposable diagnostic devices that require no instrument support, reagent, or significant training are well suited. Although the only such technology to have found widespread adoption so far is the immunochromatographic rapid assay strip test, microfluidics holds promise to expand the range of assay technologies that can be performed in formats similar to that of a strip test. In this paper, we review progress toward development of disposable, low-cost, easy-to-use microfluidics-based diagnostics that require no instrument at all. We also present examples of microfluidic functional elements—including mixers, separators, and detectors—as well as complete microfluidic devices that function entirely without any moving parts and external power sources. PMID:19023463

  16. Paper-based microfluidic system for tear electrolyte analysis.

    PubMed

    Yetisen, Ali K; Jiang, Nan; Tamayol, Ali; Ruiz-Esparza, Guillermo U; Zhang, Yu Shrike; Medina-Pando, Sofía; Gupta, Aditi; Wolffsohn, James S; Butt, Haider; Khademhosseini, Ali; Yun, Seok-Hyun

    2017-03-14

    The analysis of tear constituents at point-of-care settings has a potential for early diagnosis of ocular disorders such as dry eye disease, low-cost screening, and surveillance of at-risk subjects. However, current minimally-invasive rapid tear analysis systems for point-of-care settings have been limited to assessment of osmolarity or inflammatory markers and cannot differentiate between dry eye subclassifications. Here, we demonstrate a portable microfluidic system that allows quantitative analysis of electrolytes in the tear fluid that is suited for point-of-care settings. The microfluidic system consists of a capillary tube for sample collection, a reservoir for sample dilution, and a paper-based microfluidic device for electrolyte analysis. The sensing regions are functionalized with fluorescent crown ethers, o-acetanisidide, and seminaphtorhodafluor that are sensitive to mono- and divalent electrolytes, and their fluorescence outputs are measured with a smartphone readout device. The measured sensitivity values of Na(+), K(+), Ca(2+) ions and pH in artificial tear fluid were matched with the known ion concentrations within the physiological range. The microfluidic system was tested with samples having different ionic concentrations, demonstrating the feasibility for the detection of early-stage dry eye, differential diagnosis of dry eye sub-types, and their severity staging.

  17. Microfluidics-based laser cell-micropatterning system.

    PubMed

    Erdman, Nick; Schmidt, Lucas; Qin, Wan; Yang, Xiaoqi; Lin, Yongliang; DeSilva, Mauris N; Gao, Bruce Z

    2014-09-01

    The ability to place individual cells into an engineered microenvironment in a cell-culture model is critical for the study of in vivo relevant cell-cell and cell-extracellular matrix interactions. Microfluidics provides a high-throughput modality to inject various cell types into a microenvironment. Laser guided systems provide the high spatial and temporal resolution necessary for single-cell micropatterning. Combining these two techniques, the authors designed, constructed, tested and evaluated (1) a novel removable microfluidics-based cell-delivery biochip and (2) a combined system that uses the novel biochip coupled with a laser guided cell-micropatterning system to place individual cells into both two-dimensional (2D) and three-dimensional (3D) arrays. Cell-suspensions of chick forebrain neurons and glial cells were loaded into their respective inlet reservoirs and traversed the microfluidic channels until reaching the outlet ports. Individual cells were trapped and guided from the outlet of a microfluidic channel to a target site on the cell-culture substrate. At the target site, 2D and 3D pattern arrays were constructed with micron-level accuracy. Single-cell manipulation was accomplished at a rate of 150 μm s(-1) in the radial plane and 50 μm s(-1) in the axial direction of the laser beam. Results demonstrated that a single-cell can typically be patterned in 20-30 s, and that highly accurate and reproducible cellular arrays and systems can be achieved through coupling the microfluidics-based cell-delivery biochip with the laser guided system.

  18. Microfluidics-Based Laser Guided Cell-Micropatterning System

    PubMed Central

    Erdman, Nick; Schmidt, Lucas; Qin, Wan; Yang, Xiaoqi; Lin, Yongliang; DeSilva, Mauris N; Gao, Bruce Z.

    2014-01-01

    The ability to place individual cells into an engineered microenvironment in a cell-culture model is critical for the study of in vivo-relevant cell-cell and cell-extracellular matrix interactions. Microfluidics provides a high-throughput modality to inject various cell types into a microenvironment. Laser guided systems provide the high spatial and temporal resolution necessary for single-cell micropatterning. Combining these two techniques, the authors designed, constructed, tested, and evaluated 1) a novel removable microfluidics-based cell-delivery biochip and 2) a combined system that uses the novel biochip coupled with a laser guided cell-micropatterning system to place individual cells into both 2D and 3D arrays. Cell-suspensions of chick forebrain neurons and glial cells were loaded into their respective inlet reservoirs and traversed the microfluidic channels until reaching the outlet ports. Individual cells were trapped and guided from the outlet of a microfluidic channel to a target site on the cell-culture substrate. At the target site, 2D and 3D pattern arrays were constructed with micron-level accuracy. Single-cell manipulation was accomplished at a rate of 150 μm/s in the radial plane and 50 μm/s in the axial direction of the laser beam. Results demonstrated that a single-cell can typically be patterned in 20-30 seconds, and that highly accurate and reproducible cellular arrays and systems can be achieved through coupling the microfluidics-based cell-delivery biochip with the laser guided system. PMID:25190714

  19. [Advances on enzymes and enzyme inhibitors research based on microfluidic devices].

    PubMed

    Hou, Feng-Hua; Ye, Jian-Qing; Chen, Zuan-Guang; Cheng, Zhi-Yi

    2010-06-01

    With the continuous development in microfluidic fabrication technology, microfluidic analysis has evolved from a concept to one of research frontiers in last twenty years. The research of enzymes and enzyme inhibitors based on microfluidic devices has also made great progress. Microfluidic technology improved greatly the analytical performance of the research of enzymes and enzyme inhibitors by reducing the consumption of reagents, decreasing the analysis time, and developing automation. This review focuses on the development and classification of enzymes and enzyme inhibitors research based on microfluidic devices.

  20. Detection of heavy metal by paper-based microfluidics.

    PubMed

    Lin, Yang; Gritsenko, Dmitry; Feng, Shaolong; Teh, Yi Chen; Lu, Xiaonan; Xu, Jie

    2016-09-15

    Heavy metal pollution has shown great threat to the environment and public health worldwide. Current methods for the detection of heavy metals require expensive instrumentation and laborious operation, which can only be accomplished in centralized laboratories. Various microfluidic paper-based analytical devices have been developed recently as simple, cheap and disposable alternatives to conventional ones for on-site detection of heavy metals. In this review, we first summarize current development of paper-based analytical devices and discuss the selection of paper substrates, methods of device fabrication, and relevant theories in these devices. We then compare and categorize recent reports on detection of heavy metals using paper-based microfluidic devices on the basis of various detection mechanisms, such as colorimetric, fluorescent, and electrochemical methods. To finalize, the future development and trend in this field are discussed.

  1. Differential Ring Oscillator Based Capacitance Sensor for Microfluidic Applications.

    PubMed

    Mohammad, Kaveh; Thomson, Douglas J

    2017-04-01

    A simple high frequency capacitance sensor with 180 aF sensitivity is designed for a wide range of microfluidic applications. The sensor is implemented utilizing differential ring oscillators operating at [Formula: see text] MHz with a differential signal at [Formula: see text] MHz. The sensor occupies [Formula: see text] cm × 2 cm on a printed circuit board. The sensor is tuned using two precision variable capacitors and has a full scale range of [Formula: see text] pF. The sensor was able to detect less than 1% Isopropyl Alcohol in DI water and to detect 15 μm polystyrene spheres flowing over 25 μm lines and spaces coplanar electrodes in a microfluidic channel. The compact differential ring oscillator based architecture of the design makes it suitable to be integrated into microprocessor based systems for detection in Lab on Chip or Lab on Board applications.

  2. A frequency reconfigurable antenna based on digital microfluidics.

    PubMed

    Damgaci, Yasin; Cetiner, Bedri A

    2013-08-07

    We present a novel antenna reconfiguration mechanism relying on electrowetting based digital microfluidics to implement a frequency reconfigurable antenna operating in the X-band. The antenna built on a quartz substrate (εr = 3.9, tan δ = 0.0002) is a coplanar waveguide fed annular slot antenna, which is monolithically integrated with a microfluidic chip. This chip establishes an electrowetting on dielectric platform with a mercury droplet placed in it. The base contact area of the mercury droplet can be spread out by electrostatic actuation resulting in a change of loading capacitance. This in turn changes the resonant frequency of the antenna enabling a reversible reconfigurable impedance property. This reconfigurable antenna has been designed, fabricated and measured. The frequency of operation is tuned from around 11 GHz to 13 GHz as demonstrated by simulations and measurements. The design methodology, fabrication processes and the experimental results are given and discussed.

  3. Microfluidics for synthesis of peptide-based PET tracers.

    PubMed

    Liu, Yang; Tian, Mei; Zhang, Hong

    2013-01-01

    Positron emission tomography (PET) is a powerful noninvasive tool for acquisition of the physiological parameters in human and animals with the help of PET tracers. Among all the PET tracers, radiolabeled peptides have been widely explored for cancer-related receptor imaging due to their high affinity and specificity to receptors. But radiochemistry procedures for production of peptide-based PET tracers are usually complex, which makes large-scale clinical studies relatively challenging. New radiolabeling technologies which could simplify synthesis and purification procedures, are extremely needed. Over the last decade, microfluidics and lab-on-a-chip (LOC) technology have boomed as powerful tools in the field of organic chemistry, which potentially provide significant help to the PET chemistry. In this minireview, microfluidic radiolabeling technology is described and its application for synthesis of peptide-based PET tracers is summarized and discussed.

  4. Fine-tuning of magnetic and microfluidic viscous forces for specific magnetic bead-based immunocomplex formation

    NASA Astrophysics Data System (ADS)

    Cornaglia, M.; Tekin, H. C.; Lehnert, T.; Gijs, M. A. M.

    2013-08-01

    We investigate the working principle of a novel type of microfluidic sandwich immunoassay, as used for the detection of biomarkers. The heterogeneous assay is based on the specific interactions between an array of functionalized superparamagnetic beads and a flow of secondary superparamagnetic beads that carry the antigens and are simultaneously used as detection labels. We identify the main forces governing the immunoassay performance and develop a combined finite element method/analytical model to predict and control these forces. The clue for the improved assay specificity is in the fine-tuning of inter-bead magnetic dipolar and microfluidic viscous forces, which allows strongly reducing non-specific interactions, while enhancing the specific formation of immunocomplexes. We exploit our theoretical model to explain the enhanced sensitivity of magnetic bead-based immunoassay experiments performed in microfluidic chips.

  5. Uniform Yeast Cell Assembly Based on Microfluidic Microgels

    NASA Astrophysics Data System (ADS)

    Chang, Ya-Wen; He, Peng; Marquez, Manuel; Cheng, Zhengdong; Marquez, Samantha M.

    2011-03-01

    We present a novel microgel templated Yeastosome (Yeast- Celloidosome ) based on self-assembly of yeast cells onto liquid-gel interfaces. To organize living cells onto the surface of the gel particles, strong positive charges were first introduced via LbL (layer by layer) polyelectrolyte decoration on monodisperse agarose microgel templates fabricated with a microfluidic flow focusing device. Native yeasts, bearing negative surface charges can then be driven electrostatically to form a monolayer shell around the gel core. Surface coverage/packing density of the yeast biofilm on varying microgel-to-yeast size ratio assemblies is evaluated with optical microscopy. Mechanical properties of the corresponding shells are characterized with buckling or collapse behavior during drying-hydrating cycle. We demonstrate the capability to fabricate narrow size distribution Yeastosome with a soft hydrogel core. The combination of microfluidic fabrication with cell assembly offers excellent control over inner core properties and could enable further hierarchy bio-structures.

  6. Fabrication of paper-based microfluidic sensors by printing.

    PubMed

    Li, Xu; Tian, Junfei; Garnier, Gil; Shen, Wei

    2010-04-01

    A novel method for the fabrication of paper-based microfluidic diagnostic devices is reported; it consists of selectively hydrophobizing paper using cellulose reactive hydrophobization agents. The hydrophilic-hydrophobic contrast of patterns so created has excellent ability to control capillary penetration of aqueous liquids in paper channels. Incorporating this idea with digital ink jet printing techniques, a new fabrication method of paper-based microfluidic devices is established. Ink jet printing can deliver biomolecules and indicator reagents with precision into the microfluidic patterns to form bio-chemical sensing zones within the device. This method thus allows the complete sensor, i.e. channel patterns and the detecting chemistries, to be fabricated only by two printing steps. This fabrication method can be scaled up and adapted to use high speed, high volume and low cost commercial printing technology. Sensors can be fabricated for specific tests, or they can be made as general devices to perform on-demand quantitative analytical tasks by incorporating the required detection chemistries for the required tasks.

  7. Electrowetting-based actuation of droplets for integrated microfluidics.

    PubMed

    Pollack, M G; Shenderov, A D; Fair, R B

    2002-05-01

    The serviceability of microfluidics-based instrumentation including 'lab-on-a-chip' systems critically depends on control of fluid motion. We are reporting here an alternative approach to microfluidics based upon the micromanipulation of discrete droplets of aqueous electrolyte by electrowetting. Using a simple open structure, consisting of two sets of opposing planar electrodes fabricated on glass substrates, positional and formational control of microdroplets ranging in size from several nanoliters to several microliters has been demonstrated at voltages between 15-100 V. Since there are no permanent channels or structures between the plates, the system is highly flexible and reconfigurable. Droplet transport is rapid and efficient with average velocities exceeding 10 cm s(-1) having been observed. The dependence of the velocity on voltage is roughly independent of the droplet size within certain limits, thus the smallest droplets studied (approximately 3 nl) could be transported over 1000 times their length per second. Formation, mixing, and splitting of microdroplets was also demonstrated using the same microactuator structures. Thus, electrowetting provides a means to achieve high levels of functional integration and flexibility for microfluidic systems.

  8. Low-cost bioanalysis on paper-based and its hybrid microfluidic platforms.

    PubMed

    Dou, Maowei; Sanjay, Sharma Timilsina; Benhabib, Merwan; Xu, Feng; Li, XiuJun

    2015-12-01

    Low-cost assays have broad applications ranging from human health diagnostics and food safety inspection to environmental analysis. Hence, low-cost assays are especially attractive for rural areas and developing countries, where financial resources are limited. Recently, paper-based microfluidic devices have emerged as a low-cost platform which greatly accelerates the point of care (POC) analysis in low-resource settings. This paper reviews recent advances of low-cost bioanalysis on paper-based microfluidic platforms, including fully paper-based and paper hybrid microfluidic platforms. In this review paper, we first summarized the fabrication techniques of fully paper-based microfluidic platforms, followed with their applications in human health diagnostics and food safety analysis. Then we highlighted paper hybrid microfluidic platforms and their applications, because hybrid platforms could draw benefits from multiple device substrates. Finally, we discussed the current limitations and perspective trends of paper-based microfluidic platforms for low-cost assays.

  9. A microfluidic-based hydrodynamic trap for single particles.

    PubMed

    Johnson-Chavarria, Eric M; Tanyeri, Melikhan; Schroeder, Charles M

    2011-01-21

    The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in

  10. Quantum dot-based microfluidic biosensor for cancer detection

    NASA Astrophysics Data System (ADS)

    Ghrera, Aditya Sharma; Pandey, Chandra Mouli; Ali, Md. Azahar; Malhotra, Bansi Dhar

    2015-05-01

    We report results of the studies relating to fabrication of an impedimetric microfluidic-based nucleic acid sensor for quantification of DNA sequences specific to chronic myelogenous leukemia (CML). The sensor chip is prepared by patterning an indium-tin-oxide (ITO) coated glass substrate via wet chemical etching method followed by sealing with polydimethylsiloxane (PDMS) microchannel for fluid control. The fabricated microfluidic chip comprising of a patterned ITO substrate is modified by depositing cadmium selenide quantum dots (QCdSe) via Langmuir-Blodgett technique. Further, the QCdSe surface has been functionalized with specific DNA probe for CML detection. The probe DNA functionalized QCdSe integrated miniaturized system has been used to monitor target complementary DNA concentration by measuring the interfacial charge transfer resistance via hybridization. The presence of complementary DNA in buffer solution significantly results in decreased electro-conductivity of the interface due to presence of a charge barrier for transport of the redox probe ions. The microfluidic DNA biosensor exhibits improved linearity in the concentration range of 10-15 M to 10-11 M.

  11. Dissecting enzyme function with microfluidic-based deep mutational scanning

    PubMed Central

    Romero, Philip A.; Tran, Tuan M.; Abate, Adam R.

    2015-01-01

    Natural enzymes are incredibly proficient catalysts, but engineering them to have new or improved functions is challenging due to the complexity of how an enzyme’s sequence relates to its biochemical properties. Here, we present an ultrahigh-throughput method for mapping enzyme sequence–function relationships that combines droplet microfluidic screening with next-generation DNA sequencing. We apply our method to map the activity of millions of glycosidase sequence variants. Microfluidic-based deep mutational scanning provides a comprehensive and unbiased view of the enzyme function landscape. The mapping displays expected patterns of mutational tolerance and a strong correspondence to sequence variation within the enzyme family, but also reveals previously unreported sites that are crucial for glycosidase function. We modified the screening protocol to include a high-temperature incubation step, and the resulting thermotolerance landscape allowed the discovery of mutations that enhance enzyme thermostability. Droplet microfluidics provides a general platform for enzyme screening that, when combined with DNA-sequencing technologies, enables high-throughput mapping of enzyme sequence space. PMID:26040002

  12. Suspended microfluidics.

    PubMed

    Casavant, Benjamin P; Berthier, Erwin; Theberge, Ashleigh B; Berthier, Jean; Montanez-Sauri, Sara I; Bischel, Lauren L; Brakke, Kenneth; Hedman, Curtis J; Bushman, Wade; Keller, Nancy P; Beebe, David J

    2013-06-18

    Although the field of microfluidics has made significant progress in bringing new tools to address biological questions, the accessibility and adoption of microfluidics within the life sciences are still limited. Open microfluidic systems have the potential to lower the barriers to adoption, but the absence of robust design rules has hindered their use. Here, we present an open microfluidic platform, suspended microfluidics, that uses surface tension to fill and maintain a fluid in microscale structures devoid of a ceiling and floor. We developed a simple and ubiquitous model predicting fluid flow in suspended microfluidic systems and show that it encompasses many known capillary phenomena. Suspended microfluidics was used to create arrays of collagen membranes, mico Dots (μDots), in a horizontal plane separating two fluidic chambers, demonstrating a transwell platform able to discern collective or individual cellular invasion. Further, we demonstrated that μDots can also be used as a simple multiplexed 3D cellular growth platform. Using the μDot array, we probed the combined effects of soluble factors and matrix components, finding that laminin mitigates the growth suppression properties of the matrix metalloproteinase inhibitor GM6001. Based on the same fluidic principles, we created a suspended microfluidic metabolite extraction platform using a multilayer biphasic system that leverages the accessibility of open microchannels to retrieve steroids and other metabolites readily from cell culture. Suspended microfluidics brings the high degree of fluidic control and unique functionality of closed microfluidics into the highly accessible and robust platform of open microfluidics.

  13. DNA sequence analysis with droplet-based microfluidics

    PubMed Central

    Abate, Adam R.; Hung, Tony; Sperling, Ralph A.; Mary, Pascaline; Rotem, Assaf; Agresti, Jeremy J.; Weiner, Michael A.; Weitz, David A.

    2014-01-01

    Droplet-based microfluidic techniques can form and process micrometer scale droplets at thousands per second. Each droplet can house an individual biochemical reaction, allowing millions of reactions to be performed in minutes with small amounts of total reagent. This versatile approach has been used for engineering enzymes, quantifying concentrations of DNA in solution, and screening protein crystallization conditions. Here, we use it to read the sequences of DNA molecules with a FRET-based assay. Using probes of different sequences, we interrogate a target DNA molecule for polymorphisms. With a larger probe set, additional polymorphisms can be interrogated as well as targets of arbitrary sequence. PMID:24185402

  14. An integrated microfluidic biochemical detection system for protein analysis with magnetic bead-based sampling capabilities.

    PubMed

    Choi, Jin-Woo; Oh, Kwang W; Thomas, Jennifer H; Heineman, William R; Halsall, H Brian; Nevin, Joseph H; Helmicki, Arthur J; Henderson, H Thurman; Ahn, Chong H

    2002-02-01

    This paper presents the development and characterization of an integrated microfluidic biochemical detection system for fast and low-volume immunoassays using magnetic beads, which are used as both immobilization surfaces and bio-molecule carriers. Microfluidic components have been developed and integrated to construct a microfluidic biochemical detection system. Magnetic bead-based immunoassay, as a typical example of biochemical detection and analysis, has been successfully performed on the integrated microfluidic biochemical analysis system that includes a surface-mounted biofilter and electrochemical sensor on a glass microfluidic motherboard. Total time required for an immunoassay was less than 20 min including sample incubation time, and sample volume wasted was less than 50 microl during five repeated assays. Fast and low-volume biochemical analysis has been successfully achieved with the developed biofilter and immunosensor, which is integrated to the microfluidic system. Such a magnetic bead-based biochemical detection system, described in this paper, can be applied to protein analysis systems.

  15. Polydimethylsiloxane-based conducting composites and their applications in microfluidic chip fabrication

    PubMed Central

    Gong, Xiuqing; Wen, Weijia

    2009-01-01

    This paper reviews the design and fabrication of polydimethylsiloxane (PDMS)-based conducting composites and their applications in microfluidic chip fabrication. Owing to their good electrical conductivity and rubberlike elastic characteristics, these composites can be used variously in soft-touch electronic packaging, planar and three-dimensional electronic circuits, and in-chip electrodes. Several microfluidic components fabricated with PDMS-based composites have been introduced, including a microfluidic mixer, a microheater, a micropump, a microdroplet controller, as well as an all-in-one microfluidic chip. PMID:19693388

  16. A New Microfluidics-Based Droplet Dispenser for ICPMS

    PubMed Central

    2014-01-01

    In this work, a novel droplet microfluidic sample introduction system for inductively coupled plasma mass spectrometry (ICPMS) is proposed and characterized. The cheap and disposable microfluidic chip generates droplets of an aqueous sample in a stream of perfluorohexane (PFH), which is also used to eject them as a liquid jet. The aqueous droplets remain intact during the ejection and can be transported into the ICP with >50% efficiency. The transport is realized via a custom-built system, which includes a membrane desolvator necessary for the PFH vapor removal. The introduction system presented here can generate highly monodisperse droplets in the size range of 40–60 μm at frequencies from 90 to 300 Hz. These droplets produced very stable signals with a relative standard deviation (RSD) comparable to the one achieved with a commercial droplet dispenser. Using the current system, samples with a total volume of <1 μL can be analyzed. Moreover, the capabilities of the setup for introduction and quantitative elemental analysis of single cells were described using a test system of bovine red blood cells. In the future, other modules of the modern microfludics can be integrated in the chip, such as on-chip sample pretreatment or parallel introduction of different samples. PMID:24805360

  17. Fabric-based alkaline direct formate microfluidic fuel cells.

    PubMed

    Domalaon, Kryls; Tang, Catherine; Mendez, Alex; Bernal, Franky; Purohit, Krutarth; Pham, Linda; Haan, John; Gomez, Frank A

    2017-01-12

    Fabric-based microfluidic fuel cells (MFCs) serve as a novel, cost-efficient alternative to traditional FCs and batteries, since fluids naturally travel across fabric via capillary action, eliminating the need for an external pump and lowering production and operation costs. Building on previous research with Y-shaped paper-based MFCs, fabric-based MFCs mitigate fragility and durability issues caused by long periods of fuel immersion. In this study, we describe a microfluidic fabric-based direct formate fuel cell, with 5 M potassium formate and 30% hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using a two-strip, stacked design, the optimized parameters include the type of encasement, the barrier, and the fabric type. Surface contact of the fabric and laminate sheet expedited flow and respective chemical reactions. The maximum current (22.83 mA/cm(2) ) and power (4.40 mW/cm(2) ) densities achieved with a 65% cotton/35% polyester blend material are a respective 8.7% and 32% higher than previous studies with Y-shaped paper-based MFCs. In series configuration, the MFCs generate sufficient energy to power a handheld calculator, a thermometer, and a spectrum of light-emitting diodes.

  18. Lossless droplet transfer of droplet-based microfluidic analysis

    SciTech Connect

    Kelly, Ryan T; Tang, Keqi; Page, Jason S; Smith, Richard D

    2011-11-22

    A transfer structure for droplet-based microfluidic analysis is characterized by a first conduit containing a first stream having at least one immiscible droplet of aqueous material and a second conduit containing a second stream comprising an aqueous fluid. The interface between the first conduit and the second conduit can define a plurality of apertures, wherein the apertures are sized to prevent exchange of the first and second streams between conduits while allowing lossless transfer of droplets from the first conduit to the second conduit through contact between the first and second streams.

  19. Microfluidic electronics.

    PubMed

    Cheng, Shi; Wu, Zhigang

    2012-08-21

    Microfluidics, a field that has been well-established for several decades, has seen extensive applications in the areas of biology, chemistry, and medicine. However, it might be very hard to imagine how such soft microfluidic devices would be used in other areas, such as electronics, in which stiff, solid metals, insulators, and semiconductors have previously dominated. Very recently, things have radically changed. Taking advantage of native properties of microfluidics, advances in microfluidics-based electronics have shown great potential in numerous new appealing applications, e.g. bio-inspired devices, body-worn healthcare and medical sensing systems, and ergonomic units, in which conventional rigid, bulky electronics are facing insurmountable obstacles to fulfil the demand on comfortable user experience. Not only would the birth of microfluidic electronics contribute to both the microfluidics and electronics fields, but it may also shape the future of our daily life. Nevertheless, microfluidic electronics are still at a very early stage, and significant efforts in research and development are needed to advance this emerging field. The intention of this article is to review recent research outcomes in the field of microfluidic electronics, and address current technical challenges and issues. The outlook of future development in microfluidic electronic devices and systems, as well as new fabrication techniques, is also discussed. Moreover, the authors would like to inspire both the microfluidics and electronics communities to further exploit this newly-established field.

  20. Microfluidic chip-based analytical system for rapid screening of photocatalysts.

    PubMed

    Zhang, Hao; Wang, Jing-Jing; Fan, Jie; Fang, Qun

    2013-11-15

    A simple and efficient microfluidic chip-based analytical system for rapid screening of photocatalysts was developed. The catalyst screening system consisted of a microchip with multiple channels for parallel reactions, a UV light source, and a CCD camera-based photometric detection system for monitoring the photocatalytic reaction. A novel microfluidic introduction method for loading particle samples into chip microchannels was established using dry sample powders and wedge-structure channel design. With this method, multiple different photocatalyst samples could be quickly introduced into the microchip with good reproducibility without the need of additional pumps or valves. We applied the present system in the rapid screening of doping TiO2 photocatalysts in terms of their activity for methylene blue (MB) degradation under UV light irradiation. Ten parallel photocatalyst screening reactions were achieved within 15 min in the multi-channel chip. We also examined nine element doped TiO2 materials to investigate the doping effects of different elements on TiO2. Compared with conventional systems, the photocatalyst consumption (0.1mg) in the present system was significantly reduced at least 100 times. High reaction rate in chip microreactors was obtained with an increase of two orders of magnitude over bulk reactors. The miniaturization of the photocatalytic reaction on the microchip significantly improves the reaction rates, reduces the sample and reagent consumptions, and increases the throughput of screening for multiple catalyst samples in parallel. The present work provides a novel application for microfluidic chip-based analytical systems, as well as a rapid, highly-efficient and low-consumption method for screening of photocatalysts.

  1. Magnetophoretic-based microfluidic device for DNA Concentration.

    PubMed

    Shim, Sangjo; Shim, Jiwook; Taylor, William R; Kosari, Farhad; Vasmatzis, George; Ahlquist, David A; Bashir, Rashid

    2016-04-01

    Nucleic acids serve as biomarkers of disease and it is highly desirable to develop approaches to extract small number of such genomic extracts from human bodily fluids. Magnetic particles-based nucleic acid extraction is widely used for concentration of small amount of samples and is followed by DNA amplification in specific assays. However, approaches to integrate such magnetic particles based capture with micro and nanofluidic based assays are still lacking. In this report, we demonstrate a magnetophoretic-based approach for target-specific DNA extraction and concentration within a microfluidic device. This device features a large chamber for reducing flow velocity and an array of μ-magnets for enhancing magnetic flux density. With this strategy, the device is able to collect up to 95 % of the magnetic particles from the fluidic flow and to concentrate these magnetic particles in a collection region. Then an enzymatic reaction is used to detach the DNA from the magnetic particles within the microfluidic device, making the DNA available for subsequent analysis. Concentrations of over 1000-fold for 90 bp dsDNA molecules is demonstrated. This strategy can bridge the gap between detection of low concentration analytes from clinical samples and a range of micro and nanofluidic sensors and devices including nanopores, nano-cantilevers, and nanowires.

  2. Lab-chip HPLC with integrated droplet-based microfluidics for separation and high frequency compartmentalisation.

    PubMed

    Kim, Jin-Young; Cho, Soong-Won; Kang, Dong-Ku; Edel, Joshua B; Chang, Soo-Ik; deMello, Andrew J; O'Hare, Danny

    2012-09-21

    We demonstrate the integration of a droplet-based microfluidic device with high performance liquid chromatography (HPLC) in a monolithic format. Sequential operations of separation, compartmentalisation and concentration counter were conducted on a monolithic chip. This describes the use of droplet-based microfluidics for the preservation of chromatographic separations, and its potential application as a high frequency fraction collector.

  3. Microfluidic-Based sample chips for radioactive solutions

    SciTech Connect

    Tripp, J. L.; Law, J. D.; Smith, T. E.; Rutledge, V. J.; Bauer, W. F.; Ball, R. D.; Hahn, P. A.

    2015-01-01

    Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument would greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.

  4. Microfluidic-Based Sample Chips for Radioactive Solutions

    SciTech Connect

    Tripp, J. L.; Law, J. D.; Smith, T. E.; Rutledge, V. J.; Bauer, W. F.; Ball, R. D.; Hahn, P. A.

    2014-02-01

    Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument would greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.

  5. Nanomaterial based detection and degradation of biological and chemical contaminants in a microfluidic system

    NASA Astrophysics Data System (ADS)

    Jayamohan, Harikrishnan

    fabricated using non-cleanroom-based methods, making it suitable for economical large-scale manufacture. A computational model of the microfluidic format was developed in COMSOL MultiphysicsRTM finite element software to evaluate the effect of diffusion coefficient and rate constant on the photocatalytic performance. To further enhance the photocatalytic performance of the microfluidic device, TNA synthesized on a mesh was used as the catalyst. The new system was shown to have enhanced photocatalytic performance in comparison to TNA on a foil. The device was then employed in the inactivation of E. coli O157:H7 at different flow rates and light intensities (100, 50, 20, 10 mW/cm2). In the second project, a protocol for ultra-sensitive indirect electrochemical detection of E. coli O157:H7 was reported. The protocol uses antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized secondary (polystyrene) beads as an electrochemical tag. The method was able to detect concentrations of E. coli O157:H7 down to 3 CFU/100 mL (S/N=3). We also demonstrate the use of the protocol for detection of E. coli O157:H7 seeded in wastewater effluent samples.

  6. Microfluidics based phantoms of superficial vascular network

    PubMed Central

    Luu, Long; Roman, Patrick A.; Mathews, Scott A.; Ramella-Roman, Jessica C.

    2012-01-01

    Several new bio-photonic techniques aim to measure flow in the human vasculature non-destructively. Some of these tools, such as laser speckle imaging or Doppler optical coherence tomography, are now reaching the clinical stage. Therefore appropriate calibration and validation techniques dedicated to these particular measurements are therefore of paramount importance. In this paper we introduce a fast prototyping technique based on laser micromachining for the fabrication of dynamic flow phantoms. Micro-channels smaller than 20 µm in width can be formed in a variety of materials such as epoxies, plastics, and household tape. Vasculature geometries can be easily and quickly modified to accommodate a particular experimental scenario. PMID:22741081

  7. PDMS based microfluidic chips and their application in material synthesis

    NASA Astrophysics Data System (ADS)

    Gong, Xiuqing

    Microfluidics is a highly interdisciplinary science which is to deal with the behavior, control and manipulation of fluids that are constrained to sub-milimeter scale. It incorporates the knowledge and technique intersecting physics, chemistry, mechanics, nanoscience and biotechnology, with practical applications to the design of systems in which small volumes of fluids will be used. In this thesis, we started our research from GER fluid synthesis which then is applied to designing different functions of microfluidic devices, valve, pump, and mixer. We built a way to correlate mechanical signal with electric signal by soft matter. The mechanical devices based GER fluid had good operating stability and mechanical performance. We studied how to improve the performance of GER fluid by increasing the yield stress while avoiding the sendimentation of nanoparticles in GER suspension. The meaning of this work is to enhance the stability and mechanical strength of GER fluid when it is applyed to the microfluidc channels. We tried different oils and studied the particle size for the GER effect. The largest yield stress which amounts to 300 kPa is achievable compared to previous GER fluid with 100 kPa. Microfluidic reactor, directing the flow of microliter volumes along microscale channels, offers the advantages of precise control of reagent loading, fast mixing and an enhanced reaction rate, cessation of the reaction at specific stages, and more. Basically, there are two microfluidic flow regimes, continuous flow and segmented flow (suspended droplets, channel-spanning slug, and wall-wetting films). Both flow regimes offer chemical reaction applications, e.g., continuous flow formation of polymer nanospheres and inorganic nanoparticles, size- and shape-control synthesis by segmented flow, and precipitate-forming reactions in droplets, wherein the segmented flow has gained more popularity in that area. The compartmentalization of segmented flow offers advantages to chemical

  8. Droplet-based microfluidics and the dynamics of emulsions

    NASA Astrophysics Data System (ADS)

    Baret, Jean-Christophe; Brosseau, Quentin; Semin, Benoit; Qu, Xiaopeng

    2012-02-01

    Emulsions are complex fluids already involved for a long time in a wide-range of industrial processes, such as, for example, food, cosmetics or materials synthesis [1]. More recently, applications of emulsions have been extended to new fields like biotechnology or biochemistry where the compartmentalization of compounds in emulsion droplets is used to parallelise (bio-) chemical reactions [2]. Interestingly, these applications pinpoint to fundamental questions dealing with surfactant dynamics, dynamic surface tension, hydrodynamic interactions and electrohydrodynamics. Droplet-based microfluidics is a very powerful tool to quantitatively study the dynamics of emulsions at the single droplet level or even at the single interface level: well-controlled emulsions are produced and manipulated using hydrodynamics, electrical forces, optical actuation and combination of these effects. We will describe here how droplet-based microfluidics is used to extract quantitative informations on the physical-chemistry of emulsions for a better understanding and control of the dynamics of these systems [3].[4pt] [1] J. Bibette et al. Rep. Prog. Phys., 62, 969-1033 (1999)[0pt] [2] A. Theberge et al., Angewandte Chemie Int. Ed. 49, 5846 (2010)[0pt] [3] J.-C. Baret et al., Langmuir, 25, 6088 (2009)

  9. A perspective on paper-based microfluidics: Current status and future trends.

    PubMed

    Li, Xu; Ballerini, David R; Shen, Wei

    2012-03-01

    "Paper-based microfluidics" or "lab on paper," as a burgeoning research field with its beginning in 2007, provides a novel system for fluid handling and fluid analysis for a variety of applications including health diagnostics, environmental monitoring as well as food quality testing. The reasons why paper becomes an attractive substrate for making microfluidic systems include: (1) it is a ubiquitous and extremely cheap cellulosic material; (2) it is compatible with many chemical/biochemical/medical applications; and (3) it transports liquids using capillary forces without the assistance of external forces. By building microfluidic channels on paper, liquid flow is confined within the channels, and therefore, liquid flow can be guided in a controlled manner. A variety of 2D and even 3D microfluidic channels have been created on paper, which are able to transport liquids in the predesigned pathways on paper. At the current stage of its development, paper-based microfluidic system is claimed to be low-cost, easy-to-use, disposable, and equipment-free, and therefore, is a rising technology particularly relevant to improving the healthcare and disease screening in the developing world, especially for those areas with no- or low-infrastructure and limited trained medical and health professionals. The research in paper-based microfluidics is experiencing a period of explosion; most published works have focused on: (1) inventing low-cost and simple fabrication techniques for paper-based microfluidic devices; and (2) exploring new applications of paper-based microfluidics by incorporating efficient detection methods. This paper aims to review both the fabrication techniques and applications of paper-based microfluidics reported to date. This paper also attempts to convey to the readers, from the authors' point of view the current limitations of paper-based microfluidics which require further research, and a few perspective directions this new analytical system may take in

  10. Investigation of bacterial chemotaxis in flow-based microfluidic devices.

    PubMed

    Englert, Derek L; Manson, Michael D; Jayaraman, Arul

    2010-05-01

    The plug-in-pond and capillary assays are convenient methods for measuring attractant and repellent bacterial chemotaxis. However, these assays do not provide quantitative information on the extent of migration and are not well-suited for investigating repellent taxis. Here, we describe a protocol for a flow-based microfluidic system (microFlow) to quantitatively investigate chemotaxis in response to concentration gradients of attractants and repellents. The microFlow device uses diffusive mixing to generate concentration gradients that are stable throughout the chemotaxis chamber and for the duration of the experiment. The gradients may be of any desired absolute concentration and gradient strength. GFP-expressing bacteria immediately encounter a stable concentration gradient when they enter the chemotaxis chamber, and the migration in response to the gradient is monitored by microscopy. The effects of different parameters that influence the extent of migration in the microFlow device-preparation of the motile bacterial population preparation, strength of the concentration gradient and duration of exposure to the gradient-are discussed in the context of repellent taxis of chemotactically wild-type Escherichia coli cells in a gradient of NiSO(4). Fabrication of the microfluidic device takes 1 d while preparing motile cells and carrying out the chemotaxis experiment takes 4-6 h to complete.

  11. Quantum dot-based microfluidic biosensor for cancer detection

    SciTech Connect

    Ghrera, Aditya Sharma; Pandey, Chandra Mouli; Ali, Md. Azahar; Malhotra, Bansi Dhar

    2015-05-11

    We report results of the studies relating to fabrication of an impedimetric microfluidic–based nucleic acid sensor for quantification of DNA sequences specific to chronic myelogenous leukemia (CML). The sensor chip is prepared by patterning an indium–tin–oxide (ITO) coated glass substrate via wet chemical etching method followed by sealing with polydimethylsiloxane (PDMS) microchannel for fluid control. The fabricated microfluidic chip comprising of a patterned ITO substrate is modified by depositing cadmium selenide quantum dots (QCdSe) via Langmuir–Blodgett technique. Further, the QCdSe surface has been functionalized with specific DNA probe for CML detection. The probe DNA functionalized QCdSe integrated miniaturized system has been used to monitor target complementary DNA concentration by measuring the interfacial charge transfer resistance via hybridization. The presence of complementary DNA in buffer solution significantly results in decreased electro-conductivity of the interface due to presence of a charge barrier for transport of the redox probe ions. The microfluidic DNA biosensor exhibits improved linearity in the concentration range of 10{sup −15} M to 10{sup −11} M.

  12. Flow-based analysis using microfluidics-chemiluminescence systems.

    PubMed

    Al Lawati, Haider A J

    2013-01-01

    This review will discuss various approaches and techniques in which analysis using microfluidics-chemiluminescence systems (MF-CL) has been reported. A variety of applications is examined, including environmental, pharmaceutical, biological, food and herbal analysis. Reported uses of CL reagents, sample introduction techniques, sample pretreatment methods, CL signal enhancement and detection systems are discussed. A hydrodynamic pumping system is predominately used for these applications. However, several reports are available in which electro-osmotic (EO) pumping has been implemented. Various sample pretreatment methods have been used, including liquid-liquid extraction, solid-phase extraction and molecularly imprinted polymers. A wide range of innovative techniques has been reported for CL signal enhancement. Most of these techniques are based on enhancement of the mixing process in the microfluidics channels, which leads to enhancement of the CL signal. However, other techniques are also reported, such as mirror reaction, liquid core waveguide, on-line pre-derivatization and the use of an opaque white chip with a thin transparent seal. Photodetectors are the most commonly used detectors; however, other detection systems have also been used, including integrated electrochemiluminescence (ECL) and organic photodiodes (OPDs).

  13. Microfluidic immunoassays as rapid saliva-based clinical diagnostics

    PubMed Central

    Herr, Amy E.; Hatch, Anson V.; Throckmorton, Daniel J.; Tran, Huu M.; Brennan, James S.; Giannobile, William V.; Singh, Anup K.

    2007-01-01

    At present, point-of-care (POC) diagnostics typically provide a binary indication of health status (e.g., home pregnancy test strip). Before anticipatory use of diagnostics for assessment of complex diseases becomes widespread, development of sophisticated bioassays capable of quantitatively measuring disease biomarkers is necessary. Successful translation of new bioassays into clinical settings demands the ability to monitor both the onset and progression of disease. Here we report on a clinical POC diagnostic that enables rapid quantitation of an oral disease biomarker in human saliva by using a monolithic disposable cartridge designed to operate in a compact analytical instrument. Our microfluidic method facilitates hands-free saliva analysis by integrating sample pretreatment (filtering, enrichment, mixing) with electrophoretic immunoassays to quickly measure analyte concentrations in minimally pretreated saliva samples. Using 20 μl of saliva, we demonstrate rapid (<10 min) measurement of the collagen-cleaving enzyme matrix metalloproteinase-8 (MMP-8) in saliva from healthy and periodontally diseased subjects. In addition to physiologically measurable indicators of periodontal disease, conventional measurements of salivary MMP-8 were used to validate the microfluidic assays described in this proof-of-principle study. The microchip-based POC diagnostic demonstrated is applicable to rapid, reliable measurement of proteinaceous disease biomarkers in biological fluids. PMID:17374724

  14. Microfluidic immunoassays as rapid saliva-based clinical diagnostics.

    PubMed

    Herr, Amy E; Hatch, Anson V; Throckmorton, Daniel J; Tran, Huu M; Brennan, James S; Giannobile, William V; Singh, Anup K

    2007-03-27

    At present, point-of-care (POC) diagnostics typically provide a binary indication of health status (e.g., home pregnancy test strip). Before anticipatory use of diagnostics for assessment of complex diseases becomes widespread, development of sophisticated bioassays capable of quantitatively measuring disease biomarkers is necessary. Successful translation of new bioassays into clinical settings demands the ability to monitor both the onset and progression of disease. Here we report on a clinical POC diagnostic that enables rapid quantitation of an oral disease biomarker in human saliva by using a monolithic disposable cartridge designed to operate in a compact analytical instrument. Our microfluidic method facilitates hands-free saliva analysis by integrating sample pretreatment (filtering, enrichment, mixing) with electrophoretic immunoassays to quickly measure analyte concentrations in minimally pretreated saliva samples. Using 20 microl of saliva, we demonstrate rapid (<10 min) measurement of the collagen-cleaving enzyme matrix metalloproteinase-8 (MMP-8) in saliva from healthy and periodontally diseased subjects. In addition to physiologically measurable indicators of periodontal disease, conventional measurements of salivary MMP-8 were used to validate the microfluidic assays described in this proof-of-principle study. The microchip-based POC diagnostic demonstrated is applicable to rapid, reliable measurement of proteinaceous disease biomarkers in biological fluids.

  15. Toner and paper-based fabrication techniques for microfluidic applications.

    PubMed

    Coltro, Wendell Karlos Tomazelli; de Jesus, Dosil Pereira; da Silva, José Alberto Fracassi; do Lago, Claudimir Lucio; Carrilho, Emanuel

    2010-08-01

    The interest in low-cost microfluidic platforms as well as emerging microfabrication techniques has increased considerably over the last years. Toner- and paper-based techniques have appeared as two of the most promising platforms for the production of disposable devices for on-chip applications. This review focuses on recent advances in the fabrication techniques and in the analytical/bioanalytical applications of toner and paper-based devices. The discussion is divided in two parts dealing with (i) toner and (ii) paper devices. Examples of miniaturized devices fabricated by using direct-printing or toner transfer masking in polyester-toner, glass, PDMS as well as conductive platforms as recordable compact disks and printed circuit board are presented. The construction and the use of paper-based devices for off-site diagnosis and bioassays are also described to cover this emerging platform for low-cost diagnostics.

  16. An investigation of paper based microfluidic devices for size based separation and extraction applications.

    PubMed

    Zhong, Z W; Wu, R G; Wang, Z P; Tan, H L

    2015-09-01

    Conventional microfluidic devices are typically complex and expensive. The devices require the use of pneumatic control systems or highly precise pumps to control the flow in the devices. This work investigates an alternative method using paper based microfluidic devices to replace conventional microfluidic devices. Size based separation and extraction experiments conducted were able to separate free dye from a mixed protein and dye solution. Experimental results showed that pure fluorescein isothiocyanate could be separated from a solution of mixed fluorescein isothiocyanate and fluorescein isothiocyanate labeled bovine serum albumin. The analysis readings obtained from a spectrophotometer clearly show that the extracted tartrazine sample did not contain any amount of Blue-BSA, because its absorbance value was 0.000 measured at a wavelength of 590nm, which correlated to Blue-BSA. These demonstrate that paper based microfluidic devices, which are inexpensive and easy to implement, can potentially replace their conventional counterparts by the use of simple geometry designs and the capillary action. These findings will potentially help in future developments of paper based microfluidic devices.

  17. Spatial Chemical Stimulation Control in Microenvironment by Microfluidic Probe Integrated Device for Cell-Based Assay

    PubMed Central

    Horayama, Masayuki; Shinha, Kenta; Kabayama, Kazuya; Fujii, Teruo

    2016-01-01

    Cell—cell interactions play an important role in the development and function of multicellular organisms. To investigate these interactions in detail, it is necessary to evaluate the behavior of a cell population when the minimum number of cells in the population is stimulated by some chemical factors. We propose a microfluidic device integrated with microfluidic probe (MFP) functionality; this device is capable of imparting a chemical stimulus to cells within a microenvironment, for cell-based assays. The device contains MFP channels at the walls of the cell culture microchannels, and it can control a localized chemical stimulation area at the scale of a single cell to a few cells using MFP fluid control in a microspace. The results of a finite element method-based simulation indicated that it is possible to control the chemical stimulation area at the scale of a single cell to a few cells by optimizing the MFP channel apex width and the flow ratio. In addition, localized cell staining was demonstrated successfully using a spatial chemical stimulus. We confirmed the device functionality as a novel cell-based assay tool. We succeeded in performing localized cell collection using this method, which suggested that the single cell analysis of a cell monolayer that is subjected to a specific chemical stimulus is possible. The method proposed in this paper can contribute significantly to the fields of cell biology and drug development. PMID:27930750

  18. Microfluidic droplet-based liquid-liquid extraction: online model validation.

    PubMed

    Lubej, Martin; Novak, Uroš; Liu, Mingqiang; Martelanc, Mitja; Franko, Mladen; Plazl, Igor

    2015-05-21

    Droplet-based liquid-liquid extraction in a microchannel was studied, both theoretically and experimentally. A full 3D mathematical model, incorporating convection and diffusion in all spatial directions along with the velocity profile, was developed to depict the governing transport characteristics of droplet-based microfluidics. The finite elements method, as the most common macroscale simulation technique, was used to solve the set of differential equations regarding conservation of moment, mass and solute concentration in a two-domain system coupled by interfacial surface of droplet-based flow pattern. The model was numerically verified and validated online by following the concentrations of a solute in two phases within the microchannel. The relative azobenzene concentration profiles in a methanol/n-octane two-phase system at different positions along the channel length were retrieved by means of a thermal lens microscopic (TLM) technique coupled to a microfluidic system, which gave results of high spatial and temporal resolution. Very good agreement between model calculations and online experimental data was achieved without applying any fitting procedure to the model parameters.

  19. Electrochemiluminescence detection in microfluidic cloth-based analytical devices.

    PubMed

    Guan, Wenrong; Liu, Min; Zhang, Chunsun

    2016-01-15

    This work describes the first approach at combining microfluidic cloth-based analytical devices (μCADs) with electrochemiluminescence (ECL) detection. Wax screen-printing is employed to make cloth-based microfluidic chambers which are patterned with carbon screen-printed electrodes (SPEs) to create truly disposable, simple, inexpensive sensors which can be read with a low-cost, portable charge coupled device (CCD) imaging sensing system. And, the two most commonly used ECL systems of tris(2,2'-bipyridyl)ruthenium(II)/tri-n-propylamine (Ru(bpy)3(2+)/TPA) and 3-aminophthalhydrazide/hydrogen peroxide (luminol/H2O2) are applied to demonstrate the quantitative ability of the ECL μCADs. In this study, the proposed devices have successfully fulfilled the determination of TPA with a linear range from 2.5 to 2500μM with a detection limit of 1.265μM. In addition, the detection of H2O2 can be performed in the linear range of 0.05-2.0mM, with a detection limit of 0.027mM. It has been shown that the ECL emission on the wax-patterned cloth device has an acceptable sensitivity, stability and reproducibility. Finally, the applicability of cloth-based ECL is demonstrated for determination of glucose in phosphate buffer solution (PBS) and artificial urine (AU) samples, with the detection limits of 0.032mM and 0.038mM, respectively. It can be foreseen, therefore, that μCADs with ECL detection could provide a new sensing platform for point-of-care testing, public health, food safety detection and environmental monitoring in remote regions, developing or developed countries.

  20. Microprocessor-based integration of microfluidic control for the implementation of automated sensor monitoring and multithreaded optimization algorithms.

    PubMed

    Ezra, Elishai; Maor, Idan; Bavli, Danny; Shalom, Itai; Levy, Gahl; Prill, Sebastian; Jaeger, Magnus S; Nahmias, Yaakov

    2015-08-01

    Microfluidic applications range from combinatorial synthesis to high throughput screening, with platforms integrating analog perfusion components, digitally controlled micro-valves and a range of sensors that demand a variety of communication protocols. Currently, discrete control units are used to regulate and monitor each component, resulting in scattered control interfaces that limit data integration and synchronization. Here, we present a microprocessor-based control unit, utilizing the MS Gadgeteer open framework that integrates all aspects of microfluidics through a high-current electronic circuit that supports and synchronizes digital and analog signals for perfusion components, pressure elements, and arbitrary sensor communication protocols using a plug-and-play interface. The control unit supports an integrated touch screen and TCP/IP interface that provides local and remote control of flow and data acquisition. To establish the ability of our control unit to integrate and synchronize complex microfluidic circuits we developed an equi-pressure combinatorial mixer. We demonstrate the generation of complex perfusion sequences, allowing the automated sampling, washing, and calibrating of an electrochemical lactate sensor continuously monitoring hepatocyte viability following exposure to the pesticide rotenone. Importantly, integration of an optical sensor allowed us to implement automated optimization protocols that require different computational challenges including: prioritized data structures in a genetic algorithm, distributed computational efforts in multiple-hill climbing searches and real-time realization of probabilistic models in simulated annealing. Our system offers a comprehensive solution for establishing optimization protocols and perfusion sequences in complex microfluidic circuits.

  1. Exploration of microfluidic devices based on multi-filament threads and textiles: A review

    PubMed Central

    Nilghaz, A.; Ballerini, D. R.; Shen, W.

    2013-01-01

    In this paper, we review the recent progress in the development of low-cost microfluidic devices based on multifilament threads and textiles for semi-quantitative diagnostic and environmental assays. Hydrophilic multifilament threads are capable of transporting aqueous and non-aqueous fluids via capillary action and possess desirable properties for building fluid transport pathways in microfluidic devices. Thread can be sewn onto various support materials to form fluid transport channels without the need for the patterned hydrophobic barriers essential for paper-based microfluidic devices. Thread can also be used to manufacture fabrics which can be patterned to achieve suitable hydrophilic-hydrophobic contrast, creating hydrophilic channels which allow the control of fluids flow. Furthermore, well established textile patterning methods and combination of hydrophilic and hydrophobic threads can be applied to fabricate low-cost microfluidic devices that meet the low-cost and low-volume requirements. In this paper, we review the current limitations and shortcomings of multifilament thread and textile-based microfluidics, and the research efforts to date on the development of fluid flow control concepts and fabrication methods. We also present a summary of different methods for modelling the fluid capillary flow in microfluidic thread and textile-based systems. Finally, we summarized the published works of thread surface treatment methods and the potential of combining multifilament thread with other materials to construct devices with greater functionality. We believe these will be important research focuses of thread- and textile-based microfluidics in future. PMID:24086179

  2. A self assembled monolayer based microfluidic sensor for urea detection

    NASA Astrophysics Data System (ADS)

    Srivastava, Saurabh; Solanki, Pratima R.; Kaushik, Ajeet; Ali, Md. Azahar; Srivastava, Anchal; Malhotra, B. D.

    2011-07-01

    Urease (Urs) and glutamate dehydrogenase (GLDH) have been covalently co-immobilized onto a self-assembled monolayer (SAM) comprising of 10-carboxy-1-decanthiol (CDT) via EDC-NHS chemistry deposited onto one of the two patterned gold (Au) electrodes for estimation of urea using poly(dimethylsiloxane) based microfluidic channels (2 cm × 200 μm × 200 μm). The CDT/Au and Urs-GLDH/CDT/Au electrodes have been characterized using Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), atomic force microscopy (AFM) and electrochemical cyclic voltammetry (CV) techniques. The electrochemical response measurement of a Urs-GLDH/CDT/Au bioelectrode obtained as a function of urea concentration using CV yield linearity as 10 to 100 mg dl-1, detection limit as 9 mg dl-1 and high sensitivity as 7.5 μA mM-1 cm-2.

  3. Surface geometry based hydrophobicity of the PDMS for microfluidic devices

    NASA Astrophysics Data System (ADS)

    Pelayo, J. C.; Badiola, R. A.; Castañares, J.; Pili, U.; Violanda, R.; Bacabac, R.

    2015-06-01

    In this report, the surface hydrophobicity of PDMS was investigated using two methods of preparations. The first method was performed by changing the surface roughness through the use of different molds. The second method was performed by varying the reconstitution ratio (volume of elastomer base to volume of elastomer curing) of the PDMS. Variation in the hydrophobicity of the PDMS was characterized by measuring the contact angle of a liquid droplet against the surface of the PDMS. The results showed that both the surface roughness and the reconstitution ratio of the PDMS positively correlated with the contact angle measured regardless of the liquid used. The maximum and minimum contact angle obtained were θr = (138 ± 3)° and θr = (99 ± 3)°, respectively. The results demonstrate a straightforward way of fabricating microfluidic devices using PDMS with controlled hydrophobicity.

  4. Genetic interaction mapping with microfluidic-based single cell sequencing

    PubMed Central

    Haliburton, John R.; Shao, Wenjun; Deutschbauer, Adam; Arkin, Adam; Abate, Adam R.

    2017-01-01

    Genetic interaction mapping is useful for understanding the molecular basis of cellular decision making, but elucidating interactions genome-wide is challenging due to the massive number of gene combinations that must be tested. Here, we demonstrate a simple approach to thoroughly map genetic interactions in bacteria using microfluidic-based single cell sequencing. Using single cell PCR in droplets, we link distinct genetic information into single DNA sequences that can be decoded by next generation sequencing. Our approach is scalable and theoretically enables the pooling of entire interaction libraries to interrogate multiple pairwise genetic interactions in a single culture. The speed, ease, and low-cost of our approach makes genetic interaction mapping viable for routine characterization, allowing the interaction network to be used as a universal read out for a variety of biology experiments, and for the elucidation of interaction networks in non-model organisms. PMID:28170417

  5. Genetic interaction mapping with microfluidic-based single cell sequencing.

    PubMed

    Haliburton, John R; Shao, Wenjun; Deutschbauer, Adam; Arkin, Adam; Abate, Adam R

    2017-01-01

    Genetic interaction mapping is useful for understanding the molecular basis of cellular decision making, but elucidating interactions genome-wide is challenging due to the massive number of gene combinations that must be tested. Here, we demonstrate a simple approach to thoroughly map genetic interactions in bacteria using microfluidic-based single cell sequencing. Using single cell PCR in droplets, we link distinct genetic information into single DNA sequences that can be decoded by next generation sequencing. Our approach is scalable and theoretically enables the pooling of entire interaction libraries to interrogate multiple pairwise genetic interactions in a single culture. The speed, ease, and low-cost of our approach makes genetic interaction mapping viable for routine characterization, allowing the interaction network to be used as a universal read out for a variety of biology experiments, and for the elucidation of interaction networks in non-model organisms.

  6. A perspective on paper-based microfluidics: Current status and future trends

    PubMed Central

    Li, Xu; Ballerini, David R.; Shen, Wei

    2012-01-01

    “Paper-based microfluidics” or “lab on paper,” as a burgeoning research field with its beginning in 2007, provides a novel system for fluid handling and fluid analysis for a variety of applications including health diagnostics, environmental monitoring as well as food quality testing. The reasons why paper becomes an attractive substrate for making microfluidic systems include: (1) it is a ubiquitous and extremely cheap cellulosic material; (2) it is compatible with many chemical/biochemical/medical applications; and (3) it transports liquids using capillary forces without the assistance of external forces. By building microfluidic channels on paper, liquid flow is confined within the channels, and therefore, liquid flow can be guided in a controlled manner. A variety of 2D and even 3D microfluidic channels have been created on paper, which are able to transport liquids in the predesigned pathways on paper. At the current stage of its development, paper-based microfluidic system is claimed to be low-cost, easy-to-use, disposable, and equipment-free, and therefore, is a rising technology particularly relevant to improving the healthcare and disease screening in the developing world, especially for those areas with no- or low-infrastructure and limited trained medical and health professionals. The research in paper-based microfluidics is experiencing a period of explosion; most published works have focused on: (1) inventing low-cost and simple fabrication techniques for paper-based microfluidic devices; and (2) exploring new applications of paper-based microfluidics by incorporating efficient detection methods. This paper aims to review both the fabrication techniques and applications of paper-based microfluidics reported to date. This paper also attempts to convey to the readers, from the authors’ point of view the current limitations of paper-based microfluidics which require further research, and a few perspective directions this new analytical system

  7. Biological implications of polydimethylsiloxane-based microfluidic cell culture†

    PubMed Central

    Regehr, Keil J.; Domenech, Maribella; Koepsel, Justin T.; Carver, Kristopher C.; Ellison-Zelski, Stephanie J.; Murphy, William L.; Schuler, Linda A.; Alarid, Elaine T.; Beebe, David J.

    2009-01-01

    Polydimethylsiloxane (PDMS) has become a staple of the microfluidics community by virtue of its simple fabrication process and material attributes, such as gas permeability, optical transparency, and flexibility. As microfluidic systems are put toward biological problems and increasingly utilized as cell culture platforms, the material properties of PDMS must be considered in a biological context. Two properties of PDMS were addressed in this study: the leaching of uncured oligomers from the polymer network into microchannel media, and the absorption of small, hydrophobic molecules (i.e. estrogen) from serum-containing media into the polymer bulk. Uncured PDMS oligomers were detectable via MALDI-MS in microchannel media both before and after Soxhlet extraction of PDMS devices in ethanol. Additionally, PDMS oligomers were identified in the plasma membranes of NMuMG cells cultured in PDMS microchannels for 24 hours. Cells cultured in extracted microchannels also contained a detectable amount of uncured PDMS. It was shown that MCF-7 cells seeded directly on PDMS inserts were responsive to hydrophilic prolactin but not hydrophobic estrogen, reflecting its specificity for absorbing small, hydrophobic molecules; and the presence of PDMS floating in wells significantly reduced cellular response to estrogen in a serum-dependent manner. Quantification of estrogen via ELISA revealed that microchannel estrogen partitioned rapidly into the surrounding PDMS to a ratio of approximately 9:1. Pretreatments such as blocking with serum or pre-absorbing estrogen for 24 hours did not affect estrogen loss from PDMS-based microchannels. These findings highlight the importance of careful consideration of culture system properties when determining an appropriate environment for biological experiments. PMID:19606288

  8. Biological implications of polydimethylsiloxane-based microfluidic cell culture.

    PubMed

    Regehr, Keil J; Domenech, Maribella; Koepsel, Justin T; Carver, Kristopher C; Ellison-Zelski, Stephanie J; Murphy, William L; Schuler, Linda A; Alarid, Elaine T; Beebe, David J

    2009-08-07

    Polydimethylsiloxane (PDMS) has become a staple of the microfluidics community by virtue of its simple fabrication process and material attributes, such as gas permeability, optical transparency, and flexibility. As microfluidic systems are put toward biological problems and increasingly utilized as cell culture platforms, the material properties of PDMS must be considered in a biological context. Two properties of PDMS were addressed in this study: the leaching of uncured oligomers from the polymer network into microchannel media, and the absorption of small, hydrophobic molecules (i.e. estrogen) from serum-containing media into the polymer bulk. Uncured PDMS oligomers were detectable via MALDI-MS in microchannel media both before and after Soxhlet extraction of PDMS devices in ethanol. Additionally, PDMS oligomers were identified in the plasma membranes of NMuMG cells cultured in PDMS microchannels for 24 hours. Cells cultured in extracted microchannels also contained a detectable amount of uncured PDMS. It was shown that MCF-7 cells seeded directly on PDMS inserts were responsive to hydrophilic prolactin but not hydrophobic estrogen, reflecting its specificity for absorbing small, hydrophobic molecules; and the presence of PDMS floating in wells significantly reduced cellular response to estrogen in a serum-dependent manner. Quantification of estrogen via ELISA revealed that microchannel estrogen partitioned rapidly into the surrounding PDMS to a ratio of approximately 9:1. Pretreatments such as blocking with serum or pre-absorbing estrogen for 24 hours did not affect estrogen loss from PDMS-based microchannels. These findings highlight the importance of careful consideration of culture system properties when determining an appropriate environment for biological experiments.

  9. Microfluidic-Based sample chips for radioactive solutions

    DOE PAGES

    Tripp, J. L.; Law, J. D.; Smith, T. E.; ...

    2015-01-01

    Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument wouldmore » greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.« less

  10. Smartphone-based simultaneous pH and nitrite colorimetric determination for paper microfluidic devices.

    PubMed

    Lopez-Ruiz, Nuria; Curto, Vincenzo F; Erenas, Miguel M; Benito-Lopez, Fernando; Diamond, Dermot; Palma, Alberto J; Capitan-Vallvey, Luis F

    2014-10-07

    In this work, an Android application for measurement of nitrite concentration and pH determination in combination with a low-cost paper-based microfluidic device is presented. The application uses seven sensing areas, containing the corresponding immobilized reagents, to produce selective color changes when a sample solution is placed in the sampling area. Under controlled conditions of light, using the flash of the smartphone as a light source, the image captured with the built-in camera is processed using a customized algorithm for multidetection of the colored sensing areas. The developed image-processing allows reducing the influence of the light source and the positioning of the microfluidic device in the picture. Then, the H (hue) and S (saturation) coordinates of the HSV color space are extracted and related to pH and nitrite concentration, respectively. A complete characterization of the sensing elements has been carried out as well as a full description of the image analysis for detection. The results show good use of a mobile phone as an analytical instrument. For the pH, the resolution obtained is 0.04 units of pH, 0.09 of accuracy, and a mean squared error of 0.167. With regard to nitrite, 0.51% at 4.0 mg L(-1) of resolution and 0.52 mg L(-1) as the limit of detection was achieved.

  11. Polymeric nanofiber web-based artificial renal microfluidic chip.

    PubMed

    Lee, K H; Kim, D J; Min, B G; Lee, S H

    2007-08-01

    In this paper, we present a new method for the creation of a smaller dialyzer and do so by incorporating polymeric nanofiber web, which is known to have good filtration efficiency for broad particle sizes, into a poly (dimethylsiloxane)-based microplatform. We have developed a process that makes possible the efficient production of polyethersulfone and polyurethane nanofiber web and that, itself, incorporates an electrospinning method. We have combined the nanofiber web with the PDMS-based microfluidic platform to create a chip-based portable hemodialysis system. With the dialyzing chip, we evaluated the filtration capability of molecules in broad ranges of sizes and compared the filtration capability of nanofiber membranes with that of PES and polyvinylidene fluoride porous membranes (sheet type): we discovered that the nanofiber membranes have better filtration performance than the other membranes. Blood cells were not mechanically affected during their filtration and their transportation through the chip. In conclusion, we have demonstrated the feasibility of chip-based hemodialysis, and we expect that our method suggested in this paper will be applied to the development of small light-weight dialyzers for the realization of portable hemodialysis systems.

  12. Microfluidics for cell-based high throughput screening platforms - A review.

    PubMed

    Du, Guansheng; Fang, Qun; den Toonder, Jaap M J

    2016-01-15

    In the last decades, the basic techniques of microfluidics for the study of cells such as cell culture, cell separation, and cell lysis, have been well developed. Based on cell handling techniques, microfluidics has been widely applied in the field of PCR (Polymerase Chain Reaction), immunoassays, organ-on-chip, stem cell research, and analysis and identification of circulating tumor cells. As a major step in drug discovery, high-throughput screening allows rapid analysis of thousands of chemical, biochemical, genetic or pharmacological tests in parallel. In this review, we summarize the application of microfluidics in cell-based high throughput screening. The screening methods mentioned in this paper include approaches using the perfusion flow mode, the droplet mode, and the microarray mode. We also discuss the future development of microfluidic based high throughput screening platform for drug discovery.

  13. Dynamics of individual polymers using microfluidic based microcurvilinear flow.

    PubMed

    Cheng, Chao-Min; Kim, Yongtae; Yang, Jui-Ming; Leuba, Sanford H; Leduc, Philip R

    2009-08-21

    Polymer dynamics play an important role in a diversity of fields including materials science, physics, biology and medicine. The spatiotemporal responses of individual molecules such as biopolymers have been critical to the development of new materials, the expanded understanding of cell structures including cytoskeletal dynamics, and DNA replication. The ability to probe single molecule dynamics however is often limited by the availability of small-scale technologies that can manipulate these systems to uncover highly intricate behaviors. Advances in micro- and nano-scale technologies have simultaneously provided us with valuable tools that can interface with these systems including methods such as microfluidics. Here, we report on the creation of micro-curvilinear flow through a small-scale fluidic approach, which we have been used to impose a flow-based high radial acceleration ( approximately 10(3) g) on individual flexible polymers. We were able to employ this microfluidic-based approach to adjust and control flow velocity and acceleration to observe real-time dynamics of fluorescently labeled lambda-phage DNA molecules in our device. This allowed us to impose mechanical stimulation including stretching and bending on single molecules in localized regimes through a simple and straightforward technology-based method. We found that the flexible DNA molecules exhibited multimodal responses including distinct conformations and controllable curvatures; these characteristics were directly related to both the elongation and bending dynamics dictated by their locations within the curvilinear flow. We analyzed the dynamics of these individual molecules to determine their elongation strain rates and curvatures ( approximately 0.09 microm(-1)) at different locations in this system to probe the individual polymer structural response. These results demonstrate our ability to create high radial acceleration flow and observe real-time dynamic responses applied directly to

  14. Integrated microfluidics based on multi-layered SU-8 for mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Carlier, J.; Arscott, S.; Thomy, V.; Fourrier, J. C.; Caron, F.; Camart, J. C.; Druon, C.; Tabourier, P.

    2004-04-01

    We present a design for integrated lab-on-chip microsystems dedicated to mass spectrometry analysis based on the fabrication of watertight microchannels for the circulation of liquids. In this paper, we demonstrate how to fabricate complete polymer microchannels using the negative photoresist SU-8 which has the advantage of being compatible with protein analysis by mass spectrometry. Our method of fabrication requires novel technological steps involving SU-8 multi-layer processing, improved SU-8 adhesion and the use of SU-8 wafer bonding for the watertight closing of the microchannels with a Pyrex wafer. This technique also encompasses the design of various microfluidic elements such as tapered recesses for the housing of capillary tubes allowing the connection of the channels to external systems. Following this, the capillary tubes were used to test the hydrodynamic behaviour of the channels and consequently the efficiency of our technological process in achieving fully watertight structures within our flow rate and pressure specifications.

  15. Microfluidic-based single cell trapping using a combination of stagnation point flow and physical barrier

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Chen, Zongzheng; Xiang, Cheng; Liu, Bo; Xie, Handi; Qin, Kairong

    2016-06-01

    Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the relationship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based microfluidic device for single cell trapping is designed using a combination of stagnation point flow and physical barrier. The microfluidic device overcomes the weakness of the traditional ones, which have been only based upon either stagnation point flows or physical barriers, and can conveniently load dynamic biochemical signals to the trapped cell. In addition, it can connect with a programmable syringe pump and a microscope to constitute an integrated experimental system. It is experimentally verified that the microfluidic system can trap single cells in vitro even under flow disturbance and conveniently load biochemical signals to the trapped cell. The designed micro-device would provide a simple yet effective experimental platform for further study of the interactions between single cells and their microenvironments.

  16. Digital microfluidic magnetic separation for particle-based immunoassays.

    PubMed

    Ng, Alphonsus H C; Choi, Kihwan; Luoma, Robert P; Robinson, John M; Wheeler, Aaron R

    2012-10-16

    We introduce a new format for particle-based immunoassays relying on digital microfluidics (DMF) and magnetic forces to separate and resuspend antibody-coated paramagnetic particles. In DMF, fluids are electrostatically controlled as discrete droplets (picoliters to microliters) on an array of insulated electrodes. By applying appropriate sequences of potentials to these electrodes, multiple droplets can be manipulated simultaneously and various droplet operations can be achieved using the same device design. This flexibility makes DMF well-suited for applications that require complex, multistep protocols such as immunoassays. Here, we report the first particle-based immunoassay on DMF without the aid of oil carrier fluid to enable droplet movement (i.e., droplets are surrounded by air instead of oil). This new format allowed the realization of a novel on-chip particle separation and resuspension method capable of removing greater than 90% of unbound reagents in one step. Using this technique, we developed methods for noncompetitive and competitive immunoassays, using thyroid stimulating hormone (TSH) and 17β-estradiol (E2) as model analytes, respectively. We show that, compared to conventional methods, the new DMF approach reported here reduced reagent volumes and analysis time by 100-fold and 10-fold, respectively, while retaining a level of analytical performance required for clinical screening. Thus, we propose that the new technique has great potential for eventual use in a fast, low-waste, and inexpensive instrument for the quantitative analysis of proteins and small molecules in low sample volumes.

  17. Development of a microfluidic chip-based plasmid miniprep.

    PubMed

    Northrup, Victoria A; Backhouse, Christopher J; Glerum, D Moira

    2010-07-15

    Plasmids are the workhorse of contemporary molecular biology, serving as vectors in the multitude of molecular cloning approaches now available. Plasmid minipreps are a routine and essential means of extracting plasmid DNA from bacteria, such as Escherichia coli, for identification, characterization, and further manipulation. Although there have been many approaches described and miniprep kits are commercially available, traditional minipreps typically require more than 16h, including the time needed for bacterial cell culture. Here we describe the development of a microfluidic chip (MFC)-based miniprep that uses on-chip lysis and trapping of large DNA in agarose to differentially separate plasmid DNA from the bacterial chromosome. Our approach greatly decreases both the time required for the miniprep itself and the time required for growth of the bacterial cultures because our on-chip miniprep uses 10(5) times fewer E. coli cells. Because the quality of the isolated plasmid is comparable to that obtained using conventional miniprep protocols, this approach allows growth of E. coli and isolation of plasmid within hours, thereby making it ideal for rapid screening approaches. This MFC-based miniprep, coupled with recently demonstrated on-chip transfection capabilities, lays the groundwork for seamless manipulation of plasmids on MFC platforms.

  18. Development of an evaporation-based microfluidic sample concentrator

    NASA Astrophysics Data System (ADS)

    Sharma, Nigel R.; Lukyanov, Anatoly; Bardell, Ron L.; Seifried, Lynn; Shen, Mingchao

    2008-02-01

    MicroPlumbers Microsciences LLC, has developed a relatively simple concentrator device based on isothermal evaporation. The device allows for rapid concentration of dissolved or dispersed substances or microorganisms (e.g. bacteria, viruses, proteins, toxins, enzymes, antibodies, etc.) under conditions gentle enough to preserve their specific activity or viability. It is capable of removing of 0.8 ml of water per minute at 37°C, and has dimensions compatible with typical microfluidic devices. The concentrator can be used as a stand-alone device or integrated into various processes and analytical instruments, substantially increasing their sensitivity while decreasing processing time. The evaporative concentrator can find applications in many areas such as biothreat detection, environmental monitoring, forensic medicine, pathogen analysis, and agricultural industrial monitoring. In our presentation, we describe the design, fabrication, and testing of the concentrator. We discuss multiphysics simulations of the heat and mass transport in the device that we used to select the design of the concentrator and the protocol of performance testing. We present the results of experiments evaluating water removal performance.

  19. Structural studies of enzyme-based microfluidic biofuel cells

    NASA Astrophysics Data System (ADS)

    Togo, Makoto; Takamura, Akimasa; Asai, Tatsuya; Kaji, Hirokazu; Nishizawa, Matsuhiko

    An enzyme-based glucose/O 2 biofuel cell was constructed within a microfluidic channel to study the influence of electrode configuration and fluidic channel height on cell performance. The cell was composed of a bilirubin oxidase (BOD)-adsorbed O 2 cathode and a glucose anode prepared by co-immobilization of glucose dehydrogenase (GDH), diaphorase (Dp) and VK 3-pendant poly- L-lysine. The consumption of O 2 at the upstream cathode protected the downstream anode from interfering O 2 molecules, and consequently improved the cell performance (maximum cell current) ca. 10% for the present cell. The cell performance was also affected by the channel height. The output current and power of a 0.1 mm-height cell was significantly less than those of a 1 mm-height cell because of the depletion of O 2, as determined by the shape of the E- I curve at the cathode. On the other hand, the volume density of current and power was several times higher for the narrower cell.

  20. A microfluidic paper-based device to assess acetylcholinesterase activity.

    PubMed

    Liu, Chunye; Gomez, Frank A

    2017-04-01

    Neurotransmitters play key roles in cell-to-cell communication. These chemical messengers are involved in many functional processes, including growth, reproduction, memory, and behavior. In this communication, we describe a novel microfluidic paper-based analytical device (μPAD) to detect acetylcholinesterase (AChE) activity and inhibitor screening through a colorimetric analysis. The μPAD is easily fabricated via a wax printing process whereby wax is deposited onto the surface of chromatographic paper, and heated to create a hydrophobic barrier. Separate solutions of 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) and samples containing AChE and acetylthiocholine iodide (ATC) (or cysteine, Cys), respectively, are directly spotted onto the μPAD. DTNB and AChE/ATC (or Cys) flow towards each other where a reaction occurs to form the yellow colored 2-nitro-5-thiobenzoic acid anion (TNB(2-) ). The device is dried, scanned, and analyzed yielding a linear range of average inverse yellow intensities versus substrate concentration. An IC50 value (0.045 nM) with a known inhibitor, neostigmine bromide (NB), is obtained on the device. μPADs are low cost and easy to fabricate and have great potential to quantify neurotransmitter activity.

  1. A portable, integrated analyzer for microfluidic - based molecular analysis.

    PubMed

    Qiu, Xianbo; Chen, Dafeng; Liu, Changchun; Mauk, Michael G; Kientz, Terry; Bau, Haim H

    2011-10-01

    A portable, fully automated analyzer that provides actuation and flow control to a disposable, self-contained, microfluidic cassette ("chip") for point-of-care, molecular testing is described. The analyzer provides mechanical actuation to compress pouches that pump liquids in the cassette, to open and close diaphragm valves for flow control, and to induce vibrations that enhance stirring. The analyzer also provides thermal actuation for the temperature cycling needed for polymerase chain reaction (PCR) amplification of nucleic acids and for various drying processes. To improve the temperature uniformity of the PCR chamber, the system utilizes a double-sided heating/cooling scheme with a custom feedforward, variable, structural proportional-integral-derivative (FVSPID) controller. The analyzer includes a programmable central processing unit that directs the sequence and timing of the various operations and that is interfaced with a computer. The disposable cassette receives a sample, and it carries out cell lysis, nucleic acid isolation, concentration, and purification, thermal cycling, and either real time or lateral flow (LF) based detection. The system's operation was demonstrated by processing saliva samples spiked with B. cereus cells. The amplicons were detected with a lateral flow assay using upconverting phosphor reporter particles. This system is particularly suited for use in regions lacking centralized laboratory facilities and skilled personnel.

  2. Model-based feedback control of a microfluidic electroporation system

    NASA Astrophysics Data System (ADS)

    Ghadami, M.; Mahjoob, M. J.; Shagoshtasbi, H.; Lee, Y.-K.

    2013-12-01

    This paper describes new model-based feedback control method used for a single-cell microfluidic electroporation (EP) system. For this purpose, a new four-state nonlinear model has been developed to describe dynamics of a micro-channel electroporation system. EP measured current response is then used to verify the efficiency of the proposed new EP model. Consequently, two feedback control methods, namely, proportional-integral-derivative controller and model predictive controller have been applied to regulate the key states (i.e. transmembrane voltage (Vm) and nano-electropore radius (r)) in the EP model. Numerical simulations of static and dynamic responses of the two critical states, Vm and r, show that feedback control can improve the cell viability and EP efficiency compared to the open-loop system. In the experimental phase, a fabricated micro-EP chip with integrated Coulter counter is used to define the cell-size-dependent parameters of the EP model and electroporation of HeLa cells. In this phase, the EP model is also inserted into LabView software's environment to estimate the value of transmembrane voltage during the experiment. Variation of the external applied voltage derived from experimental result was in good adaptation with its equivalent theoretical values.

  3. Fabrication of polyimide based microfluidic channels for biosensor devices

    NASA Astrophysics Data System (ADS)

    Zulfiqar, Azeem; Pfreundt, Andrea; Svendsen, Winnie Edith; Dimaki, Maria

    2015-03-01

    The ever-increasing complexity of the fabrication process of Point-of-care (POC) devices, due to high demand of functional versatility, compact size and ease-of-use, emphasizes the need of multifunctional materials that can be used to simplify this process. Polymers, currently in use for the fabrication of the often needed microfluidic channels, have limitations in terms of their physicochemical properties. Therefore, the use of a multipurpose biocompatible material with better resistance to the chemical, thermal and electrical environment, along with capability of forming closed channel microfluidics is inevitable. This paper demonstrates a novel technique of fabricating microfluidic devices using polyimide (PI) which fulfills the aforementioned properties criteria. A fabrication process to pattern microfluidic channels, using partially cured PI, has been developed by using a dry etching method. The etching parameters are optimized and compared to those used for fully cured PI. Moreover, the formation of closed microfluidic channel on wafer level by bonding two partially cured PI layers or a partially cured PI to glass with high bond strength has been demonstrated. The reproducibility in uniformity of PI is also compared to the most commonly used SU8 polymer, which is a near UV sensitive epoxy resin. The potential applications of PI processing are POC and biosensor devices integrated with microelectronics.

  4. Sample pretreatment and nucleic acid-based detection for fast diagnosis utilizing microfluidic systems.

    PubMed

    Wang, Jung-Hao; Wang, Chih-Hung; Lee, Gwo-Bin

    2012-06-01

    Recently, micro-electro-mechanical-systems (MEMS) technology and micromachining techniques have enabled miniaturization of biomedical devices and systems. Not only do these techniques facilitate the development of miniaturized instrumentation for biomedical analysis, but they also open a new era for integration of microdevices for performing accurate and sensitive diagnostic assays. A so-called "micro-total-analysis-system", which integrates sample pretreatment, transport, reaction, and detection on a small chip in an automatic format, can be realized by combining functional microfluidic components manufactured by specific MEMS technologies. Among the promising applications using microfluidic technologies, nucleic acid-based detection has shown considerable potential recently. For instance, micro-polymerase chain reaction chips for rapid DNA amplification have attracted considerable interest. In addition, microfluidic devices for rapid sample pretreatment prior to nucleic acid-based detection have also achieved significant progress in the recent years. In this review paper, microfluidic systems for sample preparation, nucleic acid amplification and detection for fast diagnosis will be reviewed. These microfluidic devices and systems have several advantages over their large-scale counterparts, including lower sample/reagent consumption, lower power consumption, compact size, faster analysis, and lower per unit cost. The development of these microfluidic devices and systems may provide a revolutionary platform technology for fast sample pretreatment and accurate, sensitive diagnosis.

  5. Droplet-based microfluidics: enabling impact on drug discovery.

    PubMed

    Dressler, Oliver J; Maceiczyk, Richard M; Chang, Soo-Ik; deMello, Andrew J

    2014-04-01

    Over the past two decades, the application of microengineered systems in the chemical and biological sciences has transformed the way in which high-throughput experimentation is performed. The ability to fabricate complex microfluidic architectures has allowed scientists to create new experimental formats for processing ultra-small analytical volumes in short periods and with high efficiency. The development of such microfluidic systems has been driven by a range of fundamental features that accompany miniaturization. These include the ability to handle small sample volumes, ultra-low fabrication costs, reduced analysis times, enhanced operational flexibility, facile automation, and the ability to integrate functional components within complex analytical schemes. Herein we discuss the impact of microfluidics in the area of high-throughput screening and drug discovery and highlight some of the most pertinent studies in the recent literature.

  6. Automated microfluidic screening assay platform based on DropLab.

    PubMed

    Du, Wen-Bin; Sun, Meng; Gu, Shu-Qing; Zhu, Ying; Fang, Qun

    2010-12-01

    This paper describes DropLab, an automated microfluidic platform for programming droplet-based reactions and screening in the nanoliter range. DropLab can meter liquids with picoliter-scale precision, mix multiple components sequentially to assemble composite droplets, and perform screening reactions and assays in linear or two-dimensional droplet array with extremely low sample and reagent consumptions. A novel droplet generation approach based on the droplet assembling strategy was developed to produce multicomponent droplets in the nanoliter to picoliter range with high controllability on the size and composition of each droplet. The DropLab system was built using a short capillary with a tapered tip, a syringe pump with picoliter precision, and an automated liquid presenting system. The tapered capillary was used for precise liquid metering and mixing, droplet assembling, and droplet array storage. Two different liquid presenting systems were developed based on the slotted-vial array design and multiwell plate design to automatically present various samples, reagents, and oil to the capillary. Using the tapered-tip capillary and the picoliter-scale precision syringe pump, the minimum unit of the droplet volume in the present system reached ~20 pL. Without the need of complex microchannel networks, various droplets with different size (20 pL-25 nL), composition, and sequence were automatically assembled, aiming to multiple screening targets by simply adjusting the types, volumes, and mixing ratios of aspirated liquids on demand. The utility of DropLab was demonstrated in enzyme inhibition assays, protein crystallization screening, and identification of trace reducible carbohydrates.

  7. Image-guided, Laser-based Fabrication of Vascular-derived Microfluidic Networks.

    PubMed

    Heintz, Keely A; Mayerich, David; Slater, John H

    2017-01-03

    This detailed protocol outlines the implementation of image-guided, laser-based hydrogel degradation for the fabrication of vascular-derived microfluidic networks embedded in PEGDA hydrogels. Here, we describe the creation of virtual masks that allow for image-guided laser control; the photopolymerization of a micromolded PEGDA hydrogel, suitable for microfluidic network fabrication and pressure head-driven flow; the setup and use of a commercially available laser scanning confocal microscope paired with a femtosecond pulsed Ti:S laser to induce hydrogel degradation; and the imaging of fabricated microfluidic networks using fluorescent species and confocal microscopy. Much of the protocol is focused on the proper setup and implementation of the microscope software and microscope macro, as these are crucial steps in using a commercial microscope for microfluidic fabrication purposes that contain a number of intricacies. The image-guided component of this technique allows for the implementation of 3D image stacks or user-generated 3D models, thereby allowing for creative microfluidic design and for the fabrication of complex microfluidic systems of virtually any configuration. With an expected impact in tissue engineering, the methods outlined in this protocol could aid in the fabrication of advanced biomimetic microtissue constructs for organ- and human-on-a-chip devices. By mimicking the complex architecture, tortuosity, size, and density of in vivo vasculature, essential biological transport processes can be replicated in these constructs, leading to more accurate in vitro modeling of drug pharmacokinetics and disease.

  8. Characterization of a microfluidic microbial fuel cell as a power generator based on a nickel electrode.

    PubMed

    Mardanpour, Mohammad Mahdi; Yaghmaei, Soheila

    2016-05-15

    This study reports the fabrication of a microfluidic microbial fuel cell (MFC) using nickel as a novel alternative for conventional electrodes and a non-phatogenic strain of Escherichia coli as the biocatalyst. The feasibility of a microfluidic MFC as an efficient power generator for production of bioelectricity from glucose and urea as organic substrates in human blood and urine for implantable medical devices (IMDs) was investigated. A maximum open circuit potential of 459 mV was achieved for the batch-fed microfluidic MFC. During continuous mode operation, a maximum power density of 104 Wm(-3) was obtained with nutrient broth. For the glucose-fed microfluidic MFC, the maximum power density of 5.2 μW cm(-2) obtained in this study is significantly greater than the power densities reported previously for microsized MFCs and glucose fuel cells. The maximum power density of 14 Wm(-3) obtained using urea indicates the successful performance of a microfluidic MFC using human excreta. It features high power density, self-regeneration, waste management and a low production cost (<$1), which suggest it as a promising alternative to conventional power supplies for IMDs. The performance of the microfluidic MFC as a power supply was characterized based on polarization behavior and cell potential in different substrates, operational modes, and concentrations.

  9. Monolithical integration of polymer-based microfluidic structures on application-specific integrated circuits

    NASA Astrophysics Data System (ADS)

    Chemnitz, Steffen; Schafer, Heiko; Schumacher, Stephanie; Koziy, Volodymyr; Fischer, Alexander; Meixner, Alfred J.; Ehrhardt, Dietmar; Bohm, Markus

    2003-04-01

    In this paper, a concept for a monolithically integrated chemical lab on microchip is presented. It contains an ASIC (Application Specific Integrated Circuit), an interface to the polymer based microfluidic layer and a Pyrex glass cap. The top metal layer of the ASIC is etched off and replaced by a double layer metallization, more suitable to microfluidic and electrophoresis systems. The metallization consists of an approximately 50 nm gold layer and a 10 nm chromium layer, acting as adhesion promoter. A necessary prerequisite is a planarized ASIC topography. SU-8 is used to serve as microfluidic structure because of its excellent aspect ratio. This polymer layer contains reservoirs, channels, mixers and electrokinetic micro pumps. The typical channel cross section is 10μm"10μm. First experimental results on a microfluidic pump, consisting of pairs of interdigitated electrodes on the bottom of the channel and without any moving parts show a flow of up to 50μm per second for low AC-voltages in the range of 5 V for aqueous fluids. The microfluidic system is irreversibly sealed with a 150μm thick Pyrex glass plate bonded to the SU-8-layer, supported by oxygen plasma. Due to capillary forces and surfaces properties of the walls the system is self-priming. The technologies for the fabrication of the microfluidic system and the preparation of the interface between the lab layer and the ASIC are presented.

  10. Screening applications in drug discovery based on microfluidic technology

    PubMed Central

    Eribol, P.; Uguz, A. K.; Ulgen, K. O.

    2016-01-01

    Microfluidics has been the focus of interest for the last two decades for all the advantages such as low chemical consumption, reduced analysis time, high throughput, better control of mass and heat transfer, downsizing a bench-top laboratory to a chip, i.e., lab-on-a-chip, and many others it has offered. Microfluidic technology quickly found applications in the pharmaceutical industry, which demands working with leading edge scientific and technological breakthroughs, as drug screening and commercialization are very long and expensive processes and require many tests due to unpredictable results. This review paper is on drug candidate screening methods with microfluidic technology and focuses specifically on fabrication techniques and materials for the microchip, types of flow such as continuous or discrete and their advantages, determination of kinetic parameters and their comparison with conventional systems, assessment of toxicities and cytotoxicities, concentration generations for high throughput, and the computational methods that were employed. An important conclusion of this review is that even though microfluidic technology has been in this field for around 20 years there is still room for research and development, as this cutting edge technology requires ingenuity to design and find solutions for each individual case. Recent extensions of these microsystems are microengineered organs-on-chips and organ arrays. PMID:26865904

  11. Screening applications in drug discovery based on microfluidic technology.

    PubMed

    Eribol, P; Uguz, A K; Ulgen, K O

    2016-01-01

    Microfluidics has been the focus of interest for the last two decades for all the advantages such as low chemical consumption, reduced analysis time, high throughput, better control of mass and heat transfer, downsizing a bench-top laboratory to a chip, i.e., lab-on-a-chip, and many others it has offered. Microfluidic technology quickly found applications in the pharmaceutical industry, which demands working with leading edge scientific and technological breakthroughs, as drug screening and commercialization are very long and expensive processes and require many tests due to unpredictable results. This review paper is on drug candidate screening methods with microfluidic technology and focuses specifically on fabrication techniques and materials for the microchip, types of flow such as continuous or discrete and their advantages, determination of kinetic parameters and their comparison with conventional systems, assessment of toxicities and cytotoxicities, concentration generations for high throughput, and the computational methods that were employed. An important conclusion of this review is that even though microfluidic technology has been in this field for around 20 years there is still room for research and development, as this cutting edge technology requires ingenuity to design and find solutions for each individual case. Recent extensions of these microsystems are microengineered organs-on-chips and organ arrays.

  12. Blood separation on microfluidic paper-based analytical devices.

    PubMed

    Songjaroen, Temsiri; Dungchai, Wijitar; Chailapakul, Orawon; Henry, Charles S; Laiwattanapaisal, Wanida

    2012-09-21

    A microfluidic paper-based analytical device (μPAD) for the separation of blood plasma from whole blood is described. The device can separate plasma from whole blood and quantify plasma proteins in a single step. The μPAD was fabricated using the wax dipping method, and the final device was composed of a blood separation membrane combined with patterned Whatman No.1 paper. Blood separation membranes, LF1, MF1, VF1 and VF2 were tested for blood separation on the μPAD. The LF1 membrane was found to be the most suitable for blood separations when fabricating the μPAD by wax dipping. For blood separation, the blood cells (both red and white) were trapped on blood separation membrane allowing pure plasma to flow to the detection zone by capillary force. The LF1-μPAD was shown to be functional with human whole blood of 24-55% hematocrit without dilution, and effectively separated blood cells from plasma within 2 min when blood volumes of between 15-22 μL were added to the device. Microscopy was used to confirm that the device isolated plasma with high purity with no blood cells or cell hemolysis in the detection zone. The efficiency of blood separation on the μPAD was studied by plasma protein detection using the bromocresol green (BCG) colorimetric assay. The results revealed that protein detection on the μPAD was not significantly different from the conventional method (p > 0.05, pair t-test). The colorimetric measurement reproducibility on the μPAD was 2.62% (n = 10) and 5.84% (n = 30) for within-day and between day precision, respectively. Our proposed blood separation on μPAD has the potential for reducing turnaround time, sample volume, sample preparation and detection processes for clinical diagnosis and point-of care testing.

  13. Fabrication of advanced particles and particle-based materials assisted by droplet-based microfluidics.

    PubMed

    Wang, Jing-Tao; Wang, Juan; Han, Jun-Jie

    2011-07-04

    Recent advances in the fabrication of complex particles and particle-based materials assisted by droplet-based microfluidics are reviewed. Monodisperse particles with expected internal structures, morphologies, and sizes in the range of nanometers to hundreds of micrometers have received a good deal of attention in recent years. Due to the capability of generating monodisperse emulsions and of executing precise control and operations on the suspended droplets inside the microchannels, droplet-based microfluidic devices have become powerful tools for fabricating complex particles with desired properties. Emulsions and multiple-emulsions generated in the microfluidic devices can be composed of a variety of materials including aqueous solutions, gels, polymers and solutions containing functional nanoparticles. They are ideal microreactors or fine templates for synthesizing advanced particles, such as polymer particles, microcapsules, nanocrystals, and photonic crystal clusters or beads by further chemical or physical operations. These particles are promising materials that may be applicable for many fields, such as photonic materials, drug delivery systems, and bio-analysis. From simple to complex, from spherical to nonspherical, from polymerization and reaction crystallization to self-assembly, this review aims to help readers be aware of the many aspects of this field.

  14. A digital microfluidic method for multiplexed cell-based apoptosis assays.

    PubMed

    Bogojevic, Dario; Chamberlain, M Dean; Barbulovic-Nad, Irena; Wheeler, Aaron R

    2012-02-07

    Digital microfluidics (DMF), a fluid-handling technique in which picolitre-microlitre droplets are manipulated electrostatically on an array of electrodes, has recently become popular for applications in chemistry and biology. DMF devices are reconfigurable, have no moving parts, and are compatible with conventional high-throughput screening infrastructure (e.g., multiwell plate readers). For these and other reasons, digital microfluidics has been touted as being a potentially useful new tool for applications in multiplexed screening. Here, we introduce the first digital microfluidic platform used to implement parallel-scale cell-based assays. A fluorogenic apoptosis assay for caspase-3 activity was chosen as a model system because of the popularity of apoptosis as a target for anti-cancer drug discovery research. Dose-response profiles of caspase-3 activity as a function of staurosporine concentration were generated using both the digital microfluidic method and conventional techniques (i.e., pipetting, aspiration, and 96-well plates.) As expected, the digital microfluidic method had a 33-fold reduction in reagent consumption relative to the conventional technique. Although both types of methods used the same detector (a benchtop multiwell plate reader), the data generated by the digital microfluidic method had lower detection limits and greater dynamic range because apoptotic cells were much less likely to de-laminate when exposed to droplet manipulation by DMF relative to pipetting/aspiration in multiwell plates. We propose that the techniques described here represent an important milestone in the development of digital microfluidics as a useful tool for parallel cell-based screening and other applications.

  15. 2-layer based microfluidic concentration generator by hybrid serial and volumetric dilutions.

    PubMed

    Lee, Kangsun; Kim, Choong; Kim, Youngeun; Jung, Keunhui; Ahn, Byungwook; Kang, Ji Yoon; Oh, Kwang W

    2010-04-01

    We present a 2-layer based microfluidic concentration generator by a hybrid of a serial and a volumetric dilution for dose-response experiments in drug screening. The hybrid dilution method using 2-layer based microfluidic network significantly reduces the total number of cascaded serial dilution stages. The proposed strategy is capable of generating a large number of universal stepwise monotonic concentrations with a wide range of logarithmic and linear scales. We have studied an equivalent electrical circuit to that of the 2-layer based microfluidic network, where the only variable parameter is channel length. We have designed a microfluidic dilution generator simultaneously covering 14 doses with a combination of 4-order logarithmic and 4-point linear concentrations. The design has been verified by a commercial circuit analysis software (e.g., P-Spice) for the electrical circuit analysis and a computational fluid dynamics software (e.g., CFD-ACE+) for the microfluidic circuit analysis. As a real-life application of the proposed dilution generator, we have successfully performed a dose-response experiment using MCF-7 human breast cancer cells. We expect that the proposed dilution method will be useful to study not only high throughput drug screening but also optimization in biology, chemistry, medicine, and material sciences.

  16. Rapid prototyping of arrayed microfluidic systems in polystyrene for cell-based assays.

    PubMed

    Young, Edmond W K; Berthier, Erwin; Guckenberger, David J; Sackmann, Eric; Lamers, Casey; Meyvantsson, Ivar; Huttenlocher, Anna; Beebe, David J

    2011-02-15

    Microfluidic cell-based systems have enabled the study of cellular phenomena with improved spatiotemporal control of the microenvironment and at increased throughput. While poly(dimethylsiloxane) (PDMS) has emerged as the most popular material in microfluidics research, it has specific limitations that prevent microfluidic platforms from achieving their full potential. We present here a complete process, ranging from mold design to embossing and bonding, that describes the fabrication of polystyrene (PS) microfluidic devices with similar cost and time expenditures as PDMS-based devices. Emphasis was placed on creating methods that can compete with PDMS fabrication methods in terms of robustness, complexity, and time requirements. To achieve this goal, several improvements were made to remove critical bottlenecks in existing PS embossing methods. First, traditional lithographic techniques were adapted to fabricate bulk epoxy molds capable of resisting high temperatures and pressures. Second, a method was developed to emboss through-holes in a PS layer, enabling creation of large arrays of independent microfluidic systems on a single device without need to manually create access ports. Third, thermal bonding of PS layers was optimized in order to achieve quality bonding over large arrays of microsystems. The choice of materials and methods was validated for biological function in two different cell-based applications to demonstrate the versatility of our streamlined fabrication process.

  17. Rapid prototyping of arrayed microfluidic systems in polystyrene for cell-based assays

    PubMed Central

    Young, Edmond W.K.; Berthier, Erwin; Guckenberger, David J.; Sackmann, Eric; Lamers, Casey; Meyvantsson, Ivar; Huttenlocher, Anna; Beebe, David J.

    2011-01-01

    Microfluidic cell-based systems have enabled the study of cellular phenomena with improved spatiotemporal control of the microenvironment and at increased throughput. While PDMS has emerged as the most popular material in microfluidics research, it has specific limitations that prevent microfluidic platforms from achieving their full potential. We present here a complete process, ranging from mold design to embossing and bonding, that describes the fabrication of polystyrene (PS) microfluidic devices with similar cost and time expenditures as PDMS-based devices. Emphasis was placed on creating methods that can compete with PDMS fabrication methods in terms of robustness, complexity and time requirements. To achieve this goal several improvements were made to remove critical bottlenecks in existing PS embossing methods. First, traditional lithography techniques were adapted to fabricate bulk epoxy molds capable of resisting high temperatures and pressures. Second, a method was developed to emboss through-holes in a PS layer, enabling creation of large arrays of independent microfluidic systems on a single device without need to manually create access ports. Third, thermal bonding of PS layers was optimized in order to achieve quality bonding over large arrays of microsystems. The choice of materials and methods were validated for biological function using two different cell-based applications to demonstrate the versatility of our streamlined fabrication process. PMID:21261280

  18. Single-layer planar on-chip flow cytometer using microfluidic drifting based three-dimensional (3D) hydrodynamic focusing.

    PubMed

    Mao, Xiaole; Lin, Sz-Chin Steven; Dong, Cheng; Huang, Tony Jun

    2009-06-07

    In this work, we demonstrate an on-chip microfluidic flow cytometry system based on a three-dimensional (3D) hydrodynamic focusing technique, microfluidic drifting. By inducing Dean flow in a curved microfluidic channel, microfluidic drifting can be used to hydrodynamically focus cells or particles in the vertical direction and enables the 3D hydrodynamic focusing in a single-layer planar microfluidic device. Through theoretical calculation, numerical simulation, and experimental characterization, we found that the microfluidic drifting technique can be effectively applied to three-dimensionally focus microparticles with density and size equivalent to those of human CD4+ T lymphocytes. In addition, we developed a flow cytometry platform by integrating the 3D focusing device with a laser-induced fluorescence (LIF) detection system. The system was shown to provide effective high-throughput flow cytometry measurements at a rate of greater than 1700 cells s(-1).

  19. A portable microfluidic-based biophotonic sensor for extracellular H2O2 measurements

    NASA Astrophysics Data System (ADS)

    Koman, V.; Suárez, G.; Santschi, Ch.; Cadarso, V. J.; Brugger, J.; von Moos, N.; Slaveykova, V. I.; Martin, O. J. F.

    2013-03-01

    In this work a portable analytical biosensor for real-time extracellular monitoring of released hydrogen peroxide (H2O2 ) is presented. The biosensor is based on the optical detection of the cytochrome c (cyt c) oxidation state. The setup consists of an integrated microscope combined with a compact spectrometer. The light being absorbed by cyt c is enhanced via multiscattering produced by random aggregates of polystyrene beads in a cross-linked cyt c matrix. Using ink-jet printing technique, the sensing elements, namely cyt c loaded polystyrene aggregates, are fabricated with high reliability in terms of repeatability of size and sensitivity. Additionally, the sensing elements are enclosed in a microfluidic channel assuring a fast and efficient analytes delivery. As an example, the effect of trace concentrations of functionalized cadmium selenide/zinc sulfide (CdSe/ZnS) core shell quantum dots on the green algae Chlamydomonas reinhardtii is investigated, showing extracellular H2O2 release with different production rates over a period of 1 hour. In conclusion, the presented portable biosensor enables the highly sensitive and non-invasive real-time monitoring of the cell metabolism of C. reinhardtii.

  20. Demonstration of microcantilever-based sensor array with integrated microfluidics

    NASA Astrophysics Data System (ADS)

    Nordin, Gregory P.; Anderson, Ryan R.; Ness, Stanley J.; Hu, Weisheng; Gustafson, Timothy M.; Noh, Jong W.; Richards, Danny C.; Kim, Seunghyun

    2011-05-01

    We report the integration of a nanomechanical sensor consisting of 16 silicon microcantilevers and polydimethylsiloxane (PDMS) microfluidics. With our recently developed in-plane photonic transduction method we routinely achieve microcantilever transduction responsivities in the range of 0.5-1.1 μm-1, which is comparable to the best reported for the laser reflection readout method used in atomic force microscopy (AFM). Prior work has established that differential surface stress as low as 0.23 mN/m is readily measurable with our arrays. In this paper we show biotin-streptavidin sensing with a differential surface stress of ~2.3 mN/m as a first step toward characterizing integrated microcantilever array/microfluidic sensors.

  1. Image-based analysis of droplets in microfluidics.

    PubMed

    Zantow, Miné; Dendere, Ronald; Douglas, Tania S

    2013-01-01

    In order to design a microfluidic device that can produce monodispersed encapsulated enzymes as droplets, it is essential to be able to evaluate the system during its development. An automated method to determine the size of the droplets as well as a method to tag and track droplets as they move in the system is desirable for system evaluation. We apply the Hough transform for circles to determine droplet size. Most of the droplets in the images are detected, and the best results are obtained at 20x magnification. We also test the ability of the ImageJ 'particle tracker' plugin to determine the behaviour of the droplets as they move in microfluidic systems. It is effective in tracking droplets that travel less than 50 pixels between frames.

  2. A SERS-based microfluidic immunoassay using an in-situ synthesized gold substrate

    NASA Astrophysics Data System (ADS)

    Fan, Kequan; Wang, Zhuyuan; Wu, Lei; Zong, Shenfei; Cui, Yiping

    2015-05-01

    A sensitive SERS (surface-enhanced Raman scattering)-based immunoassay in microfluidic system has been developed with in-situ synthesis of gold substrate and immune reporter named as 4MBA (4-Mercaptobenzoic acid)-labeled immuno-Ag aggregates. The gold substrate was fabricated simply by introducing the hydrogen tetrachloroaurate (III) trihydrate (HAuCl4) solution to microchannels using a microfluidic pump. It was found that the obtained deposited gold nanoparticles were uniform in size and shape. Then the sandwich immunoassays were performed using the gold substrates based on SERS signals. In the immunoassay, the gold nanoparticles decorated surface was modified with certain antibodies to recognize the specific kind of antigen, which was flowed through the microfluidic channel afterwards. Then 4MBA-labeled immuno-Ag aggregates were employed as the SERS probes to quantitatively detect the antigen. The experimental results showed a good specificity and limit of detection (LOD) about 1 ng/mL.

  3. Magnetophoretic-based microfluidic device for DNA isolation.

    PubMed

    Hale, C; Darabi, J

    2014-07-01

    This paper presents a continuous flow microfluidic device for the separation of DNA from blood using magnetophoresis for biological applications and analysis. This microfluidic bio-separation device has several benefits, including decreased sample handling, smaller sample and reagent volumes, faster isolation time, and decreased cost to perform DNA isolation. One of the key features of this device is the use of short-range magnetic field gradients, generated by a micro-patterned nickel array on the bottom surface of the separation channel. In addition, the device utilizes an array of oppositely oriented, external permanent magnets to produce strong long-range field gradients at the interfaces between magnets, further increasing the effectiveness of the device. A comprehensive simulation is performed using COMSOL Multiphysics to study the effect of various parameters on the magnetic flux within the separation channel. Additionally, a microfluidic device is designed, fabricated, and tested to isolate DNA from blood. The results show that the device has the capability of separating DNA from a blood sample with a purity of 1.8 or higher, a yield of up to 33 μg of polymerase chain reaction ready DNA per milliliter of blood, and a volumetric throughput of up to 50 ml/h.

  4. Carbon Nanotube Based Microfluidic Elements for Filtration and Concentration

    SciTech Connect

    Bakajin, O; Ben-Barak, N; Peng, J; Noy, A

    2003-06-25

    We have developed a method for integration of patterned arrays of carbon nanotubes or the ''nanotube mesh'' into microfabricated channels. The method includes standard lithographic methods for patterning and etching the substrate, followed by catalyst patterning, CVD deposition of nanotubes, and anodic bonding of coverslip top. We will describe a carbon nanotube filtering device fabricated using this method and discuss the use of carbon nanotube arrays as molecular concentration and separation media.

  5. Clogging-free microfluidics for continuous size-based separation of microparticles

    PubMed Central

    Yoon, Yousang; Kim, Seonil; Lee, Jusin; Choi, Jaewoong; Kim, Rae-Kwon; Lee, Su-Jae; Sul, Onejae; Lee, Seung-Beck

    2016-01-01

    In microfluidic filtration systems, one of the leading obstacles to efficient, continuous operation is clogging of the filters. Here, we introduce a lateral flow microfluidic sieving (μ-sieving) technique to overcome clogging and to allow continuous operation of filter based microfluidic separation. A low frequency mechanical oscillation was added to the fluid flow, which made possible the release of aggregated unwanted polystyrene (PS) particles trapped between the larger target PS particles in the filter demonstrating continuous μ-sieving operation. We achieved collection of the target PS particles with 100% separation efficiency. Also, on average, more than 98% of the filtered target particles were retrieved after the filtration showing high retrieval rates. Since the oscillation was applied to the fluid but not to the microfluidic filter system, mechanical stresses to the system was minimized and no additional fabrication procedures were necessary. We also applied the μ-sieving technique to the separation of cancer cells (MDA-MB-231) from whole blood and showed that the fluidic oscillations prevented the filters from being blocked by the filtered cancer cells allowing continuous microfluidic separation with high efficiency. PMID:27198601

  6. Fabrication of multilayer-PDMS based microfluidic device for bio-particles concentration detection.

    PubMed

    Masrie, Marianah; Majlis, Burhanuddin Yeop; Yunas, Jumril

    2014-01-01

    This paper discusses the process technology to fabricate multilayer-Polydimethylsiloxane (PDMS) based microfluidic device for bio-particles concentration detection in Lab-on-chip system. The micro chamber and the fluidic channel were fabricated using standard photolithography and soft lithography process. Conventional method by pouring PDMS on a silicon wafer and peeling after curing in soft lithography produces unspecific layer thickness. In this work, a multilayer-PDMS method is proposed to produce a layer with specific and fixed thickness micron size after bonding that act as an optimum light path length for optimum light detection. This multilayer with precise thickness is required since the microfluidic is integrated with optical transducer. Another significant advantage of this method is to provide excellent bonding between multilayer-PDMS layer and biocompatible microfluidic channel. The detail fabrication process were illustrated through scanning electron microscopy (SEM) and discussed in this work. The optical signal responses obtained from the multilayer-PDMS microfluidic channel with integrated optical transducer were compared with those obtained with the microfluidic channel from a conventional method. As a result, both optical signal responses did not show significant differences in terms of dispersion of light propagation for both media.

  7. Microfluidics-Based Biosensors: A Microfluidic Paper-Based Origami Nanobiosensor for Label-Free, Ultrasensitive Immunoassays (Adv. Healthcare Mater. 11/2016).

    PubMed

    Li, Xiao; Liu, Xinyu

    2016-06-01

    The first microfluidic paper-based origami nano-biosensor featuring zinc oxide nanowires and an electrochemical impedance spectroscopy biosensing mechanism, for label-free, ultrasensitive immunoassays is reported by X. Li and X. Liu on page 1326. The sensor consists of cellulose paper, a carbon ink electrode, and zinc oxide nanowires directly grown on the top. Possible parallelization of assays and high storage stability render the sensor promising for clinical diagnostics applications.

  8. Nanostructured anatase-titanium dioxide based platform for application to microfluidics cholesterol biosensor

    NASA Astrophysics Data System (ADS)

    Azahar Ali, Md.; Srivastava, Saurabh; Solanki, Pratima R.; Varun Agrawal, Ved; John, Renu; Malhotra, Bansi D.

    2012-08-01

    We report results of studies relating to the fabrication of a microfluidics cholesterol sensor based on nanocrystalline anatase-titanium dioxide (ant-TiO2) film deposited onto indium tin oxide (ITO) glass. The results of response studies (optimized under the flow rate of 30 μl/min) conducted on cholesterol oxidase (ChOx) immobilized onto crystalline ant-TiO2 nanoparticles (˜27 nm)/ITO microfluidics electrode reveal linearity as 1.3 to 10.3 mM and improved sensitivity of 94.65 μA/mM/cm2. The observed low value of Km (0.14 mM) indicates high affinity of ChOx to cholesterol. No significant changes in current response of this microfluidics sensor are measured in the presence of different interferents.

  9. Automated cell viability assessment using a microfluidics based portable imaging flow analyzer

    PubMed Central

    Jagannadh, Veerendra Kalyan; Adhikari, Jayesh Vasudeva; Gorthi, Sai Siva

    2015-01-01

    In this work, we report a system-level integration of portable microscopy and microfluidics for the realization of optofluidic imaging flow analyzer with a throughput of 450 cells/s. With the use of a cellphone augmented with off-the-shelf optical components and custom designed microfluidics, we demonstrate a portable optofluidic imaging flow analyzer. A multiple microfluidic channel geometry was employed to demonstrate the enhancement of throughput in the context of low frame-rate imaging systems. Using the cell-phone based digital imaging flow analyzer, we have imaged yeast cells present in a suspension. By digitally processing the recorded videos of the flow stream on the cellphone, we demonstrated an automated cell viability assessment of the yeast cell population. In addition, we also demonstrate the suitability of the system for blood cell counting. PMID:26015835

  10. Microfluidic 3D cell culture: potential application for tissue-based bioassays

    PubMed Central

    Li, XiuJun (James); Valadez, Alejandra V.; Zuo, Peng; Nie, Zhihong

    2014-01-01

    Current fundamental investigations of human biology and the development of therapeutic drugs, commonly rely on two-dimensional (2D) monolayer cell culture systems. However, 2D cell culture systems do not accurately recapitulate the structure, function, physiology of living tissues, as well as highly complex and dynamic three-dimensional (3D) environments in vivo. The microfluidic technology can provide micro-scale complex structures and well-controlled parameters to mimic the in vivo environment of cells. The combination of microfluidic technology with 3D cell culture offers great potential for in vivo-like tissue-based applications, such as the emerging organ-on-a-chip system. This article will review recent advances in microfluidic technology for 3D cell culture and their biological applications. PMID:22793034

  11. Microfluidic hydrodynamic focusing based synthesis of POPC liposomes for model biological systems.

    PubMed

    Mijajlovic, M; Wright, D; Zivkovic, V; Bi, J X; Biggs, M J

    2013-04-01

    Lipid vesicles have received significant attention in areas ranging from pharmaceutical and biomedical engineering to novel materials and nanotechnology. Microfluidic-based synthesis of liposomes offers a number of advantages over the more traditional synthesis methods such as extrusion and sonication. One such microfluidic approach is microfluidic hydrodynamic focusing (MHF), which has been used to synthesize nanoparticles and vesicles of various lipids. We show here that this method can be utilized in synthesis of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles with controllable size. Since POPC is among the primary constituents of cellular membranes, this work is of direct applicability to modelling of biological systems and development of nano-containers with higher biologic compatibility for pharmaceutical and medical applications.

  12. An integrated, multiparametric flow cytometry chip using "microfluidic drifting" based three-dimensional hydrodynamic focusing.

    PubMed

    Mao, Xiaole; Nawaz, Ahmad Ahsan; Lin, Sz-Chin Steven; Lapsley, Michael Ian; Zhao, Yanhui; McCoy, J Philip; El-Deiry, Wafik S; Huang, Tony Jun

    2012-06-01

    In this work, we demonstrate an integrated, single-layer, miniature flow cytometry device that is capable of multi-parametric particle analysis. The device integrates both particle focusing and detection components on-chip, including a "microfluidic drifting" based three-dimensional (3D) hydrodynamic focusing component and a series of optical fibers integrated into the microfluidic architecture to facilitate on-chip detection. With this design, multiple optical signals (i.e., forward scatter, side scatter, and fluorescence) from individual particles can be simultaneously detected. Experimental results indicate that the performance of our flow cytometry chip is comparable to its bulky, expensive desktop counterpart. The integration of on-chip 3D particle focusing with on-chip multi-parametric optical detection in a single-layer, mass-producible microfluidic device presents a major step towards low-cost flow cytometry chips for point-of-care clinical diagnostics.

  13. Microfluidic assembly kit based on laser-cut building blocks for education and fast prototyping

    PubMed Central

    Gerber, Lukas C.; Kim, Honesty; Riedel-Kruse, Ingmar H.

    2015-01-01

    Here, we present an inexpensive rapid-prototyping method that allows researchers and children to quickly assemble multi-layered microfluidic devices from easily pre-fabricated building blocks. We developed low-cost (<$2) kits based on laser-cut acrylic building block pieces and double-sided tape that allow users to generate water droplets in oil, capture living cells, and conduct basic phototaxis experiments. We developed and tested a 90-min lesson plan with children aged 12–14 yr and provide here the instructions for teachers to replicate these experiments and lessons. All parts of the kit are easy to make or order. We propose to use such easy to fabricate kits in labs with no access to current microfluidic tools as well as in classroom environments to get exposure to the powerful techniques of microfluidics. PMID:26634013

  14. Microfluidic and Label-Free Multi-Immunosensors Based on Carbon Nanotube Microelectrodes

    NASA Astrophysics Data System (ADS)

    Tsujita, Yuichi; Maehashi, Kenzo; Matsumoto, Kazuhiko; Chikae, Miyuki; Takamura, Yuzuru; Tamiya, Eiichi

    2009-06-01

    We fabricated microfluidic and label-free multi-immunosensors by the integration of carbon nanotube (CNT)-arrayed electrodes and microchannels with pneumatic micropumps made of poly(dimethylsiloxane). In the microfluidic systems, four kinds of sample solutions were transported from each liquid inlet to microchannels using six pneumatic micropumps. As a result, two kinds of antibodies were immobilized onto different CNT electrodes using the microfluidic systems. Next, two kinds of cancer markers, prostate specific antigen and human chorionic gonadotropin in phosphate buffer solution, were simultaneously detected by differential pulse voltammetry. Therefore, microfludic multi-immunosensors based on CNT electrodes and pneumatic micropumps are useful for the development of multiplex hand-held biosensors.

  15. Microfluidic assembly kit based on laser-cut building blocks for education and fast prototyping.

    PubMed

    Gerber, Lukas C; Kim, Honesty; Riedel-Kruse, Ingmar H

    2015-11-01

    Here, we present an inexpensive rapid-prototyping method that allows researchers and children to quickly assemble multi-layered microfluidic devices from easily pre-fabricated building blocks. We developed low-cost (<$2) kits based on laser-cut acrylic building block pieces and double-sided tape that allow users to generate water droplets in oil, capture living cells, and conduct basic phototaxis experiments. We developed and tested a 90-min lesson plan with children aged 12-14 yr and provide here the instructions for teachers to replicate these experiments and lessons. All parts of the kit are easy to make or order. We propose to use such easy to fabricate kits in labs with no access to current microfluidic tools as well as in classroom environments to get exposure to the powerful techniques of microfluidics.

  16. Fabrication of a Paper-Based Microfluidic Device to Readily Determine Nitrite Ion Concentration by Simple Colorimetric Assay

    ERIC Educational Resources Information Center

    Wang, Bo; Lin, Zhiqiang; Wang, Min

    2015-01-01

    Paper-based microfluidic devices (µPAD) are a burgeoning platform of microfluidic analysis technology. The method described herein is for use in undergraduate and high school chemistry laboratories. A simple and convenient µPAD was fabricated by easy patterning of filter paper using a permanent marker pen. The usefulness of the device was…

  17. Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets

    NASA Astrophysics Data System (ADS)

    Song, Jin; Chung, Minsub; Kim, Dohyun

    2015-01-01

    We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (-5.1 °C/s) and a low freezing temperature (-14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.

  18. Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets

    SciTech Connect

    Song, Jin; Kim, Dohyun; Chung, Minsub

    2015-01-15

    We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (−5.1 °C/s) and a low freezing temperature (−14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.

  19. A Novel Microfluidic Flow Rate Detection Method Based on Surface Plasmon Resonance Temperature Imaging

    PubMed Central

    Deng, Shijie; Wang, Peng; Liu, Shengnan; Zhao, Tianze; Xu, Shanzhi; Guo, Mingjiang; Yu, Xinglong

    2016-01-01

    A novel microfluidic flow rate detection method based on surface plasmon resonance (SPR) temperature imaging is proposed. The measurement is performed by space-resolved SPR imaging of the flow induced temperature variations. Theoretical simulations and analysis were performed to demonstrate a proof of concept using this approach. Experiments were implemented and results showed that water flow rates within a wide range of tens to hundreds of μL/min could be detected. The flow rate sensor is resistant to disturbances and can be easily integrated into microfluidic lab-on-chip systems. PMID:27347960

  20. Papers Based Electrochemical Biosensors: From Test Strips to Paper-Based Microfluidics

    SciTech Connect

    Liu, Bingwen; Du, Dan; Hua, Xin; Yu, Xiao-Ying; Lin, Yuehe

    2014-05-08

    Papers based biosensors such as lateral flow test strips and paper-based microfluidic devices (or paperfluidics) are inexpensive, rapid, flexible, and easy-to-use analytical tools. An apparent trend in their detection is to interpret sensing results from qualitative assessment to quantitative determination. Electrochemical detection plays an important role in quantification. This review focuses on electrochemical (EC) detection enabled biosensors. The first part provides detailed examples in paper test strips. The second part gives an overview of paperfluidics engaging EC detections. The outlook and recommendation of future directions of EC enabled biosensors are discussed in the end.

  1. Flexible microfluidic cloth-based analytical devices using a low-cost wax patterning technique.

    PubMed

    Nilghaz, Azadeh; Wicaksono, Dedy H B; Gustiono, Dwi; Abdul Majid, Fadzilah Adibah; Supriyanto, Eko; Abdul Kadir, Mohammed Rafiq

    2012-01-07

    This paper describes the fabrication of microfluidic cloth-based analytical devices (μCADs) using a simple wax patterning method on cotton cloth for performing colorimetric bioassays. Commercial cotton cloth fabric is proposed as a new inexpensive, lightweight, and flexible platform for fabricating two- (2D) and three-dimensional (3D) microfluidic systems. We demonstrated that the wicking property of the cotton microfluidic channel can be improved by scouring in soda ash (Na(2)CO(3)) solution which will remove the natural surface wax and expose the underlying texture of the cellulose fiber. After this treatment, we fabricated narrow hydrophilic channels with hydrophobic barriers made from patterned wax to define the 2D microfluidic devices. The designed pattern is carved on wax-impregnated paper, and subsequently transferred to attached cotton cloth by heat treatment. To further obtain 3D microfluidic devices having multiple layers of pattern, a single layer of wax patterned cloth can be folded along a predefined folding line and subsequently pressed using mechanical force. All the fabrication steps are simple and low cost since no special equipment is required. Diagnostic application of cloth-based devices is shown by the development of simple devices that wick and distribute microvolumes of simulated body fluids along the hydrophilic channels into reaction zones to react with analytical reagents. Colorimetric detection of bovine serum albumin (BSA) in artificial urine is carried out by direct visual observation of bromophenol blue (BPB) colour change in the reaction zones. Finally, we show the flexibility of the novel microfluidic platform by conducting a similar reaction in a bent pinned μCAD.

  2. Thiolene and SIFEL-based Microfluidic Platforms for Liquid-Liquid Extraction

    PubMed Central

    Goyal, Sachit; Desai, Amit V.; Lewis, Robert W.; Ranganathan, David R.; Li, Hairong; Zeng, Dexing; Reichert, David E.; Kenis, Paul J.A.

    2014-01-01

    Microfluidic platforms provide several advantages for liquid-liquid extraction (LLE) processes over conventional methods, for example with respect to lower consumption of solvents and enhanced extraction efficiencies due to the inherent shorter diffusional distances. Here, we report the development of polymer-based parallel-flow microfluidic platforms for LLE. To date, parallel-flow microfluidic platforms have predominantly been made out of silicon or glass due to their compatibility with most organic solvents used for LLE. Fabrication of silicon and glass-based LLE platforms typically requires extensive use of photolithography, plasma or laser-based etching, high temperature (anodic) bonding, and/or wet etching with KOH or HF solutions. In contrast, polymeric microfluidic platforms can be fabricated using less involved processes, typically photolithography in combination with replica molding, hot embossing, and/or bonding at much lower temperatures. Here we report the fabrication and testing of microfluidic LLE platforms comprised of thiolene or a perfluoropolyether-based material, SIFEL, where the choice of materials was mainly guided by the need for solvent compatibility and fabrication amenability. Suitable designs for polymer-based LLE platforms that maximize extraction efficiencies within the constraints of the fabrication methods and feasible operational conditions were obtained using analytical modeling. To optimize the performance of the polymer-based LLE platforms, we systematically studied the effect of surface functionalization and of microstructures on the stability of the liquid-liquid interface and on the ability to separate the phases. As demonstrative examples, we report (i) a thiolene-based platform to determine the lipophilicity of caffeine, and (ii) a SIFEL-based platform to extract radioactive copper from an acidic aqueous solution. PMID:25246730

  3. Cost Effective Paper-Based Colorimetric Microfluidic Devices and Mobile Phone Camera Readers for the Classroom

    ERIC Educational Resources Information Center

    Koesdjojo, Myra T.; Pengpumkiat, Sumate; Wu, Yuanyuan; Boonloed, Anukul; Huynh, Daniel; Remcho, Thomas P.; Remcho, Vincent T.

    2015-01-01

    We have developed a simple and direct method to fabricate paper-based microfluidic devices that can be used for a wide range of colorimetric assay applications. With these devices, assays can be performed within minutes to allow for quantitative colorimetric analysis by use of a widely accessible iPhone camera and an RGB color reader application…

  4. Microfluidic paper-based biomolecule preconcentrator based on ion concentration polarization.

    PubMed

    Han, Sung Il; Hwang, Kyo Seon; Kwak, Rhokyun; Lee, Jeong Hoon

    2016-06-21

    Microfluidic paper-based analytical devices (μPADs) for molecular detection have great potential in the field of point-of-care diagnostics. Currently, a critical problem being faced by μPADs is improving their detection sensitivity. Various preconcentration processes have been developed, but they still have complicated structures and fabrication processes to integrate into μPADs. To address this issue, we have developed a novel paper-based preconcentrator utilizing ion concentration polarization (ICP) with minimal addition on lateral-flow paper. The cation selective membrane (i.e., Nafion) is patterned on adhesive tape, and this tape is then attached to paper-based channels. When an electric field is applied across the Nafion, ICP is initiated to preconcentrate the biomolecules in the paper channel. Departing from previous paper-based preconcentrators, we maintain steady lateral fluid flow with the separated Nafion layer; as a result, fluorescent dyes and proteins (FITC-albumin and bovine serum albumin) are continuously delivered to the preconcentration zone, achieving high preconcentration performance up to 1000-fold. In addition, we demonstrate that the Nafion-patterned tape can be integrated with various geometries (multiplexed preconcentrator) and platforms (string and polymer microfluidic channel). This work would facilitate integration of various ICP devices, including preconcentrators, pH/concentration modulators, and micro mixers, with steady lateral flows in paper-based platforms.

  5. Optical microfluidics

    SciTech Connect

    Kotz, K.T.; Noble, K.A.; Faris, G.W.

    2004-09-27

    We present a method for the control of small droplets based on the thermal Marangoni effect using laser heating. With this approach, droplets covering five orders of magnitude in volume ({approx}1.7 {mu}L to 14 pL), immersed in decanol, were moved on an unmodified polystyrene surface, with speeds of up to 3 mm/s. When two droplets were brought into contact, they spontaneously fused and rapidly mixed in less than 33 ms. This optically addressed microfluidic approach has many advantages for microfluidic transport, including exceptional reconfigurability, low intersample contamination, large volume range, extremely simple substrates, no electrical connections, and ready scaling to large arrays.

  6. Calcium carbonate polymorph control using droplet-based microfluidics.

    PubMed

    Yashina, Alexandra; Meldrum, Fiona; Demello, Andrew

    2012-06-01

    Calcium carbonate (CaCO(3)) is one of the most abundant minerals and of high importance in many areas of science including global CO(2) exchange, industrial water treatment energy storage, and the formation of shells and skeletons. Industrially, calcium carbonate is also used in the production of cement, glasses, paints, plastics, rubbers, ceramics, and steel, as well as being a key material in oil refining and iron ore purification. CaCO(3) displays a complex polymorphic behaviour which, despite numerous experiments, remains poorly characterised. In this paper, we report the use of a segmented-flow microfluidic reactor for the controlled precipitation of calcium carbonate and compare the resulting crystal properties with those obtained using both continuous flow microfluidic reactors and conventional bulk methods. Through combination of equal volumes of equimolar aqueous solutions of calcium chloride and sodium carbonate on the picoliter scale, it was possible to achieve excellent definition of both crystal size and size distribution. Furthermore, highly reproducible control over crystal polymorph could be realised, such that pure calcite, pure vaterite, or a mixture of calcite and vaterite could be precipitated depending on the reaction conditions and droplet-volumes employed. In contrast, the crystals precipitated in the continuous flow and bulk systems comprised of a mixture of calcite and vaterite and exhibited a broad distribution of sizes for all reaction conditions investigated.

  7. Bead-based assays for biodetection: from flow-cytometry to microfluidics

    NASA Astrophysics Data System (ADS)

    Ozanich, Richard M., Jr.; Antolick, Kathryn; Bruckner-Lea, Cynthia J.; Bunch, Kyle J.; Dockendorff, Brian P.; Grate, Jay W.; Nash, Michael A.; Tyler, Abby; Warner, Cynthia L.; Warner, Marvin G.

    2009-05-01

    The potential for the use of biological agents by terrorists is a real threat. Two approaches for antibody-based detection of biological species are described in this paper: 1) The use of microbead arrays for multiplexed flow cytometry detection of cytokines and botulinum neurotoxin simulant, and 2) a microfluidic platform for capture and separation of different size superparamagnetic nanoparticles followed by on-chip fluorescence detection of the sandwich complex. These approaches both involve the use of automated fluidic systems for trapping antibody-functionalized microbeads, which allows sample, assay reagents, and wash solutions to be perfused over a micro-column of beads, resulting in faster and more sensitive immunoassays. The automated fluidic approach resulted in up to five-fold improvements in immunoassay sensitivity/speed as compared to identical immunoassays performed in a typical manual batch mode. A second approach for implementing multiplexed bead-based immunoassays without using flow cytometry detection is currently under development. The goal of the microfluidic-based approach is to achieve rapid (<20 minutes), multiplexed (>= 3 bioagents) detection using a simple and low-cost, integrated microfluidic/optical detection platform. Using fiber-optic guided laser-induced fluorescence, assay detection limits were shown to be in the 100's of picomolar range (10's of micrograms per liter) for botulinum neurotoxin simulant without any optimization of the microfluidic device or optical detection approach.

  8. Integrated Microfluidic Devices for Automated Microarray-Based Gene Expression and Genotyping Analysis

    NASA Astrophysics Data System (ADS)

    Liu, Robin H.; Lodes, Mike; Fuji, H. Sho; Danley, David; McShea, Andrew

    Microarray assays typically involve multistage sample processing and fluidic handling, which are generally labor-intensive and time-consuming. Automation of these processes would improve robustness, reduce run-to-run and operator-to-operator variation, and reduce costs. In this chapter, a fully integrated and self-contained microfluidic biochip device that has been developed to automate the fluidic handling steps for microarray-based gene expression or genotyping analysis is presented. The device consists of a semiconductor-based CustomArray® chip with 12,000 features and a microfluidic cartridge. The CustomArray was manufactured using a semiconductor-based in situ synthesis technology. The micro-fluidic cartridge consists of microfluidic pumps, mixers, valves, fluid channels, and reagent storage chambers. Microarray hybridization and subsequent fluidic handling and reactions (including a number of washing and labeling steps) were performed in this fully automated and miniature device before fluorescent image scanning of the microarray chip. Electrochemical micropumps were integrated in the cartridge to provide pumping of liquid solutions. A micromixing technique based on gas bubbling generated by electrochemical micropumps was developed. Low-cost check valves were implemented in the cartridge to prevent cross-talk of the stored reagents. Gene expression study of the human leukemia cell line (K562) and genotyping detection and sequencing of influenza A subtypes have been demonstrated using this integrated biochip platform. For gene expression assays, the microfluidic CustomArray device detected sample RNAs with a concentration as low as 0.375 pM. Detection was quantitative over more than three orders of magnitude. Experiment also showed that chip-to-chip variability was low indicating that the integrated microfluidic devices eliminate manual fluidic handling steps that can be a significant source of variability in genomic analysis. The genotyping results showed

  9. Bead-Based Assays for Biodetection: From Flow-Cytometry to Microfluidics

    SciTech Connect

    Ozanich, Richard M.; Antolick, Kathryn C.; Bruckner-Lea, Cindy J.; Bunch, Kyle J.; Dockendorff, Brian P.; Grate, Jay W.; Nash, Michael A.; Tyler, Abby J.

    2009-05-04

    ABSTRACT The potential for the use of biological agents by terrorists is a real threat. Two approaches for detection of biological species will be described: 1) The use of microbead arrays for multiplexed flow cytometry detection of cytokines and botulinum neurotoxin simulant, and 2) a microfluidic platform for capture and separation of different size superparamagnetic nanoparticles followed by on-chip fluorescence detection of the sandwich complex. The methods and automated fluidic systems used for trapping functionalized microbeads will be described. This approach allows sample, assay reagents, and wash solutions to be perfused over a micro-column of beads, resulting in faster and more sensitive assays. The automated fluidic approach resulted in up to five-fold improvements in assay sensitivity/speed as compared to identical assays performed in a typical manual batch mode. A second approach for implementing multiplexed bead-based assays without using flow cytometry detection is currently under development. The goal of the microfluidic-based approach is to achieve rapid (<20 minutes), multiplexed (> 3 bioagents) detection using a simple and low-cost, integrated microfluidic/optical detection platform. Using fiber-optic guided laser-induced fluorescence, assay detection limits were shown to be in the 100’s of picomolar range (10’s of micrograms per liter) for botulinum neurotoxin simulant without any optimization of the microfluidic device or optical detection approach. Video taping magnetic nanoparticle capture and release was used to improve understanding of the process and revealed interesting behavior.

  10. Enzyme kinetic measurements using a droplet-based microfluidic system with a concentration gradient.

    PubMed

    Bui, Minh-Phuong Ngoc; Li, Cheng Ai; Han, Kwi Nam; Choo, Jaebum; Lee, Eun Kyu; Seong, Gi Hun

    2011-03-01

    In this paper, we propose a microfluidic device that is capable of generating a concentration gradient followed by parallel droplet formation within channels with a simple T-junction geometry. Linear concentration gradient profiles can be obtained based on fluid diffusion under laminar flow. Optimized conditions for generating a linear concentration gradient and parallel droplet formation were investigated using fluorescent dye. The concentration gradient profile under diffusive mixing was dominated by the flow rate at sample inlets, while parallel droplet formation was affected by the channel geometry at both the inlet and outlet. The microfluidic device was experimentally characterized using optimal layout and operating conditions selected through a design process. Furthermore, in situ enzyme kinetic measurements of the β-galactosidase-catalyzed hydrolysis of resorufin-β-d-galactopyranoside were performed to demonstrate the application potential of our simple, time-effective, and low sample volume microfluidic device. We expect that, in addition to enzyme kinetics, drug screening and clinical diagnostic tests can be rapidly and accurately performed using this droplet-based microfluidic system.

  11. Printed circuit technology for fabrication of plastic-based microfluidic devices.

    PubMed

    Sudarsan, Arjun P; Ugaz, Victor M

    2004-06-01

    One of the primary advantages of using plastic-based substrates for microfluidic systems is the ease with which devices can be fabricated with minimal dependence on specialized laboratory equipment. These devices are often produced using soft lithography techniques to cast replicas of a rigid mold or master incorporating a negative image of the desired surface structures. Conventional photolithographic micromachining processes are typically used to construct these masters in either thick photoresist, etched silicon, or etched glass substrates. The speed at which new masters can be produced using these techniques, however, can be relatively slow and often limits the rate at which new device designs can be built and tested. In this paper, we show that inexpensive photosensitized copper clad circuit board substrates can be employed to produce master molds using conventional printed circuit technology. This process offers the benefits of parallel fabrication associated with photolithography without the need for cleanroom facilities, thereby providing a degree of speed and simplicity that allows microfluidic master molds with well-defined and reproducible structural features to be constructed in approximately 30 min in any laboratory. Precise control of channel heights ranging from 15 to 120 microm can be easily achieved through selection of the appropriate copper layer thickness, and channel widths as small as 50 microm can be reproducibly obtained. We use these masters to produce a variety of plastic-based microfluidic channel networks and demonstrate their suitability for DNA electrophoresis and microfluidic mixing studies.

  12. Microfluidic-based metal enhanced fluorescence for capillary electrophoresis by Ag nanorod arrays

    NASA Astrophysics Data System (ADS)

    Xiao, Chenyu; Cao, Zhen; Deng, Junhong; Huang, Zhifeng; Xu, Zheng; Fu, Junxue; Yobas, Levent

    2014-06-01

    As metal nanorods show much higher metal enhanced fluorescence (MEF) than metal nanospheres, microfluidic-based MEF is first explored with Ag nanorod (ND) arrays made by oblique angle deposition. By measuring the fluorescein isothiocyanate (FITC) solution sandwiched between the Ag NDs and a piece of cover slip, the enhancement factors (EFs) are found as 3.7 ± 0.64 and 6.74 ± 2.04, for a solution thickness at 20.8 μm and 10 μm, respectively. Because of the strong plasmonic coupling between the adjacent Ag NDs, only the emission of the fluorophores present in the three-dimensional NDs array gets enhanced. Thus, the corresponding effective enhancement factors (EEFs) are revealed to be relatively close, 259 ± 92 and 340 ± 102, respectively. To demonstrate the application of MEF in microfluidic systems, a multilayer of SiO2 NDs/Ag NDs is integrated with a capillary electrophoresis device. At a microchannel depth of 10 μm, an enhancement of 6.5 fold is obtained for amino acids separation detection. These results are very encouraging and open the possibility of MEF applications for the Ag ND arrays decorated microchannels. With the miniaturization of microfluidic devices, microfluidic-based MEF by Ag ND arrays will likely find more applications with further enhancement.

  13. Entropy-based separation of yeast cells using a microfluidic system of conjoined spheres

    SciTech Connect

    Huang, Kai-Jian; Qin, S.-J. Bai, Zhong-Chen; Zhang, Xin; Mai, John D.

    2013-11-21

    A physical model is derived to create a biological cell separator that is based on controlling the entropy in a microfluidic system having conjoined spherical structures. A one-dimensional simplified model of this three-dimensional problem in terms of the corresponding effects of entropy on the Brownian motion of particles is presented. This dynamic mechanism is based on the Langevin equation from statistical thermodynamics and takes advantage of the characteristics of the Fokker-Planck equation. This mechanism can be applied to manipulate biological particles inside a microfluidic system with identical, conjoined, spherical compartments. This theoretical analysis is verified by performing a rapid and a simple technique for separating yeast cells in these conjoined, spherical microfluidic structures. The experimental results basically match with our theoretical model and we further analyze the parameters which can be used to control this separation mechanism. Both numerical simulations and experimental results show that the motion of the particles depends on the geometrical boundary conditions of the microfluidic system and the initial concentration of the diffusing material. This theoretical model can be implemented in future biophysics devices for the optimized design of passive cell sorters.

  14. Highly stable liquid metal-based pressure sensor integrated with a microfluidic channel.

    PubMed

    Jung, Taekeon; Yang, Sung

    2015-05-21

    Pressure measurement is considered one of the key parameters in microfluidic systems. It has been widely used in various fields, such as in biology and biomedical fields. The electrical measurement method is the most widely investigated; however, it is unsuitable for microfluidic systems because of a complicated fabrication process and difficult integration. Moreover, it is generally damaged by large deflection. This paper proposes a thin-film-based pressure sensor that is free from these limitations, using a liquid metal called galinstan. The proposed pressure sensor is easily integrated into a microfluidic system using soft lithography because galinstan exists in a liquid phase at room temperature. We investigated the characteristics of the proposed pressure sensor by calibrating for a pressure range from 0 to 230 kPa (R2 > 0.98) using deionized water. Furthermore, the viscosity of various fluid samples was measured for a shear-rate range of 30-1000 s(-1). The results of Newtonian and non-Newtonian fluids were evaluated using a commercial viscometer and normalized difference was found to be less than 5.1% and 7.0%, respectively. The galinstan-based pressure sensor can be used in various microfluidic systems for long-term monitoring with high linearity, repeatability, and long-term stability.

  15. Highly Stable Liquid Metal-Based Pressure Sensor Integrated with a Microfluidic Channel

    PubMed Central

    Jung, Taekeon; Yang, Sung

    2015-01-01

    Pressure measurement is considered one of the key parameters in microfluidic systems. It has been widely used in various fields, such as in biology and biomedical fields. The electrical measurement method is the most widely investigated; however, it is unsuitable for microfluidic systems because of a complicated fabrication process and difficult integration. Moreover, it is generally damaged by large deflection. This paper proposes a thin-film-based pressure sensor that is free from these limitations, using a liquid metal called galinstan. The proposed pressure sensor is easily integrated into a microfluidic system using soft lithography because galinstan exists in a liquid phase at room temperature. We investigated the characteristics of the proposed pressure sensor by calibrating for a pressure range from 0 to 230 kPa (R2 > 0.98) using deionized water. Furthermore, the viscosity of various fluid samples was measured for a shear-rate range of 30–1000 s−1. The results of Newtonian and non-Newtonian fluids were evaluated using a commercial viscometer and normalized difference was found to be less than 5.1% and 7.0%, respectively. The galinstan-based pressure sensor can be used in various microfluidic systems for long-term monitoring with high linearity, repeatability, and long-term stability. PMID:26007732

  16. Microfluidic-based metal enhanced fluorescence for capillary electrophoresis by Ag nanorod arrays.

    PubMed

    Xiao, Chenyu; Cao, Zhen; Deng, Junhong; Huang, Zhifeng; Xu, Zheng; Fu, Junxue; Yobas, Levent

    2014-06-06

    As metal nanorods show much higher metal enhanced fluorescence (MEF) than metal nanospheres, microfluidic-based MEF is first explored with Ag nanorod (ND) arrays made by oblique angle deposition. By measuring the fluorescein isothiocyanate (FITC) solution sandwiched between the Ag NDs and a piece of cover slip, the enhancement factors (EFs) are found as 3.7 ± 0.64 and 6.74 ± 2.04, for a solution thickness at 20.8 μm and 10 μm, respectively. Because of the strong plasmonic coupling between the adjacent Ag NDs, only the emission of the fluorophores present in the three-dimensional NDs array gets enhanced. Thus, the corresponding effective enhancement factors (EEFs) are revealed to be relatively close, 259 ± 92 and 340 ± 102, respectively. To demonstrate the application of MEF in microfluidic systems, a multilayer of SiO2 NDs/Ag NDs is integrated with a capillary electrophoresis device. At a microchannel depth of 10 μm, an enhancement of 6.5 fold is obtained for amino acids separation detection. These results are very encouraging and open the possibility of MEF applications for the Ag ND arrays decorated microchannels. With the miniaturization of microfluidic devices, microfluidic-based MEF by Ag ND arrays will likely find more applications with further enhancement.

  17. A multiplexed immunoassay system based upon reciprocating centrifugal microfluidics

    NASA Astrophysics Data System (ADS)

    Noroozi, Zahra; Kido, Horacio; Peytavi, Régis; Nakajima-Sasaki, Rie; Jasinskas, Algimantas; Micic, Miodrag; Felgner, Philip L.; Madou, Marc J.

    2011-06-01

    A novel, centrifugal disk-based micro-total analysis system (μTAS) for low cost and high throughput semi-automated immunoassay processing was developed. A key innovation in the disposable immunoassay disk design is in a fluidic structure that enables very efficient micro-mixing based on a reciprocating mechanism in which centrifugal acceleration acting upon a liquid element first generates and stores pneumatic energy that is then released by a reduction of the centrifugal acceleration, resulting in a reversal of direction of flow of the liquid. Through an alternating sequence of high and low centrifugal acceleration, the system reciprocates the flow of liquid within the disk to maximize incubation/hybridization efficiency between antibodies and antigen macromolecules during the incubation/hybridization stage of the assay. The described reciprocating mechanism results in a reduction in processing time and reagent consumption by one order of magnitude.

  18. A multiplexed immunoassay system based upon reciprocating centrifugal microfluidics

    PubMed Central

    Noroozi, Zahra; Kido, Horacio; Peytavi, Régis; Nakajima-Sasaki, Rie; Jasinskas, Algimantas; Micic, Miodrag; Felgner, Philip L.; Madou, Marc J.

    2011-01-01

    A novel, centrifugal disk-based micro-total analysis system (μTAS) for low cost and high throughput semi-automated immunoassay processing was developed. A key innovation in the disposable immunoassay disk design is in a fluidic structure that enables very efficient micro-mixing based on a reciprocating mechanism in which centrifugal acceleration acting upon a liquid element first generates and stores pneumatic energy that is then released by a reduction of the centrifugal acceleration, resulting in a reversal of direction of flow of the liquid. Through an alternating sequence of high and low centrifugal acceleration, the system reciprocates the flow of liquid within the disk to maximize incubation/hybridization efficiency between antibodies and antigen macromolecules during the incubation/hybridization stage of the assay. The described reciprocating mechanism results in a reduction in processing time and reagent consumption by one order of magnitude. PMID:21721711

  19. Novel developments in mobile sensing based on the integration of microfluidic devices and smartphones.

    PubMed

    Yang, Ke; Peretz-Soroka, Hagit; Liu, Yong; Lin, Francis

    2016-03-21

    Portable electronic devices and wireless communication systems enable a broad range of applications such as environmental and food safety monitoring, personalized medicine and healthcare management. Particularly, hybrid smartphone and microfluidic devices provide an integrated solution for the new generation of mobile sensing applications. Such mobile sensing based on microfluidic devices (broadly defined) and smartphones (MS(2)) offers a mobile laboratory for performing a wide range of bio-chemical detection and analysis functions such as water and food quality analysis, routine health tests and disease diagnosis. MS(2) offers significant advantages over traditional platforms in terms of test speed and control, low cost, mobility, ease-of-operation and data management. These improvements put MS(2) in a promising position in the fields of interdisciplinary basic and applied research. In particular, MS(2) enables applications to remote in-field testing, homecare, and healthcare in low-resource areas. The marriage of smartphones and microfluidic devices offers a powerful on-chip operating platform to enable various bio-chemical tests, remote sensing, data analysis and management in a mobile fashion. The implications of such integration are beyond telecommunication and microfluidic-related research and technology development. In this review, we will first provide the general background of microfluidic-based sensing, smartphone-based sensing, and their integration. Then, we will focus on several key application areas of MS(2) by systematically reviewing the important literature in each area. We will conclude by discussing our perspectives on the opportunities, issues and future directions of this emerging novel field.

  20. Novel Developments of Mobile Sensing Based on the Integration of Microfluidic Devices and Smartphone

    PubMed Central

    Yang, Ke; Peretz-Soroka, Hagit; Liu, Yong; Lin, Francis

    2016-01-01

    Portable electronic devices and wireless communication systems enable a broad range of applications such as environmental and food safety monitoring, personalized medicine and healthcare management. Particularly, hybrid smartphone and microfluidic devices provide an integrated solution for the new generation of mobile sensing applications. Such mobile sensing based on microfluidic devices (broadly defined) and smartphones (MS2) offers a mobile laboratory for performing a wide range of bio-chemical detection and analysis functions such as water and food quality analysis, routine health tests and disease diagnosis. MS2 offers significant advantages over traditional platforms in terms of test speed and control, low cost, mobility, ease-of-operation and data management. These improvements put MS2 in a promising position in the fields of interdisciplinary basic and applied research. In particular, MS2 enables applications to remote infield testing, homecare, and healthcare in low-resource areas. The marriage of smartphones and microfluidic devices offers a powerful on-chip operating platform to enable various bio-chemical tests, remote sensing, data analysis and management in a mobile fashion. The implications of such integration are beyond telecommunication and microfluidic-related research and technology development. In this review, we will first provide the general background of microfluidic-based sensing, smartphone-based sensing, and their integration. Then, we will focus on several key application areas of MS2 by systematically reviewing the important literature in each area. We will conclude by discussing our perspectives on the opportunities, issues and future directions of this emerging novel field. PMID:26899264

  1. Cellular enrichment through microfluidic fractionation based on cell biomechanical properties.

    PubMed

    Wang, Gonghao; Turbyfield, Cory; Crawford, Kaci; Alexeev, Alexander; Sulchek, Todd

    2015-10-01

    The biomechanical properties of populations of diseased cells are shown to have differences from healthy populations of cells, yet the overlap of these biomechanical properties can limit their use in disease cell enrichment and detection. We report a new microfluidic cell enrichment technology that continuously fractionates cells through differences in biomechanical properties, resulting in highly pure cellular subpopulations. Cell fractionation is achieved in a microfluidic channel with an array of diagonal ridges that are designed to segregate biomechanically distinct cells to different locations in the channel. Due to the imposition of elastic and viscous forces during cellular compression, which are a function of cell biomechanical properties including size and viscoelasticity, larger, stiffer and less viscos cells migrate parallel to the diagonal ridges and exhibit positive lateral displacement. On the other hand, smaller, softer and more viscous cells migrate perpendicular to the diagonal ridges due to circulatory flow induced by the ridges and result in negative lateral displacement. Multiple outlets are then utilized to collect cells with finer gradation of differences in cell biomechanical properties. The result is that cell fractionation dramatically improves cell separation efficiency compared to binary outputs and enables the measurement of subtle biomechanical differences within a single cell type. As a proof-of-concept demonstration, we mix two different leukemia cell lines (K562 and HL60) and utilize cell fractionation to achieve over 45-fold enhancement of cell populations, with high purity cellular enrichment (90% to 99%) of each cell line. In addition, we demonstrate cell fractionation of a single cell type (K562 cells) into subpopulations and characterize the variations of biomechanical properties of the separated cells with atomic force microscopy. These results will be beneficial to obtaining label-free separation of cellular mixtures, or to

  2. Cellular enrichment through microfluidic fractionation based on cell biomechanical properties

    PubMed Central

    Wang, Gonghao; Turbyfield, Cory; Crawford, Kaci; Alexeev, Alexander; Sulchek, Todd

    2017-01-01

    The biomechanical properties of populations of diseased cells are shown to have differences from healthy populations of cells, yet the overlap of these biomechanical properties can limit their use in disease cell enrichment and detection. We report a new microfluidic cell enrichment technology that continuously fractionates cells through differences in biomechanical properties, resulting in highly pure cellular subpopulations. Cell fractionation is achieved in a microfluidic channel with an array of diagonal ridges that are designed to segregate biomechanically distinct cells to different locations in the channel. Due to the imposition of elastic and viscous forces during cellular compression, which are a function of cell biomechanical properties including size and viscoelasticity, larger, stiffer and less viscos cells migrate parallel to the diagonal ridges and exhibit positive lateral displacement. On the other hand, smaller, softer and more viscous cells migrate perpendicular to the diagonal ridges due to circulatory flow induced by the ridges and result in negative lateral displacement. Multiple outlets are then utilized to collect cells with finer gradation of differences in cell biomechanical properties. The result is that cell fractionation dramatically improves cell separation efficiency compared to binary outputs and enables the measurement of subtle biomechanical differences within a single cell type. As a proof-of-concept demonstration, we mix two different leukemia cell lines (K562 and HL60) and utilize cell fractionation to achieve over 45-fold enhancement of cell populations, with high purity cellular enrichment (90% to 99%) of each cell line. In addition, we demonstrate cell fractionation of a single cell type (K562 cells) into subpopulations and characterize the variations of biomechanical properties of the separated cells with atomic force microscopy. These results will be beneficial to obtaining label-free separation of cellular mixtures, or to

  3. Droplet-based Biosensing for Lab-on-a-Chip, Open Microfluidics Platforms

    PubMed Central

    Dak, Piyush; Ebrahimi, Aida; Swaminathan, Vikhram; Duarte-Guevara, Carlos; Bashir, Rashid; Alam, Muhammad A.

    2016-01-01

    Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based on droplet-based microfluidics promise to integrate and automate these complex and expensive laboratory procedures onto a single chip; the cost will be further reduced if label-free biosensors could be integrated onto the LoC platforms. Here, we review some recent developments of label-free, droplet-based biosensors, compatible with “open” digital microfluidic systems. These low-cost droplet-based biosensors overcome some of the fundamental limitations of the classical sensors, enabling timely diagnosis. We identify the key challenges that must be addressed to make these sensors commercially viable and summarize a number of promising research directions. PMID:27089377

  4. A microfluidic paper-based electrochemical biosensor array for multiplexed detection of metabolic biomarkers

    NASA Astrophysics Data System (ADS)

    Zhao, Chen; Thuo, Martin M.; Liu, Xinyu

    2013-10-01

    Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat) for signal readout. The biosensor array can detect several analytes in a sample solution and produce multiple measurements for each analyte from a single run. Using the device, we demonstrate simultaneous detection of glucose, lactate and uric acid in urine, with analytical performance comparable to that of the existing commercial and paper-based platforms. The paper-based biosensor array and its electrochemical reader will enable the acquisition of high-density, statistically meaningful diagnostic information at the point of care in a rapid and cost-efficient way.

  5. A microfluidic paper-based electrochemical biosensor array for multiplexed detection of metabolic biomarkers

    PubMed Central

    Zhao, Chen; Thuo, Martin M; Liu, Xinyu

    2013-01-01

    Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat) for signal readout. The biosensor array can detect several analytes in a sample solution and produce multiple measurements for each analyte from a single run. Using the device, we demonstrate simultaneous detection of glucose, lactate and uric acid in urine, with analytical performance comparable to that of the existing commercial and paper-based platforms. The paper-based biosensor array and its electrochemical reader will enable the acquisition of high-density, statistically meaningful diagnostic information at the point of care in a rapid and cost-efficient way. PMID:27877606

  6. Droplet-based Biosensing for Lab-on-a-Chip, Open Microfluidics Platforms.

    PubMed

    Dak, Piyush; Ebrahimi, Aida; Swaminathan, Vikhram; Duarte-Guevara, Carlos; Bashir, Rashid; Alam, Muhammad A

    2016-04-14

    Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based on droplet-based microfluidics promise to integrate and automate these complex and expensive laboratory procedures onto a single chip; the cost will be further reduced if label-free biosensors could be integrated onto the LoC platforms. Here, we review some recent developments of label-free, droplet-based biosensors, compatible with "open" digital microfluidic systems. These low-cost droplet-based biosensors overcome some of the fundamental limitations of the classical sensors, enabling timely diagnosis. We identify the key challenges that must be addressed to make these sensors commercially viable and summarize a number of promising research directions.

  7. Development and Fabrication of Nanoporous Silicon-based Bioreactors within a Microfluidic Chip

    SciTech Connect

    Siuti, Piro; Choi, Chang Kyoung; Doktycz, Mitchel John; Retterer, Scott T

    2010-01-01

    Multi-scale lithography and cryogenic deep reactive ion etching techniques were used to create ensembles of nanoporous, picoliter volume, reaction vessels within a microfluidic system. The fabrication of these vessels is described and how this process can be used to tailor vessel porosity by controlling the width of slits that constitute the vessel pores is demonstrated. Control of pore size allows the containment of nucleic acids and enzymes that are the foundation of biochemical reaction systems, while allowing smaller reaction constituents to traverse the container membrane and continuously supply the reaction. In this work, a 5.4kB DNA plasmid was retained within the reaction vessels and labeled under microfluidic control with ethidium bromide as an initial proof-of-principle. Subsequently, a coupled enzyme reaction, in which glucose oxidase and horseradish peroxidase were contained and fed with a substrate solution of glucose and Amplex Red to produce fluorescent Resorufin, was carried out under microfluidic control and monitored using fluorescent microscopy. The fabrication techniques presented are broadly applicable and can be adapted to produce devices in which a variety of high aspect ratio, nanoporous silicon structures can be integrated within a microfluidic network. The devices shown here are amenable to being scaled in number and organized to implement more complex reaction systems for applications in sensing and production of biologically based therapeutics as well as fundamental studies of biological reaction systems.

  8. Microfluidic flowmeter based on micro "hot-wire" sandwiched Fabry-Perot interferometer.

    PubMed

    Li, Ying; Yan, Guofeng; Zhang, Liang; He, Sailing

    2015-04-06

    We present a compact microfluidic flowmeter based on Fabry-Perot interferometer (FPI). The FPI was composed by a pair of fiber Bragg grating reflectors and a micro Co(2+)-doped optical fiber cavity, acting as a "hot-wire" sensor. Microfluidic channels made from commercial silica capillaries were integrated with the FPIs on a chip to realize flow-rate sensing system. By utilizing a tunable pump laser with wavelength of 1480 nm, the proposed flowmeter was experimentally demonstrated. The flow rate of the liquid sample is determined by the induced resonance wavelength shift of the FPI. The effect of the pump power, microfluidic channel scale and temperature on the performance of our flowmeter was investigated. The dynamic response was also measured under different flow-rate conditions. The experimental results achieve a sensitivity of 70 pm/(μL/s), a dynamic range up to 1.1 μL/s and response time in the level of seconds, with a spatial resolution ~200 μm. Such good performance renders the sensor a promising supplementary component in microfluidic biochemical sensing system. Furthermore, simulation modal was built up to analyze the heat distribution of the "hot-wire" cavity and optimize the FPI structure as well.

  9. Open-channel, water-in-oil emulsification in paper-based microfluidic devices.

    PubMed

    Li, C; Boban, M; Tuteja, A

    2017-04-11

    Open-channel microfluidic devices have shown great potential in achieving a high degree of fluid control, at relatively low-cost, while enabling the opportunity for rapid fabrication. However, thus far, work in open channel microfluidics has largely focused on controlling the flow of water or other aqueous solutions. In this work we present new open channel microfluidic devices based on surfaces with patterned wettabilty that are capable of controlling the flow of virtually all high and low surface tension liquids. The fabricated open channel devices are capable of constraining a variety of low surface tension oils at high enough flow rates to enable, for the first time, water-in-oil microfluidic emulsification in an open channel device. By changing the flow rates for both the aqueous (dispersed) and organic (continuous) phases, we show that it is possible to vary the size of the emulsified droplets produced in the open channel device. Finally, we utilized the fabricated devices to synthesize relatively monodisperse, hydrogel microparticles that could incorporate a drug molecule. We also investigated the drug release characteristics of the fabricated particles.

  10. Single-cell analysis and sorting using droplet-based microfluidics

    PubMed Central

    Mazutis, Linas; Gilbert, John; Ung, W Lloyd; Weitz, David A; Griffiths, Andrew D; Heyman, John A

    2014-01-01

    We present a droplet-based microfluidics protocol for high-throughput analysis and sorting of single cells. compartmentalization of single cells in droplets enables the analysis of proteins released from or secreted by cells, thereby overcoming one of the major limitations of traditional flow cytometry and fluorescence-activated cell sorting. as an example of this approach, we detail a binding assay for detecting antibodies secreted from single mouse hybridoma cells. secreted antibodies are detected after only 15 min by co-compartmentalizing single mouse hybridoma cells, a fluorescent probe and single beads coated with anti-mouse IgG antibodies in 50-pl droplets. the beads capture the secreted antibodies and, when the captured antibodies bind to the probe, the fluorescence becomes localized on the beads, generating a clearly distinguishable fluorescence signal that enables droplet sorting at ~200 Hz as well as cell enrichment. the microfluidic system described is easily adapted for screening other intracellular, cell-surface or secreted proteins and for quantifying catalytic or regulatory activities. In order to screen ~1 million cells, the microfluidic operations require 2–6 h; the entire process, including preparation of microfluidic devices and mammalian cells, requires 5–7 d. PMID:23558786

  11. Low cost microfluidic device based on cotton threads for electroanalytical application.

    PubMed

    Agustini, Deonir; Bergamini, Márcio F; Marcolino-Junior, Luiz Humberto

    2016-01-21

    Microfluidic devices are an interesting alternative for performing analytical assays, due to the speed of analyses, reduced sample, reagent and solvent consumption and less waste generation. However, the high manufacturing costs still prevent the massive use of these devices worldwide. Here, we present the construction of a low cost microfluidic thread-based electroanalytical device (μTED), employing extremely cheap materials and a manufacturing process free of equipment. The microfluidic channels were built with cotton threads and the estimated cost per device was only $0.39. The flow of solutions (1.12 μL s(-1)) is generated spontaneously due to the capillary forces, eliminating the use of any pumping system. To demonstrate the analytical performance of the μTED, a simultaneous determination of acetaminophen (ACT) and diclofenac (DCF) was performed by multiple pulse amperometry (MPA). A linear dynamic range (LDR) of 10 to 320 μmol L(-1) for both species, a limit of detection (LOD) and a limit of quantitation (LOQ) of 1.4 and 4.7 μmol L(-1) and 2.5 and 8.3 μmol L(-1) for ACT and DCF, respectively, as well as an analytical frequency of 45 injections per hour were reached. Thus, the proposed device has shown potential to extend the use of microfluidic analytical devices, due to its simplicity, low cost and good analytical performance.

  12. Microfluidic delivery of small molecules into mammalian cells based on hydrodynamic focusing.

    PubMed

    Wang, Fen; Wang, Hao; Wang, Jun; Wang, Hsiang-Yu; Rummel, Peter L; Garimella, Suresh V; Lu, Chang

    2008-05-01

    Microfluidics-based cell assays offer high levels of automation and integration, and allow multiple assays to be run in parallel, based on reduced sample volumes. These characteristics make them attractive for studies associated with drug discovery. Controlled delivery of drug molecules or other exogenous materials into cells is a critical issue that needs to be addressed before microfluidics can serve as a viable platform for drug screening and studies. In this study, we report the application of hydrodynamic focusing for controlled delivery of small molecules into cells immobilized on the substrate of a microfluidic device. We delivered calcein AM which was permeant to the cell membrane into cells, and monitored its enzymatic conversion into fluorescent calcein during and after the delivery. Different ratios of the sample flow to the side flow were tested to determine how the conditions of hydrodynamic focusing affected the delivery. A 3D numerical model was developed to help understand the fluid flow, molecular diffusion due to hydrodynamic focusing in the microfluidic channel. The results from the simulation indicated that the calcein AM concentration on the outer surface of a cell was determined by the conditions of hydrodynamic focusing. By comparing the results from the simulation with those from the experiment, we found that the calcein AM concentration on the cell outer surface correlated very well with the amount of the molecules delivered into the cell. This suggests that hydrodynamic focusing provides an effective way for potentially quantitative delivery of exogenous molecules into cells at the single cell or subcellular level. We expect that our technique will pave the way to high-throughput drug screening and delivery on a microfluidic platform.

  13. A highly efficient microfluidic nano biochip based on nanostructured nickel oxide

    NASA Astrophysics Data System (ADS)

    Ali, Md. Azahar; Solanki, Pratima R.; Patel, Manoj K.; Dhayani, Hemant; Agrawal, Ved Varun; John, Renu; Malhotra, Bansi D.

    2013-03-01

    We present results of the studies relating to fabrication of a microfluidic biosensor chip based on nickel oxide nanorods (NRs-NiO) that is capable of directly measuring the concentration of total cholesterol in human blood through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of cholesterol present in buffer solutions at clinically relevant concentrations. The microfluidic channel has been fabricated onto a nickel oxide nanorod-based electrode co-immobilized with cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) that serves as the working electrode. Bare indium tin oxide served as the counter electrode. A Ag/AgCl wire introduced to the outlet of the microchannel acts as a reference electrode. The fabricated NiO nanorod-based electrode has been characterized using X-ray diffraction, Raman spectroscopy, HR-TEM, FT-IR, UV-visible spectroscopy and electrochemical techniques. The presented NRs-NiO based microfluidic sensor exhibits linearity in the range of 1.5-10.3 mM, a high sensitivity of 0.12 mA mM-1 cm-2 and a low value of 0.16 mM of the Michaelis-Menten constant (Km).We present results of the studies relating to fabrication of a microfluidic biosensor chip based on nickel oxide nanorods (NRs-NiO) that is capable of directly measuring the concentration of total cholesterol in human blood through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of cholesterol present in buffer solutions at clinically relevant concentrations. The microfluidic channel has been fabricated onto a nickel oxide nanorod-based electrode co-immobilized with cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) that serves as the working electrode. Bare indium tin oxide served as the counter electrode. A Ag/AgCl wire introduced to the outlet of the microchannel acts as a reference electrode. The fabricated NiO nanorod-based

  14. Expanding the available assays: adapting and validating In-Cell Westerns in microfluidic devices for cell-based assays.

    PubMed

    Paguirigan, Amy L; Puccinelli, John P; Su, Xiaojing; Beebe, David J

    2010-10-01

    Microfluidic methods for cellular studies can significantly reduce costs due to reduced reagent and biological specimen requirements compared with many traditional culture techniques. However, current types of readouts are limited and this lack of suitable readouts for microfluidic cultures has significantly hindered the application of microfluidics for cell-based assays. The In-Cell Western (ICW) technique uses quantitative immunocytochemistry and a laser scanner to provide an in situ measure of protein quantities in cells grown in microfluidic channels of arbitrary geometries. The use of ICWs in microfluidic channels was validated by a detailed comparison with current macroscale methods and shown to have excellent correlation. Transforming growth factor-β-induced epithelial-to-mesenchymal transition of an epithelial cell line was used as an example for further validation of the technique as a readout for soluble-factor-based assays performed in high-throughput microfluidic channels. The use of passive pumping for sample delivery and laser scanning for analysis opens the door to high-throughput quantitative microfluidic cell-based assays that integrate seamlessly with existing high-throughput infrastructure.

  15. Photoelectrochemical sensor for pentachlorophenol on microfluidic paper-based analytical device based on the molecular imprinting technique.

    PubMed

    Sun, Guoqiang; Wang, Panpan; Ge, Shenguang; Ge, Lei; Yu, Jinghua; Yan, Mei

    2014-06-15

    Combining microfluidic paper-based analytical device (μ-PAD) and the molecular imprinting technique, a visible light photoelectrochemical (PEC) sensing platform for the detection of pentachlorophenol (PCP) was established on gold nanoparticles (AuNPs) decorated paper working electrode using polypyrrole-functionalized ZnO nanoparticles. Ascorbic acid (AA) was exploited as an efficient and nontoxic electron donor for scavenging photogenerated holes under mild solution medium and facilitating the generation of stable photocurrent. The microfluidic molecular imprinted polymer-based PEC analytical origami device is developed for the detection of PCP in the linear range from 0.01 ng mL(-1) to 100 ng mL(-1) with a low detection limit of 4 pg mL(-1). This disposable microfluidic PEC origami device would provide a new platform for sensitive, specific, and multiplex assay in public health, environmental monitoring, and the developing world.

  16. Magnetic-Field-Assisted Fabrication and Manipulation of Nonspherical Polymer Particles in Ferrofluid-Based Droplet Microfluidics.

    PubMed

    Zhu, Taotao; Cheng, Rui; Sheppard, Gareth R; Locklin, Jason; Mao, Leidong

    2015-08-11

    We report a novel magnetic-field-assisted method for the fabrication and manipulation of nonspherical polymer particles within a ferrofluid-based droplet microfluidic device. Shape control and chain assembly of droplets with tunable lengths have been achieved.

  17. A nanostructured aluminum oxide-based microfluidic device for enhancing immunoassay's fluorescence and detection sensitivity.

    PubMed

    Li, Xiang; Yin, Haocheng; Que, Long

    2014-10-01

    A nanostructured aluminum oxide (NAO)-based fluorescence biosensing platform with a programmable sample delivery microfluidic interface is reported. The NAO-based fluorescence sensor can tremendously enhance the fluorescence signals, typically up to 100 × or more, over the glass substrate. The programmable sample delivery microfluidic interface, which is integrated with the NAO-based sensors, can automatically generate and deliver a series of different concentrations of the biological samples to each individual sensor. Hence it can facilitate the fluorescence-based biodetection and analysis for high throughput applications. Using Protein A and fluorophore-labeled Immunoglobulin G (IgG) as models, the binding between them on this platform have been demonstrated. It has been shown that the IgG of programmable concentrations can be delivered to individual sensor using the microfluidic interface and confirmed by the fluorescence images. Using current NAO-based fluorescence sensors without any optimization, the detectable concentration of IgG can be as low as 20 pg/mm(2) using a conventional fluorescence microscope. Due to its inexpensive fabrication process, this technology could provide a disposable technical platform for fluorescence-based sensing and analysis.

  18. Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms.

    PubMed

    Clausell-Tormos, Jenifer; Lieber, Diana; Baret, Jean-Christophe; El-Harrak, Abdeslam; Miller, Oliver J; Frenz, Lucas; Blouwolff, Joshua; Humphry, Katherine J; Köster, Sarah; Duan, Honey; Holtze, Christian; Weitz, David A; Griffiths, Andrew D; Merten, Christoph A

    2008-05-01

    High-throughput, cell-based assays require small sample volumes to reduce assay costs and to allow for rapid sample manipulation. However, further miniaturization of conventional microtiter plate technology is problematic due to evaporation and capillary action. To overcome these limitations, we describe droplet-based microfluidic platforms in which cells are grown in aqueous microcompartments separated by an inert perfluorocarbon carrier oil. Synthesis of biocompatible surfactants and identification of gas-permeable storage systems allowed human cells, and even a multicellular organism (C. elegans), to survive and proliferate within the microcompartments for several days. Microcompartments containing single cells could be reinjected into a microfluidic device after incubation to measure expression of a reporter gene. This should open the way for high-throughput, cell-based screening that can use >1000-fold smaller assay volumes and has approximately 500x higher throughput than conventional microtiter plate assays.

  19. Biocompatible fluorinated polyglycerols for droplet microfluidics as an alternative to PEG-based copolymer surfactants.

    PubMed

    Wagner, Olaf; Thiele, Julian; Weinhart, Marie; Mazutis, Linas; Weitz, David A; Huck, Wilhelm T S; Haag, Rainer

    2016-01-07

    In droplet-based microfluidics, non-ionic, high-molecular weight surfactants are required to stabilize droplet interfaces. One of the most common structures that imparts stability as well as biocompatibility to water-in-oil droplets is a triblock copolymer surfactant composed of perfluoropolyether (PFPE) and polyethylene glycol (PEG) blocks. However, the fast growing applications of microdroplets in biology would benefit from a larger choice of specialized surfactants. PEG as a hydrophilic moiety, however, is a very limited tool in surfactant modification as one can only vary the molecular weight and chain-end functionalization. In contrast, linear polyglycerol offers further side-chain functionalization to create custom-tailored, biocompatible droplet interfaces. Herein, we describe the synthesis and characterization of polyglycerol-based triblock surfactants with tailored side-chain composition, and exemplify their application in cell encapsulation and in vitro gene expression studies in droplet-based microfluidics.

  20. Design and fabrication of polymer-based microfluidic platforms for BioMEMS applications

    NASA Astrophysics Data System (ADS)

    Lai, Siyi

    The goal of this study is to design and fabricate polymer microfluidic devices for BioMEMS applications. The emphasis is on the design of microfluidic functions and the development of a new packaging technique. A microfluidic platform was designed on a compact disk (CD) for medical diagnostics, which includes functions such as pumping, valving, sample/reagent loading, mixing, metering, and separation. The fluid propulsion was based on the centrifugal force. A passive capillary valve, which is based on a pressure barrier that develops when the cross-section of the capillary expands abruptly, was used to control the fluid flow. Micromixing was achieved by impinging mixing and bend-induced vortices. Integration of these microfluidic functions was applied in a two-point calibration system for medical diagnostics and a cascade micromixer for protein reconstitution. A specific application was for enzyme-linked immunosorbent assays (ELISA). It has been demonstrated successfully to realize the necessary microfluidic functions for the ELISA process on a CD. The preliminary analysis of rat IgG from hybridoma culture showed that the microchip-based ELISA has the same detection range as the conventional method on the 96-well microtiter plate, and has advantages such as less reagent consumption and shorter assay time over the conventional one. A new resin-gas injection technique was developed for bonding and surface modification of polymer microfluidic devices. This method can easily bond biochips with complex flow patterns. By adding surface modification agents, the interfacial free energy of the substrate with water can be controlled. Local modification of the channel surface can also be achieved through sequential resin-gas injection in conjunction with the masking technique. For application, this technique was used to form a layer of dry monolithic stationary hydrogel on the walls of a microchannel, serving as a sieving material for electrophoresis separation of DNA

  1. A laser-based technology for fabricating a soda-lime glass based microfluidic device for circulating tumour cell capture.

    PubMed

    Nieto, Daniel; Couceiro, Ramiro; Aymerich, Maria; Lopez-Lopez, Rafael; Abal, Miguel; Flores-Arias, María Teresa

    2015-10-01

    We developed a laser-based technique for fabricating microfluidic microchips on soda-lime glass substrates. The proposed methodology combines a laser direct writing, as a manufacturing tool for the fabrication of the microfluidics structures, followed by a post-thermal treatment with a CO2 laser. This treatment will allow reshaping and improving the morphological (roughness) and optical qualities (transparency) of the generated microfluidics structures. The use of lasers commonly implemented for material processing makes this technique highly competitive when compared with other glass microstructuring approaches. The manufactured chips were tested with tumour cells (Hec 1A) after being functionalized with an epithelial cell adhesion molecule (EpCAM) antibody coating. Cells were successfully arrested on the pillars after being flown through the device giving our technology a translational application in the field of cancer research.

  2. Development of a Plastic-Based Microfluidic Immunosensor Chip for Detection of H1N1 Influenza

    PubMed Central

    Lee, Kyoung G.; Lee, Tae Jae; Jeong, Soon Woo; Choi, Ho Woon; Heo, Nam Su; Park, Jung Youn; Park, Tae Jung; Lee, Seok Jae

    2012-01-01

    Lab-on-a-chip can provide convenient and accurate diagnosis tools. In this paper, a plastic-based microfluidic immunosensor chip for the diagnosis of swine flu (H1N1) was developed by immobilizing hemagglutinin antigen on a gold surface using a genetically engineered polypeptide. A fluorescent dye-labeled antibody (Ab) was used for quantifying the concentration of Ab in the immunosensor chip using a fluorescent technique. For increasing the detection efficiency and reducing the errors, three chambers and three microchannels were designed in one microfluidic chip. This protocol could be applied to the diagnosis of other infectious diseases in a microfluidic device. PMID:23112630

  3. A low-cost thin layer coulometric microfluidic device based on an ion-selective membrane for calcium determination.

    PubMed

    Dorokhin, Denis; Crespo, Gastón A; Afshar, Majid Ghahraman; Bakker, Eric

    2014-01-07

    A prototype of a low-cost and easy-to-use thin layer coulometric microfluidic device based on an ion-selective membrane for calcium detection is described. The microfluidic device was fabricated and consequently assembled with inexpensive materials without using sophisticated and centralized fabrication laboratory facilities. The linear range of the device is found to be 10-100 μM for a 60 s current integration time. Preliminary validations showed that the microfluidic device is suitable for the quantification of calcium in mineral water.

  4. Development of a fast thermal response microfluidic system using liquid metal

    NASA Astrophysics Data System (ADS)

    Gao, Meng; Gui, Lin

    2016-07-01

    Room temperature liquid metal gallium alloy has been widely used in many micro-electromechanical systems applications, such as on-chip electrical microheaters, micro temperature sensors, micro pumps and so on. Injecting liquid metal into microchannels can provide a simple, rapid, low-cost but efficient way to integrate these elements in microfluidic chips with high accuracy. The liquid metal-filled microstructures can be designed in any shape and easily integrated into microfluidic chips. In this paper, an on-chip liquid metal-based thermal microfluidic system is proposed for quick temperature control at the microscale. The micro system utilizes just one microfluidic chip as a basic working platform, which has liquid metal-based on-chip heaters, temperature sensors and electroosmotic flow pumps. Under the comprehensive control of these elements, the micro system can quickly change the temperature of a target fluid in the microfluidic chip. These liquid metal-based on-chip elements are very helpful for the fabrication and miniaturization of the microfluidic chip. In this paper, deionized water is used to test the temperature control performance of the thermal microfluidic system. According to the experimental results, the micro system can efficiently control the temperature of water ranging from 28 °C to 90 °C. The thermal microfluidic system has great potential for use in many microfluidic applications, such as on-chip polymerase chain reaction, temperature gradient focusing, protein crystallization and chemical synthesis.

  5. Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays.

    PubMed

    Fernandes, Syrena C; Wilson, Daniel J; Mace, Charles R

    2017-03-09

    Paper wicks fluids autonomously due to capillary action. By patterning paper with hydrophobic barriers, the transport of fluids can be controlled and directed within a layer of paper. Moreover, stacking multiple layers of patterned paper creates sophisticated three-dimensional microfluidic networks that can support the development of analytical and bioanalytical assays. Paper-based microfluidic devices are inexpensive, portable, easy to use, and require no external equipment to operate. As a result, they hold great promise as a platform for point-of-care diagnostics. In order to properly evaluate the utility and analytical performance of paper-based devices, suitable methods must be developed to ensure their manufacture is reproducible and at a scale that is appropriate for laboratory settings. In this manuscript, a method to fabricate a general device architecture that can be used for paper-based immunoassays is described. We use a form of additive manufacturing (multi-layer lamination) to prepare devices that comprise multiple layers of patterned paper and patterned adhesive. In addition to demonstrating the proper use of these three-dimensional paper-based microfluidic devices with an immunoassay for human chorionic gonadotropin (hCG), errors in the manufacturing process that may result in device failures are discussed. We expect this approach to manufacturing paper-based devices will find broad utility in the development of analytical applications designed specifically for limited-resource settings.

  6. Development of a Microfluidics-Based Intracochlear Drug Delivery Device

    PubMed Central

    Sewell, William F.; Borenstein, Jeffrey T.; Chen, Zhiqiang; Fiering, Jason; Handzel, Ophir; Holmboe, Maria; Kim, Ernest S.; Kujawa, Sharon G.; McKenna, Michael J.; Mescher, Mark M.; Murphy, Brian; Leary Swan, Erin E.; Peppi, Marcello; Tao, Sarah

    2009-01-01

    Background Direct delivery of drugs and other agents into the inner ear will be important for many emerging therapies, including the treatment of degenerative disorders and guiding regeneration. Methods We have taken a microfluidics/MEMS (MicroElectroMechanical Systems) technology approach to develop a fully implantable reciprocating inner-ear drug-delivery system capable of timed and sequenced delivery of agents directly into perilymph of the cochlea. Iterations of the device were tested in guinea pigs to determine the flow characteristics required for safe and effective delivery. For these tests, we used the glutamate receptor blocker DNQX, which alters auditory nerve responses but not cochlear distortion product otoacoustic emissions. Results We have demonstrated safe and effective delivery of agents into the scala tympani. Equilibration of the drug in the basal turn occurs rapidly (within tens of minutes) and is dependent on reciprocating flow parameters. Conclusion We have described a prototype system for the direct delivery of drugs to the inner ear that has the potential to be a fully implantable means for safe and effective treatment of hearing loss and other diseases. PMID:19923811

  7. Integrated microspectrometer for fluorescence based analysis in a microfluidic format.

    PubMed

    Hu, Zhixiong; Glidle, Andrew; Ironside, Charles N; Sorel, Marc; Strain, Michael J; Cooper, Jon; Yin, Huabing

    2012-08-21

    We have demonstrated a monolithic integrated arrayed waveguide grating (AWG) microspectrometer microfluidic platform capable of fluorescence spectroscopic analysis. The microspectrometer in this proof of concept study has a small (1 cm × 1 cm) footprint and 8 output channels centred on different wavelengths. We show that the signals from the output channels detected on a camera chip can be used to recreate the complete fluorescence spectrum of an analyte. By making fluorescence measurements of (i) mixed quantum dot solutions, (ii) an organic fluorophore (Cy5) and (iii) the propidium iodide (PI)-DNA assay, we illustrate the unique advantages of the AWG platform for simultaneous, quantitative multiplex detection and its capability to detect small spectroscopic shifts. Although the current system is designed for fluorescence spectroscopic analysis, in principle, it can be implemented for other types of analysis, such as Raman spectroscopy. Fabricated using established semiconductor industry methods, this miniaturised platform holds great potential to create a handheld, low cost biosensor with versatile detection capability.

  8. Recent trends in nanomaterial-based microanalytical systems for the speciation of trace elements: A critical review.

    PubMed

    Tseng, Wei-Chang; Hsu, Keng-Chang; Shiea, Christopher Stephen; Huang, Yeou-Lih

    2015-07-16

    Trace element speciation in biomedical and environmental science has gained increasing attention over the past decade as researchers have begun to realize its importance in toxicological studies. Several nanomaterials, including titanium dioxide nanoparticles (nano-TiO2), carbon nanotubes (CNTs), and magnetic nanoparticles (MNPs), have been used as sorbents to separate and preconcentrate trace element species prior to detection through mass spectrometry or optical spectroscopy. Recently, these nanomaterial-based speciation techniques have been integrated with microfluidics to minimize sample and reagent consumption and simplify analyses. This review provides a critical look into the present state and recent applications of nanomaterial-based microanalytical systems in the speciation of trace elements. The adsorption and preconcentration efficiencies, sample volume requirements, and detection limits of these nanomaterial-based speciation techniques are detailed, and their applications in environmental and biological analyses are discussed. Current perspectives and future trends into the increasing use of nanomaterial-based microfluidic techniques for trace element speciation are highlighted.

  9. Paper-based microfluidic approach for surface-enhanced raman spectroscopy and highly reproducible detection of proteins beyond picomolar concentration.

    PubMed

    Saha, Arindam; Jana, Nikhil R

    2015-01-14

    Although microfluidic approach is widely used in various point of care diagnostics, its implementation in surface enhanced Raman spectroscopy (SERS)-based detection is challenging. This is because SERS signal depends on plasmonic nanoparticle aggregation induced generation of stable electromagnetic hot spots and in currently available microfluidic platform this condition is difficult to adapt. Here we show that SERS can be adapted using simple paper based microfluidic system where both the plasmonic nanomaterials and analyte are used in mobile phase. This approach allows analyte induced controlled particle aggregation and electromagnetic hot spot generation inside the microfluidic channel with the resultant SERS signal, which is highly reproducible and sensitive. This approach has been used for reproducible detection of protein in the pico to femtomolar concentration. Presented approach is simple, rapid, and cost-effective, and requires low sample volume. Method can be extended for SERS-based detection of other biomolecules.

  10. Aptamer-Based Microfluidic Electrochemical Biosensor for Monitoring Cell-Secreted Trace Cardiac Biomarkers.

    PubMed

    Shin, Su Ryon; Zhang, Yu Shrike; Kim, Duck-Jin; Manbohi, Ahmad; Avci, Huseyin; Silvestri, Antonia; Aleman, Julio; Hu, Ning; Kilic, Tugba; Keung, Wendy; Righi, Martina; Assawes, Pribpandao; Alhadrami, Hani A; Li, Ronald A; Dokmeci, Mehmet R; Khademhosseini, Ali

    2016-10-04

    Continual monitoring of secreted biomarkers from organ-on-a-chip models is desired to understand their responses to drug exposure in a noninvasive manner. To achieve this goal, analytical methods capable of monitoring trace amounts of secreted biomarkers are of particular interest. However, a majority of existing biosensing techniques suffer from limited sensitivity, selectivity, stability, and require large working volumes, especially when cell culture medium is involved, which usually contains a plethora of nonspecific binding proteins and interfering compounds. Hence, novel analytical platforms are needed to provide noninvasive, accurate information on the status of organoids at low working volumes. Here, we report a novel microfluidic aptamer-based electrochemical biosensing platform for monitoring damage to cardiac organoids. The system is scalable, low-cost, and compatible with microfluidic platforms easing its integration with microfluidic bioreactors. To create the creatine kinase (CK)-MB biosensor, the microelectrode was functionalized with aptamers that are specific to CK-MB biomarker secreted from a damaged cardiac tissue. Compared to antibody-based sensors, the proposed aptamer-based system was highly sensitive, selective, and stable. The performance of the sensors was assessed using a heart-on-a-chip system constructed from human embryonic stem cell-derived cardiomyocytes following exposure to a cardiotoxic drug, doxorubicin. The aptamer-based biosensor was capable of measuring trace amounts of CK-MB secreted by the cardiac organoids upon drug treatments in a dose-dependent manner, which was in agreement with the beating behavior and cell viability analyses. We believe that, our microfluidic electrochemical biosensor using aptamer-based capture mechanism will find widespread applications in integration with organ-on-a-chip platforms for in situ detection of biomarkers at low abundance and high sensitivity.

  11. The use of carrier RNA to enhance DNA extraction from microfluidic-based silica monoliths.

    PubMed

    Shaw, Kirsty J; Thain, Lauren; Docker, Peter T; Dyer, Charlotte E; Greenman, John; Greenway, Gillian M; Haswell, Stephen J

    2009-10-12

    DNA extraction was carried out on silica-based monoliths within a microfluidic device. Solid-phase DNA extraction methodology was applied in which the DNA binds to silica in the presence of a chaotropic salt, such as guanidine hydrochloride, and is eluted in a low ionic strength solution, such as water. The addition of poly-A carrier RNA to the chaotropic salt solution resulted in a marked increase in the effective amount of DNA that could be recovered (25ng) compared to the absence of RNA (5ng) using the silica-based monolith. These findings confirm that techniques utilising nucleic acid carrier molecules can enhance DNA extraction methodologies in microfluidic applications.

  12. Prediction and validation of concentration gradient generation in a paper-based microfluidic channel

    NASA Astrophysics Data System (ADS)

    Jang, Ilhoon; Kim, Gang-June; Song, Simon

    2016-11-01

    A paper-based microfluidic channel has obtained attention as a diagnosis device that can implement various chemical or biological reactions. With benefits of thin, flexible, and strong features of paper devices, for example, it is often utilized for cell culture where controlling oxygen, nutrients, metabolism, and signaling molecules gradient affects the growth and movement of the cells. Among various features of paper-based microfluidic devices, we focus on establishment of concentration gradient in a paper channel. The flow is subject to dispersion and capillary effects because a paper is a porous media. In this presentation, we describe facile, fast and accurate method of generating a concentration gradient by using flow mixing of different concentrations. Both theoretical prediction and experimental validation are discussed along with inter-diffusion characteristics of porous flows. This work was supported by the National Research Foundation of Korea(NRF) Grant funded by the Korea government(MSIP) (No. 2016R1A2B3009541).

  13. Finite Element Model of Oxygen Transport for the Design of Geometrically Complex Microfluidic Devices Used in Biological Studies

    PubMed Central

    Fraser, Graham M.; Goldman, Daniel; Ellis, Christopher G.

    2016-01-01

    Red blood cells play a crucial role in the local regulation of oxygen supply in the microcirculation through the oxygen dependent release of ATP. Since red blood cells serve as an oxygen sensor for the circulatory system, the dynamics of ATP release determine the effectiveness of red blood cells to relate the oxygen levels to the vessels. Previous work has focused on the feasibility of developing a microfluidic system to measure the dynamics of ATP release. The objective was to determine if a steep oxygen gradient could be developed in the channel to cause a rapid decrease in hemoglobin oxygen saturation in order to measure the corresponding levels of ATP released from the red blood cells. In the present study, oxygen transport simulations were used to optimize the geometric design parameters for a similar system which is easier to fabricate. The system is composed of a microfluidic device stacked on top of a large, gas impermeable flow channel with a hole to allow gas exchange. The microfluidic device is fabricated using soft lithography in polydimethyl-siloxane, an oxygen permeable material. Our objective is twofold: (1) optimize the parameters of our system and (2) develop a method to assess the oxygen distribution in complex 3D microfluidic device geometries. 3D simulations of oxygen transport were performed to simulate oxygen distribution throughout the device. The simulations demonstrate that microfluidic device geometry plays a critical role in molecule exchange, for instance, changing the orientation of the short wide microfluidic channel results in a 97.17% increase in oxygen exchange. Since microfluidic devices have become a more prominent tool in biological studies, understanding the transport of oxygen and other biological molecules in microfluidic devices is critical for maintaining a physiologically relevant environment. We have also demonstrated a method to assess oxygen levels in geometrically complex microfluidic devices. PMID:27829071

  14. Functional Microcapsules via Thiol-Ene Photopolymerization in Droplet-Based Microfluidics.

    PubMed

    Amato, Douglas V; Lee, Hyomin; Werner, Jörg G; Weitz, David A; Patton, Derek L

    2017-02-01

    Thiol-ene chemistry was exploited in droplet-based microfluidics to fabricate advanced microcapsules with tunable encapsulation, degradation, and thermal properties. In addition, by utilizing the thiol-ene photopolymerization with tunable cross-link density, we demonstrate the importance of monomer conversion on the retention of omniphilic cargo in double emulsion templated microcapsules. Furthermore, we highlight the rapid cure kinetics afforded by thiol-ene chemistry in a continuous flow photopatterning device for hemispherical microparticle production.

  15. Measurement and validation of cell-based assays with microfluidics at the National Institute of Standards and Technology.

    PubMed

    Cooksey, Gregory A; Atencia, Javier; Forry, Samuel P

    2012-08-01

    The National Institute of Standards and Technology (NIST) is the National Metrology Institute for the USA. Our mission is to advance measurement science, standards and technology in ways that enhance economic security and improve quality of life in the USA. Due to the increased need for technologies that advance biological research and the many new and exciting innovations in microfluidics, our projects are aimed at engineering well-controlled microenvironments for quantitative measurements of cell behavior in microfluidic systems. Cell-based microfluidics at NIST is a highly multidisciplinary activity and is greatly influenced by NIST programs in biochemical sciences, materials science, engineering and information technology. Although there are many microfluidic-related activities ongoing at NIST, we will focus on projects related to cell-based measurements in this article.

  16. Highly Flexible Graphene Oxide Nanosuspension Liquid-Based Microfluidic Tactile Sensor.

    PubMed

    Kenry; Yeo, Joo Chuan; Yu, Jiahao; Shang, Menglin; Loh, Kian Ping; Lim, Chwee Teck

    2016-03-23

    A novel graphene oxide (GO) nanosuspension liquid-based microfluidic tactile sensor is developed. It comprises a UV ozone-bonded Ecoflex-polydimethylsiloxane microfluidic assembly filled with GO nanosuspension, which serves as the working fluid of the tactile sensor. This device is highly flexible and able to withstand numerous modes of deformation as well as distinguish various user-applied mechanical forces it is subjected to, including pressing, stretching, and bending. This tactile sensor is also highly deformable and wearable, and capable of recognizing and differentiating distinct hand muscle-induced motions, such as finger flexing and fist clenching. Moreover, subtle differences in the handgrip strength derived from the first clenching gesture can be identified based on the electrical response of our device. This work highlights the potential application of the GO nanosuspension liquid-based flexible microfluidic tactile sensing platform as a wearable diagnostic and prognostic device for real-time health monitoring. Also importantly, this work can further facilitate the exploration and potential realization of a functional liquid-state device technology with superior mechanical flexibility and conformability.

  17. Capillary-driven surface-enhanced Raman scattering (SERS)-based microfluidic chip for abrin detection

    NASA Astrophysics Data System (ADS)

    Yang, Hao; Deng, Min; Ga, Shan; Chen, Shouhui; Kang, Lin; Wang, Junhong; Xin, Wenwen; Zhang, Tao; You, Zherong; An, Yuan; Wang, Jinglin; Cui, Daxiang

    2014-03-01

    Herein, we firstly demonstrate the design and the proof-of-concept use of a capillary-driven surface-enhanced Raman scattering (SERS)-based microfluidic chip for abrin detection. The micropillar array substrate was etched and coated with a gold film by microelectromechanical systems (MEMS) process to integrate into a lateral flow test strip. The detection of abrin solutions of various concentrations was performed by the as-prepared microfluidic chip. It was shown that the correlation between the abrin concentration and SERS signal was found to be linear within the range of 0.1 ng/mL to 1 μg/mL with a limit of detection of 0.1 ng/mL. Our microfluidic chip design enhanced the operability of SERS-based immunodiagnostic techniques, significantly reducing the complication and cost of preparation as compared to previous SERS-based works. Meanwhile, this design proved the superiority to conventional lateral flow test strips in respect of both sensitivity and quantitation and showed great potential in the diagnosis and treatment for abrin poisoning as well as on-site screening of abrin-spiked materials.

  18. PDMS as a sacrificial substrate for SU-8-based biomedical and microfluidic applications

    NASA Astrophysics Data System (ADS)

    Patel, Jasbir N.; Kaminska, Bozena; Gray, Bonnie L.; Gates, Byron D.

    2008-09-01

    We describe a new fabrication process utilizing polydimethylesiloxane (PDMS) as a sacrificial substrate layer for fabricating free-standing SU-8-based biomedical and microfluidic devices. The PDMS-on-glass substrate permits SU-8 photo patterning and layer-to-layer bonding. We have developed a novel PDMS-based process which allows the SU-8 structures to be easily peeled off from the substrate after complete fabrication. As an example, a fully enclosed microfluidic chip has been successfully fabricated utilizing the presented new process. The enclosed microfluidic chip uses adhesive bonding technology and the SU-8 layers from 10 µm to 450 µm thick for fully enclosed microchannels. SU-8 layers as large as the glass substrate are successfully fabricated and peeled off from the PDMS layer as single continuous sheets. The fabrication results are supported by optical microscopy and profilometry. The peel-off force for the 120 µm thick SU-8-based chips is measured using a voice coil actuator (VCA). As an additional benefit the release step leaves the input and the output of the microchannels accessible to the outside world facilitating interconnecting to the external devices.

  19. Agarose-based microfluidic device for point-of-care concentration and detection of pathogen.

    PubMed

    Li, Yiwei; Yan, Xinghua; Feng, Xiaojun; Wang, Jie; Du, Wei; Wang, Yachao; Chen, Peng; Xiong, Liang; Liu, Bi-Feng

    2014-11-04

    Preconcentration of pathogens from patient samples represents a great challenge in point-of-care (POC) diagnostics. Here, a low-cost, rapid, and portable agarose-based microfluidic device was developed to concentrate biological fluid from micro- to picoliter volume. The microfluidic concentrator consisted of a glass slide simply covered by an agarose layer with a binary tree-shaped microchannel, in which pathogens could be concentrated at the end of the microchannel due to the capillary effect and the strong water permeability of the agarose gel. The fluorescent Escherichia coli strain OP50 was used to demonstrate the capacity of the agarose-based device. Results showed that 90% recovery efficiency could be achieved with a million-fold volume reduction from 400 μL to 400 pL. For concentration of 1 × 10(3) cells mL(-1) bacteria, approximately ten million-fold enrichment in cell density was realized with volume reduction from 100 μL to 1.6 pL. Urine and blood plasma samples were further tested to validate the developed method. In conjugation with fluorescence immunoassay, we successfully applied the method to the concentration and detection of infectious Staphylococcus aureus in clinics. The agarose-based microfluidic concentrator provided an efficient approach for POC detection of pathogens.

  20. Cyclic olefin homopolymer-based microfluidics for protein crystallization and in situ X-ray diffraction

    SciTech Connect

    Emamzadah, Soheila; Petty, Tom J.; De Almeida, Victor; Nishimura, Taisuke; Joly, Jacques; Ferrer, Jean-Luc; Halazonetis, Thanos D.

    2009-09-01

    A cyclic olefin homopolymer-based microfluidics system has been established for protein crystallization and in situ X-ray diffraction. Microfluidics is a promising technology for the rapid identification of protein crystallization conditions. However, most of the existing systems utilize silicone elastomers as the chip material which, despite its many benefits, is highly permeable to water vapour. This limits the time available for protein crystallization to less than a week. Here, the use of a cyclic olefin homopolymer-based microfluidics system for protein crystallization and in situ X-ray diffraction is described. Liquid handling in this system is performed in 2 mm thin transparent cards which contain 500 chambers, each with a volume of 320 nl. Microbatch, vapour-diffusion and free-interface diffusion protocols for protein crystallization were implemented and crystals were obtained of a number of proteins, including chicken lysozyme, bovine trypsin, a human p53 protein containing both the DNA-binding and oligomerization domains bound to DNA and a functionally important domain of Arabidopsis Morpheus’ molecule 1 (MOM1). The latter two polypeptides have not been crystallized previously. For X-ray diffraction analysis, either the cards were opened to allow mounting of the crystals on loops or the crystals were exposed to X-rays in situ. For lysozyme, an entire X-ray diffraction data set at 1.5 Å resolution was collected without removing the crystal from the card. Thus, cyclic olefin homopolymer-based microfluidics systems have the potential to further automate protein crystallization and structural genomics efforts.

  1. Integrated Microfluidic System Based on Electrowetting and its Application to Amino Acid Sensing Based on Electrochemiluminescence

    NASA Astrophysics Data System (ADS)

    Hosono, Hiroki; Satoh, Wataru; Suzuki, Hiroaki

    A microfluidic system to transport and mix solutions was fabricated and used for the detection of amino acids. A solution filled in the injection port was transported through a space between an elongated gold working electrode and a protruding structure of polydimethylsiloxane (PDMS). The transport was possible because the electrode surface was made hydrophilic by changing the potential of the gold working electrode. The same principle was used to mix two solutions. To demonstrate the system's applicability, optical biosensing based on electrochemiluminescence (ECL) was conducted on the chip. A necessary reagent solution (Ru(bpy)32+) and a sample solution (amino acid) were transported and mixed. ECL was observed on a platinum working electrode by applying a positive potential. Linear relationships were observed between the ECL intensity and the amino acid concentration.

  2. A Microfluidic DNA Sensor Based on Three-Dimensional (3D) Hierarchical MoS2/Carbon Nanotube Nanocomposites

    PubMed Central

    Yang, Dahou; Tayebi, Mahnoush; Huang, Yinxi; Yang, Hui Ying; Ai, Ye

    2016-01-01

    In this work, we present a novel microfluidic biosensor for sensitive fluorescence detection of DNA based on 3D architectural MoS2/multi-walled carbon nanotube (MWCNT) nanocomposites. The proposed platform exhibits a high sensitivity, selectivity, and stability with a visible manner and operation simplicity. The excellent fluorescence quenching stability of a MoS2/MWCNT aqueous solution coupled with microfluidics will greatly simplify experimental steps and reduce time for large-scale DNA detection. PMID:27854247

  3. Integrated Microfluidic Reactors.

    PubMed

    Lin, Wei-Yu; Wang, Yanju; Wang, Shutao; Tseng, Hsian-Rong

    2009-12-01

    Microfluidic reactors exhibit intrinsic advantages of reduced chemical consumption, safety, high surface-area-to-volume ratios, and improved control over mass and heat transfer superior to the macroscopic reaction setting. In contract to a continuous-flow microfluidic system composed of only a microchannel network, an integrated microfluidic system represents a scalable integration of a microchannel network with functional microfluidic modules, thus enabling the execution and automation of complicated chemical reactions in a single device. In this review, we summarize recent progresses on the development of integrated microfluidics-based chemical reactors for (i) parallel screening of in situ click chemistry libraries, (ii) multistep synthesis of radiolabeled imaging probes for positron emission tomography (PET), (iii) sequential preparation of individually addressable conducting polymer nanowire (CPNW), and (iv) solid-phase synthesis of DNA oligonucleotides. These proof-of-principle demonstrations validate the feasibility and set a solid foundation for exploring a broad application of the integrated microfluidic system.

  4. 3D printed microfluidic circuitry via multijet-based additive manufacturing†

    PubMed Central

    Sochol, R. D.; Sweet, E.; Glick, C. C.; Venkatesh, S.; Avetisyan, A.; Ekman, K. F.; Raulinaitis, A.; Tsai, A.; Wienkers, A.; Korner, K.; Hanson, K.; Long, A.; Hightower, B. J.; Slatton, G.; Burnett, D. C.; Massey, T. L.; Iwai, K.; Lee, L. P.; Pister, K. S. J.; Lin, L.

    2016-01-01

    The miniaturization of integrated fluidic processors affords extensive benefits for chemical and biological fields, yet traditional, monolithic methods of microfabrication present numerous obstacles for the scaling of fluidic operators. Recently, researchers have investigated the use of additive manufacturing or “three-dimensional (3D) printing” technologies – predominantly stereolithography – as a promising alternative for the construction of submillimeter-scale fluidic components. One challenge, however, is that current stereolithography methods lack the ability to simultaneously print sacrificial support materials, which limits the geometric versatility of such approaches. In this work, we investigate the use of multijet modelling (alternatively, polyjet printing) – a layer-by-layer, multi-material inkjetting process – for 3D printing geometrically complex, yet functionally advantageous fluidic components comprised of both static and dynamic physical elements. We examine a fundamental class of 3D printed microfluidic operators, including fluidic capacitors, fluidic diodes, and fluidic transistors. In addition, we evaluate the potential to advance on-chip automation of integrated fluidic systems via geometric modification of component parameters. Theoretical and experimental results for 3D fluidic capacitors demonstrated that transitioning from planar to non-planar diaphragm architectures improved component performance. Flow rectification experiments for 3D printed fluidic diodes revealed a diodicity of 80.6 ± 1.8. Geometry-based gain enhancement for 3D printed fluidic transistors yielded pressure gain of 3.01 ± 0.78. Consistent with additional additive manufacturing methodologies, the use of digitally-transferrable 3D models of fluidic components combined with commercially-available 3D printers could extend the fluidic routing capabilities presented here to researchers in fields beyond the core engineering community. PMID:26725379

  5. 3D printed microfluidic circuitry via multijet-based additive manufacturing.

    PubMed

    Sochol, R D; Sweet, E; Glick, C C; Venkatesh, S; Avetisyan, A; Ekman, K F; Raulinaitis, A; Tsai, A; Wienkers, A; Korner, K; Hanson, K; Long, A; Hightower, B J; Slatton, G; Burnett, D C; Massey, T L; Iwai, K; Lee, L P; Pister, K S J; Lin, L

    2016-02-21

    The miniaturization of integrated fluidic processors affords extensive benefits for chemical and biological fields, yet traditional, monolithic methods of microfabrication present numerous obstacles for the scaling of fluidic operators. Recently, researchers have investigated the use of additive manufacturing or "three-dimensional (3D) printing" technologies - predominantly stereolithography - as a promising alternative for the construction of submillimeter-scale fluidic components. One challenge, however, is that current stereolithography methods lack the ability to simultaneously print sacrificial support materials, which limits the geometric versatility of such approaches. In this work, we investigate the use of multijet modelling (alternatively, polyjet printing) - a layer-by-layer, multi-material inkjetting process - for 3D printing geometrically complex, yet functionally advantageous fluidic components comprised of both static and dynamic physical elements. We examine a fundamental class of 3D printed microfluidic operators, including fluidic capacitors, fluidic diodes, and fluidic transistors. In addition, we evaluate the potential to advance on-chip automation of integrated fluidic systems via geometric modification of component parameters. Theoretical and experimental results for 3D fluidic capacitors demonstrated that transitioning from planar to non-planar diaphragm architectures improved component performance. Flow rectification experiments for 3D printed fluidic diodes revealed a diodicity of 80.6 ± 1.8. Geometry-based gain enhancement for 3D printed fluidic transistors yielded pressure gain of 3.01 ± 0.78. Consistent with additional additive manufacturing methodologies, the use of digitally-transferrable 3D models of fluidic components combined with commercially-available 3D printers could extend the fluidic routing capabilities presented here to researchers in fields beyond the core engineering community.

  6. A competitive immunoassay system for microfluidic paper-based analytical detection of small size molecules.

    PubMed

    Busa, Lori Shayne Alamo; Mohammadi, Saeed; Maeki, Masatoshi; Ishida, Akihiko; Tani, Hirofumi; Tokeshi, Manabu

    2016-11-28

    The development of a competitive immunoassay system for colorimetric detection on microfluidic paper-based analytical devices (μPADs) is reported. The μPADs were fabricated via photolithography to define hydrophilic flow channels and consisted of three main elements: the control and test zones, where target detection was performed, the sample introduction zone, and the competitive capture zone located between the sample introduction zone and the test zone. The chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) was deposited at the control and test zones. μPAD surface modification was performed at the capture zone first via chitosan activation, then the BSA-conjugated target compound was immobilized. The sample solution consisting of the target compound, the peroxidase-conjugated antibody, and the hydrogen peroxide oxidizing agent was introduced into the device and competition occurred at the capture zone, allowing only the target-bound peroxidase-conjugated antibody to travel past the capture zone and into the test zone via capillary action. The developed competitive immunoassay system was successfully demonstrated on the μPAD detection of biotin as a model compound with a detection limit of 0.10 μg mL(-1). The applicability of the proposed immunoassay system for point-of-need testing was further demonstrated using aflatoxin B1, a highly toxic foodborne substance, with a detection limit of 1.31 ng mL(-1). The μPAD with the competitive immunoassay format showed promising results for practical applications in point-of-need testing involving small molecular weight targets in food and water safety and quality monitoring, environmental analysis, and clinical diagnostics.

  7. A parallel diffusion-based microfluidic device for bacterial chemotaxis analysis.

    PubMed

    Si, Guangwei; Yang, Wei; Bi, Shuangyu; Luo, Chunxiong; Ouyang, Qi

    2012-04-07

    We developed a multiple-channel microfluidic device for bacterial chemotaxis detection. Some characteristics such as easy operation, parallel sample adding design and fast result readout make this device convenient for most biology labs. The characteristic feature of the design is the agarose gel channels, which serve as a semi-permeable membrane. They can stop the fluid flow and prevent bacteria getting across, but permit the diffusion of small molecules. In the device fabrication process a novel thermal-based method was used to control the shape of agarose gel in the microfluidic channel. The chemical gradient is established by diffusion which can be precisely controlled and measured. Combined with an 8-channel pipette, different attractants, repellent chemicals or different bacteria were analyzed by a two step operation with a readout time of one hour. This device may be useful in the high throughput detection of chemotaxis related molecules and genes.

  8. Control of microparticles packing density in a microfluidic channel for bead based immunoassays applications

    NASA Astrophysics Data System (ADS)

    Caballero-Robledo, Gabriel; Guevara-Pantoja, Pablo

    2014-11-01

    Bead based immunoassays in microfluidic devices have shown to greatly outperform conventional methods. But if functional point-of-care devices are to be developed, precise and reproducible control over the granulate packings inside microchannels is needed. In this work we study the efficiency of a nanoparticles magnetic trap previously developed by B. Teste et al. [Lab Chip 11, 4207 (2011)] when we vary the compaction of micrometric iron beads packed against a restriction inside a microfluidic channel. The packing density of the beads is finely and reproducibly changed by applying a vibrational protocol originally developed for macroscopic, dry granular systems. We find, counterintuitively, that the most compact and stable packings are up to four times less efficient in trapping nano particles than the loosest packings. This work has been supported by Conacyt, Mexico, under Grant No. 180873.

  9. Volumetric measurement of human red blood cells by MOSFET-based microfluidic gate.

    PubMed

    Guo, Jinhong; Ai, Ye; Cheng, Yuanbing; Li, Chang Ming; Kang, Yuejun; Wang, Zhiming

    2015-08-01

    In this paper, we present a MOSFET-based (metal oxide semiconductor field-effect transistor) microfluidic gate to characterize the translocation of red blood cells (RBCs) through a gate. In the microfluidic system, the bias voltage modulated by the particles or biological cells is connected to the gate of MOSFET. The particles or cells can be detected by monitoring the MOSFET drain current instead of DC/AC-gating method across the electronic gate. Polystyrene particles with various standard sizes are utilized to calibrate the proposed device. Furthermore, RBCs from both adults and newborn blood sample are used to characterize the performance of the device in distinguishing the two types of RBCs. As compared to conventional DC/AC current modulation method, the proposed device demonstrates a higher sensitivity and is capable of being a promising platform for bioassay analysis.

  10. [A novel method based on Y-shaped cotton-polyester thread microfluidic channel].

    PubMed

    Wang, Lu; Shi, Yan-ru; Yan, Hong-tao

    2014-08-01

    A novel method based on Y-shaped microfluidic channel was firstly proposed in this study. The microfluidic channel was made of two cotton-polyester threads based on the capillary effect of cotton-polyester threads for the determination solutions. A special device was developed to fix the Y-shaped microfluidic channel by ourselves, through which the length and the tilt angle of the channel can be adjusted as requested. The spectrophotometry was compared with Scan-Adobe Photoshop software processing method. The former had a lower detection limit while the latter showed advantages in both convenience and fast operations and lower amount of samples. The proposed method was applied to the determination of nitrite. The linear ranges and detection limits are 1.0-70 micromol x L(-1), 0.66 micromol x L(-1) (spectrophotometry) and 50-450 micromol x L(-1), 45.10 micromol x L(-1) (Scan-Adobe Photoshop software processing method) respectively. This method has been successfully used to the determination of nitrite in soil samples and moat water with recoveries between 96.7% and 104%. It was proved that the proposed method was a low-cost, rapid and convenient analytical method with extensive application prospect.

  11. Cyclic olefin homopolymer-based microfluidics for protein crystallization and in situ X-ray diffraction.

    PubMed

    Emamzadah, Soheila; Petty, Tom J; De Almeida, Victor; Nishimura, Taisuke; Joly, Jacques; Ferrer, Jean Luc; Halazonetis, Thanos D

    2009-09-01

    Microfluidics is a promising technology for the rapid identification of protein crystallization conditions. However, most of the existing systems utilize silicone elastomers as the chip material which, despite its many benefits, is highly permeable to water vapour. This limits the time available for protein crystallization to less than a week. Here, the use of a cyclic olefin homopolymer-based microfluidics system for protein crystallization and in situ X-ray diffraction is described. Liquid handling in this system is performed in 2 mm thin transparent cards which contain 500 chambers, each with a volume of 320 nl. Microbatch, vapour-diffusion and free-interface diffusion protocols for protein crystallization were implemented and crystals were obtained of a number of proteins, including chicken lysozyme, bovine trypsin, a human p53 protein containing both the DNA-binding and oligomerization domains bound to DNA and a functionally important domain of Arabidopsis Morpheus' molecule 1 (MOM1). The latter two polypeptides have not been crystallized previously. For X-ray diffraction analysis, either the cards were opened to allow mounting of the crystals on loops or the crystals were exposed to X-rays in situ. For lysozyme, an entire X-ray diffraction data set at 1.5 A resolution was collected without removing the crystal from the card. Thus, cyclic olefin homopolymer-based microfluidics systems have the potential to further automate protein crystallization and structural genomics efforts.

  12. Cell migration microfluidics for electrotaxis-based heterogeneity study of lung cancer cells.

    PubMed

    Li, Yaping; Xu, Tao; Zou, Heng; Chen, Xiaomei; Sun, Dong; Yang, Mengsu

    2017-03-15

    Tumor metastasis involves the migration of cells from primary site to a distant location. Recently, it was established that cancer cells from the same tumor were heterogeneous in migratory ability. Numerous studies have demonstrated that cancer cells undergo reorientation and migration directionally under physiological electric field (EF), which has potential implications in metastasis. Microfluidic devices with channel structures of defined dimensions provide controllable microenvironments to enable real-time observation of cell migration. In this study, we developed two polydimethylsiloxane (PDMS)-based microfluidic devices for long-term electrotaxis study. In the first chip, three different intensities of EFs were generated in a single channel to study cell electrotactic behavior with high efficiency. We observed that the lung adenocarcinoma H1975 cells underwent cathodal migration with changing cellular orientation. To address the issue of cell electrotactic heterogeneity, we also developed a cell isolation device integrating cell immobilization structure, stable EF generator and cell retrieval module in one microfluidic chip to sort out different cell subpopulations based on electrotactic ability. High electrotactic and low electrotactic cells were harvested separately for colony formation assay and transcriptional analysis of migration-related genes. The results showed that H1975 cell motility was related to EGFR expression in the absence of EF stimulation, while in the presence of EF it was associated with PTEN expression. Up-regulation of RhoA was observed in cells with high motility, regardless of EF. The easy cell manipulation and precise field control of the microfluidic devices may enable further study of tumor heterogeneity in complex electrotactic environments.

  13. Finger-Powered Electro-Digital-Microfluidics.

    PubMed

    Peng, Cheng; Ju, Y Sungtaek

    2017-01-01

    Portable microfluidic devices are promising for point-of-care (POC) diagnosis and bio- and environmental surveillance in resource-constrained or non-laboratory environments. Lateral-flow devices, some built off paper or strings, have been widely developed but the fixed layouts of their underlying wicking/microchannel structures limit their flexibility and present challenges in implementing multistep reactions. Digital microfluidics can circumvent these difficulties by addressing discrete droplets individually. Existing approaches to digital microfluidics, however, often require bulky power supplies/batteries and high voltage circuits. We present a scheme to drive digital microfluidic devices by converting mechanical energy of human fingers to electrical energy using an array of piezoelectric elements. We describe the integration our scheme into two promising digital microfluidics platforms: one based on the electro-wetting-on-dielectric (EWOD) phenomenon and the other on the electrophoretic control of droplet (EPD). Basic operations of droplet manipulations, such as droplet transport, merging and splitting, are demonstrated using the finger-powered digital-microfluidics.

  14. Plug-n-play microfluidic systems from flexible assembly of glass-based flow-control modules.

    PubMed

    Meng, Zhi-Jun; Wang, Wei; Liang, Xuan; Zheng, Wei-Chao; Deng, Nan-Nan; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2015-04-21

    In this study, we report on a simple and versatile plug-n-play microfluidic system that is fabricated from flexible assembly of glass-based flow-control modules for flexibly manipulating flows for versatile emulsion generation. The microfluidic system consists of three basic functional units: a flow-control module, a positioning groove, and a connection fastener. The flow-control module that is based on simple assembly of low-cost glass slides, coverslips, and glass capillaries provides excellent chemical resistance and optical properties, and easy wettability modification for flow manipulation. The flexible combination of the flow-control modules with 3D-printed positioning grooves and connection fasteners enables creation of versatile microfluidic systems for generating various higher-order multiple emulsions. The simple and reversible connection of the flow-control modules also allows easy disassembly of the microfluidic systems for further scale-up and functionalization. We demonstrate the scalability and controllability of flow manipulation by creating microfluidic systems from flexible assembly of flow-control modules for controllable generation of multiple emulsions from double emulsions to quadruple emulsions. Meanwhile, the flexible flow manipulation in the flow-control module provides advanced functions for improved control of the drop size, and for controllable generation of drops containing distinct components within multiple emulsions to extend the emulsion structure. Such modular microfluidic systems provide flexibility and versatility to flexibly manipulate micro-flows for enhanced and extended applications.

  15. Protein Microarrays with Novel Microfluidic Methods: Current Advances.

    PubMed

    Dixit, Chandra K; Aguirre, Gerson R

    2014-07-01

    Microfluidic-based micromosaic technology has allowed the pattering of recognition elements in restricted micrometer scale areas with high precision. This controlled patterning enabled the development of highly multiplexed arrays multiple analyte detection. This arraying technology was first introduced in the beginning of 2001 and holds tremendous potential to revolutionize microarray development and analyte detection. Later, several microfluidic methods were developed for microarray application. In this review we discuss these novel methods and approaches which leverage the property of microfluidic technologies to significantly improve various physical aspects of microarray technology, such as enhanced imprinting homogeneity, stability of the immobilized biomolecules, decreasing assay times, and reduction of the costs and of the bulky instrumentation.

  16. Highly efficient bienzyme functionalized nanocomposite-based microfluidics biosensor platform for biomedical application.

    PubMed

    Ali, Md Azahar; Srivastava, Saurabh; Solanki, Pratima R; Reddy, Venu; Agrawal, Ved V; Kim, CheolGi; John, Renu; Malhotra, Bansi D

    2013-09-27

    This report describes the fabrication of a novel microfluidics nanobiochip based on a composite comprising of nickel oxide nanoparticles (nNiO) and multiwalled carbon nanotubes (MWCNTs), as well as the chip's use in a biomedical application. This nanocomposite was integrated with polydimethylsiloxane (PDMS) microchannels, which were constructed using the photolithographic technique. A structural and morphological characterization of the fabricated microfluidics chip, which was functionalized with a bienzyme containing cholesterol oxidase (ChOx) and cholesterol esterase (ChEt), was accomplished using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The XPS studies revealed that 9.3% of the carboxyl (COOH) groups present in the nNiO-MWCNT composite are used to form amide bonds with the NH2 groups of the bienzyme. The response studies on this nanobiochip reveal good reproducibility and selectivity, and a high sensitivity of 2.2 mA/mM/cm2. This integrated microfluidics biochip provides a promising low-cost platform for the rapid detection of biomolecules using minute samples.

  17. Microfluidics-based point-of-care test for serodiagnosis of Lyme Disease

    PubMed Central

    Nayak, Samiksha; Sridhara, Archana; Melo, Rita; Richer, Luciana; Chee, Natalie H.; Kim, Jiyoon; Linder, Vincent; Steinmiller, David; Sia, Samuel K.; Gomes-Solecki, Maria

    2016-01-01

    Currently, diagnostic testing for Lyme disease is done by determination of the serologic responses to Borrelia burgdorferi antigens, with the exception of the early localized phase of disease where diagnosis must be done clinically. Here, we describe the use of microfluidics technology to develop a multiplexed rapid lab-on-a-chip point of care (POC) assay for the serologic diagnosis of human Lyme disease. Following ELISA screening of 12 candidate antigens, we tested 8 on a microfluidic diagnostic system, called mChip-Ld, using a set of 60 serological samples. The mChip-Ld test, which can be performed in 15 minutes at the point of care, showed promising performance for detection of antibodies to B. burgdorferi using the PPO triplex test (rP100 + PepVF + rOspC-K, AUC of 0.844) compared to a gold-standard reference of culture confirmed clinical samples. The performance is comparable to the commonly used C6 peptide by lab-based ELISA. In addition, the mChip-Ld test showed promising performance for early-stage diagnosis of the disease using the antigen OspC-K (sensitivity and specificity of 84% and 92%, respectively; AUC of 0.877). Overall, this study underscores the potential of using microfluidics to aid the diagnosis of Lyme disease at the point of care. PMID:27725740

  18. Purification of microalgae from bacterial contamination using a disposable inertia-based microfluidic device

    NASA Astrophysics Data System (ADS)

    Godino, Neus; Jorde, Felix; Lawlor, Daryl; Jaeger, Magnus; Duschl, Claus

    2015-08-01

    Microalgae are a promising source of bioactive ingredients for the food, pharmaceutical and cosmetic industries. Every microalgae research group or production facility is facing one major problem regarding the potential contamination of the algal cell with bacteria. Prior to the storage of the microalgae in strain collections or to cultivation in bioreactors, it is necessary to carry out laborious purification procedures to separate the microalgae from the undesired bacterial cells. In this work, we present a disposable microfluidic cartridge for the high-throughput purification of microalgae samples based on inertial microfluidics. Some of the most relevant microalgae strains have a larger size than the relatively small, few micron bacterial cells, so making them distinguishable by size. The inertial microfluidic cartridge was fabricated with inexpensive materials, like pressure sensitive adhesive (PSA) and thin plastic layers, which were patterned using a simple cutting plotter. In spite of fabrication restrictions and the intrinsic difficulties of biological samples, the separation of microalgae from bacteria reached values in excess of 99%, previously only achieved using conventional high-end and high cost lithography methods. Moreover, due to the simple and high-throughput characteristic of the separation, it is possible to concatenate serial purification to exponentially decrease the absolute amount of bacteria in the final purified sample.

  19. A fluorescence-based centrifugal microfluidic system for parallel detection of multiple allergens

    NASA Astrophysics Data System (ADS)

    Chen, Q. L.; Ho, H. P.; Cheung, K. L.; Kong, S. K.; Suen, Y. K.; Kwan, Y. W.; Li, W. J.; Wong, C. K.

    2010-02-01

    This paper reports a robust polymer based centrifugal microfluidic analysis system that can provide parallel detection of multiple allergens in vitro. Many commercial food products (milk, bean, pollen, etc.) may introduce allergy to people. A low-cost device for rapid detection of allergens is highly desirable. With this as the objective, we have studied the feasibility of using a rotating disk device incorporating centrifugal microfluidics for performing actuationfree and multi-analyte detection of different allergen species with minimum sample usage and fast response time. Degranulation in basophils or mast cells is an indicator to demonstrate allergic reaction. In this connection, we used acridine orange (AO) to demonstrate degranulation in KU812 human basophils. It was found that the AO was released from granules when cells were stimulated by ionomycin, thus signifying the release of histamine which accounts for allergy symptoms [1-2]. Within this rotating optical platform, major microfluidic components including sample reservoirs, reaction chambers, microchannel and flow-control compartments are integrated into a single bio-compatible polydimethylsiloxane (PDMS) substrate. The flow sequence and reaction time can be controlled precisely. Sequentially through varying the spinning speed, the disk may perform a variety of steps on sample loading, reaction and detection. Our work demonstrates the feasibility of using centrifugation as a possible immunoassay system in the future.

  20. Standard and high-throughput microfluidic disposables based on laminar fluid diffusion interfaces

    NASA Astrophysics Data System (ADS)

    Weigl, Bernhard H.; Morris, Chris; Kesler, Natasa; Battrell, Fred; Bardell, Ron L.

    2002-06-01

    Laminar Fluid Diffusion Interfaces are generated when tow or more streams flow in parallel in a microfluidic structure. This technology can be used for diffusion-based separation and detection applications, for example: DNA desalting, the extraction of small proteins from whole-blood samples, and the detection of various constituents in while blood. Additional applications are the establishment of stable concentration gradients, and the exposure of chemical constituents or biological particles to these concentration gradients, enabling the uniform and controlled exposure of cells to lysing agents, allowing the differentiation of cells by their sensitivity to specific agents in an on-chip cytometer coupled directly to the lysing structure. We have developed integrated systems using machine-controlled disposable cartridges and passive self-contained disposable cards including particle separators, flow cytometers, valves, detection channels, mixers, and diluters that are used in a hematology analyzer, stand-alone blood plasma separators, and a variety of chemical and biological assays. Microfluidic arrays compatible with common well-plate formats have been designed for high-throughout toxicology screening applications. All these devices were manufactured using Micronics' unique rapid-prototyping process yielding low-cost plastic disposable microfluidic chips.

  1. Programmable and automated bead-based microfluidics for versatile DNA microarrays under isothermal conditions.

    PubMed

    Penchovsky, Robert

    2013-06-21

    Advances in modern genomic research depend heavily on applications of various devices for automated high- or ultra-throughput arrays. Micro- and nanofluidics offer possibilities for miniaturization and integration of many different arrays onto a single device. Therefore, such devices are becoming a platform of choice for developing analytical instruments for modern biotechnology. This paper presents an implementation of a bead-based microfluidic platform for fully automated and programmable DNA microarrays. The devices are designed to work under isothermal conditions as DNA immobilization and hybridization transfer are performed under steady temperature using reversible pH alterations of reaction solutions. This offers the possibility for integration of more selection modules onto a single chip compared to maintaining a temperature gradient. This novel technology allows integration of many modules on a single reusable chip reducing the application cost. The method takes advantage of demonstrated high-speed DNA hybridization kinetics and denaturation on beads under flow conditions, high-fidelity of DNA hybridization, and small sample volumes are needed. The microfluidic devices are applied for a single nucleotide polymorphism analysis and DNA sequencing by synthesis without the need for fluorescent removal step. Apart from that, the microfluidic platform presented is applicable to many areas of modern biotechnology, including biosensor devices, DNA hybridization microarrays, molecular computation, on-chip nucleic acid selection, high-throughput screening of chemical libraries for drug discovery.

  2. Microfluidic system for dielectrophoretic separation based on a trapezoidal electrode array.

    PubMed

    Choi, Sungyoung; Park, Je-Kyun

    2005-10-01

    This paper presents a novel microfluidic device for dielectrophoretic separation based on a trapezoidal electrode array (TEA). In this method, particles with different dielectric properties are separated by the device composed of the TEA for the dielectrophoretic deflection of particles under negative dielectrophoresis (DEP) and poly(dimethylsiloxane)(PDMS) microfluidic channel with a sinuous and expanded region. Polystyrene microparticles are exposed to an electric field generated from the TEA in the microfluidic channel and are dielectrophoretically focused to make all of them line up to one sidewall. When these particles arrive at the region of another TEA for dielectrophoretic separation, they are separated having different positions along the perpendicular direction to the fluid flow due to their different dielectrophoretic velocities. To evaluate the separation process and performance, both the effect of the flow rate on dielectrophoretic focusing and the influence of the number of trapezoidal electrodes on dielectrophoretic separation are investigated. Now that this method utilizes the TEA as a source of negative DEP, non-specific particle adhering to the electrode surface can be prevented; conventional separation approaches depending on the positive DEP force suffer from this problem. In addition, since various particle types are continuously separated, this method can be easily applicable to the separation and analysis of various dielectric particles with high particle recovery and selectivity.

  3. Detection of enzyme inhibitors in crude natural extracts using droplet-based microfluidics coupled to HPLC.

    PubMed

    Ochoa, Abraham; Álvarez-Bohórquez, Enrique; Castillero, Eduardo; Olguin, Luis F

    2017-04-04

    Natural product screening for new bioactive compounds can greatly benefit from low reagents consumption and high throughput capacity of droplet-based microfluidic systems. However, the creation of large droplet libraries in which each droplet carries a different compound is a challenging task. A possible solution is to use an HPLC coupled to a droplet generating microfluidic device to sequentially encapsulate the eluting compounds. In this work we demonstrate the feasibility of carrying out enzyme inhibiting assays inside nano-liter droplets with the different components of a natural crude extract after being separated by a coupled HPLC column. In the droplet formation zone, the eluted components are mixed with an enzyme and a fluorogenic substrate that permits to follow the enzymatic reaction in the presence of each chromatographic peak and identify those inhibiting the enzyme activity. Using a fractal shape channel design and automated image analysis we were able to identify inhibitors of Clostridium perfringens neuraminidase present in a root extract of the Pelargonium sidoides plant. This work demonstrates the feasibility of bioprofiling a natural crude extract after being separated in HPLC using microfluidic droplets on-line and represents an advance in the miniaturization of natural products screening.

  4. Highly Efficient Bienzyme Functionalized Nanocomposite-Based Microfluidics Biosensor Platform for Biomedical Application

    PubMed Central

    Ali, Md. Azahar; Srivastava, Saurabh; Solanki, Pratima R.; Reddy, Venu; Agrawal, Ved V.; Kim, CheolGi; John, Renu; Malhotra, Bansi D.

    2013-01-01

    This report describes the fabrication of a novel microfluidics nanobiochip based on a composite comprising of nickel oxide nanoparticles (nNiO) and multiwalled carbon nanotubes (MWCNTs), as well as the chip's use in a biomedical application. This nanocomposite was integrated with polydimethylsiloxane (PDMS) microchannels, which were constructed using the photolithographic technique. A structural and morphological characterization of the fabricated microfluidics chip, which was functionalized with a bienzyme containing cholesterol oxidase (ChOx) and cholesterol esterase (ChEt), was accomplished using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The XPS studies revealed that 9.3% of the carboxyl (COOH) groups present in the nNiO-MWCNT composite are used to form amide bonds with the NH2 groups of the bienzyme. The response studies on this nanobiochip reveal good reproducibility and selectivity, and a high sensitivity of 2.2 mA/mM/cm2. This integrated microfluidics biochip provides a promising low-cost platform for the rapid detection of biomolecules using minute samples. PMID:24071971

  5. A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing.

    PubMed

    Habhab, Mohammed-Baker; Ismail, Tania; Lo, Joe Fujiou

    2016-11-23

    Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications.

  6. A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing

    PubMed Central

    Habhab, Mohammed-Baker; Ismail, Tania; Lo, Joe Fujiou

    2016-01-01

    Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications. PMID:27886051

  7. Recombinant Protein-Stabilized Monodisperse Microbubbles with Tunable Size Using a Valve-Based Microfluidic Device

    PubMed Central

    2015-01-01

    Microbubbles are used as contrast enhancing agents in ultrasound sonography and more recently have shown great potential as theranostic agents that enable both diagnostics and therapy. Conventional production methods lead to highly polydisperse microbubbles, which compromise the effectiveness of ultrasound imaging and therapy. Stabilizing microbubbles with surfactant molecules that can impart functionality and properties that are desirable for specific applications would enhance the utility of microbubbles. Here we generate monodisperse microbubbles with a large potential for functionalization by combining a microfluidic method and recombinant protein technology. Our microfluidic device uses an air-actuated membrane valve that enables production of monodisperse microbubbles with narrow size distribution. The size of microbubbles can be precisely tuned by dynamically changing the dimension of the channel using the valve. The microbubbles are stabilized by an amphiphilic protein, oleosin, which provides versatility in controlling the functionalization of microbubbles through recombinant biotechnology. We show that it is critical to control the composition of the stabilizing agents to enable formation of highly stable and monodisperse microbubbles that are echogenic under ultrasound insonation. Our protein-shelled microbubbles based on the combination of microfluidic generation and recombinant protein technology provide a promising platform for ultrasound-related applications. PMID:25265041

  8. Nucleic Acid-based Detection of Bacterial Pathogens Using Integrated Microfluidic Platform Systems

    PubMed Central

    Lui, Clarissa; Cady, Nathaniel C.; Batt, Carl A.

    2009-01-01

    The advent of nucleic acid-based pathogen detection methods offers increased sensitivity and specificity over traditional microbiological techniques, driving the development of portable, integrated biosensors. The miniaturization and automation of integrated detection systems presents a significant advantage for rapid, portable field-based testing. In this review, we highlight current developments and directions in nucleic acid-based micro total analysis systems for the detection of bacterial pathogens. Recent progress in the miniaturization of microfluidic processing steps for cell capture, DNA extraction and purification, polymerase chain reaction, and product detection are detailed. Discussions include strategies and challenges for implementation of an integrated portable platform. PMID:22412335

  9. A collection of edge-based elements

    NASA Technical Reports Server (NTRS)

    Kempel, Leo C.; Volakis, John L.

    1992-01-01

    Edge-based elements have proved useful in solving electromagnetic problems since they are nondivergent. Previous authors have presented several two and three dimensional elements. Herein, we present four types of elements which are suitable for modeling several types of three dimensional geometries. Distorted brick and triangular prism elements are given in cartesian coordinates as well as the specialized cylindrical shell and pie-shaped prism elements which are suitable for problems best described in polar cylindrical coordinates.

  10. Microfluidic waves

    PubMed Central

    Utz, Marcel; Begley, Matthew R.; Haj-Hariri, Hossein

    2012-01-01

    The propagation of pressure waves in fluidic channels with elastic covers is discussed in view of applications to flow control in microfluidic devices. A theory is presented which describes pressure waves in the fluid that are coupled to bending waves in the elastic cover. At low frequencies, the lateral bending of the cover dominates over longitudinal bending, leading to propagating, non-dispersive longitudinal pressure waves in the channel. The theory addresses effects due to both the finite viscosity and compressibility of the fluid. The coupled waves propagate without dispersion, as long as the wave length is larger than the channel width. It is shown that in channels of typical microfluidic dimensions, wave velocities in the range of a few 10 m s−1 result if the channels are covered by films of a compliant material such as PDMS. The application of this principle to design microfluidic band pass filters based on standing waves is discussed. Characteristic frequencies in the range of a few kHz are readily achieved with quality factors above 30. PMID:21966667

  11. Fabrication of digital microfluidic devices on flexible paper-based and rigid substrates via screen printing

    NASA Astrophysics Data System (ADS)

    Yafia, Mohamed; Shukla, Saurabh; Najjaran, Homayoun

    2015-05-01

    In this work, a new fabrication method is presented for digital microfluidic (DMF) devices in which the electrodes are generated using the screen printing technique. This method is applicable to both rigid and flexible substrates. The proposed screen printing approach, as a batch printing technique, is advantageous to the widely reported DMF fabrication methods in terms of fabrication time, cost and capability of mass production. Screen printing provides an effective means for printing different types of conductive materials on a variety of substrates. Specifically, screen printing of conductive silver and carbon based inks is performed on paper, glass and wax paper. As a result, the fabricated DMF devices are characterized by being flexible, disposable and incinerable. Hence, the main advantage of screen printing carbon based inks on paper substrates is more pronounced for point-of-care applications that require a large number of low cost DMF chips, and laboratory setups that lack sophisticated microfabrication facilities. The resolution of the printed DMF electrodes generated by this technique is examined for proof of concept using manual screen printing, but higher resolution screens and automated machines are available off-the-shelf, if needed. Another contribution of this research is the improved actuation techniques that facilitate droplet transport in electrode configurations with relatively large electrode spacing to alleviate the disadvantage of lower resolution screens. Thus, we were able to reduce the cost of fabrication significantly without compromising the DMF performance. The paper-based devices have already shown to be effective in continuous microfluidics domain, so the investigation of their applicability in DMF systems is worthwhile. With this in mind, successful integration of a paper-based microchannel with paper-based digital microfluidic chip is demonstrated in this work.

  12. Streamline based design guideline for deterministic microfluidic hydrodynamic single cell traps

    PubMed Central

    Shenoy, Aditi; Smith, Richard

    2015-01-01

    A prerequisite for single cell study is the capture and isolation of individual cells. In microfluidic devices, cell capture is often achieved by means of trapping. While many microfluidic trapping techniques exist, hydrodynamic methods are particularly attractive due to their simplicity and scalability. However, current design guidelines for single cell hydrodynamic traps predominantly rely on flow resistance manipulation or qualitative streamline analysis without considering the target particle size. This lack of quantitative design criteria from first principles often leads to non-optimal probabilistic trapping. In this work, we describe an analytical design guideline for deterministic single cell hydrodynamic trapping through the optimization of streamline distributions under laminar flow with cell size as a key parameter. Using this guideline, we demonstrate an example design which can achieve 100% capture efficiency for a given particle size. Finite element modelling was used to determine the design parameters necessary for optimal trapping. The simulation results were subsequently confirmed with on-chip microbead and white blood cell trapping experiments. PMID:25825618

  13. Characterization and optimization of low cost microfluidic thread based electroanalytical device for micro flow injection analysis.

    PubMed

    Agustini, Deonir; Bergamini, Márcio F; Marcolino-Junior, Luiz Humberto

    2017-01-25

    The micro flow injection analysis (μFIA) is a powerful technique that uses the principles of traditional flow analysis in a microfluidic device and brings a number of improvements related to the consumption of reagents and samples, speed of analysis and portability. However, the complexity and cost of manufacturing processes, difficulty in integrating micropumps and the limited performance of systems employing passive pumps are challenges that must be overcome. Here, we present the characterization and optimization of a low cost device based on cotton threads as microfluidic channel to perform μFIA based on passive pumps with good analytical performance in a simple, easy and inexpensive way. The transport of solutions is made through cotton threads by capillary force facilitated by gravity. After studying and optimizing several features related to the device, were obtained a flow rate of 2.2 ± 0.1 μL s(-1), an analytical frequency of 208 injections per hour, a sample injection volume of 2.0 μL and a waste volume of approximately 40 μL per analysis. For chronoamperometric determination of naproxen, a detection limit of 0.29 μmol L(-1) was reached, with a relative standard deviation (RSD) of 1.69% between injections and a RSD of 3.79% with five different devices. Thus, based on the performance presented by proposed microfluidic device, it is possible to overcome some limitations of the μFIA systems based on passive pumps and allow expansion in the use of this technique.

  14. Biologically Inspired Electronic, Photovoltaic and Microfluidic Devices Based on Aqueous Soft Matter

    NASA Astrophysics Data System (ADS)

    Koo, Hyung Jun

    Hydrogels are a water-based soft material where three dimensional networks of hydrophilic polymer retain large amounts of water. We developed hydrogel based devices with new functionalities inspired by materials, structures and processes in nature. The advantages, such as softness, biocompatibility and high ionic conductivity, could enable hydrogels to be novel materials for biomimetic devices operated by ionic current. Moreover, microfluidic patterns are easily embedded in moldable hydrogels and allow for unique convective/diffusive transport mechanism in porous gel to be used for uniform delivery of reagent solution. We first developed and characterized a device with unidirectional ionic current flow across a SiO2/Gel junction, which showed highly efficient rectification of the ionic current by non-linear conductivity of SiO2 films. Addition of polyelectrolytes and salt to the gel layer significantly improved the performance of the new diode device because of the enhanced gel conductance. A soft matter based diode composed of hydrogel and liquid metal (eutectic gallium indium, EGaIn) was also presented. The ability to control the thickness, and thus resistivity, of an insulating oxide skin on the metal enables the current rectification. The effect of ionic conductivity and pH on the formation of the insulating oxide was investigated in a simple model system with liquid metal/electrolyte solution or hydrogel/Pt interfaces. Finally, we present a diode composed entirely of soft materials by replacing the platinum electrode with a second liquid metal electrode. A new type of hydrogel-based photovoltaic systems (HGPVs) was constructed. Two photosensitive ionized molecules embedded in aqueous gel served as photoactive species. The HGPVs showed performance comparable with or higher than those of some other biomimetic or ionic photovoltaic systems reported recently. We suggest a provisional mechanism of the device operation, based on a synergetic effect of the two dye

  15. Microfluidic neurotransmiter-based neural interfaces for retinal prosthesis.

    PubMed

    Iezzi, Raymond; Finlayson, Paul; Xu, Yong; Katragadda, Rakesh

    2009-01-01

    Natural inter-neuronal communication is mediated primarily via neurotransmitter-gated ion channels. While most of the methods for neural interfacing have been based upon electrical stimulation, neurotransmitter-based approaches for the spatially and temporally controlled delivery of neurotransmitters are relatively new. Methods of neurotransmitter stimulation retinal prosthesis may provide new ways to control neural excitation. Experimental results for retinal ganglion cell stimulation demonstrate the feasibility of a neurotransmitter-based retinal prosthesis.

  16. TECHNICAL NOTE: Portable audio electronics for impedance-based measurements in microfluidics

    NASA Astrophysics Data System (ADS)

    Wood, Paul; Sinton, David

    2010-08-01

    We demonstrate the use of audio electronics-based signals to perform on-chip electrochemical measurements. Cell phones and portable music players are examples of consumer electronics that are easily operated and are ubiquitous worldwide. Audio output (play) and input (record) signals are voltage based and contain frequency and amplitude information. A cell phone, laptop soundcard and two compact audio players are compared with respect to frequency response; the laptop soundcard provides the most uniform frequency response, while the cell phone performance is found to be insufficient. The audio signals in the common portable music players and laptop soundcard operate in the range of 20 Hz to 20 kHz and are found to be applicable, as voltage input and output signals, to impedance-based electrochemical measurements in microfluidic systems. Validated impedance-based measurements of concentration (0.1-50 mM), flow rate (2-120 µL min-1) and particle detection (32 µm diameter) are demonstrated. The prevailing, lossless, wave audio file format is found to be suitable for data transmission to and from external sources, such as a centralized lab, and the cost of all hardware (in addition to audio devices) is ~10 USD. The utility demonstrated here, in combination with the ubiquitous nature of portable audio electronics, presents new opportunities for impedance-based measurements in portable microfluidic systems.

  17. Novel concept of washing for microfluidic paper-based analytical devices based on capillary force of paper substrates.

    PubMed

    Mohammadi, Saeed; Busa, Lori Shayne Alamo; Maeki, Masatoshi; Mohamadi, Reza M; Ishida, Akihiko; Tani, Hirofumi; Tokeshi, Manabu

    2016-11-01

    A novel washing technique for microfluidic paper-based analytical devices (μPADs) that is based on the spontaneous capillary action of paper and eliminates unbound antigen and antibody in a sandwich immunoassay is reported. Liquids can flow through a porous medium (such as paper) in the absence of external pressure as a result of capillary action. Uniform results were achieved when washing a paper substrate in a PDMS holder which was integrated with a cartridge absorber acting as a porous medium. Our study demonstrated that applying this washing technique would allow μPADs to become the least expensive microfluidic device platform with high reproducibility and sensitivity. In a model μPAD assay that utilized this novel washing technique, C-reactive protein (CRP) was detected with a limit of detection (LOD) of 5 μg mL(-1). Graphical Abstract A novel washing technique for microfluidic paper-based analytical devices (μPADs) that is based on the spontaneous capillary action of paper and eliminates unbound antigen and antibody in a sandwich immunoassay is reported.

  18. Microfluidic platform for neurotransmitter sensing based on cyclic voltammetry and dielectrophoresis for in vitro experiments.

    PubMed

    Mathault, Jessy; Zamprogno, Pauline; Greener, Jesse; Miled, Amine

    2015-08-01

    This paper presents a new microfluidic platform that can simultaneously measure and locally modulate neurotransmitter concentration in a neuron network. This work focuses on the development of a first prototype including a potentiostat and electrode functionalization to detect several neurotransmitter's simultaneously. We tested dopamine as proof of concept to validate functionality. The system is based on 320 bidirectional electrode array for dielectrophoretic manipulation and cyclic voltammetry. Each electrode is connected to a mechanical multiplexer in order to reduce noise interference and fully isolate the electrode. The multiplexing rate is 476 kHz and each electrode can drive a signal with an amplitude of 60 V pp for dielectrophoretic manipulation.

  19. A paper based microfluidic device for easy detection of uric acid using positively charged gold nanoparticles.

    PubMed

    Kumar, Anand; Hens, Abhiram; Arun, Ravi Kumar; Chatterjee, Monosree; Mahato, Kuldeep; Layek, Keya; Chanda, Nripen

    2015-03-21

    A paper based microfluidic device is fabricated that can rapidly detect very low concentrations of uric acid (UA) using 3,5,3',5'-tetramethyl benzidine (TMB), H2O2 and positively charged gold nanoparticles ((+)AuNPs). In the presence of (+)AuNPs, H2O2 reacts with TMB to produce a bluish-green colour which becomes colourless on reaction with UA. This colorimetric method can detect as low as 8.1 ppm of UA within <20 minutes on white filter paper. This technique provides an alternative way for UA detection.

  20. Electroporation based on hydrodynamic focusing of microfluidics with low dc voltage.

    PubMed

    Zhu, Tao; Luo, Chunxiong; Huang, Jianyong; Xiong, Chunyang; Ouyang, Qi; Fang, Jing

    2010-02-01

    Microfluidics-based cell electroporation has many advantages in delivering small molecules into cells. In this study, hydrodynamic focusing of fluids with different conductivities has been used for high through-put cell electroporation at low voltage (<3 V) of continuous direct current (dc) power. Simulation results showed that an input voltage of only 1.5 V could generate an electric field intensity of about 1.17 kV cm(-1) across the cell suspension flow in the squeezed area. The electropermeation of yeast cell was observed, showing a permeabilization percentage up to 70%.

  1. Microfluidic geometric metering-based multi-reagent mixture generator for robust live cell screening array.

    PubMed

    Wang, Han; Kim, Jeongyun; Jayaraman, Arul; Han, Arum

    2014-12-01

    Microfluidic live cell arrays with integrated concentration gradient or mixture generators have been utilized in screening cellular responses to various biomolecular cues. Microfluidic network-based gradient generators that can create concentration gradients by repeatedly splitting and mixing different solutions using networks of serpentine channels are commonly used. However, in this method the generation of concentration gradients relies on the continuous flow of sample solutions at optimized flow rates, which poses challenges in maintaining the pressure and flow stability throughout the entire assay period. Here we present a microfluidic live cell screening array with an on-demand multi-reagent mixture generator where the mixing ratios, thus generated concentrations, are hard-wired into the chip itself through a geometric metering method. This platform showed significantly improved robustness and repeatability in generating concentration gradients of fluorescent dyes (average coefficient of variance C.V. = 9 %) compared to the conventional network-based gradient generators (average C.V. = 21 %). In studying the concentration dependent effects of the environmental toxicant 3-methylcholanthrene (3MC) on the activation of cytochrome P450 1A1 (Cyp 1A1) enzyme in H4IIE rat hepatoma cells, statistical variation of the Cyp 1A1 response was significantly lower (C.V. = 5 %) when using the developed mixture generator compared to that using the conventional gradient generator (C.V. = 12 %). Reduction in reagent consumption by 12-times was also achieved. This robust, accurate, and scalable multi-reagent mixture generator integrated with a cell culture array as a live cell assay platform can be readily implemented into various screening applications where repeatability, robustness, and low reagent consumptions over long periods of assay time are of importance.

  2. Approaching near real-time biosensing: microfluidic microsphere based biosensor for real-time analyte detection.

    PubMed

    Cohen, Noa; Sabhachandani, Pooja; Golberg, Alexander; Konry, Tania

    2015-04-15

    In this study we describe a simple lab-on-a-chip (LOC) biosensor approach utilizing well mixed microfluidic device and a microsphere-based assay capable of performing near real-time diagnostics of clinically relevant analytes such cytokines and antibodies. We were able to overcome the adsorption kinetics reaction rate-limiting mechanism, which is diffusion-controlled in standard immunoassays, by introducing the microsphere-based assay into well-mixed yet simple microfluidic device with turbulent flow profiles in the reaction regions. The integrated microsphere-based LOC device performs dynamic detection of the analyte in minimal amount of biological specimen by continuously sampling micro-liter volumes of sample per minute to detect dynamic changes in target analyte concentration. Furthermore we developed a mathematical model for the well-mixed reaction to describe the near real time detection mechanism observed in the developed LOC method. To demonstrate the specificity and sensitivity of the developed real time monitoring LOC approach, we applied the device for clinically relevant analytes: Tumor Necrosis Factor (TNF)-α cytokine and its clinically used inhibitor, anti-TNF-α antibody. Based on the reported results herein, the developed LOC device provides continuous sensitive and specific near real-time monitoring method for analytes such as cytokines and antibodies, reduces reagent volumes by nearly three orders of magnitude as well as eliminates the washing steps required by standard immunoassays.

  3. High-throughput screening of filamentous fungi using nanoliter-range droplet-based microfluidics

    NASA Astrophysics Data System (ADS)

    Beneyton, Thomas; Wijaya, I. Putu Mahendra; Postros, Prexilia; Najah, Majdi; Leblond, Pascal; Couvent, Angélique; Mayot, Estelle; Griffiths, Andrew D.; Drevelle, Antoine

    2016-06-01

    Filamentous fungi are an extremely important source of industrial enzymes because of their capacity to secrete large quantities of proteins. Currently, functional screening of fungi is associated with low throughput and high costs, which severely limits the discovery of novel enzymatic activities and better production strains. Here, we describe a nanoliter-range droplet-based microfluidic system specially adapted for the high-throughput sceening (HTS) of large filamentous fungi libraries for secreted enzyme activities. The platform allowed (i) compartmentalization of single spores in ~10 nl droplets, (ii) germination and mycelium growth and (iii) high-throughput sorting of fungi based on enzymatic activity. A 104 clone UV-mutated library of Aspergillus niger was screened based on α-amylase activity in just 90 minutes. Active clones were enriched 196-fold after a single round of microfluidic HTS. The platform is a powerful tool for the development of new production strains with low cost, space and time footprint and should bring enormous benefit for improving the viability of biotechnological processes.

  4. Recent advancements in chemical luminescence-based lab-on-chip and microfluidic platforms for bioanalysis.

    PubMed

    Mirasoli, Mara; Guardigli, Massimo; Michelini, Elisa; Roda, Aldo

    2014-01-01

    Miniaturization of analytical procedures through microchips, lab-on-a-chip or micro total analysis systems is one of the most recent trends in chemical and biological analysis. These systems are designed to perform all the steps in an analytical procedure, with the advantages of low sample and reagent consumption, fast analysis, reduced costs, possibility of extra-laboratory application. A range of detection technologies have been employed in miniaturized analytical systems, but most applications relied on fluorescence and electrochemical detection. Chemical luminescence (which includes chemiluminescence, bioluminescence, and electrogenerated chemiluminescence) represents an alternative detection principle that offered comparable (or better) analytical performance and easier implementation in miniaturized analytical devices. Nevertheless, chemical luminescence-based ones represents only a small fraction of the microfluidic devices reported in the literature, and until now no review has been focused on these devices. Here we review the most relevant applications (since 2009) of miniaturized analytical devices based on chemical luminescence detection. After a brief overview of the main chemical luminescence systems and of the recent technological advancements regarding their implementation in miniaturized analytical devices, analytical applications are reviewed according to the nature of the device (microfluidic chips, microchip electrophoresis, lateral flow- and paper-based devices) and the type of application (micro-flow injection assays, enzyme assays, immunoassays, gene probe hybridization assays, cell assays, whole-cell biosensors).

  5. Paper-based microfluidic devices for electrochemical immunofiltration analysis of human chorionic gonadotropin.

    PubMed

    Cao, Liangli; Fang, Cheng; Zeng, Ruosheng; Zhao, Xiongjie; Jiang, Yuren; Chen, Zhencheng

    2017-02-02

    An electrochemical immunofiltration analysis was introduced into microfluidic paper-based analytical devices (μPADs) for the first time, which was based on photolithography and screen-printing technology. The hydrophilic test zones of the aldehyde-functionalized screen-printed electrodes (SPEs) were biofunctionalized with capture antibodies (Ab1). A sensitive immune detection method was developed by using primary signal antibody functionalized gold nanoparticles (GNPs/Ab2) and alkaline phosphatase conjugated secondary antibody (ALP-IgG). Differential pulse voltammetry (DPV) was performed to detect the electrochemical response. The microfluidic paper-based electrochemical immunosensor (μ-PEI) was optimized and characterized for the detection of human chorionic gonadotropin (HCG), a model analyte, in a linear range from 1.0mIUmL(-1) to 100.0 IU mL(-1) with a detection limit of 0.36mIUmL(-1). Additionally, the proposed μ-PEI was used to test HCG in real human serum and obtained satisfactory results. The disposable, efficient, sensitive and low-cost μ-PEI has exhibited great potential for the development of point-of-care testing (POCT) devices that can be applicated in healthcare monitoring.

  6. High-throughput screening of filamentous fungi using nanoliter-range droplet-based microfluidics

    PubMed Central

    Beneyton, Thomas; Wijaya, I. Putu Mahendra; Postros, Prexilia; Najah, Majdi; Leblond, Pascal; Couvent, Angélique; Mayot, Estelle; Griffiths, Andrew D.; Drevelle, Antoine

    2016-01-01

    Filamentous fungi are an extremely important source of industrial enzymes because of their capacity to secrete large quantities of proteins. Currently, functional screening of fungi is associated with low throughput and high costs, which severely limits the discovery of novel enzymatic activities and better production strains. Here, we describe a nanoliter-range droplet-based microfluidic system specially adapted for the high-throughput sceening (HTS) of large filamentous fungi libraries for secreted enzyme activities. The platform allowed (i) compartmentalization of single spores in ~10 nl droplets, (ii) germination and mycelium growth and (iii) high-throughput sorting of fungi based on enzymatic activity. A 104 clone UV-mutated library of Aspergillus niger was screened based on α-amylase activity in just 90 minutes. Active clones were enriched 196-fold after a single round of microfluidic HTS. The platform is a powerful tool for the development of new production strains with low cost, space and time footprint and should bring enormous benefit for improving the viability of biotechnological processes. PMID:27270141

  7. MEMS and microfluidics for diagnostics devices.

    PubMed

    Rosen, Y; Gurman, P

    2010-06-01

    There are conditions in clinical medicine demanding critical therapeutic decisions. These conditions necessitate accuracy, rapidity, accessibility, cost-effectiveness and mobility. New technologies have been developed in order to address these challenges. Microfluidics and Micro Electro-Mechanical Systems are two of such technologies. Microfluidics, a discipline that involves processing fluids at the microscale in etched microchannels, is being used to build lab- on-a-chip systems to run chemical and biological assays. These systems are being transformed into handheld devices designed to be used at remote settings or at the bedside. MEMS are microscale electromechanical elements integrated in lab chip systems or used as individual components. MEMS based sensors represents a highly developed field with successful commercialized products currently being incorporated into vitro,ex vivo and in vivo devices. In the present paper several examples of microfluidic devices and MEMS sensors are introduced together with some current examples of commercialized products. Future challenges and trends will be discussed.

  8. Microfluidic serpentine antennas with designed mechanical tunability.

    PubMed

    Huang, YongAn; Wang, Yezhou; Xiao, Lin; Liu, Huimin; Dong, Wentao; Yin, Zhouping

    2014-11-07

    This paper describes the design and characterization of microfluidic serpentine antennas with reversible stretchability and designed mechanical frequency modulation (FM). The microfluidic antennas are designed based on the Poisson's ratio of the elastomer in which the liquid alloy antenna is embedded, to controllably decrease, stabilize or increase its resonance frequency when being stretched. Finite element modelling was used in combination with experimental verification to investigate the effects of substrate dimensions and antenna aspect ratios on the FM sensitivity to uniaxial stretching. It could be designed within the range of -1.2 to 0.6 GHz per 100% stretch. When the aspect ratio of the serpentine antenna is between 1.0 and 1.5, the resonance frequency is stable under stretching, bending, and twisting. The presented microfluidic serpentine antenna design could be utilized in the field of wireless mobile communication for the design of wearable electronics, with a stable resonance frequency under dynamic applied strain up to 50%.

  9. Hot embossed polyethylene through-hole chips for bead-based microfluidic devices

    PubMed Central

    Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N.; Christodoulides, Nicolaos; McDevitt, John T.

    2013-01-01

    Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications forces cost considerations to be kept low and throughput high. As such, a materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 minutes with the ability to scale up 4x by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby

  10. Hot embossed polyethylene through-hole chips for bead-based microfluidic devices.

    PubMed

    Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N; Christodoulides, Nicolaos; McDevitt, John T

    2013-04-15

    Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications force cost considerations to be kept low and throughput high. As such, materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 min with the ability to scale up 4 times by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby

  11. A PDMS-Based Cylindrical Hybrid Lens for Enhanced Fluorescence Detection in Microfluidic Systems

    PubMed Central

    Lin, Bor-Shyh; Yang, Yu-Ching; Ho, Chong-Yi; Yang, Han-Yu; Wang, Hsiang-Yu

    2014-01-01

    Microfluidic systems based on fluorescence detection have been developed and applied for many biological and chemical applications. Because of the tiny amount of sample in the system; the induced fluorescence can be weak. Therefore, most microfluidic systems deploy multiple optical components or sophisticated equipment to enhance the efficiency of fluorescence detection. However, these strategies encounter common issues of complex manufacturing processes and high costs. In this study; a miniature, cylindrical and hybrid lens made of polydimethylsiloxane (PDMS) to improve the fluorescence detection in microfluidic systems is proposed. The hybrid lens integrates a laser focusing lens and a fluorescence collecting lens to achieve dual functions and simplify optical setup. Moreover, PDMS has advantages of low-cost and straightforward fabrication compared with conventional optical components. The performance of the proposed lens is first examined with two fluorescent dyes and the results show that the lens provides satisfactory enhancement for fluorescence detection of Rhodamine 6G and Nile Red. The overall increments in collected fluorescence signal and detection sensitivity are more than 220% of those without lens, and the detection limits of Rhodamine 6G and Nile red are lowered to 0.01 μg/mL and 0.05 μg/mL, respectively. The hybrid lens is further applied to the detection of Nile red-labeled Chlorella vulgaris cells and it increases both signal intensity and detection sensitivity by more than 520%. The proposed hybrid lens also dramatically reduces the variation in detected signal caused by the deviation in incident angle of excitation light. PMID:24531300

  12. Electrochemical microfluidic chip based on molecular imprinting technique applied for therapeutic drug monitoring.

    PubMed

    Liu, Jiang; Zhang, Yu; Jiang, Min; Tian, Liping; Sun, Shiguo; Zhao, Na; Zhao, Feilang; Li, Yingchun

    2017-05-15

    In this work, a novel electrochemical detection platform was established by integrating molecularly imprinting technique with microfluidic chip and applied for trace measurement of three therapeutic drugs. The chip foundation is acrylic panel with designed grooves. In the detection cell of the chip, a Pt wire is used as the counter electrode and reference electrode, and a Au-Ag alloy microwire (NPAMW) with 3D nanoporous surface modified with electro-polymerized molecularly imprinted polymer (MIP) film as the working electrode. Detailed characterization of the chip and the working electrode was performed, and the properties were explored by cyclic voltammetry and electrochemical impedance spectroscopy. Two methods, respectively based on electrochemical catalysis and MIP/gate effect were employed for detecting warfarin sodium by using the prepared chip. The linearity of electrochemical catalysis method was in the range of 5×10(-6)-4×10(-4)M, which fails to meet clinical testing demand. By contrast, the linearity of gate effect was 2×10(-11)-4×10(-9)M with remarkably low detection limit of 8×10(-12)M (S/N=3), which is able to satisfy clinical assay. Then the system was applied for 24-h monitoring of drug concentration in plasma after administration of warfarin sodium in rabbit, and the corresponding pharmacokinetic parameters were obtained. In addition, the microfluidic chip was successfully adopted to analyze cyclophosphamide and carbamazepine, implying its good versatile ability. It is expected that this novel electrochemical microfluidic chip can act as a promising format for point-of-care testing via monitoring different analytes sensitively and conveniently.

  13. Rapid detection of tuberculosis using droplet-based microfluidics

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Liat; Cheng, Yunfeng; Rao, Jianghong; Tang, Sindy K. Y.

    2014-03-01

    Tuberculosis is one of the most deadly diseases that kills over one million people each year and infects one-third of the world's population. The disease is spread by infection with Mycobacterium tuberculosis (Mtb). Owing to its airborne transmission, early diagnosis is critical to the prevention and control of TB. Standard diagnostic methods, acid-fast smear from sputum, often do not become positive until after transmission occurs, which allows the spread of the disease. Culture-based techniques are more sensitive, but take weeks to obtain results because of the extremely slow growth rate of Mtb. In this study a new method to detect indicator enzyme based on the isolation of tubercle bacillus in a large number of picoliter droplets combined with a fluorescent probe has been developed. We use BlaC (an enzyme naturally expressed/secreted by tubercle bacilli) as a marker and a designed BlaC-specific fluorogenic substrates as probes for Mtb detection. We present here a new method to detect the indicator enzyme based on the isolation, digitization and concentration of bacteria samples in a large number of picoliter drops. We show that by controlling the size of the droplets we can control the rate of conversion. Hence rapid increase in signal has been observed as the size of the drops has been decreased. Our vision is that this tool will be able to detect tubercle bacilli in a sensitive, rapid, specific and quantitative manner in vitro at a low cost, particularly in resource limited settings where TB is the most prevalent.

  14. Implementation of poly(ε-caprolactone) sheet-based shape-memory polymer microvalves into plastic-based microfluidic devices

    NASA Astrophysics Data System (ADS)

    Jiang, Chenyang; Uto, Koichiro; Ebara, Mitsuhiro; Aoyagi, Takao; Ichiki, Takanori

    2015-06-01

    Implementation of shape-memory polymer (SMP) sheet-based microvalves into plastic-based microfluidic devices has been studied toward the use in disposable and mass producible micro total analysis devices. Poly(ε-caprolactone) (PCL) and poly(methyl methacrylate-co-styrene) (MS) were used as SMP and main substrate materials, respectively. Bonding between PCL sheets and MS plates was the critical issue in the practical implementation. We found the pristine PCL sheet has relatively rough surface with Ra of 85.14 nm, which is the cause of poor bonding. Hence, by introducing the post-anneal treatment with sandwiched between two flat glass plates, the PCL surface could be smoothed to Ra of 12.50 nm, and tight bonding could be obtained. Consequently, microfluidic devices consisting of plastic/PCL/plastic layers were successfully fabricated and therein the actuation of SMP valves without any leakage was demonstrated. The present technology is expected to be applicable to disposable microfluidic devices as required for point-of-care testing.

  15. Acid-base titrations using microfluidic paper-based analytical devices.

    PubMed

    Karita, Shingo; Kaneta, Takashi

    2014-12-16

    Rapid and simple acid-base titration was accomplished using a novel microfluidic paper-based analytical device (μPAD). The μPAD was fabricated by wax printing and consisted of ten reservoirs for reaction and detection. The reaction reservoirs contained various amounts of a primary standard substance, potassium hydrogen phthalate (KHPth), whereas a constant amount of phenolphthalein was added to all the detection reservoirs. A sample solution containing NaOH was dropped onto the center of the μPAD and was allowed to spread to the reaction reservoirs where the KHPth neutralized it. When the amount of NaOH exceeded that of the KHPth in the reaction reservoirs, unneutralized hydroxide ion penetrated the detection reservoirs, resulting in a color reaction from the phenolphthalein. Therefore, the number of the detection reservoirs with no color change determined the concentration of the NaOH in the sample solution. The titration was completed within 1 min by visually determining the end point, which required neither instrumentation nor software. The volumes of the KHPth and phenolphthalein solutions added to the corresponding reservoirs were optimized to obtain reproducible and accurate results for the concentration of NaOH. The μPADs determined the concentration of NaOH at orders of magnitude ranging from 0.01 to 1 M. An acid sample, HCl, was also determined using Na2CO3 as a primary standard substance instead of KHPth. Furthermore, the μPAD was applicable to the titrations of nitric acid, sulfuric acid, acetic acid, and ammonia solutions. The μPADs were stable for more than 1 month when stored in darkness at room temperature, although this was reduced to only 5 days under daylight conditions. The analysis of acidic hot spring water was also demonstrated in the field using the μPAD, and the results agreed well with those obtained by classic acid-base titration.

  16. Automated microfluidic platform of bead-based electrochemical immunosensor integrated with bioreactor for continual monitoring of cell secreted biomarkers.

    PubMed

    Riahi, Reza; Shaegh, Seyed Ali Mousavi; Ghaderi, Masoumeh; Zhang, Yu Shrike; Shin, Su Ryon; Aleman, Julio; Massa, Solange; Kim, Duckjin; Dokmeci, Mehmet Remzi; Khademhosseini, Ali

    2016-04-21

    There is an increasing interest in developing microfluidic bioreactors and organs-on-a-chip platforms combined with sensing capabilities for continual monitoring of cell-secreted biomarkers. Conventional approaches such as ELISA and mass spectroscopy cannot satisfy the needs of continual monitoring as they are labor-intensive and not easily integrable with low-volume bioreactors. This paper reports on the development of an automated microfluidic bead-based electrochemical immunosensor for in-line measurement of cell-secreted biomarkers. For the operation of the multi-use immunosensor, disposable magnetic microbeads were used to immobilize biomarker-recognition molecules. Microvalves were further integrated in the microfluidic immunosensor chip to achieve programmable operations of the immunoassay including bead loading and unloading, binding, washing, and electrochemical sensing. The platform allowed convenient integration of the immunosensor with liver-on-chips to carry out continual quantification of biomarkers secreted from hepatocytes. Transferrin and albumin productions were monitored during a 5-day hepatotoxicity assessment in which human primary hepatocytes cultured in the bioreactor were treated with acetaminophen. Taken together, our unique microfluidic immunosensor provides a new platform for in-line detection of biomarkers in low volumes and long-term in vitro assessments of cellular functions in microfluidic bioreactors and organs-on-chips.

  17. Automated microfluidic platform of bead-based electrochemical immunosensor integrated with bioreactor for continual monitoring of cell secreted biomarkers

    NASA Astrophysics Data System (ADS)

    Riahi, Reza; Shaegh, Seyed Ali Mousavi; Ghaderi, Masoumeh; Zhang, Yu Shrike; Shin, Su Ryon; Aleman, Julio; Massa, Solange; Kim, Duckjin; Dokmeci, Mehmet Remzi; Khademhosseini, Ali

    2016-04-01

    There is an increasing interest in developing microfluidic bioreactors and organs-on-a-chip platforms combined with sensing capabilities for continual monitoring of cell-secreted biomarkers. Conventional approaches such as ELISA and mass spectroscopy cannot satisfy the needs of continual monitoring as they are labor-intensive and not easily integrable with low-volume bioreactors. This paper reports on the development of an automated microfluidic bead-based electrochemical immunosensor for in-line measurement of cell-secreted biomarkers. For the operation of the multi-use immunosensor, disposable magnetic microbeads were used to immobilize biomarker-recognition molecules. Microvalves were further integrated in the microfluidic immunosensor chip to achieve programmable operations of the immunoassay including bead loading and unloading, binding, washing, and electrochemical sensing. The platform allowed convenient integration of the immunosensor with liver-on-chips to carry out continual quantification of biomarkers secreted from hepatocytes. Transferrin and albumin productions were monitored during a 5-day hepatotoxicity assessment in which human primary hepatocytes cultured in the bioreactor were treated with acetaminophen. Taken together, our unique microfluidic immunosensor provides a new platform for in-line detection of biomarkers in low volumes and long-term in vitro assessments of cellular functions in microfluidic bioreactors and organs-on-chips.

  18. Microfluidic magnetic switching valves based on aggregates of magnetic nanoparticles: Effects of aggregate length and nanoparticle sizes

    NASA Astrophysics Data System (ADS)

    Jiemsakul, Thanakorn; Manakasettharn, Supone; Kanharattanachai, Sivakorn; Wanna, Yongyuth; Wangsuya, Sujint; Pratontep, Sirapat

    2017-01-01

    We demonstrate microfluidic switching valves using magnetic nanoparticles blended within the working fluid as an alternative microfluidic flow control in microchannels. Y-shaped microchannels have been fabricated by using a CO2 laser cutter to pattern microchannels on transparent poly(methyl methacrylate) (PMMA) sheets covered with thermally bonded transparent polyvinyl chloride (PVC) sheets. To examine the performance of the microfluidic magnetic switching valves, an aqueous magnetic nanoparticle suspension was injected into the microchannels by a syringe pump. Neodymium magnets were then employed to attract magnetic nanoparticles and form an aggregate that blocked the microchannels at a required position. We have found that the maximum volumetric flow rate of the syringe pump that the magnetic nanoparticle aggregate can withstand scales with the square of the external magnetic flux density. The viscosity of the fluid exhibits dependent on the aggregate length and the size of the magnetic nanoparticles. This microfluidic switching valve based on aggregates of magnetic nanoparticles has strong potentials as an on-demand flow control, which may help simplifying microfluidic channel designs.

  19. Automated microfluidic platform of bead-based electrochemical immunosensor integrated with bioreactor for continual monitoring of cell secreted biomarkers

    PubMed Central

    Riahi, Reza; Shaegh, Seyed Ali Mousavi; Ghaderi, Masoumeh; Zhang, Yu Shrike; Shin, Su Ryon; Aleman, Julio; Massa, Solange; Kim, Duckjin; Dokmeci, Mehmet Remzi; Khademhosseini, Ali

    2016-01-01

    There is an increasing interest in developing microfluidic bioreactors and organs-on-a-chip platforms combined with sensing capabilities for continual monitoring of cell-secreted biomarkers. Conventional approaches such as ELISA and mass spectroscopy cannot satisfy the needs of continual monitoring as they are labor-intensive and not easily integrable with low-volume bioreactors. This paper reports on the development of an automated microfluidic bead-based electrochemical immunosensor for in-line measurement of cell-secreted biomarkers. For the operation of the multi-use immunosensor, disposable magnetic microbeads were used to immobilize biomarker-recognition molecules. Microvalves were further integrated in the microfluidic immunosensor chip to achieve programmable operations of the immunoassay including bead loading and unloading, binding, washing, and electrochemical sensing. The platform allowed convenient integration of the immunosensor with liver-on-chips to carry out continual quantification of biomarkers secreted from hepatocytes. Transferrin and albumin productions were monitored during a 5-day hepatotoxicity assessment in which human primary hepatocytes cultured in the bioreactor were treated with acetaminophen. Taken together, our unique microfluidic immunosensor provides a new platform for in-line detection of biomarkers in low volumes and long-term in vitro assessments of cellular functions in microfluidic bioreactors and organs-on-chips. PMID:27098564

  20. Paper-based microfluidic biofuel cell operating under glucose concentrations within physiological range.

    PubMed

    González-Guerrero, Maria José; Del Campo, F Javier; Esquivel, Juan Pablo; Leech, Dónal; Sabaté, Neus

    2017-04-15

    This work addresses the development of a compact paper-based enzymatic microfluidic glucose/O2 fuel cell that can operate using a very limited sample volume (≈35µl) and explores the energy generated by glucose at concentrations typically found in blood samples at physiological conditions (pH 7.4). Carbon paper electrodes combined with a paper sample absorption substrate all contained within a plastic microfluidic casing are used to construct the paper-based fuel cell. The anode catalysts consist of glucose dehydrogenase and [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly-vinylimidazole)10Cl](+) as mediator, while the cathode catalysts were bilirubin oxidase and [Os(2,2'-bipyridine)2(poly-vinylimidazole)10Cl](+) as mediator. The fuel cell delivered a linear power output response to glucose over the range of 2.5-30mM, with power densities ranging from 20 to 90µWcm(-2). The quantification of the available electrical power as well as the energy density extracted from small synthetic samples allows planning potential uses of this energy to power different sensors and analysis devices in a wide variety of in-vitro applications.

  1. Multiplexed Affinity-Based Separation of Proteins and Cells Using Inertial Microfluidics

    PubMed Central

    Sarkar, Aniruddh; Hou, Han Wei; Mahan, Alison. E.; Han, Jongyoon; Alter, Galit

    2016-01-01

    Isolation of low abundance proteins or rare cells from complex mixtures, such as blood, is required for many diagnostic, therapeutic and research applications. Current affinity-based protein or cell separation methods use binary ‘bind-elute’ separations and are inefficient when applied to the isolation of multiple low-abundance proteins or cell types. We present a method for rapid and multiplexed, yet inexpensive, affinity-based isolation of both proteins and cells, using a size-coded mixture of multiple affinity-capture microbeads and an inertial microfluidic particle sorter device. In a single binding step, different targets–cells or proteins–bind to beads of different sizes, which are then sorted by flowing them through a spiral microfluidic channel. This technique performs continuous-flow, high throughput affinity-separation of milligram-scale protein samples or millions of cells in minutes after binding. We demonstrate the simultaneous isolation of multiple antibodies from serum and multiple cell types from peripheral blood mononuclear cells or whole blood. We use the technique to isolate low abundance antibodies specific to different HIV antigens and rare HIV-specific cells from blood obtained from HIV+ patients. PMID:27026280

  2. A microfluidic system for evaluation of antioxidant capacity based on a peroxyoxalate chemiluminescence assay.

    PubMed

    Amatatongchai, Maliwan; Hofmann, Oliver; Nacapricha, Duangjai; Chailapakul, Orawon; deMello, Andrew J

    2007-01-01

    A microfluidic system incorporating chemiluminescence detection is reported as a new tool for measuring antioxidant capacity. The detection is based on a peroxyoxalate chemiluminescence (PO-CL) assay with 9,10-bis-(phenylethynyl)anthracene (BPEA) as the fluorescent probe and hydrogen peroxide as the oxidant. Antioxidant plugs injected into the hydrogen peroxide stream result in inhibition of the CL emission which can be quantified and correlated with antioxidant capacity. The PO-CL assay is performed in 800-microm-wide and 800-microm-deep microchannels on a poly(dimethylsiloxane) (PDMS) microchip. Controlled injection of the antioxidant plugs is performed through an injection valve. Of the plant-food based antioxidants tested, beta-carotene was found to be the most efficient hydrogen peroxide scavenger (SAHP of 3.27x10(-3) micromol-1 L), followed by alpha-tocopherol (SAHP of 2.36x10(-3) micromol-1 L) and quercetin (SAHP of 0.31x10(-3) micromol-1 L). Although the method is inherently simple and rapid, excellent analytical performance is afforded in terms of sensitivity, dynamic range, and precision, with RSD values typically below 1.5%. We expect our microfluidic devices to be used for in-the-field antioxidant capacity screening of plant-sourced food and pharmaceutical supplements.

  3. Three-dimensional paper-based microfluidic device for assays of protein and glucose in urine.

    PubMed

    Sechi, Deidre; Greer, Brady; Johnson, Jesse; Hashemi, Nastaran

    2013-11-19

    The first step in curing a disease is being able to detect the disease effectively. Paper-based microfluidic devices are biodegradable and can make diagnosing diseases cost-effective and easy in almost all environments. We created a three-dimesnional (3D) paper device using wax printing fabrication technique and basic principles of origami. This design allows for a versatile fabrication technique over previously reported patterning of SU-8 photoresist on chromatography paper by employing a readily available wax printer. The design also utilizes multiple colorimetric assays that can accommodate one or more analytes including urine, blood, and saliva. In this case to demonstrate the functionality of the 3D paper-based microfluidic system, a urinalysis of protein and glucose assays is conducted. The amounts of glucose and protein introduced to the device are found to be proportional to the color change of each assay. This color change was quantified by use of Adobe Photoshop. Urine samples from participants with no pre-existing health conditions and one person with diabetes were collected and compared against synthetic urine samples with predetermined glucose and protein levels. Utilizing this method, we were able to confirm that both protein and glucose levels were in fact within healthy ranges for healthy participants. For the participant with diabetes, glucose was found to be above the healthy range while the protein level was in the healthy range.

  4. Enhancing Capillary-Driven Flow for Paper-Based Microfluidic Channels.

    PubMed

    Songok, Joel; Toivakka, Martti

    2016-11-09

    Paper-based microfluidic devices have received considerable interest due to their benefits with regards to low manufacturing costs, simplicity, and the wide scope of applications. However, limitations including sample retention in paper matrix and evaporation as well as low liquid flow rates have often been overlooked. This paper presents a paper-based capillary-driven flow system that speeds up flow rates by utilizing narrow gap geometry between two parallel surfaces separated by a spacer. The top surface is hydrophobic, while the bottom surface is a hydrophobic paper substrate with a microfluidic channel defined by a hydrophilic pathway, leaving sides of the channel open to air. The liquid flows on the hydrophilic path in the gap without spreading onto the hydrophobic regions. The closed-channel flow system showed higher spreading distances and accelerated liquid flow. An average flow rate increases of 200 and 100% were obtained for the nanoparticle-coated paperboard and the blotting papers used, respectively. Fast liquid delivery to detection zones or reaction implies rapid results from analytical devices. In addition, liquid drying and evaporation can be reduced in the proposed closed-channel system.

  5. Continuous nanoparticle production by microfluidic-based emulsion, mixing and crystallization

    SciTech Connect

    Su, Y.-F. Kim, H.; Kovenklioglu, S.; Lee, W.Y.

    2007-09-15

    BaSO{sub 4} and 2,2'-dipyridylamine (DPA) nanoparticles were synthesized as reactive crystallization and anti-solvent recrystallization examples, respectively, of using the microfluidic-based emulsion and mixing approach as a new avenue of continuously producing inorganic and organic nanoparticles. BaSO{sub 4} nanoparticles in the size range of 15-100 nm were reactively precipitated within the confinement of an aqueous droplet which was coalesced from two separate aqueous droplets containing BaCl{sub 2} and (NH{sub 4}){sub 2}SO{sub 4} using a three T-junction micromixer configuration constructed with commercially available simple tubing and fitting supplies. Also, DPA nanoparticles of about 200 nm were crystallized by combining DPA+ethanol and water droplets using the same micromixer configuration. - Graphical abstract: BaSO{sub 4} and 2,2'-dipyridylamine (DPA) nanoparticles were synthesized as reactive crystallization and anti-solvent recrystallization examples, respectively, of using the microfluidic-based emulsion and mixing approach as a new avenue of continuously producing inorganic and organic nanoparticles.

  6. Synergism between particle-based multiplexing and microfluidics technologies may bring diagnostics closer to the patient.

    PubMed

    Derveaux, S; Stubbe, B G; Braeckmans, K; Roelant, C; Sato, K; Demeester, J; De Smedt, S C

    2008-08-01

    In the field of medical diagnostics there is a growing need for inexpensive, accurate, and quick high-throughput assays. On the one hand, recent progress in microfluidics technologies is expected to strongly support the development of miniaturized analytical devices, which will speed up (bio)analytical assays. On the other hand, a higher throughput can be obtained by the simultaneous screening of one sample for multiple targets (multiplexing) by means of encoded particle-based assays. Multiplexing at the macro level is now common in research labs and is expected to become part of clinical diagnostics. This review aims to debate on the "added value" we can expect from (bio)analysis with particles in microfluidic devices. Technologies to (a) decode, (b) analyze, and (c) manipulate the particles are described. Special emphasis is placed on the challenges of integrating currently existing detection platforms for encoded microparticles into microdevices and on promising microtechnologies that could be used to down-scale the detection units in order to obtain compact miniaturized particle-based multiplexing platforms.

  7. Battery-triggered microfluidic paper-based multiplex electrochemiluminescence immunodevice based on potential-resolution strategy.

    PubMed

    Wang, Shaowei; Ge, Lei; Zhang, Yan; Song, Xianrang; Li, Nianqiang; Ge, Shenguang; Yu, Jinghua

    2012-11-07

    A potential-resolution strategy for multiplex electrochemiluminescence (ECL) immunoassay on a microfluidic paper-based analytical device (μ-PAD) was demonstrated for the first time, using tris-(bipyridine)-ruthenium(ii) (Ru(bpy)(3)(2+)) and carbon nanodots (CNDs) as the ECL labels for high-throughput ECL immunoassay on μ-PAD. Based on this strategy, simultaneous detection of four tumor markers using only two screen-printed carbon working electrodes (one electrode for two analytes) on an immunodevice consisting of a piece of patterned paper (denoted as μ-PECLI in this work) was realized, which is a simplification of the configuration of traditional μ-PADs. As a further development of μ-PECLI in low-cost and disposable applications, battery-triggered (constant-potential) ECL detection on μ-PECLI was developed, allowing the traditional electrochemical workstation to be abandoned. In addition, to exactly control the output voltage of the battery, a low-cost and simple voltage-controller was designed and fabricated for the first time. The battery-triggered ECL immunoassay principle on μ-PECLI is explained. We found that the simultaneous determination of two analytes in one paper working zone could be achieved by controlling the operational constant-potential (+1.2 V for Ru(bpy)(3)(2+) labels and -1.2 V for CNDs labels (vs. Ag/AgCl auxiliary electrode)) by simply reversing the connection mode. Finally, four tumor markers in human serum samples from the Tumor Hospital were assayed and the results obtained were in acceptable agreement with the reference values from parallel single-analyte test. This battery-triggered μ-PECLI provides a new strategy for high-throughput, low-cost, sensitive, automated and simultaneous multiplex immunoassay and point-of-care diagnosis.

  8. Microfluidic Flame Barrier

    NASA Technical Reports Server (NTRS)

    Mungas, Gregory S. (Inventor); Fisher, David J. (Inventor); Mungas, Christopher (Inventor)

    2013-01-01

    Propellants flow through specialized mechanical hardware that is designed for effective and safe ignition and sustained combustion of the propellants. By integrating a micro-fluidic porous media element between a propellant feed source and the combustion chamber, an effective and reliable propellant injector head may be implemented that is capable of withstanding transient combustion and detonation waves that commonly occur during an ignition event. The micro-fluidic porous media element is of specified porosity or porosity gradient selected to be appropriate for a given propellant. Additionally the propellant injector head design integrates a spark ignition mechanism that withstands extremely hot running conditions without noticeable spark mechanism degradation.

  9. Microfluidic device based on a micro-hydrocyclone for particle-liquid separation.

    PubMed

    Bhardwaj, P; Bagdi, P; Sen, A K

    2011-12-07

    This paper presents theoretical analysis, design, simulation, fabrication and test of a microfluidic device ('Micro-hydrocyclone') for separation of micron and submicron size solid particles from liquid in a particle liquid mixture. A theoretical analysis of the micro-hydrocyclone is performed to understand the physics and develop suitable design models. The structure of the proposed device is designed based on the Bradley model, as it offers lower cut-size thus making it suitable for microfluidics applications. The operational parameters are derived from the dimensional group model. The particle separation process inside the micro-hydrocyclone is simulated by solving fluid flows using Navier-Stokes equations and particle dynamics using a Lagrangian approach in a Eulerian fluid. The influence of inlet velocity and density on separation efficiency is investigated. The device is fabricated with SU-8 photoresist on a PMMA substrate using a combination of photolithography and micro-milling. Experiments are performed to demonstrate particle-liquid separation using polystyrene microbeads suspended in PBS as the feed sample. The influence of inlet velocity and particle size on particle separation efficiency is measured and compared with that obtained from simulations and a good match was found. The proposed device can be easily integrated with micro-environments thus it is suitable for lab-on-chip and microsystems development. The device may have applications in chemical analysis, materials research, point-of-care, blood sample preparation and other biomedical applications.

  10. A Microfluidic Love-Wave Biosensing Device for PSA Detection Based on an Aptamer Beacon Probe.

    PubMed

    Zhang, Feng; Li, Shuangming; Cao, Kang; Wang, Pengjuan; Su, Yan; Zhu, Xinhua; Wan, Ying

    2015-06-11

    A label-free and selective aptamer beacon-based Love-wave biosensing device was developed for prostate specific antigen (PSA) detection. The device consists of the following parts: LiTaO3 substrate with SiO2 film as wave guide layer, two set of inter-digital transducers (IDT), gold film for immobilization of the biorecongniton layer and a polydimethylsiloxane (PDMS) microfluidic channels. DNA aptamer, or "artificial antibody", was used as the specific biorecognition probe for PSA capture. Some nucleotides were added to the 3'-end of the aptamer to form a duplex with the 3'-end, turning the aptamer into an aptamer-beacon. Taking advantage of the selective target-induced assembly changes arising from the "aptamer beacon", highly selective and specific detection of PSA was achieved. Furthermore, PDMS microfluidic channels were designed and fabricated to realize automated quantitative sample injection. After optimization of the experimental conditions, the established device showed good performance for PSA detection between 10 ng/mL to 1 μg/mL, with a detection limit of 10 ng/mL. The proposed sensor might be a promising alternative for point of care diagnostics.

  11. Microfluidics-Based Single-Cell Functional Proteomics for Fundamental and Applied Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Yu, Jing; Zhou, Jing; Sutherland, Alex; Wei, Wei; Shin, Young Shik; Xue, Min; Heath, James R.

    2014-06-01

    We review an emerging microfluidics-based toolkit for single-cell functional proteomics. Functional proteins include, but are not limited to, the secreted signaling proteins that can reflect the biological behaviors of immune cells or the intracellular phosphoproteins associated with growth factor-stimulated signaling networks. Advantages of the microfluidics platforms are multiple. First, 20 or more functional proteins may be assayed simultaneously from statistical numbers of single cells. Second, cell behaviors (e.g., motility) may be correlated with protein assays. Third, extensions to quantized cell populations can permit measurements of cell-cell interactions. Fourth, rare cells can be functionally identified and then separated for further analysis or culturing. Finally, certain assay types can provide a conduit between biology and the physicochemical laws. We discuss the history and challenges of the field then review design concepts and uses of the microchip platforms that have been reported, with an eye toward biomedical applications. We then look to the future of the field.

  12. Microfluidics-based single-cell functional proteomics for fundamental and applied biomedical applications.

    PubMed

    Yu, Jing; Zhou, Jing; Sutherland, Alex; Wei, Wei; Shin, Young Shik; Xue, Min; Heath, James R

    2014-01-01

    We review an emerging microfluidics-based toolkit for single-cell functional proteomics. Functional proteins include, but are not limited to, the secreted signaling proteins that can reflect the biological behaviors of immune cells or the intracellular phosphoproteins associated with growth factor-stimulated signaling networks. Advantages of the microfluidics platforms are multiple. First, 20 or more functional proteins may be assayed simultaneously from statistical numbers of single cells. Second, cell behaviors (e.g., motility) may be correlated with protein assays. Third, extensions to quantized cell populations can permit measurements of cell-cell interactions. Fourth, rare cells can be functionally identified and then separated for further analysis or culturing. Finally, certain assay types can provide a conduit between biology and the physicochemical laws. We discuss the history and challenges of the field then review design concepts and uses of the microchip platforms that have been reported, with an eye toward biomedical applications. We then look to the future of the field.

  13. Ionogel-based light-actuated valves for controlling liquid flow in micro-fluidic manifolds.

    PubMed

    Benito-Lopez, Fernando; Byrne, Robert; Răduţă, Ana Maria; Vrana, Nihal Engin; McGuinness, Garrett; Diamond, Dermot

    2010-01-21

    We present the fabrication, characterisation and performance of four novel ionic liquid polymer gels (ionogels) as photo-actuated valves incorporated into micro-fluidic manifolds. The ionogels incorporate benzospiropyran units and phosphonium-based ionic liquids. Each ionogel is photo-polymerised in situ in the channels of a poly(methyl methacrylate) micro-fluidic device, generating a manifold incorporating four different micro-valves. The valves are actuated by simply applying localised white light irradiation, meaning that no physical contact between the actuation impulse (light) and the valve structure is required. Through variation of the composition of the ionogels, each of the micro-valves can be tuned to open at different times under similar illumination conditions. Therefore, flows through the manifold can be independently controlled by a single light source. At present, the contraction process to open the channel is relatively rapid (seconds) while the recovery (expansion) process to re-close the channel is relatively slow (minutes), meaning that the valve, in its current form, is better suited for single-actuation events.

  14. High-resolution dose-response screening using droplet-based microfluidics.

    PubMed

    Miller, Oliver J; El Harrak, Abdeslam; Mangeat, Thomas; Baret, Jean-Christophe; Frenz, Lucas; El Debs, Bachir; Mayot, Estelle; Samuels, Michael L; Rooney, Eamonn K; Dieu, Pierre; Galvan, Martin; Link, Darren R; Griffiths, Andrew D

    2012-01-10

    A critical early step in drug discovery is the screening of a chemical library. Typically, promising compounds are identified in a primary screen and then more fully characterized in a dose-response analysis with 7-10 data points per compound. Here, we describe a robust microfluidic approach that increases the number of data points to approximately 10,000 per compound. The system exploits Taylor-Aris dispersion to create concentration gradients, which are then segmented into picoliter microreactors by droplet-based microfluidics. The large number of data points results in IC(50) values that are highly precise (± 2.40% at 95% confidence) and highly reproducible (CV = 2.45%, n = 16). In addition, the high resolution of the data reveals complex dose-response relationships unambiguously. We used this system to screen a chemical library of 704 compounds against protein tyrosine phosphatase 1B, a diabetes, obesity, and cancer target. We identified a number of novel inhibitors, the most potent being sodium cefsulodine, which has an IC(50) of 27 ± 0.83 μM.

  15. Surface Roughness Study on Microchannels of CO2 Laser Fabricating Pmma-Based Microfluidic Chip

    NASA Astrophysics Data System (ADS)

    Chen, Xueye; Li, Tiechuan; Fu, Baoding

    A novel method named soak sacrificial layer ultrasonic method (SSLUM) has been presented for optimizing the surface roughness of the microchannels of polymethyl methacrylate (PMMA)-based microfluidic chips. CO2 laser was used for ablative microchannels on the PMMA sheet, and the effects of key parameters including laser power, laser ablation speed and solution concentration on the surface roughness of microchannels were estimated and optimized by SSLUM. The experimental observation demonstrates that the surface roughness results mainly from the residues on the channel wall, which are produced by the bubbles movement and bursting. The research results show that the surface roughness can be improved effectively by using SSLUM. In our experiment, the best value was Ra = 110nm with laser power 12W, laser ablation speed 10mm/s, the solution concentration 75%, and the time of ultrasonic vibration 25min. SSLUM is proven to be an effective, simple and rapid method for optimizing the surface roughness of microchannels of microfluidic chips.

  16. An integrated hybrid microfluidic device for oviposition-based chemical screening of adult Drosophila melanogaster.

    PubMed

    Leung, Jacob C K; Hilliker, Arthur J; Rezai, Pouya

    2016-02-21

    Chemical screening using Drosophila melanogaster (the fruit fly) is vital in drug discovery, agricultural, and toxicological applications. Oviposition (egg laying) on chemically-doped agar plates is an important read-out metric used to quantitatively assess the biological fitness and behavioral responses of Drosophila. Current oviposition-based chemical screening studies are inaccurate, labor-intensive, time-consuming, and inflexible due to the manual chemical doping of agar. In this paper, we have developed a novel hybrid agar-polydimethylsiloxane (PDMS) microfluidic device for single- and multi-concentration chemical dosing and on-chip oviposition screening of free-flying adult stage Drosophila. To achieve this, we have devised a novel technique to integrate agar with PDMS channels using ice as a sacrificial layer. Subsequently, we have conducted single-chemical toxicity and multiple choice chemical preference assays on adult Drosophila melanogaster using zinc and acetic acid at various concentrations. Our device has enabled us to 1) demonstrate that Drosophila is capable of sensing the concentration of different chemicals on a PDMS-agar microfluidic device, which plays significant roles in determining oviposition site selection and 2) investigate whether oviposition preference differs between single- and multi-concentration chemical environments. This device may be used to study fundamental and applied biological questions in Drosophila and other egg laying insects. It can also be extended in design to develop sophisticated and dynamic chemical dosing and high-throughput screening platforms in the future that are not easily achievable with the existing oviposition screening techniques.

  17. Microfluidic assessment of swimming media for motility-based sperm selection

    PubMed Central

    Eamer, Lise; Nosrati, Reza; Vollmer, Marion; Zini, Armand; Sinton, David

    2015-01-01

    Selection medium is important in sperm isolation for assisted reproductive technologies. Contrary to the naturally occurring human cervical mucus which has a high viscosity, most current practices for motility based sperm selection use a low viscosity medium. In this study, we used a microfluidic device to assess the effects of high viscosity media made with hyaluronic acid (HA) and methyl cellulose (MC) on bovine and human sperm motility and viability (sperm transferred directly from cryoprotectant). The microfluidic penetration test, viability, and motility were compared for sperm swimming in both HA and MC media with about 20cp viscosity (measured at 20 °C). Our resulted indicate that MC medium resulted in a significantly higher number of viable bovine sperm penetrating the medium as compared to HA. Furthermore, MC resulted in the selection of a sperm subpopulation with a 274% increase in sperm viability in comparison to the raw semen, while HA increased viability by only 133%. In addition to viability, bovine sperm motility parameters were significantly higher in the MC medium as compared with HA. Experiments with human sperm swimming in MC indicate that sperm swim slower and straighter at higher viscosities. In conclusion, the results indicate that in a micro-confined environment representative of the in vivo environment, MC is a preferred high viscosity medium to ensure the highest concentration of motile and viable sperm. PMID:26339314

  18. Systems nanobiology: from quantitative single molecule biophysics to microfluidic-based single cell analysis.

    PubMed

    Martini, Joerg; Hellmich, Wibke; Greif, Dominik; Becker, Anke; Merkle, Thomas; Ros, Robert; Ros, Alexandra; Toensing, Katja; Anselmetti, Dario

    2007-01-01

    Detailed and quantitative information about structure-function relation, concentrations and interaction kinetics of biological molecules and subcellular components is a key prerequisite to understand and model cellular organisation and temporal dynamics. In systems nanobi-ology, cellular processes are quantitatively investigated at the sensitivity level of single molecules and cells. This approach provides direct access to biomolecular information without being statistically ensemble-averaged, their associated distribution functions, and possible subpopulations. Moreover at the single cell level, the interplay of regulated genomic information and proteomic variabilities can be investigated and attributed to functional peculiarities. These requirements necessitate the development of novel and ultrasensitive methods and instruments for single molecule detection, microscopy and spectroscopy for analysis without the need of amplification and preconcentration. In this chapter, we present three methodological applications that demonstrate how quantitative informations can be accessed that are representative for cellular processes or single cell analysis like gene expression regulation, intracellular protein translocation dynamics, and single cell protein fingerprinting. First, the interaction kinetics of transcriptionally regulated DNA-protein interaction can be quantitatively investigated with single molecule force spectroscopy allowing a molecular affinity ranking. Second, intracellular protein dynamics for a transcription regulator migrating form the nucleus to the cytoplasm can be quantitatively monitored by photoactivable GFP and two-photon laser scanning microscopy. And third, a microfluidic-based method for label-free single cell proteomics and fingerprinting and first label-free single cell electropherograms are presented which include the manipulation and steering of single cells in a microfluidic device.

  19. The Evopopbot Chip: Ultra High-throughput Evolutionary Population Bottlenecking using Drop-Based Microfluidics

    NASA Astrophysics Data System (ADS)

    Chang, Connie; Rotem, Assaf; Serohijos, Adrian; Zhang, Huidan; Tao, Ye; Fischer Hesselbrock, Audrey; Thielen, Peter; Mehoke, Thomas; Wolfe, Joshua; Wobus, Christiane; Feldman, Andrew; Shakhnovich, Eugene; Weitz, David

    2014-03-01

    The study of how viruses propagate is important for curing disease and preventing viral outbreaks. In nature, viruses can compete with one another, and the most evolutionary fit virus usually takes over a population. Yet there exist variants in the population that can escape subjected evolutionary pressures and eventually dominate the population. Successful studies of viral epidemics hinges on the ability to access these variants. Here, we present the use of droplet-based microfluidics as a simple method to segregate and propagate a viral population as individual viral lineages, simultaneously performing millions of in vitroevolutionary bottlenecking experiments. We introduce a novel microfluidic device, called the ``Evopopbot Chip'', that allows for simultaneous passaging of millions of evolutionary bottlenecking events by splitting drops containing previous generations of viruses and merging with drops containing new host cells. After several generations of viral replication in the evolution chip, we discover hundreds of new viruses that are able to escape a neutralizing antibody selection pressure compared to bulk passaging.

  20. A novel microfluidics-based method for probing weak protein-protein interactions.

    PubMed

    Tan, Darren Cherng-wen; Wijaya, I Putu Mahendra; Andreasson-Ochsner, Mirjam; Vasina, Elena Nikolaevna; Nallani, Madhavan; Hunziker, Walter; Sinner, Eva-Kathrin

    2012-08-07

    We report the use of a novel microfluidics-based method to detect weak protein-protein interactions between membrane proteins. The tight junction protein, claudin-2, synthesised in vitro using a cell-free expression system in the presence of polymer vesicles as membrane scaffolds, was used as a model membrane protein. Individual claudin-2 molecules interact weakly, although the cumulative effect of these interactions is significant. This effect results in a transient decrease of average vesicle dispersivity and reduction in transport speed of claudin-2-functionalised vesicles. Polymer vesicles functionalised with claudin-2 were perfused through a microfluidic channel and the time taken to traverse a defined distance within the channel was measured. Functionalised vesicles took 1.19 to 1.69 times longer to traverse this distance than unfunctionalised ones. Coating the channel walls with protein A and incubating the vesicles with anti-claudin-2 antibodies prior to perfusion resulted in the functionalised vesicles taking 1.75 to 2.5 times longer to traverse this distance compared to the controls. The data show that our system is able to detect weak as well as strong protein-protein interactions. This system offers researchers a portable, easily operated and customizable platform for the study of weak protein-protein interactions, particularly between membrane proteins.

  1. Glucose microfluidic fuel cell based on silver bimetallic selective catalysts for on-chip applications

    NASA Astrophysics Data System (ADS)

    Cuevas-Muñiz, F. M.; Guerra-Balcázar, M.; Esquivel, J. P.; Sabaté, N.; Arriaga, L. G.; Ledesma-García, J.

    2012-10-01

    A glucose microfluidic fuel cell with outstanding performance at zero flow condition is presented. Polarization tests showed that bimetallic materials based in silver (AuAg/C as anode, PtAg/C as cathode) exhibit tolerance to byproducts and crossover effect. This allowed achieving one of the highest power densities reported for glucose fuel cells, up to a value of 630 μW cm-2 using two separated laminar flows of reactants. Furthermore, the tolerance to crossover effect caused by the selectivity of PtAg/C to oxygen reduction reaction in presence of glucose permitted using a single flow containing a mixture of glucose/oxygen, yielding a performance as high as 270 μW cm-2. Microfluidic fuel cell was further evaluated with a simulated body fluid solution that contained salts commonly present in the human blood plasma, reaching a power of 240 μW cm-2 at zero flow. These results envisage the incorporation of this fuel cell as a portable power source in Lab-on-a-Chip devices without the need of external pumps.

  2. A novel method to fabricate parylene-based flexible microfluidic platforms with commercial adhesive tape

    NASA Astrophysics Data System (ADS)

    Kim, Byung Jun; Lee, Donghee; Lee, Jongho; Yang, Sung

    2015-01-01

    We developed a new method to fabricate parylene-based flexible microfluidic platforms using commercial adhesive tape. Most of the previous methods required the preparation of parylene channels via a parylene-to-parylene bonding, which could only be achieved at high pressure and temperature. Instead, our method exploits the adherent property of commercial tape as a substrate for the parylene peel-off process. Once the parylene thin film is deposited by chemical vapour deposition (CVD) on top of the polydimethylsiloxane (PDMS) replica, prepared by conventional lithography process, an adhesive tape peels off the deposited parylene layer with the micro-scale structures from the PDMS replica. We found that the minimum size of the circle posts successfully fabricated by this process is about 10 μm in diameter and 10 μm in height; the maximum value in aspect ratio is about 2.5. In our experimental investigation, pressure in the parylene channels with different wall thicknesses, was measured to estimate the hydraulic resistance of the channel. Our results are comparable with calculated data, with a normalized deviation smaller than 5%. In addition, the hydraulic resistance of the channels on the curved surface obtained with a similar approach showed an increase when the radius of curvature was reduced. Finally, this contribution shows that our method enables a simple and relatively inexpensive fabrication of flexible microfluidic platforms.

  3. Isolation of Circulating Plasma Cells in Multiple Myeloma Using CD138 Antibody-Based Capture in a Microfluidic Device

    PubMed Central

    Qasaimeh, Mohammad A.; Wu, Yichao C.; Bose, Suman; Menachery, Anoop; Talluri, Srikanth; Gonzalez, Gabriel; Fulciniti, Mariateresa; Karp, Jeffrey M.; Prabhala, Rao H.; Karnik, Rohit

    2017-01-01

    The necessity for bone marrow aspiration and the lack of highly sensitive assays to detect residual disease present challenges for effective management of multiple myeloma (MM), a plasma cell cancer. We show that a microfluidic cell capture based on CD138 antigen, which is highly expressed on plasma cells, permits quantitation of rare circulating plasma cells (CPCs) in blood and subsequent fluorescence-based assays. The microfluidic device is based on a herringbone channel design, and exhibits an estimated cell capture efficiency of ~40–70%, permitting detection of <10 CPCs/mL using 1-mL sample volumes, which is difficult using existing techniques. In bone marrow samples, the microfluidic-based plasma cell counts exhibited excellent correlation with flow cytometry analysis. In peripheral blood samples, the device detected a baseline of 2–5 CD138+ cells/mL in healthy donor blood, with significantly higher numbers in blood samples of MM patients in remission (20–24 CD138+ cells/mL), and yet higher numbers in MM patients exhibiting disease (45–184 CD138+ cells/mL). Analysis of CPCs isolated using the device was consistent with serum immunoglobulin assays that are commonly used in MM diagnostics. These results indicate the potential of CD138-based microfluidic CPC capture as a useful ‘liquid biopsy’ that may complement or partially replace bone marrow aspiration. PMID:28374831

  4. Development of a paper-based carbon nanotube sensing microfluidic device for biological detection.

    PubMed

    Yang, Shih-I; Lei, Kin Fong; Tsai, Shiao-Wen; Hsu, Hsiao-Ting

    2013-01-01

    Carbon nanotube (CNT) has been utilized for the biological detection due to its extremely sensitive to biological molecules. A paper-based CNT sensing microfluidic device has been developed for the detection of protein, i.e., biotin-avidin, binding. We have developed a fabrication method that allows controlled deposition of bundled CNTs with well-defined dimensions to form sensors on paper. Then, polydimethyl siloxane (PDMS) was used to pattern the hydrophobic boundary on paper to form the reaction sites. The proposed fabrication method is based on vacuum filtration process with a metal mask covering on a filter paper for the definition of the dimension of sensor. The length, width, and thickness of the CNT-based sensors are readily controlled by the metal mask and the weight of the CNT powder used during the filtration process, respectively. Homogeneous deposition of CNTs with well-defined dimensions can be achieved. The CNT-based sensor on paper has been demonstrated on the detection of the protein binding. Biotin was first immobilized on the CNT's sidewall and avidin suspended solution was applied to the site. The result of the biotin-avidin binding was measured by the resistance change of the sensor, which is a label-free detection method. It showed the CNT is sensitive to the biological molecules and the proposed paper-based CNT sensing device is a possible candidate for point-of-care biosensors. Thus, electrical bio-assays on paper-based microfluidics can be realized to develop low cost, sensitive, and specific diagnostic devices.

  5. Micro-total analysis system for virus detection: microfluidic pre-concentration coupled to liposome-based detection.

    PubMed

    Connelly, John T; Kondapalli, Sowmya; Skoupi, Marc; Parker, John S L; Kirby, Brian J; Baeumner, Antje J

    2012-01-01

    An integrated microfluidic biosensor is presented that combines sample pre-concentration and liposome-based signal amplification for the detection of enteric viruses present in environmental water samples. This microfluidic approach overcomes the challenges of long assay times of cell culture-based methods and the need to extensively process water samples to eliminate inhibitors for PCR-based methods. Here, viruses are detected using an immunoassay sandwich approach with the reporting antibodies tagged to liposomes. Described is the development of the integrated device for the detection of environmentally relevant viruses using feline calicivirus (FCV) as a model organism for human norovirus. In situ fabricated nanoporous membranes in glass microchannels were used in conjunction with electric fields to achieve pre-concentration of virus-liposome complexes and therefore enhance the antibody-virus binding efficiency. The concentrated complexes were eluted to a detection region downstream where captured liposomes were lysed to release fluorescent dye molecules that were then quantified using image processing. This system was compared to an optimized electrochemical liposome-based microfluidic biosensor without pre-concentration. The limit of detection of FCV of the integrated device was at 1.6 × 10(5) PFU/mL, an order of magnitude lower than that obtained using the microfluidic biosensor without pre-concentration. This significant improvement is a key step toward the goal of using this integrated device as an early screening system for viruses in environmental water samples.

  6. A rapid, straightforward, and print house compatible mass fabrication method for integrating 3D paper-based microfluidics.

    PubMed

    Xiao, Liangpin; Liu, Xianming; Zhong, Runtao; Zhang, Kaiqing; Zhang, Xiaodi; Zhou, Xiaomian; Lin, Bingcheng; Du, Yuguang

    2013-11-01

    Three-dimensional (3D) paper-based microfluidics, which is featured with high performance and speedy determination, promise to carry out multistep sample pretreatment and orderly chemical reaction, which have been used for medical diagnosis, cell culture, environment determination, and so on with broad market prospect. However, there are some drawbacks in the existing fabrication methods for 3D paper-based microfluidics, such as, cumbersome and time-consuming device assembly; expensive and difficult process for manufacture; contamination caused by organic reagents from their fabrication process. Here, we present a simple printing-bookbinding method for mass fabricating 3D paper-based microfluidics. This approach involves two main steps: (i) wax-printing, (ii) bookbinding. We tested the delivery capability, diffusion rate, homogeneity and demonstrated the applicability of the device to chemical analysis by nitrite colorimetric assays. The described method is rapid (<30 s), cheap, easy to manipulate, and compatible with the flat stitching method that is common in a print house, making itself an ideal scheme for large-scale production of 3D paper-based microfluidics.

  7. A high efficiency microfluidic-based photocatalytic microreactor using electrospun nanofibrous TiO2 as a photocatalyst.

    PubMed

    Meng, Zhaoxu; Zhang, Xu; Qin, Jianhua

    2013-06-07

    We present a novel microfluidic-based photocatalytic microreactor by using electrospun nanofibrous TiO2 as a photocatalyst for the first time. The microreactor exhibits not only a simple fabrication process, but also much higher photocatalytic activity than that achieved by a TiO2 film microreactor.

  8. A novel microbead-based microfluidic device for rapid bacterial identification and antibiotic susceptibility testing.

    PubMed

    He, J; Mu, X; Guo, Z; Hao, H; Zhang, C; Zhao, Z; Wang, Q

    2014-12-01

    Effective treatment of infectious diseases depends on the ability to rapidly identify the infecting bacteria and the use of sensitive antibiotics. The currently used identification assays usually take more than 72 h to perform and have a low sensitivity. Herein, we present a microbead-based microfluidic platform that is highly sensitive and rapid for bacterial detection and antibiotic sensitivity testing. The platform includes four units, one of which is used for bacterial identification and the other three are used for susceptibility testing. Our results showed that Escherichia coli O157 at a cell density range of 10(1)-10(5) CFU/μL could be detected within 30 min. Additionally, the effects of three antibiotics on E. coli O157 were evaluated within 4-8 h. Overall, this integrated microbead-based microdevice provides a sensitive, rapid, reliable, and highly effective platform for the identification of bacteria, as well as antibiotic sensitivity testing.

  9. A novel viscoelastic-based ferrofluid for continuous sheathless microfluidic separation of nonmagnetic microparticles.

    PubMed

    Zhang, Jun; Yan, Sheng; Yuan, Dan; Zhao, Qianbin; Tan, Say Hwa; Nguyen, Nam-Trung; Li, Weihua

    2016-10-05

    Separation of microparticles has found broad applications in biomedicine, industry and clinical diagnosis. In a conventional aqueous ferrofluid, separation of microparticles usually employs a sheath flow or two offset magnets to confine particle streams for downstream particle sorting. This complicates the fluid control, device fabrication, and dilutes the particle sample. In this work, we propose and develop a novel viscoelastic ferrofluid by replacing the Newtonian base medium of the conventional ferrofluid with non-Newtonian poly(ethylene oxide) (PEO) aqueous solution. The properties of both viscoelastic 3D focusing and negative magnetophoresis of the viscoelastic ferrofluid were verified and investigated. By employing the both properties in a serial manner, continuous and sheathless separation of nonmagnetic particles based on particle size has been demonstrated. This novel viscoelastic ferrofluid is expected to bring more flexibility and versatility to the design and functionality in microfluidic devices.

  10. Droplet-based microfluidics platform for ultra-high-throughput bioprospecting of cellulolytic microorganisms.

    PubMed

    Najah, Majdi; Calbrix, Raphaël; Mahendra-Wijaya, I Putu; Beneyton, Thomas; Griffiths, Andrew D; Drevelle, Antoine

    2014-12-18

    Discovery of microorganisms producing enzymes that can efficiently hydrolyze cellulosic biomass is of great importance for biofuel production. To date, however, only a miniscule fraction of natural biodiversity has been tested because of the relatively low throughput of screening systems and their limitation to screening only culturable microorganisms. Here, we describe an ultra-high-throughput droplet-based microfluidic system that allowed the screening of over 100,000 cells in less than 20 min. Uncultured bacteria from a wheat stubble field were screened directly by compartmentalization of single bacteria in 20 pl droplets containing a fluorogenic cellobiohydrolase substrate. Sorting of droplets based on cellobiohydrolase activity resulted in a bacterial population with 17- and 7-fold higher cellobiohydrolase and endogluconase activity, respectively, and very different taxonomic diversity than when selected for growth on medium containing starch and carboxymethylcellulose as carbon source.

  11. Integrated Microfluidic System for Size-Based Selection and Trapping of Giant Vesicles.

    PubMed

    Kazayama, Yuki; Teshima, Tetsuhiko; Osaki, Toshihisa; Takeuchi, Shoji; Toyota, Taro

    2016-01-19

    Vesicles composed of phospholipids (liposomes) have attracted interest as artificial cell models and have been widely studied to explore lipid-lipid and lipid-protein interactions. However, the size dispersity of liposomes prepared by conventional methods was a major problem that inhibited their use in high-throughput analyses based on monodisperse liposomes. In this study, we developed an integrative microfluidic device that enables both the size-based selection and trapping of liposomes. This device consists of hydrodynamic selection and trapping channels in series, which made it possible to successfully produce an array of more than 60 monodisperse liposomes from a polydisperse liposome suspension with a narrow size distribution (the coefficient of variation was less than 12%). We successfully observed a size-dependent response of the liposomes to sequential osmotic stimuli, which had not clarified so far, by using this device. Our device will be a powerful tool to facilitate the statistical analysis of liposome dynamics.

  12. Microchannel-based surface-enhanced Raman spectroscopy for integrated microfluidic analysis.

    PubMed

    Lai, Chun-hong; Chen, Li; Chen, Gang; Xu, Yi; Wang, Chun-yan

    2014-01-01

    We have demonstrated a microchannel-based, surface-enhanced Raman spectroscopy (SERS) sensing approach for integrated microfluidic analysis developed using standard micro-fabrication technology. Our approach allows high-sensitivity SERS sensing with a comparatively low-excitation optical power intensity and large cross-sectional microchannel for biological cell analysis. Utilizing a microchannel with a cross section of 100 × 70 μm(2), we achieved a detection limit smaller than 10 nM for rhodamine 6G at an excitation power intensity of 132 W/cm(2), avoiding any possible heating effects on the sample under investigation. There is great potential for further improvement in the sensitivity of this microchannel-based SERS detection.

  13. Optimization of a microfluidic based electromagnetic energy harvester for shoe insoles

    NASA Astrophysics Data System (ADS)

    Rahman, M. M.; Atkin, R.; Kim, H.

    2015-12-01

    This paper reports improved performance of the 4th generation microfluidic based energy harvester by finding global optimization among various geometric parameters, resulting in the increase of power density by 6.89 times. Specifically, the power output was optimized by varying diameters and spans of a coil at different frequencies. To verify the optimization, a custom testing platform was constructed, which mimicked the periodic linear movement caused by a human foot. The final device produced total power of 455.77mW from a volume of 20×3.74×0.75cm3, resulting in a power density of 8.13mW/cm3 that was identified as one of the highest power densities among human-body-induced vibration based energy harvesters.

  14. Integration of Multiple Components in Polystyrene-based Microfluidic Devices Part 2: Cellular Analysis

    PubMed Central

    Anderson, Kari B.; Halpin, Stephen T.; Johnson, Alicia S.; Martin, R. Scott; Spence, Dana M.

    2012-01-01

    In Part II of this series describing the use of polystyrene (PS) devices for microfluidic-based cellular assays, various cellular types and detection strategies are employed to determine three fundamental assays often associated with cells. Specifically, using either integrated electrochemical sensing or optical measurements with a standard multi-well plate reader, cellular uptake, production, or release of important cellular analytes are determined on a PS-based device. One experiment involved the fluorescence measurement of nitric oxide (NO) produced within an endothelial cell line following stimulation with ATP. The result was a four-fold increase in NO production (as compared to a control), with this receptor-based mechanism of NO production verifying the maintenance of cell receptors following immobilization onto the PS substrate. The ability to monitor cellular uptake was also demonstrated by optical determination of Ca2+ into endothelial cells following stimulation with the Ca2+ ionophore A20317. The result was a significant increase (42%) in the calcium uptake in the presence of the ionophore, as compared to a control (17%) (p < 0.05). Finally, the release of catecholamines from a dopaminergic cell line (PC 12 cells) was electrochemically monitored, with the electrodes being embedded into the PS-based device. The PC 12 cells had better adherence on the PS devices, as compared to use of PDMS. Potassium-stimulation resulted in the release of 114 ± 11 µM catecholamines, a significant increase (p < 0.05) over the release from cells that had been exposed to an inhibitor (reserpine, 20 ± 2 µM of catecholamines). The ability to successfully measure multiple analytes, generated in different means from various cells under investigation, suggests that PS may be a useful material for microfluidic device fabrication, especially considering the enhanced cell adhesion to PS, its enhanced rigidity/amenability to automation, and its ability to enable a wider range of

  15. A microfluidic-based cell encapsulation platform to achieve high long-term cell viability in photopolymerized PEGNB hydrogel microspheres.

    PubMed

    Jiang, Zhongliang; Xia, Bingzhao; McBride, Ralph; Oakey, John

    2017-01-07

    Cell encapsulation within photopolymerized polyethylene glycol (PEG)-based hydrogel scaffolds has been demonstrated as a robust strategy for cell delivery, tissue engineering, regenerative medicine, and developing in vitro platforms to study cellular behavior and fate. Strategies to achieve spatial and temporal control over PEG hydrogel mechanical properties, chemical functionalization, and cytocompatibility have advanced considerably in recent years. Recent microfluidic technologies have enabled the miniaturization of PEG hydrogels, thus enabling the fabrication of miniaturized cell-laden vehicles. However, rapid oxygen diffusive transport times on the microscale dramatically inhibit chain growth photopolymerization of polyethylene glycol diacrylate (PEGDA), thus decreasing the viability of cells encapsulated within these microstructures. Another promising PEG-based scaffold material, PEG norbornene (PEGNB), is formed by a step-growth photopolymerization and is not inhibited by oxygen. PEGNB has also been shown to be more cytocompatible than PEGDA and allows for orthogonal addition reactions. The step-growth kinetics, however, are slow and therefore challenging to fully polymerize within droplets flowing through microfluidic devices. Here, we describe a microfluidic-based droplet fabrication platform that generates consistently monodisperse cell-laden water-in-oil emulsions. Microfluidically generated PEGNB droplets are collected and photopolymerized under UV exposure in bulk emulsions. In this work, we compare this microfluidic-based cell encapsulation platform with a vortex-based method on the basis of microgel size, uniformity, post-encapsulation cell viability and long-term cell viability. Several factors that influence post-encapsulation cell viability were identified. Finally, long-term cell viability achieved by this platform was compared to a similar cell encapsulation platform using PEGDA. We show that this PEGNB microencapsulation platform is capable of

  16. Efficient energy based modeling and experimental validation of liquid filling in planar micro-fluidic components and networks.

    PubMed

    Treise, I; Fortner, N; Shapiro, B; Hightower, A

    2005-03-01

    This paper presents a model that describes how liquid flow fills micro-fluidic components and networks. As an alternative to computational fluid dynamic (CFD) simulations, we use a constrained energy minimization approach. This approach is based on two assumptions that hold in many micro-fluidic devices: (i) The length scales are small, and we consider slow filling rates, hence fluid momentum and viscous terms are small compared to surface tension forces, consequently the liquid/gas interfaces can be viewed as a succession of quasi-steady equilibrium configurations. (ii) Any equilibrium configuration corresponds to a surface tension energy minima which is constrained by the device shape and the volume of liquid in the device. The model is developed for planar micro-fluidic devices, is based on a fundamental physical principle, and shows accurate agreement with experimental data. It takes us only a few minutes to evaluate the model for a planar component of any shape using the Surface Evolver software, and this is significantly less then the computer run time required for CFD simulations. Moreover, once a library of component models has been created (which takes less than an hour of computer time) it then takes only seconds to simulate different network architectures with thousands of components. This fast "reconfigure the network and simulate in seconds" capability is essential for the design of truly complex networks that will enable the next generation of passive, micro-fluidic, lab-on-a-chip systems.

  17. A Review on Microfluidic Paper-Based Analytical Devices for Glucose Detection

    PubMed Central

    Liu, Shuopeng; Su, Wenqiong; Ding, Xianting

    2016-01-01

    Glucose, as an essential substance directly involved in metabolic processes, is closely related to the occurrence of various diseases such as glucose metabolism disorders and islet cell carcinoma. Therefore, it is crucial to develop sensitive, accurate, rapid, and cost effective methods for frequent and convenient detections of glucose. Microfluidic Paper-based Analytical Devices (μPADs) not only satisfying the above requirements but also occupying the advantages of portability and minimal sample consumption, have exhibited great potential in the field of glucose detection. This article reviews and summarizes the most recent improvements in glucose detection in two aspects of colorimetric and electrochemical μPADs. The progressive techniques for fabricating channels on μPADs are also emphasized in this article. With the growth of diabetes and other glucose indication diseases in the underdeveloped and developing countries, low-cost and reliably commercial μPADs for glucose detection will be in unprecedentedly demand. PMID:27941634

  18. Highly sensitive microfluidic flow sensor based on aligned piezoelectric poly(vinylidene fluoride-trifluoroethylene) nanofibers

    NASA Astrophysics Data System (ADS)

    Zhang, Lingling; Yu, Xiaolei; You, Sujian; Liu, Huiqin; Zhang, Cancan; Cai, Bo; Xiao, Liang; Liu, Wei; Guo, Shishang; Zhao, Xingzhong

    2015-12-01

    A microfluidic flow sensor based on aligned piezoelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] nanofibers has been developed. The flow sensor is able to linearly measure low flow rates ranging from 13 μl/h to 301 μl/h with a sensitivity of 0.36 mV per 1 μl/h, and the highest voltage difference of 120 mV at a flow rate of 451 μl/h. Moreover, the viscosity of the ethylene glycol aqueous solution ranging from 1 mPa.s to 16.1 mPa.s at 25 °C can be detected in dynamic flow with a stable output. These findings highlight the potential of piezoelectric P(VDF-TrFE) nanofibers in multiferroic applications.

  19. Bio-microfluidic platform for gold nanoprobe based DNA detection--application to Mycobacterium tuberculosis.

    PubMed

    Bernacka-Wojcik, Iwona; Lopes, Paulo; Catarina Vaz, Ana; Veigas, Bruno; Jerzy Wojcik, Pawel; Simões, Pedro; Barata, David; Fortunato, Elvira; Viana Baptista, Pedro; Aguas, Hugo; Martins, Rodrigo

    2013-10-15

    We have projected and fabricated a microfluidic platform for DNA sensing that makes use of an optical colorimetric detection method based on gold nanoparticles. The platform was fabricated using replica moulding technology in PDMS patterned by high-aspect-ratio SU-8 moulds. Biochips of various geometries were tested and evaluated in order to find out the most efficient architecture, and the rational for design, microfabrication and detection performance is presented. The best biochip configuration has been successfully applied to the DNA detection of Mycobacterium tuberculosis using only 3 µl on DNA solution (i.e. 90 ng of target DNA), therefore a 20-fold reduction of reagents volume is obtained when compared with the actual state of the art.

  20. Membrane-Based Emitter for Coupling Microfluidics with Ultrasensitive Nanoelectrospray Ionization-Mass Spectrometry

    SciTech Connect

    Sun, Xuefei; Kelly, Ryan T.; Tang, Keqi; Smith, Richard D.

    2011-06-09

    An integrated poly(dimethylsiloxane) (PDMS) membrane-based microfluidic emitter for high performance nanoelectrospray ionization-mass spectrometry (nanoESI-MS) has been fabricated and evaluated. The ~100-μm-thick emitter was created by cutting a PDMS membrane that protrudes beyond the bulk substrate. The reduced surface area at the emitter enhances the electric field and reduces wetting of the surface by the electrospray solvent. As such, the emitter provides highly stable electrospray at flow rates as low as 10 nL/min, and is compatible with electrospray solvents containing a large organic component (e.g., 90% methanol). This approach enables facile emitter construction, and provides excellent stability, reproducibility and sensitivity, as well as compatibility with multilayer soft lithography.

  1. Membrane-based emitter for coupling microfluidics with ultrasensitive nanoelectrospray ionization-mass spectrometry.

    PubMed

    Sun, Xuefei; Kelly, Ryan T; Tang, Keqi; Smith, Richard D

    2011-07-15

    An integrated poly(dimethylsiloxane) (PDMS) membrane-based microfluidic emitter for high-performance nanoelectrospray ionization mass spectrometry has been fabricated and evaluated. The ∼100-μm-thick emitter was created by cutting a PDMS membrane that protrudes beyond the bulk substrate. The reduced surface area at the emitter enhances the electric field and reduces wetting of the surface by the electrospray solvent. As such, the emitter enables highly stable electrosprays at flow rates as low as 10 nL/min and is compatible with electrospray solvents containing a large organic component (e.g., 90% methanol). This approach enables facile emitter construction and provides excellent stability, reproducibility, and sensitivity as well as compatibility with multilayer soft lithography.

  2. Portable Analyzer Based on Microfluidics/Nanoengineered Electrochemical Sensors for in Situ Characterization of Mixed Wastes

    SciTech Connect

    Wang, Joseph

    2006-06-01

    This research effort aims at developing a portable analytical system for fast, sensitive, and inexpensive, on-site monitoring of toxic transition metals and radionuclides in contaminated DOE Sites. The portable devices will be based on Microscale Total Analytical systems ( -TAS) or ''Lab-on-a-chip'' in combination with electrochemical (stripping-voltammetric) sensors. The resulting microfluidics/electrochemical sensor system would allow testing for toxic metals to be performed more rapidly, inexpensively, and reliably in a field setting. Progress Summary/Accomplishments: This report summarizes the ASU activity over the second year of the project. In accordance to our original objectives our studies have focused on various fundamental and practical aspects of sensing and microchip devices for monitoring metal contaminants. As described in this section, we have made a substantial progress, and introduced effective routes for improving the on-site detection of toxic metals and for interfacing microchips with the real world.

  3. Boron Doped Diamond Paste Electrodes for Microfluidic Paper-Based Analytical Devices.

    PubMed

    Nantaphol, Siriwan; Channon, Robert B; Kondo, Takeshi; Siangproh, Weena; Chailapakul, Orawon; Henry, Charles S

    2017-04-04

    Boron doped diamond (BDD) electrodes have exemplary electrochemical properties; however, widespread use of high-quality BDD has previously been limited by material cost and availability. In the present article, we report the use of a BDD paste electrode (BDDPE) coupled with microfluidic paper-based analytical devices (μPADs) to create a low-cost, high-performance electrochemical sensor. The BDDPEs are easy to prepare from a mixture of BDD powder and mineral oil and can be easily stencil-printed into a variety of electrode geometries. We demonstrate the utility and applicability of BDDPEs through measurements of biological species (norepinephrine and serotonin) and heavy metals (Pb and Cd) using μPADs. Compared to traditional carbon paste electrodes (CPE), BDDPEs exhibit a wider potential window, lower capacitive current, and are able to circumvent the fouling of serotonin. These results demonstrate the capability of BDDPEs as point-of-care sensors when coupled with μPADs.

  4. MEMS-based fabrication and microfluidic analysis of three-dimensional perfusion systems.

    PubMed

    Choi, Yoonsu; Vukasinovic, Jelena; Glezer, Ari; Allen, Mark G

    2008-06-01

    This paper describes fabrication and fluidic characterization of 3D microperfusion systems that could extend the viability of high-density 3D cultures in vitro. High-aspect ratio towers serve as 3D scaffolds to support the cultures and contain injection sites for interstitial delivery of nutrients, drugs, and other reagents. Hollow and solid-top tower arrays with laser ablated side-ports were fabricated using SU-8. Appropriate sizing of fluidic ports improves the control of agent delivery. Microfluidic perfusion can be used to continuously deliver equal amount of nutrients through all ports, or more media can be delivered at some ports than the others, thus allowing spatial control of steady concentration gradients throughout the culture thickness. The induced 3D flow around towers was validated using micro particle image velocimetry. Based on experimental data, the flow rates from the characteristic ports were found to follow the analytical predictions.

  5. Magnetic digital microfluidics - a review.

    PubMed

    Zhang, Yi; Nguyen, Nam-Trung

    2017-03-14

    A digital microfluidic platform manipulates droplets on an open surface. Magnetic digital microfluidics utilizes magnetic forces for actuation and offers unique advantages compared to other digital microfluidic platforms. First, the magnetic particles used in magnetic digital microfluidics have multiple functions. In addition to serving as actuators, they also provide a functional solid substrate for molecule binding, which enables a wide range of applications in molecular diagnostics and immunodiagnostics. Second, magnetic digital microfluidics can be manually operated in a "power-free" manner, which allows for operation in low-resource environments for point-of-care diagnostics where even batteries are considered a luxury item. This review covers research areas related to magnetic digital microfluidics. This paper first summarizes the current development of magnetic digital microfluidics. Various methods of droplet manipulation using magnetic forces are discussed, ranging from conventional magnetic particle-based actuation to the recent development of ferrofluids and magnetic liquid marbles. This paper also discusses several new approaches that use magnetically controlled flexible substrates for droplet manipulation. In addition, we emphasize applications of magnetic digital microfluidics in biosensing and medical diagnostics, and identify the current limitations of magnetic digital microfluidics. We provide a perspective on possible solutions to close these gaps. Finally, the paper discusses the future improvement of magnetic digital microfluidics to explore potential new research directions.

  6. Colorimetric analysis of the decomposition of S-nitrosothiols on paper-based microfluidic devices.

    PubMed

    Ismail, Abdulghani; Araújo, Marillya O; Chagas, Cyro L S; Griveau, Sophie; D'Orlyé, Fanny; Varenne, Anne; Bedioui, Fethi; Coltro, Wendell K T

    2016-10-24

    A disposable microfluidic paper-based analytical device (μPAD) was developed to easily analyse different S-nitrosothiols (RSNOs) through colorimetric measurements. RSNOs are carriers of nitric oxide (NO) that play several physiological and physiopathological roles. The quantification of RSNOs relies on their decomposition using several protocols and the colorimetric detection of the final product, NO or nitrite. μPADs were fabricated by wax printing technology in a geometry containing one central zone for the sample inlet and eight circular detection zones interconnected by microfluidic channels for decomposition and posterior detection of decayed products. Different decomposition protocols including mercuric ions and light (UV, visible, and infrared) were tested on μPADs. For this purpose, a 3D printed holder was coupled with μPADs to easily design a simultaneous decomposition procedure using different light sources. The Griess reagent was added to detect NO and nitrite produced by the different decomposition methods. μPADs were then scanned using a flat board scanner and calibration curves based on color intensity were plotted. The limit of detection (LOD) values achieved for nitrite (used as a reference compound) and S-nitrosoglutathione (GSNO) using mercuric decomposition were 3 and 4 μM, respectively. The LOD reported herein for nitrite is considered among the lowest LODs already reported for this compound using μPADs. The results also show that low-molecular-weight RSNO, namely S-nitrosocysteine, decomposes more easily than high-molecular-weight RSNOs with light. As a proof of concept, RSNOs in human plasma were successfully detected on μPADs. For this purpose, a preliminary treatment step was optimized and the presence of high-molecular-weight (HMW) RSNOs was evidenced in the available plasma samples. The concentrations of HMW-RSNOs and nitrite in the various samples ranged from 5 to 16 μM and from 37 to 58 μM, respectively.

  7. From bioseparation to artificial micro-organs: microfluidic chip based particle manipulation techniques

    NASA Astrophysics Data System (ADS)

    Stelzle, Martin

    2010-02-01

    Microfluidic device technology provides unique physical phenomena which are not available in the macroscopic world. These may be exploited towards a diverse array of applications in biotechnology and biomedicine ranging from bioseparation of particulate samples to the assembly of cells into structures that resemble the smallest functional unit of an organ. In this paper a general overview of chip-based particle manipulation and separation is given. In the state of the art electric, magnetic, optical and gravitational field effects are utilized. Also, mechanical obstacles often in combination with force fields and laminar flow are employed to achieve separation of particles or molecules. In addition, three applications based on dielectrophoretic forces for particle manipulation in microfluidic systems are discussed in more detail. Firstly, a virus assay is demonstrated. There, antibody-loaded microbeads are used to bind virus particles from a sample and subsequently are accumulated to form a pico-liter sized aggregate located at a predefined position in the chip thus enabling highly sensitive fluorescence detection. Secondly, subcellular fractionation of mitochondria from cell homogenate yields pure samples as was demonstrated by Western Blot and 2D PAGE analysis. Robust long-term operation with complex cell homogenate samples while avoiding electrode fouling is achieved by a set of dedicated technical means. Finally, a chip intended for the dielectrophoretic assembly of hepatocytes and endothelial cells into a structure resembling a liver sinusoid is presented. Such "artificial micro organs" are envisioned as substance screening test systems providing significantly higher predictability with respect to the in vivo response towards a substance under test.

  8. Particle-Based Microfluidic Device for Providing High Magnetic Field Gradients

    NASA Technical Reports Server (NTRS)

    Lin, Adam Y. (Inventor); Wong, Tak S. (Inventor)

    2013-01-01

    A microfluidic device for manipulating particles in a fluid has a device body that defines a main channel therein, in which the main channel has an inlet and an outlet. The device body further defines a particulate diverting channel therein, the particulate diverting channel being in fluid connection with the main channel between the inlet and the outlet of the main channel and having a particulate outlet. The microfluidic device also has a plurality of microparticles arranged proximate or in the main channel between the inlet of the main channel and the fluid connection of the particulate diverting channel to the main channel. The plurality of microparticles each comprises a material in a composition thereof having a magnetic susceptibility suitable to cause concentration of magnetic field lines of an applied magnetic field while in operation. A microfluidic particle-manipulation system has a microfluidic particle-manipulation device and a magnet disposed proximate the microfluidic particle-manipulation device.

  9. Detection of ESKAPE Bacterial Pathogens at the Point of Care Using Isothermal DNA-Based Assays in a Portable Degas-Actuated Microfluidic Diagnostic Assay Platform.

    PubMed

    Renner, Lars D; Zan, Jindong; Hu, Linda I; Martinez, Manuel; Resto, Pedro J; Siegel, Adam C; Torres, Clint; Hall, Sara B; Slezak, Tom R; Nguyen, Tuan H; Weibel, Douglas B

    2017-02-15

    An estimated 1.5 billion microbial infections occur globally each year and result in ∼4.6 million deaths. A technology gap associated with commercially available diagnostic tests in remote and underdeveloped regions prevents timely pathogen identification for effective antibiotic chemotherapies for infected patients. The result is a trial-and-error approach that is limited in effectiveness, increases risk for patients while contributing to antimicrobial drug resistance, and reduces the lifetime of antibiotics. This paper addresses this important diagnostic technology gap by describing a low-cost, portable, rapid, and easy-to-use microfluidic cartridge-based system for detecting the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) bacterial pathogens that are most commonly associated with antibiotic resistance. The point-of-care molecular diagnostic system consists of a vacuum-degassed microfluidic cartridge preloaded with lyophilized recombinase polymerase amplification (RPA) assays and a small portable battery-powered electronic incubator/reader. The isothermal RPA assays detect the targeted ESKAPE pathogens with high sensitivity (e.g., a limit of detection of ∼10 nucleic acid molecules) that is comparable to that of current PCR-based assays, and they offer advantages in power consumption, engineering, and robustness, which are three critical elements required for the point-of-care setting.

  10. Integrated Microfluidic Platform for Oral Diagnostics

    PubMed Central

    HERR, AMY E.; HATCH, ANSON V.; GIANNOBILE, WILLIAM V.; THROCKMORTON, DANIEL J.; TRAN, HUU M.; BRENNAN, JAMES S.; SINGH, ANUP K.

    2008-01-01

    While many point-of-care (POC) diagnostic methods have been developed for blood-borne analytes, development of saliva-based POC diagnostics is in its infancy. We have developed a portable microfluidic device for detection of potential biomarkers of periodontal disease in saliva. The device performs rapid microfluidic chip-based immunoassays (<3–10 min) with low sample volume requirements (10 μL) and appreciable sensitivity (nM–pM). Our microfluidic method facilitates hands-free saliva analysis by integrating sample pretreatment (filtering, enrichment, mixing) with electrophoretic immunoassays to quickly measure analyte concentrations in minimally pretreated saliva samples. The microfluidic chip has been integrated with miniaturized electronics, optical elements, such as diode lasers, fluid-handling components, and data acquisition software to develop a portable, self-contained device. The device and methods are being tested by detecting potential biomarkers in saliva samples from patients diagnosed with periodontal disease. Our microchip-based analysis can readily be extended to detection of biomarkers of other diseases, both oral and systemic, in saliva and other oral fluids. PMID:17435142

  11. Deformability based cell margination--a simple microfluidic design for malaria-infected erythrocyte separation.

    PubMed

    Hou, Han Wei; Bhagat, Ali Asgar S; Chong, Alvin Guo Lin; Mao, Pan; Tan, Kevin Shyong Wei; Han, Jongyoon; Lim, Chwee Teck

    2010-10-07

    In blood vessels with luminal diameter less than 300 µm, red blood cells (RBCs) which are smaller in size and more deformable than leukocytes, migrate to the axial centre of the vessel due to flow velocity gradient within the vessels. This phenomenon displaces the leukocytes to the vessel wall and is aptly termed as margination. Here, we demonstrate using microfluidics that stiffer malaria-infected RBCs (iRBCs) behave similar to leukocytes and undergo margination towards the sidewalls. This provides better understanding of the hemodynamic effects of iRBCs in microcirculation and its contribution to pathophysiological outcome relating to cytoadherence to endothelium. In this work, cell margination is mimicked for the separation of iRBCs from whole blood based on their reduced deformability. The malaria infected sample was tested in a simple long straight channel microfluidic device fabricated in polydimethylsiloxane. In this microchannel, cell margination was directed along the channel width with the iRBCs aligning near each sidewall and then subsequently removed using a 3-outlet system, thus achieving separation. Tests were conducted using ring stage and late trophozoite/schizont stage iRBCs. Device performance was quantified by analyzing the distribution of these iRBCs across the microchannel width at the outlet and also conducting flow cytometry analysis. Results indicate recovery of approximately 75% for early stage iRBCs and >90% for late stage iRBCs at the side outlets. The simple and passive system operation makes this technique ideal for on-site iRBCs enrichment in resource-limited settings, and can be applied to other blood cell diseases, e.g. sickle cell anemia and leukemia, characterized by changes in cell stiffness.

  12. Inertia based microfluidic capture and characterisation of circulating tumour cells for the diagnosis of lung cancer

    PubMed Central

    Chudasama, Dimple Y.; Freydina, Daria V.; Freidin, Maxim B.; Leung, Maria; Montero Fernandez, Angeles; Rice, Alexandra; Nicholson, Andrew G.; Karteris, Emmanouil; Anikin, Vladimir

    2016-01-01

    Background Routine clinical application of circulating tumour cells (CTCs) for blood based diagnostics is yet to be established. Despite growing evidence of their clinical utility for diagnosis, prognosis and treatment monitoring, the efficacy of a robust platform and universally accepted diagnostic criteria remain uncertain. We evaluate the diagnostic performance of a microfluidic CTC isolation platform using cytomorphologic criteria in patients undergoing lung cancer surgery. Methods Blood was processed from 51 patients undergoing surgery for known or suspected lung cancer using the ClearBridge ClearCell FX systemTM (ClearBridge Biomedics, Singapore). Captured cells were stained on slides with haematoxylin and eosin (H&E) and independently assessed by two pathologist teams. Diagnostic performance was evaluated against the pathologists reported diagnosis of cancer from surgically obtained specimens. Results Cancer was diagnosed in 43.1% and 54.9% of all cases. In early stage primary lung cancer, between the two reporting teams, a positive diagnosis of CTCs was made for 50% and 66.7% of patients. The agreement between the reporting teams was 80.4%, corresponding to a kappa-statistic of 0.61±0.11 (P<0.001), indicating substantial agreement. Sensitivity levels for the two teams were calculated as 59% (95% CI, 41–76%) and 41% (95% CI, 24–59%), with a specificity of 53% for both. Conclusions The performance of the tested microfluidic antibody independent device to capture CTCs using standard cytomorphological criteria provides the potential of a diagnostic blood test for lung cancer. PMID:28149842

  13. Assessment of Carbon- and Metal-Based Nanoparticle DNA Damage with Microfluidic Electrophoretic Separation Technology.

    PubMed

    Schrand, Amanda M; Powell, Thomas; Robertson, Tiffany; Hussain, Saber M

    2015-02-01

    In this study, we examined the feasibility of extracting DNA from whole cell lysates exposed to nanoparticles using two different methodologies for evaluation of fragmentation with microfluidic electrophoretic separation. Human lung macrophages were exposed to five different carbon- and metal-based nanoparticles at two different time points (2 h, 24 h) and two different doses (5 µg/ml, 100 µg/ml). The primary difference in the banding patterns after 2 h of nanoparticle exposure is more DNA fragmentation at the higher NP concentration when examining cells exposed to nanoparticles of the same composition. However, higher doses of carbon and silver nanoparticles at both short and long dosing periods can contribute to erroneous or incomplete data with this technique. Also comparing DNA isolation methodologies, we recommend the centrifugation extraction technique, which provides more consistent banding patterns in the control samples compared to the spooling technique. Here we demonstrate that multi-walled carbon nanotubes, 15 nm silver nanoparticles and the positive control cadmium oxide cause similar DNA fragmentation at the short time point of 2 h with the centrifugation extraction technique. Therefore, the results of these studies contribute to elucidating the relationship between nanoparticle physicochemical properties and DNA fragmentation results while providing the pros and cons of altering the DNA isolation methodology. Overall, this technique provides a high throughput way to analyze subcellular alterations in DNA profiles of cells exposed to nanomaterials to aid in understanding the consequences of exposure and mechanistic effects. Future studies in microfluidic electrophoretic separation technologies should be investigated to determine the utility of protein or other assays applicable to cellular systems exposed to nanoparticles.

  14. Modeling RedOx-based magnetohydrodynamics in three-dimensional microfluidic channels

    NASA Astrophysics Data System (ADS)

    Kabbani, Hussameddine; Wang, Aihua; Luo, Xiaobing; Qian, Shizhi

    2007-08-01

    RedOx-based magnetohydrodynamic (MHD) flows in three-dimensional microfluidic channels are investigated theoretically with a coupled mathematical model consisting of the Nernst-Planck equations for the concentrations of ionic species, the local electroneutrality condition for the electric potential, and the Navier-Stokes equations for the flow field. A potential difference is externally applied across two planar electrodes positioned along the opposing walls of a microchannel that is filled with a dilute RedOx electrolyte solution, and a Faradaic current transmitted through the solution results. The entire device is positioned under a magnetic field which can be provided by either a permanent magnet or an electromagnet. The interaction between the current density and the magnetic field induces Lorentz forces, which can be used to pump and/or stir fluids for microfluidic applications. The induced currents and flow rates in three-dimensional (3D) planar channels obtained from the full 3D model are compared with the experimental data obtained from the literature and those obtained from our previous two-dimensional mathematical model. A closed form approximation for the average velocity (flow rate) in 3D planar microchannels is derived and validated by comparing its predictions with the results obtained from the full 3D model and the experimental data obtained from the literature. The closed form approximation can be used to optimize the dimensions of the channel and to determine the magnitudes and polarities of the prescribed currents in MHD networks so as to achieve the desired flow patterns and flow rates.

  15. A microfluidic-based electrochemical biochip for label-free DNA hybridization analysis.

    PubMed

    Ben-Yoav, Hadar; Dykstra, Peter H; Gordonov, Tanya; Bentley, William E; Ghodssi, Reza

    2014-09-10

    Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration of pre-processing steps. Utilizing these devices towards the analysis of DNA hybridization events is important because it offers a technology for real time assessment of biomarkers at the point-of-care for various diseases. However, when the device footprint decreases the dominance of various physical phenomena increases. These phenomena influence the fabrication precision and operation reliability of the device. Therefore, there is a great need to accurately fabricate and operate these devices in a reproducible manner in order to improve the overall performance. Here, we describe the protocols and the methods used for the fabrication and the operation of a microfluidic-based electrochemical biochip for accurate analysis of DNA hybridization events. The biochip is composed of two parts: a microfluidic chip with three parallel micro-channels made of polydimethylsiloxane (PDMS), and a 3 x 3 arrayed electrochemical micro-chip. The DNA hybridization events are detected using electrochemical impedance spectroscopy (EIS) analysis. The EIS analysis enables monitoring variations of the properties of the electrochemical system that are dominant at these length scales. With the ability to monitor changes of both charge transfer and diffusional resistance with the biosensor, we demonstrate the selectivity to complementary ssDNA targets, a calculated detection limit of 3.8 nM, and a 13% cross-reactivity with other non-complementary ssDNA following 20 min of incubation. This methodology can improve the performance of miniaturized devices by elucidating on the behavior of diffusion at the micro-scale regime and by enabling the study of DNA hybridization events.

  16. A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis

    PubMed Central

    Ben-Yoav, Hadar; Dykstra, Peter H.; Gordonov, Tanya; Bentley, William E.; Ghodssi, Reza

    2014-01-01

    Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration of pre-processing steps. Utilizing these devices towards the analysis of DNA hybridization events is important because it offers a technology for real time assessment of biomarkers at the point-of-care for various diseases. However, when the device footprint decreases the dominance of various physical phenomena increases. These phenomena influence the fabrication precision and operation reliability of the device. Therefore, there is a great need to accurately fabricate and operate these devices in a reproducible manner in order to improve the overall performance. Here, we describe the protocols and the methods used for the fabrication and the operation of a microfluidic-based electrochemical biochip for accurate analysis of DNA hybridization events. The biochip is composed of two parts: a microfluidic chip with three parallel micro-channels made of polydimethylsiloxane (PDMS), and a 3 x 3 arrayed electrochemical micro-chip. The DNA hybridization events are detected using electrochemical impedance spectroscopy (EIS) analysis. The EIS analysis enables monitoring variations of the properties of the electrochemical system that are dominant at these length scales. With the ability to monitor changes of both charge transfer and diffusional resistance with the biosensor, we demonstrate the selectivity to complementary ssDNA targets, a calculated detection limit of 3.8 nM, and a 13% cross-reactivity with other non-complementary ssDNA following 20 min of incubation. This methodology can improve the performance of miniaturized devices by elucidating on the behavior of diffusion at the micro-scale regime and by enabling the study of DNA hybridization events. PMID:25285529

  17. Monolithic cell counter based on 3D hydrodynamic focusing in microfluidic channels

    NASA Astrophysics Data System (ADS)

    Paiè, Petra; Bragheri, Francesca; Osellame, Roberto

    2014-03-01

    Hydrodynamic focusing is a powerful technique frequently used in microfluidics that presents a wide range of applications since it allows focusing the sample flowing in the device to a narrow region in the center of the microchannel. In fact thanks to the laminarity of the fluxes in microchannels it is possible to confine the sample solution with a low flow rate by using a sheath flow with a higher flow rate. This in turn allows the flowing of one sample element at a time in the detection region, thus enabling analysis on single particles. Femtosecond laser micromachining is ideally suited to fabricate device integrating full hydrodynamic focusing functionalities thanks to the intrinsic 3D nature of this technique, especially if compared to expensive and complicated lithographic multi-step fabrication processes. Furthermore, because of the possibility to fabricate optical waveguides with the same technology, it is possible to obtain compact optofluidic devices to perform optical analysis of the sample even at the single cell level, as is the case for optical cell stretchers and sorters. In this work we show the fabrication and the fluidic characterization of extremely compact devices having only two inlets for 2D (both in vertical and horizontal planes) as well as full 3D symmetric hydrodynamic focusing. In addition we prove one of the possible application of the hydrodynamic focusing module, by fabricating and validating (both with polystyrene beads and erythrocytes) a monolithic cell counter obtained by integrating optical waveguides in the 3D hydrodynamic focusing device.

  18. Microfluidic paper-based analytical devices fabricated by low-cost photolithography and embossing of Parafilm®.

    PubMed

    Yu, Ling; Shi, Zhuan Zhuan

    2015-04-07

    Microfluidic paper-based analytical devices (μPADs) attract tremendous attention as an economical tool for in-field diagnosis, food safety and environmental monitoring. We innovatively fabricated 2D and 3D μPADs by photolithography-patterning microchannels on a Parafilm® and subsequently embossing them to paper. This truly low-cost, wax printer and cutter plotter independent approach offers the opportunity for researchers from resource-limited laboratories to work on paper-based analytical devices.

  19. Integration of Multiple Components in Polystyrene-based Microfluidic Devices Part 1: Fabrication and Characterization

    PubMed Central

    Johnson, Alicia S.; Anderson, Kari B.; Halpin, Stephen T.; Kirkpatrick, Douglas C.; Spence, Dana M.; Martin, R. Scott

    2012-01-01

    In Part I of a two-part series, we describe a simple, and inexpensive approach to fabricate polystyrene devices that is based upon melting polystyrene (from either a Petri dish or powder form) against PDMS molds or around electrode materials. The ability to incorporate microchannels in polystyrene and integrate the resulting device with standard laboratory equipment such as an optical plate reader for analyte readout and micropipettors for fluid propulsion is first described. A simple approach for sample and reagent delivery to the device channels using a standard, multi-channel micropipette and a PDMS-based injection block is detailed. Integration of the microfluidic device with these off-chip functions (sample delivery and readout) enables high throughput screens and analyses. An approach to fabricate polystyrene-based devices with embedded electrodes is also demonstrated, thereby enabling the integration of microchip electrophoresis with electrochemical detection through the use of a palladium electrode (for a decoupler) and carbon-fiber bundle (for detection). The device was sealed against a PDMS-based microchannel and used for the electrophoretic separation and amperometric detection of dopamine, epinephrine, catechol, and 3,4-dihydroxyphenylacetic acid. Finally, these devices were compared against PDMS-based microchips in terms of their optical transparency and absorption of an anti-platelet drug, clopidogrel. Part I of this series lays the foundation for Part II, where these devices were utilized for various on-chip cellular analysis. PMID:23120747

  20. MEMS in microfluidic channels.

    SciTech Connect

    Ashby, Carol Iris Hill; Okandan, Murat; Michalske, Terry A.; Sounart, Thomas L.; Matzke, Carolyn M.

    2004-03-01

    Microelectromechanical systems (MEMS) comprise a new class of devices that include various forms of sensors and actuators. Recent studies have shown that microscale cantilever structures are able to detect a wide range of chemicals, biomolecules or even single bacterial cells. In this approach, cantilever deflection replaces optical fluorescence detection thereby eliminating complex chemical tagging steps that are difficult to achieve with chip-based architectures. A key challenge to utilizing this new detection scheme is the incorporation of functionalized MEMS structures within complex microfluidic channel architectures. The ability to accomplish this integration is currently limited by the processing approaches used to seal lids on pre-etched microfluidic channels. This report describes Sandia's first construction of MEMS instrumented microfluidic chips, which were fabricated by combining our leading capabilities in MEMS processing with our low-temperature photolithographic method for fabricating microfluidic channels. We have explored in-situ cantilevers and other similar passive MEMS devices as a new approach to directly sense fluid transport, and have successfully monitored local flow rates and viscosities within microfluidic channels. Actuated MEMS structures have also been incorporated into microfluidic channels, and the electrical requirements for actuation in liquids have been quantified with an elegant theory. Electrostatic actuation in water has been accomplished, and a novel technique for monitoring local electrical conductivities has been invented.

  1. Aptamer-based microfluidic device for enrichment, sorting, and detection of multiple cancer cells.

    PubMed

    Xu, Ye; Phillips, Joseph A; Yan, Jilin; Li, Qingge; Fan, Z Hugh; Tan, Weihong

    2009-09-01

    The ability to diagnose cancer based on the detection of rare cancer cells in blood or other bodily fluids is a significant challenge. To address this challenge, we have developed a microfluidic device that can simultaneously sort, enrich, and then detect multiple types of cancer cells from a complex sample. The device, which is made from poly(dimethylsiloxane) (PDMS), implements cell-affinity chromatography based on the selective cell-capture of immobilized DNA-aptamers and yields a 135-fold enrichment of rare cells in a single run. This enrichment is achieved because the height of the channel is on the order of a cell diameter. The sorted cells grow at the comparable rate as cultured cells and are 96% pure based on flow cytometry determination. Thus, by using our aptamer based device, cell capture is achieved simply and inexpensively, with no sample pretreatment before cell analysis. Enrichment and detection of multiple rare cancer cells can be used to detect cancers at the early stages, diagnose metastatic relapse, stratify patients for therapeutic purposes, monitor response to drugs and therapies, track tumor progression, and gain a deeper understanding of the biology of circulating tumor cells (CTCs).

  2. Distance-based microfluidic quantitative detection methods for point-of-care testing.

    PubMed

    Tian, Tian; Li, Jiuxing; Song, Yanling; Zhou, Leiji; Zhu, Zhi; Yang, Chaoyong James

    2016-04-07

    Equipment-free devices with quantitative readout are of great significance to point-of-care testing (POCT), which provides real-time readout to users and is especially important in low-resource settings. Among various equipment-free approaches, distance-based visual quantitative detection methods rely on reading the visual signal length for corresponding target concentrations, thus eliminating the need for sophisticated instruments. The distance-based methods are low-cost, user-friendly and can be integrated into portable analytical devices. Moreover, such methods enable quantitative detection of various targets by the naked eye. In this review, we first introduce the concept and history of distance-based visual quantitative detection methods. Then, we summarize the main methods for translation of molecular signals to distance-based readout and discuss different microfluidic platforms (glass, PDMS, paper and thread) in terms of applications in biomedical diagnostics, food safety monitoring, and environmental analysis. Finally, the potential and future perspectives are discussed.

  3. Optical biosensor system with integrated microfluidic sample preparation and TIRF based detection

    NASA Astrophysics Data System (ADS)

    Gilli, Eduard; Scheicher, Sylvia R.; Suppan, Michael; Pichler, Heinz; Rumpler, Markus; Satzinger, Valentin; Palfinger, Christian; Reil, Frank; Hajnsek, Martin; Köstler, Stefan

    2013-05-01

    There is a steadily growing demand for miniaturized bioanalytical devices allowing for on-site or point-of-care detection of biomolecules or pathogens in applications like diagnostics, food testing, or environmental monitoring. These, so called labs-on-a-chip or micro-total analysis systems (μ-TAS) should ideally enable convenient sample-in - result-out type operation. Therefore, the entire process from sample preparation, metering, reagent incubation, etc. to detection should be performed on a single disposable device (on-chip). In the early days such devices were mainly fabricated using glass or silicon substrates and adapting established fabrication technologies from the electronics and semiconductor industry. More recently, the development focuses on the use of thermoplastic polymers as they allow for low-cost high volume fabrication of disposables. One of the most promising materials for the development of plastic based lab-on-achip systems are cyclic olefin polymers and copolymers (COP/COC) due to their excellent optical properties (high transparency and low autofluorescence) and ease of processing. We present a bioanalytical system for whole blood samples comprising a disposable plastic chip based on TIRF (total internal reflection fluorescence) optical detection. The chips were fabricated by compression moulding of COP and microfluidic channels were structured by hot embossing. These microfluidic structures integrate several sample pretreatment steps. These are the separation of erythrocytes, metering of sample volume using passive valves, and reagent incubation for competitive bioassays. The surface of the following optical detection zone is functionalized with specific capture probes in an array format. The plastic chips comprise dedicated structures for simple and effective coupling of excitation light from low-cost laser diodes. This enables TIRF excitation of fluorescently labeled probes selectively bound to detection spots at the microchannel surface

  4. IFSA: a microfluidic chip-platform for frit-based immunoassay protocols

    NASA Astrophysics Data System (ADS)

    Hlawatsch, Nadine; Bangert, Michael; Miethe, Peter; Becker, Holger; Gärtner, Claudia

    2013-03-01

    Point-of-care diagnostics (POC) is one of the key application fields for lab-on-a-chip devices. While in recent years much of the work has concentrated on integrating complex molecular diagnostic assays onto a microfluidic device, there is a need to also put comparatively simple immunoassay-type protocols on a microfluidic platform. In this paper, we present the development of a microfluidic cartridge using an immunofiltration approach. In this method, the sandwich immunoassay takes place in a porous frit on which the antibodies have immobilized. The device is designed to be able to handle three samples in parallel and up to four analytical targets per sample. In order to meet the critical cost targets for the diagnostic market, the microfluidic chip has been designed and manufactured using high-volume manufacturing technologies in mind. Validation experiments show comparable sensitivities in comparison with conventional immunofiltration kits.

  5. Recent Progress of Microfluidics in Translational Applications

    PubMed Central

    Liu, Zongbin; Han, Xin

    2016-01-01

    Microfluidics, featuring microfabricated structures, is a technology for manipulating fluids at the micrometer scale. The small dimension and flexibility of microfluidic systems are ideal for mimicking molecular and cellular microenvironment, and show great potential in translational research and development. Here, the recent progress of microfluidics in biological and biomedical applications, including molecular analysis, cellular analysis, and chip-based material delivery and biomimetic design is presented. The potential future developments in the translational microfluidics field are also discussed. PMID:27091777

  6. Recent Progress of Microfluidics in Translational Applications.

    PubMed

    Liu, Zongbin; Han, Xin; Qin, Lidong

    2016-04-20

    Microfluidics, featuring microfabricated structures, is a technology for manipulating fluids at the micrometer scale. The small dimension and flexibility of microfluidic systems are ideal for mimicking molecular and cellular microenvironment, and show great potential in translational research and development. Here, the recent progress of microfluidics in biological and biomedical applications, including molecular analysis, cellular analysis, and chip-based material delivery and biomimetic design is presented. The potential future developments in the translational microfluidics field are also discussed.

  7. Rapid, targeted and culture-free viral infectivity assay in drop-based microfluidics.

    PubMed

    Tao, Ye; Rotem, Assaf; Zhang, Huidan; Chang, Connie B; Basu, Anindita; Kolawole, Abimbola O; Koehler, Stephan A; Ren, Yukun; Lin, Jeffrey S; Pipas, James M; Feldman, Andrew B; Wobus, Christiane E; Weitz, David A

    2015-10-07

    A key viral property is infectivity, and its accurate measurement is crucial for the understanding of viral evolution, disease and treatment. Currently viral infectivity is measured using plaque assays, which involve prolonged culturing of host cells, and whose measurement is unable to differentiate between specific strains and is prone to low number fluctuation. We developed a rapid, targeted and culture-free infectivity assay using high-throughput drop-based microfluidics. Single infectious viruses are incubated in a large number of picoliter drops with host cells for one viral replication cycle followed by in-drop gene-specific amplification to detect infection events. Using murine noroviruses (MNV) as a model system, we measure their infectivity and determine the efficacy of a neutralizing antibody for different variants of MNV. Our results are comparable to traditional plaque-based assays and plaque reduction neutralization tests. However, the fast, low-cost, highly accurate genomic-based assay promises to be a superior method for drug screening and isolation of resistant viral strains. Moreover our technique can be adapted to measuring the infectivity of other pathogens, such as bacteria and fungi.

  8. Determination of Nitrite in Saliva using Microfluidic Paper-Based Analytical Devices

    PubMed Central

    Bhakta, Samir A.; Borba, Rubiane; Taba, Mario; Garcia, Carlos D.; Carrilho, Emanuel

    2014-01-01

    Point-of-care platforms can provide fast responses, decrease the overall cost of the treatment, allow for in-home determinations with or without a trained specialist, and improve the success of the treatment. This is especially true for microfluidic paper-based analytical devices (μPAD), which can enable the development of highly efficient and versatile analytical tools with applications in a variety of biomedical fields. The objective of this work was the development of μPADs to identify and quantify levels of nitrite in saliva, which has been proposed as a potential marker of periodontitis. The devices were fabricated by wax printing and allowed the detection of nitrite by a colorimetric reaction based on a modified version of the Griess reaction. The presented modifications, along with the implementation of a paper-based platform, address many of the common drawbacks (color development, stability, etc.) associated with the Griess reaction and are supported by results related to the design, characterization, and application of the proposed devices. Under the optimized conditions, the proposed devices enable the determination of nitrite in the 10 to 1000 μmol L−1 range with a limit of detection of 10 μmol L−1 and a sensitivity of 47.5 AU [log (μmol L−1)]−1. In order to demonstrate the potential impact of this technology in the healthcare industry, the devices were applied to the analysis of a series of real samples, covering the relevant clinical range. PMID:24418141

  9. Determination of nitrite in saliva using microfluidic paper-based analytical devices.

    PubMed

    Bhakta, Samir A; Borba, Rubiane; Taba, Mario; Garcia, Carlos D; Carrilho, Emanuel

    2014-01-27

    Point-of-care platforms can provide fast responses, decrease the overall cost of the treatment, allow for in-home determinations with or without a trained specialist, and improve the success of the treatment. This is especially true for microfluidic paper-based analytical devices (μPAD), which can enable the development of highly efficient and versatile analytical tools with applications in a variety of biomedical fields. The objective of this work was the development of μPADs to identify and quantify levels of nitrite in saliva, which has been proposed as a potential marker of periodontitis. The devices were fabricated by wax printing and allowed the detection of nitrite by a colorimetric reaction based on a modified version of the Griess reaction. The presented modifications, along with the implementation of a paper-based platform, address many of the common drawbacks (color development, stability, etc.) associated with the Griess reaction and are supported by results related to the design, characterization, and application of the proposed devices. Under the optimized conditions, the proposed devices enable the determination of nitrite in the 10-1000 μmol L(-1) range with a limit of detection of 10 μmol L(-1) and a sensitivity of 47.5 AU [log (μmol L(-1))](-1). In order to demonstrate the potential impact of this technology in the healthcare industry, the devices were applied to the analysis of a series of real samples, covering the relevant clinical range.

  10. Combined microfluidic-optical DNA analysis with single-base-pair sizing capability

    PubMed Central

    Pollnau, Markus; Hammer, Manfred; Dongre, Chaitanya; Hoekstra, Hugo J. W. M.

    2016-01-01

    DNA sequencing by microchip capillary electrophoresis (CE) enables cheap, high-speed analysis of low reagent volumes. One of its potential applications is the identification of genomic deletions or insertions associated with genetic illnesses. Detecting single base-pair insertions or deletions from DNA fragments in the diagnostically relevant size range of 150−1000 base-pairs requires a variance of σ2 < 10−3. In a microfluidic chip post-processed by femtosecond-laser writing of an optical waveguide we CE-separated 12 blue-labeled and 23 red-labeled DNA fragments in size. Each set was excited by either of two lasers power-modulated at different frequencies, their fluorescence detected by a photomultiplier, and blue and red signals distinguished by Fourier analysis. We tested different calibration strategies. Choice of the fluorescent label as well as the applied fit function strongly influence the obtained variance, whereas fluctuations between two consecutive experiments are less detrimental in a laboratory environment. We demonstrate a variance of σ2 ≈4 × 10−4, lower than required for the detection of single base-pair insertion or deletion in an optofluidic chip. PMID:28018736

  11. Qualification of a microfluidics-based electrophoretic method for impurity testing of monoclonal antibodies.

    PubMed

    Antes, Bernhard; Oberkleiner, Philipp; Nechansky, Andreas; Szolar, Oliver H J

    2010-02-05

    In this work, we present a comprehensive evaluation of the Agilent Bioanalyzer, a microfluidics-based electrophoretic device that was used for impurity testing of a monoclonal antibody (mAb). We compared the system to SDS-PAGE, both operated under non-reducing conditions and found a significant improvement of accuracy for the Bioanalyzer. In addition, the latter exhibited a larger assay range and lower limit of quantitation (LOQ) based on a predefined total error limit of +/-30%. However, during method qualification applying a three-factor nested design with two operators performing duplicate measurements per day, each on 4 different days, we observed unpredictable recurring quantitative outliers using the chip-based system. In-depth analysis on multiple runs with various chip lots confirmed the above finding and indicated that most likely on-chip dye labeling and/or post-column background fluorescence elimination are not compatible with the large size of the intact antibody as similar findings were observed for myosin used as upper marker for time correction. Interestingly, after reducing the intact antibody into light and heavy chain, we resolved the outlier issue. Eventually, requalification of the micro-fabricated analytical device under reducing conditions revealed only 1 out of 32 quality control samples (QCs) exceeding the +/-30% total error limits.

  12. Punch card programmable microfluidics.

    PubMed

    Korir, George; Prakash, Manu

    2015-01-01

    Small volume fluid handling in single and multiphase microfluidics provides a promising strategy for efficient bio-chemical assays, low-cost point-of-care diagnostics and new approaches to scientific discoveries. However multiple barriers exist towards low-cost field deployment of programmable microfluidics. Incorporating multiple pumps, mixers and discrete valve based control of nanoliter fluids and droplets in an integrated, programmable manner without additional required external components has remained elusive. Combining the idea of punch card programming with arbitrary fluid control, here we describe a self-contained, hand-crank powered, multiplex and robust programmable microfluidic platform. A paper tape encodes information as a series of punched holes. A mechanical reader/actuator reads these paper tapes and correspondingly executes operations onto a microfluidic chip coupled to the platform in a plug-and-play fashion. Enabled by the complexity of codes that can be represented by a series of holes in punched paper tapes, we demonstrate independent control of 15 on-chip pumps with enhanced mixing, normally-closed valves and a novel on-demand impact-based droplet generator. We demonstrate robustness of operation by encoding a string of characters representing the word "PUNCHCARD MICROFLUIDICS" using the droplet generator. Multiplexing is demonstrated by implementing an example colorimetric water quality assays for pH, ammonia, nitrite and nitrate content in different water samples. With its portable and robust design, low cost and ease-of-use, we envision punch card programmable microfluidics will bring complex control of microfluidic chips into field-based applications in low-resource settings and in the hands of children around the world.

  13. Mass spectrometry-based monitoring of millisecond protein–ligand binding dynamics using an automated microfluidic platform

    SciTech Connect

    Cong, Yongzheng; Katipamula, Shanta; Trader, Cameron D.; Orton, Daniel J.; Geng, Tao; Baker, Erin S.; Kelly, Ryan T.

    2016-01-01

    Characterizing protein-ligand binding dynamics is crucial for understanding protein function and developing new therapeutic agents. We have developed a novel microfluidic platform that features rapid mixing of protein and ligand solutions, variable incubation times, and on-chip electrospray ionization to perform label-free, solution-based monitoring of protein-ligand binding dynamics. This platform offers many advantages including automated processing, rapid mixing, and low sample consumption.

  14. Human genomic DNA isolation from whole blood using a simple microfluidic system with silica- and polymer-based stationary phases.

    PubMed

    Günal, Gülçin; Kip, Çiğdem; Öğüt, Sevim Eda; Usta, Duygu Deniz; Şenlik, Erhan; Kibar, Güneş; Tuncel, Ali

    2017-05-01

    Monodisperse-porous silica microspheres 5.1μm in size with a bimodal pore-size distribution (including both mesoporous and macroporous compartments) were obtained using a newly developed staged-shape templated hydrolysis and condensation protocol. Synthesized silica microspheres and monodisperse-porous polymer-based microspheres with different functionalities, synthesized by staged-shape template polymerization, were comparatively tested as sorbents for human genomic DNA (hgDNA) isolation in a microfluidic system. Microcolumns with a permeability range of 1.8-8.5×10(-13)m(2) were fabricated by the slurry-packing of silica- or polymer-based microspheres. The monodisperse-porous silica microspheres showed the best performance in hgDNA isolation in an aqueous buffer medium; >2500ng of hgDNA was recovered with an isolation yield of about 50%, using an hgDNA feed concentration of 100ng/μL. Monodisperse-porous silica microspheres were also evaluated as a sorbent for genomic DNA isolation from human whole blood in the microfluidic system; 14ng of hgDNA was obtained from 10μL of whole blood lysate with an isolation yield of 64%. Based on these results, we conclude that monodisperse-porous silica microspheres with a bimodal pore size distribution are a promising sorbent for the isolation of hgDNA in larger amounts and with higher yields compared to the sorbents previously tried in similar microfluidic systems.

  15. Low-cost, high-throughput fabrication of cloth-based microfluidic devices using a photolithographical patterning technique.

    PubMed

    Wu, Peijing; Zhang, Chunsun

    2015-03-21

    In this work, we first report a facile, low-cost and high-throughput method for photolithographical fabrication of microfluidic cloth-based analytical devices (μCADs) by simply using a cotton cloth as a substrate material and employing an inexpensive hydrophobic photoresist laboratory-formulated from commercially available reagents, which allows patterning of reproducible hydrophilic-hydrophobic features in the cloth with well-defined and uniform boundaries. Firstly, we evaluated the wicking properties of cotton cloths by testing the wicking rate in the cloth channel, in combination with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. It is demonstrated that the wicking properties of the cloth microfluidic channel can be improved by soaking the cloth substrate in 20 wt% NaOH solution and by washing the cloth-based microfluidic patterns with 3 wt% SDS solution. Next, we studied the minimum dimensions achievable for the width of the hydrophobic barriers and hydrophilic channels. The results indicate that the smallest width for a desired hydrophobic barrier is designed to be 100 μm and that for a desired hydrophilic channel is designed to be 500 μm. Finally, the high-throughput μCADs prepared using the developed fabrication technique were demonstrated for colorimetric assays of glucose and protein in artificial urine samples. It has been shown that the photolithographically patterned μCADs have potential for a simple, quantitative colorimetric urine test. The combination of cheap cloth and inexpensive high-throughput photolithography enables the development of new types of low-cost cloth-based microfluidic devices, such as "microzone plates" and "gate arrays", which provide new methods to perform biochemical assays or control fluid flow.

  16. Microfluidic-based G-quadruplex ligand displacement assay for alkaloid anticancer drug screening.

    PubMed

    Shen, Haihui; Zhang, Bo; Xu, Huiyan; Sun, Yue; Wu, Qiwang; Shen, Hong; Liu, Yingchun

    2017-02-05

    Some natural heterocyclic alkaloids containing planar group show potential to complex with specific promoter region of protooncogene for stabilizing the G-quadruplex (G4) structure which nowadays promises to be a target in anticancer drug design. However, in view of the polymorphic characteristics and structural complexity of heterocyclic alkaloids, it is desirable to develop high-throughput and low-consumption approach for anticancer drug screening. In this paper, an intensive study on alkaloid ligand/G4 DNA interaction has been conducted, demonstrating that the end-stacking interaction is the favorable binding mode between the oncogene-related Pu22 G4 DNA and the heterocyclic alkaloid ligand. Based on structural feasibility and energy minimization, a ligand displacement assay for screening alkaloid ligand in stabilizing the oncogene target G4 has been developed, which also helps to facilitate the assessment of drug specificity. Coupled with microfluidic-based DNAzyme-catalytic chemiluminescence detection, the approach showed the advantages of high sensitivity, high throughput with low sample and reagent consumptions.

  17. Droplet-based lipid bilayer system integrated with microfluidic channels for solution exchange.

    PubMed

    Tsuji, Yutaro; Kawano, Ryuji; Osaki, Toshihisa; Kamiya, Koki; Miki, Norihisa; Takeuchi, Shoji

    2013-04-21

    This paper proposes a solution exchange of a droplet-based lipid bilayer system, in which the inner solution of a droplet is replaced for the purpose of efficient ion channel analyses. In our previous report, we successfully recorded the channel conductance of alpha-hemolysin in a bilayer lipid membrane using a droplet contact method that can create a spontaneous lipid bilayer at the interface of contacting droplets; this method is widely used as highly efficient method for preparing planar lipid membranes. When only pipetting droplets of the solution, this method is highly efficient for preparing lipid membranes. However, the drawback of droplet-based systems is their inability to exchange the solution within the droplets. To study the effect of inhibitors and promoters of ion channels in drug discovery, it would be beneficial to conduct a solution exchange of droplets to introduce membrane proteins and to apply or wash-out the chemicals. In this study, we propose a droplet contact method that allows for the solution exchange of droplets via microfluidic channels. We experimentally and numerically investigated the bilayer stability with respect to exchanging flow rates, and then demonstrated a binding assay of an alpha-hemolysin using one of its blockers. The solution exchange in this system was conducted in less than 20 s without rupturing the membrane. We believe that the proposed system will enhance the efficiency of ion channel analyses.

  18. Sensitive Protein Detection and Quantification in Paper-Based Microfluidics for the Point of Care.

    PubMed

    Anderson, Caitlin E; Shah, Kamal G; Yager, Paul

    2017-01-01

    The design of appropriate diagnostic assays for the point of care requires development of suitable biosensors, detection methods, and diagnostic platforms for sensitive, quantitative detection of biological analytes. Protein targets in particular are especially challenging to detect quantitatively and sensitively due to the lack of amplification strategies akin to nucleic acid amplification. However, recent advances in transducer and biosensor design, new detection labels, and paper-based microfluidics may realize the goal of sensitive, fast, portable, and low-cost protein detection. In this review, we discuss the biochemistry, optics, and engineering advances that may be leveraged to design such a sensitive protein diagnostic assay. The binding kinetics, mechanisms of binding in porous networks, and potential transducers are explained in detail. We discuss the relative merits of various optical detection strategies, potential detection labels, optical readout approaches, and image-processing techniques that are amenable to point-of-care use. To conclude, we present a systematic analysis of potential approaches to enhance the sensitivity of paper-based assays. The assay development framework presented here provides bioassay developers a strategy to methodically enhance the sensitivity and point-of-care suitability of protein diagnostics.

  19. Optofluidic encapsulation and manipulation of silicon microchips using image processing based optofluidic maskless lithography and railed microfluidics.

    PubMed

    Chung, Su Eun; Lee, Seung Ah; Kim, Jiyun; Kwon, Sunghoon

    2009-10-07

    We demonstrate optofluidic encapsulation of silicon microchips using image processing based optofluidic maskless lithography and manipulation using railed microfluidics. Optofluidic maskless lithography is a dynamic photopolymerization technique of free-floating microstructures within a fluidic channel using spatial light modulator. Using optofluidic maskless lithography via computer-vision aided image processing, polymer encapsulants are fabricated for chip protection and guiding-fins for efficient chip conveying within a fluidic channel. Encapsulated silicon chips with guiding-fins are assembled using railed microfluidics, which is an efficient guiding and heterogeneous self-assembly system of microcomponents. With our technology, externally fabricated silicon microchips are encapsulated, fluidically guided and self-assembled potentially enabling low cost fluidic manipulation and assembly of integrated circuits.

  20. A Contact-Imaging Based Microfluidic Cytometer with Machine-Learning for Single-Frame Super-Resolution Processing

    PubMed Central

    Huang, Xiwei; Guo, Jinhong; Wang, Xiaolong; Yan, Mei; Kang, Yuejun; Yu, Hao

    2014-01-01

    Lensless microfluidic imaging with super-resolution processing has become a promising solution to miniaturize the conventional flow cytometer for point-of-care applications. The previous multi-frame super-resolution processing system can improve resolution but has limited cell flow rate and hence low throughput when capturing multiple subpixel-shifted cell images. This paper introduces a single-frame super-resolution processing with on-line machine-learning for contact images of cells. A corresponding contact-imaging based microfluidic cytometer prototype is demonstrated for cell recognition and counting. Compared with commercial flow cytometer, less than 8% error is observed for absolute number of microbeads; and 0.10 coefficient of variation is observed for cell-ratio of mixed RBC and HepG2 cells in solution. PMID:25111497

  1. Isolation and Analysis of Rare Norovirus Recombinants from Coinfected Mice Using Drop-Based Microfluidics

    PubMed Central

    Zhang, Huidan; Cockrell, Shelley K.; Kolawole, Abimbola O.; Rotem, Assaf; Serohijos, Adrian W. R.; Chang, Connie B.; Tao, Ye; Mehoke, Thomas S.; Han, Yulong; Lin, Jeffrey S.; Giacobbi, Nicholas S.; Feldman, Andrew B.; Shakhnovich, Eugene; Weitz, David A.; Wobus, Christiane E.

    2015-01-01

    switching by the virus-encoded RNA-dependent RNA polymerase (RdRP). However, factors that govern the frequency and positions of recombination in an infected organism remain largely unknown. This work leverages advances in the applied physics of drop-based microfluidics to isolate and sequence rare recombinants arising from the coinfection of mice with two distinct strains of murine norovirus. This study is the first to detect and analyze norovirus recombination in an animal model. PMID:25972549

  2. Rapid and amplification-free detection of fish pathogens by utilizing a molecular beacon-based microfluidic system.

    PubMed

    Su, Yi-Chih; Wang, Chih-Hung; Chang, Wen-Hsin; Chen, Tzong-Yueh; Lee, Gwo-Bin

    2015-01-15

    Nervous necrosis virus (NNV) and iridovirus are highly infectious pathogens that can cause lethal diseases in various species of fish. These infectious diseases have no effective treatments and the mortality rate is over 80%, which could cause dramatic economic losses in the aquaculture industry. Conventional diagnostic methods of NNV or iridovirus infected fishes, such as virus culture, enzyme-linked immunosorbent assays and nucleic acid assays usually require time-consuming and complex procedures performed by specialized technicians with delicate laboratory facilities. Rapid, simple, accurate and on-site detection of NNV and iridovirus infections would enable timely preventive measures such as immediate sacrifice of infected fishes, and is therefore critically needed for the aquaculture industry. In this study, a microfluidic-based assay that employ magnetic beads conjugated with viral deoxyribonucleic acid (DNA) capturing probes and fluorescent DNA molecular beacons were developed to rapidly detect NNV and iridovirus. Importantly, this new assay was realized in an integrated microfluidic system with a custom-made control system. With this approach, direct and automated NNV and iridovirus detection from infected fishes can be achieved in less than 30 min. Therefore, this molecular-beacon based microfluidic system presents a potentially promising tool for rapid diagnosis of fish pathogens in the field in the future.

  3. Microspot-based ELISA in microfluidics: chemiluminescence and colorimetry detection using integrated thin-film hydrogenated amorphous silicon photodiodes.

    PubMed

    Novo, Pedro; Prazeres, Duarte Miguel França; Chu, Virginia; Conde, João Pedro

    2011-12-07

    Microfluidic technology has the potential to decrease the time of analysis and the quantity of sample and reactants required in immunoassays, together with the potential of achieving high sensitivity, multiplexing, and portability. A lab-on-a-chip system was developed and optimized using optical and fluorescence microscopy. Primary antibodies are adsorbed onto the walls of a PDMS-based microchannel via microspotting. This probe antibody is then recognised using secondary FITC or HRP labelled antibodies responsible for providing fluorescence or chemiluminescent and colorimetric signals, respectively. The system incorporated a micron-sized thin-film hydrogenated amorphous silicon photodiode microfabricated on a glass substrate. The primary antibody spots in the PDMS-based microfluidic were precisely aligned with the photodiodes for the direct detection of the antibody-antigen molecular recognition reactions using chemiluminescence and colorimetry. The immunoassay takes ~30 min from assay to the integrated detection. The conditions for probe antibody microspotting and for the flow-through ELISA analysis in the microfluidic format with integrated detection were defined using antibody solutions with concentrations in the nM-μM range. Sequential colorimetric or chemiluminescence detection of specific antibody-antigen molecular recognition was quantitatively detected using the photodiode. Primary antibody surface densities down to 0.182 pmol cm(-2) were detected. Multiplex detection using different microspotted primary antibodies was demonstrated.

  4. Portable microfluidic and smartphone-based devices for monitoring of cardiovascular diseases at the point of care.

    PubMed

    Hu, Jie; Cui, Xingye; Gong, Yan; Xu, Xiayu; Gao, Bin; Wen, Ting; Lu, Tian Jian; Xu, Feng

    2016-01-01

    Cardiovascular diseases (CVDs) are the main causes of morbidity and mortality in the world where about 4 in every 5 CVD deaths happen in low- and middle-income countries (LMICs). Most CVDs are preventable and curable, which is largely dependent on timely and effective interventions, including diagnosis, prognosis and therapeutic monitoring. However, these interventions are high-cost in high income countries and are usually lacking in LMICs. Thanks to the rapid development of microfluidics and nanotechnology, lots of portable analytical devices are developed for detection of CVDs at the point-of-care (POC). In the meantime, smartphone, as a versatile and powerful handheld tool, has been employed not only as a reader for microfluidic assays, but also as an analyzer for physiological indexes. In this review, we present a comprehensive introduction of the current status and potential development direction on POC diagnostics for CVDs. First of all, we introduce some main facts about CVDs and their standard diagnostic procedures and methods. Second, we discuss about both commercially available POC devices and developed prototypes for detection of CVDs via immunoassays. Subsequently, we report the advances in smartphone-based readout for microfluidic assays. Finally, we present some examples using smartphone, individually or combined with other components or devices, for CVD monitoring. We envision an integrated smartphone-based system capable of functioning blood tests, disease examination, and imaging will come in the future.

  5. Microfluidic immunomagnetic cell separation from whole blood.

    PubMed

    Bhuvanendran Nair Gourikutty, Sajay; Chang, Chia-Pin; Puiu, Poenar Daniel

    2016-02-01

    Immunomagnetic-based separation has become a viable technique for the separation of cells and biomolecules. Here we report on the design and analysis of a simple and efficient microfluidic device for high throughput and high efficiency capture of cells tagged with magnetic particles. This is made possible by using a microfluidic chip integrated with customized arrays of permanent magnets capable of creating large magnetic field gradients, which determine the effective capturing of the tagged cells. This method is based on manipulating the cells which are under the influence of a combination of magnetic and fluid dynamic forces in a fluid under laminar flow through a microfluidic chip. A finite element analysis (FEA) model is developed to analyze the cell separation process and predict its behavior, which is validated subsequently by the experimental results. The magnetic field gradients created by various arrangements of magnetic arrays have been simulated using FEA and the influence of these field gradients on cell separation has been studied with the design of our microfluidic chip. The proof-of-concept for the proposed technique is demonstrated by capturing white blood cells (WBCs) from whole human blood. CD45-conjugated magnetic particles were added into whole blood samples to label WBCs and the mixture was flown through our microfluidic device to separate the labeled cells. After the separation process, the remaining WBCs in the elute were counted to determine the capture efficiency, and it was found that more than 99.9% WBCs have been successfully separated from whole blood. The proposed design can be used for positive selection as well as for negative enrichment of rare cells.

  6. Formic acid microfluidic fuel cell based on well-defined Pd nanocubes

    NASA Astrophysics Data System (ADS)

    Moreno-Zuria, A.; Dector, A.; Arjona, N.; Guerra-Balcázar, M.; Ledesma-García, J.; Esquivel, J. P.; Sabaté, N.; Arrriaga, L. G.; Chávez-Ramírez, A. U.

    2013-12-01

    Microfluidic fuel cells (μFFC) are emerging as a promising solution for small-scale power demands. The T-shaped architecture of the μFFC promotes a laminar flow regimen between the catholyte and anolyte streams excluding the use of a membrane, this property allows a simplest design and the use of several micromachining techniques based on a lab-on-chip technologies. This work presents a combination of new materials and low cost fabrication processes to develop a light, small, flexible and environmental friendly device able to supply the energy demand of some portable devices. Well-defined and homogeneous Pd nanocubes which exhibited the (100) preferential crystallographic plane were supported on Vulcan carbon and used as anodic electrocatalyst in a novel and compact design of a SU-8 μFFC feeded with formic acid as fuel. The SU-8 photoresist properties and the organic microelectronic technology were important factors to reduce the dimensions of the μFFC structure. The results obtained from polarization and power density curves exhibited the highest power density (8.3 mW cm-2) reported in literature for direct formic acid μFFCs.

  7. A microfluidics-based in vitro model of the gastrointestinal human–microbe interface

    PubMed Central

    Shah, Pranjul; Fritz, Joëlle V.; Glaab, Enrico; Desai, Mahesh S.; Greenhalgh, Kacy; Frachet, Audrey; Niegowska, Magdalena; Estes, Matthew; Jäger, Christian; Seguin-Devaux, Carole; Zenhausern, Frederic; Wilmes, Paul

    2016-01-01

    Changes in the human gastrointestinal microbiome are associated with several diseases. To infer causality, experiments in representative models are essential, but widely used animal models exhibit limitations. Here we present a modular, microfluidics-based model (HuMiX, human–microbial crosstalk), which allows co-culture of human and microbial cells under conditions representative of the gastrointestinal human–microbe interface. We demonstrate the ability of HuMiX to recapitulate in vivo transcriptional, metabolic and immunological responses in human intestinal epithelial cells following their co-culture with the commensal Lactobacillus rhamnosus GG (LGG) grown under anaerobic conditions. In addition, we show that the co-culture of human epithelial cells with the obligate anaerobe Bacteroides caccae and LGG results in a transcriptional response, which is distinct from that of a co-culture solely comprising LGG. HuMiX facilitates investigations of host–microbe molecular interactions and provides insights into a range of fundamental research questions linking the gastrointestinal microbiome to human health and disease. PMID:27168102

  8. Model-based analysis of a dielectrophoretic microfluidic device for field-flow fractionation.

    PubMed

    Mathew, Bobby; Alazzam, Anas; Abutayeh, Mohammad; Stiharu, Ion

    2016-08-01

    We present the development of a dynamic model for predicting the trajectory of microparticles in microfluidic devices, employing dielectrophoresis, for Hyperlayer field-flow fractionation. The electrode configuration is such that multiple finite-sized electrodes are located on the top and bottom walls of the microchannel; the electrodes on the walls are aligned with each other. The electric potential inside the microchannel is described using the Laplace equation while the microparticles' trajectory is described using equations based on Newton's second law. All equations are solved using finite difference method. The equations of motion account for forces including inertia, buoyancy, drag, gravity, virtual mass, and dielectrophoresis. The model is used for parametric study; the geometric parameters analyzed include microparticle radius, microchannel depth, and electrode/spacing lengths while volumetric flow rate and actuation voltage are the two operating parameters considered in the study. The trajectory of microparticles is composed of transient and steady state phases; the trajectory is influenced by all parameters. Microparticle radius and volumetric flow rate, above the threshold, do not influence the steady state levitation height; microparticle levitation is not possible below the threshold of the volumetric flow rate. Microchannel depth, electrode/spacing lengths, and actuation voltage influence the steady-state levitation height.

  9. A Microfluidic Paper-Based Analytical Device for Rapid Quantification of Particulate Chromium

    PubMed Central

    Rattanarat, Poomrat; Dungchai, Wijitar; Cate, David M.; Siangproh, Weena; Volckens, John; Chailapakul, Orawon; Henry, Charles S.

    2013-01-01

    Occupational exposure to Cr is concerning because of its myriad of health effects. Assessing chromium exposure is also cost and resource intensive because the analysis typically uses sophisticated instrumental techniques like Inductively-Coupled Plasma-Mass Spectrometry (ICP-MS). Here, we report a novel, simple, inexpensive microfluidic paper-based analytical device (µPAD) for measuring total Cr in airborne particulate matter. In the µPAD, tetravalent cerium (Ce(IV)) was used in a pretreatment zone to oxidize all soluble Cr to Cr(VI). After elution to the detection zone, Cr(VI) reacts with 1,5-diphenylcarbazide (1,5- DPC) forming 1,5-diphenylcarbazone (DPCO) and Cr(III). The resulting Cr(III) forms a distinct purple colored complex with the DPCO. As proof-of-principle, particulate matter (PM) collected on a sample filter was analyzed with the µPAD to quantify the mass of total Cr. A log-linear working range (0.23–3.75 µg; r2=0.998) between Cr and color intensity was obtained with a detection limit of 0.12 µg. For validation, a certified reference containing multiple competing metals was analyzed. Quantitative agreement was obtained between known Cr levels in the sample and the Cr measured using the µPAD. PMID:24120167

  10. Microfluidic-based fabrication, characterization and magnetic functionalization of microparticles with novel internal anisotropic structure

    NASA Astrophysics Data System (ADS)

    Qiu, Yang; Wang, Fei; Liu, Ying-Mei; Wang, Wei; Chu, Liang-Yin; Wang, Hua-Lin

    2015-08-01

    Easy fabrication and independent control of the internal and external morphologies of core-shell microparticles still remain challenging. Core-shell microparticle comprised of a previously unknown internal anisotropic structure and a spherical shell was fabricated by microfluidic-based emulsificaiton and photopolymerization. The interfacial and spatial 3D morphology of the anisotropic structure were observed by SEM and micro-CT respectively. Meanwhile, a series of layer-by-layer scans of the anisotropic structure were obtained via the micro-CT, which enhanced the detail characterization and analysis of micro materials. The formation mechanism of the internal anisotropic structure may be attributed to solution-directed diffusion caused by the semipermeable membrane structure and chemical potential difference between inside and outside of the semipermeable membrane-like polymerized shell. The morphology evolution of the anisotropic structure was influenced and controlled by adjusting reaction parameters including polymerization degree, polymerization speed, and solute concentration difference. The potential applications of these microparticles in microrheological characterization and image enhancement were also proposed by embedding magnetic nanoparticles in the inner core.

  11. Droplet-based microfluidic platform for high-throughput, multi-parameter screening of photosensitizer activity.

    PubMed

    Cho, Soongwon; Kang, Dong-Ku; Sim, Steven; Geier, Florian; Kim, Jin-Young; Niu, Xize; Edel, Joshua B; Chang, Soo-Ik; Wootton, Robert C R; Elvira, Katherine S; deMello, Andrew J

    2013-09-17

    We present a fully integrated droplet-based microfluidic platform for the high-throughput assessment of photodynamic therapy photosensitizer (PDT) efficacy on Escherichia coli. The described platform is able to controllably encapsulate cells and photosensitizer within pL-volume droplets, incubate the droplets over the course of several days, add predetermined concentrations of viability assay agents, expose droplets to varying doses of electromagnetic radiation, and detect both live and dead cells online to score cell viability. The viability of cells after encapsulation and incubation is assessed in a direct fashion, and the viability scoring method is compared to model live/dead systems for calibration. Final results are validated against conventional colony forming unit assays. In addition, we show that the platform can be used to perform concurrent measurements of light and dark toxicity of the PDT agents and that the platform allows simultaneous measurement of experimental parameters that include dark toxicity, photosensitizer concentration, light dose, and oxygenation levels for the development and testing of PDT agents.

  12. Simulation and experimentation of a microfluidic device based on electrowetting on dielectric.

    PubMed

    Jang, Ling-Sheng; Lin, Guo-Hua; Lin, Yi-Liang; Hsu, Chih-Yuan; Kan, Wai-Hong; Chen, Chiun-Hsun

    2007-12-01

    Electrowetting on dielectric (EWOD) moving fluid by surface tension effects offers some advantages, including simplicity of fabrication, control of minute volumes, rapid mixing, low cost and others. This work presents a numerical model using a commercial software, CFD-ACE+, and an EWOD system including a microfluidic device, a microprocessor, electric circuits, a LCD module, a keypad, a power supply and a power amplifier. The EWOD model based on a reduced form of the mass conservation and momentum equations is adopted to simulate the fluid dynamics of the droplets. The EWOD device consists of the 2 x 2 mm bottom electrodes (Au/Cr), a dielectric layer of 3,000 A nitride, 500 A Teflon and a piece of indium tin oxide (ITO)-coated glass as the top electrode. The complete EWOD phenomenon is elucidated by comparing simulation with the experimental data on droplet transportation, cutting and creation. In transportation testing, the speed of the droplet is 6 mm/s at 40 V(dc). In addition, the droplet division process takes 0.12 s at 60 V(dc) in the current case. Finally, a 347 nl droplet is successfully created from an on-chip reservoir at 60 V(dc).

  13. Tetrazine-based chemistry for nitrite determination in a paper microfluidic device.

    PubMed

    Ortiz-Gomez, Inmaculada; Ortega-Muñoz, Mariano; Salinas-Castillo, Alfonso; Álvarez-Bermejo, José Antonio; Ariza-Avidad, Maria; de Orbe-Payá, Ignacio; Santoyo-Gonzalez, Francisco; Capitan-Vallvey, Luis Fermin

    2016-11-01

    We present a new chemistry to determine nitrites implemented in a microfluidic paper-based analytical device (µPAD). The device is fabricated in cellulose paper with a sample reception area and three replicate detection areas with recognition chemistry immobilized by adsorption. The method involves the use of nitrite in an acid medium reaction to generate nitrous acid, which produces the oxidation of s-dihydrotetrazine: 1,2-dihydro-3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DHBPTz), which change the detection zone from colorless to pink. We used a digital camera and smartphone for the quantitative analysis of nitrite with the color coordinate S of the HSV color space as the analytical parameter. Parameters such as concentration and volume of s-dihydrotetrazine, pH, sample volume and reaction time were studied. The detection limit for this method is 1.30µM nitrite. To estimate the selectivity of the method an interference study of common ions in water samples was performed. The procedure was applied to natural water and compared with reference procedures.

  14. Microchip-based cellular biochemical systems for practical applications and fundamental research: from microfluidics to nanofluidics.

    PubMed

    Xu, Yan; Jang, Kihoon; Yamashita, Tadahiro; Tanaka, Yo; Mawatari, Kazuma; Kitamori, Takehiko

    2012-01-01

    By combining cell technology and microchip technology, innovative cellular biochemical tools can be created from the microscale to the nanoscale for both practical applications and fundamental research. On the microscale level, novel practical applications taking advantage of the unique capabilities of microfluidics have been accelerated in clinical diagnosis, food safety, environmental monitoring, and drug discovery. On the other hand, one important trend of this field is further downscaling of feature size to the 10(1)-10(3) nm scale, which we call extended-nano space. Extended-nano space technology is leading to the creation of innovative nanofluidic cellular and biochemical tools for analysis of single cells at the single-molecule level. As a pioneering group in this field, we focus not only on the development of practical applications of cellular microchip devices but also on fundamental research to initiate new possibilities in the field. In this paper, we review our recent progress on tissue reconstruction, routine cell-based assays on microchip systems, and preliminary fundamental method for single-cell analysis at the single-molecule level with integration of the burgeoning technologies of extended-nano space.

  15. Microfluidic-based fabrication, characterization and magnetic functionalization of microparticles with novel internal anisotropic structure

    PubMed Central

    Qiu, Yang; Wang, Fei; Liu, Ying-Mei; Wang, Wei; Chu, Liang-Yin; Wang, Hua-Lin

    2015-01-01

    Easy fabrication and independent control of the internal and external morphologies of core-shell microparticles still remain challenging. Core-shell microparticle comprised of a previously unknown internal anisotropic structure and a spherical shell was fabricated by microfluidic-based emulsificaiton and photopolymerization. The interfacial and spatial 3D morphology of the anisotropic structure were observed by SEM and micro-CT respectively. Meanwhile, a series of layer-by-layer scans of the anisotropic structure were obtained via the micro-CT, which enhanced the detail characterization and analysis of micro materials. The formation mechanism of the internal anisotropic structure may be attributed to solution-directed diffusion caused by the semipermeable membrane structure and chemical potential difference between inside and outside of the semipermeable membrane-like polymerized shell. The morphology evolution of the anisotropic structure was influenced and controlled by adjusting reaction parameters including polymerization degree, polymerization speed, and solute concentration difference. The potential applications of these microparticles in microrheological characterization and image enhancement were also proposed by embedding magnetic nanoparticles in the inner core. PMID:26268148

  16. Patterned electrode-based amperometric gas sensor for direct nitric oxide detection within microfluidic devices.

    PubMed

    Cha, Wansik; Tung, Yi-Chung; Meyerhoff, Mark E; Takayama, Shuichi

    2010-04-15

    This article describes a thin amperometric nitric oxide (NO) sensor that can be microchannel embedded to enable direct real-time detection of NO produced by cells cultured within the microdevice. A key for achieving the thin ( approximately 1 mm) planar sensor configuration required for sensor-channel integration is the use of gold/indium-tin oxide patterned electrode directly on a porous polymer membrane (pAu/ITO) as the base working electrode. The electrochemically deposited Au-hexacyanoferrate layer on pAu/ITO is used to catalyze NO oxidation to nitrite at lower applied potentials (0.65-0.75 V vs Ag/AgCl) and stabilize current output. Furthermore, use of a gas-permeable membrane to separate internal sensor compartments from the sample phase imparts excellent NO selectivity over common interfering agents (e.g., nitrite, ascorbate, ammonia, etc.) present in culture media and biological fluids. The optimized sensor design reversibly detects NO down to the approximately 1 nM level in stirred buffer and <10 nM in flowing buffer when integrated within a polymeric microfluidic device. We demonstrate utility of the channel-embedded sensor by monitoring NO generation from macrophages cultured within non-gas-permeable microchannels, as they are stimulated with endotoxin.

  17. Determination of Apparent Amylose Content in Rice by Using Paper-Based Microfluidic Chips.

    PubMed

    Hu, Xianqiao; Lu, Lin; Fang, Changyun; Duan, Binwu; Zhu, Zhiwei

    2015-11-11

    Determination of apparent amylose content in rice is a key function for rice research and the rice industry. In this paper, a novel approach with paper-based microfluidic chip is reported to determine apparent amylose content in rice. The conventional color reaction between amylose and iodine was employed. Blue color of amylose-iodine complex generated on-chip was converted to gray and measured with Photoshop after the colored chip was scanned. The method for preparation of the paper chip is described. In situ generation of iodine for on-chip color reaction was designed, and factors influencing color reaction were investigated in detail. Elimination of yellow color interference of excess iodine by exploiting color removal function of Photoshop was presented. Under the optimized conditions, apparent amylose content in rice ranging from 1.5 to 26.4% can be determined, and precision was 6.3%. The analytical results obtained with the developed approach were in good agreement with those with the continuous flow analyzer method.

  18. Robust Extraction Interface for Coupling Droplet-Based and Continuous Flow Microfluidics

    SciTech Connect

    Sun, Xuefei; Tang, Keqi; Smith, Richard D.; Kelly, Ryan T.

    2012-03-07

    Reliable and highly efficient extraction of droplets from oil to aqueous phase is key for downstream coupling with chemical separations and nonoptical detection methods such as amperometry and mass spectrometry. This paper presents an improved interface providing robust extraction for droplet-based poly(dimethylsiloxane) (PDMS) microfluidic devices. The extraction interface consists of an array of cylindrical posts with narrow apertures in between. The aqueous flow channel into which droplets coalesced was simply and selectively modified to be hydrophilic, while the continuous oil phase flow channel that contained encapsulated aqueous droplets retained a hydrophobic surface. The different surfaces on both sides of the extraction region form a highly stable liquid interface between the two immiscible phases, allowing rapid droplet transfer to the aqueous stream. Entire droplets could be completely extracted within broad ranges of aqueous and oil flow rates (0 - 1 and 0.1 - 1 uL/min, respectively). After extraction, the droplet contents could be transported electrophoretically or by pressure-driven flow to a monolithically integrated emitter for nano-electrospray ionization mass spectrometry (nanoESI-MS) analysis. This interface should be amenable to the separation and identification of droplet contents and on-line monitoring of in-droplet reactions.

  19. Chemiluminescence detection for microfluidic cloth-based analytical devices (μCADs).

    PubMed

    Guan, Wenrong; Zhang, Chunsun; Liu, Feifei; Liu, Min

    2015-10-15

    In this work, we report the first demonstration of chemiluminescence (CL) detection for microfluidic cloth-based analytical devices (μCADs). Wax screen-printing is used to make cloth channels or chambers, and enzyme-catalyzed CL reactions are imaged using an inexpensive charge coupled device (CCD). We first evaluate the relationship between the wicking rate and the length/width of cloth channel. For our device, the channel length and width between the loading and detection chambers are optimized to be 10mm and 3mm. Thus, the detection procedure can be accomplished in about 15s on a cloth-based device (15 × 30 mm(2)) by using 25-μL sample spotted on it. Next, several parameters affecting cloth-based CL intensity are studied, including exposure time, pH, and concentrations of luminol and enzyme. Under optimal conditions, a linear relationship is obtained between CL intensity and hydrogen peroxide (H2O2) concentrations in the range of 0.5-5mM with a detection limit of 0.46 mM. Finally, the utility of cloth-based CL is demonstrated for determination of H2O2 residues in meat samples. On our device, the chicken meat soaked for 6h with 3% H2O2 can be detected. Moreover, the supernatant of grinded meat sample can be directly applied, without need for other treatments. We believe that μCADs with CL detection could provide a new platform of rapid and low-cost assays for use in areas such as food detection and environmental monitoring.

  20. Understanding wax screen-printing: a novel patterning process for microfluidic cloth-based analytical devices.

    PubMed

    Liu, Min; Zhang, Chunsun; Liu, Feifei

    2015-09-03

    In this work, we first introduce the fabrication of microfluidic cloth-based analytical devices (μCADs) using a wax screen-printing approach that is suitable for simple, inexpensive, rapid, low-energy-consumption and high-throughput preparation of cloth-based analytical devices. We have carried out a detailed study on the wax screen-printing of μCADs and have obtained some interesting results. Firstly, an analytical model is established for the spreading of molten wax in cloth. Secondly, a new wax screen-printing process has been proposed for fabricating μCADs, where the melting of wax into the cloth is much faster (∼5 s) and the heating temperature is much lower (75 °C). Thirdly, the experimental results show that the patterning effects of the proposed wax screen-printing method depend to a certain extent on types of screens, wax melting temperatures and melting time. Under optimized conditions, the minimum printing width of hydrophobic wax barrier and hydrophilic channel is 100 μm and 1.9 mm, respectively. Importantly, the developed analytical model is also well validated by these experiments. Fourthly, the μCADs fabricated by the presented wax screen-printing method are used to perform a proof-of-concept assay of glucose or protein in artificial urine with rapid high-throughput detection taking place on a 48-chamber cloth-based device and being performed by a visual readout. Overall, the developed cloth-based wax screen-printing and arrayed μCADs should provide a new research direction in the development of advanced sensor arrays for detection of a series of analytes relevant to many diverse applications.

  1. Perspectives in flow-based microfluidic gradient generators for characterizing bacterial chemotaxis

    PubMed Central

    Wolfram, Christopher J.; Rubloff, Gary W.; Luo, Xiaolong

    2016-01-01

    Chemotaxis is a phenomenon which enables cells to sense concentrations of certain chemical species in their microenvironment and move towards chemically favorable regions. Recent advances in microbiology have engineered the chemotactic properties of bacteria to perform novel functions, but traditional methods of characterizing chemotaxis do not fully capture the associated cell motion, making it difficult to infer mechanisms that link the motion to the microbiology which induces it. Microfluidics offers a potential solution in the form of gradient generators. Many of the gradient generators studied to date for this application are flow-based, where a chemical species diffuses across the laminar flow interface between two solutions moving through a microchannel. Despite significant research efforts, flow-based gradient generators have achieved mixed success at accurately capturing the highly subtle chemotactic responses exhibited by bacteria. Here we present an analysis encompassing previously published versions of flow-based gradient generators, the theories that govern their gradient-generating properties, and new, more practical considerations that result from experimental factors. We conclude that flow-based gradient generators present a challenge inherent to their design in that the residence time and gradient decay must be finely balanced, and that this significantly narrows the window for reliable observation and quantification of chemotactic motion. This challenge is compounded by the effects of shear on an ellipsoidal bacterium that causes it to preferentially align with the direction of flow and subsequently suppresses the cross-flow chemotactic response. These problems suggest that a static, non-flowing gradient generator may be a more suitable platform for chemotaxis studies in the long run, despite posing greater difficulties in design and fabrication. PMID:27917249

  2. A Label-Free Microfluidic Biosensor for Activity Detection of Single Microalgae Cells Based on Chlorophyll Fluorescence

    PubMed Central

    Wang, Junsheng; Sun, Jinyang; Song, Yongxin; Xu, Yongyi; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

    2013-01-01

    Detection of living microalgae cells is very important for ballast water treatment and analysis. Chlorophyll fluorescence is an indicator of photosynthetic activity and hence the living status of plant cells. In this paper, we developed a novel microfluidic biosensor system that can quickly and accurately detect the viability of single microalgae cells based on chlorophyll fluorescence. The system is composed of a laser diode as an excitation light source, a photodiode detector, a signal analysis circuit, and a microfluidic chip as a microalgae cell transportation platform. To demonstrate the utility of this system, six different living and dead algae samples (Karenia mikimotoi Hansen, Chlorella vulgaris, Nitzschia closterium, Platymonas subcordiformis, Pyramidomonas delicatula and Dunaliella salina) were tested. The developed biosensor can distinguish clearly between the living microalgae cells and the dead microalgae cells. The smallest microalgae cells that can be detected by using this biosensor are 3 μm ones. Even smaller microalgae cells could be detected by increasing the excitation light power. The developed microfluidic biosensor has great potential for in situ ballast water analysis. PMID:24287532

  3. EWOD (electrowetting on dielectric) digital microfluidics powered by finger actuation.

    PubMed

    Peng, Cheng; Zhang, Zhongning; Kim, Chang-Jin C J; Ju, Y Sungtaek

    2014-03-21

    We report finger-actuated digital microfluidics (F-DMF) based on the manipulation of discrete droplets via the electrowetting on dielectric (EWOD) phenomenon. Instead of requiring an external power supply, our F-DMF uses piezoelectric elements to convert mechanical energy produced by human fingers to electric voltage pulses for droplet actuation. Voltage outputs of over 40 V are provided by single piezoelectric elements, which is necessary for oil-free EWOD devices with thin (typically <1 μm) dielectric layers. Higher actuation voltages can be provided using multiple piezoelectric elements connected in series when needed. Using this energy conversion scheme, we confirmed basic modes of EWOD droplet operation, such as droplet transport, splitting and merging. Using two piezoelectric elements in series, we also successfully demonstrated applications of F-DMF for glucose detection and immunoassay. Not requiring power sources, F-DMF offers intriguing paths for various portable and other microfluidic applications.

  4. Interfacial tension based on-chip extraction of microparticles confined in microfluidic Stokes flows

    NASA Astrophysics Data System (ADS)

    Huang, Haishui; He, Xiaoming

    2014-10-01

    Microfluidics involving two immiscible fluids (oil and water) has been increasingly used to produce hydrogel microparticles with wide applications. However, it is difficult to extract the microparticles out of the microfluidic Stokes flows of oil that have a Reynolds number (the ratio of inertia to viscous force) much less than one, where the dominant viscous force tends to drive the microparticles to move together with the surrounding oil. Here, we present a passive method for extracting hydrogel microparticles in microfluidic Stokes flow from oil into aqueous extracting solution on-chip by utilizing the intrinsic interfacial tension between oil and the microparticles. We further reveal that the thickness of an "extended confining layer" of oil next to the interface between oil and aqueous extracting solution must be smaller than the radius of microparticles for effective extraction. This method uses a simple planar merging microchannel design that can be readily fabricated and further integrated into a fluidic system to extract microparticles for wide applications.

  5. Rapid fabrication of microfluidic chips based on the simplest LED lithography

    NASA Astrophysics Data System (ADS)

    Li, Yue; Wu, Ping; Luo, Zhaofeng; Ren, Yuxuan; Liao, Meixiang; Feng, Lili; Li, Yuting; He, Liqun

    2015-05-01

    Microfluidic chips are generally fabricated by a soft lithography method employing commercial lithography equipment. These heavy machines require a critical room environment and high lamp power, and the cost remains too high for most normal laboratories. Here we present a novel microfluidics fabrication method utilizing a portable ultraviolet (UV) LED as an alternative UV source for photolithography. With this approach, we can repeat several common microchannels as do these conventional commercial exposure machines, and both the verticality of the channel sidewall and lithography resolution are proved to be acceptable. Further microfluidics applications such as mixing, blood typing and microdroplet generation are implemented to validate the practicability of the chips. This simple but innovative method decreases the cost and requirement of chip fabrication dramatically and may be more popular with ordinary laboratories.

  6. Liquid metal enabled microfluidics.

    PubMed

    Khoshmanesh, Khashayar; Tang, Shi-Yang; Zhu, Jiu Yang; Schaefer, Samira; Mitchell, Arnan; Kalantar-Zadeh, Kourosh; Dickey, Michael D

    2017-03-14

    Several gallium-based liquid metal alloys are liquid at room temperature. As 'liquid', such alloys have a low viscosity and a high surface tension while as 'metal', they have high thermal and electrical conductivities, similar to mercury. However, unlike mercury, these liquid metal alloys have low toxicity and a negligible vapor pressure, rendering them much safer. In comparison to mercury, the distinguishing feature of these alloys is the rapid formation of a self-limiting atomically thin layer of gallium oxide over their surface when exposed to oxygen. This oxide layer changes many physical and chemical properties of gallium alloys, including their interfacial and rheological properties, which can be employed and modulated for various applications in microfluidics. Injecting liquid metal into microfluidic structures has been extensively used to pattern and encapsulate highly deformable and reconfigurable electronic devices including electrodes, sensors, antennas, and interconnects. Likewise, the unique features of liquid metals have been employed for fabricating miniaturized microfluidic components including pumps, valves, heaters, and electrodes. In this review, we discuss liquid metal enabled microfluidic components, and highlight their desirable attributes including simple fabrication, facile integration, stretchability, reconfigurability, and low power consumption, with promising applications for highly integrated microfluidic systems.

  7. A microfluidic system for saliva-based detection of infectious diseases.

    PubMed

    Chen, Zongyuan; Mauk, Michael G; Wang, Jing; Abrams, William R; Corstjens, Paul L A M; Niedbala, R Sam; Malamud, Daniel; Bau, Haim H

    2007-03-01

    A "lab-on-a-chip" system for detecting bacterial pathogens in oral fluid samples is described. The system comprises: (1) an oral fluid sample collector; (2) a disposable, plastic microfluidic cassette ("chip") for sample processing including immunochromatographic assay with a nitrocellulose lateral flow strip; (3) a platform that controls the cassette operation by providing metered quantities of reagents, temperature regulation, valve actuation; and (4) a laser scanner to interrogate the lateral flow strip. The microfluidic chip hosts a fluidic network for cell lysis, nucleic acid extraction and isolation, PCR, and labeling of the PCR product with bioconjugated, upconverting phosphor particles for detection on the lateral flow strip.

  8. A Microfluidic Device for Immunoassay-Based Protein Analysis of Single E. coli Bacteria.

    PubMed

    Stratz, Simone; Dittrich, Petra S

    2015-01-01

    We present a method suitable for quantitative analysis of intracellular proteins, metabolites and secondary messengers of single bacterial cells. The method integrates the concept of immunoassays on a microfluidic device that facilitates single cell trapping and isolating in a small volume of a few tens of picoliters. Combination of the benefits of microfluidic systems for single cell analysis with the high analytical selectivity and sensitivity of immunoassays enables the detection of even low abundant intracellular analytes which occur only at a few hundred copies per bacterium.

  9. Protein crystallization using microfluidic technologies based on valves, droplets, and SlipChip.

    PubMed

    Li, Liang; Ismagilov, Rustem F

    2010-01-01

    To obtain protein crystals, researchers must search for conditions in multidimensional chemical space. Empirically, thousands of crystallization experiments are carried out to screen various precipitants at multiple concentrations. Microfluidics can manipulate fluids on a nanoliter scale, and it affects crystallization twofold. First, it miniaturizes the experiments that can currently be done on a larger scale and enables crystallization of proteins that are available only in small amounts. Second, it offers unique experimental approaches that are difficult or impossible to implement on a larger scale. Ongoing development of microfluidic techniques and their integration with protein production, characterization, and in situ diffraction promises to accelerate the progress of structural biology.

  10. Punch Card Programmable Microfluidics

    PubMed Central

    Korir, George; Prakash, Manu

    2015-01-01

    Small volume fluid handling in single and multiphase microfluidics provides a promising strategy for efficient bio-chemical assays, low-cost point-of-care diagnostics and new approaches to scientific discoveries. However multiple barriers exist towards low-cost field deployment of programmable microfluidics. Incorporating multiple pumps, mixers and discrete valve based control of nanoliter fluids and droplets in an integrated, programmable manner without additional required external components has remained elusive. Combining the idea of punch card programming with arbitrary fluid control, here we describe a self-contained, hand-crank powered, multiplex and robust programmable microfluidic platform. A paper tape encodes information as a series of punched holes. A mechanical reader/actuator reads these paper tapes and correspondingly executes operations onto a microfluidic chip coupled to the platform in a plug-and-play fashion. Enabled by the complexity of codes that can be represented by a series of holes in punched paper tapes, we demonstrate independent control of 15 on-chip pumps with enhanced mixing, normally-closed valves and a novel on-demand impact-based droplet generator. We demonstrate robustness of operation by encoding a string of characters representing the word “PUNCHCARD MICROFLUIDICS” using the droplet generator. Multiplexing is demonstrated by implementing an example colorimetric water quality assays for pH, ammonia, nitrite and nitrate content in different water samples. With its portable and robust design, low cost and ease-of-use, we envision punch card programmable microfluidics will bring complex control of microfluidic chips into field-based applications in low-resource settings and in the hands of children around the world. PMID:25738834

  11. Microfluidic platforms for mechanobiology

    PubMed Central

    Polacheck, William J.; Li, Ran; Uzel, Sebastien G. M.

    2013-01-01

    Mechanotransduction has been a topic of considerable interest since early studies demonstrated a link between mechanical force and biological response. Until recently, studies of fundamental phenomena were based either on in vivo experiments with limited control or direct access, or on large-scale in vitro studies lacking many of the potentially important physiological factors. With the advent of microfluidics, many of the previous limitations of in vitro testing were eliminated or reduced through greater control or combined functionalities. At the same time, imaging capabilities were tremendously enhanced. In this review, we discuss how microfluidics has transformed the study of mechanotransduction. This is done in the context of the various cell types that exhibit force-induced responses and the new biological insights that have been elucidated. We also discuss new microfluidic studies that could produce even more realistic models of in vivo conditions by combining multiple stimuli or creating a more realistic microenvironment. PMID:23649165

  12. Protein Microarrays with Novel Microfluidic Methods: Current Advances

    PubMed Central

    Dixit, Chandra K.; Aguirre, Gerson R.

    2014-01-01

    Microfluidic-based micromosaic technology has allowed the pattering of recognition elements in restricted micrometer scale areas with high precision. This controlled patterning enabled the development of highly multiplexed arrays multiple analyte detection. This arraying technology was first introduced in the beginning of 2001 and holds tremendous potential to revolutionize microarray development and analyte detection. Later, several microfluidic methods were developed for microarray application. In this review we discuss these novel methods and approaches which leverage the property of microfluidic technologies to significantly improve various physical aspects of microarray technology, such as enhanced imprinting homogeneity, stability of the immobilized biomolecules, decreasing assay times, and reduction of the costs and of the bulky instrumentation. PMID:27600343

  13. Blood coagulation screening using a paper-based microfluidic lateral flow device.

    PubMed

    Li, H; Han, D; Pauletti, G M; Steckl, A J

    2014-10-21

    A simple approach to the evaluation of blood coagulation using a microfluidic paper-based lateral flow assay (LFA) device for point-of-care (POC) and self-monitoring screening is reported. The device utilizes whole blood, without the need for prior separation of plasma from red blood cells (RBC). Experiments were performed using animal (rabbit) blood treated with trisodium citrate to prevent coagulation. CaCl2 solutions of varying concentrations are added to citrated blood, producing Ca(2+) ions to re-establish the coagulation cascade and mimic different blood coagulation abilities in vitro. Blood samples are dispensed into a paper-based LFA device consisting of sample pad, analytical membrane and wicking pad. The porous nature of the cellulose membrane separates the aqueous plasma component from the large blood cells. Since the viscosity of blood changes with its coagulation ability, the distance RBCs travel in the membrane in a given time can be related to the blood clotting time. The distance of the RBC front is found to decrease linearly with increasing CaCl2 concentration, with a travel rate decreasing from 3.25 mm min(-1) for no added CaCl2 to 2.2 mm min(-1) for 500 mM solution. Compared to conventional plasma clotting analyzers, the LFA device is much simpler and it provides a significantly larger linear range of measurement. Using the red colour of RBCs as a visible marker, this approach can be utilized to produce a simple and clear indicator of whether the blood condition is within the appropriate range for the patient's condition.

  14. Integrated separation of blood plasma from whole blood for microfluidic paper-based analytical devices.

    PubMed

    Yang, Xiaoxi; Forouzan, Omid; Brown, Theodore P; Shevkoplyas, Sergey S

    2012-01-21

    Many diagnostic tests in a conventional clinical laboratory are performed on blood plasma because changes in its composition often reflect the current status of pathological processes throughout the body. Recently, a significant research effort has been invested into the development of microfluidic paper-based analytical devices (μPADs) implementing these conventional laboratory tests for point-of-care diagnostics in resource-limited settings. This paper describes the use of red blood cell (RBC) agglutination for separating plasma from finger-prick volumes of whole blood directly in paper, and demonstrates the utility of this approach by integrating plasma separation and a colorimetric assay in a single μPAD. The μPAD was fabricated by printing its pattern onto chromatography paper with a solid ink (wax) printer and melting the ink to create hydrophobic barriers spanning through the entire thickness of the paper substrate. The μPAD was functionalized by spotting agglutinating antibodies onto the plasma separation zone in the center and the reagents of the colorimetric assay onto the test readout zones on the periphery of the device. To operate the μPAD, a drop of whole blood was placed directly onto the plasma separation zone of the device. RBCs in the whole blood sample agglutinated and remained in the central zone, while separated plasma wicked through the paper substrate into the test readout zones where analyte in plasma reacted with the reagents of the colorimetric assay to produce a visible color change. The color change was digitized with a portable scanner and converted to concentration values using a calibration curve. The purity and yield of separated plasma was sufficient for successful operation of the μPAD. This approach to plasma separation based on RBC agglutination will be particularly useful for designing fully integrated μPADs operating directly on small samples of whole blood.

  15. Use of multiple colorimetric indicators for paper-based microfluidic devices.

    PubMed

    Dungchai, Wijitar; Chailapakul, Orawon; Henry, Charles S

    2010-08-03

    We report here the use of multiple indicators for a single analyte for paper-based microfluidic devices (microPAD) in an effort to improve the ability to visually discriminate between analyte concentrations. In existing microPADs, a single dye system is used for the measurement of a single analyte. In our approach, devices are designed to simultaneously quantify analytes using multiple indicators for each analyte improving the accuracy of the assay. The use of multiple indicators for a single analyte allows for different indicator colors to be generated at different analyte concentration ranges as well as increasing the ability to better visually discriminate colors. The principle of our devices is based on the oxidation of indicators by hydrogen peroxide produced by oxidase enzymes specific for each analyte. Each indicator reacts at different peroxide concentrations and therefore analyte concentrations, giving an extended range of operation. To demonstrate the utility of our approach, the mixture of 4-aminoantipyrine and 3,5-dichloro-2-hydroxy-benzenesulfonic acid, o-dianisidine dihydrochloride, potassium iodide, acid black, and acid yellow were chosen as the indicators for simultaneous semi-quantitative measurement of glucose, lactate, and uric acid on a microPAD. Our approach was successfully applied to quantify glucose (0.5-20 mM), lactate (1-25 mM), and uric acid (0.1-7 mM) in clinically relevant ranges. The determination of glucose, lactate, and uric acid in control serum and urine samples was also performed to demonstrate the applicability of this device for biological sample analysis. Finally results for the multi-indicator and single indicator system were compared using untrained readers to demonstrate the improvements in accuracy achieved with the new system.

  16. Emergence of microfluidic wearable technologies.

    PubMed

    Yeo, Joo Chuan; Kenry; Lim, Chwee Teck

    2016-10-18

    There has been an intense interest in the development of wearable technologies, arising from increasing demands in the areas of fitness and healthcare. While still at an early stage, incorporating microfluidics in wearable technologies has enormous potential, especially in healthcare applications. For example, current microfluidic fabrication techniques can be innovatively modified to fabricate microstructures and incorporate electrically conductive elements on soft, flexible and stretchable materials. In fact, by leverarging on such microfabrication and liquid manipulation techniques, the developed flexible microfluidic wearable technologies have enabled several biosensing applications, including in situ sweat metabolites analysis, vital signs monitoring, and gait analysis. As such, we anticipate further significant breakthroughs and potential uses of wearable microfluidics in active drug delivery patches, soft robotics sensing and control, and even implantable artificial organs in the near future.

  17. Ciliated micropillars for the microfluidic-based isolation of nanoscale lipid vesicles.

    PubMed

    Wang, Zongxing; Wu, Hung-jen; Fine, Daniel; Schmulen, Jeffrey; Hu, Ye; Godin, Biana; Zhang, John X J; Liu, Xuewu

    2013-08-07

    We fabricated a microfluidic device consisting of ciliated micropillars, forming a porous silicon nanowire-on-micropillar structure. We demonstrated that the prototype device can preferentially trap exosome-like lipid vesicles, while simultaneously filtering out proteins and cell debris. Trapped lipid vesicles can be recovered intact by dissolving the porous nanowires in PBS buffer.

  18. Microfluidic rectifier based on poly(dimethylsiloxane) membrane and its application to a micropump.

    PubMed

    Wang, Yao-Nan; Tsai, Chien-Hsiung; Fu, Lung-Ming; Lin Liou, Lung-Kai

    2013-01-01

    A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2 m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200 μm and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump.

  19. Design, fabrication and characterization of nano-filters in silicon microfluidic channels based on MEMS technology.

    PubMed

    Chen, Xing; Cui, Dafu; Chen, Jian

    2009-09-01

    Since most clinical assays are performed on cell-free serum or plasma, micro-analytical systems for blood tests require integrated on-chip microfluidics for the isolation of plasma or serum from crude blood samples. In this paper, we present a crossflow filtration method using novel silicon nano-filters for plasma separation. The microfluidic chip is made of a silicon substrate containing micropillar arrays, feed channels, side channels and nano-gap structures, sealed with a PDMS-glass compound cover. The design of the silicon filtration structures were optimized using numerical analysis and the optimal MEMS fabrication procedures were obtained. The filtration structures including nano-filters were characterized using SEM and subsequently used to isolate plasma from whole blood in a continuous manner. Compared with micro-gap structures in silicon microfluidic channels, the nano-gap structures have been used to separate plasma from whole blood samples with higher selectivity, where a maximum plasma selectivity of 97.7% has been obtained. Common problems of clogging and jamming in filtration applications have seldom been noticed in our device. The presented microfluidic filtration device for plasma isolation could be integrated into microTAS for point-of-care diagnostics in the near future.

  20. Microfluidic point-of-care blood panel based on a novel technique: Reversible electroosmotic flow.

    PubMed

    Mohammadi, Mahdi; Madadi, Hojjat; Casals-Terré, Jasmina

    2015-09-01

    A wide range of diseases and conditions are monitored or diagnosed from blood plasma, but the ability to analyze a whole blood sample with the requirements for a point-of-care device, such as robustness, user-friendliness, and simple handling, remains unmet. Microfluidics technology offers the possibility not only to work fresh thumb-pricked whole blood but also to maximize the amount of the obtained plasma from the initial sample and therefore the possibility to implement multiple tests in a single cartridge. The microfluidic design presented in this paper is a combination of cross-flow filtration with a reversible electroosmotic flow that prevents clogging at the filter entrance and maximizes the amount of separated plasma. The main advantage of this design is its efficiency, since from a small amount of sample (a single droplet [Formula: see text]10 μl) almost 10% of this (approx 1 μl) is extracted and collected with high purity (more than 99%) in a reasonable time (5-8 min). To validate the quality and quantity of the separated plasma and to show its potential as a clinical tool, the microfluidic chip has been combined with lateral flow immunochromatography technology to perform a qualitative detection of the thyroid-stimulating hormone and a blood panel for measuring cardiac Troponin and Creatine Kinase MB. The results from the microfluidic system are comparable to previous commercial lateral flow assays that required more sample for implementing fewer tests.

  1. Microfluidic point-of-care blood panel based on a novel technique: Reversible electroosmotic flow

    PubMed Central

    Mohammadi, Mahdi; Madadi, Hojjat; Casals-Terré, Jasmina

    2015-01-01

    A wide range of diseases and conditions are monitored or diagnosed from blood plasma, but the ability to analyze a whole blood sample with the requirements for a point-of-care device, such as robustness, user-friendliness, and simple handling, remains unmet. Microfluidics technology offers the possibility not only to work fresh thumb-pricked whole blood but also to maximize the amount of the obtained plasma from the initial sample and therefore the possibility to implement multiple tests in a single cartridge. The microfluidic design presented in this paper is a combination of cross-flow filtration with a reversible electroosmotic flow that prevents clogging at the filter entrance and maximizes the amount of separated plasma. The main advantage of this design is its efficiency, since from a small amount of sample (a single droplet ∼10 μl) almost 10% of this (approx 1 μl) is extracted and collected with high purity (more than 99%) in a reasonable time (5–8 min). To validate the quality and quantity of the separated plasma and to show its potential as a clinical tool, the microfluidic chip has been combined with lateral flow immunochromatography technology to perform a qualitative detection of the thyroid-stimulating hormone and a blood panel for measuring cardiac Troponin and Creatine Kinase MB. The results from the microfluidic system are comparable to previous commercial lateral flow assays that required more sample for implementing fewer tests. PMID:26396660

  2. Microfluidic droplet-based PCR instrumentation for high-throughput gene expression profiling and biomarker discovery

    PubMed Central

    Hayes, Christopher J.; Dalton, Tara M.

    2015-01-01

    PCR is a common and often indispensable technique used in medical and biological research labs for a variety of applications. Real-time quantitative PCR (RT-qPCR) has become a definitive technique for quantitating differences in gene expression levels between samples. Yet, in spite of this importance, reliable methods to quantitate nucleic acid amounts in a higher throughput remain elusive. In the following paper, a unique design to quantify gene expression levels at the nanoscale in a continuous flow system is presented. Fully automated, high-throughput, low volume amplification of deoxynucleotides (DNA) in a droplet based microfluidic system is described. Unlike some conventional qPCR instrumentation that use integrated fluidic circuits or plate arrays, the instrument performs qPCR in a continuous, micro-droplet flowing process with droplet generation, distinctive reagent mixing, thermal cycling and optical detection platforms all combined on one complete instrument. Detailed experimental profiling of reactions of less than 300 nl total volume is achieved using the platform demonstrating the dynamic range to be 4 order logs and consistent instrument sensitivity. Furthermore, reduced pipetting steps by as much as 90% and a unique degree of hands-free automation makes the analytical possibilities for this instrumentation far reaching. In conclusion, a discussion of the first demonstrations of this approach to perform novel, continuous high-throughput biological screens is presented. The results generated from the instrument, when compared with commercial instrumentation, demonstrate the instrument reliability and robustness to carry out further studies of clinical significance with added throughput and economic benefits. PMID:27077035

  3. A large format membrane-based x-ray mask for microfluidic chip fabrication

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Zhang, Min; Desta, Yohannes; Melzak, J.; Wu, C. H.; Peng, Zhengchun

    2006-02-01

    X-ray lithography is a very good option for the fabrication of micro-devices especially when high aspect ratio patterns are required. Membrane-based x-ray masks are commonly used for high-resolution x-ray lithography. A thin layer of silicon nitride (Si3N4) or silicon carbide (SiC) film (1-2 µm) is normally used as the membrane material for x-ray mask fabrication (Wells G M, Reilly M, Nachman R, Cerrina F, El-Khakani M A and Chaker M 1993 Mater. Res. Soc. Conf. Proc. 306 81-9 Shoki T, Nagasawa H, Kosuga H, Yamaguchi Y, Annaka N, Amemiya I and Nagarekawa O 1993 SPIE Proc. 1924 450-6). The freestanding membrane window of an x-ray mask, which defines the exposing area of the x-ray mask, can be obtained by etching a pre-defined area on a silicon wafer from the backside (Wang L, Desta Y, Fettig R K, Goettert J, Hein H, Jakobs P and Chulz J 2004 J. Micromech. Microeng. 14 722-6). Usually, the window size of an x-ray mask is around 20 × 20 mm because of the low tensile stress of the membrane (10-100 MPa), and the larger window dimension of an x-ray mask may cause the deformation of membranes and lower the mask quality. However, x-ray masks with larger windows are preferred for micro-device fabrication in order to increase the productivity. We analyzed the factors which influence the flatness of large format x-ray masks and fabricated x-ray masks with a window size of 55 × 55 mm and 46 × 65 mm on 1 µm thick membranes by increasing the tensile stress of the membranes (>300 MPa) and optimizing the stress of the absorber layer. The large format x-ray mask was successfully applied for the fabrication of microfluidic chips.

  4. Polymer-based microfluidic chip for rapid and efficient immunomagnetic capture and release of Listeria monocytogenes.

    PubMed

    Malic, L; Zhang, X; Brassard, D; Clime, L; Daoud, J; Luebbert, C; Barrere, V; Boutin, A; Bidawid, S; Farber, J; Corneau, N; Veres, T

    2015-10-21

    Infections caused by foodborne pathogens such as Listeria monocytogenes pose a threat to public health while timely detection is challenging due to pathogen low numbers. The development of robust and efficient sample preparation techniques is crucial to improve detection sensitivity and workflow. Immunomagnetic separation using magnetic nanoparticles (MNPs) is attractive, as it can efficiently capture target cells. For food safety applications, a platform is needed to rapidly process large sample volumes, allowing capture and release of target bacteria conjugated to immunomagnetic nanoparticles (IMNPs). Herein, we demonstrate a method for magnetic capture and release of bacteria-IMNPs complex based on a 3D magnetic trap integrated on a polymeric microfluidic device. The 3D magnetic capture region consist of a dense array of high-aspect ratio (3 : 1) cylindrical pillars embossed in thermoplastic polymer and coated with soft ferromagnetic nickel by an electroless deposition technique. This allows the generation of strong and switchable magnetic capture regions due to the very low remanence of the nickel shell. We propose and validate an optimized configuration of capture regions for efficient localized capture and rapid release of MNPs and IMNPs conjugated to L. monocytogenes. A maximum recovery rate for MNPs corresponded to 91% while a maximum capture efficiency of 30% was obtained for live bacteria, with a minimum detectable sample concentration of ~10 cfu ml(-1) in 1 ml volume using plate-culture method. We believe that the flexible design and low-cost fabrication process of the proposed system will allow rapid sample preparation for applications beyond food and water safety, including point-of-care diagnosis.

  5. Chemistry in Microfluidic Channels

    ERIC Educational Resources Information Center

    Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

    2011-01-01

    General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

  6. Multiple enzyme-doped thread-based microfluidic system for blood urea nitrogen and glucose detection in human whole blood

    PubMed Central

    Yang, Yu-An

    2015-01-01

    This research presents a multiple enzyme-doped thread-based microfluidic system for blood urea nitrogen (BUN) and glucose detection in human whole blood. A novel enzyme-doped thread coated with a thin polyvinylchloride (PVC) membrane is produced for on-site electrochemical detection of urea and glucose in whole blood. Multiple enzymes can be directly applied to the thread without delicate pretreatment or a surface modification process prior to sealing the thread with PVC membrane. Results indicate that the developed device exhibits a good linear dynamic range for detecting urea and glucose in concentrations from 0.1 mM–10.0 mM (R2 = 0.9850) and 0.1 mM–13.0 mM (R2 = 0.9668), which is suitable for adoption in detecting the concentrations of blood urea nitrogen (BUN, 1.78–7.12 mM) and glucose (3.89–6.11 mM) in serum. The detection result also shows that the developed thread-based microfluidic system can successfully separate and detect the ions, BUN, and glucose in blood. The calculated concentrations of BUN and glucose ante cibum (glucose before meal) in the whole blood sample are 3.98 mM and 4.94 mM, respectively. The developed thread-based microfluidic system provides a simple yet high performance for clinical diagnostics. PMID:25825613

  7. Hydrodynamic and direct-current insulator-based dielectrophoresis (H-DC-iDEP) microfluidic blood plasma separation.

    PubMed

    Mohammadi, Mahdi; Madadi, Hojjat; Casals-Terré, Jasmina; Sellarès, Jordi

    2015-06-01

    Evaluation and diagnosis of blood alterations is a common request for clinical laboratories, requiring a complex technological approach and dedication of health resources. In this paper, we present a microfluidic device that owing to a novel combination of hydrodynamic and dielectrophoretic techniques can separate plasma from fresh blood in a microfluidic channel and for the first time allows optical real-time monitoring of the components of plasma without pre- or post-processing. The microchannel is based on a set of dead-end branches at each side and is initially filled using capillary forces with a 2-μL droplet of fresh blood. During this process, stagnation zones are generated at the dead-end branches and some red blood cells (RBCs) are trapped there. An electric field is then applied and dielectrophoretic trapping of RBCs is used to prevent more RBCs entering into the channel, which works like a sieve. Besides, an electroosmotic flow is generated to sweep the rest of the RBCs from the central part of the channel. Consequently, an RBC-free zone of plasma is formed in the middle of the channel, allowing real-time monitoring of the platelet behavior. To study the generation of stagnation zones and to ensure RBC trapping in the initial constrictions, two numerical models were solved. The proposed experimental design separates up to 0.1 μL blood plasma from a 2-μL fresh human blood droplet. In this study, a plasma purity of 99 % was achieved after 7 min, according to the measurements taken by image analysis. Graphical Abstract Schematics of a real-time plasma monitoring system based on a Hydrodynamic and direct-current insulator-based dielectrophoresis microfluidic channel.

  8. Optical systems for integration with microfluidics

    NASA Astrophysics Data System (ADS)

    Godin, Jessica M.

    My thesis research has focused on means of integrating optical systems into microfluidic chips, specifically for the creation of lab-on-a-chip flow cytometers. The benefits of microfluidics are perhaps most often applied to biological assays, which frequently employ optical readout of fluorescence or light scatter. By integrating the optical system onto the microfluidic chip, we can facilitate chip interfacing while ensuring optical alignment to a tiny sample. Integrated optical systems also offer the ability to collect light from a localized area, allowing for the collection of true angular light scatter (which carries much information about cells) and can furthermore significantly improve the signal to noise ratio (SNR) relative to simple fiber or waveguide based approaches to integrated light collection. This work explores both the unique challenges and advantages encountered when creating optical systems integrated with mold-replicated microfluidic devices. The first contribution presented is the demonstration of fluid-filled lenses integrated alongside microfluidic channels using a slab waveguiding structure. The use of fluid represents an important tradeoff between lens power and Fresnel reflections. The creation of a slab waveguiding structure is critically important to control light losses when utilizing lens systems for light collection. The second contribution in this work is the demonstration of a microfluidic chip emplying a number of lenses to perform both localized excitation of the samples as well as light collection from localized areas defined by a specific angular range. Sample coefficients of variation (CVs) ranged from 9-16% for a single bead population, far exceeding previously-published CVs of 25-35%. The last contribution is an atypical approach to optical systems based on the unique advantages offered by microfabricated architectures, namely small sizes and close proximities to the sample. Using only custom-shaped total internal reflection

  9. Towards microfluidic-based depletion of stiff and fragile human red cells that accumulate during blood storage

    PubMed Central

    Huang, Sha; Hou, Han Wei; Kanias, Tamir; Sertorio, JT; Chen, Huichao; Sinchar, Derek; Gladwin, Mark; Han, Jongyoon

    2014-01-01

    In this study, the effects of prolonged storage on several biophysical properties of red blood cells (RBCs) were investigated. Single cell deformability was used as an important criterion in determining subgroups of RBCs evolved during storage lesion. A deformability-based microfluidic cell sorting technology was applied, which demonstrates the ability to enrich and separate the less deformable subpopulations of stored blood. These less deformable RBC subpopulations were then associated with other important markers such as osmotic fragility indicating cell integrity as well as microparticle content. This work demonstrates a systematic methodology to both monitor and improve banked blood quality, thereby reducing risks related to blood transfusion. PMID:25406942

  10. Ultra-narrow width air-gap Si FET integrated with micro-fluidic delivery for charge based sensing

    NASA Astrophysics Data System (ADS)

    Gokirmak, Ali; Tiwari, Sandip

    2005-11-01

    An ultra-narrow width silicon field effect transistor (FET) with a suspended gate, integrated with on-chip microfluidic delivery system is described. The device is designed to be used as an FET based sensor for sequencing of DNA, RNA and proteins, by detecting the local charge variations along the chains of these molecules as they are passed between the gate and the channel of the FET in an aqueous solution. A side-gated FET structure is demonstrated with sub-10 nm width, successfully suppressing the electrical leakage currents at the device edges. Side-gated FET structure allows electrostatic confinement of the electrons in the channel for increased spatial resolution.

  11. Battery-triggered ultrasensitive electrochemiluminescence detection on microfluidic paper-based immunodevice based on dual-signal amplification strategy.

    PubMed

    Li, Weiping; Li, Meng; Ge, Shenguang; Yan, Mei; Huang, Jiadong; Yu, Jinghua

    2013-03-12

    Dual-signal amplification strategy for ultrasensitive electrochemiluminescence (ECL) multiplexed immunoassay on microfluidic paper-based analytical devices (μ-PADs) was demonstrated. This dual-signal amplification technique was achieved by employing graphene oxide-chitosan/gold nanoparticles (GCA) immunosensing platform and [4,4'-(2,5-dimethoxy-1,4-phenylene)bis(ethyne-2,1-diyl) dibenzoic acid] (P-acid) functionalized nanoporous silver (P-acid/NPS) signal amplification label. For further low-cost and disposable applications, battery-triggered constant-potential ECL (+1.0V for P-acid label (vs. Ag/AgCl auxiliary electrode)) was applied on this paper-based immunodevice with the aid of a home-made voltage-tunable power device, allowing the traditional electrochemical workstation to be abandoned. We found that two tumor markers could be sequentially detected in the linear ranges of 0.003-20 and 0.001-10ngmL(-1) with the detection limits down to 1.0 and 0.8pgmL(-1), respectively, by simply reversing the connection mode on two working electrodes. The results exhibited excellent precision and high sensitivity of such immunoassay, and it also demonstrated that this battery-triggered ECL paper-based immunodevice could provide a rapid, simple and simultaneous multiplex immunoassay with high throughput, low-cost and low detection limits for point-of-care testing.

  12. Multiplexed detection of DNA sequences using a competitive displacement assay in a microfluidic SERRS-based device.

    PubMed

    Yazdi, Soroush H; Giles, Kristen L; White, Ian M

    2013-11-05

    We demonstrate sensitive and multiplexed detection of DNA sequences through a surface enhanced resonance Raman spectroscopy (SERRS)-based competitive displacement assay in an integrated microsystem. The use of the competitive displacement scheme, in which the target DNA sequence displaces a Raman-labeled reporter sequence that has lower affinity for the immobilized probe, enables detection of unlabeled target DNA sequences with a simple single-step procedure. In our implementation, the displacement reaction occurs in a microporous packed column of silica beads prefunctionalized with probe-reporter pairs. The use of a functionalized packed-bead column in a microfluidic channel provides two major advantages: (i) immobilization surface chemistry can be performed as a batch process instead of on a chip-by-chip basis, and (ii) the microporous network eliminates the diffusion limitations of a typical biological assay, which increases the sensitivity. Packed silica beads are also leveraged to improve the SERRS detection of the Raman-labeled reporter. Following displacement, the reporter adsorbs onto aggregated silver nanoparticles in a microfluidic mixer; the nanoparticle-reporter conjugates are then trapped and concentrated in the silica bead matrix, which leads to a significant increase in plasmonic nanoparticles and adsorbed Raman reporters within the detection volume as compared to an open microfluidic channel. The experimental results reported here demonstrate detection down to 100 pM of the target DNA sequence, and the experiments are shown to be specific, repeatable, and quantitative. Furthermore, we illustrate the advantage of using SERRS by demonstrating multiplexed detection. The sensitivity of the assay, combined with the advantages of multiplexed detection and single-step operation with unlabeled target sequences makes this method attractive for practical applications. Importantly, while we illustrate DNA sequence detection, the SERRS-based competitive

  13. Microfluidic lab-on-a-foil for nucleic acid analysis based on isothermal recombinase polymerase amplification (RPA).

    PubMed

    Lutz, Sascha; Weber, Patrick; Focke, Max; Faltin, Bernd; Hoffmann, Jochen; Müller, Claas; Mark, Daniel; Roth, Günter; Munday, Peter; Armes, Niall; Piepenburg, Olaf; Zengerle, Roland; von Stetten, Felix

    2010-04-07

    For the first time we demonstrate a self-sufficient lab-on-a-foil system for the fully automated analysis of nucleic acids which is based on the recently available isothermal recombinase polymerase amplification (RPA). The system consists of a novel, foil-based centrifugal microfluidic cartridge including prestored liquid and dry reagents, and a commercially available centrifugal analyzer for incubation at 37 degrees C and real-time fluorescence detection. The system was characterized with an assay for the detection of the antibiotic resistance gene mecA of Staphylococcus aureus. The limit of detection was <10 copies and time-to-result was <20 min. Microfluidic unit operations comprise storage and release of liquid reagents, reconstitution of lyophilized reagents, aliquoting the sample into < or = 30 independent reaction cavities, and mixing of reagents with the DNA samples. The foil-based cartridge was produced by blow-molding and sealed with a self-adhesive tape. The demonstrated system excels existing PCR based lab-on-a-chip platforms in terms of energy efficiency and time-to-result. Applications are suggested in the field of mobile point-of-care analysis, B-detection, or in combination with continuous monitoring systems.

  14. Microfluidic toner-based analytical devices: disposable, lightweight, and portable platforms for point-of-care diagnostics with colorimetric detection.

    PubMed

    Oliveira, Karoliny Almeida; de Souza, Fabrício Ribeiro; de Oliveira, Cristina Rodrigues; da Silveira, Lucimeire Antonelli; Coltro, Wendell Karlos Tomazelli

    2015-01-01

    This chapter describes the development of microfluidic toner-based analytical devices (μTADs) to perform clinical diagnostics using a scanner or cell-phone camera. μTADs have been produced in a platform composed of polyester and toner by the direct-printing technology (DPT) in a matter of minutes. This technology offers simplicity and versatility, and it does not require any sophisticated instrumentation. Toner-based devices integrate the current generation of disposable analytical devices along paper-based chips. The cost of one μTAD has been estimated to be lower than $0.10. In addition, these platforms are lightweight and portable thus enabling their use for point-of-care applications. In the last 5 years, great efforts have been dedicated to spread out the use of μTADs in bioassays. The current chapter reports the fabrication of printed microplates and integrated microfluidic toner-based devices for dengue diagnostics and rapid colorimetric assays with clinically relevant analytes including cholesterol, triglycerides, total proteins, and glucose. The use of μTADs associated with cell-phone camera may contribute to the health care, in special, to people housed in developing regions or with limited access to clinics and hospitals.

  15. Biodegradable microfluidic scaffolds for tissue engineering from amino alcohol-based poly(ester amide) elastomers.

    PubMed

    Wang, Jane; Bettinger, Christopher J; Langer, Robert S; Borenstein, Jeffrey T

    2010-01-01

    Biodegradable polymers with high mechanical strength, flexibility and optical transparency, optimal degradation properties and biocompatibility are critical to the success of tissue engineered devices and drug delivery systems. Most biodegradable polymers suffer from a short half life due to rapid degradation upon implantation, exceedingly high stiffness, and limited ability to functionalize the surface with chemical moieties. This work describes the fabrication of microfluidic networks from poly(ester amide), poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS), a recently developed biodegradable elastomeric poly(ester amide). Microfluidic scaffolds constructed from APS exhibit a much lower Young's Modulus and a significantly longer degradation half-life than those of previously reported systems. The device is fabricated using a modified replica-molding technique, which is rapid, inexpensive, reproducible, and scalable, making the approach ideal for both rapid prototyping and manufacturing of tissue engineering scaffolds.

  16. Biodegradable microfluidic scaffolds for tissue engineering from amino alcohol-based poly(ester amide) elastomers

    PubMed Central

    Wang, Jane; Bettinger, Christopher J; Langer, Robert S

    2010-01-01

    Biodegradable polymers with high mechanical strength, flexibility and optical transparency, optimal degradation properties and biocompatibility are critical to the success of tissue engineered devices and drug delivery systems. Most biodegradable polymers suffer from a short half-life due to rapid degradation upon implantation, exceedingly high stiffness, and limited ability to functionalize the surface with chemical moieties. This work describes the fabrication of microfluidic networks from poly(ester amide), poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS), a recently developed biodegradable elastomeric polymer. Microfluidic scaffolds constructed from APS exhibit a much lower Young's modulus and a significantly longer degradation half-life than those of previously reported systems. The device is fabricated using a modified replica-molding technique, which is rapid, inexpensive, reproducible and scalable, making the approach ideal for both rapid prototyping and manufacturing of tissue engineering scaffolds. PMID:21220957

  17. Validation of a fully autonomous phosphate analyser based on a microfluidic lab-on-a-chip.

    PubMed

    Slater, C; Cleary, J; Lau, K-T; Snakenborg, D; Corcoran, B; Kutter, J P; Diamond, D

    2010-01-01

    This work describes the design of a phosphate analyser that utilises a microfluidic lab-on-a-chip. The analyser contains all the required chemical storage, pumping and electronic components to carry out a complete phosphate assay. The system is self-calibrating and self-cleaning, thus capable of long-term operation. This was proven by a bench top calibration of the analyser using standard solutions and also by comparing the analyser's performance to a commercially available phosphate monitor installed at a waste water treatment plant. The output of the microfluidic lab-on-a-chip analyser was shown to have sensitivity and linear range equivalent to the commercially available monitor and also the ability to operate over an extended period of time.

  18. Modular microfluidic cartridge-based universal diagnostic system for global health applications

    NASA Astrophysics Data System (ADS)

    Becker, Holger; Klemm, Richard; Dietze, William; White, Wallace; Hlawatsch, Nadine; Freyberg, Susanne; Moche, Christian; Dailey, Peter; Gärtner, Claudia

    2016-03-01

    Current microfluidics-enabled point-of-care diagnostic systems are typically designed specifically for one assay type, e.g. a molecular diagnostic assay for a single disease of a class of diseases. This approach often leads to high development cost and a significant training requirement for users of different instruments. We have developed an open platform diagnostic system which allows to run molecular, immunological and clinical assays on a single instrument platform with a standardized microfluidic cartridge architecture in an automated sample-in answer-out fashion. As examples, a molecular diagnostic assay for tuberculosis, an immunoassay for HIV p24 and a clinical chemistry assay for ALT liver function have been developed and results of their pre-clinical validation are presented.

  19. Microfluidics-Based in Vivo Mimetic Systems for the Study of Cellular Biology

    PubMed Central

    2015-01-01

    Conspectus The human body is a complex network of molecules, organelles, cells, tissues, and organs: an uncountable number of interactions and transformations interconnect all the system’s components. In addition to these biochemical components, biophysical components, such as pressure, flow, and morphology, and the location of all of these interactions play an important role in the human body. Technical difficulties have frequently limited researchers from observing cellular biology as it occurs within the human body, but some state-of-the-art analytical techniques have revealed distinct cellular behaviors that occur only in the context of the interactions. These types of findings have inspired bioanalytical chemists to provide new tools to better understand these cellular behaviors and interactions. What blocks us from understanding critical biological interactions in the human body? Conventional approaches are often too naïve to provide realistic data and in vivo whole animal studies give complex results that may or may not be relevant for humans. Microfluidics offers an opportunity to bridge these two extremes: while these studies will not model the complexity of the in vivo human system, they can control the complexity so researchers can examine critical factors of interest carefully and quantitatively. In addition, the use of human cells, such as cells isolated from donated blood, captures human-relevant data and limits the use of animals in research. In addition, researchers can adapt these systems easily and cost-effectively to a variety of high-end signal transduction mechanisms, facilitating high-throughput studies that are also spatially, temporally, or chemically resolved. These strengths should allow microfluidic platforms to reveal critical parameters in the human body and provide insights that will help with the translation of pharmacological advances to clinical trials. In this Account, we describe selected microfluidic innovations within the

  20. Microfluidics-based in vivo mimetic systems for the study of cellular biology.

    PubMed

    Kim, Donghyuk; Wu, Xiaojie; Young, Ashlyn T; Haynes, Christy L

    2014-04-15

    The human body is a complex network of molecules, organelles, cells, tissues, and organs: an uncountable number of interactions and transformations interconnect all the system's components. In addition to these biochemical components, biophysical components, such as pressure, flow, and morphology, and the location of all of these interactions play an important role in the human body. Technical difficulties have frequently limited researchers from observing cellular biology as it occurs within the human body, but some state-of-the-art analytical techniques have revealed distinct cellular behaviors that occur only in the context of the interactions. These types of findings have inspired bioanalytical chemists to provide new tools to better understand these cellular behaviors and interactions. What blocks us from understanding critical biological interactions in the human body? Conventional approaches are often too naïve to provide realistic data and in vivo whole animal studies give complex results that may or may not be relevant for humans. Microfluidics offers an opportunity to bridge these two extremes: while these studies will not model the complexity of the in vivo human system, they can control the complexity so researchers can examine critical factors of interest carefully and quantitatively. In addition, the use of human cells, such as cells isolated from donated blood, captures human-relevant data and limits the use of animals in research. In addition, researchers can adapt these systems easily and cost-effectively to a variety of high-end signal transduction mechanisms, facilitating high-throughput studies that are also spatially, temporally, or chemically resolved. These strengths should allow microfluidic platforms to reveal critical parameters in the human body and provide insights that will help with the translation of pharmacological advances to clinical trials. In this Account, we describe selected microfluidic innovations within the last 5 years

  1. Enhancing protease activity assay in droplet-based microfluidics using a biomolecule concentrator.

    PubMed

    Chen, Chia-Hung; Sarkar, Aniruddh; Song, Yong-Ak; Miller, Miles A; Kim, Sung Jae; Griffith, Linda G; Lauffenburger, Douglas A; Han, Jongyoon

    2011-07-13

    We introduce an integrated microfluidic device consisting of a biomolecule concentrator and a microdroplet generator, which enhances the limited sensitivity of low-abundance enzyme assays by concentrating biomolecules before encapsulating them into droplet microreactors. We used this platform to detect ultralow levels of matrix metalloproteinases (MMPs) from diluted cellular supernatant and showed that it significantly (~10-fold) reduced the time required to complete the assay and the sample volume used.

  2. Gel-based optical waveguides with live cell encapsulation and integrated microfluidics.

    PubMed

    Jain, Aadhar; Yang, Allen H J; Erickson, David

    2012-05-01

    In this Letter, we demonstrate a biocompatible microscale optical device fabricated from agarose hydrogel that allows for encapsulation of cells inside an optical waveguide. This allows for better interaction between the light in the waveguide and biology, since it can interact with the direct optical mode rather than the evanescent field. We characterize the optical properties of the waveguide and further incorporate a microfluidic channel over the optical structure, thus developing an integrated optofluidic system fabricated entirely from agarose gel.

  3. A microfluidics-based technique for automated and rapid labeling of cells for flow cytometry

    NASA Astrophysics Data System (ADS)

    Patibandla, Phani K.; Estrada, Rosendo; Kannan, Manasaa; Sethu, Palaniappan

    2014-03-01

    Flow cytometry is a powerful technique capable of simultaneous multi-parametric analysis of heterogeneous cell populations for research and clinical applications. In recent years, the flow cytometer has been miniaturized and made portable for application in clinical- and resource-limited settings. The sample preparation procedure, i.e. labeling of cells with antibodies conjugated to fluorescent labels, is a time consuming (˜45 min) and labor-intensive procedure. Microfluidics provides enabling technologies to accomplish rapid and automated sample preparation. Using an integrated microfluidic device consisting of a labeling and washing module, we demonstrate a new protocol that can eliminate sample handling and accomplish sample and reagent metering, high-efficiency mixing, labeling and washing in rapid automated fashion. The labeling module consists of a long microfluidic channel with an integrated chaotic mixer. Samples and reagents are precisely metered into this device to accomplish rapid and high-efficiency mixing. The mixed sample and reagents are collected in a holding syringe and held for up to 8 min following which the mixture is introduced into an inertial washing module to obtain ‘analysis-ready’ samples. The washing module consists of a high aspect ratio channel capable of focusing cells to equilibrium positions close to the channel walls. By introducing the cells and labeling reagents in a narrow stream at the center of the channel flanked on both sides by a wash buffer, the elution of cells into the wash buffer away from the free unbound antibodies is accomplished. After initial calibration experiments to determine appropriate ‘holding time’ to allow antibody binding, both modules were used in conjunction to label MOLT-3 cells (T lymphoblast cell line) with three different antibodies simultaneously. Results confirm no significant difference in mean fluorescence intensity values for all three antibodies labels (p < 0.01) between the

  4. Detecting bacteria and Determining Their Susceptibility to Antibiotics by Stochastic Confinement in Nanoliter Droplets using Plug-Based Microfluidics

    SciTech Connect

    Boedicker, J.; Li, L; Kline, T; Ismagilov, R

    2008-01-01

    This article describes plug-based microfluidic technology that enables rapid detection and drug susceptibility screening of bacteria in samples, including complex biological matrices, without pre-incubation. Unlike conventional bacterial culture and detection methods, which rely on incubation of a sample to increase the concentration of bacteria to detectable levels, this method confines individual bacteria into droplets nanoliters in volume. When single cells are confined into plugs of small volume such that the loading is less than one bacterium per plug, the detection time is proportional to plug volume. Confinement increases cell density and allows released molecules to accumulate around the cell, eliminating the pre-incubation step and reducing the time required to detect the bacteria. We refer to this approach as stochastic confinement. Using the microfluidic hybrid method, this technology was used to determine the antibiogram - or chart of antibiotic sensitivity - of methicillin-resistant Staphylococcus aureus (MRSA) to many antibiotics in a single experiment and to measure the minimal inhibitory concentration (MIC) of the drug cefoxitin (CFX) against this strain. In addition, this technology was used to distinguish between sensitive and resistant strains of S. aureus in samples of human blood plasma. High-throughput microfluidic techniques combined with single-cell measurements also enable multiple tests to be performed simultaneously on a single sample containing bacteria. This technology may provide a method of rapid and effective patient-specific treatment of bacterial infections and could be extended to a variety of applications that require multiple functional tests of bacterial samples on reduced timescales.

  5. Detecting bacteria and determining their susceptibility to antibiotics by stochastic confinement in nanoliter droplets using plug-based microfluidics.

    PubMed

    Boedicker, James Q; Li, Liang; Kline, Timothy R; Ismagilov, Rustem F

    2008-08-01

    This article describes plug-based microfluidic technology that enables rapid detection and drug susceptibility screening of bacteria in samples, including complex biological matrices, without pre-incubation. Unlike conventional bacterial culture and detection methods, which rely on incubation of a sample to increase the concentration of bacteria to detectable levels, this method confines individual bacteria into droplets nanoliters in volume. When single cells are confined into plugs of small volume such that the loading is less than one bacterium per plug, the detection time is proportional to plug volume. Confinement increases cell density and allows released molecules to accumulate around the cell, eliminating the pre-incubation step and reducing the time required to detect the bacteria. We refer to this approach as 'stochastic confinement'. Using the microfluidic hybrid method, this technology was used to determine the antibiogram - or chart of antibiotic sensitivity - of methicillin-resistant Staphylococcus aureus (MRSA) to many antibiotics in a single experiment and to measure the minimal inhibitory concentration (MIC) of the drug cefoxitin (CFX) against this strain. In addition, this technology was used to distinguish between sensitive and resistant strains of S. aureus in samples of human blood plasma. High-throughput microfluidic techniques combined with single-cell measurements also enable multiple tests to be performed simultaneously on a single sample containing bacteria. This technology may provide a method of rapid and effective patient-specific treatment of bacterial infections and could be extended to a variety of applications that require multiple functional tests of bacterial samples on reduced timescales.

  6. Concurrent DNA Preconcentration and Separation in Bipolar Electrode-Based Microfluidic Device

    PubMed Central

    Song, Hongjun; Wang, Yi; Garson, Charles; Pant, Kapil

    2015-01-01

    This paper presents a bipolar electrode (BPE) device in a microfluidic dual-channel design for concurrent preconcentration and separation of composite DNA containing samples. The novelty of the present effort relies on the combination of BPE-induced ion concentration polarization (ICP) and end-labeled free-solution electrophoresis (ELFSE). The ion concentration polarization effect arising from the faradaic reaction on the BPE is utilized to exert opposing electrophoretic and electroosmotic forces on the DNA samples. Meanwhile, end-labeled free-solution electrophoresis alters the mass-charge ratio to enable simultaneous DNA separation in free solution. The microfluidic device was fabricated using standard and soft lithography techniques to form gold-on-glass electrode capped with a PDMS microfluidic channel. Experimental testing with various DNA samples was carried out over a range of applied electric field. Concentration ratios up to 285× within 5 minutes for a 102-mer DNA, and concurrent preconcentration and free-solution separation of binary mixture of free and bound 102-mer DNA within 6 minutes was demonstrated. The effect of applied electric field was also interrogated with respect to pertinent performance metrics of preconcentration and separation. PMID:26005497

  7. Windowless microfluidic platform based on capillary burst valves for high intensity x-ray measurements

    SciTech Connect

    Vig, Asger Laurberg; Enevoldsen, Nikolaj; Thilsted, Anil Haraksingh; Eriksen, Johan; Kristensen, Anders; Haldrup, Kristoffer; Feidenhans'l, Robert; Nielsen, Martin Meedom

    2009-11-15

    We propose and describe a microfluidic system for high intensity x-ray measurements. The required open access to a microfluidic channel is provided by an out-of-plane capillary burst valve (CBV). The functionality of the out-of-plane CBV is characterized with respect to the diameter of the windowless access hole, ranging from 10 to 130 {mu}m. Maximum driving pressures from 22 to 280 mbar corresponding to refresh rates of the exposed sample from 300 Hz to 54 kHz is demonstrated. The microfluidic system is tested at beamline ID09b at the ESRF synchrotron radiation facility in Grenoble, and x-ray scattering measurements are shown to be feasible and to require only very limited amounts of sample, <1 ml/h of measurements without recapturing of sample. With small adjustments of the present chip design, scattering angles up to 30 deg. can be achieved without shadowing effects and integration on-chip mixing and spectroscopy appears straightforward.

  8. Rapid Detection of Food Allergens by Microfluidics ELISA-Based Optical Sensor

    PubMed Central

    Weng, Xuan; Gaur, Gautam; Neethirajan, Suresh

    2016-01-01

    The risks associated with the presence of hidden allergens in food have increased the need for rapid, sensitive, and reliable methods for tracing food allergens in commodities. Conventional enzyme immunosorbent assay (ELISA) has usually been performed in a centralized lab, requiring considerable time and sample/reagent consumption and expensive detection instruments. In this study, a microfluidic ELISA platform combined with a custom-designed optical sensor was developed for the quantitative analysis of the proteins wheat gluten and Ara h 1. The developed microfluidic ELISA biosensor reduced the total assay time from hours (up to 3.5 h) to 15–20 min and decreased sample/reagent consumption to 5–10 μL, compared to a few hundred microliters in commercial ELISA kits, with superior sensitivity. The quantitative capability of the presented biosensor is a distinctive advantage over the commercially available rapid methods such as lateral flow devices (LFD) and dipstick tests. The developed microfluidic biosensor demonstrates the potential for sensitive and less-expensive on-site determination for rapidly detecting food allergens in a complex sample system. PMID:27338488

  9. Microfluidic based high throughput synthesis of lipid-polymer hybrid nanoparticles with tunable diameters

    PubMed Central

    Feng, Qiang; Zhang, Lu; Liu, Chao; Li, Xuanyu; Hu, Guoqing; Sun, Jiashu; Jiang, Xingyu

    2015-01-01

    Core-shell hybrid nanoparticles (NPs) for drug delivery have attracted numerous attentions due to their enhanced therapeutic efficacy and good biocompatibility. In this work, we fabricate a two-stage microfluidic chip to implement a high-throughput, one-step, and size-tunable synthesis of mono-disperse lipid-poly (lactic-co-glycolic acid) NPs. The size of hybrid NPs is tunable by varying the flow rates inside the two-stage microfluidic chip. To elucidate the mechanism of size-controllable generation of hybrid NPs, we observe the flow field in the microchannel with confocal microscope and perform the simulation by a numerical model. Both the experimental and numerical results indicate an enhanced mixing effect at high flow rate, thus resulting in the assembly of small and mono-disperse hybrid NPs. In vitro experiments show that the large hybrid NPs are more likely to be aggregated in serum and exhibit a lower cellular uptake efficacy than the small ones. This microfluidic chip shows great promise as a robust platform for optimization of nano drug delivery system. PMID:26180574

  10. Hybrid microfluidic fuel cell based on Laccase/C and AuAg/C electrodes.

    PubMed

    López-González, B; Dector, A; Cuevas-Muñiz, F M; Arjona, N; Cruz-Madrid, C; Arana-Cuenca, A; Guerra-Balcázar, M; Arriaga, L G; Ledesma-García, J

    2014-12-15

    A hybrid glucose microfluidic fuel cell composed of an enzymatic cathode (Laccase/ABTS/C) and an inorganic anode (AuAg/C) was developed and tested. The enzymatic cathode was prepared by adsorption of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and Laccase on Vulcan XC-72, which act as a redox mediator, enzymatic catalyst and support, respectively. The Laccase/ABTS/C composite was characterised by Fourier Transform Infrared (FTIR) Spectroscopy, streaming current measurements (Zeta potential) and cyclic voltammetry. The AuAg/C anode catalyst was characterised by Transmission electron microscopy (TEM) and cyclic voltammetry. The hybrid microfluidic fuel cell exhibited excellent performance with a maximum power density value (i.e., 0.45 mW cm(-2)) that is the highest reported to date. The cell also exhibited acceptable stability over the course of several days. In addition, a Mexican endemic Laccase was used as the biocathode electrode and evaluated in the hybrid microfluidic fuel cell generating 0.5 mW cm(-2) of maximum power density.

  11. Rapid Detection of Food Allergens by Microfluidics ELISA-Based Optical Sensor.

    PubMed

    Weng, Xuan; Gaur, Gautam; Neethirajan, Suresh

    2016-06-07

    The risks associated with the presence of hidden allergens in food have increased the need for rapid, sensitive, and reliable methods for tracing food allergens in commodities. Conventional enzyme immunosorbent assay (ELISA) has usually been performed in a centralized lab, requiring considerable time and sample/reagent consumption and expensive detection instruments. In this study, a microfluidic ELISA platform combined with a custom-designed optical sensor was developed for the quantitative analysis of the proteins wheat gluten and Ara h 1. The developed microfluidic ELISA biosensor reduced the total assay time from hours (up to 3.5 h) to 15-20 min and decreased sample/reagent consumption to 5-10 μL, compared to a few hundred microliters in commercial ELISA kits, with superior sensitivity. The quantitative capability of the presented biosensor is a distinctive advantage over the commercially available rapid methods such as lateral flow devices (LFD) and dipstick tests. The developed microfluidic biosensor demonstrates the potential for sensitive and less-expensive on-site determination for rapidly detecting food allergens in a complex sample system.

  12. Self-Powered Wireless Affinity-Based Biosensor Based on Integration of Paper-Based Microfluidics and Self-Assembled RFID Antennas.

    PubMed

    Yuan, Mingquan; Alocilja, Evangelyn C; Chakrabartty, Shantanu

    2016-08-01

    This paper presents a wireless, self-powered, affinity-based biosensor based on the integration of paper-based microfluidics with our previously reported method for self-assembling radio-frequency (RF) antennas. At the core of the proposed approach is a silver-enhancement technique that grows portions of a RF antenna in regions where target antigens hybridize with target specific affinity probes. The hybridization regions are defined by a network of nitrocellulose based microfluidic channels which implement a self-powered approach to sample the reagent and control its flow and mixing. The integration substrate for the biosensor has been constructed using polyethylene and the patterning of the antenna on the substrate has been achieved using a low-cost ink-jet printing technique. The substrate has been integrated with passive radio-frequency identification (RFID) tags to demonstrate that the resulting sensor-tag can be used for continuous monitoring in a food supply-chain where direct measurement of analytes is typically considered to be impractical. We validate the proof-of-concept operation of the proposed sensor-tag using IgG as a model analyte and using a 915 MHz Ultra-high-frequency (UHF) RFID tagging technology.

  13. Microfluidic Approaches for Protein Crystal Structure Analysis.

    PubMed

    Maeki, Masatoshi; Yamaguchi, Hiroshi; Tokeshi, Manabu; Miyazaki, Masaya

    2016-01-01

    This review summarizes two microfluidic-based protein crystallization methods, protein crystallization behavior in the microfluidic devices, and their applications for X-ray crystal structure analysis. Microfluidic devices provide many advantages for protein crystallography; they require small sample volumes, provide high-throughput screening, and allow control of the protein crystallization. A droplet-based protein crystallization method is a useful technique for high-throughput screening and the formation of a single crystal without any complicated device fabrication process. Well-based microfluidic platforms also enable effective protein crystallization. This review also summarizes the protein crystal growth behavior in microfluidic devices as, is known from viewpoints of theoretical and experimental approaches. Finally, we introduce applications of microfluidic devices for on-chip crystal structure analysis.

  14. Rapid and alternative fabrication method for microfluidic paper based analytical devices.

    PubMed

    Malekghasemi, Soheil; Kahveci, Enver; Duman, Memed

    2016-10-01

    A major application of microfluidic paper-based analytical devices (µPADs) includes the field of point-of-care (POC) diagnostics. It is important for POC diagnostics to possess properties such as ease-of-use and low cost. However, µPADs need multiple instruments and fabrication steps. In this study, two different chemicals (Hexamethyldisilazane and Tetra-ethylorthosilicate) were used, and three different methods (heating, plasma treatment, and microwave irradiation) were compared to develop µPADs. Additionally, an inkjet-printing technique was used for generating a hydrophilic channel and printing certain chemical agents on different regions of a modified filter paper. A rapid and effective fabrication method to develop µPADs within 10min was introduced using an inkjet-printing technique in conjunction with a microwave irradiation method. Environmental scanning electron microscope (ESEM) and x-ray photoelectron spectroscopy (XPS) were used for morphology characterization and determining the surface chemical compositions of the modified filter paper, respectively. Contact angle measurements were used to fulfill the hydrophobicity of the treated filter paper. The highest contact angle value (141°±1) was obtained using the microwave irradiation method over a period of 7min, when the filter paper was modified by TEOS. Furthermore, by using this method, the XPS results of TEOS-modified filter paper revealed Si2p (23%) and Si-O bounds (81.55%) indicating the presence of Si-O-Si bridges and Si(OEt) groups, respectively. The ESEM results revealed changes in the porous structures of the papers and decreases in the pore sizes. Washburn assay measurements tested the efficiency of the generated hydrophilic channels in which similar water penetration rates were observed in the TEOS-modified filter paper and unmodified (plain) filter paper. The validation of the developed µPADs was performed by utilizing the rapid urease test as a model test system. The detection limit of

  15. Microfluidic technology for molecular diagnostics.

    PubMed

    Robinson, Tom; Dittrich, Petra S

    2013-01-01

    Molecular diagnostics have helped to improve the lives of millions of patients worldwide by allowing clinicians to diagnose patients earlier as well as providing better ongoing therapies. Point-of-care (POC) testing can bring these laboratory-based techniques to the patient in a home setting or to remote settings in the developing world. However, despite substantial progress in the field, there still remain many challenges. Progress in molecular diagnostics has benefitted greatly from microfluidic technology. This chapter aims to summarise the more recent advances in microfluidic-based molecular diagnostics. Sections include an introduction to microfluidic technology, the challenges of molecular diagnostics, how microfluidic advances are working to solve these issues, some alternative design approaches, and detection within these systems.

  16. Bioanalysis in structured microfluidic systems.

    PubMed

    Ros, Alexandra; Hellmich, Wibke; Regtmeier, Jan; Duong, Thanh Tu; Anselmetti, Dario

    2006-07-01

    Microfluidic and lab-on-a-chip devices have attracted widespread interest in separation sciences and bioanalysis. Recent designs in microfluidic devices extend common separation concepts by exploiting new phenomena for molecular dynamics on a length scale of 10 mum and below, giving rise to novel manipulation tools and nonintuitive phenomena for microseparations. Here, we focus on three very recent developments for bioseparations based on tailored microfluidic systems: Single cell navigation, trapping and steering with subsequent on-chip lysis, protein separation and LIF detection (Section 3.1), then we report dielectrophoretic trapping and separation of large DNA fragments in structured microfluidic devices (Section 3.2). Finally, a paradoxial migration phenomenon based on thermal fluctuations, periodically arranged microchannels and a biased alternating current electric field is presented in Section 3.3.

  17. Droplet-based microfluidics for high-throughput screening of a metagenomic library for isolation of microbial enzymes.

    PubMed

    Hosokawa, Masahito; Hoshino, Yuri; Nishikawa, Yohei; Hirose, Tomotada; Yoon, Dong Hyun; Mori, Tetsushi; Sekiguchi, Tetsushi; Shoji, Shuichi; Takeyama, Haruko

    2015-05-15

    This paper proposes a high-throughput, function-based screening approach of a metagenomic library for isolating novel microbial enzymes by droplet-based microfluidics. We used gel microdroplets (GMDs) dispersed in oil as picoliter-volume reaction vessels for lipolytic enzyme by encapsulating cells in individual GMDs. Using this approach, we monitored the growth of individual cells encapsulated in GMDs and assessed the enzyme reaction activities at the level of an individual GMD. We then applied this method to screen lipolytic enzyme genes from the metagenomic library constructed from soil collected from a quercus serrate forest of Mount Tsukuba, Ibaraki, Japan. In the workflow presented in this study, metagenomic library clones were encapsulated in 100-pL GMDs with a fluorogenic reporter substrate. A total of 67,000 metagenomic library clones can be screened in only 24 h with reduced consumption of reagents (i.e., <10 μL). As a result, we identified a novel lipolytic enzyme, EstT1, belonging to the EstD2 family of esterases and containing a putative signal peptide, which facilitates enzyme export and catalyzation of substrates in the periplasm. Our study demonstrates the potential of microfluidic GMDs as an efficient tool for metagenomic library screening of industrially relevant enzymes with the potential of significantly reducing the cost and time factors involved in successful practical application of microbial enzymes.

  18. Microfluidics-based single-step preparation of injection-ready polymeric nanosystems for medical imaging and drug delivery

    NASA Astrophysics Data System (ADS)

    Liu, Kegang; Zhu, Zhen; Wang, Xueya; Gonçalves, Daniel; Zhang, Bei; Hierlemann, Andreas; Hunziker, Patrick

    2015-10-01

    Translation of therapeutic polymeric nanosystems to patients and industry requires simplified, reproducible and scalable methods for assembly and loading. A single-step in-line process based on nanocoprecipitation of oxazoline-siloxane block copolymers in flow-focusing poly(dimethylsiloxane) microfluidics was designed to manufacture injection-ready nanosystems. Nanosystem characteristics could be controlled by copolymer concentration, block length and chemistry, microchannel geometry, flow rate, aqueous/organic flow rate ratio and payload concentration. The well-tolerated nanosystems exhibited differential cell binding and payload delivery and could confer sensitivity to photodynamic therapy to HeLa cancer cells. Such injection-ready nanosystems carrying drugs, diagnostic or functional materials may facilitate translation to clinical application.Translation of therapeutic polymeric nanosystems to patients and industry requires simplified, reproducible and scalable methods for assembly and loading. A single-step in-line process based on nanocoprecipitation of oxazoline-siloxane block copolymers in flow-focusing poly(dimethylsiloxane) microfluidics was designed to manufacture injection-ready nanosystems. Nanosystem characteristics could be controlled by copolymer concentration, block length and chemistry, microchannel geometry, flow rate, aqueous/organic flow rate ratio and payload concentration. The well-tolerated nanosystems exhibited differential cell binding and payload delivery and could confer sensitivity to photodynamic therapy to HeLa cancer cells. Such injection-ready nanosystems carrying drugs, diagnostic or functional materials may facilitate translation to clinical application. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03543k

  19. Fabrication of an Amperometric Flow-Injection Microfluidic Biosensor Based on Laccase for In Situ Determination of Phenolic Compounds

    PubMed Central

    Gonzalez-Rivera, Juan C.; Osma, Johann F.

    2015-01-01

    We aim to develop an in situ microfluidic biosensor based on laccase from Trametes pubescens with flow-injection and amperometry as the transducer method. The enzyme was directly immobilized by potential step chronoamperometry, and the immobilization was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The electrode response by amperometry was probed using ABTS and syringaldazine. A shift of interfacial electron transfer resistance and the electron transfer rate constant from 18.1 kΩ to 3.9 MΩ and 4.6 × 10−2 cm s−1 to 2.1 × 10−4 cm s−1, respectively, evidenced that laccase was immobilized on the electrode by the proposed method. We established the optimum operating conditions of temperature (55°C), pH (4.5), injection flow rate (200 µL min−1), and applied potential (0.4 V). Finally, the microfluidic biosensor showed better lower limit of detection (0.149 µM) and sensitivity (0.2341 nA µM−1) for ABTS than previous laccase-based biosensors and the in situ operation capacity. PMID:26509166

  20. High-Throughput Single-Cell Labeling (Hi-SCL) for RNA-Seq Using Drop-Based Microfluidics.

    PubMed

    Rotem, Assaf; Ram, Oren; Shoresh, Noam; Sperling, Ralph A; Schnall-Levin, Michael; Zhang, Huidan; Basu, Anindita; Bernstein, Bradley E; Weitz, David A

    2015-01-01

    The importance of single-cell level data is increasingly appreciated, and significant advances in this direction have been made in recent years. Common to these technologies is the need to physically segregate individual cells into containers, such as wells or chambers of a micro-fluidics chip. High-throughput Single-Cell Labeling (Hi-SCL) in drops is a novel method that uses drop-based libraries of oligonucleotide barcodes to index individual cells in a population. The use of drops as containers, and a microfluidics platform to manipulate them en-masse, yields a highly scalable methodological framework. Once tagged, labeled molecules from different cells may be mixed without losing the cell-of-origin information. Here we demonstrate an application of the method for generating RNA-sequencing data for multiple individual cells within a population. Barcoded oligonucleotides are used to prime cDNA synthesis within drops. Barcoded cDNAs are then combined and subjected to second generation sequencing. The data are deconvoluted based on the barcodes, yielding single-cell mRNA expression data. In a proof-of-concept set of experiments we show that this method yields data comparable to other existing methods, but with unique potential for assaying very large numbers of cells.

  1. Fabrication and testing of a CoNiCu/Cu CPP-GMR nanowire-based microfluidic biosensor

    NASA Astrophysics Data System (ADS)

    Bellamkonda, Ramya; John, Tom; Mathew, Bobby; DeCoster, Mark; Hegab, Hisham; Davis, Despina

    2010-02-01

    Giant magneto resistance (GMR)-based microfluidic biosensors are used in applications involving the detection, analysis, enumeration and characterization of magnetic nano-particles attached to biological mediums such as antibodies and DNA. Here we introduce a novel multilayered CoNiCu/Cu nanowire GMR-based microfluidic biosensor. The current perpendicular to the plane of multilayers (CPP)-nanowires GMR was used as the core sensing material in the biosensor which responds to magnetic fields depending on the concentration and the flow velocity of bio-nano-magnetic fluids. The device was tested with different control solutions such as DI-water, mineral oil, phosphate buffered saline (PBS), ferrofluid, polystyrene superparamagnetic beads (PSB) and Dynabeads sheep anti-rabbit IgG. The nanowire array resistance decreased with an increase in the ferrofluid concentration, and a maximum 15.8% relative GMR was observed for the undiluted ferrofluid. The sensor was also responding differently to various ferrofluid flow rates. The GMR device showed variation in the output signal when the PSB and Dynabeads of different dilutions were pumped through it. When the tests were performed with pulsing potentials (150 mV and 200 mV), an increased GMR response was identified at higher voltages for PSB and Dynabeads sheep anti-rabbit IgG.

  2. Fabrication of an Amperometric Flow-Injection Microfluidic Biosensor Based on Laccase for In Situ Determination of Phenolic Compounds.

    PubMed

    Gonzalez-Rivera, Juan C; Osma, Johann F

    2015-01-01

    We aim to develop an in situ microfluidic biosensor based on laccase from Trametes pubescens with flow-injection and amperometry as the transducer method. The enzyme was directly immobilized by potential step chronoamperometry, and the immobilization was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The electrode response by amperometry was probed using ABTS and syringaldazine. A shift of interfacial electron transfer resistance and the electron transfer rate constant from 18.1 kΩ to 3.9 MΩ and 4.6 × 10(-2) cm s(-1) to 2.1 × 10(-4) cm s(-1), respectively, evidenced that laccase was immobilized on the electrode by the proposed method. We established the optimum operating conditions of temperature (55°C), pH (4.5), injection flow rate (200 µL min(-1)), and applied potential (0.4 V). Finally, the microfluidic biosensor showed better lower limit of detection (0.149 µM) and sensitivity (0.2341 nA µM(-1)) for ABTS than previous laccase-based biosensors and the in situ operation capacity.

  3. Transition elements based on transfinite interpolation

    NASA Technical Reports Server (NTRS)

    Odabas, Onur R.; Sarigul-Klijn, Nesrin

    1993-01-01

    In this study the transfinite interpolation methodology, a 'blending-function' method in particular, is utilized for the formulation of transition elements. The method offers a formal way of meeting continuity requirements in a transition element. Element shape functions are derived by blending the continuity requirements of individual boundary segments. The blending directions are naturally orthogonal in rectangular domains therefore interpolation of the boundaries over rectangular 2D and 3D elements can be performed with minimal effort. In triangular domains, however, the choice of blending directions and interpolants is not straightforward. For that reason, two interpolation techniques are proposed for blending of the boundaries of triangular domains. A series of transition elements of various classes compatible with elements of different orders and dimensions is developed and the full potential of the transfinite interpolation, as it applies to element formulation, is explored.

  4. Microfluidic Device

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Lin, Jeffrey Chun-Hui (Inventor); Kasdan, Harvey L. (Inventor)

    2017-01-01

    Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

  5. Microfluidic Device

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Lin, Jeffrey Chun-Hui (Inventor); Kasdan, Harvey (Inventor)

    2015-01-01

    Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

  6. Microfluidic Device

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Lin, Jeffrey Chun-Hui (Inventor); Kasdan, Harvey L. (Inventor)

    2016-01-01

    Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

  7. Using droplet-based microfluidics to improve the catalytic properties of RNA under multiple-turnover conditions.

    PubMed

    Ryckelynck, Michael; Baudrey, Stéphanie; Rick, Christian; Marin, Annick; Coldren, Faith; Westhof, Eric; Griffiths, Andrew D

    2015-03-01

    In vitro evolution methodologies are powerful approaches to identify RNA with new functionalities. While Systematic Evolution of Ligands by Exponential enrichment (SELEX) is an efficient approach to generate new RNA aptamers, it is less suited for the isolation of efficient ribozymes as it does not select directly for the catalysis. In vitro compartmentalization (IVC) in aqueous droplets in emulsions allows catalytic RNAs to be selected under multiple-turnover conditions but suffers severe limitations that can be overcome using the droplet-based microfluidics workflow described in this paper. Using microfluidics, millions of genes in a library can be individually compartmentalized in highly monodisperse aqueous droplets and serial operations performed on them. This allows the different steps of the evolution process (gene amplification, transcription, and phenotypic assay) to be uncoupled, making the method highly flexible, applicable to the selection and evolution of a variety of RNAs, and easily adaptable for evolution of DNA or proteins. To demonstrate the method, we performed cycles of random mutagenesis and selection to evolve the X-motif, a ribozyme which, like many ribozymes selected using SELEX, has limited multiple-turnover activity. This led to the selection of variants, likely to be the optimal ribozymes that can be generated using point mutagenesis alone, with a turnover number under multiple-turnover conditions, k(ss) cat, ∼ 28-fold higher than the original X-motif, primarily due to an increase in the rate of product release, the rate-limiting step in the multiple-turnover reaction.

  8. Microfluidic Approaches to Synchrotron Radiation-Based Fourier Transform Infrared (SR-FTIR) Spectral Microscopy of Living Biosystems

    PubMed Central

    Loutherback, Kevin; Birarda, Giovanni; Chen, Liang; Holman, Hoi-Ying N.

    2016-01-01

    A long-standing desire in biological and biomedical sciences is to be able to probe cellular chemistry as biological processes are happening inside living cells. Synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectral microscopy is a label-free and nondestructive analytical technique that can provide spatiotemporal distributions and relative abundances of biomolecules of a specimen by their characteristic vibrational modes. Despite great progress in recent years, SR-FTIR imaging of living biological systems remains challenging because of the demanding requirements on environmental control and strong infrared absorption of water. To meet this challenge, microfluidic devices have emerged as a method to control the water thickness while providing a hospitable environment to measure cellular processes and responses over many hours or days. This paper will provide an overview of microfluidic device development for SR-FTIR imaging of living biological systems, provide contrast between the various techniques including closed and open-channel designs, and discuss future directions of development within this area. Even as the fundamental science and technological demonstrations develop, other ongoing issues must be addressed; for example, choosing applications whose experimental requirements closely match device capabilities, and developing strategies to efficiently complete the cycle of development. These will require imagination, ingenuity and collaboration. PMID:26732243

  9. Fabrication of poly(dimethylsiloxane) microfluidic system based on masters directly printed with an office laser printer.

    PubMed

    Bao, Ning; Zhang, Qing; Xu, Jing-Juan; Chen, Hong-Yuan

    2005-09-30

    Applications of poly(dimethylsiloxane) (PDMS)-based microfluidic systems are more popular nowadays. Previous fabrication methods of the masters for PDMS microchannels require complicated steps and/or special device. In this paper, we demonstrated that the toner printed on the transparency film with the office laser printer (1200 dpi) can be used as the positive relief of the masters. The transparency film was printed in two steps in order to obtain the same printing quality for the crossed lines. With the laser-printed master, the depth of the fabricated PDMS microchannels was ca. 10 microm and the smallest width was ca. 60 microm. Surface characteristics of the PDMS/PDMS microchannels were performed with SEM. Their electrokinetic properties were investigated by the aids of the measurement of electroosmotic flow (EOF) and the Ohm's curve. Using the PDMS/PDMS microchip CE systems, electroactive biological molecules and non-electroactive inorganic ions were well separated, respectively. This simple approach could make it easy to carry out the studies of PDMS microfluidic systems in more general labs without special devices.

  10. Entropy-based measures of in vivo cilia-driven microfluidic mixing derived from quantitative optical imaging

    NASA Astrophysics Data System (ADS)

    Chandrasekera, Kenny; Jonas, Stephan; Bhattacharya, Dipankan; Khokha, Mustafa; Choma, Michael A.

    2012-02-01

    Motile cilia are cellular organelles that project from different epithelial surfaces including respiratory epithelium. They generate directional fluid flow that removes harmful pathogens and particulate matter from the respiratory system. While it has been known that primary ciliary dyskinesia increases the risk of recurrent pulmonary infections, there is now heightened interest in understanding the role that cilia play in a wide-variety of respiratory diseases. Different optical imaging technologies are being investigated to visualize cilia-driven fluid flow, and quantitative image analysis is used to generate measures of ciliary performance. Here, we demonstrate the quantification of in vivo cilia-driven microfluidic mixing using spatial and temporal measures of Shannon information entropy. Using videomicroscopy, we imaged in vivo cilia-driven fluid flow generated by the epidermis of the Xenopus tropicalis embryo. Flow was seeded with either dyes or microparticles. Both spatial and temporal measures of entropy show significant levels of mixing, with maximum entropy measures of ~6.5 (out of a possible range of 0 to 8). Spatial entropy measures showed localization of mixing "hot-spots" and "cold-spots" and temporal measures showed mixing throughout.In sum, entropy-based measures of microfluidic mixing can characterize in vivo cilia-driven fluid flow and hold the potential for better characterization of ciliary dysfunction.

  11. Hydrodynamic and electrical considerations in the design of a four-electrode impedance-based microfluidic device.

    PubMed

    Justin, Gusphyl; Nasir, Mansoor; Ligler, Frances S

    2011-05-01

    A four-electrode impedance-based microfluidic device has been designed with tunable sensitivity for future applications to the detection of pathogens and functionalized microparticles specifically bound to molecular recognition molecules on the surface of a microfluidic channel. In order to achieve tunable sensitivity, hydrodynamic focusing was employed to confine the electric current by simultaneous introduction of two fluids (high- and low-conductivity solutions) into a microchannel at variable flow-rate ratios. By increasing the volumetric flow rate of the low-conductivity solution (sheath fluid) relative to the high-conductivity solution (sample fluid), increased focusing of the high-conductivity solution over four coplanar electrodes was achieved, thereby confining the current during impedance interrogation. The hydrodynamic and electrical properties of the device were analyzed for optimization and to resolve issues that would impact sensitivity and reproducibility in subsequent biosensor applications. These include variability in the relative flow rates of the sheath and sample fluids, changes in microchannel dimensions, and ionic concentration of the sample fluid. A comparative analysis of impedance measurements using four-electrode versus two-electrode configurations for impedance measurements also highlighted the advantages of using four electrodes for portable sensor applications.

  12. Using droplet-based microfluidics to improve the catalytic properties of RNA under multiple-turnover conditions

    PubMed Central

    Baudrey, Stéphanie; Rick, Christian; Marin, Annick; Coldren, Faith; Westhof, Eric

    2015-01-01

    In vitro evolution methodologies are powerful approaches to identify RNA with new functionalities. While Systematic Evolution of Ligands by Exponential enrichment (SELEX) is an efficient approach to generate new RNA aptamers, it is less suited for the isolation of efficient ribozymes as it does not select directly for the catalysis. In vitro compartmentalization (IVC) in aqueous droplets in emulsions allows catalytic RNAs to be selected under multiple-turnover conditions but suffers severe limitations that can be overcome using the droplet-based microfluidics workflow described in this paper. Using microfluidics, millions of genes in a library can be individually compartmentalized in highly monodisperse aqueous droplets and serial operations performed on them. This allows the different steps of the evolution process (gene amplification, transcription, and phenotypic assay) to be uncoupled, making the method highly flexible, applicable to the selection and evolution of a variety of RNAs, and easily adaptable for evolution of DNA or proteins. To demonstrate the method, we performed cycles of random mutagenesis and selection to evolve the X-motif, a ribozyme which, like many ribozymes selected using SELEX, has limited multiple-turnover activity. This led to the selection of variants, likely to be the optimal ribozymes that can be generated using point mutagenesis alone, with a turnover number under multiple-turnover conditions, ksscat, ∼28-fold higher than the original X-motif, primarily due to an increase in the rate of product release, the rate-limiting step in the multiple-turnover reaction. PMID:25605963

  13. Ultrahigh-throughput approach for analyzing single-cell genomic damage with an agarose-based microfluidic comet array.

    PubMed

    Li, Yiwei; Feng, Xiaojun; Du, Wei; Li, Ying; Liu, Bi-Feng

    2013-04-16

    Genomic DNA damage was generally identified with a "comet assay" but limited by low throughput and poor reproducibility. Here we demonstrated an ultrahigh-throughput approach with a microfluidic chip to simultaneously interrogate DNA damage conditions of up to 10,000 individual cells (approximately 100-fold in throughput over the conventional method) with better reproducibility. For experiment, agarose was chosen as the chip fabrication material, which would further act as an electrophoretic sieving matrix for DNA fragments separation. Cancer cells (HeLa or HepG2) were lined up in parallel microchannels by capillary effect to form a dense array of single cells. After treatment with different doses of hydrogen peroxide, individual cells were then lysed for subsequent single-cell gel electrophoresis in the direction vertical to microchannel and fluorescence detection. Through morphological analysis and fluorescent measurement of comet-shaped DNA, the damage conditions of individual cells could be quantified. DNA repair capacity was further evaluated to validate the reliability of this method. It indicated that the agarose-based microfluidic comet array electrophoresis was simple, highly reproducible, and of high throughput, providing a new method for highly efficient single-cell genomic analysis.

  14. Image analysis for a microfluidic paper-based analytical device using the CIE L*a*b* color system.

    PubMed

    Komatsu, Takeshi; Mohammadi, Saeed; Busa, Lori Shayne Alamo; Maeki, Masatoshi; Ishida, Akihiko; Tani, Hirofumi; Tokeshi, Manabu

    2016-11-28

    The combination of a microfluidic paper-based analytical device (μPAD) and digital image analysis is widely used for quantitative analysis with μPADs because of its easy and simple operation. Herein, we have demonstrated a quantitative analysis based on multiple color changes on a μPAD. The CIE L*a*b* color system was employed to analyse the digital images obtained with the μPAD. We made pH measurements using a universal pH-indicator showing multiple color changes for various pH values of aqueous test solutions. The detectable pH range of this method was wider than the typical grayscale-based image analysis, and we succeeded in the measurements for a wide pH range of 2-9.

  15. A microfluidic D-subminiature connector.

    PubMed

    Scott, Adina; Au, Anthony K; Vinckenbosch, Elise; Folch, Albert

    2013-06-07

    Standardized, affordable, user-friendly world-to-chip interfaces represent one of the major barriers to the adoption of microfluidics. We present a connector system for plug-and-play interfacing of microfluidic devices to multiple input and output lines. The male connectors are based on existing standardized housings from electronics that are inexpensive and widely available. The female connectors are fabricated using familiar replica molding techniques that can easily be adopted by microfluidic developers.

  16. Thermally conductive porous element-based recuperators

    NASA Technical Reports Server (NTRS)

    Du, Jian Hua (Inventor); Chow, Louis C (Inventor); Lin, Yeong-Ren (Inventor); Wu, Wei (Inventor); Kapat, Jayanta (Inventor); Notardonato, William U. (Inventor)

    2012-01-01

    A heat exchanger includes at least one hot fluid flow channel comprising a first plurality of open cell porous elements having first gaps there between for flowing a hot fluid in a flow direction and at least one cold fluid flow channel comprising a second plurality of open cell porous elements having second gaps therebetween for flowing a cold fluid in a countercurrent flow direction relative to the flow direction. The thermal conductivity of the porous elements is at least 10 W/mK. A separation member is interposed between the hot and cold flow channels for isolating flow paths associated these flow channels. The first and second plurality of porous elements at least partially overlap one another to form a plurality of heat transfer pairs which transfer heat from respective ones of the first porous elements to respective ones of the second porous elements through the separation member.

  17. Smart portable electrophoresis instrument based on multipurpose microfluidic chips with electrochemical detection.

    PubMed

    Fernández-la-Villa, Ana; Sánchez-Barragán, Dámaso; Pozo-Ayuso, Diego F; Castaño-Álvarez, Mario

    2012-09-01

    A second generation of a battery-powered portable electrophoresis instrument for the use of ME with electrochemical detection was developed. As the first-generation, the main unit of the instrument (150 mm × 165 mm × 95 mm) consists of four-outputs high-voltage power supply (HVPS) with maximum voltage of 3 KV and acquisition system (bipotentiostat) containing 2-channels for dual electrochemical detection. A new reusable microfluidic platform was designed in order to incorporate the microchips with the portable instrument. In this case, the platform is integrated to the main unit of the instrument so that it is not necessary to have any external cable for the interconnection of both parts, making the use of the complete system easier. The new platform contains all the electrical connections for the HVPS and bipotentiostat, as well as fluidic ports for driving the solutions. The microfluidic electrophoresis instrument is controlled by means of a user-friendly interface from a computer. The possibility of wireless connection (Bluetooth®) allows the use of the instrument without any external cable improving the portability. Therefore, the second generation brings a more compact and integrated electrophoresis instrument for "in situ" applications using microfluidic chips in an easy way. The performance of the electrophoresis system was initially evaluated using single- and dual-channel SU-8/Pyrex microchips with different models of integrated electrodes including microelectrodes and interdigitated arrays. The method was tested in different analytical applications such as separation of neurotransmitters, chlorophenols, purine derivatives, vitamins, polyphenolic acids, and flavones.

  18. Terahertz microfluidic sensor based on a parallel-plate waveguide resonant cavity

    NASA Astrophysics Data System (ADS)

    Mendis, Rajind; Astley, Victoria; Liu, Jingbo; Mittleman, Daniel M.

    2009-10-01

    We describe a terahertz optical resonator that is ideally suited for highly sensitive and noninvasive refractive-index monitoring. The resonator is formed by machining a rectangular groove into one plate of a parallel-plate waveguide, and is excited using the lowest-order transverse-electric (TE1) waveguide mode. Since the resonator can act as a channel for fluid flow, it can be easily integrated into a microfluidics platform for real-time monitoring. Using this resonator with only a few microliters of liquid, we demonstrate a refractive-index sensitivity of 3.7×105 nm/refractive-index-unit, the highest ever reported in any frequency range.

  19. A microfluidic device based on droplet storage for screening solubility diagrams.

    PubMed

    Laval, Philippe; Lisai, Nicolas; Salmon, Jean-Baptiste; Joanicot, Mathieu

    2007-07-01

    This work describes a new microfluidic device developed for the rapid screening of solubility diagrams. In several parallel channels, hundreds of nanolitre volume droplets of a given solution are first stored with a gradual variation in the solute concentration. Then, the application of a temperature gradient along these channels enables us to read directly and quantitatively phase diagrams, concentration vs. temperature. We show, using a solution of adipic acid, that we can measure ten points of the solubility curve in less than 1 hr and with only 250 microL of solution.

  20. A multilevel optical element based on the Fizeau multibeam interferometer

    NASA Astrophysics Data System (ADS)

    Zhmud', A. A.

    1990-10-01

    A new multilevel optical element is proposed which is based on the Fizeau multibeam interferometer and a single-frequency wavelength-tunable semiconductor injection lazer. Possible applications of the optical element in optical data processors are discussed. As an example, a high-speed 17-bit analog-digital converter based on this element is considered.

  1. Get to Understand More from Single-Cells: Current Studies of Microfluidic-Based Techniques for Single-Cell Analysis

    PubMed Central

    Lo, Shih-Jie; Yao, Da-Jeng

    2015-01-01

    This review describes the microfluidic techniques developed for the analysis of a single cell. The characteristics of microfluidic (e.g., little sample amount required, high-throughput performance) make this tool suitable to answer and to solve biological questions of interest about a single cell. This review aims to introduce microfluidic related techniques for the isolation, trapping and manipulation of a single cell. The major approaches for detection in single-cell analysis are introduced; the applications of single-cell analysis are then summarized. The review concludes with discussions of the future directions and opportunities of microfluidic systems applied in analysis of a single cell. PMID:26213918

  2. Active, Universal Particle Micromanipulators: CPUs for Microfluidics

    NASA Astrophysics Data System (ADS)

    Mezic, Igor; Bottausci, Frederic

    2007-11-01

    Current designs for Lab-on-a-Chip applications consist of a variety of separate microfluidic chambers and channels for functions such as concentration, separation, reaction and mixing of bioparticles in liquids. Here we advance an alternative concept, named μfCPU, the Microfluidic Central Processing Unit, where the key microfluidic operations are performed within a single enclosure, using software-based inputs rather than physical hardware changes, thus emulating the role of the Central Processing Unit in computers and cells in living organisms. We present an experimental embodiment of such a device and describe a variety of microfluidic manipulation tasks achieved in it by the use of a suite of electromotive and fluidic forces in a time-dependent way to produce on-demand functionality. We also discuss a new microfluidic devices architecture that utilizes μfCPU as the basic processing unit and uses centralized pumping instead of integrated microfluidic pumps.

  3. Development of a fully integrated analysis system for ions based on ion-selective optodes and centrifugal microfluidics

    NASA Technical Reports Server (NTRS)

    Johnson, R. D.; Badr, I. H.; Barrett, G.; Lai, S.; Lu, Y.; Madou, M. J.; Bachas, L. G.; Daunert, S. (Principal Investigator)

    2001-01-01

    A fully integrated, miniaturized analysis system for ions based on a centrifugal microfluidics platform and ion-selective optode membranes is described. The microfluidic architecture is composed of channels, five solution reservoirs, a measuring chamber, and a waste reservoir manufactured onto a disk-shaped substrate of poly(methyl methacrylate). Ion-selective optode membranes, composed of plasticized poly(vinyl chloride) impregnated with an ionophore, a proton chromoionophore, and a lipophilic anionic additive, were cast, with a spin-on device, onto a support layer and then immobilized on the disk. Fluid propulsion is achieved by the centrifugal force that results from spinning the disk, while a system of valves is built onto the disk to control flow. These valves operate based on fluid properties and fluid/substrate interactions and are controlled by the angular frequency of rotation. With this system, we have been able to deliver calibrant solutions, washing buffers, or "test" solutions to the measuring chamber where the optode membrane is located. An analysis system based on a potassium-selective optode has been characterized. Results indicate that optodes immobilized on the platform demonstrate theoretical responses in an absorbance mode of measurement. Samples of unknown concentration can be quantified to within 3% error by fitting the response function for a given optode membrane using an acid (for measuring the signal for a fully protonated chromoionophore), a base (for fully deprotonated chromoionophore), and two standard solutions. Further, the ability to measure ion concentrations by employing one standard solution in conjunction with acid and base and with two standards alone were studied to delineate whether the current architecture could be simplified. Finally, the efficacy of incorporating washing steps into the calibration protocol was investigated.

  4. Printing silicone-based hydrophobic barriers on paper for microfluidic assays using low-cost ink jet printers.

    PubMed

    Rajendra, Vinodh; Sicard, Clémence; Brennan, John D; Brook, Michael A

    2014-12-21

    Paper-based microfluidic devices exhibit many advantages for biological assays. Normally, the assays are restricted to certain areas of the paper by hydrophobic barriers comprised of wax or alkyl ketene dimers (AKD). Neither hydrophobic barrier is able to constrain aqueous solutions of surfactants, which are frequently used in biological assays. We demonstrate that rapidly curing silicone resins can be inkjet printed onto pure cellulose paper using inexpensive thermal ink-jet printers. The Piers-Rubinsztajn (PR) reaction dominates the cure chemistry leading to cellulose fibers that are surface coated with a silicone resin. The resulting barriers are able to resist penetration by surfactant solutions and even by the lower surface energy solvents DMF and DMSO. The utility of the barrier was demonstrated using a coliform assay based on detection of β-galactosidase.

  5. Microfluidic-based patterning of embryonic stem cells for in vitro development studies.

    PubMed

    Suri, Shalu; Singh, Ankur; Nguyen, Anh H; Bratt-Leal, Andres M; McDevitt, Todd C; Lu, Hang

    2013-12-07

    In vitro recapitulation of mammalian embryogenesis and examination of the emerging behaviours of embryonic structures require both the means to engineer complexity and accurately assess phenotypes of multicellular aggregates. Current approaches to study multicellular populations in 3D configurations are limited by the inability to create complex (i.e. spatially heterogeneous) environments in a reproducible manner with high fidelity thus impeding the ability to engineer microenvironments and combinations of cells with similar complexity to that found during morphogenic processes such as development, remodelling and wound healing. Here, we develop a multicellular embryoid body (EB) fusion technique as a higher-throughput in vitro tool, compared to a manual assembly, to generate developmentally relevant embryonic patterns. We describe the physical principles of the EB fusion microfluidic device design; we demonstrate that >60 conjoined EBs can be generated overnight and emulate a development process analogous to mouse gastrulation during early embryogenesis. Using temporal delivery of bone morphogenic protein 4 (BMP4) to embryoid bodies, we recapitulate embryonic day 6.5 (E6.5) during mouse embryo development with induced mesoderm differentiation in murine embryonic stem cells leading to expression of Brachyury-T-green fluorescent protein (T-GFP), an indicator of primitive streak development and mesoderm differentiation during gastrulation. The proposed microfluidic approach could be used to manipulate hundreds or more of individual embryonic cell aggregates in a rapid fashion, thereby allowing controlled differentiation patterns in fused multicellular assemblies to generate complex yet spatially controlled microenvironments.

  6. Migration distance-based platelet function analysis in a microfluidic system.

    PubMed

    Song, Suk-Heung; Lim, Chae-Seung; Shin, Sehyun

    2013-01-01

    Aggregation and adhesion of platelets to the vascular wall are shear-dependent processes that play critical roles in hemostasis and thrombosis at vascular injury sites. In this study, we designed a simple and rapid assay of platelet aggregation and adhesion in a microfluidic system. A shearing mechanism using a rotating stirrer provided adjustable shear rate and shearing time and induced platelet activation. When sheared blood was driven through the microchannel under vacuum pressure, shear-activated platelets adhered to a collagen-coated surface, causing blood flow to significantly slow and eventually stop. To measure platelet adhesion and aggregation, the migration distance (MD) of blood through the microchannel was monitored. As the microstirrer speed increased, MD initially decreased exponentially but then increased beyond a critical rpm. For platelet-excluded blood samples, there were no changes in MD with increasing stirrer speed. These findings imply that the stirrer provided sufficiently high shear to activate platelets and that blood MD is a potentially valuable index for measuring the shear-dependence of platelet activation. Our microfluidic system is quick and simple, while providing a precise assay to measure the effects of shear on platelet aggregation and adhesion.

  7. Microfluidics-based diagnostics of infectious diseases in the developing world.

    PubMed

    Chin, Curtis D; Laksanasopin, Tassaneewan; Cheung, Yuk Kee; Steinmiller, David; Linder, Vincent; Parsa, Hesam; Wang, Jennifer; Moore, Hannah; Rouse, Robert; Umviligihozo, Gisele; Karita, Etienne; Mwambarangwe, Lambert; Braunstein, Sarah L; van de Wijgert, Janneke; Sahabo, Ruben; Justman, Jessica E; El-Sadr, Wafaa; Sia, Samuel K

    2011-07-31

    One of the great challenges in science and engineering today is to develop technologies to improve the health of people in the poorest regions of the world. Here we integrated new procedures for manufacturing, fluid handling and signal detection in microfluidics into a single, easy-to-use point-of-care (POC) assay that faithfully replicates all steps of ELISA, at a lower total material cost. We performed this 'mChip' assay in Rwanda on hundreds of locally collected human samples. The chip had excellent performance in the diagnosis of HIV using only 1 μl of unprocessed whole blood and an ability to simultaneously diagnose HIV and syphilis with sensitivities and specificities that rival those of reference benchtop assays. Unlike most current rapid tests, the mChip test does not require user interpretation of the signal. Overall, we demonstrate an integrated strategy for miniaturizing complex laboratory assays using microfluidics and nanoparticles to enable POC diagnostics and early detection of infectious diseases in remote settings.

  8. A model microfluidics-based system for the human and mouse retina.

    PubMed

    Mishra, Shawn; Thakur, Ankush; Redenti, Stephen; Vazquez, Maribel

    2015-12-01

    The application of microfluidics technologies to the study of retinal function and response holds great promise for development of new and improved treatments for patients with degenerative retinal diseases. Restoration of vision via retinal transplantation therapy has been severely limited by the low numbers of motile cells observed post transplantation. Using modern soft lithographic techniques, we have developed the μRetina, a novel and convenient biomimetic microfluidics device capable of examing the migratory behavior of retinal lineage cells within biomimetic geometries of the human and mouse retina. Coupled computer simulations and experimental validations were used to characterize and confirm the formation of chemical concentration gradients within the μRetina, while real-time images within the device captured radial and theta cell migration in response to concentration gradients of stromal derived factor (SDF-1), a known chemoattractant. Our data underscore how the μRetina can be used to examine the concentration-dependent migration of retinal progenitors in order to enhance current therapies, as well as develop novel migration-targeted treatments.

  9. Highly efficient microfluidic sorting device for synchronizing developmental stages of C. elegans based on deflecting electrotaxis.

    PubMed

    Wang, Xixian; Hu, Rui; Ge, Anle; Hu, Liang; Wang, Shanshan; Feng, Xiaojun; Du, Wei; Liu, Bi-Feng

    2015-06-07

    C. elegans as a powerful model organism has been widely used in fundamental biological studies. Many of these studies frequently need a large number of different stage-synchronized worms due to the stage-specific features of C. elegans among 4 distinct larval stages and the adult stage. In this work, we present an interesting and cost-effective microfluidic approach to realize simultaneous sorting of C. elegans of different developmental stages by deflecting electrotaxis. The microfluidic device was fabricated using PDMS consisting of symmetric sorting channels with specific angles, which was further hybridized to an agarose plate. While applying an electric field, different stages of C. elegans would crawl to the negative pore with different angles due to their deflecting electrotaxis. Thus, the worms were separated and synchronized by stages. lon-2 mutant was further used to study this electrotactic response and the results indicated that the body size plays a key role in determining the deflecting angle in matured adult worms. In addition to discriminating wild-type hermaphrodites, it could also be employed to sort mutants with abnormal development sizes and males. Therefore, our device provided a versatile and highly efficient platform for sorting C. elegans to meet the requirement of large numbers of different stage-synchronized worms. It can also be further used to investigate the neuronal basis of deflecting electrotaxis in worms.

  10. High-throughput design of microfluidics based on directed bacterial motility.

    PubMed

    Kaehr, Bryan; Shear, Jason B

    2009-09-21

    Use of motile cells as sensors and actuators in microfabricated devices requires precise design of interfaces between living and non-living components, a process that has relied on slow revision of device architectures as prototypes are sequentially evaluated and re-designed. In this report, we describe a microdesign and fabrication approach capable of iteratively refining three-dimensional bacterial interfaces in periods as short as 10 minutes, and demonstrate its use to drive fluid transport by harnessing flagellar motion. In this approach, multiphoton excitation is used to promote protein photocrosslinking in a direct-write procedure mediated by static and dynamic masking, with the resultant microstructures serving to capture motile bacteria from the surrounding fluidic environment. Reproducible steering and patterning of flagellated E. coli cells drive microfluidic currents capable of guiding micro-objects on predictable trajectories with velocities reaching 150 microm s(-1) and achieving bulk flow through microchannels. We show that bacteria can be dynamically immobilized at specified positions, an approach that frees such devices from limitations imposed by the functional lifetime of cells. These results provide a foundation for the development of sophisticated microfluidic devices powered by cells.

  11. Droplet-based microfluidics platform for measurement of rapid erythrocyte water transport

    PubMed Central

    Jin, Byung-Ju; Esteva-Font, Cristina; Verkman, A.S.

    2015-01-01

    Cell membrane water permeability is an important determinant of epithelial fluid secretion, tissue swelling, angiogenesis, tumor spread and other biological processes. Cellular water channels, the aquaporins, are important drug targets. Water permeability is generally measured from the kinetics of cell volume change in response to an osmotic gradient. Here, we developed a microfluidics platform in which cells expressing a cytoplasmic, volume-sensing fluorescent dye are rapidly subjected to an osmotic gradient by solution mixing inside a ~ 0.1 nL droplet surrounded by oil. Solution mixing time was < 10 ms. Osmotic water permeability was deduced from a single, time-integrated fluorescence image of an observation area in which time after mixing is determined by spatial position. Water permeability was accurately measured in aquaporin-expressing erythrocytes with half-times for osmotic equilibration down to < 50 ms. Compared with conventional water permeability measurements using costly stopped-flow instrumentation, the microfluidics platform here utilizes sub-microliter blood sample volume, does not suffer from mixing artifact, and replaces challenging kinetic measurements by a single image capture using a standard laboratory fluorescence microscope. PMID:26159099

  12. A microfluidic device for antimicrobial susceptibility testing based on a broth dilution method.

    PubMed

    Lee, Wen-Bin; Fu, Chien-Yu; Chang, Wen-Hsin; You, Huey-Ling; Wang, Chih-Hung; Lee, Mel S; Lee, Gwo-Bin

    2017-01-15

    Bacterial resistance to antimicrobial compounds is increasing at a faster rate than the development of new antibiotics; this represents a critical challenge for clinicians worldwide. Normally, the minimum inhibitory concentration of an antibiotic, the dosage at which bacterial growth is thwarted, provides an effective quantitative measure for antimicrobial susceptibility testing, and determination of minimum inhibitory concentration is conventionally performed by either a serial broth dilution method or with the commercially available Etest(®) (Biomerieux, France) kit. However, these techniques are relatively labor-intensive and require a significant amount of training. In order to reduce human error and increase operation simplicity, a simple microfluidic device that can perform antimicrobial susceptibility testing automatically via a broth dilution method to accurately determine the minimum inhibitory concentration was developed herein. As a proof of concept, wild-type (ATCC 29212) and vancomycin-resistant Enterococcus cells were incubated at five different vancomycin concentrations on-chip, and the sample injection, transport, and mixing processes occurred within five reaction chambers and three reagent chambers via the chip's automatic dispensation and dilution functions within nine minutes. The minimum inhibitory concentration values measured after 24h of antibiotic incubation were similar to those calculated using Etest(®). With its high flexibility, reliability, and portability, the developed microfluidic device provides a simple method for antimicrobial susceptibility testing in an automated format that could be implemented for clinical and point-of-care applications.

  13. LabCD: a centrifuge-based microfluidic platform for diagnostics

    NASA Astrophysics Data System (ADS)

    Madou, Marc J.; Kellogg, Gregory J.

    1998-04-01

    Diagnostics for point-of-care (POC) and field use requires the integration of fluid processes with means of detection in a user-friendly, portable package. A drawback to the use of many current analyzers for POC and field applications is their reliance on expensive and fragile robotic technology for automation, lack of portability, and incomplete integration of sample processing into the device. As a result, a number of microfluidic technologies are being developed for diagnostics applications outside of central laboratories. We compare several of these technologies with our own preferred centrifugal flow system, the LabCDTM, with an emphasis on fluid propulsion. LabCDTM has been developed to perform a variety of fluidic processes necessary in diagnostics while dispensing with traditional pumps and valves. The use of the CD-ROM model provides a natural division of the system into an instrument and a disposable component, each with well-defined functions. The CD format also allows for the use of encoded information to integrate process control, data acquisition, and analysis. Finally, the `solid state' nature of the microfluidics and use of standard manufacturing techniques should yield a low- cost platform.

  14. Detection of ESKAPE Bacterial Pathogens at the Point of Care Using Isothermal DNA-Based Assays in a Portable Degas-Actuated Microfluidic Diagnostic Assay Platform

    PubMed Central

    Renner, Lars D.; Zan, Jindong; Hu, Linda I.; Martinez, Manuel; Resto, Pedro J.; Siegel, Adam C.; Torres, Clint; Hall, Sara B.; Slezak, Tom R.

    2016-01-01

    ABSTRACT An estimated 1.5 billion microbial infections occur globally each year and result in ∼4.6 million deaths. A technology gap associated with commercially available diagnostic tests in remote and underdeveloped regions prevents timely pathogen identification for effective antibiotic chemotherapies for infected patients. The result is a trial-and-error approach that is limited in effectiveness, increases risk for patients while contributing to antimicrobial drug resistance, and reduces the lifetime of antibiotics. This paper addresses this important diagnostic technology gap by describing a low-cost, portable, rapid, and easy-to-use microfluidic cartridge-based system for detecting the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) bacterial pathogens that are most commonly associated with antibiotic resistance. The point-of-care molecular diagnostic system consists of a vacuum-degassed microfluidic cartridge preloaded with lyophilized recombinase polymerase amplification (RPA) assays and a small portable battery-powered electronic incubator/reader. The isothermal RPA assays detect the targeted ESKAPE pathogens with high sensitivity (e.g., a limit of detection of ∼10 nucleic acid molecules) that is comparable to that of current PCR-based assays, and they offer advantages in power consumption, engineering, and robustness, which are three critical elements required for the point-of-care setting. IMPORTANCE This paper describes a portable system for rapidly identifying bacteria in resource-limited environments; we highlight the capabilities of the technology by detecting different pathogens within the ESKAPE collection, which cause nosocomial infections. The system is designed around isothermal DNA-based assays housed within an autonomous plastic cartridge that are designed with the end user in mind, who may have limited technological training. Displaying

  15. Screening the Cellular Microenvironment: A Role for Microfluidics

    PubMed Central

    Warrick, Jay W.; Murphy, William L.; Beebe, David J.

    2010-01-01

    The cellular microenvironment is an increasingly discussed topic in cell biology as it has been implicated in the progression of cancer and the maintenance of stem cells. The microenvironment of a cell is an organized combination of extracellular matrix (ECM), cells, and interstitial fluid that influence cellular phenotype through physical, mechanical, and biochemical mechanisms. Screening can be used to map combinations of cells and microenvironments to phenotypic outcomes in a way that can help develop more predictive in vitro models and to better understand phenotypic mechanisms from a systems biology perspective. This paper examines microenvironmental screening in terms of outcomes and benefits, key elements of the screening process, challenges for implementation, and a possible role for microfluidics as the screening platform. To assess microfluidics for use in microenvironmental screening, examples and categories of micro-scale and microfluidic technology are highlighted. Microfluidic technology shows promise for simultaneous control of multiple parameters of the microenvironment and can provide a base for scaling advanced cell-based experiments into automated high-throughput formats. PMID:20190880

  16. Development of online, continuous heavy metals detection and monitoring sensors based on microfluidic plasma reactors

    NASA Astrophysics Data System (ADS)

    Abdul-Majeed, Wameath Sh

    This research is dedicated to develop a fully integrated system for heavy metals determination in water samples based on micro fluidic plasma atomizers. Several configurations of dielectric barrier discharge (DBD) atomizer are designed, fabricated and tested toward this target. Finally, a combination of annular and rectangular DBD atomizers has been utilized to develop a scheme for heavy metals determination. The present thesis has combined both theoretical and experimental investigations to fulfil the requirements. Several mathematical studies are implemented to explore the optimal design parameters for best system performance. On the other hand, expanded experimental explorations are conducted to assess the proposed operational approaches. The experiments were designed according to a central composite rotatable design; hence, an empirical model has been produced for each studied case. Moreover, several statistical approaches are adopted to analyse the system performance and to deduce the optimal operational parameters.. The introduction of the examined analyte to the plasma atomizer has been achieved by applying chemical schemes, where the element in the sample has been derivitized by using different kinds of reducing agents to produce vapour species (e.g. hydrides) for a group of nine elements examined in this research individually and simultaneously. Moreover, other derivatization schemes based on photochemical vapour generation assisted by ultrasound irradiation are also investigated. Generally speaking, the detection limits achieved in this research for the examined set of elements (by applying hydroborate scheme) are found to be acceptable in accordance with the standard limits in drinking water. The results of copper compared with the data from other technologies in the literature, showed a competitive detection limit obtained from applying the developed scheme, with an advantage of conducting simultaneous, fully automated, insitu, online- real time

  17. Portable Analyzer Based on Microfluidics/Nanoengineered Electrochemical Sensors for In-situ Characterization of Mixed Wastes

    SciTech Connect

    Lin, Yuehe; Wang, Joseph

    2004-06-01

    Required characterizations of the DOE's transuranic (TRU) and mixed wastes (MW) before disposing and treatment of the wastes are currently costly and have lengthy turnaround. Research toward developing faster and more sensitive characterization and analysis tools to reduce costs and accelerate throughputs is therefore desirable. This project is aimed at the development of electrochemical sensors, specific to toxic transition metals, uranium, and technetium, that can be integrated into the portable sensor systems. This system development will include fabrication and performance evaluation of electrodes as well as understanding of electrochemically active sites on the electrodes specifically designed for toxic metals, uranium and technetium detection. Subsequently, these advanced measurement units will be incorporated into a microfluidic prototype specifically designed and fabricated for field-deployable characterizations of such species. The electrochemical sensors being invest igated are based on a new class of nanoengineered sorbents, Self-Assembled Monolayer on Mesoporous Supports (SAMMS). SAMMS are highly efficient sorbents due to their interfacial chemistry that can be fine-tuned to selectively sequester a specific target species. Adsorptive stripping voltammetry (AdSV) will be performed on two classes of electrodes: the SAMMS modified carbon paste electrodes, and the SAMMS thin film immobilized on microelectrode arrays. Interfacial chemistry and electrochemistry of metal species on the surfaces of SAMMS-based electrodes will be studied. This fundamental knowledge is required for predicting how the sensors will perform in the real wastes which consist of many interferences/ligands and a spectrum of pH levels. The best electrode for each specific waste constituent will be integrated onto the portable microfluidic platform. Efforts will also be focused on testing the portable microfluidics/electrochemical sensor systems with the selected MW and T RU waste samples

  18. Microfluidic interconnects

    DOEpatents

    Benett, William J.; Krulevitch, Peter A.

    2001-01-01

    A miniature connector for introducing microliter quantities of solutions into microfabricated fluidic devices. The fluidic connector, for example, joins standard high pressure liquid chromatography (HPLC) tubing to 1 mm diameter holes in silicon or glass, enabling ml-sized volumes of sample solutions to be merged with .mu.l-sized devices. The connector has many features, including ease of connect and disconnect; a small footprint which enables numerous connectors to be located in a small area; low dead volume; helium leak-tight; and tubing does not twist during connection. Thus the connector enables easy and effective change of microfluidic devices and introduction of different solutions in the devices.

  19. Capillary-driven microfluidic paper-based analytical devices for lab on a chip screening of explosive residues in soil.

    PubMed

    Ueland, Maiken; Blanes, Lucas; Taudte, Regina V; Stuart, Barbara H; Cole, Nerida; Willis, Peter; Roux, Claude; Doble, Philip

    2016-03-04

    A novel microfluidic paper-based analytical device (μPAD) was designed to filter, extract, and pre-concentrate explosives from soil for direct analysis by a lab on a chip (LOC) device. The explosives were extracted via immersion of wax-printed μPADs directly into methanol soil suspensions for 10min, whereby dissolved explosives travelled upwards into the μPAD circular sampling reservoir. A chad was punched from the sampling reservoir and inserted into a LOC well containing the separation buffer for direct analysis, avoiding any further extraction step. Eight target explosives were separated and identified by fluorescence quenching. The minimum detectable amounts for all eight explosives were between 1.4 and 5.6ng with recoveries ranging from 53-82% from the paper chad, and 12-40% from soil. This method provides a robust and simple extraction method for rapid identification of explosives in complex soil samples.

  20. A High-Voltage Integrated Circuit Engine for a Dielectrophoresis-based Programmable Micro-Fluidic Processor.

    PubMed

    Current, K Wayne; Yuk, Kelvin; McConaghy, Charles; Gascoyne, Peter R C; Schwartz, Jon A; Vykoukal, Jody V; Andrews, Craig

    2005-07-24

    A high-voltage (HV) integrated circuit has been demonstrated to transport droplets on programmable paths across its coated surface. This chip is the engine for a dielectrophoresis (DEP)-based micro-fluidic lab-on-a-chip system. This chip creates DEP forces that move and help inject droplets. Electrode excitation voltage and frequency are variable. With the electrodes driven with a 100V peak-to-peak periodic waveform, the maximum high-voltage electrode waveform frequency is about 200Hz. Data communication rate is variable up to 250kHz. This demonstration chip has a 32×32 array of nominally 100V electrode drivers. It is fabricated in a 130V SOI CMOS fabrication technology, dissipates a maximum of 1.87W, and is about 10.4 mm × 8.2 mm.