Science.gov

Sample records for microfluidic perfusion system

  1. Multiwell cell culture plate format with integrated microfluidic perfusion system

    NASA Astrophysics Data System (ADS)

    Domansky, Karel; Inman, Walker; Serdy, Jim; Griffith, Linda G.

    2006-01-01

    A new cell culture analog has been developed. It is based on the standard multiwell cell culture plate format but it provides perfused three-dimensional cell culture capability. The new capability is achieved by integrating microfluidic valves and pumps into the plate. The system provides a means to conduct high throughput assays for target validation and predictive toxicology in the drug discovery and development process. It can be also used for evaluation of long-term exposure to drugs or environmental agents or as a model to study viral hepatitis, cancer metastasis, and other diseases and pathological conditions.

  2. 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.

  3. Prevention of air bubble formation in a microfluidic perfusion cell culture system using a microscale bubble trap.

    PubMed

    Sung, Jong Hwan; Shuler, Michael L

    2009-08-01

    Formation of air bubbles is a serious obstacle to a successful operation of a long-term microfluidic systems using cell culture. We developed a microscale bubble trap that can be integrated with a microfluidic device to prevent air bubbles from entering the device. It consists of two PDMS (polydimethyldisiloxane) layers, a top layer providing barriers for blocking bubbles and a bottom layer providing alternative fluidic paths. Rather than relying solely on the buoyancy of air bubbles, bubbles are physically trapped and prevented from entering a microfluidic device. Two different modes of a bubble trap were fabricated, an independent module that is connected to the main microfluidic system by tubes, and a bubble trap integrated with a main system. The bubble trap was tested for the efficiency of bubble capture, and for potential effects a bubble trap may have on fluid flow pattern. The bubble trap was able to efficiently trap air bubbles of up to 10 mul volume, and the presence of captured air bubbles did not cause alterations in the flow pattern. The performance of the bubble trap in a long-term cell culture with medium recirculation was examined by culturing a hepatoma cell line in a microfluidic cell culture device. This bubble trap can be useful for enhancing the consistency of microfluidic perfusion cell culture operation.

  4. A 3D microfluidic perfusion system made from glass for multiparametric analysis of stimulus-secretioncoupling in pancreatic islets.

    PubMed

    Schulze, Torben; Mattern, Kai; Früh, Eike; Hecht, Lars; Rustenbeck, Ingo; Dietzel, Andreas

    2017-09-01

    Microfluidic perfusion systems (MPS) are well suited to perform multiparametric measurements with small amounts of tissue to function as an Organ on Chip device (OOC). Such microphysiolgical characterization is particularly valuable in research on the stimulus-secretion-coupling of pancreatic islets. Pancreatic islets are fully functional competent mini-organs, which serve as fuel sensors and transduce metabolic activity into rates of hormone secretion. To enable the simultaneous measurement of fluorescence and oxygen consumption we designed a microfluidic perfusion system from borosilicate glass by 3D femtosecond laser ablation. Retention of islets was accomplished by a plain well design. The characteristics of flow and shear force in the microchannels and wells were simulated and compared with the measured exchange of the perfusion media. Distribution of latex beads, MIN6 cell pseudo islets and isolated mouse islets in the MPS was characterized in dependence of flow rate and well depth. Overall, the observations suggested that a sufficient retention of the islets at low shear stress, together with sufficient exchange of test medium, was achieved at a well depth of 300 μm and perfusion rates between 40 and 240 μl/min. This enabled multiparametric measurement of oxygen consumption, NAD(P)H autofluorescence, cytosolic Ca(2+) concentration, and insulin secretion by isolated mouse islets. After appropriate correction for different lag times, kinetics of these processes could be compared. Such measurements permit a more precise insight into metabolic changes underlying the regulation of insulin secretion. Thus, rapid prototyping using laser ablation enables flexible adaption of borosilicate MPS designs to different demands of biomedical research.

  5. Sequential assembly of 3D perfusable microfluidic hydrogels.

    PubMed

    He, Jiankang; Zhu, Lin; Liu, Yaxiong; Li, Dichen; Jin, Zhongmin

    2014-11-01

    Bottom-up tissue engineering provides a promising way to recreate complex structural organizations of native organs in artificial constructs by assembling functional repeating modules. However, it is challenging for current bottom-up strategies to simultaneously produce a controllable and immediately perfusable microfluidic network in modularly assembled 3D constructs. Here we presented a bottom-up strategy to produce perfusable microchannels in 3D hydrogels by sequentially assembling microfluidic modules. The effects of agarose-collagen composition on microchannel replication and 3D assembly of hydrogel modules were investigated. The unique property of predefined microchannels in transporting fluids within 3D assemblies was evaluated. Endothelial cells were incorporated into the microfluidic network of 3D hydrogels for dynamic culture in a house-made bioreactor system. The results indicated that the sequential assembly method could produce interconnected 3D predefined microfluidic networks in optimized agarose-collagen hydrogels, which were fully perfusable and successfully functioned as fluid pathways to facilitate the spreading of endothelial cells. We envision that the presented method could be potentially used to engineer 3D vascularized parenchymal constructs by encapsulating primary cells in bulk hydrogels and incorporating endothelial cells in predefined microchannels.

  6. A practical guide to microfluidic perfusion culture of adherent mammalian cells.

    PubMed

    Kim, Lily; Toh, Yi-Chin; Voldman, Joel; Yu, Hanry

    2007-06-01

    Culturing cells at microscales allows control over microenvironmental cues, such as cell-cell and cell-matrix interactions; the potential to scale experiments; the use of small culture volumes; and the ability to integrate with microsystem technologies for on-chip experimentation. Microfluidic perfusion culture in particular allows controlled delivery and removal of soluble biochemical molecules in the extracellular microenvironment, and controlled application of mechanical forces exerted via fluid flow. There are many challenges to designing and operating a robust microfluidic perfusion culture system for routine culture of adherent mammalian cells. The current literature on microfluidic perfusion culture treats microfluidic design, device fabrication, cell culture, and micro-assays independently. Here we systematically present and discuss important design considerations in the context of the entire microfluidic perfusion culture system. These design considerations include the choice of materials, culture configurations, microfluidic network fabrication and micro-assays. We also present technical issues such as sterilization; seeding cells in both 2D and 3D configurations; and operating the system under optimized mass transport and shear stress conditions, free of air-bubbles. The integrative and systematic treatment of the microfluidic system design and fabrication, cell culture, and micro-assays provides novices with an effective starting point to build and operate a robust microfludic perfusion culture system for various applications.

  7. Pressure-driven microfluidic perfusion culture device for integrated dose-response assays.

    PubMed

    Hattori, Koji; Sugiura, Shinji; Kanamori, Toshiyuki

    2013-12-01

    Cell-based assays are widely used in the various stages of drug discovery. Advances in microfluidic systems over the past two decades have enabled them to become a powerful tool for cell-based assays to achieve both reliability and high throughput. The interface between the micro-world and macro-world is important in industrial assay processes. Therefore, microfluidic cell-based assays using pressure-driven liquid handling are an ideal platform for integrated assays. The aim of this article is to review recent advancements in microfluidic cell-based assays focusing on a pressure-driven perfusion culture device. Here, we review the development of microfluidic cell-based assay devices and discuss the techniques involved in designing a microfluidic network, device fabrication, liquid and cell manipulation, and detection schemes for pressure-driven perfusion culture devices. Finally, we describe recent progress in semiautomatic and reliable pressure-driven microfluidic cell-based assays.

  8. A pump-free membrane-controlled perfusion microfluidic platform

    PubMed Central

    Goral, Vasiliy N.; Tran, Elizabeth; Yuen, Po Ki

    2015-01-01

    In this article, we present a microfluidic platform for passive fluid pumping for pump-free perfusion cell culture, cell-based assay, and chemical applications. By adapting the passive membrane-controlled pumping principle from the previously developed perfusion microplate, which utilizes a combination of hydrostatic pressure generated by different liquid levels in the wells and fluid wicking through narrow strips of a porous membrane connecting the wells to generate fluid flow, a series of pump-free membrane-controlled perfusion microfluidic devices was developed and their use for pump-free perfusion cell culture and cell-based assays was demonstrated. Each pump-free membrane-controlled perfusion microfluidic device comprises at least three basic components: an open well for generating fluid flow, a micron-sized deep chamber/channel for cell culture or for fluid connection, and a wettable porous membrane for controlling the fluid flow. Each component is fluidically connected either by the porous membrane or by the micron-sized deep chamber/channel. By adapting and incorporating the passive membrane-controlled pumping principle into microfluidic devices, all the benefits of microfluidic technologies, such as small sample volumes, fast and efficient fluid exchanges, and fluid properties at the micro-scale, can be fully taken advantage of with this pump-free membrane-controlled perfusion microfluidic platform. PMID:26392835

  9. A perfusion-capable microfluidic bioreactor for assessing microbial heterologous protein production

    PubMed Central

    Mozdzierz, Nicholas J.; Love, Kerry R.; Lee, Kevin S.; Lee, Harry L. T.; Shah, Kartik A.; Ram, Rajeev J.

    2015-01-01

    We present an integrated microfluidic bioreactor for fully continuous perfusion cultivation of suspended microbial cell cultures. This system allowed continuous and stable heterologous protein expression by sustaining the cultivation of Pichia pastoris over 11 days. This technical capability also allowed testing the impact of perfusion conditions on protein expression. This advance should enable small-scale models for process optimization in continuous biomanufacturing. PMID:26055071

  10. Microfluidic perfusion for regulating diffusible signaling in stem cells.

    PubMed

    Blagovic, Katarina; Kim, Lily Y; Voldman, Joel

    2011-01-01

    \\paracrine processes previously hidden in conventional culture systems, our results establish microfluidic perfusion as a technique to study and manipulate diffusible signaling in cell systems.

  11. Microfluidic perfusion culture of human induced pluripotent stem cells under fully defined culture conditions.

    PubMed

    Yoshimitsu, Ryosuke; Hattori, Koji; Sugiura, Shinji; Kondo, Yuki; Yamada, Rotaro; Tachikawa, Saoko; Satoh, Taku; Kurisaki, Akira; Ohnuma, Kiyoshi; Asashima, Makoto; Kanamori, Toshiyuki

    2014-05-01

    Human induced pluripotent stem cells (hiPSCs) are a promising cell source for drug screening. For this application, self-renewal or differentiation of the cells is required, and undefined factors in the culture conditions are not desirable. Microfluidic perfusion culture allows the production of small volume cultures with precisely controlled microenvironments, and is applicable to high-throughput cellular environment screening. Here, we developed a microfluidic perfusion culture system for hiPSCs that uses a microchamber array chip under defined extracellular matrix (ECM) and culture medium conditions. By screening various ECMs we determined that fibronectin and laminin are appropriate for microfluidic devices made out of the most popular material, polydimethylsiloxane (PDMS). We found that the growth rate of hiPSCs under pressure-driven perfusion culture conditions was higher than under static culture conditions in the microchamber array. We applied our new system to self-renewal and differentiation cultures of hiPSCs, and immunocytochemical analysis showed that the state of the hiPSCs was successfully controlled. The effects of three antitumor drugs on hiPSCs were comparable between microchamber array and 96-well plates. We believe that our system will be a platform technology for future large-scale screening of fully defined conditions for differentiation cultures on integrated microfluidic devices. © 2013 Wiley Periodicals, Inc.

  12. A 3D printed microfluidic perfusion device for multicellular spheroid cultures.

    PubMed

    Ong, Louis Jun Ye; Islam, Anik Badhan; DasGupta, Ramanuj; Iyer, Narayanan Gopalakkrishna; Leo, Hwa Liang; Toh, Yi-Chin

    2017-09-11

    The advent of 3D printing technologies promises to make microfluidic organ-on-chip technologies more accessible for the biological research community. To date, hydrogel-encapsulated cells have been successfully incorporated into 3D printed microfluidic devices. However, there is currently no 3D printed microfluidic device that can support multicellular spheroid culture, which facilitates extensive cell-cell contacts important for recapitulating many multicellular functional biological structures. Here, we report a first instance of fabricating a 3D printed microfluidic cell culture device capable of directly immobilizing and maintaining the viability and functionality of 3D multicellular spheroids. We evaluated the feasibility of two common 3D printing technologies i.e. stereolithography (SLA) and PolyJet printing, and found that SLA could prototype a device comprising of cell immobilizing micro-structures that were housed within a microfluidic network with higher fidelity. We have also implemented a pump-free perfusion system, relying on gravity-driven flow to perform medium perfusion in order to reduce the complexity and footprint of the device setup, thereby improving its adaptability into a standard biological laboratory. Finally, we demonstrated the biological performance of the 3D printed device by performing pump-free perfusion cultures of patient-derived parental and metastatic oral squamous cell carcinoma tumor and liver cell (HepG2) spheroids with good cell viability and functionality. This paper presents a proof-of-concept in simplifying and integrating the prototyping and operation of a microfluidic spheroid culture device, which will facilitate its applications in various drug efficacy, metabolism and toxicity studies.

  13. A microfluidically perfused three dimensional human liver model.

    PubMed

    Rennert, Knut; Steinborn, Sandra; Gröger, Marko; Ungerböck, Birgit; Jank, Anne-Marie; Ehgartner, Josef; Nietzsche, Sandor; Dinger, Julia; Kiehntopf, Michael; Funke, Harald; Peters, Frank T; Lupp, Amelie; Gärtner, Claudia; Mayr, Torsten; Bauer, Michael; Huber, Otmar; Mosig, Alexander S

    2015-12-01

    Within the liver, non-parenchymal cells (NPCs) are critically involved in the regulation of hepatocyte polarization and maintenance of metabolic function. We here report the establishment of a liver organoid that integrates NPCs in a vascular layer composed of endothelial cells and tissue macrophages and a hepatic layer comprising stellate cells co-cultured with hepatocytes. The three-dimensional liver organoid is embedded in a microfluidically perfused biochip that enables sufficient nutrition supply and resembles morphological aspects of the human liver sinusoid. It utilizes a suspended membrane as a cell substrate mimicking the space of Disse. Luminescence-based sensor spots were integrated into the chip to allow online measurement of cellular oxygen consumption. Application of microfluidic flow induces defined expression of ZO-1, transferrin, ASGPR-1 along with an increased expression of MRP-2 transporter protein within the liver organoids. Moreover, perfusion was accompanied by an increased hepatobiliary secretion of 5(6)-carboxy-2',7'-dichlorofluorescein and an enhanced formation of hepatocyte microvilli. From this we conclude that the perfused liver organoid shares relevant morphological and functional characteristics with the human liver and represents a new in vitro research tool to study human hepatocellular physiology at the cellular level under conditions close to the physiological situation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Microfluidic Perfusion for Regulating Diffusible Signaling in Stem Cells

    PubMed Central

    Blagovic, Katarina; Kim, Lily Y.; Voldman, Joel

    2011-01-01

    -independent pathways. Overall, by uncovering autocrine\\paracrine processes previously hidden in conventional culture systems, our results establish microfluidic perfusion as a technique to study and manipulate diffusible signaling in cell systems. PMID:21829665

  15. Continuous perfusion microfluidic cell culture array for high-throughput cell-based assays.

    PubMed

    Hung, Paul J; Lee, Philip J; Sabounchi, Poorya; Lin, Robert; Lee, Luke P

    2005-01-05

    We present for the first time a microfluidic cell culture array for long-term cellular monitoring. The 10 x 10 array could potentially assay 100 different cell-based experiments in parallel. The device was designed to integrate the processes used in typical cell culture experiments on a single self-contained microfluidic system. Major functions include repeated cell growth/passage cycles, reagent introduction, and real-time optical analysis. The single unit of the array consists of a circular microfluidic chamber, multiple narrow perfusion channels surrounding the main chamber, and four ports for fluidic access. Human carcinoma (HeLa) cells were cultured inside the device with continuous perfusion of medium at 37 degrees C. The observed doubling time was 1.4 +/- 0.1 days with a peak cell density of approximately 2.5*10(5) cells/cm(2). Cell assay was demonstrated by monitoring the fluorescence localization of calcein AM from 1 min to 10 days after reagent introduction. Confluent cell cultures were passaged within the microfluidic chambers using trypsin and successfully regrown, suggesting a stable culture environment suitable for continuous operation. The cell culture array could offer a platform for a wide range of assays with applications in drug screening, bioinformatics, and quantitative cell biology. (c) 2004 Wiley Periodicals, Inc.

  16. Experimental Microfluidic System

    NASA Technical Reports Server (NTRS)

    Culbertson, Christopher; Gonda, Steve; Ramsey, John Michael

    2005-01-01

    The ultimate goal of this project is to integrate microfluidic devices with NASA's space bioreactor systems. In such a system, the microfluidic device would provide realtime feedback control of the bioreactor by monitoring pH, glucose, and lactate levels in the cell media; and would provide an analytical capability to the bioreactor in exterrestrial environments for monitoring bioengineered cell products and health changes in cells due to environmental stressors. Such integrated systems could be used as biosentinels both in space and on planet surfaces. The objective is to demonstrate the ability of microfabricated devices to repeatedly and reproducibly perform bead cytometry experiments in micro, lunar, martian, and hypergravity (1.8g).

  17. Multiphysics simulation of a microfluidic perfusion chamber for brain slice physiology.

    PubMed

    Caicedo, Hector H; Hernandez, Maximiliano; Fall, Christopher P; Eddington, David T

    2010-10-01

    Understanding and optimizing fluid flows through in vitro microfluidic perfusion systems is essential in mimicking in vivo conditions for biological research. In a previous study a microfluidic brain slice device (microBSD) was developed for microscale electrophysiology investigations. The device consisted of a standard perfusion chamber bonded to a polydimethylsiloxane (PDMS) microchannel substrate. Our objective in this study is to characterize the flows through the microBSD by using multiphysics simulations of injections into a pourous matrix to identify optimal spacing of ports. Three-dimensional computational fluid dynamic (CFD) simulations are performed with CFD-ACE + software to model, simulate, and assess the transport of soluble factors through the perfusion bath, the microchannels, and a material that mimics the porosity, permeability and tortuosity of brain tissue. Additionally, experimental soluble factor transport through a brain slice is predicted by and compared to simulated fluid flow in a volume that represents a porous matrix material. The computational results are validated with fluorescent dye experiments.

  18. The application of an optically switched dielectrophoretic (ODEP) force for the manipulation and assembly of cell-encapsulating alginate microbeads in a microfluidic perfusion cell culture system for bottom-up tissue engineering.

    PubMed

    Lin, Yen-Heng; Yang, Ya-Wen; Chen, Yi-Dao; Wang, Shih-Siou; Chang, Yu-Han; Wu, Min-Hsien

    2012-03-21

    This study reports the utilisation of an optically switched dielectrophoretic (ODEP) force for the manipulation and assembly of cell-encapsulating alginate microbeads in a microfluidic perfusion cell culture system for bottom-up tissue engineering. One of the key features of this system is the ODEP force-based mechanism, which allows a commercial projector to be coupled with a computer to manipulate and assemble cell-encapsulating microbeads in an efficient, manageable, and user-friendly manner. Another distinctive feature is the design of the microfluidic cell culture chip, which allows the patterned cell-encapsulating microbeads to be cultivated on site under culture medium perfusion conditions. For demonstrating its application in bottom-up cartilage tissue engineering, chondrocyte-encapsulating alginate microbeads varying in encapsulated cell densities were generated. The manipulation forces associated with operating the alginate microbeads were experimentally evaluated. The results revealed that the measured manipulation forces increased with increases in both the applied electric voltage and the number of cells in the alginate microbeads. Nevertheless, the observed manipulation force was found to be independent of the size of the cell-free alginate microbeads. It can be speculated that the friction force may influence the estimation of the ODEP force within the experimental conditions investigated. In this study, chondrocyte-encapsulating alginate microbeads with three different cell densities were manipulated and assembled in the proposed microfluidic system to form a compact sheet-like cell culture construct that imitates the cell distribution in the cross-section of native articular cartilage. Moreover, the demonstration case also showed that the cell viability of the cultured cells in the microfluidic system remained as high as 96 ± 2%. In this study, four sheet-like cell culture constructs were stacked to create a larger assembled cell culture construct

  19. Detachably assembled microfluidic device for perfusion culture and post-culture analysis of a spheroid array.

    PubMed

    Sakai, Yusuke; Hattori, Koji; Yanagawa, Fumiki; Sugiura, Shinji; Kanamori, Toshiyuki; Nakazawa, Kohji

    2014-07-01

    Microfluidic devices permit perfusion culture of three-dimensional (3D) tissue, mimicking the flow of blood in vascularized 3D tissue in our body. Here, we report a microfluidic device composed of a two-part microfluidic chamber chip and multi-microwell array chip able to be disassembled at the culture endpoint. Within the microfluidic chamber, an array of 3D tissue aggregates (spheroids) can be formed and cultured under perfusion. Subsequently, detailed post-culture analysis of the spheroids collected from the disassembled device can be performed. This device facilitates uniform spheroid formation, growth analysis in a high-throughput format, controlled proliferation via perfusion flow rate, and post-culture analysis of spheroids. We used the device to culture spheroids of human hepatocellular carcinoma (HepG2) cells under two controlled perfusion flow rates. HepG2 spheroids exhibited greater cell growth at higher perfusion flow rates than at lower perfusion flow rates, and exhibited different metabolic activity and mRNA and protein expression under the different flow rate conditions. These results show the potential of perfusion culture to precisely control the culture environment in microfluidic devices. The construction of spheroid array chambers allows multiple culture conditions to be tested simultaneously, with potential applications in toxicity and drug screening. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Integrated microfluidic systems.

    PubMed

    Kaneda, Shohei; Fujii, Teruo

    2010-01-01

    Using unique physical phenomena at the microscale, such as laminar flow, mixing by diffusion, relative increase of the efficiency of heat exchange, surface tension and friction due to the increase of surface-to-volume ratio by downscaling, research in the field of microfluidic devices, aims at miniaturization of (bio)chemical apparatus for high-throughput analyses. Microchannel networks as core components of microfluidic devices are fabricated on various materials, such as silicon, glass, polymers, metals, etc., using microfabrication techniques adopted from the semiconductor industry and microelectromechanical systems (MEMS) technology, enabling integration of the components capable of performing various operations in microchannel networks. This chapter describes examples of diverse integrated microfluidic devices that incorporate functional components such as heaters for reaction temperature control, micropumps for liquid transportation, air vent structures for pneumatic manipulation of small volume droplets, optical fibers with aspherical lens structures for fluorescence detection, and electrochemical sensors for monitoring of glucose consumption during cell culture. The focus of this review is these integrated components and systems that realize useful functionalities for biochemical analyses.

  1. Integrated Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Kaneda, Shohei; Fujii, Teruo

    Using unique physical phenomena at the microscale, such as laminar flow, mixing by diffusion, relative increase of the efficiency of heat exchange, surface tension and friction due to the increase of surface-to-volume ratio by downscaling, research in the field of microfluidic devices, aims at miniaturization of (bio)chemical apparatus for high-throughput analyses. Microchannel networks as core components of microfluidic devices are fabricated on various materials, such as silicon, glass, polymers, metals, etc., using microfabrication techniques adopted from the semiconductor industry and microelectromechanical systems (MEMS) technology, enabling integration of the components capable of performing various operations in microchannel networks. This chapter describes examples of diverse integrated microfluidic devices that incorporate functional components such as heaters for reaction temperature control, micropumps for liquid transportation, air vent structures for pneumatic manipulation of small volume droplets, optical fibers with aspherical lens structures for fluorescence detection, and electrochemical sensors for monitoring of glucose consumption during cell culture. The focus of this review is these integrated components and systems that realize useful functionalities for biochemical analyses.

  2. 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.

  3. Brain slice stimulation using a microfluidic network and standard perfusion chamber.

    PubMed

    Shaikh Mohammed, Javeed; Caicedo, Hugo; Fall, Christopher P; Eddington, David T

    2007-01-01

    We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The two-level microfluidic device is fabricated using a two-step standard negative resist lithography process. The first level contains microchannels with inlet and outlet ports at each end. The second level contains microscale circular holes located midway of the channel length and centered along with channel width. Passive pumping method is used to pump fluids from the inlet port to the outlet port. The microfluidic device is integrated with off-the-shelf perfusion chambers and allows seamless integration with the electrophysiology setup. The fluids introduced at the inlet ports flow through the microchannels towards the outlet ports and also escape through the circular openings located on top of the microchannels into the bath of the perfusion. Thus the bottom surface of the brain slice placed in the perfusion chamber bath and above the microfluidic device can be exposed with different neurotransmitters. The microscale thickness of the microfluidic device and the transparent nature of the materials [glass coverslip and PDMS (polydimethylsiloxane)] used to make the microfluidic device allow microscopy of the brain slice. The microfluidic device allows modulation (both spatial and temporal) of the chemical stimuli introduced to the brain slice microenvironments.

  4. An easy to assemble microfluidic perfusion device with a magnetic clamp

    PubMed Central

    Tkachenko, Eugene; Gutierrez, Edgar; Ginsberg, Mark H.; Groisman, Alex

    2009-01-01

    We have built and characterized a magnetic clamp for reversible sealing of PDMS microfluidic chips against cover glasses with cell cultures and a microfluidic chip for experiments on shear stress response of endothelial cells. The magnetic clamp exerts a reproducible uniform pressure on the microfluidic chip, achieving fast and reliable sealing for liquid pressures up to 40 kPa inside the chip with <10% deformations of microchannels and minimal variations of the substrate shear stress in perfusion flow. The microfluidic chip has 8 test regions with the substrate shear stress varying by a factor of 2 between each region, thus covering a 128-fold range from low venous to arterial. The perfusion is driven by differential pressure, which makes it possible to create pulsatile flows mimicking pulsing in the vasculature. The setup is tested by 15 – 40 hours perfusions over endothelial monolayers with shear stress in the range of 0.07 - 9 dyn/cm2. Excellent cell viability at all shear stresses and alignment of cells along the flow at high shear stresses are repeatedly observed. A scratch wound healing assay under a shear flow is demonstrated and cell migration velocities are measured. Transfection of cells with a fluorescent protein is performed, and migrating fluorescent cells are imaged at a high resolution under shear flow in real time. The magnetic clamp can be closed with minimal mechanical perturbation to cells on the substrate and used with a variety of microfluidic chips for experiments with adherent and non-adherent cells. PMID:19350090

  5. Optimal Homogenization of Perfusion Flows in Microfluidic Bio-Reactors: A Numerical Study

    PubMed Central

    Okkels, Fridolin; Dufva, Martin; Bruus, Henrik

    2011-01-01

    In recent years, the interest in small-scale bio-reactors has increased dramatically. To ensure homogeneous conditions within the complete area of perfused microfluidic bio-reactors, we develop a general design of a continually feed bio-reactor with uniform perfusion flow. This is achieved by introducing a specific type of perfusion inlet to the reaction area. The geometry of these inlets are found using the methods of topology optimization and shape optimization. The results are compared with two different analytic models, from which a general parametric description of the design is obtained and tested numerically. Such a parametric description will generally be beneficial for the design of a broad range of microfluidic bioreactors used for, e.g., cell culturing and analysis and in feeding bio-arrays. PMID:21298040

  6. Optimal homogenization of perfusion flows in microfluidic bio-reactors: a numerical study.

    PubMed

    Okkels, Fridolin; Dufva, Martin; Bruus, Henrik

    2011-01-27

    In recent years, the interest in small-scale bio-reactors has increased dramatically. To ensure homogeneous conditions within the complete area of perfused microfluidic bio-reactors, we develop a general design of a continually feed bio-reactor with uniform perfusion flow. This is achieved by introducing a specific type of perfusion inlet to the reaction area. The geometry of these inlets are found using the methods of topology optimization and shape optimization. The results are compared with two different analytic models, from which a general parametric description of the design is obtained and tested numerically. Such a parametric description will generally be beneficial for the design of a broad range of microfluidic bioreactors used for, e.g., cell culturing and analysis and in feeding bio-arrays.

  7. 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.

  8. Mixing in Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Beskok, A.

    Flow and species transport in micro-scales experience laminar, even Stokes flow conditions. In absence of turbulence, species mixing becomes diffusion dominated, and requires very long mixing length scales (l m ). This creates significant challenges in the design of Lab-on-a-chip (LOC) devices, where mixing of macromolecules and biological species with very low mass diffusivities are often desired. The objectives of this chapter are to introduce concepts relevant to mixing enhancement in microfluidic systems, and guide readers in the design of new mixers via numerical simulations. A distinguishing feature is the identification of flow kinematics that enhance mixing, followed with systematic characterization of mixing as a function of the Schmidt number at fixed kinematic conditions. In this chapter, we briefly review the routes to achieve chaotic advection in Stokes flow, and then illustrate the characteri-zation of a continuous flow chaotic stirrer via appropriate numerical tools, including the Poincaré section, finite time Lyapunov exponent, and mixing index.

  9. Blood Perfusion in Microfluidic Models of Pulmonary Capillary Networks: Role of Geometry and Hematocrit

    NASA Astrophysics Data System (ADS)

    Stauber, Hagit; Waisman, Dan; Sznitman, Josue; Technion-IIT Team; Department of Neonatology Carmel Medical Center; Faculty of Medicine-Technion IIT Collaboration

    2015-11-01

    Microfluidic platforms are increasingly used to study blood microflows at true physiological scale due to their ability to overcome manufacturing obstacle of complex anatomical morphologies, such as the organ-specific architectures of the microcirculation. In the present work, we utilize microfluidic platforms to devise in vitro models of the underlying pulmonary capillary networks (PCN), where capillary lengths and diameters are similar to the size of RBCs (~ 5-10 μm). To better understand flow characteristics and dispersion of red blood cells (RBCs) in PCNs, we have designed microfluidic models of alveolar capillary beds inspired by the seminal ``sheet flow'' model of Fung and Sobin (1969). Our microfluidic PCNs feature confined arrays of staggered pillars with diameters of ~ 5,7 and 10 μm, mimicking the dense structure of pulmonary capillary meshes. The devices are perfused with suspensions of RBCs at varying hematocrit levels under different flow rates. Whole-field velocity patterns using micro-PIV and single-cell tracking using PTV are obtained with fluorescently-labelled RBCs and discussed. Our experiments deliver a real-scale quantitative description of RBC perfusion characteristics across the pulmonary capillary microcirculation.

  10. Microfluidic system for in-vitro hypoxia assays

    NASA Astrophysics Data System (ADS)

    Busek, M.; Grünzner, S.; Steege, T.; Steinfelder, C.; Schmieder, F.; Klotzbach, U.; Sonntag, F.

    2017-02-01

    Hereby presented is a microfluidic system, including a micro pump, an oxygenator and a cell culture chamber for perfusion controlled hypoxia assays. It consists of laser-structured polycarbonate (PC) foils and an elastomeric membrane which were joined together using thermal diffusion bonding. The elastomer forms an oxygenator element. The microfluidic system is characterized using non-invasive flow measurement based on micro-Particle-ImageVelocimetry (μPIV) and optical oxygen measurement utilizing the oxygen dependent fluorescence decay. Based on those experimental results and mathematical considerations, the oxygenator and mass transport phenomena within the microfluidic system can be described. This oxygen sensor, the micro pump, a controlling device and the gas mixture at the oxygenator forms a regulatory circuit to adjust the oxygen content in the cell culture chamber and helps to produce well-defined hypoxic conditions for the cells.

  11. A microfluidic perfusion platform for cultivation and screening study of motile microalgal cells

    PubMed Central

    Eu, Young-Jae; Park, Hye-Sun; Kim, Dong-Pyo; Wook Hong, Jong

    2014-01-01

    Systematic screening of algal cells is getting huge interest due to their capability of producing lipid-based biodiesel. Here, we introduce a new microfluidic platform composed of an array of perfusion chambers designed for long-term cultivation and preliminary screening of motile microalgal cells through loading and releasing of cells to and from the chambers. The chemical environment in each perfusion chamber was independently controlled for 5 days. The effect of nitrogen-depletion on the lipid production, phototaxis behavior in the absence of Ca2+, and cytotoxic effect of herbicide on microalgal cells was successfully monitored and compared with simultaneous control experiments on the platform. The present methodology could be extended to effective screening of algal cells and various cell lines for the production of biodiesel and other useful chemicals. PMID:24803962

  12. Ice matrix in reconfigurable microfluidic systems

    NASA Astrophysics Data System (ADS)

    Bossi, A. M.; Vareijka, M.; Piletska, E. V.; Turner, A. P. F.; Meglinski, I.; Piletsky, S. A.

    2013-07-01

    Microfluidic devices find many applications in biotechnologies. Here, we introduce a flexible and biocompatible microfluidic ice-based platform with tunable parameters and configuration of microfluidic patterns that can be changed multiple times during experiments. Freezing and melting of cavities, channels and complex relief structures created and maintained in the bulk of ice by continuous scanning of an infrared laser beam are used as a valve action in microfluidic systems. We demonstrate that pre-concentration of samples and transport of ions and dyes through the open channels created can be achieved in ice microfluidic patterns by IR laser-assisted zone melting. The proposed approach can be useful for performing separation and sensing processes in flexible reconfigurable microfluidic devices.

  13. Microfluidic Systems for Biosensing

    PubMed Central

    Liu, Kuo-Kang; Wu, Ren-Guei; Chuang, Yun-Ju; Khoo, Hwa Seng; Huang, Shih-Hao; Tseng, Fan-Gang

    2010-01-01

    In the past two decades, Micro Fluidic Systems (MFS) have emerged as a powerful tool for biosensing, particularly in enriching and purifying molecules and cells in biological samples. Compared with conventional sensing techniques, distinctive advantages of using MFS for biomedicine include ultra-high sensitivity, higher throughput, in-situ monitoring and lower cost. This review aims to summarize the recent advancements in two major types of micro fluidic systems, continuous and discrete MFS, as well as their biomedical applications. The state-of-the-art of active and passive mechanisms of fluid manipulation for mixing, separation, purification and concentration will also be elaborated. Future trends of using MFS in detection at molecular or cellular level, especially in stem cell therapy, tissue engineering and regenerative medicine, are also prospected. PMID:22163570

  14. Electrokinetic Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Santiago, Juan

    2005-03-01

    Microfabrication technology has enabled the application of electrokinetics as a method of performing chemical analyses and achieving liquid pumping in electronically-controlled microchip systems with no moving parts. Electrokinetics involves the interaction of solid surfaces, ionic solutions, and electric fields. Electric fields can be used to generate bulk fluid motion (electroosmosis) and to separate charged species (electrophoresis). Microfabrication technology has enabled the application of electrokinetics as a method of performing chemical analyses and achieving liquid pumping in electronically-controlled microsystems with no moving parts. This seminar reviews progress at Stanford including methods for sample stacking in capillary electrophoresis assays and fundamental studies of electrokinetic flow instabilities. Field amplified sample stacking (FASS) leverages conductivity gradients as a robust method of increasing sample concentration prior to electrophoretic separation. A major challenge to achieving robust, high-efficiency FASS is the role of electrokinetic instabilities (EKI) generated by a coupling of electric fields and ionic conductivity gradients. This coupling results in electric body forces in the bulk liquid that can generate instabilities. Suppression and/or control of electrokinetic flow instabilities is critical as they dramatically increase dispersion rates and thereby limit stacking efficiency. We have identified the key physical mechanisms in EKI; developed generalized models for electrokinetic systems; and validated the models with experiments. We have applied this understanding to the development of chip systems that achieve signal increases of more than 20,000 fold using FASS. This stacking ratio is over 200 times larger than previous on-chip FASS devices.

  15. Modular microfluidic system for biological sample preparation

    DOEpatents

    Rose, Klint A.; Mariella, Jr., Raymond P.; Bailey, Christopher G.; Ness, Kevin Dean

    2015-09-29

    A reconfigurable modular microfluidic system for preparation of a biological sample including a series of reconfigurable modules for automated sample preparation adapted to selectively include a) a microfluidic acoustic focusing filter module, b) a dielectrophoresis bacteria filter module, c) a dielectrophoresis virus filter module, d) an isotachophoresis nucleic acid filter module, e) a lyses module, and f) an isotachophoresis-based nucleic acid filter.

  16. Microfluidic microarray systems and methods thereof

    DOEpatents

    West, Jay A. A. [Castro Valley, CA; Hukari, Kyle W [San Ramon, CA; Hux, Gary A [Tracy, CA

    2009-04-28

    Disclosed are systems that include a manifold in fluid communication with a microfluidic chip having a microarray, an illuminator, and a detector in optical communication with the microarray. Methods for using these systems for biological detection are also disclosed.

  17. Long term perfusion system supporting adipogenesis

    PubMed Central

    Abbott, Rosalyn D.; Raja, Waseem K.; Wang, Rebecca Y.; Stinson, Jordan A.; Glettig, Dean L.; Burke, Kelly A.; Kaplan, David L.

    2015-01-01

    Adipose tissue engineered models are needed to enhance our understanding of disease mechanisms and for soft tissue regenerative strategies. Perfusion systems generate more physiologically relevant and sustainable adipose tissue models, however adipocytes have unique properties that make culturing them in a perfusion environment challenging. In this paper we describe the methods involved in the development of two perfusion culture systems (2D and 3D) to test their applicability for long term in vitro adipogenic cultures. It was hypothesized that a silk protein biomaterial scaffold would provide a 3D framework, in combination with perfusion flow, to generate a more physiologically relevant sustainable adipose tissue engineered model than 2D cell culture. Consistent with other studies evaluating 2D and 3D culture systems for adipogenesis we found that both systems successfully model adipogensis, however 3D culture systems were more robust, providing the mechanical structure required to contain the large, fragile adipocytes that were lost in 2D perfused culture systems. 3D perfusion also stimulated greater lipogenesis and lipolysis and resulted in decreased secretion of LDH compared to 2D perfusion. Regardless of culture configuration (2D or 3D) greater glycerol was secreted with the increased nutritional supply provided by perfusion of fresh media. These results are promising for adipose tissue engineering applications including long term cultures for studying disease mechanisms and regenerative approaches, where both acute (days to weeks) and chronic (weeks to months) cultivation are critical for useful insight. PMID:25843606

  18. Endothelial Cell Culture Under Perfusion On A Polyester-Toner Microfluidic Device.

    PubMed

    Urbaczek, Ana Carolina; Leão, Paulo Augusto Gomes Carneiro; Souza, Fayene Zeferino Ribeiro de; Afonso, Ana; Vieira Alberice, Juliana; Cappelini, Luciana Teresa Dias; Carlos, Iracilda Zeppone; Carrilho, Emanuel

    2017-09-05

    This study presents an inexpensive and easy way to produce a microfluidic device that mimics a blood vessel, serving as a start point for cell culture under perfusion, cardiovascular research, and toxicological studies. Endpoint assays (i.e., MTT reduction and NO assays) were used and revealed that the components making up the microchip, which is made of polyester and toner (PT), did not induce cell death or nitric oxide (NO) production. Applying oxygen plasma and fibronectin improved the adhesion and proliferation endothelial cell along the microchannel. As expected, these treatments showed an increase in vascular endothelial growth factor (VEGF-A) concentration profiles, which is correlated with adherence and cell proliferation, thus promoting endothelialization of the device for neovascularization. Regardless the simplicity of the device, our "vein-on-a-chip" mimetic has a potential to serve as a powerful tool for those that demand a rapid microfabrication method in cell biology or organ-on-a-chip research.

  19. 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.

  20. A pump-free microfluidic 3D perfusion platform for the efficient differentiation of human hepatocyte-like cells.

    PubMed

    Ong, Louis Jun Ye; Chong, Lor Huai; Jin, Lin; Singh, Pawan Kumar; Lee, Poh Seng; Yu, Hanry; Ananthanarayanan, Abhishek; Leo, Hwa Liang; Toh, Yi-Chin

    2017-10-01

    The practical application of microfluidic liver models for in vitro drug testing is partly hampered by their reliance on human primary hepatocytes, which are limited in number and have batch-to-batch variation. Human stem cell-derived hepatocytes offer an attractive alternative cell source, although their 3D differentiation and maturation in a microfluidic platform have not yet been demonstrated. We develop a pump-free microfluidic 3D perfusion platform to achieve long-term and efficient differentiation of human liver progenitor cells into hepatocyte-like cells (HLCs). The device contains a micropillar array to immobilize cells three-dimensionally in a central cell culture compartment flanked by two side perfusion channels. Constant pump-free medium perfusion is accomplished by controlling the differential heights of horizontally orientated inlet and outlet media reservoirs. Computational fluid dynamic simulation is used to estimate the hydrostatic pressure heads required to achieve different perfusion flow rates, which are experimentally validated by micro-particle image velocimetry, as well as viability and functional assessments in a primary rat hepatocyte model. We perform on-chip differentiation of HepaRG, a human bipotent progenitor cell, and discover that 3D microperfusion greatly enhances the hepatocyte differentiation efficiency over static 2D and 3D cultures. However, HepaRG progenitor cells are highly sensitive to the time-point at which microperfusion is applied. Isolated HepaRG cells that are primed as static 3D spheroids before being subjected to microperfusion yield a significantly higher proportion of HLCs (92%) than direct microperfusion of isolated HepaRG cells (62%). This platform potentially offers a simple and efficient means to develop highly functional microfluidic liver models incorporating human stem cell-derived HLCs. Biotechnol. Bioeng. 2017;114: 2360-2370. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. A palmtop-sized microfluidic cell culture system driven by a miniaturized infusion pump.

    PubMed

    Sasaki, Naoki; Shinjo, Mika; Hirakawa, Satoshi; Nishinaka, Masahiro; Tanaka, Yo; Mawatari, Kazuma; Kitamori, Takehiko; Sato, Kae

    2012-07-01

    A palmtop-sized microfluidic cell culture system is presented. The system consists of a microfluidic device and a miniaturized infusion pump that possesses a reservoir of culture medium, an electrical control circuit, and an internal battery. The footprint of the system was downsized to 87 × 57 mm, which is, to the best of our knowledge, the smallest integrated cell culture system. Immortalized human microvascular endothelial cells (HMEC-1) and human umbilical vein endothelial cells (HUVEC) were cultured in the system. HMEC-1 in the system proliferated at the same speed as cells in a microchannel perfused by a syringe pump and cells in a culture flask. HUVEC in the system oriented along the direction of the fluid flow. Claudin-5, a tight junction protein, was localized along the peripheries of the HUVEC. We expect that the present system is applicable to various cell types as a stand-alone and easy-to-use system for microfluidic bioanalysis.

  2. A disposable and multifunctional capsule for easy operation of microfluidic elastomer systems

    NASA Astrophysics Data System (ADS)

    Thorslund, Sara; Nguyen, Hugo; Läräng, Thomas; Barkefors, Irmeli; Kreuger, Johan

    2011-12-01

    The global lab-on-chip and microfluidic markets for cell-based assays have been predicted to grow considerably, as novel microfluidic systems enable cell biologists to perform in vitro experiments at an unprecedented level of experimental control. Nevertheless, microfluidic assays must, in order to compete with conventional assays, be made available at easily affordable costs, and in addition be made simple to operate for users having no previous experience with microfluidics. We have to this end developed a multifunctional microfluidic capsule that can be mass-produced at low cost in thermoplastic material. The capsule enables straightforward operation of elastomer inserts of optional design, here exemplified with insert designs for molecular gradient formation in microfluidic cell culture systems. The integrated macro-micro interface of the capsule ensures reliable connection of the elastomer fluidic structures to an external perfusion system. A separate compartment in the capsule filled with superabsorbent material is used for internal waste absorption. The capsule assembly process is made easy by integrated snap-fits, and samples within the closed capsule can be analyzed using both inverted and upright microscopes. Taken together, the capsule concept presented here could help accelerate the use of microfluidic-based biological assays in the life science sector.

  3. Polymer-based platform for microfluidic systems

    DOEpatents

    Benett, William [Livermore, CA; Krulevitch, Peter [Pleasanton, CA; Maghribi, Mariam [Livermore, CA; Hamilton, Julie [Tracy, CA; Rose, Klint [Boston, MA; Wang, Amy W [Oakland, CA

    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.

  4. Acoustically-driven microfluidic systems

    SciTech Connect

    Wang, A W; Benett, W J; Tarte, L R

    2000-06-23

    We have demonstrated a non-contact method of concentrating and mixing particles in a plastic microfluidic chamber employing acoustic radiation pressure. A flaw cell package has also been designed that integrates liquid sample interconnects, electrical contacts and a removable sample chamber. Experiments were performed on 1, 3, 6, and 10 {micro}m polystyrene beads. Increased antibody binding to a solid-phase substrate was observed in the presence of acoustic mixing due to improve mass transport.

  5. Microfluidic systems for single DNA dynamics

    PubMed Central

    Mai, Danielle J.; Brockman, Christopher

    2012-01-01

    Recent advances in microfluidics have enabled the molecular-level study of polymer dynamics using single DNA chains. Single polymer studies based on fluorescence microscopy allow for the direct observation of non-equilibrium polymer conformations and dynamical phenomena such as diffusion, relaxation, and molecular stretching pathways in flow. Microfluidic devices have enabled the precise control of model flow fields to study the non-equilibrium dynamics of soft materials, with device geometries including curved channels, cross-slots, and microfabricated obstacles and structures. This review explores recent microfluidic systems that have advanced the study of single polymer dynamics, while identifying new directions in the field that will further elucidate the relationship between polymer microstructure and bulk rheological properties. PMID:23139700

  6. Complex Microfluidic Systems Architectures and Applications to Micropower Generation

    DTIC Science & Technology

    2010-07-07

    Complex Microfluidic Systems Architectures and Applications to Micropower Generation” AFOSR grant FA9550-08-1-0345 Integrated Fluidics, Santa...reliability of components and the size of the system built up from such components. We advanced a novel microfluidic concept, named µfCPU, the Microfluidic ...Central Processing Unit, where the key microfluidic operations are performed within a single enclosure, using active, software-based inputs rather

  7. A microfluidic system for automatic cell culture

    NASA Astrophysics Data System (ADS)

    Huang, Chun-Wei; Lee, Gwo-Bin

    2007-07-01

    This study presents a new chip capable of automating the cell culture process by using microfluidic technology. This microfluidic cell culture system comprising microheaters, a micro temperature sensor, micropumps, microvalves, microchannels, a cell culture area and several reservoirs was fabricated by using micro-electro-mechanical-systems' fabrication processes. Traditional manual cell culture processes can be performed on this chip. A uni-directional pneumatic micropump was developed to transport the culture reagents and constraint the solutions to flow only in one direction, safeguarding the entire culture process from contamination. A new micro check valve was also used to prevent the culture solutions from flowing back into the microchannels. The microheaters and the micro temperature sensor were used to maintain a constant temperature during the cell culturing process. The pH value suitable for cell growth was also regulated during the cell culture process. A typical cell culturing process for human lung cancer cells (A549) was successfully performed to demonstrate the capability of the developed microfluidic system. This automatic cell culturing system can be eventually integrated with subsequent microfluidic modules for cell purification, collection, counting and lysis to form a cell-based micro-total-analysis system. Preliminary results have been presented in The Asia-Pacific Conference of Transducers and Micro-Nano Technology (APCOT), 25-28 June 2006

  8. Microfluidic enzymatic biosensing systems: A review.

    PubMed

    Mross, Stefan; Pierrat, Sebastien; Zimmermann, Tom; Kraft, Michael

    2015-08-15

    Microfluidic biosensing systems with enzyme-based detection have been extensively studied in the last years owing to features such as high specificity, a broad range of analytes and a high degree of automation. This review gives an overview of the most important factors associated with these systems. In the first part, frequently used immobilization protocols such as physisorption and covalent bonding and detection techniques such as amperometry and fluorescence measurements are discussed with respect to effort, lifetime and measurement range. The Michaelis-Menten model describing the kinetics of enzymatic reactions, the role of redox mediators and the limitations of the linear measurement range of enzymatic sensors are introduced. Several possibilities of extending the linear measurement range in microfluidic systems such as diffusion-limiting membranes and the flow injection setup are presented. Regarding the integration of enzymes into microfluidic systems during the fabrication process, the constraints imposed by the biomolecules due to the limited usage of high temperatures and solvents are addressed. In the second part, the most common forms of enzyme integration into microfluidic systems, i.e. in channels and on electrodes, on microparticles, on paper and thread and as injected enzyme solutions, are reviewed, focusing on fabrication, applications and performance. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Recent advances in microfluidic detection systems

    PubMed Central

    Baker, Christopher A; Duong, Cindy T; Grimley, Alix; Roper, Michael G

    2009-01-01

    There are numerous detection methods available for methods are being put to use for detection on these miniaturized systems, with the analyte of interest driving the choice of detection method. In this article, we summarize microfluidic 2 years. More focus is given to unconventional approaches to detection routes and novel strategies for performing high-sensitivity detection. PMID:20414455

  10. Nucleic acid amplification using microfluidic systems.

    PubMed

    Chang, Chen-Min; Chang, Wen-Hsin; Wang, Chih-Hung; Wang, Jung-Hao; Mai, John D; Lee, Gwo-Bin

    2013-04-07

    In the post-human-genome-project era, the development of molecular diagnostic techniques has advanced the frontiers of biomedical research. Nucleic-acid-based technology (NAT) plays an especially important role in molecular diagnosis. However, most research and clinical protocols still rely on the manual analysis of individual samples by skilled technicians which is a time-consuming and labor-intensive process. Recently, with advances in microfluidic designs, integrated micro total-analysis-systems have emerged to overcome the limitations of traditional detection assays. These microfluidic systems have the capability to rapidly perform experiments in parallel and with a high-throughput which allows a NAT analysis to be completed in a few hours or even a few minutes. These features have a significant beneficial influence on many aspects of traditional biological or biochemical research and this new technology is promising for improving molecular diagnosis. Thus, in the foreseeable future, microfluidic systems developed for molecular diagnosis using NAT will become an important tool in clinical diagnosis. One of the critical issues for NAT is nucleic acid amplification. In this review article, recent advances in nucleic acid amplification techniques using microfluidic systems will be reviewed. Different approaches for fast amplification of nucleic acids for molecular diagnosis will be highlighted.

  11. Cardiac tissue engineering using perfusion bioreactor systems

    PubMed Central

    Radisic, Milica; Marsano, Anna; Maidhof, Robert; Wang, Yadong; Vunjak-Novakovic, Gordana

    2009-01-01

    This protocol describes tissue engineering of synchronously contractile cardiac constructs by culturing cardiac cell populations on porous scaffolds (in some cases with an array of channels) and bioreactors with perfusion of culture medium (in some cases supplemented with an oxygen carrier). The overall approach is ‘biomimetic’ in nature as it tends to provide in vivo-like oxygen supply to cultured cells and thereby overcome inherent limitations of diffusional transport in conventional culture systems. In order to mimic the capillary network, cells are cultured on channeled elastomer scaffolds that are perfused with culture medium that can contain oxygen carriers. The overall protocol takes 2–4 weeks, including assembly of the perfusion systems, preparation of scaffolds, cell seeding and cultivation, and on-line and end-point assessment methods. This model is well suited for a wide range of cardiac tissue engineering applications, including the use of human stem cells, and high-fidelity models for biological research. PMID:18388955

  12. 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

  13. [An automatic system controlled by microcontroller for carotid sinus perfusion].

    PubMed

    Yi, X L; Wang, M Y; Fan, Z Z; He, R R

    2001-08-01

    To establish a new method for controlling automatically the carotid perfusion pressure. A cheap practical automatic perfusion unit based on AT89C2051 micro controller was designed. The unit, LDB-M perfusion pump and the carotid sinus of an animal constituted an automatic perfusion system. This system was able to provide ramp and stepwise updown perfusion pattern and has been used in the research of baroreflex. It can insure the precision and reproducibility of perfusion pressure curve, and improve the technical level in corresponding medical field.

  14. 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.

  15. Microfluidic Biosensing Systems Using Magnetic Nanoparticles

    PubMed Central

    Giouroudi, Ioanna; Keplinger, Franz

    2013-01-01

    In recent years, there has been rapidly growing interest in developing hand held, sensitive and cost-effective on-chip biosensing systems that directly translate the presence of certain bioanalytes (e.g., biomolecules, cells and viruses) into an electronic signal. The impressive and rapid progress in micro- and nanotechnology as well as in biotechnology enables the integration of a variety of analytical functions in a single chip. All necessary sample handling and analysis steps are then performed within the chip. Microfluidic systems for biomedical analysis usually consist of a set of units, which guarantees the manipulation, detection and recognition of bioanalytes in a reliable and flexible manner. Additionally, the use of magnetic fields for performing the aforementioned tasks has been steadily gaining interest. This is because magnetic fields can be well tuned and applied either externally or from a directly integrated solution in the biosensing system. In combination with these applied magnetic fields, magnetic nanoparticles are utilized. Some of the merits of magnetic nanoparticles are the possibility of manipulating them inside microfluidic channels by utilizing high gradient magnetic fields, their detection by integrated magnetic microsensors, and their flexibility due to functionalization by means of surface modification and specific binding. Their multi-functionality is what makes them ideal candidates as the active component in miniaturized on-chip biosensing systems. In this review, focus will be given to the type of biosening systems that use microfluidics in combination with magnetoresistive sensors and detect the presence of bioanalyte tagged with magnetic nanoparticles. PMID:24022689

  16. Microfluidic biosensing systems using magnetic nanoparticles.

    PubMed

    Giouroudi, Ioanna; Keplinger, Franz

    2013-09-09

    In recent years, there has been rapidly growing interest in developing hand held, sensitive and cost-effective on-chip biosensing systems that directly translate the presence of certain bioanalytes (e.g., biomolecules, cells and viruses) into an electronic signal. The impressive and rapid progress in micro- and nanotechnology as well as in biotechnology enables the integration of a variety of analytical functions in a single chip. All necessary sample handling and analysis steps are then performed within the chip. Microfluidic systems for biomedical analysis usually consist of a set of units, which guarantees the manipulation, detection and recognition of bioanalytes in a reliable and flexible manner. Additionally, the use of magnetic fields for performing the aforementioned tasks has been steadily gaining interest. This is because magnetic fields can be well tuned and applied either externally or from a directly integrated solution in the biosensing system. In combination with these applied magnetic fields, magnetic nanoparticles are utilized. Some of the merits of magnetic nanoparticles are the possibility of manipulating them inside microfluidic channels by utilizing high gradient magnetic fields, their detection by integrated magnetic microsensors, and their flexibility due to functionalization by means of surface modification and specific binding. Their multi-functionality is what makes them ideal candidates as the active component in miniaturized on-chip biosensing systems. In this review, focus will be given to the type of biosening systems that use microfluidics in combination with magnetoresistive sensors and detect the presence of bioanalyte tagged with magnetic nanoparticles.

  17. Inner ear drug delivery via a reciprocating perfusion system in the guinea pig

    PubMed Central

    Chen, Zhiqiang; Kujawa, Sharon G.; McKenna, Michael J.; Fiering, Jason O.; Mescher, Mark J.; Borenstein, Jeffrey T.; Leary Swan, Erin E.; Sewell, William F.

    2007-01-01

    Rapid progress in understanding the molecular mechanisms associated with cochlear and auditory nerve degenerative processes offers hope for the development of gene-transfer and molecular approaches to treat these diseases in patients. For therapies based on these discoveries to become clinically useful, it will be necessary to develop safe and reliable mechanisms for the delivery of drugs into the inner ear, bypassing the blood–labyrinthine barrier. Toward the goal of developing an inner ear perfusion device for human use, a reciprocating microfluidic system that allows perfusion of drugs into the cochlear perilymph through a single inlet hole in scala tympani of the basal turn was developed. The performance of a prototype, extracorporeal reciprocating perfusion system in guinea pigs is described. Analysis of the cochlear distribution of compounds after perfusion took advantage of the place-dependent generation of responses to tones along the length of the cochlea. Perfusion with a control artificial perilymph solution had no effect. Two drugs with well-characterized effects on cochlear physiology, salicylate (5 mM) and DNQX (6,7-Dinitroquinoxaline-2,3-dione; 100 and 300 μM), reversibly altered responses. The magnitude of drug effect decreased with distance from the perfusion pipette for up to 10 mm, and increased with dose and length of application. PMID:16274830

  18. A capillary valve for microfluidic systems.

    SciTech Connect

    Cummings, Eric B.; Kanouff, Michael P.; Rush, Brian M.

    2004-10-01

    Microfluidic systems are becoming increasingly complicated as the number of applications grows. The use of microfluidic systems for chemical and biological agent detection, for example, requires that a given sample be subjected to many process steps, which requires microvalves to control the position and transport of the sample. Each microfluidic application has its own specific valve requirements and this has precipitated the wide variety of valve designs reported in the literature. Each of these valve designs has its strengths and weaknesses. The strength of the valve design proposed here is its simplicity, which makes it easy to fabricate, easy to actuate, and easy to integrate with a microfluidic system. It can be applied to either gas phase or liquid phase systems. This novel design uses a secondary fluid to stop the flow of the primary fluid in the system. The secondary fluid must be chosen based on the type of flow that it must stop. A dielectric fluid must be used for a liquid phase flow driven by electroosmosis, and a liquid with a large surface tension should be used to stop a gas phase flow driven by a weak pressure differential. Experiments were carried out investigating certain critical functions of the design. These experiments verified that the secondary fluid can be reversibly moved between its 'valve opened' and 'valve closed' positions, where the secondary fluid remained as one contiguous piece during this transport process. The experiments also verified that when Fluorinert is used as the secondary fluid, the valve can break an electric circuit. It was found necessary to apply a hydrophobic coating to the microchannels to stop the primary fluid, an aqueous electrolyte, from wicking past the Fluorinert and short-circuiting the valve. A simple model was used to develop valve designs that could be closed using an electrokinetic pump, and re-opened by simply turning the pump off and allowing capillary forces to push the secondary fluid back into its

  19. Fluid delivery manifolds and microfluidic systems

    DOEpatents

    Renzi, Ronald F.; Sommer, Gregory J.; Singh, Anup K.; Hatch, Anson V.; Claudnic, Mark R.; Wang, Ying-Chih; Van de Vreugde, James L.

    2017-02-28

    Embodiments of fluid distribution manifolds, cartridges, and microfluidic systems are described herein. Fluid distribution manifolds may include an insert member and a manifold base and may define a substantially closed channel within the manifold when the insert member is press-fit into the base. Cartridges described herein may allow for simultaneous electrical and fluidic interconnection with an electrical multiplex board and may be held in place using magnetic attraction.

  20. Electrostatic actuators for portable microfluidic systems

    NASA Astrophysics Data System (ADS)

    Tice, Joshua

    Both developed and developing nations have an urgent need to diagnose disease cheaply, reliably, and independently of centralized facilities. Microfulidic platforms are well-positioned to address the need for portable diagnostics, mainly due to their obvious advantage in size. However, most microfluidic methods rely on equipment outside of the chip either for driving fluid flow (e.g., syringe pumps) or for taking measurements (e.g., lasers or microscopes). The energy and space requirements of the whole system inhibit portability and contribute to costs. To capitalize on the strengths of microfluidic platforms and address the serious needs of society, system components need to be miniaturized. Also, miniaturization should be accomplished as simply as possible, considering that simplicity is usually requisite for achieving truly transformative technology. Herein, I attempt to address the issue of controlling fluid flow in portable microfluidic systems. I focus on systems that are driven by elastomer-based membrane valves, since these valves are inherently simple, yet they are capable of sophisticated fluid manipulation. Others have attempted to modify pneumatic microvalves for portable applications, e.g., by transitioning to electromagnetic, thermopneumatic, or piezoelectric actuation principles. However, none of these strategies maintain the proper balance of simplicity, functionality, and ease of integration. My research centers on electrostatic actuators, due to their conceptual simplicity and the efficacy of electrostatic forces on the microscale. To ensure easy integration with polymer-based systems, and to maintain simplicity in the fabrication procedure, the actuators were constructed solely from poly(dimethylsiloxane) and multi-walled carbon nanotubes. In addition, the actuators were fabricated exclusively with soft-lithographic techniques. A mathematical model was developed to identify actuator parameters compatible with soft-lithography, and also to

  1. 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.

  2. Microfluidics and Coagulation Biology

    PubMed Central

    Colace, Thomas V.; Tormoen, Garth W.

    2014-01-01

    The study of blood ex vivo can occur in closed or open systems, with or without flow. Microfluidic devices facilitate measurements of platelet function, coagulation biology, cellular biorheology, adhesion dynamics, pharmacology, and clinical diagnostics. An experimental session can accommodate 100s to 1000s of unique clotting events. Using microfluidics, thrombotic events can be studied on defined surfaces of biopolymers, matrix proteins, and tissue factor under constant flow rate or constant pressure drop conditions. Distinct shear rates can be created on a device with a single perfusion pump. Microfluidic devices facilitated the determination of intraluminal thrombus permeability and the discovery that platelet contractility can be activated by a sudden decrease in flow. Microfluidics are ideal for multicolor imaging of platelets, fibrin, and phosphatidylserine and provide a human blood analog to the mouse injury models. Overall, microfluidic advances offer many opportunities for research, drug testing under relevant hemodynamic conditions, and clinical diagnostics. PMID:23642241

  3. 3D functional and perfusable microvascular networks for organotypic microfluidic models.

    PubMed

    Bersini, Simone; Moretti, Matteo

    2015-05-01

    The metastatic dissemination of cancer cells from primary tumors to secondary loci is a complex and multistep process including local invasion, intravasation, survival in the blood stream and extravasation towards the metastatic site. It is well known cancer metastases follow organ-specific pathways with selected primary tumors mainly metastasizing towards a specific panel of secondary organs (Steven Paget's theory 1889). However, circulatory patterns and microarchitecture of capillary networks play a key role in the metastatic spread as well (James Ewing's theory 1929). Taking into account both these factors would be critical to develop more complex and physiologically relevant in vitro cancer models. This review presents recent advances in the generation of microvascularized systems through microfluidic approaches and discusses promising results achieved by organ-on-a-chip platforms mimicking the pathophysiology of the functional units of specific organs. The combination of physiologically-like microvascular networks and organotypic microenvironments would foster a new generation of in vitro cancer models to more effectively screen new therapeutics, design personalized medicine treatments and investigate molecular pathways involved in cancer metastases.

  4. Real-time monitoring system for microfluidics

    NASA Astrophysics Data System (ADS)

    Sapuppo, F.; Cantelli, G.; Fortuna, L.; Arena, P.; Bucolo, M.

    2007-05-01

    A new non-invasive real-time system for the monitoring and control of microfluidodynamic phenomena is proposed. The general purpose design of such system is suitable for in vitro and in vivo experimental setup and therefore for microfluidic application in the biomedical field such as lab-on-chip and for research studies in the field of microcirculation. The system consists of an ad hoc optical setup for image magnification providing images suitable for image acquisition and processing. The optic system was designed and developed using discrete opto-mechanic components mounted on a breadboard in order to provide an optic path accessible at any point where the information needs to be acquired. The optic sensing, acquisition, and processing were performed using an integrated vision system based on the Cellular Nonlinear Networks (CNNs) analogic technology called Focal Plane Processor (FPP, Eye-RIS, Anafocus) and inserted in the optic path. Ad hoc algorithms were implemented for the real-time analysis and extraction of fluido-dynamic parameters in micro-channels. They were tested on images recorded during in vivo microcirculation experiments on hamsters and then they were applied on images optically acquired and processed in real-time during in vitro experiments on a continuous microfluidic device (serpentine mixer, ThinXXS) with a two-phase fluid.

  5. Microfluidic assay of platelet deposition on collagen by perfusion of whole blood from healthy individuals taking aspirin.

    PubMed

    Li, Ruizhi; Fries, Susanne; Li, Xuanwen; Grosser, Tilo; Diamond, Scott L

    2013-08-01

    Microfluidic devices can create hemodynamic conditions for platelet assays. We validated an 8-channel device in a study of interdonor response to acetylsalicylic acid (ASA, aspirin) with whole blood from 28 healthy individuals. Platelet deposition was assessed before treatment or 24 h after ingestion of 325 mg ASA. Whole blood (plus 100 μmol/L H-d-Phe-Pro-Arg-chloromethylketone to inhibit thrombin) was further treated ex vivo with ASA (0-500 μmol/L) and perfused over fibrillar collagen for 300 s at a venous wall shear rate (200 s(-1)). Ex vivo ASA addition to blood drawn before aspirin ingestion caused a reduction in platelet deposition [half-maximal inhibitory concentration (IC50) approximately 10-20 μmol/L], especially between 150 and 300 s of perfusion, when secondary aggregation mediated by thromboxane was expected. Twenty-seven of 28 individuals displayed smaller deposits (45% mean reduction; range 10%-90%; P < 0.001) from blood obtained 24 h after ASA ingestion (no ASA added ex vivo). In replicate tests, an R value to score secondary aggregation [deposition rate from 150 to 300 s normalized by rate from 60 to 150 s] showed R < 1 in only 2 of 28 individuals without ASA ingestion, with R > 1 in only 3 of 28 individuals after 500 μmol/L ASA addition ex vivo. At 24 h after ASA ingestion, 21 of 28 individuals displayed poor secondary aggregation (R < 1) without ex vivo ASA addition, whereas the 7 individuals with residual secondary aggregation (R > 1) displayed insensitivity to ex vivo ASA addition. Platelet deposition was not correlated with platelet count. Ex vivo ASA addition caused similar inhibition at venous and arterial wall shear rates. Microfluidic devices quantified platelet deposition after ingestion or ex vivo addition of aspirin.

  6. Droplet position control in digital microfluidic systems.

    PubMed

    Bhattacharjee, Biddut; Najjaran, Homayoun

    2010-02-01

    Research on so called digital microfluidic systems (DMS) capable of manipulating individual microdroplets on a cell-based structure has enormously increased in the past few years, mainly due to the demand of the technology-dependent biomedical applications. Significant research in this area has been related to the simulation and modeling of droplet motion, demonstration of different drop actuation techniques on laboratory-scale prototypes, and droplet routing and scheduling for more efficient assay procedures. This paper introduces the basics of the control analysis and design of a DMS, which is a relatively unexplored area in digital microfluidics. This paper starts with a discussion on a simplified dynamic model of droplet motion in a planar array of cells, and continues with more complicated dynamic models that are necessary to realize the structure of an appropriate closed-loop control system for the DMS. The control analysis and design includes both the transient and steady-state responses of the DMS under external driving forces. The proposed control analysis and design approach is implemented into SIMULINK models to demonstrate the performance of the DMS through simulation using the system parameters previously reported in the literature.

  7. Screening of aptamers on microfluidic systems for clinical applications.

    PubMed

    Weng, Chen-Hsun; Huang, Chao-Jyun; Lee, Gwo-Bin

    2012-01-01

    The use of microfluidic systems for screening of aptamers and their biomedical applications are reviewed in this paper. Aptamers with different nucleic acid sequences have been extensively studied and the results demonstrated a strong binding affinity to target molecules such that they can be used as promising candidate biomarkers for diagnosis and therapeutics. Recently, the aptamer screening protocol has been conducted with microfluidic-based devices. Furthermore, aptamer affinity screening by a microfluidic-based method has demonstrated remarkable advantages over competing traditional methods. In this paper, we first reviewed microfluidic systems which demonstrated efficient and rapid screening of a specific aptamer. Then, the clinical applications of screened aptamers, also performed by microfluidic systems, are further reviewed. These automated microfluidic systems can provide advantages over their conventional counterparts including more compactness, faster analysis, less sample/reagent consumption and automation. An aptamer-based compact microfluidic system for diagnosis may even lead to a point-of-care device. The use of microfluidic systems for aptamer screening and diagnosis is expected to continue growing in the near future and may make a substantial impact on biomedical applications.

  8. Autonomous microfluidic system for phosphate detection.

    PubMed

    McGraw, Christina M; Stitzel, Shannon E; Cleary, John; Slater, Conor; Diamond, Dermot

    2007-02-28

    Miniaturization of analytical devices through the advent of microfluidics and micro total analysis systems is an important step forward for applications such as medical diagnostics and environmental monitoring. The development of field-deployable instruments requires that the entire system, including all necessary peripheral components, be miniaturized and packaged in a portable device. A sensor for long-term monitoring of phosphate levels has been developed that incorporates sampling, reagent and waste storage, detection, and wireless communication into a complete, miniaturized system. The device employs a low-power detection and communication system, so the entire instrument can operate autonomously for 7 days on a single rechargeable, 12V battery. In addition, integration of a wireless communication device allows the instrument to be controlled and results to be downloaded remotely. This autonomous system has a limit of detection of 0.3mg/L and a linear dynamic range between 0 and 20mg/L.

  9. Integrated Multi-process Microfluidic Systems for Automating Analysis

    PubMed Central

    Yang, Weichun; Woolley, Adam T.

    2010-01-01

    Microfluidic technologies have been applied extensively in rapid sample analysis. Some current challenges for standard microfluidic systems are relatively high detection limits, and reduced resolving power and peak capacity compared to conventional approaches. The integration of multiple functions and components onto a single platform can overcome these separation and detection limitations of microfluidics. Multiplexed systems can greatly increase peak capacity in multidimensional separations and can increase sample throughput by analyzing many samples simultaneously. On-chip sample preparation, including labeling, preconcentration, cleanup and amplification, can all serve to speed up and automate processes in integrated microfluidic systems. This paper summarizes advances in integrated multi-process microfluidic systems for automated analysis, their benefits and areas for needed improvement. PMID:20514343

  10. Imaging of oxygen in microreactors and microfluidic systems

    NASA Astrophysics Data System (ADS)

    Sun, Shiwen; Ungerböck, Birgit; Mayr, Torsten

    2015-09-01

    This review gives an overview on the state-of-the-art of oxygen imaging in microfluidics. Oxygen imaging using optical oxygen sensors based on luminescence is a versatile and powerful tool for obtaining profoundly space-resolved information of oxygen in microreactors and microfluidic systems. We briefly introduce the principle of oxygen imaging and present techniques of oxygen imaging applied in microreactors and microfluidic devices, including selection criteria and demands of sensing material and basic set-up for a 2D oxygen sensing system. A detailed review of oxygen imaging in microreactors and microfluidic systems is given on different applications in oxygen gradient monitoring, cell culturing, single-cell analysis and chemical reactions. Finally, we discuss challenges and trends of oxygen imaging in microfluidic systems.

  11. Microfluidics-Enabled Diagnostic Systems: Markets, Challenges, and Examples.

    PubMed

    Becker, Holger; Gärtner, Claudia

    2017-01-01

    Microfluidics has become an important tool for the commercial product development in diagnostics. This article will focus on current technical demands during the development process such as material and integration challenges. Furthermore, we present data on the diagnostics market as well as examples of microfluidics-enabled systems currently under commercial development or already on the market.

  12. Dynamical systems techniques for enhancing microfluidic mixing

    NASA Astrophysics Data System (ADS)

    Balasuriya, Sanjeeva

    2015-09-01

    Achieving rapid mixing is often desirable in microfluidic devices, for example in improving reation rates in biotechnological assays. Enhancing mixing within a particular context is often achieved by introducing problem-specific strategies such as grooved or twisted channels, ac electromagnetic fields or oscillatory microsyringe flows. Evaluating the efficiency of these methods is challenging since either experimental fabrication and sensing, or computationally expensive direct numerical simulations with complicated boundary conditions, are required. A review of how mixing can be quantified when velocity fields have been obtained from such situations is presented. A less-known alternative to these methods is offered by dynamical systems, which characterizes the motion of collective fluid parcel trajectories by studying crucial interior flow barriers which move unsteadily, but nevertheless strongly govern mixing possibilities. The methodology behind defining these barriers and quantifying the fluid transport influenced by them is explained. Their application towards several microfluidic situations (e.g. best cross-flow positioning in cross-channel micromixers, usage of channel curvature to enhance mixing within microdroplets traveling in a channel, optimum frequencies of velocity agitations to use) is discussed.

  13. Integrated microfluidic systems for DNA analysis.

    PubMed

    Njoroge, Samuel K; Chen, Hui-Wen; Witek, Małgorzata A; Soper, Steven A

    2011-01-01

    The potential utility of genome-related research in terms of evolving basic discoveries in biology has generated widespread use of DNA diagnostics and DNA forensics and driven the accelerated development of fully integrated microfluidic systems for genome processing. To produce a microsystem with favorable performance characteristics for genetic-based analyses, several key operational elements must be strategically chosen, including device substrate material, temperature control, fluidic control, and reaction product readout. As a matter of definition, a microdevice is a chip that performs a single processing step, for example microchip electrophoresis. Several microdevices can be integrated to a single wafer, or combined on a control board as separate devices to form a microsystem. A microsystem is defined as a chip composed of at least two microdevices. Among the many documented analytical microdevices, those focused on the ability to perform the polymerase chain reaction (PCR) have been reported extensively due to the importance of this processing step in most genetic-based assays. Other microdevices that have been detailed in the literature include those for solid-phase extractions, microchip electrophoresis, and devices composed of DNA microarrays used for interrogating DNA primary structure. Great progress has also been made in the areas of chip fabrication, bonding and sealing to enclose fluidic networks, evaluation of different chip substrate materials, surface chemistries, and the architecture of reaction conduits for basic processing steps such as mixing. Other important elements that have been developed to realize functional systems include miniaturized readout formats comprising optical or electrochemical transduction and interconnect technologies. These discoveries have led to the development of fully autonomous and functional integrated systems for genome processing that can supply "sample in/answer out" capabilities. In this chapter, we focus on

  14. Microfluidic process monitor for industrial solvent extraction system

    SciTech Connect

    Gelis, Artem; Pereira, Candido; Nichols, Kevin Paul Flood

    2016-01-12

    The present invention provides a system for solvent extraction utilizing a first electrode with a raised area formed on its surface, which defines a portion of a microfluidic channel; a second electrode with a flat surface, defining another portion of the microfluidic channel that opposes the raised area of the first electrode; a reversibly deformable substrate disposed between the first electrode and second electrode, adapted to accommodate the raised area of the first electrode and having a portion that extends beyond the raised area of the first electrode, that portion defining the remaining portions of the microfluidic channel; and an electrolyte of at least two immiscible liquids that flows through the microfluidic channel. Also provided is a system for performing multiple solvent extractions utilizing several microfluidic chips or unit operations connected in series.

  15. Dynamics of Ceramide Channels Detected Using a Microfluidic System

    PubMed Central

    DeVoe, Don L.; Colombini, Marco

    2012-01-01

    Ceramide, a proapoptotic sphingolipid, has been shown to form channels, in mitochondrial outer membranes, large enough to translocate proteins. In phospholipid membranes, electrophysiological studies and electron microscopic visualization both report that these channels form in a range of sizes with a modal value of 10 nm in diameter. A hydrogen bonded barrel-like structure consisting of hundreds of ceramide molecules has been proposed for the structure of the channel and this is supported by electrophysiological studies and molecular dynamic simulations. To our knowledge, the mechanical strength and deformability of such a large diameter but extremely thin cylindrical structure has never been reported. Here we present evidence for a reversible mechanical distortion of the cylinder following the addition of La3+. A microfluidic system was used to repeatedly lower and then restore the conductance by alternatively perfusing La3+ and EDTA. Although aspects of the kinetics of conductance drop and recovery are consistent with a disassembly/diffusion/reassembly model, others are inconsistent with the expected time scale of lateral diffusion of disassembled channel fragments in the membrane. The presence of a residual conductance following La3+ treatment and the relationship between the residual conductance and the initial conductance were both indicative of a distortion/recovery process in analogy with a pressure-induced distortion of a flexible cylinder. PMID:22984432

  16. 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

  17. Accessing new chemical entities through microfluidic systems.

    PubMed

    Rodrigues, Tiago; Schneider, Petra; Schneider, Gisbert

    2014-06-02

    Flow systems have been successfully utilized for a wide variety of applications in chemical research and development, including the miniaturization of (bio)analytical methods and synthetic (bio)organic chemistry. Currently, we are witnessing the growing use of microfluidic technologies for the discovery of new chemical entities. As a consequence, chemical biology and molecular medicine research are being reshaped by this technique. In this Minireview we portray the state-of-the-art, including the most recent advances in the application of microchip reactors as well as the micro- and mesoscale coil reactor-assisted synthesis of bioactive small molecules, and forecast the potential future use of this promising technology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Sample preparation system for microfluidic applications

    DOEpatents

    Mosier, Bruce P.; Crocker, Robert W.; Patel, Kamlesh D.; Harnett, Cindy K.

    2007-05-08

    An apparatus that couples automated injection with flow feedback to provide nanoliter accuracy in controlling microliter volumes. The apparatus comprises generally a source of hydraulic fluid pressure, a fluid isolator joined to the outlet of the hydraulic pressure source and a flow sensor to provide pressure-driven analyte metering. For operation generally and particularly in microfluidic systems the hydraulic pressure source is typically an electrokinetic (EK) pump that incorporates gasless electrodes. The apparatus is capable of metering sub-microliter volumes at flowrates of 1 100 .mu.L/min into microsystem load pressures of up to 1000 50 psi, respectively. Flowrates can be specified within 0.5 .mu.L/min and volumes as small as 80 nL can be metered.

  19. Single cell microfluidics for systems oncology

    NASA Astrophysics Data System (ADS)

    Fan, Rong

    2012-02-01

    The singular term ``cancer'' is never one kind of disease, but deceivingly encompasses a large number of heterogeneous disease states, which makes it impossible to completely treat cancer using a generic approach. Rather systems approaches are urgently required to assess cancer heterogeneity, stratify patients and enable the most effective, individualized treatment. The heterogeneity of tumors at the single cell level is reflected by the hierarchical complexity of the tumor microenvironment. To identify all the cellular components, including both tumor and infiltrating immune cells, and to delineate the associated cell-to-cell signaling network that dictates tumor initiation, progression and metastasis, we developed a single cell microfluidics chip that can analyze a panel of proteins that are potentially associated inter-cellular signaling network in tumor microenvironment from hundreds of single cells in parallel. This platform integrates two advanced technologies -- microfluidic single cell handling and ultra-high density protein array. This device was first tested for highly multiplexed profiling of secreted proteins including tumor-immune signaling molecules from monocytic leukemia cells. We observed profound cellular heterogeneity with all functional phenotypes quantitatively identified. Correlation analysis further indicated the existence of an intercellular cytokine network in which TNFα-induced secondary signaling cascades further increased functional cellular diversity. It was also exploited to evaluate polyfunctionality of tumor antigen-specific T cells from melanoma patients being treated with adoptive T cell transfer immunotherapy. This platform could be further extended to analyze both solid tumor cells (e.g. human lung carcinoma cells) and infiltrating immune cells (e.g. macrophages) so as to enable systems analysis of the complex tumor microenvironment from small amounts of clinical specimens, e.g. skinny needle biopsies. Thus, it could potentially

  20. A microfluidic gas damper for stabilizing gas pressure in portable microfluidic systems.

    PubMed

    Zhang, Xinjie; Zhu, Zhixian; Xiang, Nan; Ni, Zhonghua

    2016-09-01

    Pressure fluctuations, which invariably occur in microfluidic systems, usually result in the unstable fluid delivery in microfluidic channels. In this work, a novel microfluidic gas damper is proposed and applied for providing stable fluid-driving pressures. Then, a pressure-driven flow setup is constructed to investigate the gas damping characteristics of our damper. Since the pressure-driven flow setup functions as a resistor-capacitor low-pass filter, the damper significantly decreases the amplitude of the input pressures via self-regulating its pneumatic resistance. In addition, the gas volume and pressure frequency are found to have direct effects on the pressure fluctuations. The practical application of the gas damper is examined through a portable pressure-driven system, which consists of an air blower, a gas damper, and a centrifuge tube. By periodically pressing the air blower, precise flow rates with low throughput (∼9.64 μl min(-1)) and high throughput (∼1367.15 μl min(-1)) are successfully delivered. Future integration of our microfluidic gas damper with miniaturized pressure generators (e.g., peristaltic or pressure-driven micropumps) can fully exploit the potential of the gas damper for low-cost, portable microfluidics where stable pressures or flow rates are required.

  1. Multilayer-based lab-on-a-chip systems for perfused cell-based assays

    NASA Astrophysics Data System (ADS)

    Klotzbach, Udo; Sonntag, Frank; Grünzner, Stefan; Busek, Mathias; Schmieder, Florian; Franke, Volker

    2014-12-01

    A novel integrated technology chain of laser-microstructured multilayer foils for fast, flexible, and low-cost manufacturing of lab-on-a-chip devices especially for complex cell and tissue culture applications, which provides pulsatile fluid flow within physiological ranges at low media-to-cells ratio, was developed and established. Initially the microfluidic system is constructively divided into individual layers, which are formed by separate foils or plates. Based on the functional boundary conditions and the necessary properties of each layer, their corresponding foils and plates are chosen. In the third step, the foils and plates are laser microstructured and functionalized from both sides. In the fourth and last manufacturing step, the multiple plates and foils are joined using different bonding techniques like adhesive bonding, welding, etc. This multilayer technology together with pneumatically driven micropumps and valves permits the manufacturing of fluidic structures and perfusion systems, which spread out above multiple planes. Based on the established lab-on-a-chip platform for perfused cell-based assays, a multilayer microfluidic system with two parallel connected cell culture chambers was successfully implemented.

  2. Lattice Boltzmann Simulation of Particle Laden Flows in Microfluidic Systems

    DTIC Science & Technology

    2003-12-01

    wide application and will enable the study of colloidal/macromolecular transport in physiological systems, such as, blood filtration in the kidney... MICROFLUIDIC SYSTEMS DOE/Lawrence Livermore National Laboratory Sponsored by Defense Advanced Research Projects Agency DARPA Order No. E117...Jun 00 – Aug 02 4. TITLE AND SUBTITLE LATTICE BOLTZMANN SIMULATION OF PARTICLE LADEN FLOWS IN MICROFLUIDIC SYSTEMS 6. AUTHOR(S) David S

  3. Microfluidically supported biochip design for culture of endothelial cell layers with improved perfusion conditions.

    PubMed

    Raasch, Martin; Rennert, Knut; Jahn, Tobias; Peters, Sven; Henkel, Thomas; Huber, Otmar; Schulz, Ingo; Becker, Holger; Lorkowski, Stefan; Funke, Harald; Mosig, Alexander

    2015-03-02

    Hemodynamic forces generated by the blood flow are of central importance for the function of endothelial cells (ECs), which form a biologically active cellular monolayer in blood vessels and serve as a selective barrier for macromolecular permeability. Mechanical stimulation of the endothelial monolayer induces morphological remodeling in its cytoskeleton. For in vitro studies on EC biology culture devices are desirable that simulate conditions of flow in blood vessels and allow flow-based adhesion/permeability assays under optimal perfusion conditions. With this aim we designed a biochip comprising a perfusable membrane that serves as cell culture platform multi-organ-tissue-flow (MOTiF biochip). This biochip allows an effective supply with nutrition medium, discharge of catabolic cell metabolites and defined application of shear stress to ECs under laminar flow conditions. To characterize EC layers cultured in the MOTiF biochip we investigated cell viability, expression of EC marker proteins and cell adhesion molecules of ECs dynamically cultured under low and high shear stress, and compared them with an endothelial culture in established two-dimensionally perfused flow chambers and under static conditions. We show that ECs cultured in the MOTiF biochip form a tight EC monolayer with increased cellular density, enhanced cell layer thickness, presumably as the result of a rapid and effective adaption to shear stress by remodeling of the cytoskeleton. Moreover, endothelial layers in the MOTiF biochip express higher amounts of EC marker proteins von-Willebrand-factor and PECAM-1. EC layers were highly responsive to stimulation with TNFα as detected at the level of ICAM-1, VCAM-1 and E-selectin expression and modulation of endothelial permeability in response to TNFα/IFNγ treatment under flow conditions. Compared to static and two-dimensionally perfused cell culture condition we consider MOTiF biochips as a valuable tool for studying EC biology in vitro under

  4. The Groningen hypothermic liver perfusion pump: functional evaluation of a new machine perfusion system.

    PubMed

    van der Plaats, A; Maathuis, M H J; 'T Hart, N A; Bellekom, A A; Hofker, H S; van der Houwen, E B; Verkerke, G J; Leuvenink, H G D; Verdonck, P; Ploeg, R J; Rakhorst, G

    2006-12-01

    To improve preservation of donor livers, we have developed a portable hypothermic machine perfusion (HMP) system as an alternative for static cold storage. A prototype of the system was built and evaluated on functionality. Evaluation criteria included 24 h of adequate pressure controlled perfusion, sufficient oxygenation, a maintained 0-4 degrees C temperature and sterile conditions. Porcine livers were perfused with pump pressures that were set at 4 mmHg (continuous, portal vein) and 30/20 mmHg, at 60 BPM (pulsatile, hepatic artery). Control livers were preserved using the clinical golden standard: static cold storage. In the HMP group, pressure, flow and temperature were continuously monitored for 24 h. At time-points t = 0, 2, 4, 8, 12, and 24 h samples of University of Wisconsin machine preservation solution were taken for measurement of partial oxygen pressure (pO(2)) and lacto-dehydrogenase. Biopsies in every lobe were taken for histology and electron microscopy; samples of ice, preservation solution, liver surface, and bile were taken and cultured to determine sterility. Results showed that temperature was maintained at 0-4 degrees C; perfusion pressure was maintained at 4 mmHg and 30/20 mmHg for portal vein and hepatic artery, respectively. Flow was approximately 350 and 80 ml/min, respectively, but decreased in the portal vein, probably due to edema formation. Arterial pO(2) was kept at 100 kPa. Histology showed complete perfusion of the liver with no major damage to hepatocytes, bile ducts, and non-parenchymal cells compared to control livers. The machine perfusion system complied to the design criteria and will have to demonstrate the superiority of machine perfusion over cold storage in transplant experiments.

  5. Microfluidic resonant waveguide grating biosensor system for whole cell sensing

    NASA Astrophysics Data System (ADS)

    Zaytseva, Natalya; Miller, William; Goral, Vasily; Hepburn, Jerry; Fang, Ye

    2011-04-01

    We report on a fluidic resonant waveguide grating (RWG) biosensor system that enables medium throughput measurements of cellular responses under microfluidics in a 32-well format. Dynamic mass redistribution assays under microfluidics differentiate the cross-desensitization process between the β2-adrenoceptor agonist epinephrine and the adenylate cyclase activator forskolin mediated signaling. This system opens new possibility to study cellular processes that are otherwise difficult to achieve using conventional RWG configurations.

  6. Tailoring microfluidic systems for organ-like cell culture applications using multiphysics simulations

    NASA Astrophysics Data System (ADS)

    Hagmeyer, Britta; Schütte, Julia; Böttger, Jan; Gebhardt, Rolf; Stelzle, Martin

    2013-03-01

    Replacing animal testing with in vitro cocultures of human cells is a long-term goal in pre-clinical drug tests used to gain reliable insight into drug-induced cell toxicity. However, current state-of-the-art 2D or 3D cell cultures aiming at mimicking human organs in vitro still lack organ-like morphology and perfusion and thus organ-like functions. To this end, microfluidic systems enable construction of cell culture devices which can be designed to more closely resemble the smallest functional unit of organs. Multiphysics simulations represent a powerful tool to study the various relevant physical phenomena and their impact on functionality inside microfluidic structures. This is particularly useful as it allows for assessment of system functions already during the design stage prior to actual chip fabrication. In the HepaChip®, dielectrophoretic forces are used to assemble human hepatocytes and human endothelial cells in liver sinusoid-like structures. Numerical simulations of flow distribution, shear stress, electrical fields and heat dissipation inside the cell assembly chambers as well as surface wetting and surface tension effects during filling of the microchannel network supported the design of this human-liver-on-chip microfluidic system for cell culture applications. Based on the device design resulting thereof, a prototype chip was injection-moulded in COP (cyclic olefin polymer). Functional hepatocyte and endothelial cell cocultures were established inside the HepaChip® showing excellent metabolic and secretory performance.

  7. Nifedipine and thallium-201 myocardial perfusion in progressive systemic sclerosis

    SciTech Connect

    Kahan, A.; Devaux, J.Y.; Amor, B.; Menkes, C.J.; Weber, S.; Nitenberg, A.; Venot, A.; Guerin, F.; Degeorges, M.; Roucayrol, J.C.

    1986-05-29

    Heart disease in patients with progressive systemic sclerosis may be due in part to myocardial ischemia caused by a disturbance of the coronary microcirculation. To determine whether abnormalities of myocardial perfusion in this disorder are potentially reversible, we evaluated the effect of the coronary vasodilator nifedipine on myocardial perfusion assessed by thallium-201 scanning in 20 patients. Thallium-201 single-photon-emission computerized tomography was performed under control conditions and 90 minutes after 20 mg of oral nifedipine. The mean (+/- SD) number of left ventricular segments with perfusion defects decreased from 5.3 +/- 2.0 to 3.3 +/- 2.2 after nifedipine (P = 0.0003). Perfusion abnormalities were quantified by a perfusion score (0 to 2.0) assigned to each left ventricular segment and by a global perfusion score (0 to 18) for the entire left ventricle. The mean perfusion score in segments with resting defects increased from 0.97 +/- 0.24 to 1.26 +/- 0.44 after nifedipine (P less than 0.00001). The mean global perfusion score increased from 11.2 +/- 1.7 to 12.8 +/- 2.4 after nifedipine (P = 0.003). The global perfusion score increased by at least 2.0 in 10 patients and decreased by at least 2.0 in only 1. These observations reveal short-term improvement in thallium-201 myocardial perfusion with nifedipine in patients with progressive systemic sclerosis. The results are consistent with a potentially reversible abnormality of coronary vasomotion in this disorder, but the long-term therapeutic effects of nifedipine remain to be determined.

  8. An electrochemical albumin-sensing system utilizing microfluidic technology

    NASA Astrophysics Data System (ADS)

    Huang, Chao-June; Lu, Chiu-Chun; Lin, Thong-Yueh; Chou, Tse-Chuan; Lee, Gwo-Bin

    2007-04-01

    This paper reports an integrated microfluidic chip capable of detecting the concentration of albumin in urine by using an electrochemical method in an automatic format. The integrated microfluidic chip was fabricated by using microelectromechanical system techniques. The albumin detection was conducted by using the electrochemical sensing method, in which the albumin in urine was detected by measuring the difference of peak currents between a bare reference electrode and an albumin-adsorption electrode. To perform the detection of the albumin in an automatic format, pneumatic microvalves and micropumps were integrated onto the microfluidic chip. The albumin sample and interference mixture solutions such as homovanillic acid, dopamine, norepinephrine and epinephrine were first stored in one of the three reservoirs. Then the solution comprising the albumin sample and interference solutions was transported to pass through the detection zone utilizing the pneumatic micropump. Experimental data showed that the developed system can successfully detect the concentration of the albumin in the existence of interference materials. When compared with the traditional albumin-sensing method, smaller amounts of samples were required to perform faster detection by using the integrated microfluidic chip. Additionally, the microfluidic chip integrated with pneumatic micropumps and microvalves facilitates the transportation of the samples in an automatic mode with lesser human intervention. The development of the integrated microfluidic albumin-sensing system may be promising for biomedical applications. Preliminary results of the current paper were presented at the 2nd International Meeting on Microsensors and Microsystems 2006 (National Cheng Kung University, Tainan, Taiwan, 15-18 January).

  9. 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.

  10. Acoustothermal heating of polydimethylsiloxane microfluidic system

    NASA Astrophysics Data System (ADS)

    Ha, Byung Hang; Lee, Kang Soo; Destgeer, Ghulam; Park, Jinsoo; Choung, Jin Seung; Jung, Jin Ho; Shin, Jennifer Hyunjong; Sung, Hyung Jin

    2015-07-01

    We report an observation of rapid (exceeding 2,000 K/s) heating of polydimethylsiloxane (PDMS), one of the most popular microchannel materials, under cyclic loadings at high (~MHz) frequencies. A microheater was developed based on the finding. The heating mechanism utilized vibration damping in PDMS induced by sound waves that were generated and precisely controlled using a conventional surface acoustic wave (SAW) microfluidic system. The refraction of SAW into the PDMS microchip, called the leaky SAW, takes a form of bulk wave and rapidly heats the microchannels in a volumetric manner. The penetration depths were measured to range from 210 μm to 1290 μm, enough to cover most sizes of microchannels. The energy conversion efficiency was SAW frequency-dependent and measured to be the highest at around 30 MHz. Independent actuation of each interdigital transducer (IDT) enabled independent manipulation of SAWs, permitting spatiotemporal control of temperature on the microchip. All the advantages of this microheater facilitated a two-step continuous flow polymerase chain reaction (CFPCR) to achieve the billion-fold amplification of a 134 bp DNA amplicon in less than 3 min.

  11. 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.

  12. Perfusion Electronic Record Documentation Using Epic Systems Software.

    PubMed

    Steffens, Thomas G; Gunser, John M; Saviello, George M

    2015-12-01

    This paper describes the design and use of Epic Systems software for documentation of perfusion activities as part of the patient electronic medical record. The University of Wisconsin Hospital and Clinics adapted the Anesthesia software module and developed an integrated perfusion/anesthesia record for the documentation of cardiac and non-cardiac surgical procedures. This project involved multiple committees, approvals, and training to successfully implement. This article will describe our documentation options, concepts, design, challenges, training, and implementation during our initial experience.

  13. Optical two-beam traps in microfluidic systems

    NASA Astrophysics Data System (ADS)

    Berg-Sørensen, Kirstine

    2016-08-01

    An attractive solution for optical trapping and stretching by means of two counterpropagating laser beams is to embed waveguides or optical fibers in a microfluidic system. The microfluidic system can be constructed in different materials, ranging from soft polymers that may easily be cast in a rapid prototyping manner, to hard polymers that could even be produced by injection moulding, or to silica in which waveguides may either be written directly, or with grooves for optical fibers. Here, we review different solutions to the system and also show results obtained in a polymer chip with DUV written waveguides and in an injection molded polymer chip with grooves for optical fibers.

  14. Production of nanoparticle drug delivery systems with microfluidics tools.

    PubMed

    Khan, Ikram Ullah; Serra, Christophe A; Anton, Nicolas; Vandamme, Thierry F

    2015-04-01

    Nowadays the development of composite nano- and microparticles is an extensively studied area of research. This interest is growing because of the potential use of such particles in drug delivery systems. Indeed they can be used in various medical disciplines depending upon their sizes and their size distribution, which determine their final biomedical applications. Amongst the different techniques to produce nanoparticles, microfluidic techniques allow preparing particles having a specific size, a narrow size distribution and high encapsulation efficiency with ease. This review covers the general description of microfluidics, its techniques, advantages and disadvantages with focus on the encapsulation of active principles in polymeric nanoparticles as well as on pure drug nanoparticles. Polymeric nanoparticles constitute the majority of the examples reported; however lipid nanoparticulate systems (DNA, SiRNA nanocarriers) are very comparable and their formulation processes are in most cases exactly similar. Accordingly this review focuses also on active ingredient nanoparticles formulated by nanoprecipitation processes in microfluidic devices in general. It also provides detailed description of the different geometries of most common microfluidic devices and the crucial parameters involved in techniques designed to obtain the desired properties. Although the classical fabrication of nanoparticles drug delivery systems in batch is extremely well-described and developed, their production with microfluidic tools arises today as an emerging field with much more potential. In this review we present and discuss these new possibilities for biomedical applications through the current emerging developments.

  15. Microfluidics-based integrated airborne pathogen detection systems

    NASA Astrophysics Data System (ADS)

    Northrup, M. Allen; Alleman-Sposito, Jennifer; Austin, Todd; Devitt, Amy; Fong, Donna; Lin, Phil; Nakao, Brian; Pourahmadi, Farzad; Vinas, Mary; Yuan, Bob

    2006-09-01

    Microfluidic Systems is focused on building microfluidic platforms that interface front-end mesofluidics to handle real world sample volumes for optimal sensitivity coupled to microfluidic circuitry to process small liquid volumes for complex reagent metering, mixing, and biochemical analysis, particularly for pathogens. MFSI is the prime contractor on two programs for the US Department of Homeland Security: BAND (Bioagent Autonomous Networked Detector) and IBADS (Instantaneous Bio-Aerosol Detection System). The goal of BAND is to develop an autonomous system for monitoring the air for known biological agents. This consists of air collection, sample lysis, sample purification, detection of DNA, RNA, and toxins, and a networked interface to report the results. For IBADS, MFSI is developing the confirmatory device which must verify the presence of a pathogen with 5 minutes of an air collector/trigger sounding an alarm. Instrument designs and biological assay results from both BAND and IBADS will be presented.

  16. Fabrication of microfluidic systems in poly(dimethylsiloxane).

    PubMed

    McDonald, J C; Duffy, D C; Anderson, J R; Chiu, D T; Wu, H; Schueller, O J; Whitesides, G M

    2000-01-01

    Microfluidic devices are finding increasing application as analytical systems, biomedical devices, tools for chemistry and biochemistry, and systems for fundamental research. Conventional methods of fabricating microfluidic devices have centered on etching in glass and silicon. Fabrication of microfluidic devices in poly(dimethylsiloxane) (PDMS) by soft lithography provides faster, less expensive routes than these conventional methods to devices that handle aqueous solutions. These soft-lithographic methods are based on rapid prototyping and replica molding and are more accessible to chemists and biologists working under benchtop conditions than are the microelectronics-derived methods because, in soft lithography, devices do not need to be fabricated in a cleanroom. This paper describes devices fabricated in PDMS for separations, patterning of biological and nonbiological material, and components for integrated systems.

  17. Continuously perfused, non-cross-contaminating microfluidic chamber array for studying cellular responses to orthogonal combinations of matrix and soluble signals.

    PubMed

    Park, Edward S; Brown, Ashley C; DiFeo, Michael A; Barker, Thomas H; Lu, Hang

    2010-03-07

    We present a microfluidic cell culture array with unique versatility and parallelization for experimental trials requiring perfusion cultures. Specifically, we realize a rectangular chamber array in a PDMS device with three attributes: (i) continuous perfusion; (ii) flow paths that forbid cross-chamber contamination; and (iii) chamber shielding from direct perfusion to minimize shear-induced cell behaviour. These attributes are made possible by a bridge-and-underpass architecture, where flow streams travel vertically to pass over (or under) channels and on-chip valves. The array is also designed for considerable versatility, providing subarray, row, column, or single chamber addressing. It allows for incubation with adsorbed molecules, perfusion of differing media, seeding or extraction of cells, and assay staining. We use the device to characterize different phenotypes of alveolar epithelial type II (ATII) cells, particularly the extent of epithelial-to-mesenchymal transition (EMT), a highly suspected pathway in tissue regeneration and fibrosis. Cells are cultured on combinations of matrix proteins (fibronectin or laminin by row) and soluble signals (with or without transforming growth factor-beta1 by column) with two repeats per chip. Fluorescent assays are performed in the array to assess viability, cytoskeletal organization, and cell-cell junction formation. Assay and morphological data are used to tease-out effects of cues driving each phenotype, confirming this as an effective and versatile combinatorial screening platform.

  18. Fully integrated microfluidic separations systems for biochemical analysis.

    PubMed

    Roman, Gregory T; Kennedy, Robert T

    2007-10-19

    Over the past decade a tremendous amount of research has been performed using microfluidic analytical devices to detect over 200 different chemical species. Most of this work has involved substantial integration of fluid manipulation components such as separation channels, valves, and filters. This level of integration has enabled complex sample processing on miniscule sample volumes. Such devices have also demonstrated high throughput, sensitivity, and separation performance. Although the miniaturization of fluidics has been highly valuable, these devices typically rely on conventional ancillary equipment such as power supplies, detection systems, and pumps for operation. This auxiliary equipment prevents the full realization of a "lab-on-a-chip" device with complete portability, autonomous operation, and low cost. Integration and/or miniaturization of ancillary components would dramatically increase the capability and impact of microfluidic separations systems. This review describes recent efforts to incorporate auxiliary equipment either as miniaturized plug-in modules or directly fabricated into the microfluidic device.

  19. Microfluidic systems for electrochemical and biological studies

    SciTech Connect

    Ackler, H., LLNL

    1998-05-01

    Microfluidic devices with microelectrodes have the potential to enable studies of phenomena at size scales where behavior may be dominated by different mechanisms than at macroscales. Through our work developing microfluidic devices for dielectrophoretic separation and sensing of cells and particles, we have fabricated devices from which general or more specialized research devices may be derived. Fluid channels from 80 {micro}m wide X 20 {micro}m deep to 1 mm wide to 200 {micro}m deep have been fabricated in glass, with lithographically patterned electrodes from 10 to 80 {micro}m wide on one or both sides on the channels and over topographies tens of microns in heights. the devices are designed to easily interface to electronic and fluidic interconnect packages that permit reuse of devices, rather than one-time use, crude glue-based methods. Such devices may be useful for many applications of interest to the electrochemical and biological community.

  20. A metering rotary nanopump for microfluidic systems

    PubMed Central

    Darby, Scott G.; Moore, Matthew R.; Friedlander, Troy A.; Schaffer, David K.; Reiserer, Ron S.; Wikswo, John P.

    2014-01-01

    We describe the design, fabrication, and testing of a microfabricated metering rotary nanopump for the purpose of driving fluid flow in microfluidic devices. The miniature peristaltic pump is composed of a set of microfluidic channels wrapped in a helix around a central cam shaft in which a non-cylindrical cam rotates. The cam compresses the helical channels to induce peristaltic flow as it is rotated. The polydimethylsiloxane (PDMS) nanopump design is able to produce intermittent delivery or removal of several nanoliters of fluid per revolution as well as consistent continuous flow rates ranging from as low as 15 nL/min to above 1.0 µL/min. At back pressures encountered in typical microfluidic devices, the pump acts as a high impedance flow source. The durability, biocompatibility, ease of integration with soft-lithographic fabrication, the use of a simple rotary motor instead of multiple synchronized pneumatic or mechanical actuators, and the absence of power consumption or fluidic conductance in the resting state all contribute to a compact pump with a low cost of fabrication and versatile implementation. This suggests that the pump design may be useful for a wide variety of biological experiments and point of care devices. PMID:20959938

  1. A metering rotary nanopump for microfluidic systems.

    PubMed

    Darby, Scott G; Moore, Matthew R; Friedlander, Troy A; Schaffer, David K; Reiserer, Ron S; Wikswo, John P; Seale, Kevin T

    2010-12-07

    We describe the design, fabrication, and testing of a microfabricated metering rotary nanopump for the purpose of driving fluid flow in microfluidic devices. The miniature peristaltic pump is composed of a set of microfluidic channels wrapped in a helix around a central camshaft in which a non-cylindrical cam rotates. The cam compresses the helical channels to induce peristaltic flow as it is rotated. The polydimethylsiloxane (PDMS) nanopump design is able to produce intermittent delivery or removal of several nanolitres of fluid per revolution as well as consistent continuous flow rates ranging from as low as 15 nL min(-1) to above 1.0 µL min(-1). At back pressures encountered in typical microfluidic devices, the pump acts as a high impedance flow source. The durability, biocompatibility, ease of integration with soft-lithographic fabrication, the use of a simple rotary motor instead of multiple synchronized pneumatic or mechanical actuators, and the absence of power consumption or fluidic conductance in the resting state all contribute to a compact pump with a low cost of fabrication and versatile implementation. This suggests that the pump design may be useful for a wide variety of biological experiments and point of care devices.

  2. A smartphone controlled handheld microfluidic liquid handling system.

    PubMed

    Li, Baichen; Li, Lin; Guan, Allan; Dong, Quan; Ruan, Kangcheng; Hu, Ronggui; Li, Zhenyu

    2014-10-21

    Microfluidics and lab-on-a-chip technologies have made it possible to manipulate small volume liquids with unprecedented resolution, automation and integration. However, most current microfluidic systems still rely on bulky off-chip infrastructures such as compressed pressure sources, syringe pumps and computers to achieve complex liquid manipulation functions. Here, we present a handheld automated microfluidic liquid handling system controlled by a smartphone, which is enabled by combining elastomeric on-chip valves and a compact pneumatic system. As a demonstration, we show that the system can automatically perform all the liquid handling steps of a bead-based HIV1 p24 sandwich immunoassay on a multi-layer PDMS chip without any human intervention. The footprint of the system is 6 × 10.5 × 16.5 cm, and the total weight is 829 g including battery. Powered by a 12.8 V 1500 mAh Li battery, the system consumed 2.2 W on average during the immunoassay and lasted for 8.7 h. This handheld microfluidic liquid handling platform is generally applicable to many biochemical and cell-based assays requiring complex liquid manipulation and sample preparation steps such as FISH, PCR, flow cytometry and nucleic acid sequencing. In particular, the integration of this technology with read-out biosensors may help enable the realization of the long-sought Tricorder-like handheld in vitro diagnostic (IVD) systems.

  3. A Microfluidics-HPLC/Differential Mobility Spectrometer Macromolecular Detection System for Human and Robotic Missions

    NASA Technical Reports Server (NTRS)

    Coy, S. L.; Killeen, K.; Han, J.; Eiceman, G. A.; Kanik, I.; Kidd, R. D.

    2011-01-01

    Our goal is to develop a unique, miniaturized, solute analyzer based on microfluidics technology. The analyzer consists of an integrated microfluidics High Performance Liquid Chromatographic chip / Differential Mobility Spectrometer (?HPLCchip/ DMS) detection system

  4. A Microfluidics-HPLC/Differential Mobility Spectrometer Macromolecular Detection System for Human and Robotic Missions

    NASA Astrophysics Data System (ADS)

    Coy, S. L.; Killeen, K.; Han, J.; Eiceman, G. A.; Kanik, I.; Kidd, R. D.

    2011-03-01

    Our goal is to develop a unique, miniaturized, solute analyzer based on microfluidics technology. The analyzer consists of an integrated microfluidics High Performance Liquid Chromatographic chip/Differential Mobility Spectrometer (HPLC-chip/DMS) detection system.

  5. A Microfluidics-HPLC/Differential Mobility Spectrometer Macromolecular Detection System for Human and Robotic Missions

    NASA Technical Reports Server (NTRS)

    Coy, S. L.; Killeen, K.; Han, J.; Eiceman, G. A.; Kanik, I.; Kidd, R. D.

    2011-01-01

    Our goal is to develop a unique, miniaturized, solute analyzer based on microfluidics technology. The analyzer consists of an integrated microfluidics High Performance Liquid Chromatographic chip / Differential Mobility Spectrometer (?HPLCchip/ DMS) detection system

  6. Integrated microfluidic systems for high-performance genetic analysis.

    PubMed

    Liu, Peng; Mathies, Richard A

    2009-10-01

    Driven by the ambitious goals of genome-related research, fully integrated microfluidic systems have developed rapidly to advance biomolecular and, in particular, genetic analysis. To produce a microsystem with high performance, several key elements must be strategically chosen, including device materials, temperature control, microfluidic control, and sample/product transport integration. We review several significant examples of microfluidic integration in DNA sequencing, gene expression analysis, pathogen detection, and forensic short tandem repeat typing. The advantages of high speed, increased sensitivity, and enhanced reliability enable these integrated microsystems to address bioanalytical challenges such as single-copy DNA sequencing, single-cell gene expression analysis, pathogen detection, and forensic identification of humans in formats that enable large-scale and point-of-analysis applications.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. Nanostructured microfluidic digestion system for rapid high-performance proteolysis.

    PubMed

    Cheng, Gong; Hao, Si-Jie; Yu, Xu; Zheng, Si-Yang

    2015-02-07

    A novel microfluidic protein digestion system with a nanostructured and bioactive inner surface was constructed by an easy biomimetic self-assembly strategy for rapid and effective proteolysis in 2 minutes, which is faster than the conventional overnight digestion methods. It is expected that this work would contribute to rapid online digestion in future high-throughput proteomics.

  12. Microfluidic Radiometal Labeling Systems for Biomolecules

    SciTech Connect

    Reichert, D E; Kenis, P J. A.

    2011-12-29

    In a typical labeling procedure with radiometals, such as Cu-64 and Ga-68; a very large (~ 100-fold) excess of the non-radioactive reactant (precursor) is used to promote rapid and efficient incorporation of the radioisotope into the PET imaging agent. In order to achieve high specific activities, careful control of reaction conditions and extensive chromatographic purifications are required in order to separate the labeled compounds from the cold precursors. Here we propose a microfluidic approach to overcome these problems, and achieve high specific activities in a more convenient, semi-automated fashion and faster time frame. Microfluidic reactors, consisting of a network of micron-sized channels (typical dimensions in the range 10 - 300¼m), filters, separation columns, electrodes and reaction loops/chambers etched onto a solid substrate, are now emerging as an extremely useful technology for the intensification and miniaturization of chemical processes. The ability to manipulate, process and analyze reagent concentrations and reaction interfaces in both space and time within the channel network of a microreactor provides the fine level of reaction control that is desirable in PET radiochemistry practice. These factors can bring radiometal labeling, specifically the preparation of radio-labeled biomolecules such as antibodies, much closer to their theoretical maximum specific activities.

  13. 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

  14. 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.

  15. A novel extracorporeal kidney perfusion system: a concept model.

    PubMed

    Szajer, Michael; Shah, Gaurang; Kittur, Dilip; Searles, Bruce; Li, Lu; Bruch, David; Darling, Edward

    2004-01-01

    The number of patients awaiting kidney transplantation has more than doubled in the past decade while the number of available donor organs has seen only a modest increase, leading to a critical shortage of organs. In response to this extreme shortage, the criteria for accepting organs have been modified to include marginal donors such as non-heart beating donors (NHBD). In these kidneys, determining viability is important for success of transplantation. Therefore, a study was undertaken to develop a system that would allow the extracorporeal assessment of function and compatibility of the donor organ before the patient is exposed to the risks associated with surgery. Following bilateral nephrectomy, the kidneys of 10 pigs (approximately 30 kg) were connected to a commercially available hypothermic pulsatile kidney perfusion apparatus. This system was modified to allow for normothermic pulsatile renal perfusion using the potential recipient's blood, via vascular access. These kidneys were perfused with the animal's blood for a minimum of two hours while various parameters were monitored. Perfusion pressures were kept between 60 and 90 mmHg, which correlated to flows between 70 and 150 mL/min. A decrease in perfusion pressure with a concomitant rise in flow over the two-hour period served as a good predictor of a viable and compatible graft. The modified kidney preservation system allows the normothermic, pulsatile extracorporeal perfusion of donor kidneys with the ability to monitor resistance to flow and urine production. This model also allows observation of the kidney for signs of hyperacute rejection. Further research needs to be conducted in order to determine if the system represents a methodology to increase the pool of available donor organs.

  16. An effervescent reaction micropump for portable microfluidic systems.

    PubMed

    Good, Brian T; Bowman, Christopher N; Davis, Robert H

    2006-05-01

    A water-activated, effervescent reaction was used to transport fluid in a controllable manner on a portable microfluidic device. The reaction between sodium bicarbonate and an organic acid, tartaric acid and/or benzoic acid, was modeled to analyze methods of controlling the generation of carbon-dioxide gas for the purposes of pumping fluids. Integration and testing of the effervescent reaction pump in a microfluidic device was made possible by using elastomeric polymers as both photopolymerizable septa and removable lids. These materials combined to enable facile access to otherwise gas-tight devices. Based on theoretical predictions for 0.33 mg of sodium bicarbonate and a stoichiometric amount of organic acid, the pumping flow rate could be varied from 0.01 microL s(-1) to 70 microL s(-1). The flow rate is controlled by adjusting any or all of the particle size of the least soluble reactant, the amount of reactants used, and the type of organic acid selected. The tartaric acid systems rapidly produce carbon dioxide; however, the gas generation rates dramatically decrease over the course of the reaction. In contrast, carbon dioxide production rate in the benzoic acid systems is lower and nearly constant for several minutes. Water activation and direct placement on a microfluidic device are key features of this micropump, which is therefore useful for portable microfluidic applications.

  17. Microfluidic Systems with Ion-Selective Membranes

    NASA Astrophysics Data System (ADS)

    Slouka, Zdenek; Senapati, Satyajyoti; Chang, Hsueh-Chia

    2014-06-01

    When integrated into microfluidic chips, ion-selective nanoporous polymer and solid-state membranes can be used for on-chip pumping, pH actuation, analyte concentration, molecular separation, reactive mixing, and molecular sensing. They offer numerous functionalities and are hence superior to paper-based devices for point-of-care biochips, with only slightly more investment in fabrication and material costs required. In this review, we first discuss the fundamentals of several nonequilibrium ion current phenomena associated with ion-selective membranes, many of them revealed by studies with fabricated single nanochannels/nanopores. We then focus on how the plethora of phenomena has been applied for transport, separation, concentration, and detection of biomolecules on biochips.

  18. Integrated microfluidic system with simultaneous emulsion generation and concentration.

    PubMed

    Koppula, Karuna S; Fan, Rong; Veerapalli, Kartik R; Wan, Jiandi

    2016-03-15

    Because the size, size distribution, and concentration of emulsions play an important role in most of the applications, controlled emulsion generation and effective concentration are of great interest in fundamental and applied studies. While microfluidics has been demonstrated to be able to produce emulsion drops with controlled size, size distribution, and hierarchical structures, progress of controlled generation of concentrated emulsions is limited. Here, we present an effective microfluidic emulsion generation system integrated with an orifice structure to separate aqueous droplets from the continuous oil phase, resulting in concentrated emulsion drops in situ. Both experimental and simulation results show that the efficiency of separation is determined by a balance between pressure drop and droplet accumulation near the orifice. By manipulating this balance via changing flow rates and microfluidic geometry, we can achieve monodisperse droplets on chip that have a concentration as high as 80,000 drops per microliter (volume fraction of 66%). The present approach thus provides insights to the design of microfluidic device that can be used to concentrate emulsions (drops and bubbles), colloidal particles (drug delivery polymer particles), and biological particles (cells and bacteria) when volume fractions as high as 66% are necessary. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Artificial Lymphatic Drainage Systems for Vascularized Microfluidic Scaffolds

    PubMed Central

    Wong, Keith H. K.; Truslow, James G.; Khankhel, Aimal H.; Chan, Kelvin L. S.; Tien, Joe

    2012-01-01

    The formation of a stably perfused microvasculature continues to be a major challenge in tissue engineering. Previous work has suggested the importance of a sufficiently large transmural pressure in maintaining vascular stability and perfusion. Here we show that a system of empty channels that provides a drainage function analogous to that of lymphatic microvasculature in vivo can stabilize vascular adhesion and maintain perfusion rate in dense, hydraulically resistive fibrin scaffolds in vitro. In the absence of drainage, endothelial delamination increased as scaffold density increased from 6 mg/mL to 30 mg/mL and scaffold hydraulic conductivity decreased by a factor of twenty. Single drainage channels exerted only localized vascular stabilization, the extent of which depended on the distance between vessel and drainage as well as scaffold density. Computational modeling of these experiments yielded an estimate of 0.40–1.36 cm H2O for the minimum transmural pressure required for vascular stability. We further designed and constructed fibrin patches (0.8 by 0.9 cm2) that were perfused by a parallel array of vessels and drained by an orthogonal array of drainage channels; only with the drainage did the vessels display long-term stability and perfusion. This work underscores the importance of drainage in vascularization, especially when a dense, hydraulically resistive scaffold is used. PMID:23281125

  20. 21 CFR 876.5880 - Isolated kidney perfusion and transport system and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Isolated kidney perfusion and transport system and....5880 Isolated kidney perfusion and transport system and accessories. (a) Identification. An isolated kidney perfusion and transport system and accessories is a device that is used to support a donated or...

  1. 21 CFR 876.5880 - Isolated kidney perfusion and transport system and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Isolated kidney perfusion and transport system and....5880 Isolated kidney perfusion and transport system and accessories. (a) Identification. An isolated kidney perfusion and transport system and accessories is a device that is used to support a donated or...

  2. 21 CFR 876.5880 - Isolated kidney perfusion and transport system and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Isolated kidney perfusion and transport system and....5880 Isolated kidney perfusion and transport system and accessories. (a) Identification. An isolated kidney perfusion and transport system and accesssories is a device that is used to support a donated or...

  3. 21 CFR 876.5880 - Isolated kidney perfusion and transport system and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Isolated kidney perfusion and transport system and....5880 Isolated kidney perfusion and transport system and accessories. (a) Identification. An isolated kidney perfusion and transport system and accesssories is a device that is used to support a donated or...

  4. 21 CFR 876.5880 - Isolated kidney perfusion and transport system and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Isolated kidney perfusion and transport system and....5880 Isolated kidney perfusion and transport system and accessories. (a) Identification. An isolated kidney perfusion and transport system and accesssories is a device that is used to support a donated or...

  5. Imaging label-free biosensor with microfluidic system

    NASA Astrophysics Data System (ADS)

    Jahns, S.; Glorius, P.; Hansen, M.; Nazirizadeh, Y.; Gerken, M.

    2015-06-01

    We present a microfluidic system suitable for parallel label-free detection of several biomarkers utilizing a compact imaging measurement system. The microfluidic system contains a filter unit to separate the plasma from human blood and a functionalized, photonic crystal slab sensor chip. The nanostructure of the photonic crystal slab sensor chip is fabricated by nanoimprint lithography of a period grating surface into a photoresist and subsequent deposition of a TiO2 layer. Photonic crystal slabs are slab waveguides supporting quasi-guided modes coupling to far-field radiation, which are sensitive to refractive index changes due to biomarker binding on the functionalized surface. In our imaging read-out system the resulting resonance shift of the quasi-guided mode in the transmission spectrum is converted into an intensity change detectable with a simple camera. By continuously taking photographs of the sensor surface local intensity changes are observed revealing the binding kinetics of the biomarker to its specific target. Data from two distinct measurement fields are used for evaluation. For testing the sensor chip, 1 μM biotin as well as 1 μM recombinant human CD40 ligand were immobilized in spotsvia amin coupling to the sensor surface. Each binding experiment was performed with 250 nM streptavidin and 90 nM CD40 ligand antibody dissolved in phosphate buffered saline. In the next test series, a functionalized sensor chip was bonded onto a 15 mm x 15 mm opening of the 75 mm x 25 mm x 2 mm microfluidic system. We demonstrate the functionality of the microfluidic system for filtering human blood such that only blood plasma was transported to the sensor chip. The results of first binding experiments in buffer with this test chip will be presented.

  6. Centrifugal Microfluidic System for Nucleic Acid Amplification and Detection

    PubMed Central

    Miao, Baogang; Peng, Niancai; Li, Lei; Li, Zheng; Hu, Fei; Zhang, Zengming; Wang, Chaohui

    2015-01-01

    We report here the development of a rapid PCR microfluidic system comprising a double-shaft turntable and centrifugal-based disc that rapidly drives the PCR mixture between chambers set at different temperatures, and the bidirectional flow improved the space utilization of the disc. Three heating resistors and thermistors maintained uniform, specific temperatures for the denaturation, annealing, and extension steps of the PCR. Infrared imaging showed that there was little thermal interference between reaction chambers; the system enabled the cycle number and reaction time of each step to be independently adjusted. To validate the function and efficiency of the centrifugal microfluidic system, a 350-base pair target gene from the hepatitis B virus was amplified and quantitated by fluorescence detection. By optimizing the cycling parameters, the reaction time was reduced to 32 min as compared to 120 min for a commercial PCR machine. DNA samples with concentrations ranging from 10 to 106 copies/mL could be quantitatively analyzed using this system. This centrifugal-based microfluidic platform is a useful system and possesses industrialization potential that can be used for portable diagnostics. PMID:26556354

  7. Myocardial perfusion abnormalities in asymptomatic patients with systemic lupus erythematosus

    SciTech Connect

    Hosenpud, J.D.; Montanaro, A.; Hart, M.V.; Haines, J.E.; Specht, H.D.; Bennett, R.M.; Kloster, F.E.

    1984-08-01

    Accelerated coronary artery disease and myocardial infarction in young patients with systemic lupus erythematosus is well documented; however, the prevalence of coronary involvement is unknown. Accordingly, 26 patients with systemic lupus were selected irrespective of previous cardiac history to undergo exercise thallium-201 cardiac scintigraphy. Segmental perfusion abnormalities were present in 10 of the 26 studies (38.5 percent). Five patients had reversible defects suggesting ischemia, four patients had persistent defects consistent with scar, and one patient had both reversible and persistent defects in two areas. There was no correlation between positive thallium results and duration of disease, amount of corticosteroid treatment, major organ system involvement or age. Only a history of pericarditis appeared to be associated with positive thallium-201 results (p less than 0.05). It is concluded that segmental myocardial perfusion abnormalities are common in patients with systemic lupus erythematosus. Whether this reflects large-vessel coronary disease or small-vessel abnormalities remains to be determined.

  8. Microfluidic systems with embedded materials and structures and method thereof

    DOEpatents

    Morse, Jeffrey D.; Rose, Klint A; Maghribi, Mariam; Benett, William; Krulevitch, Peter; Hamilton, Julie; Graff, Robert T.; Jankowski, Alan

    2007-03-06

    Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.

  9. Silicon photonic sensors incorporated in a digital microfluidic system.

    PubMed

    Lerma Arce, Cristina; Witters, Daan; Puers, Robert; Lammertyn, Jeroen; Bienstman, Peter

    2012-12-01

    Label-free biosensing with silicon nanophotonic microring resonator sensors has proven to be an excellent sensing technique for achieving high-throughput and high sensitivity, comparing favorably with other labeled and label-free sensing techniques. However, as in any biosensing platform, silicon nanophotonic microring resonator sensors require a fluidic component which allows the continuous delivery of the sample to the sensor surface. This component is typically based on microchannels in polydimethylsiloxane or other materials, which add cost and complexity to the system. The use of microdroplets in a digital microfluidic system, instead of continuous flows, is one of the recent trends in the field, where microliter- to picoliter-sized droplets are generated, transported, mixed, and split, thereby creating miniaturized reaction chambers which can be controlled individually in time and space. This avoids cross talk between samples or reagents and allows fluid plugs to be manipulated on reconfigurable paths, which cannot be achieved using the more established and more complex technology of microfluidic channels where droplets are controlled in series. It has great potential for high-throughput liquid handling, while avoiding on-chip cross-contamination. We present the integration of two miniaturized technologies: label-free silicon nanophotonic microring resonator sensors and digital microfluidics, providing an alternative to the typical microfluidic system based on microchannels. The performance of this combined system is demonstrated by performing proof-of-principle measurements of glucose, sodium chloride, and ethanol concentrations. These results show that multiplexed real-time detection and analysis, great flexibility, and portability make the combination of these technologies an ideal platform for easy and fast use in any laboratory.

  10. Microfluidics co-culture systems for studying tooth innervation

    PubMed Central

    Pagella, Pierfrancesco; Neto, Estrela; Jiménez-Rojo, Lucia; Lamghari, Meriem; Mitsiadis, Thimios A.

    2014-01-01

    Innervation plays a key role in the development and homeostasis of organs and tissues of the orofacial complex. Among these structures, teeth are peculiar organs as they are not innervated until later stages of development. Furthermore, the implication of neurons in tooth initiation, morphogenesis and differentiation is still controversial. Co-cultures constitute a valuable method to investigate and manipulate the interactions of nerve fibers with their target organs in a controlled and isolated environment. Conventional co-cultures between neurons and their target tissues have already been performed, but these cultures do not offer optimal conditions that are closely mimicking the in vivo situation. Indeed, specific cell populations require different culture media in order to preserve their physiological properties. In this study we evaluate the usefulness of a microfluidics system for co-culturing mouse trigeminal ganglia and developing teeth. This device allows the application of specific media for the appropriate development of both neuronal and dental tissues. The results show that mouse trigeminal ganglia and teeth survive for long culture periods in this microfluidics system, and that teeth maintain the attractive or repulsive effect on trigeminal neurites that has been observed in vivo. Neurites are repealed when co-cultured with embryonic tooth germs, while postnatal teeth exert an attractive effect to trigeminal ganglia-derived neurons. In conclusion, microfluidics system devices provide a valuable tool for studying the behavior of neurons during the development of orofacial tissues and organs, faithfully imitating the in vivo situation. PMID:25202282

  11. 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.

  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. Suspended microfluidics

    PubMed Central

    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.

    2013-01-01

    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. PMID:23729815

  14. Evaluation of peristaltic micromixers for highly integrated microfluidic systems.

    PubMed

    Kim, Duckjong; Rho, Hoon Suk; Jambovane, Sachin; Shin, Soojeong; Hong, Jong Wook

    2016-03-01

    Microfluidic devices based on the multilayer soft lithography allow accurate manipulation of liquids, handling reagents at the sub-nanoliter level, and performing multiple reactions in parallel processors by adapting micromixers. Here, we have experimentally evaluated and compared several designs of micromixers and operating conditions to find design guidelines for the micromixers. We tested circular, triangular, and rectangular mixing loops and measured mixing performance according to the position and the width of the valves that drive nanoliters of fluids in the micrometer scale mixing loop. We found that the rectangular mixer is best for the applications of highly integrated microfluidic platforms in terms of the mixing performance and the space utilization. This study provides an improved understanding of the flow behaviors inside micromixers and design guidelines for micromixers that are critical to build higher order fluidic systems for the complicated parallel bio/chemical processes on a chip.

  15. Microfluidic hubs, systems, and methods for interface fluidic modules

    SciTech Connect

    Bartsch, Michael S; Claudnic, Mark R; Kim, Hanyoup; Patel, Kamlesh D; Renzi, Ronald F; Van De Vreugde, James L

    2015-01-27

    Embodiments of microfluidic hubs and systems are described that may be used to connect fluidic modules. A space between surfaces may be set by fixtures described herein. In some examples a fixture may set substrate-to-substrate spacing based on a distance between registration surfaces on which the respective substrates rest. Fluidic interfaces are described, including examples where fluid conduits (e.g. capillaries) extend into the fixture to the space between surfaces. Droplets of fluid may be introduced to and/or removed from microfluidic hubs described herein, and fluid actuators may be used to move droplets within the space between surfaces. Continuous flow modules may be integrated with the hubs in some examples.

  16. Integrated microfluidic system capable of size-specific droplet generation with size-dependent droplet separation.

    PubMed

    Lee, Sangmin; Hong, Seok Jun; Yoo, Hyung Jung; Ahn, Jae Hyun; Cho, Dong-il Dan

    2013-06-01

    Droplet-based microfluidics is receiving much attention in biomedical research area due to its advantage in uniform size droplet generation. Our previous results have reported that droplet size plays an important role in drug delivery actuated by flagellated bacteria. Recently, many research groups have been reported the size-dependent separation of emulsion droplets by a microfluidic system. In this paper, an integrated microfluidic system is proposed to produce and sort specificsized droplets sequentially. Operation of the system relies on two microfluidic transport processes: initial generation of droplets by hydrodynamic focusing and subsequent separation of droplets by a T-junction channel. The microfluidic system is fabricated by the SU-8 rapid prototyping method and poly-di-methyl-siloxane (PDMS) replica molding. A biodegradable polymer, poly-capro-lactone (PCL), is used for the droplet material. Using the proposed integrated microfluidic system, specific-sized droplets which can be delivered by flagellated bacteria are successfully generated and obtained.

  17. Microfluidic liquid chromatography system for proteomic applications and biomarker screening.

    PubMed

    Lazar, Iulia M; Trisiripisal, Phichet; Sarvaiya, Hetal A

    2006-08-01

    A microfluidic liquid chromatography (LC) system for proteomic investigations that integrates all the necessary components for stand-alone operation, i.e., pump, valve, separation column, and electrospray interface, is described in this paper. The overall size of the LC device is small enough to enable the integration of two fully functional separation systems on a 3 in. x 1 in. glass microchip. A multichannel architecture that uses electroosmotic pumping principles provides the necessary functionality for eluent propulsion and sample valving. The flow rates generated within these chips are fully consistent with the requirements of nano-LC platforms that are routinely used in proteomic applications. The microfluidic device was evaluated for the analysis of a protein digest obtained from the MCF7 breast cancer cell line. The cytosolic protein extract was processed according to a shotgun protocol, and after tryptic digestion and prefractionation using strong cation exchange chromatography (SCX), selected sample subfractions were analyzed with conventional and microfluidic LC platforms. Using similar experimental conditions, the performance of the microchip LC was comparable to that obtained with benchtop instrumentation, providing an overlap of 75% in proteins that were identified by more than two unique peptides. The microfluidic LC analysis of a protein-rich SCX fraction enabled the confident identification of 77 proteins by using conventional data filtering parameters, of 39 proteins with p < 0.001, and of 5 proteins that are known to be cancer-specific biomarkers, demonstrating thus the potential applicability of these chips for future high-throughput biomarker screening applications.

  18. Microfluidic device integration of electrostatic corral trapping systems

    NASA Astrophysics Data System (ADS)

    Amin-Patel, Alaknanda P.

    This thesis describes the development, characterization, and application of the microfluidics device integration of electrostatic corral trapping systems. Optical traps or "laser tweezers", which are capable of trapping microscopic dielectric particles through the production of steep electromagnetic field gradients, have been significant in the development of the field of biophysics and the manipulation of microscopic objects. This method of trapping unfortunately has a fundamental size limitation, making it incapable of trapping molecular-scale objects. We have developed a new tool for the trapping and manipulation of nanoscale objects including single molecules, the corral trap, which has distinct characteristics that set it apart from other trapping techniques. In order to increase the versatility of this new trapping tool, steps have been taken to integrate corral traps in a microfluidic cell. The production of such integrated devices based on optical lithography techniques will be presented in detail. Corral trapping in microfluidics device is expected to have important future applications in areas such as biomedical assays, ultra-sensitive biochemical analysis, and DNA manipulation and screening. Novelty: A novel method for the trapping of single molecules has been successfully used for the trapping of single ssDNA molecules.

  19. Label-free cell separation and sorting in microfluidic systems

    PubMed Central

    Gossett, Daniel R.; Weaver, Westbrook M.; Mach, Albert J.; Hur, Soojung Claire; Tse, Henry Tat Kwong; Lee, Wonhee; Amini, Hamed

    2010-01-01

    Cell separation and sorting are essential steps in cell biology research and in many diagnostic and therapeutic methods. Recently, there has been interest in methods which avoid the use of biochemical labels; numerous intrinsic biomarkers have been explored to identify cells including size, electrical polarizability, and hydrodynamic properties. This review highlights microfluidic techniques used for label-free discrimination and fractionation of cell populations. Microfluidic systems have been adopted to precisely handle single cells and interface with other tools for biochemical analysis. We analyzed many of these techniques, detailing their mode of separation, while concentrating on recent developments and evaluating their prospects for application. Furthermore, this was done from a perspective where inertial effects are considered important and general performance metrics were proposed which would ease comparison of reported technologies. Lastly, we assess the current state of these technologies and suggest directions which may make them more accessible. Figure A wide range of microfluidic technologies have been developed to separate and sort cells by taking advantage of differences in their intrinsic biophysical properties PMID:20419490

  20. Rapid laser prototyping of valves for microfluidic autonomous systems

    NASA Astrophysics Data System (ADS)

    Mohammed, M. I.; Abraham, E.; Y Desmulliez, M. P.

    2013-03-01

    Capillary forces in microfluidics provide a simple yet elegant means to direct liquids through flow channel networks. The ability to manipulate the flow in a truly automated manner has proven more problematic. The majority of valves require some form of flow control devices, which are manually, mechanically or electrically driven. Most demonstrated capillary systems have been manufactured by photolithography, which, despite its high precision and repeatability, can be labour intensive, requires a clean room environment and the use of fixed photomasks, limiting thereby the agility of the manufacturing process to readily examine alternative designs. In this paper, we describe a robust and rapid CO2 laser manufacturing process and demonstrate a range of capillary-driven microfluidic valve structures embedded within a microfluidic network. The manufacturing process described allows for advanced control and manipulation of fluids such that flow can be halted, triggered and delayed based on simple geometrical alterations to a given microchannel. The rapid prototyping methodology has been employed with PMMA substrates and a complete device has been created, ready for use, within 2-3 h. We believe that this agile manufacturing process can be applied to produce a range of complex autonomous fluidic platforms and allows subsequent designs to be rapidly explored.

  1. Microfluidic cell culture chip with multiplexed medium delivery and efficient cell/scaffold loading mechanisms for high-throughput perfusion 3-dimensional cell culture-based assays.

    PubMed

    Huang, Song-Bin; Wu, Min-Hsien; Wang, Shih-Siou; Lee, Gwo-Bin

    2011-06-01

    This study reports a microfluidic cell culture chip consisting of 48 microbioreactors for high-throughput perfusion 3-dimensional (3-D) cell culture-based assays. Its advantages include the capability for multiplexed and backflow-free medium delivery, and both efficient and high-throughput micro-scale, 3-D cell culture construct loading. In this work, the microfluidic cell culture chip is fabricated using two major processes, specifically, a computer-numerical-controlled (CNC) mold machining process and a polydimethylsiloxane (PDMS) replication process. The chip is composed of micropumps, microbioreactors, connecting microchannels and a cell/agarose scaffold loading mechanism. The performance of the new pneumatic micropumps and the cell/agarose scaffold loading mechanism has been experimentally evaluated. The experimental results show that this proposed multiplexed medium-pumping design is able to provide a uniform pumping rate ranging from 1.5 to 298.3 μl hr(-1) without any fluid backflow and the resultant medium contamination. In addition, the simple cell/agarose loading method has been proven to be able to load the 3-D cell culture construct uniformly and efficiently in all 48 microbioreactors investigated. Furthermore, a micro-scale, perfusion, 3-D cell culture-based assay has been successfully demonstrated using this proposed cell culture chip. The experimental results are also compared to a similar evaluation using a conventional static 3-D cell culture with a larger scale culture. It is concluded that the choice of a cell culture format can influence assay results. As a whole, because of the inherent advantages of a miniaturized perfusion 3-D cell culture assay, the cell culture chip not only can provide a stable, well-defined and more biologically-meaningful culture environment, but it also features a low consumption of research resources. Moreover, due to the integrated medium pumping mechanism and the simple cell/agarose loading method, this chip is

  2. Microfluidics and cancer analysis: cell separation, cell/tissue culture, cell mechanics, and integrated analysis systems.

    PubMed

    Pappas, Dimitri

    2016-01-21

    Among the growing number of tools available for cancer studies, microfluidic systems have emerged as a promising analytical tool to elucidate cancer cell and tumor function. Microfluidic methods to culture cells have created approaches to provide a range of environments from single-cell analysis to complex three-dimensional devices. In this review we discuss recent advances in tumor cell culture, cancer cell analysis, and advanced studies enabled by microfluidic systems.

  3. SmartBuild-a truly plug-n-play modular microfluidic system.

    PubMed

    Yuen, Po Ki

    2008-08-01

    In this Technical Note, for the first time, a truly "plug-n-play" modular microfluidic system (SmartBuild Plug-n-Play Modular Microfluidic System) is presented for designing and building integrated modular microfluidic systems for biological and chemical applications. The modular microfluidic system can be built by connecting multiple microfluidic components together to form a larger integrated system. The SmartBuild System comprises of a motherboard with interconnect channels/grooves, fitting components, microchannel inserts with different configurations and microchips/modules with different functionalities. Also, heaters, micropumps and valving systems can be designed and used in the system. Examples of an integrated mixing system and reaction systems are presented here to demonstrate the versatility of the SmartBuild System.

  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. Microfluidic mass production system for hydrogel microtubes for microbial culture

    NASA Astrophysics Data System (ADS)

    Fujimoto, Kazuma; Higashi, Kazuhiko; Onoe, Hiroaki; Miki, Norihisa

    2017-06-01

    In this study, we characterize the formation of hydrogel microtubes for microbial culture formed using a mass production system. We demonstrated microbial culture using hydrogel microtubes, which can protect the target microorganism inside from competitive microorganisms outside while they allow oxygen, nutrition, and byproducts to diffuse through. The hydrogel microtubes can be produced using a microfluidic device, but the scale-up of microtube production is crucial for practical applications. We propose and develop a fluidic system that can produce multiple microtubes in parallel. We experimentally characterized the microtube formation using the device and demonstrated microbial culture in the microtubes. Tube thickness was found to be a critical parameter for the culture.

  6. Applying microfluidics to electrophysiology.

    PubMed

    Eddington, David T

    2007-01-01

    Microfluidics can be integrated with standard electrophysiology techniques to allow new experimental modalities. Specifically, the motivation for the microfluidic brain slice device is discussed including how the device docks to standard perfusion chambers and the technique of passive pumping which is used to deliver boluses of neuromodulators to the brain slice. By simplifying the device design, we are able to achieve a practical solution to the current unmet electrophysiology need of applying multiple neuromodulators across multiple regions of the brain slice. This is achieved by substituting the standard coverglass substrate of the perfusion chamber with a thin microfluidic device bonded to the coverglass substrate. This was then attached to the perfusion chamber and small holes connect the open-well of the perfusion chamber to the microfluidic channels buried within the microfluidic substrate. These microfluidic channels are interfaced with ports drilled into the edge of the perfusion chamber to access and deliver stimulants. This project represents how the field of microfluidics is transitioning away from proof-of concept device demonstrations and into practical solutions for unmet experimental and clinical needs.

  7. Applying Microfluidics to Electrophysiology

    PubMed Central

    Eddington, David T.

    2007-01-01

    Microfluidics can be integrated with standard electrophysiology techniques to allow new experimental modalities. Specifically, the motivation for the microfluidic brain slice device is discussed including how the device docks to standard perfusion chambers and the technique of passive pumping which is used to deliver boluses of neuromodulators to the brain slice. By simplifying the device design, we are able to achieve a practical solution to the current unmet electrophysiology need of applying multiple neuromodulators across multiple regions of the brain slice. This is achieved by substituting the standard coverglass substrate of the perfusion chamber with a thin microfluidic device bonded to the coverglass substrate. This was then attached to the perfusion chamber and small holes connect the open-well of the perfusion chamber to the microfluidic channels buried within the microfluidic substrate. These microfluidic channels are interfaced with ports drilled into the edge of the perfusion chamber to access and deliver stimulants. This project represents how the field of microfluidics is transitioning away from proof-of concept device demonstrations and into practical solutions for unmet experimental and clinical needs. PMID:18989410

  8. 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.

  9. Temperature control system for water-perfused suits

    NASA Technical Reports Server (NTRS)

    Brengelmann, G. L.; Mckeag, M.; Rowell, L. B.

    1977-01-01

    A system used to control skin temperature in human subjects wearing water-perfused garments is described. It supplies 8 l/min at 10 psi with water temperature controlled within plus or minus 0.1 C. Temperature control is facilitated by a low circulating thermal mass and a fast responding heater based on a commercially available quartz heat lamp. The system is open so that hot or cold water can be added from the building mains to produce rates of change of water temperature exceeding 5 C/min. These capabilities allow semiautomatic control of skin temperature within plus or minus 0.1 C of desired wave forms.

  10. A microfluidic mixing system for single-molecule measurements.

    PubMed

    Pfeil, Shawn H; Wickersham, Charles E; Hoffmann, Armin; Lipman, Everett A

    2009-05-01

    This article describes the design and fabrication of a microfluidic mixing system optimized for ultrasensitive optical measurements. Channels are replica-molded in polydimethylsiloxane elastomer and sealed with fused-silica coverglass. The resulting devices have broad chemical compatibility and extremely low fluorescence background, enabling measurements of individual molecules under well-characterized nonequilibrium conditions. Fluid delivery and pressure connections are made using an interface that allows for rapid assembly, rapid sample exchange, and modular device replacement while providing access for high numerical aperture optics.

  11. Silicon micromachined pumps employing piezoelectric membrane actuation for microfluidic systems

    NASA Astrophysics Data System (ADS)

    Koch, Michael

    Microsystems technology is a rapidly expanding area that comprises electronics, mechanics and optics. In this field, physical/chemical sensing, fluid handling and optical communication are emerging as potential markets. Microfluidic systems like an implantable insulin pump, a drug delivery system and a total chemical analysis system are currently being developed by academia and industry around the world. This project contributes to the area of microfluidics in that a novel thick-film-on-silicon membrane actuator has been developed to allow inexpensive mass production of micropumps. To date piezoelectric plates have been surface mounted onto a silicon membrane. This single chip fabrication method can now be replaced by screen printing thick piezoelectric layers onto 4 inch silicon substrates. Two different pump types have been developed. These are membrane pumps with either cantilever valves or diffuser/nozzle valves. Pump rates between 100 and 200 μl min-1 and backpressures up to 4 kPa have been achieved with these pumps. Along with the technology of micropumps, simulators have been developed. A novel coupled FEM-CFD solver was realised by a computer controlled coupling of two commercially available packages (ANSYS and CFX-Flow3D). The results of this simulator were in good agreement with measurements on micromachined cantilever valves. CFX- Flow3D was also used to successfully model the behaviour of the diffuser/nozzle valve. Finally, the pump has been simulated using a continuity equation. A behavioural dynamic extension of the cantilever valve was necessary to achieve better prediction of the pump rates for higher frequencies. As well, a common process has been developed for microfluidic devices like micromixers, particle counters and sorters as well as flow sensors. The micromixer has been tested already and achieves mixing for input pressures between 2 and 7 kPa. This agrees with simulations of the diffusive mixing with CFX-Flow3D. Together with the micropump

  12. An easy-to-use microfluidic interconnection system to create quick and reversibly interfaced simple microfluidic devices

    NASA Astrophysics Data System (ADS)

    Pfreundt, Andrea; Brandt Andersen, Karsten; Dimaki, Maria; Svendsen, Winnie E.

    2015-11-01

    The presented microfluidic interconnection system provides an alternative for the individual interfacing of simple microfluidic devices fabricated in polymers such as polymethylmethacrylate, polycarbonate and cyclic olefin polymer. A modification of the device inlet enables the direct attachment of tubing (such as polytetrafluoroethylene tubing) secured and sealed by using a small plug, without the need for additional assembly, glue or o-rings. This provides a very clean connection that does not require additional, potentially incompatible, materials. The tightly sealed connection can withstand pressures above 250 psi and therefore supports applications with high flow rates or highly viscous fluids. The ease of incorporation, configuration, fabrication and use make this interconnection system ideal for the rapid prototyping of simple microfluidic devices or other integrated systems that require microfluidic interfaces. It provides a valuable addition to the toolbox of individual and small arrays of connectors suitable for micromachined or template-based injection molded devices since it does not require protruding, threaded or glued modifications on the inlet and avoids bulky and expensive fittings.

  13. Microfluidic systems and methods of transport and lysis of cells and analysis of cell lysate

    DOEpatents

    Culbertson, Christopher T.; Jacobson, Stephen C.; McClain, Maxine A.; Ramsey, J. Michael

    2004-08-31

    Microfluidic systems and methods are disclosed which are adapted to transport and lyse cellular components of a test sample for analysis. The disclosed microfluidic systems and methods, which employ an electric field to rupture the cell membrane, cause unusually rapid lysis, thereby minimizing continued cellular activity and resulting in greater accuracy of analysis of cell processes.

  14. Microfluidic systems and methods for transport and lysis of cells and analysis of cell lysate

    DOEpatents

    Culbertson, Christopher T [Oak Ridge, TN; Jacobson, Stephen C [Knoxville, TN; McClain, Maxine A [Knoxville, TN; Ramsey, J Michael [Knoxville, TN

    2008-09-02

    Microfluidic systems and methods are disclosed which are adapted to transport and lyse cellular components of a test sample for analysis. The disclosed microfluidic systems and methods, which employ an electric field to rupture the cell membrane, cause unusually rapid lysis, thereby minimizing continued cellular activity and resulting in greater accuracy of analysis of cell processes.

  15. Laminated plastic microfluidic components for biological and chemical systems

    SciTech Connect

    Martin, P.M.; Matson, D.W.; Bennett, W.D.; Lin, Y.; Hammerstrom, D.J.

    1999-07-01

    Laminated plastic microfluidic components are being developed for biological testing systems and chemical sensors. Applications include a DNA thermal cycler, DNA analytical systems, electrophoretic flow systems, dialysis systems, and metal sensors for ground water. This article describes fabrication processes developed for these plastic microfluidic components, and the fabrication of a chromium metal sensor and a microdialysis device. Most of the components have a stacked architecture. Using this architecture, the fluid flows, or is pumped through, as many as nine laminated functional levels. Functions include pumping, mixing, reaction, detection, reservoirs, separations, and electronics. Polyimide, poly(methylmethacrylate) (PMMA), and polycarbonate materials with thicknesses between 25 and 125 {mu}m are used to construct the components. This makes the components low cost, inert to many biological fluids and chemicals, and disposable. The components are fabricated by excimer laser micromachining the microchannel patterns and microstructures in the various laminates. In some cases, micropumps are integrated into these components to move the fluids. Vias and interconnects are also cut by the laser and integrated with micropumps. The laminates are sealed and bonded by adhesive and thermal processes and are leak tight. The parts withstand pressures as high as 790 kPa. Typical channel widths are 50 to 100 {mu}m, with aspect ratios near 5. {copyright} {ital 1999 American Vacuum Society.}

  16. 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).

  17. Label-free all-electronic biosensing in microfluidic systems

    NASA Astrophysics Data System (ADS)

    Stanton, Michael A.

    Label-free, all-electronic detection techniques offer great promise for advancements in medical and biological analysis. Electrical sensing can be used to measure both interfacial and bulk impedance changes in conducting solutions. Electronic sensors produced using standard microfabrication processes are easily integrated into microfluidic systems. Combined with the sensitivity of radiofrequency electrical measurements, this approach offers significant advantages over competing biological sensing methods. Scalable fabrication methods also provide a means of bypassing the prohibitive costs and infrastructure associated with current technologies. We describe the design, development and use of a radiofrequency reflectometer integrated into a microfluidic system towards the specific detection of biologically relevant materials. We developed a detection protocol based on impedimetric changes caused by the binding of antibody/antigen pairs to the sensing region. Here we report the surface chemistry that forms the necessary capture mechanism. Gold-thiol binding was utilized to create an ordered alkane monolayer on the sensor surface. Exposed functional groups target the N-terminus, affixing a protein to the monolayer. The general applicability of this method lends itself to a wide variety of proteins. To demonstrate specificity, commercially available mouse anti- Streptococcus Pneumoniae monoclonal antibody was used to target the full-length recombinant pneumococcal surface protein A, type 2 strain D39 expressed by Streptococcus Pneumoniae. We demonstrate the RF response of the sensor to both the presence of the surface decoration and bound SPn cells in a 1x phosphate buffered saline solution. The combined microfluidic sensor represents a powerful platform for the analysis and detection of cells and biomolecules.

  18. Microfluidic filtration system to isolate extracellular vesicles from blood.

    PubMed

    Davies, Ryan T; Kim, Junho; Jang, Su Chul; Choi, Eun-Jeong; Gho, Yong Song; Park, Jaesung

    2012-12-21

    Extracellular vesicles are released by various cell types, particularly tumor cells, and may be potential targets for blood-based cancer diagnosis. However, studies performed on blood-borne vesicles to date have been limited by lack of effective, standardized purification strategies. Using in situ prepared nanoporous membranes, we present a simple strategy employing a microfluidic filtration system to isolate vesicles from whole blood samples. This method can be applied to purify nano-sized particles from blood allowing isolation of intact extracellular vesicles, avoiding the need for laborious and potentially damaging centrifugation steps or overly specific antibody-based affinity purification. Porous polymer monoliths were integrated as membranes into poly(methyl methacrylate) microfluidic chips by benchtop UV photopolymerization through a mask, allowing precise positioning of membrane elements while preserving simplicity of device preparation. Pore size could be manipulated by changing the ratio of porogenic solvent to prepolymer solution, and was tuned to a size proper for extraction of vesicles. Using the membrane as a size exclusion filter, we separated vesicles from cells and large debris by injecting whole blood under pressure through the microfluidic device. To enhance isolation purity, DC electrophoresis was employed as an alternative driving force to propel particles across the filter and increase the separation efficiency of vesicles from proteins. From the whole blood of melanoma-grown mice, we isolated extracellular vesicles and performed RT-PCR to verify their contents of RNA. Melan A mRNA derived from melanoma tumor cells were found enriched in filtered samples, confirming the recovery of vesicles via their cargo. This filtration system can be incorporated into other on-chip processes enabling integrated sample preparation for the downstream analysis of blood-based extracellular vesicles.

  19. Development of Microfluidic Systems Enabling High-Throughput Single-Cell Protein Characterization

    PubMed Central

    Fan, Beiyuan; Li, Xiufeng; Chen, Deyong; Peng, Hongshang; Wang, Junbo; Chen, Jian

    2016-01-01

    This article reviews recent developments in microfluidic systems enabling high-throughput characterization of single-cell proteins. Four key perspectives of microfluidic platforms are included in this review: (1) microfluidic fluorescent flow cytometry; (2) droplet based microfluidic flow cytometry; (3) large-array micro wells (microengraving); and (4) large-array micro chambers (barcode microchips). We examine the advantages and limitations of each technique and discuss future research opportunities by focusing on three key performance parameters (absolute quantification, sensitivity, and throughput). PMID:26891303

  20. Microfluidics and photonics for Bio-System-on-a-Chip: A review of advancements in technology towards a microfluidic flow cytometry chip

    PubMed Central

    Godin, Jessica; Chen, Chun-Hao; Cho, Sung Hwan; Qiao, Wen; Tsai, Frank; Lo, Yu-Hwa

    2009-01-01

    Microfluidics and photonics come together to form a field commonly referred to as ‘optofluidics’. Flow cytometry provides the field with a technology base from which both microfluidic and photonic components be developed and integrated into a useful device. This article reviews some of the more recent developments to familiarize a reader with the current state of the technologies and also highlights the requirements of the device and how researchers are working to meet these needs. A microfluidic flow cytometer protoype employing on-chip lenses for illumination and light collection in conjunction with a microfluidic sample flow system for device miniaturization. PMID:19343660

  1. Microfluidic single-cell analysis for systems immunology.

    PubMed

    Junkin, Michael; Tay, Savaş

    2014-04-07

    The immune system constantly battles infection and tissue damage, but exaggerated immune responses lead to allergies, autoimmunity and cancer. Discrimination of self from foreign and the fine-tuning of immunity are achieved by information processing pathways, whose regulatory mechanisms are little understood. Cell-to-cell variability and stochastic molecular interactions result in diverse cellular responses to identical signaling inputs, casting doubt on the reliability of traditional population-averaged analyses. Furthermore, dynamic molecular and cellular interactions create emergent properties that change over multiple time scales. Understanding immunity in the face of complexity and noisy dynamics requires time-dependent analysis of single-cells in a proper context. Microfluidic systems create precisely defined microenvironments by controlling fluidic and surface chemistries, feature sizes, geometries and signal input timing, and thus enable quantitative multi-parameter analysis of single cells. Such qualities allow observable dynamic environments approaching in vivo levels of biological complexity. Seamless parallelization of functional units in microfluidic devices allows high-throughput measurements, an essential feature for statistically meaningful analysis of naturally variable biological systems. These abilities recapitulate diverse scenarios such as cell-cell signaling, migration, differentiation, antibody and cytokine production, clonal selection, and cell lysis, thereby enabling accurate and meaningful study of immune behaviors in vitro.

  2. Blood compatible microfluidic system for pharmacokinetic studies in small animals.

    PubMed

    Convert, Laurence; Baril, Frédérique Girard; Boisselle, Vincent; Pratte, Jean-François; Fontaine, Réjean; Lecomte, Roger; Charette, Paul G; Aimez, Vincent

    2012-11-21

    New radiotracer developments for nuclear medicine imaging require the analysis of blood as a function of time in small animal models. A microfluidic device was developed to monitor the radioactivity concentration in the blood of rats and mice in real time. The microfluidic technology enables a large capture solid angle and a reduction in the separation distance between the sample and detector, thus increasing the detection efficiency. This in turn allows a reduction of the required detection volume without compromising sensitivity, an important advantage with rodent models having a small total blood volume (a few ml). A robust fabrication process was developed to manufacture the microchannels on top of unpackaged p-i-n photodiodes without altering detector performance. The microchannels were fabricated with KMPR, an epoxy-based photoresist similar to SU-8 but with improved resistance to stress-induced fissuring. Surface passivation of the KMPR enables non-diluted whole blood to flow through the channel for up to 20 min at low speed without clotting. The microfluidic device was embedded in a portable blood counter with dedicated electronics, pumping unit and computer control software for utilisation next to a small animal nuclear imaging scanner. Experimental measurements confirmed model predictions and showed a 4- to 19-fold improvement in detection efficiency over existing catheter-based devices, enabling a commensurate reduction in sampled blood volume. A linear dose-response relationship was demonstrated for radioactivity concentrations typical of experiments with rodents. The system was successfully used to measure the blood input function of rats in real time after radiotracer injection.

  3. Passive injection control for microfluidic systems

    DOEpatents

    Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

    2004-12-21

    Apparatus for eliminating siphoning, "dead" regions, and fluid concentration gradients in microscale analytical devices. In its most basic embodiment, the present invention affords passive injection control for both electric field-driven and pressure-driven systems by providing additional fluid flow channels or auxiliary channels disposed on either side of a sample separation column. The auxiliary channels are sized such that volumetric fluid flow rate through these channels, while sufficient to move the sample away from the sample injection region in a timely fashion, is less than that through the sample separation channel or chromatograph.

  4. Design, modeling and characterization of microfluidic architectures for high flow rate, small footprint microfluidic systems.

    PubMed

    Saias, Laure; Autebert, Julien; Malaquin, Laurent; Viovy, Jean-Louis

    2011-03-07

    We propose a strategy for optimizing distribution of flow in a microfluidic chamber for microreactor, lateral flow assay and immunocapture applications. It is aimed at maximizing flow throughput, while keeping footprint, cell thickness, and shear stress in the distribution channels at a minimum, and offering a uniform flow field along the whole analysis chamber. In order to minimize footprint, the traditional tree-like or "rhombus" design, in which distribution microchannels undergo a series of splittings into two subchannels with equal lengths and widths, was replaced by a design in which subchannel lengths are unequal, and widths are analytically adapted within the Hele-Shaw approximation, in order to keep the flow resistance uniform along all flow paths. The design was validated by hydrodynamic flow simulation using COMSOL finite element software. Simulations show that, if the channel is too narrow, the Hele-Shaw approximation loses accuracy, and the flow velocity in the chamber can fluctuate by up to 20%. We thus used COMSOL simulation to fine-tune the channel parameters, and obtained a fluctuation of flow velocity across the whole chamber below 10%. The design was then implemented into a PDMS device, and flow profiles were measured experimentally using particle tracking. Finally, we show that this system can be applied to cell sorting in self-assembling magnetic arrays, increasing flow throughput by a factor 100 as compared to earlier reported designs.

  5. Microfluidic cell culture systems with integrated sensors for drug screening

    NASA Astrophysics Data System (ADS)

    Grist, Samantha; Yu, Linfen; Chrostowski, Lukas; Cheung, Karen C.

    2012-03-01

    Cell-based testing is a key step in drug screening for cancer treatments. A microfluidic platform can permit more precise control of the cell culture microenvironment, such as gradients in soluble factors. These small-scale devices also permit tracking of low cell numbers. As a new screening paradigm, a microscale system for integrated cell culture and drug screening promises to provide a simple, scalable tool to apply standardized protocols used in cellular response assays. With the ability to dynamically control the microenvironment, we can create temporally varying drug profiles to mimic physiologically measured profiles. In addition, low levels of oxygen in cancerous tumors have been linked with drug resistance and decreased likelihood of successful treatment and patient survival. Our work also integrates a thin-film oxygen sensor with a microfluidic oxygen gradient generator which will in future allow us to create spatial oxygen gradients and study effects of hypoxia on cell response to drug treatment. In future, this technology promises to improve cell-based validation in the drug discovery process, decreasing the cost and increasing the speed in screening large numbers of compounds.

  6. High-viscosity fluid threads in weakly diffusive microfluidic systems

    NASA Astrophysics Data System (ADS)

    Cubaud, T.; Mason, T. G.

    2009-07-01

    We provide an overview of the flow dynamics of highly viscous miscible liquids in microfluidic geometries. We focus on the lubricated transport of high-viscosity fluids interacting with less viscous fluids, and we review methods for producing and manipulating single and multiple core-annular flows, i.e. viscous threads, in compact and plane microgeometries. In diverging slit microchannels, a thread's buckling instabilities can be employed for generating ordered and disordered miscible microstructures, as well as for partially blending low- and high-viscosity materials. The shear-induced destabilization of a thread that flows off-center in a square microchannel is examined as a means for continuously producing miscible dispersions. We show original compound threads and viscous dendrites that are generated using three fluids, each of which has a large viscosity contrast with the others. Thread motions in zones of microchannel extensions are examined in both miscible and immiscible environments. We demonstrate that high-viscosity fluid threads in weakly diffusive microfluidic systems correspond to the viscous primary flow and can be used as a starting point for studying and understanding the destabilizing effects of interfacial tension as well as diffusion. Characteristic of lubricated transport, threads facilitate the transport of very viscous materials in small fluidic passages, while mitigating dissipation. Threads are also potentially promising for soft material synthesis and diagnostics with independent control of the thread specific surface and residence time in micro-flow reactors.

  7. Modular microfluidic system as a model of cystic fibrosis airways

    PubMed Central

    Skolimowski, M.; Weiss Nielsen, M.; Abeille, F.; Skafte-Pedersen, P.; Sabourin, D.; Fercher, A.; Papkovsky, D.; Molin, S.; Taboryski, R.; Sternberg, C.; Dufva, M.; Geschke, O.; Emnéus, J.

    2012-01-01

    A modular microfluidic airways model system that can simulate the changes in oxygen tension in different compartments of the cystic fibrosis (CF) airways was designed, developed, and tested. The fully reconfigurable system composed of modules with different functionalities: multichannel peristaltic pumps, bubble traps, gas exchange chip, and cell culture chambers. We have successfully applied this system for studying the antibiotic therapy of Pseudomonas aeruginosa, the bacteria mainly responsible for morbidity and mortality in cystic fibrosis, in different oxygen environments. Furthermore, we have mimicked the bacterial reinoculation of the aerobic compartments (lower respiratory tract) from the anaerobic compartments (cystic fibrosis sinuses) following an antibiotic treatment. This effect is hypothesised as the one on the main reasons for recurrent lung infections in cystic fibrosis patients. PMID:23908680

  8. Microfluidic strategies for understanding the mechanics of cells and cell-mimetic systems

    PubMed Central

    Dahl, Joanna B.; Lin, Jung-Ming G.; Muller, Susan J.; Kumar, Sanjay

    2016-01-01

    Microfluidic systems are attracting increasing interest for the high-throughput measurement of cellular biophysical properties and for the creation of engineered cellular microenvironments. Here we review recent applications of microfluidic technologies to the mechanics of living cells and synthetic cell-mimetic systems. We begin by discussing the use of microfluidic devices to dissect the mechanics of cellular mimics such as capsules and vesicles. We then explore applications to circulating cells, including erythrocytes and other normal blood cells, and rare populations with potential disease diagnostic value, such as circulating tumor cells. We conclude by discussing how microfluidic devices have been used to investigate the mechanics, chemotaxis, and invasive migration of adherent cells. In these ways, microfluidic technologies represent an increasingly important toolbox for investigating cellular mechanics and motility at high throughput and in a format that lends itself to clinical translation. PMID:26134738

  9. DNA mutation detection and analysis using miniaturized microfluidic systems.

    PubMed

    Handal, Maria I; Ugaz, Victor M

    2006-01-01

    Identification of genetic sequence variations occurring on a population-wide scale is key to unraveling the complex interactions that are the underlying cause of many medical disorders and diseases. A critical need exists, however, for advanced technology to enable DNA mutation analysis to be performed with significantly higher throughput and at significantly lower cost than is currently attainable. Microfluidic systems offer an attractive platform to address these needs by combining the ability to perform rapid analysis with a simplified device format that can be inexpensively mass-produced. This paper will review recent progress toward developing these next-generation systems and discuss challenges associated with adapting these technologies for routine laboratory use.

  10. Enhanced optical chromatography in a PDMS microfluidic system

    NASA Astrophysics Data System (ADS)

    Terray, A.; Arnold, J.; Hart, S. J.

    2005-12-01

    The purely refractive index driven separation of uniformly sized polystyrene, n = 1.59 and poly(methylmethacrylate), n = 1.49 in an optical chromatography system has been enhanced through the incorporation of a custom poly(dimethysiloxane) (PDMS) microfluidic system. A customized channel geometry was used to create separate regions with different linear flow velocities tailored to the specific application. These separate flow regions were then used to expose the entities in the separation to different linear flow velocities thus enhancing their separation relative to the same separation in a constant velocity flow environment. A microbiological sample containing spores of the biological warfare agent, Bacillus anthracis, and a common environmental interferent, mulberry pollen, was investigated to test the use of tailored velocity regions. These very different samples were analyzed simultaneously only through the use of tailored velocity regions.

  11. CAD system for automatic analysis of CT perfusion maps

    NASA Astrophysics Data System (ADS)

    Hachaj, T.; Ogiela, M. R.

    2011-03-01

    In this article, authors present novel algorithms developed for the computer-assisted diagnosis (CAD) system for analysis of dynamic brain perfusion, computer tomography (CT) maps, cerebral blood flow (CBF), and cerebral blood volume (CBV). Those methods perform both quantitative analysis [detection and measurement and description with brain anatomy atlas (AA) of potential asymmetries/lesions] and qualitative analysis (semantic interpretation of visualized symptoms). The semantic interpretation (decision about type of lesion: ischemic/hemorrhagic, is the brain tissue at risk of infraction or not) of visualized symptoms is done by, so-called, cognitive inference processes allowing for reasoning on character of pathological regions based on specialist image knowledge. The whole system is implemented in.NET platform (C# programming language) and can be used on any standard PC computer with.NET framework installed.

  12. Microfluidic cytometers with integrated on-chip optical systems for red blood cell and platelet counting.

    PubMed

    Zhao, Yingying; Li, Qin; Hu, Xiaoming; Lo, Yuhwa

    2016-11-01

    A microfluidic cytometer with integrated on-chip optical systems was designed for red blood cell (RBC) and platelet (PLT) counting. The design, fabrication, and characterization of the microfluidic cytometer with on-chip optical signal detection were described. With process using only a single mask, the device that integrates optical fibers and on-chip microlens with microfluidic channels on a polydimethylsiloxane layer by standard soft photolithography. This compact structure increased the sensitivity of the device and eliminated time-consuming free-space optical alignments. The microfluidic cytometer was used to count red blood cells and platelets. Forward scatter and extinction were collected simultaneously for each cell. Experimental results indicated that the microfluidic cytometer exhibited comparable performance with a conventional cytometer and demonstrated superior capacity to detect on-chip optical signals in a highly compact, simple, truly portable, and low-cost format that is well suitable for point-of-care clinical diagnostics.

  13. Design of a high-throughput flow perfusion bioreactor system for tissue engineering.

    PubMed

    Dahlin, Rebecca L; Meretoja, Ville V; Ni, Mengwei; Kasper, F Kurtis; Mikos, Antonios G

    2012-10-01

    Flow perfusion culture is used in many areas of tissue engineering and offers several key advantages. However, one challenge to these cultures is the relatively low-throughput nature of perfusion bioreactors. Here, a flow perfusion bioreactor with increased throughput was designed and built for tissue engineering. This design uses an integrated medium reservoir and flow chamber in order to increase the throughput, limit the volume of medium required to operate the system, and simplify the assembly and operation.

  14. Microfluidic System Simulation Including the Electro-Viscous Effect

    NASA Technical Reports Server (NTRS)

    Rojas, Eileen; Chen, C. P.; Majumdar, Alok

    2007-01-01

    This paper describes a practical approach using a general purpose lumped-parameter computer program, GFSSP (Generalized Fluid System Simulation Program) for calculating flow distribution in a network of micro-channels including electro-viscous effects due to the existence of electrical double layer (EDL). In this study, an empirical formulation for calculating an effective viscosity of ionic solutions based on dimensional analysis is described to account for surface charge and bulk fluid conductivity, which give rise to electro-viscous effect in microfluidics network. Two dimensional slit micro flow data was used to determine the model coefficients. Geometry effect is then included through a Poiseuille number correlation in GFSSP. The bi-power model was used to calculate flow distribution of isotropically etched straight channel and T-junction microflows involving ionic solutions. Performance of the proposed model is assessed against experimental test data.

  15. A robust microfluidic in vitro cell perifusion system.

    PubMed

    Morris, Christina; Banks, Dylan J; Gaweda, Lukasz; Scott, Steve; Zhu, Xi Xi; Panico, Maria; Georgiou, Pantelis; Toumazou, Christofer

    2011-01-01

    We present here a robust microfluidic cell perifusion device for in vitro primary tissue cell secretion studies. This system increases the sample concentration to perifusion volume ratio by an order of magnitude compared with standard multi-well plate static incubation assays. Further, this device achieves physiologically relevant flow rates, pressures, and temperature. It has been manufactured with typical machining facilities, principally drilling and milling. No specialist clean room equipment is required to replicate it. We show its capability here with hormone perifusion experiments on primary pancreatic tissue from mice. This device can increase cell secretion concentrations by up to a factor of 20, allowing for the first time the direct measurement of islet glucagon using mass spectrometry.

  16. External-integrated biomimetic micropump for microfluidic system

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Liu, Chong; Li, Jingmin; Xu, Zheng; Gan, Lu; Li, Tao; Zhou, Lijie; Ma, Yahui; Zhang, Hao; Zhang, Kaiping

    2014-07-01

    An external-integrated biomimetic micropump for a microfluidic system is demonstrated. An "artificial leaf" is constituted, which mimics the stomatal transpiration process in plants and utilizes the negative pressure generated to drive the fluid flow. The biomimetic micropump integrated an SU-8 film with a micropore array, agarose gel, a flow rate control unit, and additional necessary operating auxiliaries. SU-8 film with micropores and agarose gel is used to mimic the stomata and the mesophyll cells in a leaf, respectively. The flow rate control unit can change the flow rate of the micropump by adjusting the number of micropores that participate in transpiration. Additional necessary operating auxiliaries can fix a microchip, provide a continuous fluid supply, and speed up the fluid flow rate. Experiments on a microchip are conducted to evaluate the performance of the micropump platform. Results have shown that the flow rate of the micropump can be increased by accelerating the wind speed or raising the temperature.

  17. A hybrid microfluidic platform for cell-based assays via diffusive and convective trans-membrane perfusion

    PubMed Central

    Vereshchagina, Elizaveta; Mc Glade, Declan; Glynn, Macdara; Ducrée, Jens

    2013-01-01

    We present a novel 3D hybrid assembly of a polymer microfluidic chip with polycarbonate track-etched membrane (PCTEM) enabling membrane-supported cell culture. Two chip designs have been developed to establish either diffusive or convective reagent delivery using the integrated PCTEM. While it is well suited to a range of cell-based assays, we specifically employ this platform for the screening of a common antitumor chemotoxic agent (mitomycin C – MMC) on the HL60 myeloid leukemia cell line. The toxic activity of MMC is based on the generation of severe DNA damage in the cells. Using either mode of operation, the HL60 cells were cultured on-chip before, during, and after exposure to MMC at concentrations ranging from 0 to 50 μM. Cell viability was analysed off-chip by the trypan blue dye exclusion assay. The results of the on-chip viability assay were found to be consistent with those obtained off-chip and indicated ca. 40% cell survival at MMC concentration of 50 μM. The catalogue of capabilities of the here described cell assay platform comprises of (i) the culturing of cells either under shear-free conditions or under induced through-membrane flows, (ii) the tight time control of the reagent exposure, (iii) the straightforward assembly of devices, (iv) the flexibility on the choice of the membrane, and, prospectively, (v) the amenability for large-scale parallelization. PMID:24404021

  18. Rapid prototyping of microfluidic systems using a PDMS/polymer tape composite.

    PubMed

    Kim, Jungkyu; Surapaneni, Rajesh; Gale, Bruce K

    2009-05-07

    Rapid prototyping of microfluidic systems using a combination of double-sided tape and PDMS (polydimethylsiloxane) is introduced. PDMS is typically difficult to bond using adhesive tapes due to its hydrophobic nature and low surface energy. For this reason, PDMS is not compatible with the xurography method, which uses a knife plotter and various adhesive coated polymer tapes. To solve these problems, a PDMS/tape composite was developed and demonstrated in microfluidic applications. The PDMS/tape composite was created by spinning it to make a thin layer of PDMS over double-sided tape. Then the PDMS/tape composite was patterned to create channels using xurography, and bonded to a PDMS slab. After removing the backing paper from the tape, a complete microfluidic system could be created by placing the construct onto nearly any substrate; including glass, plastic or metal-coated glass/silicon substrates. The bond strength was shown to be sufficient for the pressures that occur in typical microfluidic channels used for chemical or biological analysis. This method was demonstrated in three applications: standard microfluidic channels and reactors, a microfluidic system with an integrated membrane, and an electrochemical biosensor. The PDMS/tape composite rapid prototyping technique provides a fast and cost effective fabrication method and can provide easy integration of microfluidic channels with sensors and other components without the need for a cleanroom facility.

  19. Perfusion Electronic Record Documentation Using Epic Systems Software.

    PubMed

    Riley, Jeffrey B; Justison, George A

    2015-12-01

    The authors comment on Steffens and Gunser's article describing the University of Wisconsin adoption of the Epic anesthesia record to include perfusion information from the cardiopulmonary bypass patient experience. We highlight the current-day lessons and the valuable quality and safety principles the Wisconsin-Epic model anesthesia-perfusion record provides.

  20. Microfluidic on-chip fluorescence-activated interface control system.

    PubMed

    Haiwang, Li; Nguyen, N T; Wong, T N; Ng, S L

    2010-11-22

    A microfluidic dynamic fluorescence-activated interface control system was developed for lab-on-a-chip applications. The system consists of a straight rectangular microchannel, a fluorescence excitation source, a detection sensor, a signal conversion circuit, and a high-voltage feedback system. Aqueous NaCl as conducting fluid and aqueous glycerol as nonconducting fluid were introduced to flow side by side into the straight rectangular microchannel. Fluorescent dye was added to the aqueous NaCl to work as a signal representing the interface position. Automatic control of the liquid interface was achieved by controlling the electroosmotic effect that exists only in the conducting fluid using a high-voltage feedback system. A LABVIEW program was developed to control the output of high-voltage power supply according the actual interface position, and then the interface position is modified as the output of high-voltage power supply. At last, the interface can be moved to the desired position automatically using this feedback system. The results show that the system presented in this paper can control an arbitrary interface location in real time. The effects of viscosity ratio, flow rates, and polarity of electric field were discussed. This technique can be extended to switch the sample flow and droplets automatically.

  1. Microfluidic Pneumatic Logic Circuits and Digital Pneumatic Microprocessors for Integrated Microfluidic Systems

    PubMed Central

    Rhee, Minsoung

    2010-01-01

    We have developed pneumatic logic circuits and microprocessors built with microfluidic channels and valves in polydimethylsiloxane (PDMS). The pneumatic logic circuits perform various combinational and sequential logic calculations with binary pneumatic signals (atmosphere and vacuum), producing cascadable outputs based on Boolean operations. A complex microprocessor is constructed from combinations of various logic circuits and receives pneumatically encoded serial commands at a single input line. The device then decodes the temporal command sequence by spatial parallelization, computes necessary logic calculations between parallelized command bits, stores command information for signal transportation and maintenance, and finally executes the command for the target devices. Thus, such pneumatic microprocessors will function as a universal on-chip control platform to perform complex parallel operations for large-scale integrated microfluidic devices. To demonstrate the working principles, we have built 2-bit, 3-bit, 4-bit, and 8-bit microprecessors to control various target devices for applications such as four color dye mixing, and multiplexed channel fluidic control. By significantly reducing the need for external controllers, the digital pneumatic microprocessor can be used as a universal on-chip platform to autonomously manipulate microfluids in a high throughput manner. PMID:19823730

  2. Microfluidic pneumatic logic circuits and digital pneumatic microprocessors for integrated microfluidic systems.

    PubMed

    Rhee, Minsoung; Burns, Mark A

    2009-11-07

    We have developed pneumatic logic circuits and microprocessors built with microfluidic channels and valves in polydimethylsiloxane (PDMS). The pneumatic logic circuits perform various combinational and sequential logic calculations with binary pneumatic signals (atmosphere and vacuum), producing cascadable outputs based on Boolean operations. A complex microprocessor is constructed from combinations of various logic circuits and receives pneumatically encoded serial commands at a single input line. The device then decodes the temporal command sequence by spatial parallelization, computes necessary logic calculations between parallelized command bits, stores command information for signal transportation and maintenance, and finally executes the command for the target devices. Thus, such pneumatic microprocessors will function as a universal on-chip control platform to perform complex parallel operations for large-scale integrated microfluidic devices. To demonstrate the working principles, we have built 2-bit, 3-bit, 4-bit, and 8-bit microprocessors to control various target devices for applications such as four color dye mixing, and multiplexed channel fluidic control. By significantly reducing the need for external controllers, the digital pneumatic microprocessor can be used as a universal on-chip platform to autonomously manipulate microfluids in a high throughput manner.

  3. Integrated Microfluidics/Electrochemical Sensor System for Field-Monitoring of Toxic Metals

    SciTech Connect

    Lin, Yuehe; Matson, Dean W.; Bennett, Wendy D.; Thrall, K D.; Timchalk, Chuck; W. Ehrfeld

    2000-01-01

    Discusses a miniaturized analytical system based on a microfluidics/electrochemical detection scheme. Individual modules, such as microfabricated piezoelectrically actuated pumps, a micro-membrane separator and a microelectrochemical cell will be integrated onto a portable platform.

  4. A microfluidic system incorporated with peptide/Pd nanowires for heterogeneous catalytic reactions.

    PubMed

    Ryoo, Hyang-Im; Lee, Joon Seok; Park, Chan Beum; Kim, Dong-Pyo

    2011-02-07

    Highly stable diphenylalanine peptide nanowires were selectively self-assembled in the reaction zone of a microfluidic system and applied for microchemical hydrogenation and Suzuki coupling reactions through the hybridization of Pd nanoparticles.

  5. Modular integration of electronics and microfluidic systems using flexible printed circuit boards.

    PubMed

    Wu, Amy; Wang, Lisen; Jensen, Erik; Mathies, Richard; Boser, Bernhard

    2010-02-21

    Microfluidic systems offer an attractive alternative to conventional wet chemical methods with benefits including reduced sample and reagent volumes, shorter reaction times, high-throughput, automation, and low cost. However, most present microfluidic systems rely on external means to analyze reaction products. This substantially adds to the size, complexity, and cost of the overall system. Electronic detection based on sub-millimetre size integrated circuits (ICs) has been demonstrated for a wide range of targets including nucleic and amino acids, but deployment of this technology to date has been limited due to the lack of a flexible process to integrate these chips within microfluidic devices. This paper presents a modular and inexpensive process to integrate ICs with microfluidic systems based on standard printed circuit board (PCB) technology to assemble the independently designed microfluidic and electronic components. The integrated system can accommodate multiple chips of different sizes bonded to glass or PDMS microfluidic systems. Since IC chips and flex PCB manufacturing and assembly are industry standards with low cost, the integrated system is economical for both laboratory and point-of-care settings.

  6. Cell Separation by Non-Inertial Force Fields in Microfluidic Systems

    PubMed Central

    Tsutsui, Hideaki; Ho, Chih-Ming

    2009-01-01

    Cell and microparticle separation in microfluidic systems has recently gained significant attention in sample preparations for biological and chemical studies. Microfluidic separation is typically achieved by applying differential forces on the target particles to guide them into different paths. This paper reviews basic concepts and novel designs of such microfluidic separators with emphasis on the use of non-inertial force fields, including dielectrophoretic force, optical gradient force, magnetic force, and acoustic primary radiation force. Comparisons of separation performances with discussions on physiological effects and instrumentation issues toward point-of-care devices are provided as references for choosing appropriate separation methods for various applications. PMID:20046897

  7. Moving droplets between closed and open microfluidic systems.

    PubMed

    Wang, Weiqiang; Jones, Thomas B

    2015-05-21

    In electric-field-mediated droplet microfluidics, there are two distinct architectures - closed systems using parallel-plate electrodes and open systems using coplanar electrodes fabricated on an open substrate. An architecture combining both closed and open systems on a chip would facilitate many of the chemical and biological processes now envisioned for the laboratory on a chip. To accomplish such an integration requires a means to move droplets back and forth between the two. This paper presents an investigation of the requirements for such manipulation of both water and oil droplets. The required wetting conditions for a droplet to cross the open/closed boundary is revealed by a force balance analysis and predictions of this model are compared to experimental results. Water droplets can be moved between closed and open systems by electrowetting actuation; droplet detachment from the upper plate is facilitated by the use of beveled edge. The force model predicts that driving an oil droplet from a closed to an open structure requires an oleophobic surface. This prediction has been tested and confirmed using <100> silicon wafers made oleophobic by re-entrant microstructures etched into the surface.

  8. Printable microfluidic systems using pressure sensitive adhesive material for biosensing devices.

    PubMed

    Wang, Xin; Nilsson, David; Norberg, Petronella

    2013-09-01

    In biosensors with a fluid analyte, the integration of a microfluidic system, which guides the analyte into the sensing area, is critical. Quicker and economical ways to build up microfluidic systems will make point of care diagnostics viable. Printing is a low-cost technology that is increasingly used in emerging organic and flexible electronics and biosensors. In this paper, we present printed fluidic systems on flexible substrates made with pressure sensitive adhesive materials. Printable pressure sensitive adhesive materials have been used for making microfluidic systems. Flexible substrates have been used, and two types of adhesive materials, one thermally dried and another UV curable, have been tested. Top sealing layer was laminated directly on top of the printed microfluidic structure. Flow tests were done with deionized water. Flow tests with deionized water show that both adhesive materials are suitable for capillary flow driven fluidic devices. Flow test using water as dielectric material was also done successfully on a printed electrolyte gated organic field effect transistor with an integrated microfluidic system. Due to its ease of process and low cost, printed microfluidic system is believed to find more applications in biosensing devices. This article is part of a Special Issue entitled Organic Bioelectronics-Novel Applications in Biomedicine. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. 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.

  10. 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.

  11. Syringe-pump-induced fluctuation in all-aqueous microfluidic system implications for flow rate accuracy.

    PubMed

    Li, Zida; Mak, Sze Yi; Sauret, Alban; Shum, Ho Cheung

    2014-02-21

    We report a new method to display the minute fluctuations induced by syringe pumps on microfluidic flows by using a liquid-liquid system with an ultralow interfacial tension. We demonstrate that the stepper motor inside the pump is a source of fluctuations in microfluidic flows by comparing the frequencies of the ripples observed at the interface to that of the pulsation of the stepper motor. We also quantify the fluctuations induced at different flow rates, using syringes of different diameters, and using different syringe pumps with different advancing distances per step. Our work provides a way to predict the frequency of the fluctuation that the driving syringe pump induces on a microfluidic system and suggests that syringe pumps can be a source of fluctuations in microfluidic flows, thus contributing to the polydispersity of the resulting droplets.

  12. 3D Droplet Microfluidic Systems for High-Throughput Biological Experimentation.

    PubMed

    Kang, Dong-Ku; Gong, Xiuqing; Cho, Soongwon; Kim, Jin-young; Edel, Joshua B; Chang, Soo-Ik; Choo, Jaebum; deMello, Andrew J

    2015-11-03

    Herein, we describe the development of a multilayer droplet microfluidic system for creating concentration gradients and generating microdroplets of varying composition for high-throughput biochemical and cell-based screening applications. The 3D droplet-based microfluidic device consists of multiple PDMS layers, which are used to generate logarithmic concentration gradient reagent profiles. Parallel flow focusing structures are used to form picoliter-sized droplets of defined volumes but of varying composition. As proof of concept, we demonstrate rapid enzymatic activity assays and drug cytotoxicity assays on bacteria. The 3D droplet-based microfluidic platform has the potential to allow for high-efficiency and high-throughput analysis, overcoming the structural limitations of single layer microfluidic systems.

  13. Functional characterisation and application of an ex vivo perfusion-superfusion system in murine airways.

    PubMed

    Cheah, Esther Y; Mann, Tracy S; Burcham, Philip C; Henry, Peter J

    The aim of this study was to develop two dynamic ex vivo airway explant systems, a perfusion-superfusion system and a ventilation-superfusion system, for the study of toxic airborne substances, such as the prevalent smoke constituent acrolein. Mouse isolated tracheal segments were perfused with physiological media or ventilated with humidified air at 37°C to mimic dynamic flow conditions, and superfused with media over the exterior surface. At selected time points, the histological and functional integrity of segments was evaluated. The perfusion-superfusion system was subsequently used to examine mucin secretory responses elicited by acrolein in airways in which mucous metaplasia had been induced with lipopolysaccharide (LPS; 1μgml(-1)) prior to 24h of media perfusion, followed by stimulation with acrolein or ATP for 15min. Epithelial mucin levels were determined by quantitative analysis of periodic acid-Schiff's reagent (PAS)-stained sections. Epithelial morphology was successfully preserved in the perfusion-superfusion and ventilation-superfusion systems for at least 24h and up to 18h, respectively. At these time points, the contractile and relaxation responses of perfused and ventilated tracheal segments to carbachol, the neuropeptide substance P, and the prostanoid PGE2 were also preserved. Using the perfusion-superfusion system, acute exposure to acrolein caused a dose-dependent reduction in the levels of PAS-positive mucin stores induced by LPS, consistent with mucin secretion. Both the perfusion-superfusion and ventilation-superfusion systems successfully preserved the viability of mouse isolated tracheal segments on a histological and functional level, and the perfusion-superfusion system was used to characterise the mucin secretory responses elicited by acrolein. Thus, this system may be a useful model through which to conduct further toxicological studies in mammalian airways. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Preprogrammed capillarity to passively control system-level sequential and parallel microfluidic flows.

    PubMed

    Kim, Sung-Jin; Paczesny, Sophie; Takayama, Shuichi; Kurabayashi, Katsuo

    2013-06-07

    In microfluidics, capillarity-driven solution flow is often beneficial, owing to its inherently spontaneous motion. However, it is commonly perceived that, in an integrated microfluidic system, the passive capillarity control alone can hardly achieve well-controlled sequential and parallel flow of multiple solutions. Despite this common notion, we hereby demonstrate system-level sequential and parallel microfluidic flow processing by fully passive capillarity-driven control. After manual loading of solutions with a pipette, a network of microfluidic channels passively regulates the flow timing of the multiple solution menisci in a sequential and synchronous manner. Also, use of auxiliary channels and preprogramming of inlet-well meniscus pressure and channel fluidic conductance allow for controlling the flow direction of multiple solutions in our microfluidic system. With those components orchestrated in a single device chip, we show preprogrammed flow control of 10 solutions. The demonstrated system-level flow control proves capillarity as a useful means even for sophisticated microfluidic processing without any actively controlled valves and pumps.

  15. Preprogrammed capillarity to passively control system-level sequential and parallel microfluidic flows

    PubMed Central

    Kim, Sung-Jin; Paczesny, Sophie; Takayama, Shuichi; Kurabayashi, Katsuo

    2013-01-01

    In microfluidics, capillarity-driven solution flow is often beneficial, owing to its inherently spontaneous motion. However, it is commonly perceived that, in an integrated microfluidic system, the passive capillarity control alone can hardly achieve well-controlled sequential and parallel flow of multiple solutions. Despite this common notion, we hereby demonstrate system-level sequential and parallel microfluidic flow processing by fully passive capillarity-driven control. After manual loading of solutions with a pipette, a network of microfluidic channels passively regulates the flow timing of the multiple solution menisci in a sequential and synchronous manner. Also, use of auxiliary channels and preprogramming of inlet-well meniscus pressure and channel fluidic conductance allow for controlling the flow direction of multiple solutions in our microfluidic system. With those components orchestrated in a single device chip, we show preprogrammed flow control of 10 solutions. The demonstrated system-level flow control proves capillarity as a useful means even for sophisticated microfluidic processing without any actively controlled valves and pumps. PMID:23598742

  16. Experimental Studies of Surface-Driven Capillary Flow in PMMA Microfluidic Devices Prepared by Direct Bonding Technique and Passive Separation of Microparticles in Microfluidic Laboratory-On Systems

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Subhadeep; Banerjee, J. P.; Mathur, Ashish; Tweedie, M.; McLaughlin, J. A.; Roy, Susanta Sinha

    2015-05-01

    Proper bonding technique is investigated to achieve leakage-free surface-driven capillary flow in polymethylmethacrylate (PMMA) microfluidic devices. SU-8-based silicon stamp is fabricated by maskless lithography. This stamp is used to produce PMMA microchannel structure by hot embossing lithography. A direct bonding technique is mainly employed for leakage-free sealing inside PMMA microfluidic devices. The effect of surface wettability on surface-driven capillary flow is also investigated in PMMA microfluidic devices. The separation of polystyrene microparticles in PMMA laboratory-on-a-chip systems is investigated with the reduction of separation time by air dielectric barrier discharge (DBD) plasma processing of channel surfaces. This study is useful to fabricate the microfluidic laboratory-on-a-chip systems and to understand the surface-driven capillary flow.

  17. Microfluidics on compliant substrates: recent developments in foldable and bendable devices and system packaging

    NASA Astrophysics Data System (ADS)

    Gray, Bonnie L.

    2012-04-01

    Microfluidics is revolutionizing laboratory methods and biomedical devices, offering new capabilities and instrumentation in multiple areas such as DNA analysis, proteomics, enzymatic analysis, single cell analysis, immunology, point-of-care medicine, personalized medicine, drug delivery, and environmental toxin and pathogen detection. For many applications (e.g., wearable and implantable health monitors, drug delivery devices, and prosthetics) mechanically flexible polymer devices and systems that can conform to the body offer benefits that cannot be achieved using systems based on conventional rigid substrate materials. However, difficulties in implementing active devices and reliable packaging technologies have limited the success of flexible microfluidics. Employing highly compliant materials such as PDMS that are typically employed for prototyping, we review mechanically flexible polymer microfluidic technologies based on free-standing polymer substrates and novel electronic and microfluidic interconnection schemes. Central to these new technologies are hybrid microfabrication methods employing novel nanocomposite polymer materials and devices. We review microfabrication methods using these materials, along with demonstrations of example devices and packaging schemes that employ them. We review these recent developments and place them in the context of the fields of flexible microfluidics and conformable systems, and discuss cross-over applications to conventional rigid-substrate microfluidics.

  18. Rapid isolation and detection of cancer cells by utilizing integrated microfluidic systems.

    PubMed

    Lien, Kang-Yi; Chuang, Ying-Hsin; Hung, Lein-Yu; Hsu, Keng-Fu; Lai, Wu-Wei; Ho, Chung-Liang; Chou, Cheng-Yang; Lee, Gwo-Bin

    2010-11-07

    The present study reports a new three-dimensional (3D) microfluidic platform capable of rapid isolation and detection of cancer cells from a large sample volume (e.g. ~1 mL) by utilizing magnetic microbead-based technologies. Several modules, including a 3D microfluidic incubator for the magnetic beads to capture cancer cells, a microfluidic control module for sample transportation and a nucleic acid amplification module for genetic identification, are integrated into this microsystem. With the incorporation of surface-modified magnetic beads, target cancer cells can be specifically recognized and conjugated onto the surface of the antibody-coated magnetic microbeads by utilizing a swirling effect generated by the new 3D microfluidic incubator, followed by isolating and purifying the magnetic complexes via the incorporation of an external magnet and a microfluidic control module, which washes away any unbound waste solution. Experimental results show that over 90% of the target cancer cells can be isolated from a large volume of bio-samples within 10 min in the 3D microfluidic incubator. In addition, the expressed genes associated with ovarian and lung cancer cells can also be successfully amplified by using the on-chip nucleic acid amplification module. More importantly, the detection limit of the developed system is found to be 5 × 10(1) cells mL(-1) for the target cancer cells, indicating that this proposed microfluidic system may be adapted for clinical use for the early detection of cancer cells. Consequently, the proposed 3D microfluidic system incorporated with immunomagnetic beads may provide a promising automated platform for the rapid isolation and detection of cancer cells with a high sensitivity.

  19. Integration of pharmacokinetic and NRF2 system biology models to describe reactive oxygen species production and subsequent glutathione depletion in liver microfluidic biochips after flutamide exposure.

    PubMed

    Leclerc, Eric; Hamon, Jeremy; Legendre, Audrey; Bois, Frederic Y

    2014-10-01

    We present a systems biology analysis of rat primary hepatocytes response after exposure to 10 μM and 100 μM flutamide in liver microfluidic biochips. We coupled an in vitro pharmacokinetic (PK) model of flutamide to a system biology model of its reactive oxygen species (ROS) production and scavenging by the Nrf2 regulated glutathione production. The PK model was calibrated using data on flutamide kinetics, hydroxyflutamide and glutathione conjugates formation in microfluidic conditions. The parameters of Nrf2-related gene activities and the subsequent glutathione depletion were calibrated using microarray data from our microfluidic experiments and literature information. Following a 10 μM flutamide exposure, the model predicted a recovery time to baseline levels of glutathione (GSH) and ROS in agreement with our experimental observations. At 100 μM, the model predicted that metabolism saturation led to an important accumulation of flutamide in cells, a high ROS production and complete GSH depletion. The high levels of ROS predicted were consistent with the necrotic switch observed by transcriptomics, and the high cell mortality we had experimentally observed. The model predicted a transition between recoverable GSH depletion and deep GSH depletion at about 12.5 μM of flutamide (single perfusion exposure). Our work shows that in vitro biochip experiments can provide supporting information for complex in silico modeling including data from extra cellular and intra cellular levels. We believe that this approach can be an efficient strategy for a global integrated methodology in predictive toxicology.

  20. On capillary self-focusing in a microfluidic system

    NASA Astrophysics Data System (ADS)

    Hein, M.; Seemann, R.; Afkhami, S.

    2016-12-01

    A computational framework is developed to address capillary self-focusing in step emulsification. The microfluidic system consists of a single shallow and wide microchannel that merges into a deep reservoir. A continuum approach coupled with a volume of fluid method is used to model the capillary self-focusing effect. The original governing equations are reduced using the Hele-Shaw approximation. We show that the interface between the two fluids takes the shape of a neck narrowing in the flow direction just before entering the reservoir, in agreement with our experimental observations. Our computational model relies on the assumption that the pressure at the boundary, where the fluid exits into the reservoir, is the uniform pressure in the reservoir. We investigate this hypothesis by comparing the numerical results with experimental data. We conjecture that the pressure boundary condition becomes important when the width of the neck is comparable to the depth of the microchannel. A correction to the exit pressure boundary condition is then proposed, which is determined by comparison with experimental data. We also present the experimental observations and the numerical results of the transitions of breakup regimes.

  1. Microfluidic system for high throughput characterisation of echogenic particles.

    PubMed

    Rademeyer, Paul; Carugo, Dario; Lee, Jeong Yu; Stride, Eleanor

    2015-01-21

    Echogenic particles, such as microbubbles and volatile liquid micro/nano droplets, have shown considerable potential in a variety of clinical diagnostic and therapeutic applications. The accurate prediction of their response to ultrasound excitation is however extremely challenging, and this has hindered the optimisation of techniques such as quantitative ultrasound imaging and targeted drug delivery. Existing characterisation techniques, such as ultra-high speed microscopy provide important insights, but suffer from a number of limitations; most significantly difficulty in obtaining large data sets suitable for statistical analysis and the need to physically constrain the particles, thereby altering their dynamics. Here a microfluidic system is presented that overcomes these challenges to enable the measurement of single echogenic particle response to ultrasound excitation. A co-axial flow focusing device is used to direct a continuous stream of unconstrained particles through the combined focal region of an ultrasound transducer and a laser. Both the optical and acoustic scatter from individual particles are then simultaneously recorded. Calibration of the device and example results for different types of echogenic particle are presented, demonstrating a high throughput of up to 20 particles per second and the ability to resolve changes in particle radius down to 0.1 μm with an uncertainty of less than 3%.

  2. A microfluidic distribution system for an array of hollow microneedles

    NASA Astrophysics Data System (ADS)

    Hoel, Antonin; Baron, Nolwenn; Cabodevila, Gonzalo; Jullien, Marie-Caroline

    2008-06-01

    We report a microfluidic device able to control the ejection of fluid through a matrix of out-of-plane microneedles. The device comprises a matrix of open dispensing units connected to needles and filled by a common filling system. A deformable membrane (e.g. in PDMS) is brought into contact with the dispensing units. Pressure exerted on the deformable membrane closes (and thus individualizes) each dispensing unit and provokes the ejection of the dispensing unit content through the outlets. Sufficient pressure over the deformable membrane ensures that all dispensing units deliver a fixed volume (their content) irrespective of the hydrodynamic pressure outside the dispensing unit outlet. The size of the ensemble matrix of dispensing units, the number of liquid reservoirs, as well as the material can vary depending on the considered application of the device or on the conditions of use. In the present paper, the liquid reservoirs are geometrically identical. The geometrical parameters of the device are optimized to avoid as much dead volume as possible, as it was to handle plasmid DNA solutions which are very expensive. The conception, the fabrication and the experimental results are described in this paper. Our prototype is conceived to inject in a uniform way 10 µl of drug through 100 microneedles distributed over 1 cm2.

  3. A latchable thermally activated phase change actuator for microfluidic systems

    NASA Astrophysics Data System (ADS)

    Richter, Christiane; Sachsenheimer, Kai; Rapp, Bastian E.

    2016-03-01

    Complex microfluidic systems often require a high number of individually controllable active components like valves and pumps. In this paper we present the development and optimization of a latchable thermally controlled phase change actuator which uses a solid/liquid phase transition of a phase change medium and the displacement of the liquid phase change medium to change and stabilize the two states of the actuator. Because the phase change is triggered by heat produced with ohmic resistors the used control signal is an electrical signal. In contrast to pneumatically activated membrane valves this concept allows the individual control of several dozen actuators with only two external pressure lines. Within this paper we show the general working principle of the actuator and demonstrate its general function and the scalability of the concept at an example of four actuators. Additionally we present the complete results of our studies to optimize the response behavior of the actuator - the influence of the heating power as well as the used phase change medium on melting and solidifying times.

  4. Design verification of a compact system for detecting tissue perfusion using bimodal diffuse optical technologies

    NASA Astrophysics Data System (ADS)

    Pakela, Julia M.; Hedrick, Taylor L.; Lee, Seung Yup; Vishwanath, Karthik; Zanfardino, Sara; Chung, Yooree G.; Helton, Michael C.; Kolodziejski, Noah J.; Stapels, Christopher J.; McAdams, Daniel R.; Fernandez, Daniel E.; Christian, James F.; Feinberg, Stephen E.; Mycek, Mary-Ann

    2017-02-01

    It is essential to monitor tissue perfusion during and after reconstructive surgery, as restricted blood flow can result in graft failures. Current clinical procedures are insufficient to monitor tissue perfusion, as they are intermittent and often subjective. To address this unmet clinical need, a compact, low-cost, multimodal diffuse correlation spectroscopy and diffuse reflectance spectroscopy system was developed. We verified system performance via tissue phantoms and experimental protocols for rigorous bench testing. Quantitative data analysis methods were employed and tested to enable the extraction of tissue perfusion parameters. This design verification study assures data integrity in future in vivo studies.

  5. Point-of-care, portable microfluidic blood analyzer system

    NASA Astrophysics Data System (ADS)

    Maleki, Teimour; Fricke, Todd; Quesenberry, J. T.; Todd, Paul W.; Leary, James F.

    2012-03-01

    Recent advances in MEMS technology have provided an opportunity to develop microfluidic devices with enormous potential for portable, point-of-care, low-cost medical diagnostic tools. Hand-held flow cytometers will soon be used in disease diagnosis and monitoring. Despite much interest in miniaturizing commercially available cytometers, they remain costly, bulky, and require expert operation. In this article, we report progress on the development of a battery-powered handheld blood analyzer that will quickly and automatically process a drop of whole human blood by real-time, on-chip magnetic separation of white blood cells (WBCs), fluorescence analysis of labeled WBC subsets, and counting a reproducible fraction of the red blood cells (RBCs) by light scattering. The whole blood (WB) analyzer is composed of a micro-mixer, a special branching/separation system, an optical detection system, and electronic readout circuitry. A droplet of un-processed blood is mixed with the reagents, i.e. magnetic beads and fluorescent stain in the micro-mixer. Valve-less sorting is achieved by magnetic deflection of magnetic microparticle-labeled WBC. LED excitation in combination with an avalanche photodiode (APD) detection system is used for counting fluorescent WBC subsets using several colors of immune-Qdots, while counting a reproducible fraction of red blood cells (RBC) is performed using a laser light scatting measurement with a photodiode. Optimized branching/channel width is achieved using Comsol Multi-Physics™ simulation. To accommodate full portability, all required power supplies (40v, +/-10V, and +3V) are provided via step-up voltage converters from one battery. A simple onboard lock-in amplifier is used to increase the sensitivity/resolution of the pulse counting circuitry.

  6. SERS decoding of micro gold shells moving in microfluidic systems.

    PubMed

    Lee, Saram; Joo, Segyeong; Park, Sejin; Kim, Soyoun; Kim, Hee Chan; Chung, Taek Dong

    2010-05-01

    In this study, in situ surface-enhanced Raman scattering (SERS) decoding was demonstrated in microfluidic chips using novel thin micro gold shells modified with Raman tags. The micro gold shells were fabricated using electroless gold plating on PMMA beads with diameter of 15 microm. These shells were sophisticatedly optimized to produce the maximum SERS intensity, which minimized the exposure time for quick and safe decoding. The shell surfaces produced well-defined SERS spectra even at an extremely short exposure time, 1 ms, for a single micro gold shell combined with Raman tags such as 2-naphthalenethiol and benzenethiol. The consecutive SERS spectra from a variety of combinations of Raman tags were successfully acquired from the micro gold shells moving in 25 microm deep and 75 microm wide channels on a glass microfluidic chip. The proposed functionalized micro gold shells exhibited the potential of an on-chip microfluidic SERS decoding strategy for micro suspension array.

  7. Analysis system for characterisation of simple, low-cost microfluidic components

    NASA Astrophysics Data System (ADS)

    Smith, Suzanne; Naidoo, Thegaran; Nxumalo, Zandile; Land, Kevin; Davies, Emlyn; Fourie, Louis; Marais, Philip; Roux, Pieter

    2014-06-01

    There is an inherent trade-off between cost and operational integrity of microfluidic components, especially when intended for use in point-of-care devices. We present an analysis system developed to characterise microfluidic components for performing blood cell counting, enabling the balance between function and cost to be established quantitatively. Microfluidic components for sample and reagent introduction, mixing and dispensing of fluids were investigated. A simple inlet port plugging mechanism is used to introduce and dispense a sample of blood, while a reagent is released into the microfluidic system through compression and bursting of a blister pack. Mixing and dispensing of the sample and reagent are facilitated via air actuation. For these microfluidic components to be implemented successfully, a number of aspects need to be characterised for development of an integrated point-of-care device design. The functional components were measured using a microfluidic component analysis system established in-house. Experiments were carried out to determine: 1. the force and speed requirements for sample inlet port plugging and blister pack compression and release using two linear actuators and load cells for plugging the inlet port, compressing the blister pack, and subsequently measuring the resulting forces exerted, 2. the accuracy and repeatability of total volumes of sample and reagent dispensed, and 3. the degree of mixing and dispensing uniformity of the sample and reagent for cell counting analysis. A programmable syringe pump was used for air actuation to facilitate mixing and dispensing of the sample and reagent. Two high speed cameras formed part of the analysis system and allowed for visualisation of the fluidic operations within the microfluidic device. Additional quantitative measures such as microscopy were also used to assess mixing and dilution accuracy, as well as uniformity of fluid dispensing - all of which are important requirements towards the

  8. Continuous synthesis of zinc oxide nanoparticles in a microfluidic system for photovoltaic application

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Leem, Juyoung; Yoon, Sang Youl; Sung, Hyung Jin

    2014-02-01

    This study describes the synthesis of zinc oxide nanoparticles (ZnO NPs) using a microfluidic system. A continuous and efficient synthetic process was developed based on a microfluidic reactor in which was implemented a time pulsed mixing method that had been optimized using numerical simulations and experimental methods. Numerical simulations revealed that efficient mixing conditions could be obtained over the frequency range 5-15 Hz. This system used ethanol solutions containing 30 mM sodium hydroxide (NaOH) or 10 mM dehydrated zinc acetate (Zn(OAc)2) under 5 Hz pulsed conditions, which provided the optimal mixing performance conditions. The ZnO NPs prepared using the microfluidic synthetic system or batch-processed system were validated by several analytical methods, including transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), UV/VIS NIR and zeta (ζ) potential analysis. Bulk-heterojunction organic photovoltaic cells were fabricated with the synthesized ZnO NPs to investigate the practicability and compared with batch-process synthesized ZnO NPs. The results showed that microfluidic synthesized ZnO NPs had good preservability and stability in working solution and the synthetic microfluidic system provided a low-cost, environmentally friendly approach to the continuous production of ZnO NPs.

  9. Continuous synthesis of zinc oxide nanoparticles in a microfluidic system for photovoltaic application.

    PubMed

    Kang, Hyun Wook; Leem, Juyoung; Yoon, Sang Youl; Sung, Hyung Jin

    2014-03-07

    This study describes the synthesis of zinc oxide nanoparticles (ZnO NPs) using a microfluidic system. A continuous and efficient synthetic process was developed based on a microfluidic reactor in which was implemented a time pulsed mixing method that had been optimized using numerical simulations and experimental methods. Numerical simulations revealed that efficient mixing conditions could be obtained over the frequency range 5-15 Hz. This system used ethanol solutions containing 30 mM sodium hydroxide (NaOH) or 10 mM dehydrated zinc acetate (Zn(OAc)2) under 5 Hz pulsed conditions, which provided the optimal mixing performance conditions. The ZnO NPs prepared using the microfluidic synthetic system or batch-processed system were validated by several analytical methods, including transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), UV/VIS NIR and zeta (ζ) potential analysis. Bulk-heterojunction organic photovoltaic cells were fabricated with the synthesized ZnO NPs to investigate the practicability and compared with batch-process synthesized ZnO NPs. The results showed that microfluidic synthesized ZnO NPs had good preservability and stability in working solution and the synthetic microfluidic system provided a low-cost, environmentally friendly approach to the continuous production of ZnO NPs.

  10. Multilayer microfluidic systems with indium-tin-oxide microelectrodes for studying biological cells

    NASA Astrophysics Data System (ADS)

    Wu, Hsiang-Chiu; Lyau, Jia-Bo; Lin, Min-Hsuan; Chuang, Yung-Jen; Chen, Hsin

    2017-07-01

    Contemporary semiconductor and micromachining technologies have been exploited to develop lab-on-a-chip microsystems, which enable parallel and efficient experiments in molecular and cellular biology. In these microlab systems, microfluidics play an important role for automatic transportation or immobilization of cells and bio-molecules, as well as for separation or mixing of different chemical reagents. However, seldom microlab systems allow both morphology and electrophysiology of biological cells to be studied in situ. This kind of study is important, for example, for understanding how neuronal networks grow in response to environmental stimuli. To fulfill this application need, this paper investigates the possibility of fabricating multi-layer photoresists as microfluidic systems directly above a glass substrate with indium-tin-oxide (ITO) electrodes. The microfluidic channels are designed to guide and trap biological cells on top of ITO electrodes, through which the electrical activities of cells can be recorded or elicited. As both the microfluidic system and ITO electrodes are transparent, the cellular morphology is observable easily during electrophysiological studies. Two fabrication processes are proposed and compared. One defines the structure and curing depth of each photoresist layer simply by controlling the exposure time in lithography, while the other further utilizes a sacrificial layer to defines the structure of the bottom layer. The fabricated microfluidic system is proved bio-compatible and able to trap blood cells or neurons. Therefore, the proposed microsystem will be useful for studying cultured cells efficiently in applications such as drug-screening.

  11. [Micro-droplet characterization and its application for amino acid detection in droplet microfluidic system].

    PubMed

    Yuan, Huiling; Dong, Libing; Tu, Ran; Du, Wenbin; Ji, Shiru; Wang, Qinhong

    2014-01-01

    Recently, the droplet microfluidic system attracts interests due to its high throughput and low cost to detect and screen. The picoliter micro-droplets from droplet microfluidics are uniform with respect to the size and shape, and could be used as monodispensed micro-reactors for encapsulation and detection of single cell or its metabolites. Therefore, it is indispensable to characterize micro-droplet and its application from droplet microfluidic system. We first constructed the custom-designed droplet microfluidic system for generating micro-droplets, and then used the micro-droplets to encapsulate important amino acids such as glutamic acid, phenylalanine, tryptophan or tyrosine to test the droplets' properties, including the stability, diffusivity and bio-compatibility for investigating its application for amino acid detection and sorting. The custom-designed droplet microfluidic system could generate the uniformed micro-droplets with a controllable size between 20 to 50 microm. The micro-droplets could be stable for more than 20 h without cross-contamination or fusion each other. The throughput of detection and sorting of the system is about 600 micro-droplets per minute. This study provides a high-throughput platform for the analysis and screening of amino acid-producing microorganisms.

  12. Microfluidic organs-on-chips.

    PubMed

    Bhatia, Sangeeta N; Ingber, Donald E

    2014-08-01

    An organ-on-a-chip is a microfluidic cell culture device created with microchip manufacturing methods that contains continuously perfused chambers inhabited by living cells arranged to simulate tissue- and organ-level physiology. By recapitulating the multicellular architectures, tissue-tissue interfaces, physicochemical microenvironments and vascular perfusion of the body, these devices produce levels of tissue and organ functionality not possible with conventional 2D or 3D culture systems. They also enable high-resolution, real-time imaging and in vitro analysis of biochemical, genetic and metabolic activities of living cells in a functional tissue and organ context. This technology has great potential to advance the study of tissue development, organ physiology and disease etiology. In the context of drug discovery and development, it should be especially valuable for the study of molecular mechanisms of action, prioritization of lead candidates, toxicity testing and biomarker identification.

  13. Microfluidic module system with piezo driven microvalve for synthesis of radiopharmaceutical products.

    PubMed

    Scheuenpflug, Michael; Guenther, Daniel; Irlinger, Franz; Lueth, Tim

    2007-01-01

    This article presents a novel microfluidic module system for the synthesis of radiopharmaceutical products. As a main function a piezo-actuated diaphragm valve is produced with rapid prototyping procedures. A system for the automatic characterization of microvalves is described. The built microvalve is characterized by a very high throughput and low leakage rate even for gaseous media. The valve as other passive modules like mixer elements can be easily combined to a microfluidic system. The system makes the application of radiopharmaceutical products more effective and less costly intensive.

  14. How to fabricate robust microfluidic systems for a dollar

    NASA Astrophysics Data System (ADS)

    Lapierre, Florian; Cameron, Neil R.; Oakeshott, John; Peat, Thomas; Zhu, Yonggang

    2013-12-01

    Since the past decade, the interest towards microfluidic devices has sensibly grown due to the wide variety of multidisciplinary applications. One branch of the microfluidic domain consists in the synthesis of various types of emulsions requested by cosmetic, food and biotechnological industries In particular, monodisperse water-in-oil microemulsion synthetised in microfluidic devices are quickly becoming the new generation of emulsions for precise bead control and high surface area. These microemulsions are generally aqueous bioreactors in the form of droplets from 500 nm to 10 μm in diameter, enclosed in an oil environment. An increasing demand for bigger emulsions has led us to investigate new techniques for fabricating fluidic devices allowing a better control over the final size of the droplets. An easy, cheap, reproducible and fast technology for generating emulsions in the range of 100s μm with high throughout (up to mL/h) is reported. Simply using pipette tips and tubing, an innovative microfluidic device was fabricated, able to synthetise water-in-oil emulsions within the range 50 - 500 _μm and double emulsions. These new emulsions are currently used for the synthesis of highly porous polymers beads from High Internal Phase Emulsion (HIPE). These beads will find high potential in 3D cell culture due to their high porosity (up to 90%) and pore size (from 5 to 30μm).

  15. Utilization of the organ care system as ex-vivo lung perfusion after cold storage transportation.

    PubMed

    Mohite, P N; Maunz, O; Popov, A-F; Zych, B; Patil, N P; Simon, A R

    2015-11-01

    The Organ Care System (OCS) allows perfusion and ventilation of the donor lungs under physiological conditions. Ongoing trials to compare preservation with OCS Lung with standard cold storage do not include donor lungs with suboptimal gas exchange and donor lungs treated with OCS following cold storage transportation. We present a case of a 48-yr-old man who received such lungs after cold storage transportation treated with ex-vivo lung perfusion utilizing OCS. © The Author(s) 2015.

  16. A Microfluidic Immunostaining System Enables Quality Assured and Standardized Immunohistochemical Biomarker Analysis

    NASA Astrophysics Data System (ADS)

    Kwon, Seyong; Cho, Chang Hyun; Kwon, Youngmee; Lee, Eun Sook; Park, Je-Kyun

    2017-04-01

    Immunohistochemistry (IHC) plays an important role in biomarker-driven cancer therapy. Although there has been a high demand for standardized and quality assured IHC, it has rarely been achieved due to the complexity of IHC testing and the subjective validation-based process flow of IHC quality control. We present here a microfluidic immunostaining system for the standardization of IHC by creating a microfluidic linearly graded antibody (Ab)-staining device and a reference cell microarray. Unlike conventional efforts, our system deals primarily with the screening of biomarker staining conditions for quantitative quality assurance testing in IHC. We characterized the microfluidic matching of Ab staining intensity using three HER2 Abs produced by different manufacturers. The quality of HER2 Ab was also validated using tissues of breast cancer patients, demonstrating that our system is an efficient and powerful tool for the standardization and quality assurance of IHC.

  17. A Microfluidic Immunostaining System Enables Quality Assured and Standardized Immunohistochemical Biomarker Analysis

    PubMed Central

    Kwon, Seyong; Cho, Chang Hyun; Kwon, Youngmee; Lee, Eun Sook; Park, Je-Kyun

    2017-01-01

    Immunohistochemistry (IHC) plays an important role in biomarker-driven cancer therapy. Although there has been a high demand for standardized and quality assured IHC, it has rarely been achieved due to the complexity of IHC testing and the subjective validation-based process flow of IHC quality control. We present here a microfluidic immunostaining system for the standardization of IHC by creating a microfluidic linearly graded antibody (Ab)-staining device and a reference cell microarray. Unlike conventional efforts, our system deals primarily with the screening of biomarker staining conditions for quantitative quality assurance testing in IHC. We characterized the microfluidic matching of Ab staining intensity using three HER2 Abs produced by different manufacturers. The quality of HER2 Ab was also validated using tissues of breast cancer patients, demonstrating that our system is an efficient and powerful tool for the standardization and quality assurance of IHC. PMID:28378835

  18. Functional maintenance of differentiated embryoid bodies in microfluidic systems: a platform for personalized medicine.

    PubMed

    Guven, Sinan; Lindsey, Jennifer S; Poudel, Ishwari; Chinthala, Sireesha; Nickerson, Michael D; Gerami-Naini, Behzad; Gurkan, Umut A; Anchan, Raymond M; Demirci, Utkan

    2015-03-01

    Hormone replacement therapies have become important for treating diseases such as premature ovarian failure or menopausal complications. The clinical use of bioidentical hormones might significantly reduce some of the potential risks reportedly associated with the use of synthetic hormones. In the present study, we demonstrate the utility and advantage of a microfluidic chip culture system to enhance the development of personalized, on-demand, treatment modules using embryoid bodies (EBs). Functional EBs cultured on microfluidic chips represent a platform for personalized, patient-specific treatment cassettes that can be cryopreserved until required for treatment. We assessed the viability, differentiation, and functionality of EBs cultured and cryopreserved in this system. During extended microfluidic culture, estradiol, progesterone, testosterone, and anti-müllerian hormone levels were measured, and the expression of differentiated steroidogenic cells was confirmed by immunocytochemistry assay for the ovarian tissue markers anti-müllerian hormone receptor type II, follicle-stimulating hormone receptor, and inhibin β-A and the estrogen biosynthesis enzyme aromatase. Our studies showed that under microfluidic conditions, differentiated steroidogenic EBs continued to secrete estradiol and progesterone at physiologically relevant concentrations (30-120 pg/ml and 150-450 pg/ml, respectively) for up to 21 days. Collectively, we have demonstrated for the first time the feasibility of using a microfluidic chip system with continuous flow for the differentiation and extended culture of functional steroidogenic stem cell-derived EBs, the differentiation of EBs into cells expressing ovarian antigens in a microfluidic system, and the ability to cryopreserve this system with restoration of growth and functionality on thawing. These results present a platform for the development of a new therapeutic system for personalized medicine. ©AlphaMed Press.

  19. Piezo-microfluidic transport system for multi-targets biochip detections

    NASA Astrophysics Data System (ADS)

    Li, Chia-Chin; Wang, Pei-Wen; Lee, Chih-Kung

    2016-03-01

    Detecting minute trace of interferon-gamma and various bio-markers by using a single biochip was adopted as a platform to examine the technology advancements presented. As bio-detection faces the restriction that only very small quantity of specimen is available, ways to make the best use of the sample available are a must. Since samples concentration will affect the binding rate of an immunoassay, the testing order will become an influencing factor if multiple biomarkers testing situation are needed by using only a single trace of sample. More specifically, if we test disease A first and then detect disease B using the sample just been measured by testing disease A, we most likely will get different results if we reverse the testing order. With an attempt to examine and maybe resolve the issues mentioned above, a micro-fluid control system was developed. The design requirements not only ask for microfluidic control but also demand the system developed has the potential to be integrated within the biochip once its performance is verified. A piezo-vibrating system that can generate traveling waves for microfluidic control was chosen due to its versatility and large force to volume ratio. A simulation software COMSOL was adopted first to predict the microfluidic behavior of the two-mode excited piezo-microfluidic transport system. Secondly, fluorescent particles was used to analyze the microfluidic behavior of system fabricated based on the simulation. Finally, Electrochemistry Impedance Spectroscopy (EIS) was implemented to verify the performance and extendibility of this newly developed system for multi-target detections.

  20. Hepatic arterial perfusion scintigraphy with Tc-99m-MAA: use of a totally implanted drug delivery system

    SciTech Connect

    Ziessman, H.A.; Thrall, J.H.; Yang, P.J.; Walker, S.C.; Cozzi, E.A.; Niederhuber, J.E.; Gyves, J.W.; Ensminger, W.D.; Tuscan, M.C.

    1984-07-01

    Tc-99m-MAA hepatic arterial perfusion scintigraphy (HAPS) using a totally implanted drug delivery system was employed for hepatic arterial chemotherapy in 147 patients (335 studies). Complete perfusion of the involved liver was seen in 88% of patients initially and remained good on follow-up. A significant decrease in hepatic and/or extrahepatic perfusion associated with a hot spot at the tip of the catheter indicated hepatic arterial thrombosis. Extrahepatic perfusion was seen in 14% of cases, usually in the distribution of the stomach, small bowel, and spleen. Significant symptoms of drug toxicity were seen in 70% of patients with extrahepatic perfusion, compared to 19% of those without it.

  1. 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

  2. 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.

  3. Integration of microelectronic chips in microfluidic systems on printed circuit board

    NASA Astrophysics Data System (ADS)

    Burdallo, I.; Jimenez-Jorquera, C.; Fernández-Sánchez, C.; Baldi, A.

    2012-10-01

    A new scheme for the integration of small semiconductor transducer chips with microfluidic structures on printed circuit board (PCB) is presented. The proposed approach is based on a packaging technique that yields a large and flat area with small and shallow (˜44 µm deep) openings over the chips. The photocurable encapsulant material used, based on a diacrylate bisphenol A polymer, enables irreversible bonding of polydimethylsiloxane microfluidic structures at moderate temperatures (80 °C). This integration scheme enables the insertion of transducer chips in microfluidic systems with a lower added volume than previous schemes. Leakage tests have shown that the bonded structures withstand more than 360 kPa of pressure. A prototype microfluidic system with two detection chips, including one inter-digitated electrode (IDE) chip for conductivity and one ion selective field effect transistor (ISFET) chip for pH, has been implemented and characterized. Good electrical insulation of the chip contacts and silicon edge surfaces from the solution in the microchannels has been achieved. This integration procedure opens the door to the low-cost fabrication of complex analytical microsystems that combine the extraordinary potential of both the microfluidics and silicon microtechnology fields.

  4. Acousto-plasmofluidics: Acoustic modulation of surface plasmon resonance in microfluidic systems

    NASA Astrophysics Data System (ADS)

    Ahmed, Daniel; Peng, Xiaolei; Ozcelik, Adem; Zheng, Yuebing; Huang, Tony Jun

    2015-09-01

    We acoustically modulated the localized surface plasmon resonances (LSPRs) of metal nanostructures integrated within microfluidic systems. An acoustically driven micromixing device based on bubble microstreaming quickly and homogeneously mixes multiple laminar flows of different refractive indices. The altered refractive index of the mixed fluids enables rapid modulation of the LSPRs of gold nanodisk arrays embedded within the microfluidic channel. The device features fast response for dynamic operation, and the refractive index within the channel is tailorable. With these unique features, our "acousto-plasmofluidic" device can be useful in applications such as optical switches, modulators, filters, biosensors, and lab-on-a-chip systems.

  5. 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.

  6. Microfluidic devices, systems, and methods for quantifying particles using centrifugal force

    DOEpatents

    Schaff, Ulrich Y.; Sommer, Gregory J.; Singh, Anup K.

    2015-11-17

    Embodiments of the present invention are directed toward microfluidic systems, apparatus, and methods for measuring a quantity of cells in a fluid. Examples include a differential white blood cell measurement using a centrifugal microfluidic system. A method may include introducing a fluid sample containing a quantity of cells into a microfluidic channel defined in part by a substrate. The quantity of cells may be transported toward a detection region defined in part by the substrate, wherein the detection region contains a density media, and wherein the density media has a density lower than a density of the cells and higher than a density of the fluid sample. The substrate may be spun such that at least a portion of the quantity of cells are transported through the density media. Signals may be detected from label moieties affixed to the cells.

  7. 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.

  8. Biomedical microdevices synthesis of iron oxide nanoparticles using a microfluidic system.

    PubMed

    Lee, Wen-Bin; Weng, Chen-Hsun; Cheng, Fong-Yu; Yeh, Chen-Sheng; Lei, Huan-Yao; Lee, Gwo-Bin

    2009-02-01

    The preparation of nanoparticles is essential in the application of many nanotechnologies and various preparation methods have been explored in the previous decades. Among them, iron oxide nanoparticles have been widely investigated in applications ranging from bio-imaging to bio-sensing due to their unique magnetic properties. Recently, microfluidic systems have been utilized for synthesis of nanoparticles, which have the advantages of automation, well-controlled reactions, and a high particle uniformity. In this study, a new microfluidic system capable of mixing, transporting and reacting was developed for the synthesis of iron oxide nanoparticles. It allowed for a rapid and efficient approach to accelerate and automate the synthesis of the iron oxide nanoparticles as compared with traditional methods. The microfluidic system uses micro-electro-mechanical-system technologies to integrate a new double-loop micromixer, two micropumps, and a microvalve on a single chip. When compared with large-scale synthesis systems with commonly-observed particle aggregation issues, successful synthesis of dispersed and uniform iron oxide nanoparticles has been observed within a shorter period of time (15 min). It was found that the size distribution of these iron oxide nanoparticles is superior to that of the large-scale systems without requiring any extra additives or heating. The size distribution had a variation of 16%. This is much lower than a comparable large-scale system (34%). The development of this microfluidic system is promising for the synthesis of nanoparticles for many future biomedical applications.

  9. Real-time optical pH measurement in a standard microfluidic cell culture system.

    PubMed

    Magnusson, Einar B; Halldorsson, Skarphedinn; Fleming, Ronan M T; Leosson, Kristjan

    2013-01-01

    The rapid growth of microfluidic cell culturing in biological and biomedical research and industry calls for fast, non-invasive and reliable methods of evaluating conditions such as pH inside a microfluidic system. We show that by careful calibration it is possible to measure pH within microfluidic chambers with high accuracy and precision, using a direct single-pass measurement of light absorption in a commercially available phenol-red-containing cell culture medium. The measurement is carried out using a standard laboratory microscope and, contrary to previously reported methods, requires no modification of the microfluidic device design. We demonstrate the validity of this method by measuring absorption of light transmitted through 30-micrometer thick microfluidic chambers, using an inverted microscope fitted with a scientific-grade digital camera and two bandpass filters. In the pH range of 7-8, our measurements have a standard deviation and absolute error below 0.05 for a measurement volume smaller than 4 nL.

  10. [Method for automated extraction and purification of nucleic acids and its implementation in microfluidic system].

    PubMed

    Mamaev, D D; Khodakov, D A; Dement'eva, E I; Filatov, I V; Iurasov, D A; Cherepanov, A I; Vasiliskov, V A; Smoldovskaia, O V; Zimenkov, D V; Griadunov, D A; Mikhaĭlovich, V M; Zasedatelev, A S

    2011-01-01

    A method and a microfluidic device for automated extraction and purification of nucleic acids from biological samples have been developed. The method involves disruption of bacterial cells and/or viral particles by combining enzymatic and chemical lysis procedures followed by solid-phase sorbent extraction and purification of nucleic acids. The procedure is carried out in an automated mode in a microfluidic module isolated from the outside environment, which minimizes contact of the researcher with potentially infectious samples and, consequently, decreases the risk of laboratory-acquired infections. The module includes reservoirs with lyophilized components for lysis and washing buffers; a microcolumn with a solid-phase sorbent; reservoirs containing water, ethanol, and water-ethanol buffer solutions for dissolving freeze-dried buffer components, rinsing the microcolumn, and eluting of nucleic acids; and microchannels and valves needed for directing fluids inside the module. The microfluidic module is placed into the control unit that delivers pressure, heats, mixes reagents, and flows solutions within the microfluidic module. The microfluidic system performs extraction and purification of nucleic acids with high efficiency in 40 min, and nucleic acids extracted can be directly used in PCR reaction and microarray assays.

  11. Development of microfluidic system and optical tweezers for electrophysiological investigations of an individual cell

    NASA Astrophysics Data System (ADS)

    Alrifaiy, A.; Bitaraf, N.; Lindahl, O.; Ramser, K.

    2010-08-01

    We present a new approach of combining Lab-on-a-chip technologies with optical manipulation technique for accurate investigations in the field of cell biology. A general concept was to develop and combine different methods to perform advanced electrophysiological investigations of an individual living cell under optimal control of the surrounding environment. The conventional patch clamp technique was customized by modifying the open system with a gas-tight multifunctional microfluidics system and optical trapping technique (optical tweezers). The system offers possibilities to measure the electrical signaling and activity of the neuron under optimum conditions of hypoxia and anoxia while the oxygenation state is controlled optically by means of a spectroscopic technique. A cellbased microfluidics system with an integrated patch clamp pipette was developed successfully. Selectively, an individual neuron is manipulated within the microchannels of the microfluidic system under a sufficient control of the environment. Experiments were performed to manipulate single yeast cell and red blood cell (RBC) optically through the microfluidics system toward an integrated patch clamp pipette. An absorption spectrum of a single RCB was recorded which showed that laser light did not impinge on the spectroscopic spectrum of light. This is promising for further development of a complete lab-on-a-chip system for patch clamp measurements.

  12. Zeta potential determination by streaming current modelization and measurement in electrophoretic microfluidic systems.

    PubMed

    Renaud, Louis; Kleimann, Pascal; Morin, Pierre

    2004-01-01

    Electrophoresis in capillary and microfluidic systems, used in analytical chemistry to separate charged species, are quite sensitive to surface phenomena in terms of separation performances. In order to improve theses performances, new surface functionalization techniques are required. There is a need for methods to provide fast and accurate quantification about surface charges at liquid/solid interfaces. We present a fast, simple, and low-cost technique for the measurement of the zeta-potential, via the modelization and the measurement of streaming currents. Due to the small channel cross section in microfluidic devices, the streaming current modelization is easier than the streaming potential measurement. The modelization combines microfluidic simulations based on the Navier-Stokes equation and charge repartition simulations based on the Poisson-Boltzmann equation. This method has been validated with square and circular cross section shape fused-silica capillaries and can be easily transposed to any lab-on-chip microsystems.

  13. 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.

  14. Dependence of quantitative accuracy of CT perfusion imaging on system parameters

    NASA Astrophysics Data System (ADS)

    Li, Ke; Chen, Guang-Hong

    2017-03-01

    Deconvolution is a popular method to calculate parametric perfusion parameters from four dimensional CT perfusion (CTP) source images. During the deconvolution process, the four dimensional space is squeezed into three-dimensional space by removing the temporal dimension, and a prior knowledge is often used to suppress noise associated with the process. These additional complexities confound the understanding about deconvolution-based CTP imaging system and how its quantitative accuracy depends on parameters and sub-operations involved in the image formation process. Meanwhile, there has been a strong clinical need in answering this question, as physicians often rely heavily on the quantitative values of perfusion parameters to make diagnostic decisions, particularly during an emergent clinical situation (e.g. diagnosis of acute ischemic stroke). The purpose of this work was to develop a theoretical framework that quantitatively relates the quantification accuracy of parametric perfusion parameters with CTP acquisition and post-processing parameters. This goal was achieved with the help of a cascaded systems analysis for deconvolution-based CTP imaging systems. Based on the cascaded systems analysis, the quantitative relationship between regularization strength, source image noise, arterial input function, and the quantification accuracy of perfusion parameters was established. The theory could potentially be used to guide developments of CTP imaging technology for better quantification accuracy and lower radiation dose.

  15. Rapid separation of bacteriorhodopsin using a laminar-flow extraction system in a microfluidic device

    PubMed Central

    Huh, Yun Suk; Jeong, Chang-Moon; Chang, Ho Nam; Lee, Sang Yup; Hong, Won Hi; Park, Tae Jung

    2010-01-01

    A protein separation technology using the microfluidic device was developed for the more rapid and effective analysis of target protein. This microfluidic separation system was carried out using the aqueous two-phase system (ATPS) and the ionic liquid two-phase system (ILTPS) for purification method of the protein sample, and the three-flow desalting system was used for the removal of salts from the sucrose-rich sample. Partitioning of the protein sample was observed in ATPS or ILTPS with the various pHs. The microdialysis system was applied to remove small molecules, such as sucrose and salts in the microfluidic channel with the different flow rates of buffer phase. A complex purification method, which combines microdialysis and ATPS or ILTPS, was carried out for the effective purification of bacteriorhodopsin (BR) from the purple membrane of Halobacterium salinarium, which was then analyzed by sodium dodecyl sulfatepolyacrylamide gel electrophoresis and matrix-assisted laser desorption∕ionization time-of-flight. Furthermore, we were able to make a stable three-phase flow controlling the flow rate in the microfluidic channel. Our complex purification methods were successful in purifying and recovering the BR to its required value. PMID:20644672

  16. Rollable Microfluidic Systems with Microscale Bending Radius and Tuning of Device Function with Reconfigurable 3D Channel Geometry.

    PubMed

    Kim, Jihye; You, Jae Bem; Nam, Sung Min; Seo, Sumin; Im, Sung Gap; Lee, Wonhee

    2017-03-29

    Flexible microfluidic system is an essential component of wearable biosensors to handle body fluids. A parylene-based, thin-film microfluidic system is developed to achieve flexible microfluidics with microscale bending radius. A new molding and bonding technique is developed for parylene microchannel fabrication. Bonding with nanoadhesive layers deposited by initiated chemical vapor deposition (iCVD) enables the construction of microfluidic channels with short fabrication time and high bonding strength. The high mechanical strength of parylene allows less channel deformation from the internal pressure for the thin-film parylene channel than bulk PDMS channel. At the same time, negligible channel sagging or collapse is observed during channel bending down to a few hundreds of micrometers due to stress relaxation by prestretch structure. The flexible parylene channels are also developed into a rollable microfluidic system. In a rollable microfluidics format, 2D parylene channels can be rolled around a capillary tubing working as inlets to minimize the device footprint. In addition, we show that creating reconfigurable 3D channel geometry with microscale bending radius can lead to tunable device function: tunable Dean-flow mixer is demonstrated using reconfigurable microscale 3D curved channel. Flexible parylene microfluidics with microscale bending radius is expected to provide an important breakthrough for many fields including wearable biosensors and tunable 3D microfluidics.

  17. Venovenous perfusion-induced systemic hyperthermia: five-day sheep survival studies.

    PubMed

    Ballard-Croft, Cherry; Wang, Dongfang; Rosenstein, Kyle; Wang, Jingkun; Pollock, Robert; Morris, J Ann; Zwischenberger, Joseph B

    2014-11-01

    Since hyperthermia selectively kills lung cancer cells, we developed a venovenous perfusion-induced systemic hyperthermia system for advanced lung cancer therapy. Our objective was to test the safety and accuracy of our venovenous perfusion-induced systemic hyperthermia system in 5-day sheep survival studies, following Good Laboratory Practice standards. Our venovenous perfusion-induced systemic hyperthermia system, which included a double-lumen cannula (Avalon Elite, Rancho Dominguez, Calif), a centrifugal pump (Bio-Pump 560; Medtronic Inc, Minneapolis, Minn), a heat exchanger (BIOtherm; Medtronic Perfusion Systems, Brooklyn Park, Minn), and a heater/cooler (modified Blanketrol IIIl Cincinnati Subzero, Cincinnati, Ohio), was tested in healthy adult sheep (n=5). The perfusion circuit was primed with prewarmed Plasma-Lyte A (Baxter Healthcare Corp, Deerfield, Ill) and de-aired. Calibrated temperature probes were placed in the right and left sides of the nasopharynx, bladder, and blood in/out tubing in the animal. The double-lumen cannula was inserted through the jugular vein into the superior vena cava, with the tip in the inferior vena cava. Therapeutic core temperature (42°C-42.5°C), calculated from the right and left sides of the nasopharynx and bladder temperatures, was achieved in all sheep. Heating time was 21±5 minutes. Therapeutic core temperature was maintained for 120 minutes followed by a cooling phase (35±6 minutes) to reach baseline temperature. All sheep recovered from anesthesia with spontaneous breathing within 4 hours. Arterial, pulmonary, and central venous pressures were stable. Transient increases in heart rate, cardiac output, and blood glucose occurred during hyperthermia but returned to normal range after venovenous perfusion-induced systemic hyperthermia termination. Electrolytes, complete blood counts, and metabolism enzymes were within normal to near normal range throughout the study. No significant venovenous perfusion-induced systemic

  18. High sensitivity automated multiplexed immunoassays using photonic crystal enhanced fluorescence microfluidic system.

    PubMed

    Tan, Yafang; Tang, Tiantian; Xu, Haisheng; Zhu, Chenqi; Cunningham, Brian T

    2015-11-15

    We demonstrate a platform that integrates photonic crystal enhanced fluorescence (PCEF) detection of a surface-based microspot fluorescent assay with a microfluidic cartridge to achieve simultaneous goals of high analytic sensitivity (single digit pg/mL), high selectivity, low sample volume, and assay automation. The PC surface, designed to provide optical resonances for the excitation wavelength and emission wavelength of Cyanines 5 (Cy5), was used to amplify the fluorescence signal intensity measured from a multiplexed biomarker microarray. The assay system is comprised of a plastic microfluidic cartridge for holding the PC and an assay automation system that provides a leak-free fluid interface during introduction of a sequence of fluids under computer control. Through the use of the assay automation system and the PC embedded within the microfluidic cartridge, we demonstrate pg/mL-level limits of detection by performing representative biomarker assays for interleukin 3 (IL3) and Tumor Necrosis Factor (TNF-α). The results are consistent with limits of detection achieved without the use of the microfluidic device with the exception that coefficients of variability from spot-to-spot are substantially lower than those obtained by performing assays with manual manipulation of assay liquids. The system's capabilities are compatible with the goal of diagnostic instruments for point-of-care settings.

  19. An integrated microfluidic system for bovine DNA purification and digital PCR detection.

    PubMed

    Tian, Qingchang; Mu, Ying; Xu, Yanan; Song, Qi; Yu, Bingwen; Ma, Congcong; Jin, Wei; Jin, Qinhan

    2015-12-15

    In this paper, we described an integrated modularized microfluidic system that contained two distinct functional modules, one for nucleic acids (NA) extraction and the other for digital PCR (dPCR), allowing for detecting the bovine DNA in ovine tissue. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. A simple physiologic pulsatile perfusion system for the study of intact vascular tissue.

    PubMed

    Conklin, B S; Surowiec, S M; Lin, P H; Chen, C

    2000-07-01

    Perfusion vascular culture models may provide a useful link between cell culture models and animal culture models by allowing a high level of control over important parameters while maintaining physiologic structure. The purpose of this study was to develop and test a new vascular culture system for pulsatile perfusion culture of intact vascular tissue. The system generates a pulsatile component of flow by means of a cam-driven syringe and a peristaltic pump and compliance chamber. Cams were designed, constructed and tested to simulate canine femoral and common carotid artery flows. The mean pressure was adjusted between 60 and 200 mmHg without significantly affecting flow rate, flow waveform, or the pressure waveform. Porcine common carotid artery segments were cultured in this pulsatile perfusion system. The viability of vascular segments was tested after various culture times with a functional assay that demonstrated both smooth muscle cell and endothelial cell response to vasomotor challenge.

  1. An active bubble trap and debubbler for microfluidic systems.

    PubMed

    Skelley, Alison M; Voldman, Joel

    2008-10-01

    We present a novel, fully integrated microfluidic bubble trap and debubbler. The 2-layer structure, based on a PDMS valve design, utilizes a featured membrane to stop bubble progression through the device. A pneumatic chamber directly above the trap is evacuated, and the bubble is pulled out through the gas-permeable PDMS membrane. Normal device operation, including continuous flow at atmospheric pressure, is maintained during the entire trapping and debubbling process. We present a range of trap sizes, from 2 to 10 mm diameter, and can trap and remove bubbles up to 25 microL in under 3 h.

  2. Complex Approach to Xenobiotics Hepatotoxicity Testing using a Microfluidic System.

    PubMed

    Alexandrova, A V; Pul'kova, N V; Sakharov, D A

    2016-05-01

    We analyzed hepatotoxicity of three drugs: acetaminophen, metformin, and isoniazid. Spheroids of differentiated HepaRG cells cultured under microfluidic conditions were used as the model. Acute toxicity of substances was assessed by analyzing cell viability, while lactate concentration in the culture medium was used as the potential marker for evaluation of chronic exposure and non-lethal side effects of xenobiotics. The results were compared with mitochondrial activity and DNA fragmentation data. The efficiency and possibility of applying the integrated approach for assessment of drug hepatotoxicity are discussed.

  3. Modified harvest system for enhancing Factor VIII yield in alternating tangential flow perfusion culture.

    PubMed

    Kim, Seung-Chul; An, Sora; Kim, Hyun-Ki; Park, Beom-Soo; Na, Kyu-Heum; Kim, Byung-Gee

    2016-05-01

    This study describes the development and experimental verification of a modified harvest system to enhance Factor VIII (FVIII) yield in an alternating tangential flow (ATF) perfusion culture. The main innovation of the modified harvest system is the use of check and pinch valves, eliminating the need of a peristaltic pump for harvest. The system was applied to perfusion cultures of Chinese hamster ovary cells, which co-express both recombinant human FVIII (rhFVIII) and von Willebrand factor (vWF). The modified harvest system showed comparable cell growth with the conventional harvest system using a peristaltic pump. The perfusion rate was successfully controlled using the system. In addition, the modified harvest system achieved an approximately 13.6-fold increase in the final concentration yield of FVIII activity and a 1.47-fold increase in the production yield of FVIII activity compared with a peristaltic pump. Enhancement of the yield of FVIII activity resulted from the reduction of FVIII antigen ( Ag) retention. As a result of transmembrane pressure (TMP) measurement, the reduction of the retained Ag was due to the increased TMP, which was caused by the characteristic function of a check valve, compared with a peristaltic harvest system. The modified harvest system developed in this study could be useful to enhance the production yield of other recombinant proteins in ATF perfusion culture. Copyright © 2015. Published by Elsevier B.V.

  4. High Sensitivity Automated Multiplexed Immunoassays Using Photonic Crystal Enhanced Fluorescence Microfluidic System

    PubMed Central

    Tan, Yafang; Tang, Tiantian; Xu, Haisheng; Zhu, Chenqi; Cunningham, Brian T.

    2015-01-01

    We demonstrate a platform that integrates photonic crystal enhanced fluorescence (PCEF) detection of a surface-based microspot fluorescent assay with a microfluidic cartridge to achieve simultaneous goals of high analytic sensitivity (single digit pg/mL), high selectivity, low sample volume, and assay automation. The PC surface, designed to provide optical resonances for the excitation wavelength and emission wavelength of Cyanines 5 (Cy5), was used to amplify the fluorescence signal intensity measured from a multiplexed biomarker microarray. The assay system is comprised of a plastic microfluidic cartridge for holding the PC and an assay automation system that provides a leak-free fluid interface during introduction of a sequence of fluids under computer control. Through the use of the assay automation system and the PC embedded within the microfluidic cartridge, we demonstrate pg/mL-level limits of detection by performing representative biomarker assays for interleukin 3 (IL3) and Tumor Necrosis Factor (TNF-α). The results are consistent with limits of detection achieved without the use of the microfluidic device with the exception that coefficients of variability from spot-to-spot are substantially lower than those obtained by performing assays with manual manipulation of assay liquids. The system’s capabilities are compatible with the goal of diagnostic instruments for point-of-care settings. PMID:26043313

  5. Integration of microfluidics/electrochemical system for trace metal analysis by stripping voltammetry

    NASA Astrophysics Data System (ADS)

    Lin, Yuehe; Zhao, Rui; Thrall, Karla D.; Timchalk, C. A.; Bennett, Wendy D.; Matson, Dean W.

    1999-08-01

    Microanalytical systems based on a microfluidics/electrochemical detection scheme were developed. Individual modules, such as microfabricated piezoelectrically actuated pumps and a microelectrochemical cell were integrated onto portable platforms. This allows rapid change-out and repair of individual components by incorporating `plug and play' concepts now standard in PC's. Two different integration schemes were used for construction of the microanalytical systems based on microfluidics/electrochemical detection. In first scheme, all individual modules were integrated in the surface of the standard microfluidic platform based on a plug-and-play design. Microelectrochemical flow cell which integrated three electrodes based on a wall-jet design was fabricated on polymer substrate. The microelectrochemical flow cell was then plugged directly into the microfluidic platform. Another integration scheme was based on a multilayer lamination method utilizing stacking modules with different functionality to achieve a compact microanalytical device. Application of the microanalytical system for detection of lead in river water and saliva samples using stripping voltammetry is described.

  6. A microfluidic system with integrated molecular imprinting polymer films for surface plasmon resonance detection

    NASA Astrophysics Data System (ADS)

    Huang, Shih-Chiang; Lee, Gwo-Bin; Chien, Fan-Ching; Chen, Shean-Jen; Chen, Wen-Janq; Yang, Ming-Chang

    2006-07-01

    This paper presents a novel microfluidic system with integrated molecular imprinting polymer (MIP) films designed for surface plasmon resonance (SPR) biosensing of multiple nanoscale biomolecules. The innovative microfluidic chip uses pneumatic microvalves and micropumps to transport a precise amount of the biosample through multiple microchannels to sensing regions containing the locally spin-coated MIP films. The signals of SPR biosensing are basically proportional to the number of molecules adsorbed on the MIP films. Hence, a precise control of flow rates inside microchannels is important to determine the adsorption amount of the molecules in the SPR/MIP chips. The integration of micropumps and microvalves can automate the sample introduction process and precisely control the amount of the sample injection to the microfluidic system. The proposed biochip enables the label-free biosensing of biomolecules in an automatic format, and provides a highly sensitive, highly specific and high-throughput detection performance. Three samples, i.e. progesterone, cholesterol and testosterone, are successfully detected using the developed system. The experimental results show that the proposed SPR/MIP microfluidic chip provides a comparable sensitivity to that of large-scale SPR techniques, but with reduced sample consumption and an automatic format. As such, the developed biochip has significant potential for a wide variety of nanoscale biosensing applications. The preliminary results of the current paper were presented at Transducers 2005, Seoul, Korea, 5-9 June 2005.

  7. 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.

  8. 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.

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

    PubMed Central

    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. PMID:24404071

  10. Detecting physiological systems with laser speckle perfusion imaging of the renal cortex.

    PubMed

    Scully, Christopher G; Mitrou, Nicholas; Braam, Branko; Cupples, William A; Chon, Ki H

    2013-06-01

    Laser speckle perfusion imaging (LSPI) has become an increasingly popular technique for monitoring vascular perfusion over a tissue surface. However, few studies have utilized the full range of spatial and temporal information generated by LSPI to monitor spatial properties of physiologically relevant dynamics. In this study, we extend the use of LSPI to analyze renal perfusion dynamics over a spatial surface of ~5 × 7 mm of renal cortex. We identify frequencies related to five physiological systems that induce temporal changes in renal vascular perfusion (cardiac flow pulse, respiratory-induced oscillations, baroreflex components, the myogenic response, and tubuloglomerular feedback) across the imaged surface and compare the results with those obtained from renal blood flow measurements. We find that dynamics supplied from global sources (cardiac, respiration, and baroreflex) present with the same frequency at all locations across the imaged surface, but the local renal autoregulation dynamics can be heterogeneous in their distribution across the surface. Moreover, transfer function analysis with forced blood pressure as the input yields the same information with laser speckle imaging or renal blood flow as the output during control, intrarenal infusion of N(ω)-nitro-L-arginine methyl ester to enhance renal autoregulation, and intrarenal infusion of the rho-kinase inhibitor Y-27632 to inhibit vasomotion. We conclude that LSPI measurements can be used to analyze local as well as global renal perfusion dynamics and to study the properties of physiological systems across the renal cortex.

  11. Laminated microfluidic system for small sample protein analysis

    PubMed Central

    Saedinia, Sara; Nastiuk, Kent L.; Krolewski, John J.; Li, G. P.; Bachman, Mark

    2014-01-01

    We describe a technology based on lamination that allows for the production of highly integrated 3D devices suitable for performing a wide variety of microfluidic assays. This approach uses a suite of microfluidic coupons (“microfloupons”) that are intended to be stacked as needed to produce an assay of interest. Microfloupons may be manufactured in paper, plastic, gels, or other materials, in advance, by different manufacturers, then assembled by the assay designer as needed. To demonstrate this approach, we designed, assembled, and characterized a microfloupon device that performs sodium-dodecyl-sulfate polyacrylamide gel electrophoresis on a small sample of protein. This device allowed for the manipulation and transport of small amounts of protein sample, tight injection into a thin polyacrylamide gel, electrophoretic separation of the proteins into bands, and subsequent removal of the gel from the device for imaging and further analysis. The microfloupons are rugged enough to handle and can be easily aligned and laminated, allowing for a variety of different assays to be designed and configured by selecting appropriate microfloupons. This approach provides a convenient way to perform assays that have multiple steps, relieving the need to design highly sophisticated devices that incorporate all functions in a single unit, while still achieving the benefits of small sample size, automation, and high speed operation. PMID:24753728

  12. Uncoupling the systemic circulation and the Ex Vivo circuit during experimental isolated liver perfusion.

    PubMed

    Lhuillier, Franck; Pouyet, Michel; Méchet, Isabelle; Liotard, Dominique; Merle, Eric; Delafosse, Bertrand; Goudable, Joelle; Vianey-Saban, Christine; Viale, Jean-Paul

    2006-01-01

    Performing an ex vivo liver perfusion as a transient liver support requires perfusing the liver with a flow of 1 ml/min per kg of liver, which could reach 25% of the cardiac output when a human liver is used. This high flow could be detrimental in patients with acute liver failure. Therefore, in an ischemic-induced liver failure pig model, we developed a circuit allowing low flows going out of and into the systemic circulation, whereas the flow going through the ex vivo liver is maintained at a high value. This was obtained by uncoupling the ex vivo circuit from the systemic circulation. Ex vivo liver perfusion was performed in a closed circuit with a flow averaging 1 ml/min per kg of ex vivo liver (700 to 800 ml/min, according to the weight of the livers we used). It was linked to the systemic circulation with input and output flows equal to that used during hemodialysis (200 ml/min). Compared with previously reported direct circuits, this perfusion system was well tolerated from a circulatory point of view. After the induction of ischemic liver failure, the ex vivo liver perfusion led to an increase in urea, branched amino acids to aromatic amino acid ratio, and fractional clearance of indocyanine green and galactose and to a decrease in ammonia and lactic acid. This system allowed the ex vivo liver to keep its clearing properties despite a low extracorporeal flow. It represents an extracorporeal circuit that could be used in place of the direct extracorporeal high-flow liver perfusion.

  13. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems

    PubMed Central

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems. PMID:26823292

  14. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems

    NASA Astrophysics Data System (ADS)

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems.

  15. Characterization of electrode alignment for optimal droplet charging and actuation in droplet-based microfluidic system.

    PubMed

    Ahn, Myung Mo; Im, Do Jin; Yoo, Byeong Sun; Kang, In Seok

    2015-09-01

    The actuation method using electric force as a driving force is utilized widely in droplet-based microfluidic systems. In this work, the effects of charging electrode alignment on direct charging of a droplet on electrified electrodes and a subsequent electrophoretic control of the droplet are investigated. The charging characteristics of a droplet according to different electrode alignments are quantitatively examined through experiments and systematic numerical simulations with varying distances and angles between the two electrodes. The droplet charge acquired from the electrified electrode is directly proportional to the distance and barely affected by the angle between the two electrodes. This implies that the primary consideration of electrode alignment in microfluidic devices is the distance between electrodes and the insignificant effect of angle provides a great degree of freedom in designing such devices. Not only the droplet charge acquired from the electrode but also the force exerted on the droplet is analyzed. Finally, the implications and design guidance for microfluidic systems are discussed with an electrophoresis of a charged droplet method-based digital microfluidic device. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems.

    PubMed

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-29

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems.

  17. A Serial Sample Loading System: Interfacing Multi-well plates with Microfluidic Devices

    PubMed Central

    Rane, Tushar D.; Zec, Helena; Wang, Jeff Tza-Huei

    2013-01-01

    There is an increasing demand for novel high-throughput screening (HTS) technologies in the pharmaceutical and biotechnological industries. The robotic sample handling techniques currently used in these industries, although fast, are still limited to operating in multi-well plates with the sample volumes per reaction in the microliter regime. Digital microfluidics offers an alternative for reduction in sample volume consumption for HTS but lacks a reliable technique for transporting large number of samples to the microfluidic device. In this report, we develop a technique for serial delivery of sample arrays to a microfluidic device from multi-well plates, through a single sample inlet. Under this approach, a serial array of sample plugs, separated by an immiscible carrier fluid, is loaded into a capillary and delivered to a microfluidic device. Similar approaches have been attempted in the past, however, either with a slower sample loading device like syringe pump or vacuum based sample loading with limited driving pressure. We demonstrated the application of our positive pressure based ‘Serial Sample Loading’ (SSL) system to load a series of sample plugs into a capillary. The adaptability of the SSL system to generate sample plugs with a variety of volumes in a predictable manner was also demonstrated. PMID:22885789

  18. A serial sample loading system: interfacing multiwell plates with microfluidic devices.

    PubMed

    Rane, Tushar D; Zec, Helena C; Wang, Tza-Huei

    2012-10-01

    There is an increasing demand for novel high-throughput screening (HTS) technologies in the pharmaceutical and biotechnological industries. The robotic sample-handling techniques currently used in these industries, although fast, are still limited to operating in multiwell plates with the sample volumes per reaction in the microliter regime. Digital microfluidics offers an alternative for reduction in sample volume consumption for HTS but lacks a reliable technique for transporting a large number of samples to the microfluidic device. In this report, we develop a technique for serial delivery of sample arrays to a microfluidic device from multiwell plates, through a single sample inlet. Under this approach, a serial array of sample plugs, separated by an immiscible carrier fluid, is loaded into a capillary and delivered to a microfluidic device. Similar approaches have been attempted in the past, however, either with a slower sample loading device such as a syringe pump or vacuum-based sample loading with limited driving pressure. We demonstrated the application of our positive-pressure-based serial sample loading (SSL) system to load a series of sample plugs into a capillary. The adaptability of the SSL system to generate sample plugs with a variety of volumes in a predictable manner was also demonstrated.

  19. A Novel Impedimetric Microfluidic Analysis System for Transgenic Protein Cry1Ab Detection

    PubMed Central

    Jin, Shunru; Ye, Zunzhong; Wang, Yixian; Ying, Yibin

    2017-01-01

    Impedimetric analysis method is an important tool for food safety detection. In this work, a novel impedimetric microfluidic analysis system consisted of a printed gold electrode chip and a microfluidic flow cell was developed for sensitive and selective detection of transgenic protein Cry1Ab. Anti-Cry1Ab aptamer coated magnetic beads were used to recognize transgenic protein Cry1Ab and form Cry1Ab-aptamer modified magnetic beads. After separation, the obtained Cry1Ab-aptamer modified magnetic beads were dissolved in 0.01 M mannitol and followed by injection into the microfluidic flow cell for impedimetric measurement. At the frequency of 358.3 Hz, the impedance signal shows a good linearity with the concentrations of Cry1Ab protein at a range from 0 to 0.2 nM, and the detection limit is 0.015 nM. The results demonstrate that the impedimetric microfluidic analysis system provides an alternative way to enable sensitive, rapid and specific detection of transgenic protein Cry1Ab. PMID:28251986

  20. An In Vitro Perfusion System to Enhance Outflow Studies in Mouse Eyes

    PubMed Central

    Kizhatil, Krishnakumar; Chlebowski, Arthur; Tolman, Nicholas G.; Freeburg, Nelson F.; Ryan, Margaret M.; Shaw, Nicholas N.; Kokini, Alexander D. M.; Marchant, Jeffrey K.; John, Simon W. M.

    2016-01-01

    Purpose The molecular mechanisms controlling aqueous humor (AQH) outflow and IOP need much further definition. The mouse is a powerful system for characterizing the mechanistic basis of AQH outflow. To enhance outflow studies in mice, we developed a perfusion system that is based on human anterior chamber perfusion culture systems. Our mouse system permits previously impractical experiments. Methods We engineered a computer-controlled, pump-based perfusion system with a platform for mounting whole dissected mouse eyes (minus lens and iris, ∼45% of drainage tissue is perfused). We tested the system's ability to monitor outflow and tested the effects of the outflow-elevating drug, Y27632, a rho-associated protein kinase (ROCK) inhibitor. Finally, we tested the system's ability to detect genetically determined decreases in outflow by determining if deficiency of the candidate genes Nos3 and Cav1 alter outflow. Results Using our system, the outflow facility (C) of C57BL/6J mouse eyes was found to range between 7.7 and 10.4 nl/minutes/mm Hg (corrected for whole eye). Our system readily detected a 74.4% Y27632-induced increase in C. The NOS3 inhibitor L-NG-nitroarginine methyl ester (L-NAME) and a Nos3 null mutation reduced C by 28.3% and 35.8%, respectively. Similarly, in Cav1 null eyes C was reduced by 47.8%. Conclusions We engineered a unique perfusion system that can accurately measure changes in C. We then used the system to show that NOS3 and CAV1 are key components of mechanism(s) controlling outflow. PMID:27701632

  1. Multi-layer plastic/glass microfluidic systems containing electrical and mechanical functionality.

    PubMed

    Han, Arum; Wang, Olivia; Graff, Mason; Mohanty, Swomitra K; Edwards, Thayne L; Han, Ki-Ho; Bruno Frazier, A

    2003-08-01

    This paper describes an approach for fabricating multi-layer microfluidic systems from a combination of glass and plastic materials. Methods and characterization results for the microfabrication technologies underlying the process flow are presented. The approach is used to fabricate and characterize multi-layer plastic/glass microfluidic systems containing electrical and mechanical functionality. Hot embossing, heat staking of plastics, injection molding, microstenciling of electrodes, and stereolithography were combined with conventional MEMS fabrication techniques to realize the multi-layer systems. The approach enabled the integration of multiple plastic/glass materials into a single monolithic system, provided a solution for the integration of electrical functionality throughout the system, provided a mechanism for the inclusion of microactuators such as micropumps/valves, and provided an interconnect technology for interfacing fluids and electrical components between the micro system and the macro world.

  2. Rewarming preservation by organ perfusion system for donation after cardiac death liver grafts in pigs.

    PubMed

    Matsuno, N; Obara, H; Watanabe, R; Iwata, S; Kono, S; Fujiyama, M; Hirano, T; Kanazawa, H; Enosawa, S

    2014-05-01

    Use of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. However, this requires the development of novel preservation methods to recover the organ from changes due to warm ischemia time (WIT). Porcine livers were perfused with a newly developed machine perfusion (MP) system. The livers were perfused with modified University of Wisconsin solution (UW) - gluconate. All grafts were procured after acute hemorrhagic shock with the ventilator off. For group 1 (n = 6), grafts were procured after WIT of 60 minutes and preserved by hypothermic MP (HMP) for 3 hours. For group 2 (n = 5), grafts were preserved with 2 hours of simple cold storage (SCS) and HMP for 2 hours. For group 3 (n = 6), grafts were preserved with 2 hours of SCS and rewarming up to 25°C by MP for 2 hours (RMP). The preserved liver grafts were transplanted orthotopically. The alanine aminotransferase level in perfusate in RMP during perfusion preservation was maintained at less than that of HMP. The levels of aspartate aminotransferase and lactate dehydrogenase in the 2 hours after reperfusion were significantly lower in group 3. Histologically, the necrosis of hepatocytes was less severe in group 3. The survival rate in group 3 was 2/4, but 0/4 in the other group. RMP is expected to facilitate the recovery of the DCD liver grafts. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. PCB/polymer based micro-fluidic system for NMR spectroscopy for nanoliters sample volume.

    PubMed

    Pasquet, Guillaume; Chateaux, Jean-François; Deman, Anne-Laure; Fenet, Bernard; Morin, Pierre

    2007-01-01

    In this work, we report on the realization of an innovating micro system for NMR spectroscopy on small sample volume (30-100 nL). We propose a micro system based on Printed Circuit Board (PCB) technology for the NMR probe associated to a micro fluidic system made with polymer (COC). The comparison of several samples during the same NMR experiments could provide more precise information. In that context, we have realized a micro-fluidic system with two cavities, each cavity presenting a volume of 37 nl. The fabrication process is described, and first results are reported. The tight sealing of the micro-fluidic system has been demonstrated and preliminary NMR experiment results are presented.

  4. Design modification and optimisation of the perfusion system of a tri-axial bioreactor for tissue engineering.

    PubMed

    Hussein, Husnah; Williams, David J; Liu, Yang

    2015-07-01

    A systematic design of experiments (DOE) approach was used to optimize the perfusion process of a tri-axial bioreactor designed for translational tissue engineering exploiting mechanical stimuli and mechanotransduction. Four controllable design parameters affecting the perfusion process were identified in a cause-effect diagram as potential improvement opportunities. A screening process was used to separate out the factors that have the largest impact from the insignificant ones. DOE was employed to find the settings of the platen design, return tubing configuration and the elevation difference that minimise the load on the pump and variation in the perfusion process and improve the controllability of the perfusion pressures within the prescribed limits. DOE was very effective for gaining increased knowledge of the perfusion process and optimizing the process for improved functionality. It is hypothesized that the optimized perfusion system will result in improved biological performance and consistency.

  5. Single-cell microfluidics: opportunity for bioprocess development.

    PubMed

    Grünberger, Alexander; Wiechert, Wolfgang; Kohlheyer, Dietrich

    2014-10-01

    Cell-to-cell heterogeneity in microbial biotechnological processes caused by biological (intrinsic) and environmental (extrinsic) fluctuations can have a severe impact on productivity. However, as yet little is known about the complex interplay between environmental reactor dynamics and cellular activity. A few years ago, innovative microfluidic systems were introduced facilitating the spatiotemporal analysis of single cells under well-defined environmental conditions allowing so far unachievable insights into population heterogeneity and bioreactor inhomogeneity. Examples of microfabricated systems include microfluidic cavities harbouring micropopulations of several thousand cells down to femtolitre-size structures entrapping individual bacteria. In well-defined perfusion experiments, central questions in biotechnology regarding, for example, growth, productivity, and heterogeneity on the single-cell level have been addressed for the first time. Microfluidics will take its place as a single-cell analytical technique in biotechnological process and strain characterization. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Metabolomics-on-a-chip and predictive systems toxicology in microfluidic bioartificial organs.

    PubMed

    Shintu, Laetitia; Baudoin, Régis; Navratil, Vincent; Prot, Jean-Matthieu; Pontoizeau, Clément; Defernez, Marianne; Blaise, Benjamin J; Domange, Céline; Péry, Alexandre R; Toulhoat, Pierre; Legallais, Cécile; Brochot, Céline; Leclerc, Eric; Dumas, Marc-Emmanuel

    2012-02-21

    The world faces complex challenges for chemical hazard assessment. Microfluidic bioartificial organs enable the spatial and temporal control of cell growth and biochemistry, critical for organ-specific metabolic functions and particularly relevant to testing the metabolic dose-response signatures associated with both pharmaceutical and environmental toxicity. Here we present an approach combining a microfluidic system with (1)H NMR-based metabolomic footprinting, as a high-throughput small-molecule screening approach. We characterized the toxicity of several molecules: ammonia (NH(3)), an environmental pollutant leading to metabolic acidosis and liver and kidney toxicity; dimethylsulfoxide (DMSO), a free radical-scavenging solvent; and N-acetyl-para-aminophenol (APAP, or paracetamol), a hepatotoxic analgesic drug. We report organ-specific NH(3) dose-dependent metabolic responses in several microfluidic bioartificial organs (liver, kidney, and cocultures), as well as predictive (99% accuracy for NH(3) and 94% for APAP) compound-specific signatures. Our integration of microtechnology, cell culture in microfluidic biochips, and metabolic profiling opens the development of so-called "metabolomics-on-a-chip" assays in pharmaceutical and environmental toxicology.

  7. Microvalve Enabled Digital Microfluidic Systems for High Performance Biochemical and Genetic Analysis.

    PubMed

    Jensen, Erik C; Zeng, Yong; Kim, Jungkyu; Mathies, Richard A

    2010-12-01

    Microfluidic devices offer unparalleled capability for digital microfluidic automation of sample processing and complex assay protocols in medical diagnostic and research applications. In our own work, monolithic membrane valves have enabled the creation of two platforms that precisely manipulate discrete, nanoliter-scale volumes of sample. The digital microfluidic Automaton uses two-dimensional microvalve arrays to combinatorially process nanoliter-scale sample volumes. This programmable system enables rapid integration of diverse assay protocols using a universal processing architecture. Microfabricated emulsion generator array (MEGA) devices integrate actively controlled 3-microvalve pumps to enable on-demand generation of uniform droplets for statistical encapsulation of microbeads and cells. A MEGA device containing 96 channels confers the capability of generating up to 3.4 × 10(6) nanoliter-volume droplets per hour for ultrahigh-throughput detection of rare mutations in a vast background of normal genotypes. These novel digital microfluidic platforms offer significant enhancements in throughput, sensitivity, and programmability for automated sample processing and analysis.

  8. 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.

  9. Design and assessment of a microfluidic network system for oxygen transport in engineered tissue.

    PubMed

    Kang, Tae-Yun; Hong, Jung Min; Jung, Jin Woo; Yoo, James J; Cho, Dong-Woo

    2013-01-15

    Oxygen and nutrients cannot be delivered to cells residing in the interior of large-volume scaffolds via diffusion alone. Several efforts have been made to meet the metabolic needs of cells in a scaffold by constructing mass transport channels, particularly in the form of bifurcated networks. In contrast to progress in fabrication technologies, however, an approach to designing an optimal network based on experimental evaluation has not been actively reported. The main objective of this study was to establish a procedure for designing an effective microfluidic network system for a cell-seeded scaffold and to develop an experimental model to evaluate the design. We proposed a process to design a microfluidic network by combining an oxygen transport simulation with biomimetic principles governing biological vascular trees. The simulation was performed with the effective diffusion coefficient (D(e,s)), which was experimentally measured in our previous study. Porous scaffolds containing an embedded microfluidic network were fabricated using the lost mold shape-forming process and salt leaching method. The reliability of the procedure was demonstrated by experiments using the scaffolds. This approach established a practical basis for designing an effective microfluidic network in a cell-seeded scaffold.

  10. A fast prototyping process for fabrication of microfluidic systems on soda-lime glass

    NASA Astrophysics Data System (ADS)

    Lin, Che-Hsin; Lee, Gwo-Bin; Lin, Yen-Heng; Chang, Guan-Liang

    2001-11-01

    This paper describes a fast, low-cost but reliable process for the fabrication of microfluidic systems on soda-lime glass substrates. Instead of using an expensive metal or polisilicon/nitride layer as an etch mask, a thin layer of AZ 4620 positive photoresist (PR) is used for buffered oxide etching (BOE) of soda-lime glass. A novel two-step baking process prolongs the survival time of the PR mask in the etchant, which avoids serious peeling problems of the PR. A new process to remove precipitated particles generated during the etching process is also reported in which the glass substrate is dipped into a 1 M hydrochloride solution. A microfluidic channel with a depth of 35.95±0.39 µm is formed after 40 min BOE in an ultrasonic bath. The resulting channel has a smooth profile with a surface roughness of less than 45.95±7.96 Å. Glass chips with microfluidic channels are then bonded at 580 °C for 20 min to seal the channel while a slight pressure is applied. A new bonding process has been developed such that the whole process can be finished within 10 h. To our knowledge, this is the shortest processing time that has ever been reported. In the present study, an innovative microfluidic device, a `micro flow-through sampling chip', has been demonstrated using the fabrication method. Successful sampling and separation of Cy5-labelled bovine serum albumin (BSA) and anti-BSA has been achieved. This simple fabrication process is suitable for fast prototyping and mass production of microfluidic systems.

  11. The effect of captopril on thallium 201 myocardial perfusion in systemic sclerosis

    SciTech Connect

    Kahan, A.; Devaux, J.Y.; Amor, B.; Menkes, C.J.; Weber, S.; Venot, A.; Strauch, G. )

    1990-04-01

    In systemic sclerosis, abnormalities of myocardial perfusion are common and may be caused by a disturbance of the coronary microcirculation. We evaluated the long-term effect of captopril (75 to 150 mg per day) on thallium 201 myocardial perfusion in 12 normotensive patients with systemic sclerosis. Captopril significantly decreased the mean (+/- SD) number of segments with thallium 201 myocardial perfusion defects (6.5 +/- 1.9 at baseline and 4.4 +/- 2.7 after 1 year of treatment with captopril; p less than 0.02) and increased the mean global thallium score (9.6 +/- 1.7 at baseline and 11.4 +/- 2.1 after captopril; p less than 0.05). In a control group of eight normotensive patients with systemic sclerosis who did not receive captopril, no significant modification in thallium results occurred. Side effects with captopril included hypotension (six patients), taste disturbances (one patient), and skin rash (one patient). These side effects subsided when the dosage was reduced. These findings demonstrate that captopril improves thallium 201 myocardial perfusion in patients with systemic sclerosis and may therefore have a beneficial effect on scleroderma myocardial disease.

  12. 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.

  13. Myocardial perfusion scintigraphy and coronary disease risk factors in systemic lupus erythematosus

    PubMed Central

    Sella, E; Sato, E; Leite, W; Filho, J; Barbieri, A

    2003-01-01

    Objective: To evaluate the prevalence of myocardial perfusion abnormalities and the possible association between myocardial perfusion defects and traditional coronary artery disease (CAD) risk factors as well as systemic lupus erythematosus (SLE) related risk factors. Patients and methods: Female patients with SLE, disease duration >5 years, age 18–55 years, who had used steroids for at least one year were enrolled. Traditional CAD risk factors evaluated were arterial hypertension, diabetes mellitus, dyslipidaemia, postmenopausal status, smoking, obesity, and premature family CAD profile. Myocardial perfusion scintigraphy was evaluated by single photon emission computed tomography with technetium 99m-sestamibi at rest and after dipyridamole induced stress. Results: Eight two female patients with SLE without angina pectoris with mean (SD) age 37 (10) years, disease duration 127 (57) months, SLE Disease Activity Index (SLEDAI) score 6 (5), and SLICC/ACR-DI score 2 (2) were evaluated. Myocardial perfusion abnormalities were found in 23 patients (28%). The mean (SD) number of CAD risk factors was 2.2 (1.6). There was a significant positive correlation between age and number of CAD risk factors. Lower high density lipoprotein (HDL) cholesterol level showed a significant association with abnormal scintigraphy. Logistic regression analysis showed that lower HDL cholesterol level and diabetes mellitus were associated with myocardial perfusion abnormalities. Current vasculitis was also associated with abnormal scintigraphy. Conclusions: Lower HDL cholesterol level and diabetes mellitus have a significant influence on abnormal myocardial perfusion results found in asymptomatic patients with SLE. Current vasculitis was associated with abnormal myocardial scintigraphy. These data suggest that abnormal myocardial scintigraphy may be related to subclinical atherosclerosis. PMID:14583569

  14. Hematologic derangements of cardiopulmonary bypass: a comparison of two perfusion systems.

    PubMed

    Zirbel, G M; Letson, M E; Kauffman, J N; Walker, C T; Guyton, R A

    1990-01-01

    A major goal of new perfusion equipment is minimal trauma to blood elements. This study compares two perfusion systems, quantifies the change in blood components and generation of microemboli, as well as compares the hospital courses of each perfusion system. Forty-four coronary patients were assigned to either Group S, a silicone rubber membrane (SciMed) and centrifugal pump (Bio-Medicus) (N=19) or Group C (our routine equipment), a microporous polypropylene membrane (COBE CML) and roller pump (COBE) (N=25). The rise in plasma hemoglobin (26+/-14mg* in Group S and 26+/-17mg* in Group C), the drop in hematocrit (-15.0+/-3.9* in Group S and -14.7+/-3.8* in Group C at the second post-op day), and the decrease in platelet count (-152,000+/-78,000* in Group S and -129,000+/-52,000* in Group C) were similar in both groups. There was no difference in rise in post-op alveolar-arterial oxygen gradients or debris generated by each system. 27.7% in Group S required red cell transfusions and only 8% required red cell transfusions in Group C. There was no significant difference in clinical endpoints such as ICU stay, hospital stay and complication rate. We found no advantage to more expensive perfusion devices and no improvement upon the extensive CPB damage to formed blood elements. * p less than .001

  15. A tetra-layer microfluidic system for peptide affinity screening through integrated sample injection.

    PubMed

    Wang, Weizhi; Huang, Yanyan; Jin, Yulong; Liu, Guoquan; Chen, Yi; Ma, Huimin; Zhao, Rui

    2013-05-21

    A novel integrated microfluidic system was designed and fabricated for affinity peptide screening with in situ detection. A tetra-layer microfluidic hybrid chip containing two top eccentric diffluent layers, an inter-layer and a bottom screening layer, was developed as the core device of the system. The eccentric diffluent layers were ingeniously invented for the vertical sample delivery from 2 top-inlets into 12 bottom-inlets, which eliminated the use of excessive accessories and complicated pipelines currently used in other systems. By using six pH gradient generators, the magnetic bead-based screening in 36 parallel chambers was simultaneously carried out under 6 different pH conditions from 5.4 to 8.2. This allowed simultaneous screening of 6 compounds and each under 6 different pH conditions. The fabricated chip system was applied to screening of affinity peptides towards β-endorphin antibody. The affinities of the peptide ligands to the antibody were assessed by on-chip confocal detection. The results from the screening study using this system indicated that the pentapeptide with the sequence of YGGFL had the highest affinity towards β-endorphin antibody at pH 7.1, which was further confirmed by the ELISA assay using a 96-well plate format. This microfluidic screening system is automatic, low-cost and reusable for not only peptide screening but also other bioactive compounds screening towards target molecules.

  16. A microfluidic two-pump system inspired by liquid feeding in mosquitoes

    NASA Astrophysics Data System (ADS)

    Marino, Andrew; Goad, Angela; Stremler, Mark; Socha, John; Jung, Sunghwan

    Mosquitoes feed on nectar and blood using a two-pump system in the head-a smaller cibarial pump in line with a larger a pharyngeal pump, with a valve in between. To suck, mosquitoes transport the liquid (which may be a multi-component viscous fluid, blood) through a long micro-channel, the proboscis. In the engineering realm, microfluidic devices in biomedical applications, such as lab-on-a-chip technology, necessitate implementing a robust pump design to handle clogging and increase flow control compared to a single-pump system. In this talk, we introduce a microfluidic pump design inspired by the mosquito's two-pump system. The pumping performance (flow rate) in presence of impurities (air bubbles, soft clogs) is quantified as a function of phase difference and volume expansion of the pumps, and the elasticity of the valve.

  17. Shear contributions to cell culture performance and product recovery in ATF and TFF perfusion systems.

    PubMed

    Wang, Samantha; Godfrey, Scott; Ravikrishnan, Janani; Lin, Henry; Vogel, Jens; Coffman, Jon

    2017-03-20

    Achievement of a robust and scalable cell retention device remains a challenge in perfusion systems. Of the two filtration systems commonly used, tangential flow filtration (TFF) systems often have an inferior product sieving profile compared to alternating tangential flow filtration (ATF) systems, which is typically attributed to the ATF's unique alternating flow. Here, we demonstrate that observed performance differences between the two systems are a function of cell lysis and not the alternating flow as previously thought. The peristaltic pump used in typical TFF perfusion systems is shown to be the single major contributor to shear stress and cell lysis. Replacing the peristaltic pump with a low shear centrifugal pump brought cell growth, cell lysis, particle concentration, and product sieving in a TFF perfusion system to levels comparable with that of an ATF. These results provide a correlation where poor product sieving can be partially explained by high shear in cell retention systems and demonstrate that low shear TFF systems are a feasible alternative to ATF systems. Copyright © 2017 Boehringer Ingelheim. Published by Elsevier B.V. All rights reserved.

  18. TOPICAL REVIEW: The measurement of diffusion and perfusion in biological systems using magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Thomas, David L.; Lythgoe, Mark F.; Pell, Gaby S.; Calamante, Fernando; Ordidge, Roger J.

    2000-08-01

    The aim of this review is to describe two recent developments in the use of magnetic resonance imaging (MRI) in the study of biological systems: diffusion and perfusion MRI. Diffusion MRI measures the molecular mobility of water in tissue, while perfusion MRI measures the rate at which blood is delivered to tissue. Therefore, both these techniques measure quantities which have direct physiological relevance. It is shown that diffusion in biological systems is a complex phenomenon, influenced directly by tissue microstructure, and that its measurement can provide a large amount of information about the organization of this structure in normal and diseased tissue. Perfusion reflects the delivery of essential nutrients to tissue, and so is directly related to its status. The concepts behind the techniques are explained, and the theoretical models that are used to convert MRI data to quantitative physical parameters are outlined. Examples of current applications of diffusion and perfusion MRI are given. In particular, the use of the techniques to study the pathophysiology of cerebral ischaemia/stroke is described. It is hoped that the biophysical insights provided by this approach will help to define the mechanisms of cell damage and allow evaluation of therapies aimed at reducing this damage.

  19. The measurement of diffusion and perfusion in biological systems using magnetic resonance imaging.

    PubMed

    Thomas, D L; Lythgoe, M F; Pell, G S; Calamante, F; Ordidge, R J

    2000-08-01

    The aim of this review is to describe two recent developments in the use of magnetic resonance imaging (MRI) in the study of biological systems: diffusion and perfusion MRI. Diffusion MRI measures the molecular mobility of water in tissue, while perfusion MRI measures the rate at which blood is delivered to tissue. Therefore, both these techniques measure quantities which have direct physiological relevance. It is shown that diffusion in biological systems is a complex phenomenon, influenced directly by tissue microstructure, and that its measurement can provide a large amount of information about the organization of this structure in normal and diseased tissue. Perfusion reflects the delivery of essential nutrients to tissue, and so is directly related to its status. The concepts behind the techniques are explained, and the theoretical models that are used to convert MRI data to quantitative physical parameters are outlined. Examples of current applications of diffusion and perfusion MRI are given. In particular, the use of the techniques to study the pathophysiology of cerebral ischaemia/stroke is described. It is hoped that the biophysical insights provided by this approach will help to define the mechanisms of cell damage and allow evaluation of therapies aimed at reducing this damage.

  20. 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.

  1. An electromagnetic microvalve for pneumatic control of microfluidic systems.

    PubMed

    Liu, Xuling; Li, Songjing

    2014-10-01

    An electromagnetic microvalve for pneumatic control of microfluidic devices has been designed, fabricated, and tested. The microvalve is composed of two parts: a miniature electromagnetic actuator and a valve body. The electromagnetic actuator consists mainly of a thin polydimethylsiloxane (PDMS)-based elastomer, which acts as the valve diaphragm. The diaphragm, used as a solid hydraulic medium, converts the large contact area of a valve core into a small contact area of valve head while maintaining a large stroking force. This microvalve remains closed because of a compressed mechanical spring force generated by the actuator. On the other hand, when a voltage is applied, the valve core moves up, relaxing the thin PDMS membrane, opening the microvalve. The fast open response (~17 ms) of the valve was achieved with a leak rate as low as 0.026 sccm at 200 KPa (N2) pressure. We tested the pertinent dynamic parameters such as flow rate in on/off mode, flow rate of duty cycles, and actuated frequencies in pulse width modulation (PWM) mode. Our method provides a simple, cheap, and small microvalve that avoids the bulky and expensive external pressure control solenoid manifold. This allows it to be easily integrated into portable and disposable devices.

  2. Lattice Boltzmann Simulation of Particle Laden Flows in Microfluidic Systems

    SciTech Connect

    Clague, D S; Weisgraber, T; Wheeler, E; Hon, G; Radford, J; Gascoyne, P; Smity, R; Liepmann, D; Meinhart, C; Santiago, J; Krulevitch, P

    2003-07-22

    The goal of this effort was to develop dynamic simulation tools to study and characterize particulate transport in Microfluidic devices. This includes the effects of external fields and near-field particle-particle, particle-surface interactions. The unique aspect of this effort is that we focused on the particles in suspension and rigorously accounted for all of the interactions that they experienced in solution. In contrast, other numerical methods within the program, finite element and finite volume approaches, typically treat the suspended species as non-interacting point particles. Later in the program, some of these approaches incorporated approximations to begin to account for particle-particle interactions. Through the programs (BioFlips and SIMBIOSYS), we developed collaborative relationships with device-oriented efforts. More specifically and at the request of the SIMBIOSYS program manager, we allowed our efforts/milestones to be more guided by the needs of our BioFlips colleagues; therefore, our efforts were focused on the needs of the MD Anderson Cancer Center (Peter Gascoyne), UCDavis (Rosemary Smith), and UC Berkeley (Dorian Liepmann). The first two collaborations involved the development of Dielectrophoresis analysis tools and the later involved the development of suspension and fluid modeling tools for microneedles.

  3. An electric stimulation system for electrokinetic particle manipulation in microfluidic devices

    NASA Astrophysics Data System (ADS)

    Lopez-de la Fuente, M. S.; Moncada-Hernandez, H.; Perez-Gonzalez, V. H.; Lapizco-Encinas, B. H.; Martinez-Chapa, S. O.

    2013-03-01

    Microfluidic devices have grown significantly in the number of applications. Microfabrication techniques have evolved considerably; however, electric stimulation systems for microdevices have not advanced at the same pace. Electric stimulation of micro-fluidic devices is an important element in particle manipulation research. A flexible stimulation instrument is desired to perform configurable, repeatable, automated, and reliable experiments by allowing users to select the stimulation parameters. The instrument presented here is a configurable and programmable stimulation system for electrokinetic-driven microfluidic devices; it consists of a processor, a memory system, and a user interface to deliver several types of waveforms and stimulation patterns. It has been designed to be a flexible, highly configurable, low power instrument capable of delivering sine, triangle, and sawtooth waveforms with one single frequency or two superimposed frequencies ranging from 0.01 Hz to 40 kHz, and an output voltage of up to 30 Vpp. A specific stimulation pattern can be delivered over a single time period or as a sequence of different signals for different time periods. This stimulation system can be applied as a research tool where manipulation of particles suspended in liquid media is involved, such as biology, medicine, environment, embryology, and genetics. This system has the potential to lead to new schemes for laboratory procedures by allowing application specific and user defined electric stimulation. The development of this device is a step towards portable and programmable instrumentation for electric stimulation on electrokinetic-based microfluidic devices, which are meant to be integrated with lab-on-a-chip devices.

  4. An electric stimulation system for electrokinetic particle manipulation in microfluidic devices.

    PubMed

    Lopez-de la Fuente, M S; Moncada-Hernandez, H; Perez-Gonzalez, V H; Lapizco-Encinas, B H; Martinez-Chapa, S O

    2013-03-01

    Microfluidic devices have grown significantly in the number of applications. Microfabrication techniques have evolved considerably; however, electric stimulation systems for microdevices have not advanced at the same pace. Electric stimulation of micro-fluidic devices is an important element in particle manipulation research. A flexible stimulation instrument is desired to perform configurable, repeatable, automated, and reliable experiments by allowing users to select the stimulation parameters. The instrument presented here is a configurable and programmable stimulation system for electrokinetic-driven microfluidic devices; it consists of a processor, a memory system, and a user interface to deliver several types of waveforms and stimulation patterns. It has been designed to be a flexible, highly configurable, low power instrument capable of delivering sine, triangle, and sawtooth waveforms with one single frequency or two superimposed frequencies ranging from 0.01 Hz to 40 kHz, and an output voltage of up to 30 Vpp. A specific stimulation pattern can be delivered over a single time period or as a sequence of different signals for different time periods. This stimulation system can be applied as a research tool where manipulation of particles suspended in liquid media is involved, such as biology, medicine, environment, embryology, and genetics. This system has the potential to lead to new schemes for laboratory procedures by allowing application specific and user defined electric stimulation. The development of this device is a step towards portable and programmable instrumentation for electric stimulation on electrokinetic-based microfluidic devices, which are meant to be integrated with lab-on-a-chip devices.

  5. Finger-powered microfluidic systems using multilayer soft lithography and injection molding processes.

    PubMed

    Iwai, Kosuke; Shih, Kuan Cheng; Lin, Xiao; Brubaker, Thomas A; Sochol, Ryan D; Lin, Liwei

    2014-10-07

    Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems with pumping components that provide controlled pressure sources. Unfortunately, external pumps have hindered the implementation of such microfluidic systems due to limitations associated with portability and power requirements. Here, we propose and demonstrate a 'finger-powered' integrated pumping system as a modular element to provide pressure head for a variety of advanced microfluidic applications, including finger-powered on-chip microdroplet generation. By utilizing a human finger for the actuation force, electrical power sources that are typically needed to generate pressure head were obviated. Passive fluidic diodes were designed and implemented to enable distinct fluids from multiple inlet ports to be pumped using a single actuation source. Both multilayer soft lithography and injection molding processes were investigated for device fabrication and performance. Experimental results revealed that the pressure head generated from a human finger could be tuned based on the geometric characteristics of the pumping system, with a maximum observed pressure of 7.6 ± 0.1 kPa. In addition to the delivery of multiple, distinct fluids into microfluidic channels, we also employed the finger-powered pumping system to achieve the rapid formation of both water-in-oil droplets (106.9 ± 4.3 μm in diameter) and oil-in-water droplets (75.3 ± 12.6 μm in diameter) as well as the encapsulation of endothelial cells in droplets without using any external or electrical controllers.

  6. Microfluidics-Based Lab-on-Chip Systems in DNA-Based Biosensing: An Overview

    PubMed Central

    Dutse, Sabo Wada; Yusof, Nor Azah

    2011-01-01

    Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment. PMID:22163925

  7. Laser ablated micropillar energy directors for ultrasonic welding of microfluidic systems

    NASA Astrophysics Data System (ADS)

    Esben Poulsen, Carl; Kistrup, Kasper; Korsgaard Andersen, Nis; Taboryski, Rafael; Fougt Hansen, Mikkel; Wolff, Anders

    2016-06-01

    We present a new type of energy director (ED) for ultrasonic welding of microfluidic systems. These micropillar EDs are based on the replication of cone like protrusion structures introduced using a pico-second laser and may therefore be added to any mould surface accessible to a pico-second laser beam. The technology is demonstrated on an injection moulded microfluidic device featuring high-aspect ratio (h  ×  w  =  2000 μm  ×  550 μm) and free-standing channel walls, where bonding is achieved with no detectable channel deformation. The bonding strength is similar to conventional EDs and the fabricated system can withstand pressures of over 9.5 bar.

  8. Microfluidics-based lab-on-chip systems in DNA-based biosensing: an overview.

    PubMed

    Dutse, Sabo Wada; Yusof, Nor Azah

    2011-01-01

    Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment.

  9. 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.

  10. Hydrodynamic directional control of liquid metal droplets within a microfluidic flow focusing system

    NASA Astrophysics Data System (ADS)

    Gol, Berrak; Kurdzinski, Michael E.; Tovar-Lopez, Francisco J.; Petersen, Phred; Mitchell, Arnan; Khoshmanesh, Khashayar

    2016-04-01

    Here, we investigate the directional control of Galinstan liquid metal droplets when transferring from the high-viscosity glycerol core into the parallel low-viscosity NaOH sheath streams within a flow focusing microfluidic system. In the presence of sufficient flow mismatch between the sheath streams, the droplets are driven toward the higher velocity interface and cross the interface under the influence of surface tension gradient. A minimum flow mismatch of 125 μl/min is required to enable the continuous transfer of droplets toward the desired sheath stream. The response time of droplets, the time required to change the direction of droplet transfer, is governed by the response time of the syringe pump driven microfluidic system and is found to be 3.3 and 8.8 s when increasing and decreasing the flow rate of sheath stream, respectively.

  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. Detection of viruses directly from the fresh leaves of a Phalaenopsis orchid using a microfluidic system.

    PubMed

    Chang, Wen-Hsin; Yang, Sung-Yi; Lin, Chih-Lin; Wang, Chih-Hung; Li, Ping-Chen; Chen, Tzong-Yueh; Jan, Fuh-Jyh; Lee, Gwo-Bin

    2013-11-01

    Early detection of pathogens is crucial for the effective surveillance of diseases. Many efforts have been made to explore methods which can detect these pathogens within a short period of time without requiring a tedious protocol. However, these developed methods have disadvantages such as they are relatively time-consuming or require specialized laboratory facilities. In this work, we have developed an integrated microfluidic system for rapid and automatic detection of viruses by direct analysis from fresh Phalaenopsis orchid leaves. The entire protocol, including ribonucleic acid (RNA) purification, reverse transcription loop-mediated-isothermal-amplification (RT-LAMP) and optical detection by measuring changes in turbidity was performed on a single chip. This is the first time that an integrated microfluidic system for the detection of viruses infecting the Phalaenopsis orchid has been demonstrated. The sensitivity of the developed system was also explored in this study to validate its performance. In this study, the authors report the development of an integrated microfluidic system for rapid and automatic detection of viruses by direct analysis of fresh Phalaenopsis orchid leaves, performing the 3-step protocol using a single chip. Similar methods may find clinical application for fast and accurate detection of viral infections. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Monitoring the status of T-cell activation in a microfluidic system.

    PubMed

    Park, Joo Young; Kim, Hyun Ok; Kim, Kyun-Do; Kim, Sung Kyu; Lee, Sang Kyou; Jung, Hyungil

    2011-07-07

    Leukocyte adhesion to the endothelium through surface molecules such as E-selectin and intercellular adhesion molecule-1 (ICAM-1) is a critical cellular event reflecting the physiological status of both cell types. Here we present a microfluidic system that can not only easily monitor the interaction between leukocytes and endothelial cells under physiological conditions, but also screen drug candidates for potential modulation of this interaction. Shear stress, which is an important factor for the binding of activated T cells to tumor necrosis factor-alpha (TNF-α)-treated human umbilical vein endothelial cells (HUVECs), was easily controlled by adjusting the flow rate in the microfluidic system. Whole blood of patients with systemic lupus erythematosus (SLE) who have auto-reactive T cells were infused into the activated HUVECs which subsequently showed a higher level of binding compared to a control blood sample from a person without SLE. When these autoreactive T cells were treated with immunosuppressors tacrolimus and cyclosporin A, the binding of the T cells to HUVECs was dramatically decreased. Therefore, this microfluidic system is capable of differentiating the physiological status of T cells or endothelial cells representing different disease conditions, as well as being useful for the identification of novel reagents that modulate the functions of leukocytes or endothelial cells.

  14. A Surface Acoustic Wave Pumped Lensless Microfluidic Imaging System for Flowing Cell Detection and Counting.

    PubMed

    Huang, Xiwei; Farooq, Umar; Chen, Jin; Ge, Yakun; Gao, Haijun; Su, Jiangtao; Wang, Xiang; Dong, Shurong; Luo, Ji-Kui

    2017-08-29

    The future point-of-care diagnostics requires miniaturizing the existing bulky and expensive bioanalysis instruments, where lab-on-CMOS-chip-based technology can provide a promising solution. In this paper, we presented a surface acoustic wave (SAW) pumped lensless microfluidic imaging system for flowing cell detection and counting. Different from the previous lensless systems, which employ external bulky syringe pump for cell driven, the developed system directly integrates the SAW pump on the CMOS image sensor chip to drive the cell-containing microfluid. Moreover, an efficient temporal-differencing-based motion detection algorithm is proposed for continuous flowing cell detection and counting. Experimental results show that the SAW pump can drive the cells to flow at different driven powers, and also can keep the channel temperature below 40 °C so as not to harm the cells. The human bone marrow stromal cells flowing in the microfluidic channel can be automatically detected and counted with a low statistical error rate of -6.53%. The developed system thereby is competitive for point-of-care cell detection and counting application.

  15. A novel portable perfused manometric system for recording of small intestinal motility.

    PubMed

    Samsom, M; Smout, A J; Hebbard, G; Fraser, R; Omari, T; Horowitz, M; Dent, J

    1998-04-01

    The development of solid-state catheters with miniature pressure transducers and portable dataloggers with a large memory capacity has allowed recording of gastrointestinal motility in ambulant subjects. Developments in silicone rubber extrusion technology made it possible to build a perfused manometric system, using a perfused manometric assembly requiring a low volume of perfusate. In the present study the feasibility of recording and automated analysis of small intestinal motility using a perfused multiple lumen manometric system was evaluated in seven healthy volunteers. Pressures were recorded from 12 sideholes arranged in four clusters spaced at 10-cm intervals from the catheter tip. Each channel was perfused at 0.15 mL min-1 with degassed water by a portable, low-compliance, perfusion pump. The 12 sidehole recording channels were connected to external transducers mounted on a belt. Pressure data were stored in two dataloggers. Motility was recorded in the sitting (30 min), and supine (30 min) position, during walking (30 min) and postprandially (90 min). Using purpose-built software baseline variations were corrected for and manometric variables (number of pressure waves, mean amplitude and motility index) calculated. Bench testing of the manometric assembly showed a median baseline pressure offset of 4.2 kPa (range 3.7-10.1) and upon occlusion a rise rate of 27.8 kPa sec-1 (range 19.7-30.8). Changes in body position affected baseline pressures so that compared to the supine position changes in baseline pressure varied between 1.5 +/- 0.7 kPa and 1.9 +/- 0.6 kPa during sitting (P < 0.02), and between 1.7 +/- 0.7 kPa and 1.5 +/- 0.9 kPa during walking (P < 0.03). Manometric recordings obtained during the fasting period showed an increase in small intestinal motor activity during walking. In the postprandial period no differences in motility variables were observed within one cluster and in time. Recording of small intestinal motility with a multiple

  16. Microfluidic fuel cell systems with embedded materials and structures and method thereof

    DOEpatents

    Morse, Jeffrey D.; Rose, Klint A; Maghribi, Mariam; Benett, William; Krulevitch, Peter; Hamilton, Julie; Graff, Robert T.; Jankowski, Alan

    2005-07-26

    Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.

  17. Measurement of reaction kinetics of [(177)Lu]Lu-DOTA-TATE using a microfluidic system.

    PubMed

    Liu, Z; Schaap, K S; Ballemans, L; de Zanger, R; de Blois, E; Rohde, M; Oehlke, E

    2017-09-12

    Microfluidic synthesis techniques can offer improvement over batch syntheses which are currently used for radiopharmaceutical production. These improvements are, for example, better mixing of reactants, more efficient energy transfer, less radiolysis, faster reaction optimization, and overall improved reaction control. However, scale-up challenges hinder the routine clinical use, so the main advantage is currently the ability to optimize reactions rapidly and with low reactant consumption. Translating those results to clinical systems could be done based on calculations, if kinetic constants and diffusion coefficients were known. This study describes a microfluidic system with which it was possible to determine the kinetic association rate constants for the formation of [(177)Lu]Lu-DOTA-TATE under conditions currently used for clinical production. The kinetic rate constants showed a temperature dependence that followed the Arrhenius equation, allowing the determination of Arrhenius parameters for a Lu-DOTA conjugate (A = 1.24 ± 0.05 × 10(19) M(-1) s(-1), EA = 109.5 ± 0.1 × 10(3) J mol(-1)) for the first time. The required reaction time for the formation of [(177)Lu]Lu-DOTA-TATE (99% yield) at 80 °C was 44 s in a microfluidic channel (100 μm). Simulations done with COMSOL Multiphysics® indicated that processing clinical amounts (3 mL reaction solution) in less than 12 min is possible in a micro- or milli-fluidic system, if the diameter of the reaction channel is increased to over 500 μm. These results show that a continuous, microfluidic system can become a viable alternative to the conventional, batch-wise radiolabelling technique.

  18. 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

  19. A modular microfluidic system for deoxyribonucleic acid identification by short tandem repeat analysis.

    PubMed

    Reedy, Carmen R; Hagan, Kristin A; Marchiarullo, Daniel J; Dewald, Alison H; Barron, Annalise; Bienvenue, Joan M; Landers, James P

    2011-02-21

    Microfluidic technology has been utilized in the development of a modular system for DNA identification through STR (short tandem repeat) analysis, reducing the total analysis time from the ∼6 h required with conventional approaches to less than 3h. Results demonstrate the utilization of microfluidic devices for the purification, amplification, separation and detection of 9 loci associated with a commercially-available miniSTR amplification kit commonly used in the forensic community. First, DNA from buccal swabs purified in a microdevice was proven amplifiable for the 9 miniSTR loci via infrared (IR)-mediated PCR (polymerase chain reaction) on a microdevice. Microchip electrophoresis (ME) was then demonstrated as an effective method for the separation and detection of the chip-purified and chip-amplified DNA with results equivalent to those obtained using conventional separation methods on an ABI 310 Genetic Analyzer. The 3-chip system presented here demonstrates development of a modular, microfluidic system for STR analysis, allowing for user-discretion as to how to proceed after each process during the analysis of forensic casework samples. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. A microfluidic system integrated with buried optical fibers for detection of Phalaenopsis orchid pathogens.

    PubMed

    Lin, Chih-Lin; Chang, Wen-Hsin; Wang, Chih-Hung; Lee, Chia-Hwa; Chen, Tzong-Yueh; Jan, Fuh-Jyh; Lee, Gwo-Bin

    2015-01-15

    Orchids of the genus Phalaenopsis are some of the most economically important plants in Taiwan. Fast, accurate, and on-site detection of pathogens in these orchids is therefore of critical importance in order to prevent or suppress costly disease outbreaks. Traditional pathogen detection methods are time-consuming, require well-equipped laboratories with highly trained personnel, and cannot be conducted in situ. In this study, a microfluidic system integrated with buried optical fibers was developed to detect viral pathogens of Phalaenopsis spp. Briefly, virus-specific ribonucleic acid (RNA) purification was achieved by a pre-treatment incubation with magnetic beads, and reverse-transcription loop-mediated isothermal amplification (RT-LAMP) was used subsequently to amplify the viral RNA. Positive RT-LAMP reactions resulted in the precipitation of magnesium pyrophosphate, which caused a change in turbidity that could be seen by the naked eye. A buried optical fiber-based detection module and a micro-stirring device were then integrated into the microfluidic chip to detect the RT-LAMP reaction product directly on the chip itself by measuring the change in the optical signals caused by the turbidity change associated with a positive amplification. The limit of detection for this system was found to be 25 fg, which is of similar sensitivity to existing, more laborious methods. Therefore, by using the integrated microfluidic system, a sensitive, rapid, accurate, and automatic diagnosis of viral pathogens in Phalaenopsis spp. orchids could be achieved within only 65 min.

  1. Immunomagnetic Nanoscreening of Circulating Tumor Cells with a Motion Controlled Microfluidic System

    PubMed Central

    Huang, Yu-Yen; Hoshino, Kazunori; Chen, Peng; Wu, Chung-Hsien; Lane, Nancy; Huebschman, Michael; Liu, Huaying; Sokolov, Konstantin; Uhr, Jonathan W.; Frenkel, Eugene P.

    2012-01-01

    Combining the power of immunomagnetic assay and microfluidic microchip operations, we successfully detected rare CTCs from clinical blood samples. The microfluidic system is operated in a flip-flop mode, where a computer-controlled rotational holder with an array of microfluidic chips inverts the microchannels. We have demonstrated both theoretically and experimentally that the direction of red blood cell (RBC) sedimentation with regards to the magnetic force required for cell separation is important for capture efficiency, throughput, and purity. The flip-flop operation reduces the stagnation of RBCs and non-specific binding on the capture surface by alternating the direction of the magnetic field with respect to gravity. The developed immunomagnetic microchip-based screening system exhibits high capture rates (more than 90%) for SkBr3, PC3, and Colo205 cell lines in spiked screening experiments and successfully isolates CTCs from patient blood samples. The proposed motion controlled microchip-based immunomagnetic system shows great promise as a clinical tool for cancer diagnosis and prognosis. PMID:23109037

  2. Easy route to superhydrophobic copper-based wire-guided droplet microfluidic systems.

    PubMed

    Mumm, Florian; van Helvoort, Antonius T J; Sikorski, Pawel

    2009-09-22

    Droplet-based microfluidic systems are an expansion of the lab on a chip concept toward flexible, reconfigurable setups based on the modification and analysis of individual droplets. Superhydrophobic surfaces are one suitable candidate for the realization of droplet-based microfluidic systems as the high mobility of aqueous liquids on such surfaces offers possibilities to use novel or more efficient approaches to droplet movement. Here, copper-based superhydrophobic surfaces were produced either by the etching of polycrystalline copper samples along the grain boundaries using etchants common in the microelectronics industry, by electrodeposition of copper films with subsequent nanowire decoration based on thermal oxidization, or by a combination of both. The surfaces could be easily hydrophobized with thiol-modified fluorocarbons, after which the produced surfaces showed a water contact angle as high as 171 degrees +/- 2 degrees . As copper was chosen as the base material, established patterning techniques adopted from printed circuit board fabrication could be used to fabricate macrostructures on the surfaces with the intention to confine the droplets and, thus, to reduce the system's sensitivity to tilting and vibrations. A simple droplet-based microfluidic chip with inlets, outlets, sample storage, and mixing areas was produced. Wire guidance, a relatively new actuation method applicable to aqueous liquids on superhydrophobic surfaces, was applied to move the droplets.

  3. Spinning magnetic trap for automated microfluidic assay systems.

    PubMed

    Verbarg, Jasenka; Kamgar-Parsi, Kian; Shields, Adam R; Howell, Peter B; Ligler, Frances S

    2012-04-24

    While sophisticated analyses have been performed using lab-on-chip devices, in most cases the sample preparation is still performed off chip. The global need for easy-to-use, disposable testing devices necessitates that sample processing is automated and that transport complexity between the processing and analytical components is minimal. We describe a complete sample manipulation unit for performing automated target capture, efficient mixing with reagents, and controlled target release in a microfluidic channel, using an array of spinning magnets. The "MagTrap" device consists of 6 pairs of magnets in a rotating wheel, situated immediately beneath the microchannel. Rotation of the wheel in the direction opposite to the continuous flow entraps and concentrates the bead-target complexes and separates them from the original sample matrix. As the wheel rotates and the active pair of magnets moves away from the microchannel, the beads are released and briefly flow downstream before being trapped and pulled upstream by the next pair of magnets. This dynamic and continuous movement of the beads ensures that the full surface area of each bead is exposed to reagents and prevents aggregation. The release of the target-bead complexes for further analysis is facilitated by reversing the rotational direction of the wheel to sweep the beads downstream. Sample processing with the MagTrap was demonstrated for the detection of E. coli in a range of concentrations (1 × 10(3), 1 × 10(4) and 1 × 10(6) cells ml(-1)). Results show that sample processing with the MagTrap outperformed the standard manual protocols, improving the detection capability while simultaneously reducing the processing time.

  4. 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

  5. Combined simulation and experimental study of large deformation of red blood cells in microfluidic systems.

    PubMed

    Quinn, David J; Pivkin, Igor; Wong, Sophie Y; Chiam, Keng-Hwee; Dao, Ming; Karniadakis, George Em; Suresh, Subra

    2011-03-01

    We investigate the biophysical characteristics of healthy human red blood cells (RBCs) traversing microfluidic channels with cross-sectional areas as small as 2.7 × 3 μm. We combine single RBC optical tweezers and flow experiments with corresponding simulations based on dissipative particle dynamics (DPD), and upon validation of the DPD model, predictive simulations and companion experiments are performed in order to quantify cell deformation and pressure-velocity relationships for different channel sizes and physiologically relevant temperatures. We discuss conditions associated with the shape transitions of RBCs along with the relative effects of membrane and cytosol viscosity, plasma environments, and geometry on flow through microfluidic systems at physiological temperatures. In particular, we identify a cross-sectional area threshold below which the RBC membrane properties begin to dominate its flow behavior at room temperature; at physiological temperatures this effect is less profound.

  6. Combined Simulation and Experimental Study of Large Deformation of Red Blood Cells in Microfluidic Systems

    PubMed Central

    Quinn, David J.; Pivkin, Igor; Wong, Sophie Y.; Chiam, Keng-Hwee; Dao, Ming; Karniadakis, George Em; Suresh, Subra

    2011-01-01

    We investigate the biophysical characteristics of healthy human red blood cells (RBCs) traversing microfluidic channels with cross-sectional areas as small as 2.7 × 3 μm. We combine single RBC optical tweezers and flow experiments with corresponding simulations based on dissipative particle dynamics (DPD), and upon validation of the DPD model, predictive simulations and companion experiments are performed in order to quantify cell deformation and pressure–velocity relationships for different channel sizes and physiologically relevant temperatures. We discuss conditions associated with the shape transitions of RBCs along with the relative effects of membrane and cytosol viscosity, plasma environments, and geometry on flow through microfluidic systems at physiological temperatures. In particular, we identify a cross-sectional area threshold below which the RBC membrane properties begin to dominate its flow behavior at room temperature; at physiological temperatures this effect is less profound. PMID:21240637

  7. Modeling and simulation of DNA flow in a microfluidic-based pathogen detection system

    SciTech Connect

    Trebotich, D; Miller, G H

    2005-01-31

    We present simulation results from a new computational model of DNA flow in microfluidic devices. This work is important because computational models are needed to design miniaturized biomedical devices that are becoming the state-of-the-art in many significant applications including pathogen detection as well as continuous monitoring and drug delivery. Currently advanced algorithms in design tools are non-existent but necessary to understand the complex fluid and polymer dynamics involved in biological flow at small scales. Our model is based on a fully coupled fluid-particle numerical algorithm with both stochastic and deterministic components in a bead-rod polymer representation. We have applied this work to DNA extraction configurations in a microfluidic PCR chamber used in a pathogen detection system. We demonstrate our method on the test problem of flow of a single DNA molecule in a 2D packed array microchannel. We are also investigating mechanisms for molecular ''sticking'' using short range forces.

  8. Ex Vivo Machine Perfusion in VCA with a Novel Oxygen Carrier System to Enhance Graft Preservation and Immunologic Outcomes

    DTIC Science & Technology

    2016-12-01

    Distribution Unlimited Page 1 AWARD NUMBER: W81XWH-13-2-0061 TITLE: “Ex Vivo Machine Perfusion in VCA with a Novel Oxygen Carrier System to...ADDRESS. 1. REPORT DATE December 2016 2. REPORT TYPE Final 3. DATES COVERED 15 Sep 2013 – 14 Sep 2016 4. TITLE AND SUBTITLE Ex Vivo Machine ...Perfusion in CTA with a Novel Oxygen Carrier System to Enhance Graft 5a. CONTRACT NUMBER Ex Vivo Machine Perfusion in CTA with a Novel Oxygen Carrier System

  9. 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.

  10. Microfluidic chip system for the selection and enrichment of cell binding aptamers

    PubMed Central

    Stoll, Heidi; Kiessling, Heiko; Stelzle, Martin; Wendel, Hans Peter; Schütte, Julia; Hagmeyer, Britta; Avci-Adali, Meltem

    2015-01-01

    Aptamers are promising cell targeting ligands for several applications such as for the diagnosis, therapy, and drug delivery. Especially, in the field of regenerative medicine, stem cell specific aptamers have an enormous potential. Using the combinatorial chemistry process SELEX (Systematic Evolution of Ligands by Exponential enrichment), aptamers are selected from a huge oligonucleotide library consisting of approximately 1015 different oligonucleotides. Here, we developed a microfluidic chip system that can be used for the selection of cell specific aptamers. The major drawbacks of common cell-SELEX methods are the inefficient elimination of the unspecifically bound oligonucleotides from the cell surface and the unspecific binding/uptake of oligonucleotides by dead cells. To overcome these obstacles, a microfluidic device, which enables the simultaneous performance of dielectrophoresis and electrophoresis in the same device, was designed. Using this system, viable cells can be selectively assembled by dielectrophoresis between the electrodes and then incubated with the oligonucleotides. To reduce the rate of unspecifically bound sequences, electrophoretic fields can be applied in order to draw loosely bound oligonucleotides away from the cells. Furthermore, by increasing the flow rate in the chip during the iterative rounds of SELEX, the selection pressure can be improved and aptamers with higher affinities and specificities can be obtained. This new microfluidic device has a tremendous capability to improve the cell-SELEX procedure and to select highly specific aptamers. PMID:26180568

  11. Single Microfluidic Electrochemical Sensor System for Simultaneous Multi-Pulmonary Hypertension Biomarker Analyses.

    PubMed

    Lee, GeonHui; Lee, JuKyung; Kim, JeongHoon; Choi, Hak Soo; Kim, Jonghan; Lee, SangHoon; Lee, HeaYeon

    2017-08-08

    Miniaturized microfluidic biosensors have recently been advanced for portable point-of-care diagnostics by integrating lab-on-a-chip technology and electrochemical analysis. However, the design of a small, integrated, and reliable biosensor for multiple and simultaneous electrochemical analyses in a single device remains a challenge. Here, we present a simultaneous microfluidic electrochemical biosensing system to detect multiple biomarkers of pulmonary hypertension diseases in a single device. The miniaturized biosensor, which is composed of five chambers, is precisely and individually controlled using in-house-built pneumatic microvalves to manipulate the flow pathway. Each chamber is connected to an electrochemical sensor designed to detect four different biomarkers plus a reference control. Our design allows for loading of multiple reagents for simultaneous analyses. On the basis of the developed microfluidic electrochemical sensor system, we successfully detected four well-defined pulmonary hypertension-associated biomarkers, namely, fibrinogen, adiponectin, low-density lipoprotein, and 8-isoprostane. This novel approach offers a new platform for a rapid, miniaturized, and sensitive diagnostic sensor in a single device for various human diseases.

  12. Micro-fluidic interconnect

    DOEpatents

    Okandan, Murat; Galambos, Paul C.; Benavides, Gilbert L.; Hetherington, Dale L.

    2006-02-28

    An apparatus for simultaneously aligning and interconnecting microfluidic ports is presented. Such interconnections are required to utilize microfluidic devices fabricated in Micro-Electromechanical-Systems (MEMS) technologies, that have multiple fluidic access ports (e.g. 100 micron diameter) within a small footprint, (e.g. 3 mm.times.6 mm). Fanout of the small ports of a microfluidic device to a larger diameter (e.g. 500 microns) facilitates packaging and interconnection of the microfluidic device to printed wiring boards, electronics packages, fluidic manifolds etc.

  13. Optimized preparation of pDNA/poly(ethylene imine) polyplexes using a microfluidic system.

    PubMed

    Debus, Heiko; Beck-Broichsitter, Moritz; Kissel, Thomas

    2012-07-21

    Poly(ethylene imine) (PEI) is an established non-viral vector system for the delivery of various nucleic acids in gene therapy applications. Polyelectrolyte complexes between both compounds, so called polyplexes, are formed by electrostatic interactions of oppositely charged macromolecules and are thought to facilitate uptake into cells. Such complexes form spontaneously and on lab scale they are usually prepared by mixing solutions through pipetting. Hence, an optimized preparation procedure allowing the scale-up of well-defined polyplexes would be of general interest. We developed a new method for microfluidic polyplex preparation on a chip. The mixing behaviour within the microfluidic channels was evaluated. Polyplexes with PEI and plasmid DNA were prepared using this method, in comparison to the standard pipetting procedure. Sizes and polydispersity indices of these complexes were examined. The influence of various parameters on the polyplex characteristics and the suitability of this production procedure for other PEI-based complexes were also evaluated. It was shown that polyplexes could easily be prepared by microfluidics. The ratio of PEI to DNA was most important for the formation of small polyplexes, whereas other parameters had minor influence. The size of polyplexes prepared with this new method was observed to be relatively constant between 140 nm and 160 nm over a wide range of complex concentrations. In comparison, the size of polyplexes prepared by pipetting (approximately 90 nm to 160 nm) varied considerably. The versatility of this system was demonstrated with different (targeted) PEI-based vectors for the formation of complexes with pDNA and siRNA. In conclusion, polyplex preparation using microfluidics could be a promising alternative to the standard pipetting method due to its suitability for preparation of well-defined complexes with different compositions over a wide range of concentrations.

  14. Fabrication and integration of microprism mirrors for high-speed three-dimensional measurement in inertial microfluidic system

    NASA Astrophysics Data System (ADS)

    Koh, Joonyoung; Kim, Jihye; Shin, Jung H.; Lee, Wonhee

    2014-09-01

    Inertial microfluidics utilizes fluid inertia from high flow velocity to manipulate particles and fluids in 3D. Acquiring a 3D information of particle positions and complex flow patterns within microfluidic devices requires 3D imaging techniques such as confocal microscopy, which are often expensive and slow. Here, we report on a prism-mirror-embedded microfluidic device that allows simultaneous imaging of the top and side view of the microchannel for a high-speed, low-cost 3D imaging. The microprism mirrors are fabricated and integrated into a microfluidic system using conventional microfabrication techniques including wet etch and soft lithography. This inexpensive high quality prism mirror provides a highly reflective, smooth mirror surface with precise 45° reflection angle, enabling 3D measurement of inertial migration of microparticles in a rectangular channel at speeds in excess of 10 000 frame/s.

  15. Myocardial perfusion imaging parameters: IQ-SPECT and conventional SPET system comparison.

    PubMed

    Havel, Martin; Kolacek, Michal; Kaminek, Milan; Dedek, Vladimir; Kraft, Otakar; Sirucek, Pavel

    2014-01-01

    Technological advancement in hardware and software development in myocardial perfusion imaging (MPI) leads to the shortening of acquisition time and reduction of the radiation burden to patients. We compared semiquantitative perfusion results and functional parameters of the left ventricle between new dedicated cardiac system with astigmatic collimators called IQ-SPECT (Siemens Medical Solutions, USA) and conventional single photon emission tomography (SPET) system equipped with standard low energy high resolution collimators. A group of randomly selected 81 patients underwent consecutively the MPI procedure on IQ-SPECT and on conventional SPET systen, both without attenuation correction. The summed scores and the values of the functional parameters of the left ventricle: ejection fraction (EF), end-systolic and end-diastolic volumes (ESV, EDV) received from the automatic analysis software were compared and statistically analyzed. Our results showed that summed scores values were significantly higher for the IQ-SPECT system in comparison to the conventional one. Calculated EF were significantly lower for IQ-SPECT, whereas evaluated left ventricular volumes (LVV) were significantly higher for this system. In conclusion, we recorded significant differences in automatically calculated semiquantitative perfusion and functional parameters when compared uncorrected studies obtained by the IQ-SPECT with the conventional SPET system.

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

    NASA Astrophysics Data System (ADS)

    Jayamohan, Harikrishnan

    Monitoring and remediation of environmental contaminants (biological and chemical) form the crux of global water resource management. There is an extant need to develop point-of-use, low-power, low-cost tools that can address this problem effectively with minimal environmental impact. Nanotechnology and microfluidics have made enormous advances during the past decade in the area of biosensing and environmental remediation. The "marriage" of these two technologies can effectively address some of the above-mentioned needs. In this dissertation, nanomaterials were used in conjunction with microfluidic techniques to detect and degrade biological and chemical pollutants. In the first project, a point-of-use sensor was developed for detection of trichloroethylene (TCE) from water. A self-organizing nanotubular titanium dioxide (TNA) synthesized by electrochemical anodization and functionalized with photocatalytically deposited platinum (Pt/TNA) was applied to the detection. The morphology and crystallinity of the Pt/TNA sensor was characterized using field emission scanning electron microscope, energy dis- persive x-ray spectroscopy, and X-ray diffraction. The sensor could detect TCE in the concentrations ranging from 10 to 1000 ppm. The room-temperature operation capability of the sensor makes it less power intensive and can potentially be incorporated into a field-based sensor. In the second part, TNA synthesized on a foil was incorporated into a flow-based microfluidic format and applied to degradation of a model pollutant, methylene blue. The system was demonstrated to have enhanced photocatalytic performance at higher flow rates (50-200 muL/min) over the same microfluidic format with TiO2 nanoparticulate (commercial P25) catalyst. The microfluidic format with TNA catalyst was able to achieve 82% fractional conversion of 18 mM methylene blue in comparison to 55% in the case of the TiO2 nanoparticulate layer at a flow rate of 200 L/min. The microfluidic device was

  17. A Magnetic Resonance (MR) Microscopy System using a Microfluidically Cryo-Cooled Planar Coil

    PubMed Central

    Koo, Chiwan; Godley, Richard F.; Park, Jaewon; McDougall, Mary P.; Wright, Steven M.; Han, Arum

    2011-01-01

    We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (−196°C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: 1) The small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. 2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0°C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system

  18. A magnetic resonance (MR) microscopy system using a microfluidically cryo-cooled planar coil.

    PubMed

    Koo, Chiwan; Godley, Richard F; Park, Jaewon; McDougall, Mary P; Wright, Steven M; Han, Arum

    2011-07-07

    We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (-196 °C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: (1) the small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. (2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0 °C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system

  19. A microfluidic system for long-term time-lapse microscopy studies of mycobacteria.

    PubMed

    Golchin, Solmaz A; Stratford, James; Curry, Richard J; McFadden, Johnjoe

    2012-11-01

    Phenotypic heterogeneity in bacterial populations is thought to contribute to a number of important phenomena including sporulation and persistence. The latter has clinical implications in many diseases such as tuberculosis, where persistence of Mycobacterium tuberculosis within the human host is believed to be the root cause of latent tuberculosis and the ability of a minority population of cells to survive antibiotic exposure, despite being genetically identical to the bulk population that are killed. However, phenotypic variations caused by non-genetic mechanisms are difficult to study because of the transient nature of the persistent state and thereby the requirement to observe individual cells in real-time. Recently, microfluidics, combined with time-lapse microscopy, has become a powerful tool for studying population heterogeneity in bacteria. However, growth and replication of mycobacterial cells provide particular problems for the development of microfluidic systems due to their tendency to grow in three dimensions. We here describe a novel microfluidic device for the observation of growth and antibiotic killing in individual mycobacterial cells. We constructed a microfluidic device suitable for studying single cell behavior in mycobacteria. The growth of single cells of Mycobacterium smegmatis expressing green fluorescent protein was monitored using a confocal laser scanning microscope. Within the device M. smegmatis cells were tightly confined within a hydrogel matrix thus promoting planar growth. Cell growth and killing was observed in the device with dead cells highlighted by uptake of propidium iodide. Conclusions/Significance. We demonstrate that our device allows real-time analysis and long-term culture of single cells of mycobacteria, and is able to support the study of cell death during the application of antibiotics. The device will allow observation of individual cells' cell genealogy to be determined and direct observation of rare states, such

  20. Electrodiffusion Method of Near-Wall Flow Diagnostics in Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Tihona, J.; Pěnkavová, V.; Stanovský, P.; Vejražka, J.

    2015-05-01

    The electrodiffusion technique has been mostly used for the near-wall flow diagnostics on large scales. A novel technique for fabrication of plastic microfluidic systems with integrated metal microelectrodes (called technique of sacrificed substrate) enables us to produce microfluidic devices with precisely shaped sensors for wall shear stress measurements. Several micrometer thick gold sensors, which are built-in a plastic substrate, exhibit good mechanical resistance and smoothness. Proper functioning of prepared chips with microsensors has been first tested in various calibration experiments (polarization curve, sensor response to polarization set-up, steady flow calibration, temperature dependence of diffusivity). Our first results obtained for separating/reattaching flow behind a backward-facing step and for gas-liquid Taylor flow in microchannels then demonstrate its applicability for the detection of near-wall flow reversal, the delimitation of flow - recirculation zones, and the determination of wall shear stress response to moving bubbles. Other applications of these sensors in microfluidics (e.g. characterization of liquid films, capillary waves, bubbles or drops) can be also envisaged.

  1. A pneumatic pressure-driven multi-throughput microfluidic circulation culture system.

    PubMed

    Satoh, T; Narazaki, G; Sugita, R; Kobayashi, H; Sugiura, S; Kanamori, T

    2016-06-21

    Here, we report a pneumatic pressure-driven microfluidic device capable of multi-throughput medium circulation culture. The circulation culture system has the following advantages for application in drug discovery: (i) simultaneous operation of multiple circulation units, (ii) use of a small amount of circulating medium (3.5 mL), (iii) pipette-friendly liquid handling, and (iv) a detachable interface with pneumatic pressure lines via sterile air-vent filters. The microfluidic device contains three independent circulation culture units, in which human umbilical vein endothelial cells (HUVECs) were cultured under physiological shear stress induced by circulation of the medium. Circulation of the medium in the three culture units was generated by programmed sequentially applied pressure from two pressure-control lines. HUVECs cultured in the microfluidic device were aligned under a one-way circulating flow with a shear stress of 10 dyn cm(-2); they exhibited a randomly ordered alignment under no shear stress and under reciprocating flow with a shear stress of 10 dyn cm(-2). We also observed 2.8- to 4.9-fold increases in expression of the mRNAs of endothelial nitric oxide synthase and thrombomodulin under one-way circulating flow with a shear stress of 10 dyn cm(-2) compared with conditions of no shear stress or reciprocating flow.

  2. Smart hydrogels as storage elements with dispensing functionality in discontinuous microfluidic systems.

    PubMed

    Haefner, Sebastian; Frank, Philipp; Elstner, Martin; Nowak, Johannes; Odenbach, Stefan; Richter, Andreas

    2016-10-05

    Smart hydrogels are useful elements in microfluidic systems because they respond to environmental stimuli and are capable of storing reagents. We present here a concept of using hydrogels (poly(N-isopropylacrylamide)) as an interface between continuous and discontinuous microfluidics. Their swelling and shrinking capabilities allow them to act as storage elements for reagents absorbed in the swelling process. When the swollen hydrogel collapses in an oil-filled channel, the incorporated water and molecules are expelled from the hydrogel and form a water reservoir. Water-in-oil droplets can be released from the reservoir generating different sized droplets depending on the flow regime at various oil flow rates (dispensing functionality). Different hydrogel sizes and microfluidic structures are discussed in terms of their storage and droplet formation capabilities. The time behaviour of the hydrogel element is investigated by dynamic swelling experiments and computational fluid dynamics simulations. By precise temperature control, the device acts as an active droplet generator and converts continuous to discontinuous flows.

  3. Novel localized heating technique on centrifugal microfluidic disc with wireless temperature monitoring system.

    PubMed

    Joseph, Karunan; Ibrahim, Fatimah; Cho, Jongman

    2015-01-01

    Recent advances in the field of centrifugal microfluidic disc suggest the need for electrical interface in the disc to perform active biomedical assays. In this paper, we have demonstrated an active application powered by the energy harvested from the rotation of the centrifugal microfluidic disc. A novel integration of power harvester disc onto centrifugal microfluidic disc to perform localized heating technique is the main idea of our paper. The power harvester disc utilizing electromagnetic induction mechanism generates electrical energy from the rotation of the disc. This contributes to the heat generation by the embedded heater on the localized heating disc. The main characteristic observed in our experiment is the heating pattern in relative to the rotation of the disc. The heating pattern is monitored wirelessly with a digital temperature sensing system also embedded on the disc. Maximum temperature achieved is 82 °C at rotational speed of 2000 RPM. The technique proves to be effective for continuous heating without the need to stop the centrifugal motion of the disc.

  4. The effect of nifedipine on myocardial perfusion and metabolism in systemic sclerosis. A positron emission tomographic study

    SciTech Connect

    Duboc, D.; Kahan, A.; Maziere, B.; Loc'h, C.; Crouzel, C.; Menkes, C.J.; Amor, B.; Strauch, G.; Guerin, F.; Syrota, A. )

    1991-02-01

    We assessed the effect of nifedipine on myocardial perfusion and metabolism in 9 patients with systemic sclerosis, using positron emission tomography with a perfusion tracer (potassium-38) and a metabolic tracer (18F-fluorodeoxyglucose (18FDG)). Nifedipine, 20 mg 3 times daily for 1 week, induced a significant increase in 38K myocardial uptake, a significant decrease in 18FDG myocardial uptake, and a significant increase in the myocardial 38K: 18FDG ratio. These results indicate that the increase in myocardial perfusion is associated with modifications in myocardial energy metabolism, which probably result from a beneficial anti-ischemic effect of nifedipine in patients with systemic sclerosis.

  5. An integrated microfluidics-tandem mass spectrometry system for automated protein analysis.

    PubMed

    Figeys, D; Gygi, S P; McKinnon, G; Aebersold, R

    1998-09-15

    We describe an integrated analytical system consisting of a microfluidics device micromachined using photolithography/etching technology, a panel of computer-controlled high-voltage relays, and an electrospray ionization tandem mass spectrometer. Movement of solvents and samples on the device and off the device to the mass spectrometer was achieved by directed electroosmotic pumping induced by the activation of a suitable constellation of high-voltage relays. The system was used for the sequential automated analysis of protein digests. We demonstrate low femtomole per microliter sensitivity of detection and compatibility of the system with the automated analysis of proteins separated by two-dimensional gel electrophoresis.

  6. Comparative Single-Cell Analysis of Different E. coli Expression Systems during Microfluidic Cultivation

    PubMed Central

    Hilgers, Fabienne; Loeschcke, Anita; Jaeger, Karl-Erich; Kohlheyer, Dietrich; Drepper, Thomas

    2016-01-01

    Recombinant protein production is mostly realized with large-scale cultivations and monitored at the level of the entire population. Detailed knowledge of cell-to-cell variations with respect to cellular growth and product formation is limited, even though phenotypic heterogeneity may distinctly hamper overall production yields, especially for toxic or difficult-to-express proteins. Unraveling phenotypic heterogeneity is thus a key aspect in understanding and optimizing recombinant protein production in biotechnology and synthetic biology. Here, microfluidic single-cell analysis serves as the method of choice to investigate and unmask population heterogeneities in a dynamic and spatiotemporal fashion. In this study, we report on comparative microfluidic single-cell analyses of commonly used E. coli expression systems to uncover system-inherent specifications in the synthetic M9CA growth medium. To this end, the PT7lac/LacI, the PBAD/AraC and the Pm/XylS system were systematically analyzed in order to gain detailed insights into variations of growth behavior and expression phenotypes and thus to uncover individual strengths and deficiencies at the single-cell level. Specifically, we evaluated the impact of different system-specific inducers, inducer concentrations as well as genetic modifications that affect inducer-uptake and regulation of target gene expression on responsiveness and phenotypic heterogeneity. Interestingly, the most frequently applied expression system based on E. coli strain BL21(DE3) clearly fell behind with respect to expression homogeneity and robustness of growth. Moreover, both the choice of inducer and the presence of inducer uptake systems proved crucial for phenotypic heterogeneity. Conclusively, microfluidic evaluation of different inducible E. coli expression systems and setups identified the modified lacY-deficient PT7lac/LacI as well as the Pm/XylS system with conventional m-toluic acid induction as key players for precise and robust

  7. Cardiopulmonary bypass with a surface-heparinized extracorporeal perfusion system.

    PubMed

    Palatianos, G M; Dewanjee, M K; Kapadvanjwala, M; Novak, S; Sfakianakis, G N; Kaiser, G A

    1990-01-01

    To evaluate the effect of surface heparinization on platelet consumption during cardiopulmonary bypass (CPB) ten pigs were placed on CPB for 3 hours. All pigs were injected with autologous Indium-111 labeled platelets (300-420 uCi) 24 hours prior to CPB and were systemically heparinized prior to cannulation for CPB. CPB was established with a roller pump, a hollow fiber membrane oxygenator (HFMO, Bentley CM-50) and an arterial filter (AF, Bentley 1025). In six pigs the extracorporeal system was untreated whereas in four pigs it was surface heparinized with the Duraflo-II method. Cardiotomy suction was not used. Percent of injected radiation dose in HFMO and AF at 3 hours of CPB in the nontreated systems was 1.53 +/- 1.12 and 0.88 +/- 0.63%, whereas in the surface heparinized systems was 2.45 +/- 1.71 and 0.49 +/- 0.39% respectively (NS). (Values are mean +/- SD). Blood loss during (CPB) was 225 +/- 179 ml in the nontreated systems, and 263 +/- 103 ml in the surface heparinized systems (NS). Platelet counts were reduced by 12% or 21.8% at 3 hours of CPB in the two groups of pigs respectively (NS). No difference was observed in platelet consumption (in HFMO and in AF) or in platelet count reduction between the two groups of pigs. Surface heparinization did not improve platelet preservation in systemically heparinized pigs at 3 hours of CPB.

  8. 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.

  9. Supportive development of functional tissues for biomedical research using the MINUSHEET® perfusion system

    PubMed Central

    2012-01-01

    Functional tissues generated under in vitro conditions are urgently needed in biomedical research. However, the engineering of tissues is rather difficult, since their development is influenced by numerous parameters. In consequence, a versatile culture system was developed to respond the unmet needs. Optimal adhesion for cells in this system is reached by the selection of individual biomaterials. To protect cells during handling and culture, the biomaterial is mounted onto a MINUSHEET® tissue carrier. While adherence of cells takes place in the static environment of a 24 well culture plate, generation of tissues is accomplished in one of several available perfusion culture containers. In the basic version a continuous flow of always fresh culture medium is provided to the developing tissue. In a gradient perfusion culture container epithelia are exposed to different fluids at the luminal and basal sides. Another special container with a transparent lid and base enables microscopic visualization of ongoing tissue development. A further container exhibits a flexible silicone lid to apply force onto the developing tissue thereby mimicking mechanical load that is required for developing connective and muscular tissue. Finally, stem/progenitor cells are kept at the interface of an artificial polyester interstitium within a perfusion culture container offering for example an optimal environment for the spatial development of renal tubules. The system presented here was evaluated by various research groups. As a result a variety of publications including most interesting applications were published. In the present paper these data were reviewed and analyzed. All of the results point out that the cell biological profile of engineered tissues can be strongly improved, when the introduced perfusion culture technique is applied in combination with specific biomaterials supporting primary adhesion of cells. PMID:23369669

  10. Versatile minimized system--a step towards safe perfusion.

    PubMed

    Ganushchak, Y M; Körver, E P J; Yamamoto, Y; Weerwind, P W

    2016-05-01

    A growing body of evidence indicates the superiority of minimized cardiopulmonary bypass (CPB) systems compared to conventional systems in terms of inflammatory reactions and transfusion requirements. Evident benefits of minimized CPB systems, however, do not come without consequences. Kinetic-assisted drainage, as used in these circuits, can result in severe fluctuations of venous line pressures and, consequently, fluctuation of the blood flow delivered to the patient. Furthermore, subatmospheric venous line pressures can cause gaseous microemboli. Another limitation is the absence of cardiotomy suction, which can lead to excessive blood loss via a cell saver. The most serious limitation of minimized circuits is that these circuits are very constrained in the case of complications or changing of the surgery plan. We developed a versatile minimized system (VMS) with a priming volume of about 600 ml. A compliance chamber in the venous line decreases peaks of pressure fluctuations. This chamber also acts as a bubble trap. Additionally, the open venous reservoir is connected parallel to the venous line and excluded from the circulation during an uncomplicated CPB. This reservoir can be included in the circulation via a roller pump and be used as a cardiotomy reservoir. The amount and rate of returned blood in the circulation is regulated by a movable level detector. Further, the circuit can easily be converted to an open system with vacuum-assisted venous drainage in the case of unexpected complications. The VMS combines the benefits of minimized circuits with the versatility and safety of a conventional CPB system. Perfusionists familiar with this system can secure an adequate and timely response at expected and unexpected intraoperative complications.

  11. 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.

  12. Novel microfluidic system for online monitoring of biofilm dynamics by electrical impedance spectroscopy and amperometry

    NASA Astrophysics Data System (ADS)

    Bruchmann, Julia; Sachsenheimer, Kai; Schwartz, Thomas; Rapp, Bastian E.

    2016-03-01

    Biofilm formation is ubiquitous in nature where microorganisms attach to surfaces and form highly adapted and protected communities. In technical and industrial systems like drinking water supply, food production or shipping industry biofilms are a major cause of product contamination, biofouling, and biocorrosion. Therefore, understanding of biofilm formation and means of preventing biofilm formation is important to develop novel biofilm treatment strategies. A system allowing directly online detection and monitoring biofilm formation is necessary. However, until today, there are little to none technical systems featuring a non-destructive real-time characterization of biofilm formation in a highthroughput manner. This paper presents such a microfluidic system based on electrical impedance spectroscopy (EIS) and amperomertic current measurement. The sensor consists of four modules, each housing 24 independent electrodes within 12 microfluidic channels. Attached biomass on the electrodes is monitored as increased inhibition in charge transfer by EIS and a change in metabolic activity is measured as change in produced electric current by amperometry. This modular sensor system is highly adaptable and suitable for a broad range of microbiological applications. Among others, biofilm formation processes can be characterized online, biofilm manipulation like inactivation or destabilization can be monitored in real-time and gene expression can be analyzed in parallel. The use of different electrode designs allows effective biofilm studies during all biofilm phases. The whole system was recently extended by an integrated pneumatic microfluidic pump which enables easy handling procedures. Further developments of this pumping module will allow a fully- automated computer-controlled valving and pumping.

  13. Multimodal tissue perfusion imaging using multi-spectral and thermographic imaging systems applied on clinical data

    NASA Astrophysics Data System (ADS)

    Klaessens, John H. G. M.; Nelisse, Martin; Verdaasdonk, Rudolf M.; Noordmans, Herke Jan

    2013-03-01

    Clinical interventions can cause changes in tissue perfusion, oxygenation or temperature. Real-time imaging of these phenomena could be useful for surgical strategy or understanding of physiological regulation mechanisms. Two noncontact imaging techniques were applied for imaging of large tissue areas: LED based multispectral imaging (MSI, 17 different wavelengths 370 nm-880 nm) and thermal imaging (7.5 to 13.5 μm). Oxygenation concentration changes were calculated using different analyzing methods. The advantages of these methods are presented for stationary and dynamic applications. Concentration calculations of chromophores in tissue require right choices of wavelengths The effects of different wavelength choices for hemoglobin concentration calculations were studied in laboratory conditions and consequently applied in clinical studies. Corrections for interferences during the clinical registrations (ambient light fluctuations, tissue movements) were performed. The wavelength dependency of the algorithms were studied and wavelength sets with the best results will be presented. The multispectral and thermal imaging systems were applied during clinical intervention studies: reperfusion of tissue flap transplantation (ENT), effectiveness of local anesthetic block and during open brain surgery in patients with epileptic seizures. The LED multispectral imaging system successfully imaged the perfusion and oxygenation changes during clinical interventions. The thermal images show local heat distributions over tissue areas as a result of changes in tissue perfusion. Multispectral imaging and thermal imaging provide complementary information and are promising techniques for real-time diagnostics of physiological processes in medicine.

  14. Changes in hemostasis during pediatric heart surgery: impact of a biocompatible heparin-coated perfusion system.

    PubMed

    Jensen, Eva; Andréasson, Svenerik; Bengtsson, Anders; Berggren, Håkan; Ekroth, Rolf; Larsson, Lars E; Ouchterlony, John

    2004-03-01

    This study describes the response in hemostasis during open-heart surgery with cardiopulmonary bypass (CPB) in children (<== 10 kg) and tests the hypothesis that the use of a biocompatible perfusion system, in comparison with a conventional system, causes less hemostatic activation. Prospective, randomized, controlled clinical study. Forty consecutive children <== 10 kg were included and divided into two groups: group bioc. (n = 19) treated with a fully heparin-coated system, centrifugal pump, and a closed circuit, and group conv. (n = 21) treated with an uncoated system, roller pump, and a hard shell venous reservoir. Concentrations of plasma thrombin-antithrombin (TAT), D-dimer, tissue plasminogen activator antigen (t-PA ag), and the complex consisting of tissue plasminogen activator and its inhibitor plasminogen activator inhibitor-1 (t-PA-PAI-1) were measured. The biochemical variables measured increased significantly in both groups during the study period. There was less activation of fibrinolysis during cardiopulmonary bypass (t-PA ag: p = 0.009) in patients treated with the biocompatible perfusion system than in patients treated with the conventional system. A trend in favor of the biocompatible system based on the D-dimer and TAT data (p = 0.07 for both measurements) was observed but no significant intergroup differences regarding these variables or t-PA-PAI-1 were found. Open-heart surgery with cardiopulmonary bypass in children (<== 10 kg) causes transient activation of the coagulation and fibrinolytic systems. This study demonstrates that the use of a biocompatible perfusion system results in a lower extent of activation of fibrinolysis during CPB than the use of a conventional system.

  15. A passive microfluidic fragmentation system for continuous fluid-particles separation

    NASA Astrophysics Data System (ADS)

    Viana, A.; Marchalot, J.; Fouillet, Y.; Digianantonio, L.; Claustre, P.; Cubizolles, M.; Achard, JL.

    2013-05-01

    We present herein a microfluidic system based on passive effects for continuously separate a diphasic fluid-particles flow. Initially developed as a portable blood fragmentation device, its ability to operate passively, on several kinds of objects - organic or inorganic - opens the way to environmental applications, such as water cleaning or analysis. This technology can be implemented as a SamplePrep system, first step of an on-site analysis protocol. In addition, its low-cost and reliable manufacturing, compact size, low weight and ease of use make this technology a possible support for the deployment of health policies in developing countries.

  16. Plant-in-chip: Microfluidic system for studying root growth and pathogenic interactions in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Parashar, Archana; Pandey, Santosh

    2011-06-01

    We report a microfluidic platform for the hydroponic growth of Arabidopsis plants with high-resolution visualization of root development and root-pathogen interactions. The platform comprises a set of parallel microchannels with individual input/output ports where 1-day old germinated seedlings are initially placed. Under optimum conditions, a root system grows in each microchannel and its images are recorded over a 198-h period. Different concentrations of plant growth media show different root growth characteristics. Later, the developed roots are inoculated with two plant pathogens (nematodes and zoospores) and their physicochemical interactions with the live root systems are observed.

  17. Automated and miniaturized detection of biological threats with a centrifugal microfluidic system

    NASA Astrophysics Data System (ADS)

    Mark, D.; van Oordt, T.; Strohmeier, O.; Roth, G.; Drexler, J.; Eberhard, M.; Niedrig, M.; Patel, P.; Zgaga-Griesz, A.; Bessler, W.; Weidmann, M.; Hufert, F.; Zengerle, R.; von Stetten, F.

    2012-06-01

    The world's growing mobility, mass tourism, and the threat of terrorism increase the risk of the fast spread of infectious microorganisms and toxins. Today's procedures for pathogen detection involve complex stationary devices, and are often too time consuming for a rapid and effective response. Therefore a robust and mobile diagnostic system is required. We present a microstructured LabDisk which performs complex biochemical analyses together with a mobile centrifugal microfluidic device which processes the LabDisk. This portable system will allow fully automated and rapid detection of biological threats at the point-of-need.

  18. 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

  19. A hybrid microfluidic-vacuum device for direct interfacing with conventional cell culture methods

    PubMed Central

    Chung, Bong Geun; Park, Jeong Won; Hu, Jia Sheng; Huang, Carlos; Monuki, Edwin S; Jeon, Noo Li

    2007-01-01

    Background Microfluidics is an enabling technology with a number of advantages over traditional tissue culture methods when precise control of cellular microenvironment is required. However, there are a number of practical and technical limitations that impede wider implementation in routine biomedical research. Specialized equipment and protocols required for fabrication and setting up microfluidic experiments present hurdles for routine use by most biology laboratories. Results We have developed and validated a novel microfluidic device that can directly interface with conventional tissue culture methods to generate and maintain controlled soluble environments in a Petri dish. It incorporates separate sets of fluidic channels and vacuum networks on a single device that allows reversible application of microfluidic gradients onto wet cell culture surfaces. Stable, precise concentration gradients of soluble factors were generated using simple microfluidic channels that were attached to a perfusion system. We successfully demonstrated real-time optical live/dead cell imaging of neural stem cells exposed to a hydrogen peroxide gradient and chemotaxis of metastatic breast cancer cells in a growth factor gradient. Conclusion This paper describes the design and application of a versatile microfluidic device that can directly interface with conventional cell culture methods. This platform provides a simple yet versatile tool for incorporating the advantages of a microfluidic approach to biological assays without changing established tissue culture protocols. PMID:17883868

  20. A hybrid microfluidic-vacuum device for direct interfacing with conventional cell culture methods.

    PubMed

    Chung, Bong Geun; Park, Jeong Won; Hu, Jia Sheng; Huang, Carlos; Monuki, Edwin S; Jeon, Noo Li

    2007-09-20

    Microfluidics is an enabling technology with a number of advantages over traditional tissue culture methods when precise control of cellular microenvironment is required. However, there are a number of practical and technical limitations that impede wider implementation in routine biomedical research. Specialized equipment and protocols required for fabrication and setting up microfluidic experiments present hurdles for routine use by most biology laboratories. We have developed and validated a novel microfluidic device that can directly interface with conventional tissue culture methods to generate and maintain controlled soluble environments in a Petri dish. It incorporates separate sets of fluidic channels and vacuum networks on a single device that allows reversible application of microfluidic gradients onto wet cell culture surfaces. Stable, precise concentration gradients of soluble factors were generated using simple microfluidic channels that were attached to a perfusion system. We successfully demonstrated real-time optical live/dead cell imaging of neural stem cells exposed to a hydrogen peroxide gradient and chemotaxis of metastatic breast cancer cells in a growth factor gradient. This paper describes the design and application of a versatile microfluidic device that can directly interface with conventional cell culture methods. This platform provides a simple yet versatile tool for incorporating the advantages of a microfluidic approach to biological assays without changing established tissue culture protocols.

  1. A compact disk-like centrifugal microfluidic system for high-throughput nanoliter-scale protein crystallization screening.

    PubMed

    Li, Gang; Chen, Qiang; Li, Junjun; Hu, Xiaojian; Zhao, Jianlong

    2010-06-01

    A centrifuge-based microfluidic system has been developed that enables automated high-throughput and low-volume protein crystallizations. In this system, protein solution was automatically and accurately metered and dispensed into nanoliter-sized multiple reaction chambers, and it was mixed with various types of precipitants using a combination of capillary effect and centrifugal force. It has the advantages of simple fabrication, easy operation, and extremely low waste. To demonstrate the feasibility of this system, we constructed a chip containing 24 units and used it to perform lysozyme and cyan fluorescent protein (CyPet) crystallization trials. The results demonstrate that high-quality crystals can be grown and harvested from such a nanoliter-volume microfluidic system. Compared to other microfluidic technologies for protein crystallization, this microfluidic system allows zero waste, simple structure and convenient operation, which suggests that our microfluidic disk can be applied not only to protein crystallization, but also to the miniaturization of various biochemical reactions requiring precise nanoscale control.

  2. Note: A micro-perfusion system for use during real-time physiological studies under high pressure.

    PubMed

    Maltas, Jeff; Long, Zac; Huff, Alison; Maloney, Ryan; Ryan, Jordan; Urayama, Paul

    2014-10-01

    We construct a micro-perfusion system using piston screw pump generators for use during real-time, high-pressure physiological studies. Perfusion is achieved using two generators, with one generator being compressed while the other is retracted, thus maintaining pressurization while producing fluid flow. We demonstrate control over perfusion rates in the 10-μl/s range and the ability to change between fluid reservoirs at up to 50 MPa. We validate the screw-pump approach by monitoring the cyanide-induced response of UV-excited autofluorescence from Saccharomyces cerevisiae under pressurization.

  3. Note: A micro-perfusion system for use during real-time physiological studies under high pressure

    NASA Astrophysics Data System (ADS)

    Maltas, Jeff; Long, Zac; Huff, Alison; Maloney, Ryan; Ryan, Jordan; Urayama, Paul

    2014-10-01

    We construct a micro-perfusion system using piston screw pump generators for use during real-time, high-pressure physiological studies. Perfusion is achieved using two generators, with one generator being compressed while the other is retracted, thus maintaining pressurization while producing fluid flow. We demonstrate control over perfusion rates in the 10-μl/s range and the ability to change between fluid reservoirs at up to 50 MPa. We validate the screw-pump approach by monitoring the cyanide-induced response of UV-excited autofluorescence from Saccharomyces cerevisiae under pressurization.

  4. Design and evaluation of a microfluidic system for inhibition studies of yeast cell signaling

    NASA Astrophysics Data System (ADS)

    Hamngren, Charlotte; Dinér, Peter; Grøtli, Morten; Goksör, Mattias; Adiels, Caroline B.

    2012-10-01

    In cell signaling, different perturbations lead to different responses and using traditional biological techniques that result in averaged data may obscure important cell-to-cell variations. The aim of this study was to develop and evaluate a four-inlet microfluidic system that enables single-cell analysis by investigating the effect on Hog1 localization post a selective Hog1 inhibitor treatment during osmotic stress. Optical tweezers was used to position yeast cells in an array of desired size and density inside the microfluidic system. By changing the flow rates through the inlet channels, controlled and rapid introduction of two different perturbations over the cell array was enabled. The placement of the cells was determined by diffusion rates flow simulations. The system was evaluated by monitoring the subcellular localization of a fluorescently tagged kinase of the yeast "High Osmolarity Glycerol" (HOG) pathway, Hog1-GFP. By sequential treatment of the yeast cells with a selective Hog1 kinase inhibitor and sorbitol, the subcellular localization of Hog1-GFP was analysed on a single-cell level. The results showed impaired Hog1-GFP nuclear localization, providing evidence of a congenial design. The setup made it possible to remove and add an agent within 2 seconds, which is valuable for investigating the dynamic signal transduction pathways and cannot be done using traditional methods. We are confident that the features of the four-inlet microfluidic system will be a valuable tool and hence contribute significantly to unravel the mechanisms of the HOG pathway and similar dynamic signal transduction pathways.

  5. 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

  6. An integrated fluorescence detection system in poly(dimethylsiloxane) for microfluidic applications.

    PubMed

    Chabinyc, M L; Chiu, D T; McDonald, J C; Stroock, A D; Christian, J F; Karger, A M; Whitesides, G M

    2001-09-15

    This paper describes a prototype of an integrated fluorescence detection system that uses a microavalanche photodiode (microAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The prototype device consisted of a reusable detection system and a disposable microfluidic system that was fabricated using rapid prototyping. The first step of the procedure was the fabrication of microfluidic channels in PDMS and the encapsulation of a multimode optical fiber (100-microm core diameter) in the PDMS; the tip of the fiber was placed next to the side wall of one of the channels. The optical fiber was used to couple light into the microchannel for the excitation of fluorescent analytes. The photodetector, a prototype solid-state microAPD array, was embedded in a thick slab (1 cm) of PDMS. A thin (80 microm) colored polycarbonate filter was placed on the top of the embedded microAPD to absorb scattered excitation light before it reached the detector. The microAPD was placed below the microchannel and orthogonal to the axis of the optical fiber. The close proximity (approximately 200 microm) of the microAPD to the microchannel made it unnecessary to incorporate transfer optics; the pixel size of the microAPD (30 microm) matched the dimensions of the channels (50 microm). A blue light-emitting diode was used for fluorescence excitation. The microAPD was operated in Geiger mode to detect the fluorescence. The detection limit of the prototype (approximately 25 nM) was determined by finding the minimum detectable concentration of a solution of fluorescein. The device was used to detect the separation of a mixture of proteins and small molecules by capillary electrophoresis; the separation illustrated the suitability of this integrated fluorescence detection system for bioanalytical applications.

  7. Recent Results of the Investigation of a Microfluidic Sampling Chip and Sampling System for Hot Cell Aqueous Processing Streams

    SciTech Connect

    Julia Tripp; Jack Law; Tara Smith

    2013-10-01

    A Fuel Cycle Research and Development project has investigated an innovative sampling method that could evolve into the next generation sampling and analysis system for metallic elements present in aqueous processing streams. Initially sampling technologies were evaluated and microfluidics sampling chip technology was selected and tested. A conceptual design for a fully automated microcapillary-based system was completed and a robotic automated sampling system was fabricated. The mechanical and sampling operation of the completed sampling system was investigated. In addition, the production of a less expensive, mass produced sampling chip was investigated to avoid chip reuse thus increasing sampling reproducibility/accuracy. The microfluidic-based robotic sampling system’s mechanical elements were tested to ensure analytical reproducibility and the optimum robotic handling of microfluidic sampling chips.

  8. Pharmacodynamic effect of dipyridamole on thallium-201 myocardial perfusion in progressive systemic sclerosis with diffuse scleroderma.

    PubMed Central

    Kahan, A; Devaux, J Y; Amor, B; Menkes, C J; Weber, S; Foult, J M; Venot, A; Guerin, F; Degeorges, M; Roucayrol, J C

    1986-01-01

    We evaluated the effect of dipyridamole on thallium-201 myocardial perfusion in 23 patients with progressive systemic sclerosis (PSS) with diffuse scleroderma. Thallium-201 single photon emission computed tomography (SPECT) was performed at rest and after coronary artery vasodilatation with intravenous dipyridamole (0.14 mg/kg/min for four minutes). The left myocardium was divided into nine segments; each segment was graded as 2.0, 1.5, 1.0, 0.5, 0 (zero represents no activity). Dipyridamole significantly improved resting thallium-201 myocardial perfusion: the mean (SD) number of segments with thallium defects decreased from 6.0 (2.1) at rest to 4.1 (2.5) after dipyridamole (p less than 0.0001); the mean (SD) score in segments with resting defects increased from 0.92 (0.24) at rest to 1.13 (0.38) after dipyridamole (p less than 0.0001); the mean (SD) global score per patient increased from 10.2 (1.8) at rest to 11.4 (2.1) after dipyridamole (p less than 0.02); the global score increased by at least 2.0 in 12 patients and worsened by at least 2.0 in three patients only (p = 0.05). The results of this acute study suggest that some drugs with potent vasodilator activity on small coronary arteries may be beneficial in the treatment of PSS patients with thallium-201 myocardial perfusion abnormalities. Images PMID:3490227

  9. Reliability of myocardial perfusion quantification in angiography using a digital flat panel cardiac system

    NASA Astrophysics Data System (ADS)

    Perrin, Muriel; Vaillant, Regis; Gavit-Houdant, Laurence; Lienard, Jean; Benali, Karim

    2002-04-01

    Discordance between lesion severity from angiocardiography and physiological effects has been reported elsewhere. Quantification of myocardial perfusion during the angiography procedure may supply additional information about short- and long-term outcomes and may be helpful for clinical decision making. In previous works, myocardial perfusion has been assessed using time density curves (TDC), which represent the contrast medium dilution over time in the myocardium. The mean transit time (MTT), derived from the TDC, has been reported as a good indicator of the regional myocardial perfusion. Our objective is to estimate the accuracy and reproducibility of MTT estimation on digital flat panel (DFP) images. We have simulated typical myocardium TDC obtained with a DFP cardiac system (Innova 2000, GE), taking into account scatter and noise. Logarithmic or linear subtractions have been applied to derive a contrast medium concentration proportional quantity from image intensity. A non-linear minimisation realises the model curve fitting. MTT estimates are more stable with linear subtraction in presence of scatter. However logarithmic subtraction presents smaller bias when scatter level is small. Both approaches are equally sensible to image noise. Linear subtraction should be preferred. Image noise has a high influence on MTT accuracy and we may reduce.

  10. Longterm treatment with endothelin receptor antagonist bosentan and iloprost improves fingertip blood perfusion in systemic sclerosis.

    PubMed

    Cutolo, Maurizio; Ruaro, Barbara; Pizzorni, Carmen; Ravera, Francesca; Smith, Vanessa; Zampogna, Giuseppe; Paolino, Sabrina; Seriolo, Bruno; Cimmino, Marco; Sulli, Alberto

    2014-05-01

    To evaluate the longterm effects of endothelin-1 (ET-1) antagonism on peripheral blood perfusion (PBP) in patients with systemic sclerosis (SSc). Twenty-six patients with SSc already receiving cyclic intravenous iloprost (ILO) for severe Raynaud phenomenon were enrolled. Thirteen patients continued the treatment for a further 3 years (ILO group) and 13 patients, because of the appearance of digital ulcers, received in addition bosentan (BOS; 125 mg twice/day) for 3 years (ILO + BOS group). Both PBP at fingertips and nailfold microangiopathy were evaluated yearly by laser Doppler flowmetry and nailfold videocapillaroscopy, respectively. A progressive significant increase of PBP was observed in the ILO + BOS group during the 3 followup years (p = 0.0007, p = 0.0002, p = 0.01, respectively). In contrast, an insignificant progressive decrease of PBP was observed in the ILO group. Difference of perfusion between the PBP evaluations at basal temperature and at 36 °C (to test capillary dilation capacity), was found progressively decreased during the 3-year followup only in the ILO group (p = 0.05, p = 0.26, p = 0.09, respectively). A progressive increase of nailfold capillary number was observed only in the ILO + BOS group after 2 and 3 years of followup (p = 0.05). Longterm treatment of SSc patients with ET-1 antagonism, in combination with ILO, seems to increase fingertip blood perfusion, as well as both capillary dilation capacity and number.

  11. Manipulation of liquid-liquid interfaces for tunable optics on a chip in microfluidic systems

    NASA Astrophysics Data System (ADS)

    Tan, Kam Yan Sindy

    This thesis describes the design and development of optofluidics: a new class of optical components based on dynamic liquid-liquid interfaces between liquids possessing different optical properties in microfluidic systems. Devices with optical interfaces formed by liquids possess characteristics that are quite different from solid-gas and solid-liquid systems commonly used in conventional optics. Advantages of optofluidic systems include the simplicity to reconfigure optical properties and functions in real time. Examples of devices include liquid waveguides, lenses, and multi-color droplet dye laser. Potential applications include biochemical characterization and optical spectroscopy in micro-total analytical systems. Chapter 1 describers the motivation, general configuration and characteristics of devices with optical interfaces formed by liquids in microchannels. Chapter 2 describes the soft lithographic techniques used to make optofluidic devices. Chapter 3 describes the use of co-fabrication to design and fabricate multiple functional components in microfluidic systems in a single step. Chapters 4 to 6 describe the design and operation of three optofluidic devices: waveguides, lenses, and dye lasers.

  12. Bioprocess Control in Microscale: Scalable Fermentations in Disposable and User-Friendly Microfluidic Systems

    PubMed Central

    2010-01-01

    Background The efficiency of biotechnological production processes depends on selecting the best performing microbial strain and the optimal cultivation conditions. Thus, many experiments have to be conducted, which conflicts with the demand to speed up drug development processes. Consequently, there is a great need for high-throughput devices that allow rapid and reliable bioprocess development. This need is addressed, for example, by the fiber-optic online-monitoring system BioLector which utilizes the wells of shaken microtiter plates (MTPs) as small-scale fermenters. To further improve the application of MTPs as microbioreactors, in this paper, the BioLector technology is combined with microfluidic bioprocess control in MTPs. To realize a user-friendly system for routine laboratory work, disposable microfluidic MTPs are utilized which are actuated by a user-friendly pneumatic hardware. Results This novel microfermentation system was tested in pH-controlled batch as well as in fed-batch fermentations of Escherichia coli. The pH-value in the culture broth could be kept in a narrow dead band of 0.03 around the pH-setpoint, by pneumatically dosing ammonia solution and phosphoric acid to each culture well. Furthermore, fed-batch cultivations with linear and exponential feeding of 500 g/L glucose solution were conducted. Finally, the scale-up potential of the microscale fermentations was evaluated by comparing the obtained results to that of fully controlled fermentations in a 2 L laboratory-scale fermenter (working volume of 1 L). The scale-up was realized by keeping the volumetric mass transfer coefficient kLa constant at a value of 460 1/h. The same growth behavior of the E. coli cultures could be observed on both scales. Conclusion In microfluidic MTPs, pH-controlled batch as well as fed-batch fermentations were successfully performed. The liquid dosing as well as the biomass growth kinetics of the process-controlled fermentations agreed well both in the

  13. Numerical analysis of mixing by electrothermal induced flow in microfluidic systems

    PubMed Central

    Feng, J. J.; Krishnamoorthy, S.; Sundaram, S.

    2007-01-01

    An electrothermal flow induced chaotic mixing in microfluidic systems is studied analytically and numerically. The flow is induced due to the Coulombic and dielectric forces arising from the variation of the dielectric properties with respect to the temperature in the presence of an electric field. The numerical model is validated using an analytical solution derived for basic flow patterns in a simplified geometry. The computational model has been used to illustrate the mixing in microcavity and T-sensor constructs. The simulations predict the chaotic nature of the mixing process, where the material interface evolution shows exponential growth. PMID:19693379

  14. Methods, microfluidic devices, and systems for detection of an active enzymatic agent

    SciTech Connect

    Sommer, Gregory J; Hatch, Anson V; Singh, Anup K; Wang, Ying-Chih

    2014-10-28

    Embodiments of the present invention provide methods, microfluidic devices, and systems for the detection of an active target agent in a fluid sample. A substrate molecule is used that contains a sequence which may cleave in the presence of an active target agent. A SNAP25 sequence is described, for example, that may be cleaved in the presence of Botulinum Neurotoxin. The substrate molecule includes a reporter moiety. The substrate molecule is exposed to the sample, and resulting reaction products separated using electrophoretic separation. The elution time of the reporter moiety may be utilized to identify the presence or absence of the active target agent.

  15. Robust fluidic connections to freestanding microfluidic hydrogels

    PubMed Central

    Baer, Bradly B.; Larsen, Taylor S. H.

    2015-01-01

    Biomimetic scaffolds approaching physiological scale, whose size and large cellular load far exceed the limits of diffusion, require incorporation of a fluidic means to achieve adequate nutrient/metabolite exchange. This need has driven the extension of microfluidic technologies into the area of biomaterials. While construction of perfusable scaffolds is essentially a problem of microfluidic device fabrication, functional implementation of free-standing, thick-tissue constructs depends upon successful integration of external pumping mechanisms through optimized connective assemblies. However, a critical analysis to identify optimal materials/assembly components for hydrogel substrates has received little focus to date. This investigation addresses this issue directly by evaluating the efficacy of a range of adhesive and mechanical fluidic connection methods to gelatin hydrogel constructs based upon both mechanical property analysis and cell compatibility. Results identify a novel bioadhesive, comprised of two enzymatically modified gelatin compounds, for connecting tubing to hydrogel constructs that is both structurally robust and non-cytotoxic. Furthermore, outcomes from this study provide clear evidence that fluidic interconnect success varies with substrate composition (specifically hydrogel versus polydimethylsiloxane), highlighting not only the importance of selecting the appropriately tailored components for fluidic hydrogel systems but also that of encouraging ongoing, targeted exploration of this issue. The optimization of such interconnect systems will ultimately promote exciting scientific and therapeutic developments provided by microfluidic, cell-laden scaffolds. PMID:26045731

  16. Sensing Characteristics of Shear-Mode AlN Solidly Mounted Resonators with a Silicone Microfluidic System in Viscous Media

    NASA Astrophysics Data System (ADS)

    Xiong, Juan; Guo, Peng; Sun, Xi-Liang; Wang, Sheng-Fu; Hu, Ming-Zhe; Gu, Hao-Shuang

    2014-02-01

    AlN solidly mounted resonators with silicone microfluidic systems vibrating in shear mode are fabricated and characterized. The fabrication process is compatible with integrated circuits and the c-axis tilted AlN films are deposited, which allow in-liquid operation through excitation of the shear mode. The silicone microfluidic system is mounted on top of the sensor chip to transport the analyses and confine the flow to the active area. The properties of sensor operation in air, deionized water, ethanol, isopropanol, 80% glycol aqueous solution, glycol, and olive oil are characterized. The effects of different viscosities on the resonance frequency shift and Q-factor of the sensor have been discussed. The sensitivity and Q value in glycol of the sensor are 1.52 MHz cm2/μg and around 60, respectively. The results indicate the potential of a highly sensitive microfluidic sensor system for the applications in viscous media.

  17. Configurations and control of magnetic fields for manipulating magnetic particles in microfluidic applications: magnet systems and manipulation mechanisms.

    PubMed

    Cao, Quanliang; Han, Xiaotao; Li, Liang

    2014-08-07

    The use of a magnetic field for manipulating the motion of magnetic particles in microchannels has attracted increasing attention in microfluidic applications. Generation of a flexible and controllable magnetic field plays a crucial role in making better use of the particle manipulation technology. Recent advances in the development of magnet systems and magnetic field control methods have shown that it has great potential for effective and accurate manipulation of particles in microfluidic systems. Starting with the analysis of magnetic forces acting on the particles, this review gives the configurations and evaluations of three main types of magnet system proposed in microfluidic applications. The interaction mechanisms of magnetic particles with magnetic fields are also discussed.

  18. Active 3-D microscaffold system with fluid perfusion for culturing in vitro neuronal networks.

    PubMed

    Rowe, Laura; Almasri, Mahmoud; Lee, Kil; Fogleman, Nick; Brewer, Gregory J; Nam, Yoonkey; Wheeler, Bruce C; Vukasinovic, Jelena; Glezer, Ari; Frazier, A Bruno

    2007-04-01

    This work demonstrated the design, fabrication, packaging, and characterization of an active microscaffold system with fluid perfusion/nutrient delivery functionalities for culturing in vitro neuronal networks from dissociated hippocampal rat pup neurons. The active microscaffold consisted of an 8 x 8 array of hollow, microfabricated, SU-8 towers (1.0 mm or 1.5 mm in height), with integrated, horizontal, SU-8 cross-members that connect adjacent towers, thus forming a 3-D grid that is conducive to branching, growth, and increased network formation of dissociated hippocampal neurons. Each microtower in the microscaffold system contained a hollow channel and multiple fluid ports for media delivery and perfusion of nutrients to the in vitro neuronal network growing within the microscaffold system. Additionally, there were two exposed Au electrodes on the outer wall of each microtower at varying heights (with insulated leads running within the microtower walls), which will later allow for integration of electrical stimulation/recording functionalities into the active microscaffold system. However, characterization of the stimulation/recording electrodes was not included in the scope of this paper. Design, fabrication, fluid packaging, and characterization of the active microscaffold system were performed. Furthermore, use of the active microscaffold system was demonstrated by culturing primary hippocampal embryonic rat pup neurons, and characterizing cell viability within the microscaffold system.

  19. Establishment of a gastric cancer subline with high metastatic potential using a novel microfluidic system

    PubMed Central

    Chen, Zhe-zhou; Li, Wan-ming; Zhang, Yu; Yu, Min; Shan, Lian-feng; Yuan, De-zheng; Liu, Fu-rong; Fang, Jin

    2016-01-01

    Metastasis is an important hallmark of malignant tumors. In this study, we developed a microfluidic system to screen highly metastatic sublines via differential resolution of cell invasiveness. The system was composed of a PDMS-glass device connected with a syringe pump and a Petri dish. To facilitate the selection process, a long-term cell invasion driving force based on a chemotactic factor gradient was created using the Petri dish-based liquid supply pattern, and the invasive cells were collected for round-by-round selection via an open region in the chip. Using the system, we established an SGC-7901/B2 subline from the human gastric cancer SGC-7901 cell line by only two rounds of selection. In vitro assays showed that the SGC-7901/B2 cells were superior to the parental cells in proliferation and invasiveness. Furthermore, an in vivo tumorigenicity assay demonstrated that compared with the parental cells, the subline had stronger spontaneous metastatic and proliferative capability, which led to a shorter survival duration. Additionally, the protein expression differences including E-cadherin and Smad3 between the subline and parental cells were revealed. In conclusion, this microfluidic system is a highly effective tool for selecting highly metastatic sublines, and SGC-7901/B2 cells could serve as a potential model for tumor metastasis research. PMID:27917905

  20. Study of Microfluidic System for Mechanical Property Measurement of Fluid-cell Interface

    NASA Astrophysics Data System (ADS)

    Moon, Ji Young; Lee, Jung Shin; Choi, Se Bin; Yoon, Hong Min; Tanner, Roger I.; Lee, Joon Sang

    2016-11-01

    The system for measuring the mechanical properties of active cell is studied through an integrated microfluidic system for cell separation, alignment and measurement of mechanical properties. A highly efficient lattice Boltzmann method (LBM) was employed to optimize the micro-fluidic system to investigate the interrelations between mechanical properties and various surrounding fluid ingredients which are difficult to observe using current experimental techniques. A combination model of the three dimensional LBM and the immersed boundary method (IBM) were used to simulate these systems. The LBM was used to determine incompressible fluid flow with a regular Eulerian grid. The IBM was used to solve the deformation of cells and matrix fluid interaction with a Lagrangian grid. Highly non-linear results such as cell-cell interactions, fluid-cell interactions, and optical force-cell interactions is studied. National Research Foundation of Korea (NRF) (Grant Number: NRF-2015R1A2A1A15056182, NRF-2015R1A5A1037668).

  1. DropBot: An open-source digital microfluidic control system with precise control of electrostatic driving force and instantaneous drop velocity measurement

    SciTech Connect

    Fobel, Ryan; Fobel, Christian; Wheeler, Aaron R.

    2013-05-13

    We introduce DropBot: an open-source instrument for digital microfluidics (http://microfluidics.utoronto.ca/dropbot). DropBot features two key functionalities for digital microfluidics: (1) real-time monitoring of instantaneous drop velocity (which we propose is a proxy for resistive forces), and (2) application of constant electrostatic driving forces through compensation for amplifier-loading and device capacitance. We anticipate that this system will enhance insight into failure modes and lead to new strategies for improved device reliability, and will be useful for the growing number of users who are adopting digital microfluidics for automated, miniaturized laboratory operation.

  2. A self-contained, programmable microfluidic cell culture system with real-time microscopy access.

    PubMed

    Skafte-Pedersen, Peder; Hemmingsen, Mette; Sabourin, David; Blaga, Felician Stefan; Bruus, Henrik; Dufva, Martin

    2012-04-01

    Utilizing microfluidics is a promising way for increasing the throughput and automation of cell biology research. We present a complete self-contained system for automated cell culture and experiments with real-time optical read-out. The system offers a high degree of user-friendliness, stability due to simple construction principles and compactness for integration with standard instruments. Furthermore, the self-contained system is highly portable enabling transfer between work stations such as laminar flow benches, incubators and microscopes. Accommodation of 24 individual inlet channels enables the system to perform parallel, programmable and multiconditional assays on a single chip. A modular approach provides system versatility and allows many different chips to be used dependent upon application. We validate the system's performance by demonstrating on-chip passive switching and mixing by peristaltically driven flows. Applicability for biological assays is demonstrated by on-chip cell culture including on-chip transfection and temporally programmable gene expression.

  3. Design and subspace system identification of an ex vivo vascular perfusion system.

    PubMed

    El-Kurdi, Mohammed S; Vipperman, Jeffrey S; Vorp, David A

    2009-04-01

    Numerical algorithms for subspace system identification (N4SID) are a powerful tool for generating the state space (SS) representation of any system. The purpose of this work was to use N4SID to generate SS models of the flowrate and pressure generation within an ex vivo vascular perfusion system (EVPS). Accurate SS models were generated and converted to transfer functions (TFs) to be used for proportional integral and derivative (PID) controller design. By prescribing the pressure and flowrate inputs to the pumping components within the EVPS and measuring the resulting pressure and flowrate in the system,_four TFs were estimated;_two for a flowrate controller (H(RP,f) and H(RPP,f)) and two for a pressure controller (H(RP,p) and H(RPP,p)). In each controller,_one TF represents a roller pump (H(RP,f) and H(RP,p)),_and the other represents a roller pump and piston in series (H(RPP,f) and H(RPP,p)). Experiments to generate the four TFs were repeated five times (N=5) from which average TFs were calculated. The average model fits, computed as the percentage of the output variation (to_the_prescribed_inputs) reproduced by the model, were 94.93+/-1.05% for H(RP,p), 81.29+/-0.20% for H(RPP,p), 94.45+/-0.73% for H(RP,f), and 77.12+/-0.36% for H(RPP,f). The simulated step, impulse, and frequency responses indicate that the EVPS is a stable system and can respond to signals containing power of up to 70_Hz.

  4. Microphysiological systems and low-cost microfluidic platform with analytics

    PubMed Central

    2013-01-01

    A multiorgan, functional, human in vitro assay system or 'Body-on-a-Chip' would be of tremendous benefit to the drug discovery and toxicology industries, as well as providing a more biologically accurate model for the study of disease as well as applied and basic biological research. Here, we describe the advances our team has made towards this goal, as well as the most pertinent issues facing further development of these systems. Description is given of individual organ models with appropriate cellular functionality, and our efforts to produce human iterations of each using primary and stem cell sources for eventual incorporation into this system. Advancement of the 'Body-on-a-Chip' field is predicated on the availability of abundant sources of human cells, capable of full differentiation and maturation to adult phenotypes, for which researchers are largely dependent on stem cells. Although this level of maturation is not yet achievable in all cell types, the work of our group highlights the high level of functionality that can be achieved using current technology, for a wide variety of cell types. As availability of functional human cell types for in vitro culture increases, the potential to produce a multiorgan in vitro system capable of accurately reproducing acute and chronic human responses to chemical and pathological challenge in real time will also increase. PMID:24565109

  5. High speed digital protein interaction analysis using microfluidic single molecule detection system.

    PubMed

    Chou, Chao-Kai; Jing, Nan; Yamaguchi, Hirohito; Tsou, Pei-Hsiang; Lee, Heng-Huan; Chen, Chun-Te; Wang, Ying-Nai; Hong, Sungmin; Su, Chin; Kameoka, Jun; Hung, Mien-Chie

    2010-07-21

    The understanding of protein interaction dynamics is important for signal transduction research but current available techniques prove difficult in addressing this issue. Thus, using the microfluidic approach, we developed a digital protein analytical platform and methodology named MAPS (Microfluidic system Analyzing Protein in Single complex) that can measure the amount of target proteins and protein complexes at the digitally single molecule resolution. By counting protein events individually, this system can provide rough protein interaction ratios which will be critical for understanding signal transduction dynamics. In addition, this system only requires less than an hour to characterize the target protein sample, which is much quicker than conventional approaches. As a proof of concept, we have determined the interaction ratios of oncogenic signaling protein complexes EGFR/Src and EGFR/STAT3 before and after EGF ligand stimulation. To the best of our knowledge, this is the first time that the interaction ratio between EGFR and its downstream proteins has been characterized. The information from MAPS will be critical for the study of protein signal transduction quantitation and dynamics.

  6. Fabrication of topologically complex three-dimensional microfluidic systems in PDMS by rapid prototyping.

    PubMed

    Anderson, J R; Chiu, D T; Jackman, R J; Cherniavskaya, O; McDonald, J C; Wu, H; Whitesides, S H; Whitesides, G M

    2000-07-15

    This paper describes a procedure for making topologically complex three-dimensional microfluidic channel systems in poly(dimethylsiloxane) (PDMS). This procedure is called the "membrane sandwich" method to suggest the structure of the final system: a thin membrane having channel structures molded on each face (and with connections between the faces) sandwiched between two thicker, flat slabs that provide structural support. Two "masters" are fabricated by rapid prototyping using two-level photolithography and replica molding. They are aligned face to face, under pressure, with PDMS prepolymer between them. The PDMS is cured thermally. The masters have complementary alignment tracks, so registration is straightforward. The resulting, thin PDMS membrane can be transferred and sealed to another membrane or slab of PDMS by a sequence of steps in which the two masters are removed one at a time; these steps take place without distortion of the features. This method can fabricate a membrane containing a channel that crosses over and under itself, but does not intersect itself and, therefore, can be fabricated in the form of any knot. It follows that this method can generate topologically complex microfluidic systems; this capability is demonstrated by the fabrication of a "basketweave" structure. By filling the channels and removing the membrane, complex microstructures can be made. Stacking and sealing more than one membrane allows even more complicated geometries than are possible in one membrane. A square coiled channel that surrounds, but does not connect to, a straight channel illustrates this type of complexity.

  7. Development of a fully integrated microfluidic system for sensing infectious viral disease.

    PubMed

    Huh, Yun Suk; Park, Tae Jung; Lee, Eun Zoo; Hong, Won Hi; Lee, Sang Yup

    2008-07-01

    An active micromixer system utilizing the magnetic force was developed and examined for its ability to facilitate the mixing of more than two fluid flows. The mixing performance of the active micromixer was evaluated in aqueous-aqueous systems including dyes for visual observation. A complete analytical microfluidic system was developed by integrating various functional modules into a single chip, thus allowing cell lysis, sample preparation, purification of intracellular molecules, and subsequent analysis. Upon loading the cell samples and lysis solution into the mixing chamber, the integrated microfluidic device allows efficient cell disruption by rotation of a micromagnetic disk and control of mixing time using the Teflon-coated hydrophobic film as a microvalve. This inflow is followed by separating the cell debris and contaminated proteins from the cell lysate sample using the acrylamide (AAm)-functionalized SPE. The inflow of partially purified cell lysate sample containing the gold binding polypeptide (GBP)-fusion protein was bound onto the gold micropatterns by means of its metal binding affinity. The GBP-fusion method allows immobilization of proteins in bioactive forms onto the gold surface without surface modification suitable for studying antigen-antibody interaction. It was used for the detection of severe acute respiratory syndrome (SARS), an infectious viral disease, as an example case.

  8. Rapid fabrication of a poly(dimethylsiloxane) microfluidic capillary gel electrophoresis system utilizing high precision machining.

    PubMed

    Zhao, Dong S; Roy, Binayak; McCormick, Matthew T; Kuhr, Werner G; Brazill, Sara A

    2003-05-01

    In this work, we demonstrate a rapid protocol to address one of the major barriers that exists in the fabrication of chip devices, creating the micron-sized structures in the substrate material. This approach makes it possible to design, produce, and fabricate a microfluidic system with channel features >10 microm in poly(dimethylsiloxane)(PDMS) in under 8 hours utilizing instrumentation common to most machine shops. The procedure involves the creation of a master template with negative features, using high precision machining. This master is then employed to create an acrylic mold that is used in the final fabrication step to cast channel structures into the PDMS substrate. The performance of the microfluidic system prepared using this fabrication procedure is evaluated by constructing a miniaturized capillary gel electrophoresis (micro-CGE) system for the analysis of DNA fragments. Agarose is utilized as the sieving medium in the micro-CGE device and is shown to give reproducible (RSD (n= 34) approximately 5.0%) results for about 34 individual separations without replenishing the gel. To demonstrate the functionality of the micro-CGE device, a DNA restriction ladder (spanning 26-700 base pairs) and DNA fragments generated by PCR are separated and detected with laser-induced fluorescence (LIF). The microchip is shown to achieve a separation efficiency of 2.53 x 10(5) plates m(-1).

  9. Numerical Modeling of Flow Distribution in Micro-Fluidics Systems

    NASA Technical Reports Server (NTRS)

    Majumdar, Alok; Cole, Helen; Chen, C. P.

    2005-01-01

    This paper describes an application of a general purpose computer program, GFSSP (Generalized Fluid System Simulation Program) for calculating flow distribution in a network of micro-channels. GFSSP employs a finite volume formulation of mass and momentum conservation equations in a network consisting of nodes and branches. Mass conservation equation is solved for pressures at the nodes while the momentum conservation equation is solved at the branches to calculate flowrate. The system of equations describing the fluid network is solved by a numerical method that is a combination of the Newton-Raphson and successive substitution methods. The numerical results have been compared with test data and detailed CFD (computational Fluid Dynamics) calculations. The agreement between test data and predictions is satisfactory. The discrepancies between the predictions and test data can be attributed to the frictional correlation which does not include the effect of surface tension or electro-kinetic effect.

  10. 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

  11. 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.

  12. Electroosmotic pumps and their applications in microfluidic systems

    PubMed Central

    Wang, Xiayan; Cheng, Chang; Wang, Shili; Liu, Shaorong

    2009-01-01

    Electroosmotic pumping is receiving increasing attention in recent years owing to the rapid development in micro total analytical systems. Compared with other micropumps, electroosmotic pumps (EOPs) offer a number of advantages such as creation of constant pulse-free flows and elimination of moving parts. The flow rates and pumping pressures of EOPs matches well with micro analysis systems. The common materials and fabrication technologies make it readily integrateable with lab-on-a-chip devices. This paper reviews the recent progress on EOP fabrications and applications in order to promote the awareness of EOPs to researchers interested in using micro- and nano-fluidic devices. The pros and cons of EOPs are also discussed, which helps these researchers in designing and constructing their micro platforms. PMID:20126306

  13. Subnormothermic Perfusion in the Isolated Rat Liver Preserves the Antioxidant Glutathione and Enhances the Function of the Ubiquitin Proteasome System

    PubMed Central

    Alva, Norma; Sanchez-Nuño, Sergio; Dewey, Shannamar; Gomes, Aldrin V.

    2016-01-01

    The reduction of oxidative stress is suggested to be one of the main mechanisms to explain the benefits of subnormothermic perfusion against ischemic liver damage. In this study we investigated the early cellular mechanisms induced in isolated rat livers after 15 min perfusion at temperatures ranging from normothermia (37°C) to subnormothermia (26°C and 22°C). Subnormothermic perfusion was found to maintain hepatic viability. Perfusion at 22°C raised reduced glutathione levels and the activity of glutathione reductase; however, lipid and protein oxidation still occurred as determined by malondialdehyde, 4-hydroxynonenal-protein adducts, and advanced oxidation protein products. In livers perfused at 22°C the lysosomal and ubiquitin proteasome system (UPS) were both activated. The 26S chymotrypsin-like (β5) proteasome activity was significantly increased in the 26°C (46%) and 22°C (42%) groups. The increased proteasome activity may be due to increased Rpt6 Ser120 phosphorylation, which is known to enhance 26S proteasome activity. Together, our results indicate that the early events produced by subnormothermic perfusion in the liver can induce oxidative stress concomitantly with antioxidant glutathione preservation and enhanced function of the lysosomal and UPS systems. Thus, a brief hypothermia could trigger antioxidant mechanisms and may be functioning as a preconditioning stimulus. PMID:27800122

  14. Magnetic manipulation of superparamagnetic nanoparticles in a microfluidic system for drug delivery applications

    NASA Astrophysics Data System (ADS)

    Agiotis, L.; Theodorakos, I.; Samothrakitis, S.; Papazoglou, S.; Zergioti, I.; Raptis, Y. S.

    2016-03-01

    Magnetic nanoparticles (MNPs), such as superparamagnetic iron oxide nanoparticles (SPIONS), have attracted major interest, due to their small size and unique magnetic properties, for drug delivery applications. In this context, iron oxide nanoparticles of magnetite (Fe3O4) (150 nm magnetic core diameter), were used as drug carriers, aiming to form a magnetically controlled nano-platform. The navigation capabilities of the iron oxide nanoparticles in a microfluidic channel were investigated by simulating the magnetic field and the magnetic force applied on the magnetic nanoparticles inside a microfluidic chip. The simulations have been performed using finite element method (ANSY'S software). The optimum setup which intends to simulate the magnetic navigation of the nanoparticles, by the use of MRI-type fields, in the human circulatory system, consists of two parallel permanent magnets to produce a homogeneous magnetic field, in order to ensure the maximum magnetization of the magnetic nanoparticles, an electromagnet for the induction of the magnetic gradients and the creation of the magnetic force and a microfluidic setup so as to simulate the blood flow inside the human blood vessels. The magnetization of the superparamagnetic nanoparticles and the consequent magnetic torque developed by the two permanent magnets, together with the mutual interactions between the magnetized nanoparticles lead to the creation of rhabdoid aggregates in the direction of the homogeneous field. Additionally, the magnetic gradients introduced by the operation of the electromagnet are capable of directing the aggregates, as a whole, to the desired direction. By removing the magnetic fields, the aggregates are disrupted, due to the super paramagnetic nature of the nanoparticles, avoiding thus the formation of undesired thrombosis.

  15. Impact of Nutrient Restriction on the Structure of Listeria monocytogenes Biofilm Grown in a Microfluidic System

    PubMed Central

    Cherifi, Tamazight; Jacques, Mario; Quessy, Sylvain; Fravalo, Philippe

    2017-01-01

    Biofilm formation by the pathogen Listeria monocytogenes is a major concern in food industries. The aim of this work was to elucidate the effect of nutrient limitation on both biofilm architecture and on the viability of the bacteria in microfluidic growth conditions. Biofilm formation by two L. monocytogenes strains was performed in a rich medium (BHI) and in a 10-fold diluted BHI (BHI/10) at 30°C for 24 h by using both static conditions and the microfluidic system Bioflux. In dynamic conditions, biofilms grown in rich and poor medium showed significant differences as well in structure and in the resulting biovolume. In BHI/10, biofilm was organized in a knitted network where cells formed long chains, whereas in the rich medium, the observed structure was homogeneous cellular multilayers. Biofilm biovolume production in BHI/10 was significantly higher than in BHI in these dynamic conditions. Interestingly, biovolume of dead cells in biofilms formed under limited nutrient conditions (BHI/10) was significantly higher than in biofilms formed in the BHI medium. In the other hand, in static conditions, biofilm is organized in a multilayer cells and dispersed cells in a rich medium BHI and poor medium BHI/10 respectively. There was significantly more biomass in the rich medium compared to BHI/10 but no difference was noted in the dead/damaged subpopulation showing how L. monocytogenes biofilm could be affected by the growth conditions. This work demonstrated that nutrient concentration affects biofilm structure and the proportion of dead cells in biofilms under microfluidic condition. Our study also showed that limited nutrients play an important role in the structural stability of L. monocytogenes biofilm by enhancing cell death and liberating extracellular DNA. PMID:28567031

  16. Impact of Nutrient Restriction on the Structure of Listeria monocytogenes Biofilm Grown in a Microfluidic System.

    PubMed

    Cherifi, Tamazight; Jacques, Mario; Quessy, Sylvain; Fravalo, Philippe

    2017-01-01

    Biofilm formation by the pathogen Listeria monocytogenes is a major concern in food industries. The aim of this work was to elucidate the effect of nutrient limitation on both biofilm architecture and on the viability of the bacteria in microfluidic growth conditions. Biofilm formation by two L. monocytogenes strains was performed in a rich medium (BHI) and in a 10-fold diluted BHI (BHI/10) at 30°C for 24 h by using both static conditions and the microfluidic system Bioflux. In dynamic conditions, biofilms grown in rich and poor medium showed significant differences as well in structure and in the resulting biovolume. In BHI/10, biofilm was organized in a knitted network where cells formed long chains, whereas in the rich medium, the observed structure was homogeneous cellular multilayers. Biofilm biovolume production in BHI/10 was significantly higher than in BHI in these dynamic conditions. Interestingly, biovolume of dead cells in biofilms formed under limited nutrient conditions (BHI/10) was significantly higher than in biofilms formed in the BHI medium. In the other hand, in static conditions, biofilm is organized in a multilayer cells and dispersed cells in a rich medium BHI and poor medium BHI/10 respectively. There was significantly more biomass in the rich medium compared to BHI/10 but no difference was noted in the dead/damaged subpopulation showing how L. monocytogenes biofilm could be affected by the growth conditions. This work demonstrated that nutrient concentration affects biofilm structure and the proportion of dead cells in biofilms under microfluidic condition. Our study also showed that limited nutrients play an important role in the structural stability of L. monocytogenes biofilm by enhancing cell death and liberating extracellular DNA.

  17. Portable laser speckle perfusion imaging system based on digital signal processor.

    PubMed

    Tang, Xuejun; Feng, Nengyun; Sun, Xiaoli; Li, Pengcheng; Luo, Qingming

    2010-12-01

    The ability to monitor blood flow in vivo is of major importance in clinical diagnosis and in basic researches of life science. As a noninvasive full-field technique without the need of scanning, laser speckle contrast imaging (LSCI) is widely used to study blood flow with high spatial and temporal resolution. Current LSCI systems are based on personal computers for image processing with large size, which potentially limit the widespread clinical utility. The need for portable laser speckle contrast imaging system that does not compromise processing efficiency is crucial in clinical diagnosis. However, the processing of laser speckle contrast images is time-consuming due to the heavy calculation for enormous high-resolution image data. To address this problem, a portable laser speckle perfusion imaging system based on digital signal processor (DSP) and the algorithm which is suitable for DSP is described. With highly integrated DSP and the algorithm, we have markedly reduced the size and weight of the system as well as its energy consumption while preserving the high processing speed. In vivo experiments demonstrate that our portable laser speckle perfusion imaging system can obtain blood flow images at 25 frames per second with the resolution of 640 × 480 pixels. The portable and lightweight features make it capable of being adapted to a wide variety of application areas such as research laboratory, operating room, ambulance, and even disaster site.

  18. Prediction of the micro-fluid dynamic environment imposed to three-dimensional engineered cell systems in bioreactors.

    PubMed

    Boschetti, Federica; Raimondi, Manuela Teresa; Migliavacca, Francesco; Dubini, Gabriele

    2006-01-01

    Bioreactors allowing culture medium perfusion overcome diffusion limitations associated with static culturing and provide flow-mediated mechanical stimuli. The hydrodynamic stress imposed to cells will depend not only on the culture medium flow rate, but also on the scaffold three-dimensional (3D) micro-architecture. We developed a CFD model of the flow of culture medium through a 3D scaffold of homogeneous geometry, with the aim of predicting the shear stress acting on cells as a function of parameters that can be controlled during the scaffold fabrication process, such as the scaffold porosity and the pore size, and during the cell culture, such as the medium flow rate and the diameter of the perfused scaffold section. We built three groups of models corresponding to three pore sizes: 50, 100 and 150 microm. Each group was made of four models corresponding to 59%, 65%, 77%, and 89% porosity. A commercial finite-element code was used to set up and solve the problem and to analyze the results. The mode value of shear stress varied between 2 and 5 mPa, and was obtained for a circular scaffold of 15.5 mm diameter, perfused by a flow rate of 0.5 ml/min. The simulations showed that the pore size is a variable strongly influencing the predicted shear stress level, whereas the porosity is a variable strongly affecting the statistical distribution of the shear stresses, but not their magnitude. Our results provide a basis for the completion of more exhaustive quantitative studies to further assess the relationship between perfusion, at known micro-fluid dynamic conditions, and tissue growth in vitro.

  19. Acoustic Filtration, Fractionation, and Mixing in Microfluidic Systems

    SciTech Connect

    Wang, A; Fisher, K

    2002-02-04

    This project is concerned with the research and development of a technique to manipulate small particles using acoustic energy coupled into a fluid filled plastic or glass sample chamber. These resulting miniaturized systems combine high functionality with an inexpensive, disposable sample chamber. Our approach to this problem is based on a combination of sophisticated modeling tools in conjunction with laboratory experiments. The design methodology is summarized in Figure 1. The process begins by investigating a wide range of device parameters using a one-dimensional analytical approximation. The results of these initial parameter studies are incorporated into a sophisticated three-dimensional multi-physics finite element code. From these simulations the optimized designs are prototyped and experimentally tested. The results of the experimental observations are then used to improve analytical approximations and the process is repeated as necessary.

  20. Pressure Stabilizer for Reproducible Picoinjection in Droplet Microfluidic Systems

    PubMed Central

    Rhee, Minsoung; Light, Yooli K.; Yilmaz, Suzan; Adams, Paul D.; Saxena, Deepak

    2014-01-01

    Picoinjection is a promising technique to add reagents into pre-formed emulsion droplets on chip; however, it is sensitive to pressure fluctuation, making stable operation of the picoinjector challenging. We present a chip architecture using a simple pressure stabilizer for consistent and highly reproducible picoinjection in multi-step biochemical assays with droplets. Incorporation of the stabilizer immediately upstream of a picoinjector or a combination of injectors greatly reduces pressure fluctuations enabling reproducible and effective picoinjection in systems where the pressure varies actively during operation. We demonstrate the effectiveness of the pressure stabilizer for an integrated platform for on-demand encapsulation of bacterial cells followed by picoinjection of reagents for lysing the encapsulated cells. The pressure stabilizer was also used for picoinjection of multiple displacement amplification (MDA) reagents to achieve genomic DNA amplification of lysed bacterial cells. PMID:25270338

  1. Pressure stabilizer for reproducible picoinjection in droplet microfluidic systems.

    PubMed

    Rhee, Minsoung; Light, Yooli K; Yilmaz, Suzan; Adams, Paul D; Saxena, Deepak; Meagher, Robert J; Singh, Anup K

    2014-12-07

    Picoinjection is a promising technique to add reagents into pre-formed emulsion droplets on chip however, it is sensitive to pressure fluctuation, making stable operation of the picoinjector challenging. We present a chip architecture using a simple pressure stabilizer for consistent and highly reproducible picoinjection in multi-step biochemical assays with droplets. Incorporation of the stabilizer immediately upstream of a picoinjector or a combination of injectors greatly reduces pressure fluctuations enabling reproducible and effective picoinjection in systems where the pressure varies actively during operation. We demonstrate the effectiveness of the pressure stabilizer for an integrated platform for on-demand encapsulation of bacterial cells followed by picoinjection of reagents for lysing the encapsulated cells. The pressure stabilizer was also used for picoinjection of multiple displacement amplification (MDA) reagents to achieve genomic DNA amplification of lysed bacterial cells.

  2. Low power integrated pumping and valving arrays for microfluidic systems

    DOEpatents

    Krulevitch, Peter A.; Benett, William J.; Rose, Klint A.; Hamilton, Julie; Maghribi, Mariam

    2006-04-11

    Low power integrated pumping and valving arrays which provide a revolutionary approach for performing pumping and valving approach for performing pumping and valving operations in microfabricated fluidic systems for applications such as medical diagnostic microchips. Traditional methods rely on external, large pressure sources that defeat the advantages of miniaturization. Previously demonstrated microfabrication devices are power and voltage intensive, only function at sufficient pressure to be broadly applicable. This approach integrates a lower power, high-pressure source with a polymer, ceramic, or metal plug enclosed within a microchannel, analogous to a microsyringe. When the pressure source is activated, the polymer plug slides within the microchannel, pumping the fluid on the opposite side of the plug without allowing fluid to leak around the plug. The plugs also can serve as microvalves.

  3. Biodegradability and platelets adhesion assessment of magnesium-based alloys using a microfluidic system

    PubMed Central

    Liu, Lumei; Koo, Youngmi; Collins, Boyce; Xu, Zhigang; Sankar, Jagannathan

    2017-01-01

    Magnesium (Mg)-based stents are extensively explored to alleviate atherosclerosis due to their biodegradability and relative hemocompatibility. To ensure the quality, safety and cost-efficacy of bioresorbable scaffolds and full utilization of the material tunability afforded by alloying, it is critical to access degradability and thrombosis potential of Mg-based alloys using improved in vitro models that mimic as closely as possible the in vivo microenvironment. In this study, we investigated biodegradation and initial thrombogenic behavior of Mg-based alloys at the interface between Mg alloys’ surface and simulated physiological environment using a microfluidic system. The degradation properties of Mg-based alloys WE43, AZ31, ZWEK-L, and ZWEK-C were evaluated in complete culture medium and their thrombosis potentials in platelet rich plasma, respectively. The results show that 1) physiological shear stress increased the corrosion rate and decreased platelets adhesion rate as compared to static immersion; 2) secondary phases and impurities in material composition induced galvanic corrosion, resulting in higher corrosion resistance and platelet adhesion rate; 3) Mg-based alloys with higher corrosion rate showed higher platelets adhesion rate. We conclude that a microfluidic-based in vitro system allows evaluation of biodegradation behaviors and platelets responses of Mg-based alloys under specific shear stress, and degradability is related to platelets adhesion. PMID:28797069

  4. Standard addition/absorption detection microfluidic system for salt error-free nitrite determination.

    PubMed

    Ahn, Jae-Hoon; Jo, Kyoung Ho; Hahn, Jong Hoon

    2015-07-30

    A continuous-flow microfluidic chip-based standard addition/absorption detection system has been developed for accurate determination of nitrite in water of varying salinity. The absorption detection of nitrite is made via color development using the Griess reaction. We have found the yield of the reaction is significantly affected by salinity (e.g., -12% error for 30‰ NaCl, 50.0 μg L(-1)N-NO2(-) solution). The microchip has been designed to perform standard addition, color development, and absorbance detection in sequence. To effectively block stray light, the microchip made from black poly(dimethylsiloxane) is placed on the top of a compact housing that accommodates a light-emitting diode, a photomultiplier tube, and an interference filter, where the light source and the detector are optically isolated. An 80-mm liquid-core waveguide mounted on the chip externally has been employed as the absorption detection flow cell. These designs for optics secure a wide linear response range (up to 500 μg L(-1)N-NO2(-)) and a low detection limit (0.12 μg L(-1)N-NO2(-) = 8.6 nM N-NO2(-), S/N = 3). From determination of nitrite in standard samples and real samples collected from an estuary, it has been demonstrated that our microfluidic system is highly accurate (<1% RSD, n = 3) and precise (<1% RSD, n = 3).

  5. 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

  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. Biodegradability and platelets adhesion assessment of magnesium-based alloys using a microfluidic system.

    PubMed

    Liu, Lumei; Koo, Youngmi; Collins, Boyce; Xu, Zhigang; Sankar, Jagannathan; Yun, Yeoheung

    2017-01-01

    Magnesium (Mg)-based stents are extensively explored to alleviate atherosclerosis due to their biodegradability and relative hemocompatibility. To ensure the quality, safety and cost-efficacy of bioresorbable scaffolds and full utilization of the material tunability afforded by alloying, it is critical to access degradability and thrombosis potential of Mg-based alloys using improved in vitro models that mimic as closely as possible the in vivo microenvironment. In this study, we investigated biodegradation and initial thrombogenic behavior of Mg-based alloys at the interface between Mg alloys' surface and simulated physiological environment using a microfluidic system. The degradation properties of Mg-based alloys WE43, AZ31, ZWEK-L, and ZWEK-C were evaluated in complete culture medium and their thrombosis potentials in platelet rich plasma, respectively. The results show that 1) physiological shear stress increased the corrosion rate and decreased platelets adhesion rate as compared to static immersion; 2) secondary phases and impurities in material composition induced galvanic corrosion, resulting in higher corrosion resistance and platelet adhesion rate; 3) Mg-based alloys with higher corrosion rate showed higher platelets adhesion rate. We conclude that a microfluidic-based in vitro system allows evaluation of biodegradation behaviors and platelets responses of Mg-based alloys under specific shear stress, and degradability is related to platelets adhesion.

  8. A microfluidic system to study cytoadhesion of Plasmodium falciparum infected erythrocytes to primary brain microvascularendothelial cells

    PubMed Central

    Herricks, Thurston; Seydel, Karl B.; Turner, George; Molyneux, Malcolm; Heyderman, Robert; Taylor, Terrie; Rathod, Pradipsinh K.

    2013-01-01

    The cellular events leading to severe and complicated malaria in some Plasmodium falciparum infections are poorly understood. Additional tools are required to better understand the pathogenesis of this disease. In this technical report, we describe a microfluidic culture system and image processing algorithms that were developed to observe cytoadhesion interactions of P. falciparum parasitized erythrocytes rolling on primary brain microvascularendothelial cells. We isolated and cultured human primary vascular endothelial cells in a closed loop microfluidic culture system where a peristaltic pump and media reservoirs were integrated onto a microscope stage insert. We developed image processing methods to enhance contrast of rolling parasitized erythrocytes on endothelial cells and to estimate the local wall shear stress. The velocity of parasitized erythrocytes rolling on primary brain microvascularendothelial cells was then measured under physiologically relevant wall shear stresses. Finally, we deployed this method successfully at a field site in Blantyre, Malawi. The method is a promising new tool for the investigation of the pathogenesis of severe malaria. PMID:21743938

  9. A Bacterial Continuous Culture System Based on a Microfluidic Droplet Open Reactor.

    PubMed

    Ito, Manami; Sugiura, Haruka; Ayukawa, Shotaro; Kiga, Daisuke; Takinoue, Masahiro

    2016-01-01

    Recently, micrometer-sized bacterial culture systems have attracted attention as useful tools for synthetic biology studies. Here, we present the development of a bacterial continuous culture system based on a microdroplet open reactor consisting of two types of water-in-oil microdroplets with diameters of several hundred micrometers. A continuous culture was realized the through supply of nutrient substrates and the removal of waste and excess bacterial cells based on repeated fusion and fission of droplets. The growth dynamics was controlled by the interval of fusion. We constructed a microfluidic system and quantitatively assessed the dynamics of the bacterial growth using a mathematical model. This system will facilitate the study of synthetic biology and metabolic engineering in the future.

  10. Sensitive Optical and Microfluidic Systems for Cellular Analyses

    NASA Astrophysics Data System (ADS)

    Schiro, Perry G.

    Investigating rare cells and heterogeneous subpopulations is challenging for a myriad reasons. This dissertation describes novel techniques to analyze single molecules, synaptic vesicles, and rare circulating tumor cells. The eDAR platform for isolating rare cells in fluids provides a new method to monitor breast cancer status in patients as well as to guide research for personalized treatment and efficacy. In a side-by-side comparison with CellSearch, eDAR detected CTCs in all 20 Stage IV metastatic breast cancer patients while the CellSearch system found CTCs in just 8 patients. The single-molecule capillary electrophoresis technology is a method to characterize an entire sample one molecule at a time, providing detailed information about the absolute number and nature of molecules present in a sample. The nFASS platform has the potential to apply the advantages that currently exist in flow cytometry to the study of items on a much smaller scale such as subcellular organelles and nanometer-sized objects. For example, the isolation of subpopulations of synaptic vesicles will allow for detailed protein quantification and identification in the study of neurological diseases. These tools facilitate fundamental investigation of objects ranging from single molecules to single cells.

  11. In systemic sclerosis skin perfusion of hands is reduced and may predict the occurrence of new digital ulcers.

    PubMed

    Barbano, Biagio; Marra, Alessandro Maria; Quarta, Silvia; Gigante, Antonietta; Barilaro, Giuseppe; Gasperini, Maria Ludovica; Rosato, Edoardo

    2017-03-01

    Systemic sclerosis (SSc) patients are at high risk for the development of ischemic digital ulcers (DUs). The aim of this study was to assess in SSc patients a correlation between skin perfusion evaluated by LDPI and DUs and to evaluate the prognostic value of skin perfusion to predict the new DUs occurrence. Fifty eight (47 female, 11 male) SSc patients were enrolled. Skin perfusion of hands and region of interest (ROIs) was measured by Laser Doppler perfusion Imager (LDPI). The proximal-distal gradient (PDG) was present when the perfusion mean difference between ROI1 and ROI2 was >30 pU. The skin perfusion of hands is lower in SSc patients than in healthy controls. The skin perfusion decreased with severity of capillaroscopic damage. Both mean perfusion of hand and PDG are significantly (p<0.01 and p<0.0001, respectively) lower in SSc patients with new DUs than in SSc patients without DUs. Only 2 of 11 SSc patients (18.2%) with PDG developed new digital ulcers, conversely 36 of 47 (76.6%) SSc patients without PDG developed new digital ulcers (p<0.001). The ROC curves demonstrated a good accuracy of new DUs prediction for PDG (0.78, p<0.0001). Using this cut-off value of 30 pU, RR for new DUs development in SSc patients without PDG is 4,2 (p<0.001). LDPI indices could be used in association to the capillaroscopic and clinical findings or serological tests in the identification of patients at high risk of developing DUs.

  12. Quantitative myocardial perfusion imaging in a porcine ischemia model using a prototype spectral detector CT system.

    PubMed

    Fahmi, Rachid; Eck, Brendan L; Levi, Jacob; Fares, Anas; Dhanantwari, Amar; Vembar, Mani; Bezerra, Hiram G; Wilson, David L

    2016-03-21

    We optimized and evaluated dynamic myocardial CT perfusion (CTP) imaging on a prototype spectral detector CT (SDCT) scanner. Simultaneous acquisition of energy sensitive projections on the SDCT system enabled projection-based material decomposition, which typically performs better than image-based decomposition required by some other system designs. In addition to virtual monoenergetic, or keV images, the SDCT provided conventional (kVp) images, allowing us to compare and contrast results. Physical phantom measurements demonstrated linearity of keV images, a requirement for quantitative perfusion. Comparisons of kVp to keV images demonstrated very significant reductions in tell-tale beam hardening (BH) artifacts in both phantom and pig images. In phantom images, consideration of iodine contrast to noise ratio and small residual BH artifacts suggested optimum processing at 70 keV. The processing pipeline for dynamic CTP measurements included 4D image registration, spatio-temporal noise filtering, and model-independent singular value decomposition deconvolution, automatically regularized using the L-curve criterion. In normal pig CTP, 70 keV perfusion estimates were homogeneous throughout the myocardium. At 120 kVp, flow was reduced by more than 20% on the BH-hypo-enhanced myocardium, a range that might falsely indicate actionable ischemia, considering the 0.8 threshold for actionable FFR. With partial occlusion of the left anterior descending (LAD) artery (FFR < 0.8), perfusion defects at 70 keV were correctly identified in the LAD territory. At 120 kVp, BH affected the size and flow in the ischemic area; e.g. with FFR ≈ 0.65, the anterior-to-lateral flow ratio was 0.29 ± 0.01, over-estimating stenosis severity as compared to 0.42 ± 0.01 (p < 0.05) at 70 keV. On the non-ischemic inferior wall (not a LAD territory), the flow ratio was 0.50 ± 0.04 falsely indicating an actionable ischemic condition in a healthy territory. This ratio was 1.00 ± 0.08 at 70 ke

  13. Quantitative myocardial perfusion imaging in a porcine ischemia model using a prototype spectral detector CT system

    NASA Astrophysics Data System (ADS)

    Fahmi, Rachid; Eck, Brendan L.; Levi, Jacob; Fares, Anas; Dhanantwari, Amar; Vembar, Mani; Bezerra, Hiram G.; Wilson, David L.

    2016-03-01

    We optimized and evaluated dynamic myocardial CT perfusion (CTP) imaging on a prototype spectral detector CT (SDCT) scanner. Simultaneous acquisition of energy sensitive projections on the SDCT system enabled projection-based material decomposition, which typically performs better than image-based decomposition required by some other system designs. In addition to virtual monoenergetic, or keV images, the SDCT provided conventional (kVp) images, allowing us to compare and contrast results. Physical phantom measurements demonstrated linearity of keV images, a requirement for quantitative perfusion. Comparisons of kVp to keV images demonstrated very significant reductions in tell-tale beam hardening (BH) artifacts in both phantom and pig images. In phantom images, consideration of iodine contrast to noise ratio and small residual BH artifacts suggested optimum processing at 70 keV. The processing pipeline for dynamic CTP measurements included 4D image registration, spatio-temporal noise filtering, and model-independent singular value decomposition deconvolution, automatically regularized using the L-curve criterion. In normal pig CTP, 70 keV perfusion estimates were homogeneous throughout the myocardium. At 120 kVp, flow was reduced by more than 20% on the BH-hypo-enhanced myocardium, a range that might falsely indicate actionable ischemia, considering the 0.8 threshold for actionable FFR. With partial occlusion of the left anterior descending (LAD) artery (FFR  <  0.8), perfusion defects at 70 keV were correctly identified in the LAD territory. At 120 kVp, BH affected the size and flow in the ischemic area; e.g. with FFR ≈ 0.65, the anterior-to-lateral flow ratio was 0.29  ±  0.01, over-estimating stenosis severity as compared to 0.42  ±  0.01 (p  <  0.05) at 70 keV. On the non-ischemic inferior wall (not a LAD territory), the flow ratio was 0.50  ±  0.04 falsely indicating an actionable ischemic condition in a healthy

  14. A Scalable Perfusion Culture System with Miniature Peristaltic Pumps for Live-Cell Imaging Assays with Provision for Microfabricated Scaffolds

    PubMed Central

    Balakrishnan, Sreenath; Suma, M.S.; Raju, Shilpa R.; Bhargav, Santosh D.B.; Arunima, S.; Das, Saumitra

    2015-01-01

    Abstract We present a perfusion culture system with miniature bioreactors and peristaltic pumps. The bioreactors are designed for perfusion, live-cell imaging studies, easy incorporation of microfabricated scaffolds, and convenience of operation in standard cell culture techniques. By combining with miniature peristaltic pumps—one for each bioreactor to avoid cross-contamination and to maintain desired flow rate in each—we have made a culture system that facilitates perfusion culture inside standard incubators. This scalable system can support multiple parallel perfusion experiments. The major components are fabricated by three-dimensional printing using VeroWhite, which we show to be amenable to ex vivo cell culture. Furthermore, the components of the system can be reused, thus making it economical. We validate the system and illustrate its versatility by culturing primary rat hepatocytes, live imaging the growth of mouse fibroblasts (NIH 3T3) on microfabricated ring-scaffolds inserted into the bioreactor, performing perfusion culture of breast cancer cells (MCF7), and high-magnification imaging of hepatocarcinoma cells (HuH7). PMID:26309810

  15. Developing optimal input design strategies in cancer systems biology with applications to microfluidic device engineering

    PubMed Central

    Menolascina, Filippo; Bellomo, Domenico; Maiwald, Thomas; Bevilacqua, Vitoantonio; Ciminelli, Caterina; Paradiso, Angelo; Tommasi, Stefania

    2009-01-01

    Background Mechanistic models are becoming more and more popular in Systems Biology; identification and control of models underlying biochemical pathways of interest in oncology is a primary goal in this field. Unfortunately the scarce availability of data still limits our understanding of the intrinsic characteristics of complex pathologies like cancer: acquiring information for a system understanding of complex reaction networks is time consuming and expensive. Stimulus response experiments (SRE) have been used to gain a deeper insight into the details of biochemical mechanisms underlying cell life and functioning. Optimisation of the input time-profile, however, still remains a major area of research due to the complexity of the problem and its relevance for the task of information retrieval in systems biology-related experiments. Results We have addressed the problem of quantifying the information associated to an experiment using the Fisher Information Matrix and we have proposed an optimal experimental design strategy based on evolutionary algorithm to cope with the problem of information gathering in Systems Biology. On the basis of the theoretical results obtained in the field of control systems theory, we have studied the dynamical properties of the signals to be used in cell stimulation. The results of this study have been used to develop a microfluidic device for the automation of the process of cell stimulation for system identification. Conclusion We have applied the proposed approach to the Epidermal Growth Factor Receptor pathway and we observed that it minimises the amount of parametric uncertainty associated to the identified model. A statistical framework based on Monte-Carlo estimations of the uncertainty ellipsoid confirmed the superiority of optimally designed experiments over canonical inputs. The proposed approach can be easily extended to multiobjective formulations that can also take advantage of identifiability analysis. Moreover, the

  16. Fabrication of microfluidic system for the assessment of cell migration on 3D micropatterned substrates.

    PubMed

    Lee, Eun-Joong; Hwang, Chang-Mo; Baek, Dong-Hyun; Lee, Sang-Hoon

    2009-01-01

    Cell migration and proliferation are major process in wound healing, cancer metastasis and organogenesis during development. Many cells are related to recovery process of wound. Especially, fibroblasts act an important role in wound healing. Various cytokines such as platelet derived growth factor (PDGF) can induce fibroblast migration and widely studied to investigate the cell response under controlled cytokine microenvironments during wound healing. In real tissue healing process, cell microenvironments change with tissue types and anatomical characteristics of organs. With microfluidic system, we tried to mimic the natural microenvironment of wound healing, with gradient of PDGF, a fibroblast migration inducing cytokine, and patterned substrate with different orientation to PDGF gradient. Fibroblasts cultured in PDGF gradient micro fluidic chip showed cell migration under various micro environmental gradient conditions. Cells were cultured under PDGF gradient condition and different substrate pattern. Mouse fibroblast L929 cells were cultured in the microfluidic gradient. The results showed that most cells migrated along the substrate topological patterns under high concentration of PDGF. We developed long range sustaining micro fluidic channel and could analyze cell migration along the gradient of PDGF. Also, the cell migration on patterned extracellular environment shows that cells migrate along the extracellular 3D pattern rather than directly along the cytokine gradient when the pattern height is less than 1 microm. In this study, we could demonstrate that the extracellular pattern is more dominant to cell migration in combination with cytokine gradient in the wounded tissue when the environmental cues are 20 microm.

  17. A Review of Heating and Temperature Control in Microfluidic Systems: Techniques and Applications

    PubMed Central

    Miralles, Vincent; Huerre, Axel; Malloggi, Florent; Jullien, Marie-Caroline

    2013-01-01

    This review presents an overview of the different techniques developed over the last decade to regulate the temperature within microfluidic systems. A variety of different approaches has been adopted, from external heating sources to Joule heating, microwaves or the use of lasers to cite just a few examples. The scope of the technical solutions developed to date is impressive and encompasses for instance temperature ramp rates ranging from 0.1 to 2,000 °C/s leading to homogeneous temperatures from −3 °C to 120 °C, and constant gradients from 6 to 40 °C/mm with a fair degree of accuracy. We also examine some recent strategies developed for applications such as digital microfluidics, where integration of a heating source to generate a temperature gradient offers control of a key parameter, without necessarily requiring great accuracy. Conversely, Temperature Gradient Focusing requires high accuracy in order to control both the concentration and separation of charged species. In addition, the Polymerase Chain Reaction requires both accuracy (homogeneous temperature) and integration to carry out demanding heating cycles. The spectrum of applications requiring temperature regulation is growing rapidly with increasingly important implications for the physical, chemical and biotechnological sectors, depending on the relevant heating technique. PMID:26835667

  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. Microfluidic co-culture system for cancer migratory analysis and anti-metastatic drugs screening

    PubMed Central

    Mi, Shengli; Du, Zhichang; Xu, Yuanyuan; Wu, Zhengjie; Qian, Xiang; Zhang, Min; Sun, Wei

    2016-01-01

    Tumour metastasis is an important reason for cancer death, and cancer cell migration is an important step in the process of tumour metastasis. Studying cancer cell migration is of great significance. Here, we present a novel microfluidic co-culture system and establish mild, moderate and severe cancer models by using HMEpiC and MDA-MB–231 cells to study cancer cell migration and anti-cancer drug screening. Using this device, we achieved high cell viability (over 90%) and a stable analysis of the migration ability of cancer cells. We observed that the density of the cancer cells determined the probability of the occurrence of metastatic cells and that the induction of normal cells affected the metastatic velocity of each cancer cell. We verified that the increase in the migration ability of MDA-MB-231 cells co-cultured with HMEpiC cells was relative to the increased secretion of IL-6 and that this was verified by an IL-6 inhibitor assay. This co-culture also led to decreased CK-14 secretion and morphological changes in HMEpiC cells. Finally, significant inhibition of paclitaxel and tamoxifen on cancer migration was observed. Taken together, our microfluidic device could be a useful tool for the quantitation of the migratory capability and anti-metastatic drug screening. PMID:27762336

  20. Rapid microfluidic solid-phase extraction system for hyper-methylated DNA enrichment and epigenetic analysis

    PubMed Central

    De, Arpita; Sparreboom, Wouter; van den Berg, Albert; Carlen, Edwin T.

    2014-01-01

    Genetic sequence and hyper-methylation profile information from the promoter regions of tumor suppressor genes are important for cancer disease investigation. Since hyper-methylated DNA (hm-DNA) is typically present in ultra-low concentrations in biological samples, such as stool, urine, and saliva, sample enrichment and amplification is typically required before detection. We present a rapid microfluidic solid phase extraction (μSPE) system for the capture and elution of low concentrations of hm-DNA (≤1 ng ml−1), based on a protein-DNA capture surface, into small volumes using a passive microfluidic lab-on-a-chip platform. All assay steps have been qualitatively characterized using a real-time surface plasmon resonance (SPR) biosensor, and quantitatively characterized using fluorescence spectroscopy. The hm-DNA capture/elution process requires less than 5 min with an efficiency of 71% using a 25 μl elution volume and 92% efficiency using a 100 μl elution volume. PMID:25538809

  1. Single Cell Mass Measurement Using Drag Force Inside Lab-on-Chip Microfluidics System.

    PubMed

    Rahman, Md Habibur; Ahmad, Mohd Ridzuan; Takeuchi, Masaru; Nakajima, Masahiro; Hasegawa, Yasuhisa; Fukuda, Toshio

    2015-12-01

    Single cell mass (SCM) is an intrinsic property of single cell, it arouses a great interest among scientists as cell mass depends on the synthesis of proteins, DNA replication, cell wall stiffness, cell cytoplasm density, cell growth, ribosome, and other analogous of organisms. To date, several great strides have been taken to the advancements of SCM measurement techniques. Nevertheless, more works are required to enable the technology to push frontier in deep analysis of SCM measurement, hence to elucidate intracellular properties. In this paper, we present a lab-on-chip microfluidics system for SCM measurement, related with the force required to drag a single cell and Newton's law of motion inside microfluidics channel. Drag force on the cell was generated by a pressure driven syringe micropump and the motion of the cell was measured using optical observation under an inverted microscope. This approach of measuring SCM was calibrated using known mass (77.3 pg) of a polystyrene particle of 5.2 μm diameter. Furthermore, we used Saccharomyces cerevisiae baker's yeast cells of different sizes ([Formula: see text] diameter) for SCM measurement. Mass of 4.4 μm diameter of single yeast cell was measured as 2.12 pg which is in the range of previously reported single yeast cell mass (2-3 pg). In addition, we also studied the relation between SCM and single cell size. Results showed that single yeast cell mass increases exponentially with the increasing of single cell size.

  2. Single Cell Mass Measurement Using Drag ForceInside Lab-on-Chip Microfluidics System.

    PubMed

    Rahman, Md; Ahmad, Mohd; Takeuchi, Masaru; Nakajima, Masahiro; Hasegawa, Yasuhisa; Fukuda, Toshio

    2015-12-22

    Single Cell Mass (SCM) is an intrinsic property of single cell, it arouses a great interest among scientists as cell mass depends on the synthesis of proteins, DNA replication, cell wall stiffness, cell cytoplasm density, cell growth, ribosome and other analogous of organisms. To date, several great strides have been taken to the advancements of SCM measurement techniques. Nevertheless, more works are required to enable the technology to push frontier in deep analysis of SCM measurement, hence to elucidate intracellular properties. In this paper, we present a Lab-on-Chip microfluidics system for SCM measurement, related with the force required to drag a single cell and Newton's law of motion inside microfluidics channel. Drag force on the cell was generated by a pressure driven syringe micropump and the motion of the cell was measured using optical observation under an inverted microscope. This approach of measuring SCM was calibrated using known mass (77.3 pg) of a polystyrene particle of 5.2 μm diameter. Furthermore, we used Saccharomyces cerevisiae baker's yeast cells of different sizes (2-7 μm diameter) for SCM measurement. Mass of 4.4 μm diameter of single yeast cell was measured as 2.12 pg which is in the range of previously reported single yeast cell mass (2-3 pg). In addition, we also studied the relation between SCM and single cell size. Results showed that single yeast cell mass increases exponentially with the increasing of single cell size.

  3. 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.

  4. Microfluidic tectonics platform: A colorimetric, disposable botulinum toxin enzyme-linked immunosorbent assay system.

    PubMed

    Moorthy, Jaisree; Mensing, Glennys A; Kim, Dongshin; Mohanty, Swomitra; Eddington, David T; Tepp, William H; Johnson, Eric A; Beebe, David J

    2004-06-01

    A fabrication platform for realizing integrated microfluidic devices is discussed. The platform allows for creating specific microsystems for multistep assays in an ad hoc manner as the components that perform the assay steps can be created at any location inside the device via in situ fabrication. The platform was utilized to create a prototype microsystem for detecting botulinum neurotoxin directly from whole blood. Process steps such as sample preparation by filtration, mixing and incubation with reagents was carried out on the device. Various microfluidic components such as channel network, valves and porous filter were fabricated from prepolymer mixture consisting of monomer, cross-linker and a photoinitiator. For detection of the toxoid, biotinylated antibodies were immobilized on streptavidin-functionalized agarose gel beads. The gel beads were introduced into the device and were used as readouts. Enzymatic reaction between alkaline phosphatase (on secondary antibody) and substrate produced an insoluble, colored precipitate that coated the beads thus making the readout visible to the naked eye. Clinically relevant amounts of the toxin can be detected from whole blood using the portable enzyme-linked immunosorbent assay (ELISA) system. Multiple layers can be realized for effective space utilization and creating a three-dimensional (3-D) chaotic mixer. In addition, external materials such as membranes can be incorporated into the device as components. Individual components that were necessary to perform these steps were characterized, and their mutual compatibility is also discussed.

  5. Rapid microfluidic solid-phase extraction system for hyper-methylated DNA enrichment and epigenetic analysis.

    PubMed

    De, Arpita; Sparreboom, Wouter; van den Berg, Albert; Carlen, Edwin T

    2014-09-01

    Genetic sequence and hyper-methylation profile information from the promoter regions of tumor suppressor genes are important for cancer disease investigation. Since hyper-methylated DNA (hm-DNA) is typically present in ultra-low concentrations in biological samples, such as stool, urine, and saliva, sample enrichment and amplification is typically required before detection. We present a rapid microfluidic solid phase extraction (μSPE) system for the capture and elution of low concentrations of hm-DNA (≤1 ng ml(-1)), based on a protein-DNA capture surface, into small volumes using a passive microfluidic lab-on-a-chip platform. All assay steps have been qualitatively characterized using a real-time surface plasmon resonance (SPR) biosensor, and quantitatively characterized using fluorescence spectroscopy. The hm-DNA capture/elution process requires less than 5 min with an efficiency of 71% using a 25 μl elution volume and 92% efficiency using a 100 μl elution volume.

  6. Rapid Prototyping of Poly(methyl methacrylate) Microfluidic Systems Using Solvent Imprinting and Bonding

    PubMed Central

    Sun, Xiuhua; Peeni, Bridget A.; Yang, Weichun; Becerril, Hector A.

    2011-01-01

    We have developed a method for rapid prototyping of hard polymer microfluidic systems using solvent imprinting and bonding. We investigated the applicability of patterned SU-8 photoresist on glass as an easily fabricated template for solvent imprinting. Poly(methyl methacrylate) (PMMA) exposed to acetonitrile for 2 min then had an SU-8 template pressed into the surface for 10 min, which provided appropriately imprinted channels and a suitable surface for bonding. After a PMMA cover plate had also been exposed to acetonitrile for 2 min, the imprinted and top PMMA pieces could be bonded together at room temperature with appropriate pressure. The total fabrication time was less than 15 min. Under the optimized fabrication conditions, nearly 30 PMMA chips could be replicated using a single patterned SU-8 master with high chip-to-chip reproducibility. Relative standard deviations were 2.3% and 5.4% for the widths and depths of the replicated channels, respectively. Fluorescently labeled amino acid and peptide mixtures were baseline separated using these PMMA microchips in <15 s. Theoretical plate numbers in excess of 5000 were obtained for a ~3 cm separation distance, and the migration time relative standard deviation for an amino acid peak was 1.5% for intra-day and 2.2% for inter-day analysis. This new solvent imprinting and bonding approach significantly simplifies the process for fabricating microfluidic structures in hard polymers such as PMMA. PMID:17466320

  7. Thermoplastic elastomer gels: an advanced substrate for microfluidic chemical analysis systems.

    PubMed

    Sudarsan, Arjun P; Wang, Jian; Ugaz, Victor M

    2005-08-15

    We demonstrate the use of thermoplastic elastomer gels as advanced substrates for construction of complex microfluidic networks suitable for use in miniaturized chemical analysis systems. These gels are synthesized by combining inexpensive polystyrene-(polyethylene/polybutylene)-polystyrene triblock copolymers with a hydrocarbon extender oil for which the ethylene/butylene midblocks are selectively miscible. The insoluble styrene end blocks phase separate into localized nanodomains, resulting in the formation of an optically transparent, viscoelastic, and biocompatible gel network that is melt-processable at temperatures in the vicinity of 100 degrees C. This unique combination of properties allows microfluidic channels to be fabricated in a matter of minutes by simply making impressions of the negative relief structures on heated master molds. Melt processability allows multiple impressions to be made against different masters to construct complex geometries incorporating multi-height features within the same microchannel. Intricate interconnected multilayered structures are also easily fabricated owing to the ability to bond and seal multiple layers by briefly heating the material at the bond interface. Thermal and mechanical properties are tunable over a wide range through proper selection of gel composition.

  8. An Automated Microfluidic Chemostat for a Self-Replicating System of DNA Constructs

    NASA Astrophysics Data System (ADS)

    Bergman, Andrew; He, Xiaojin; Maass, Corinna; Sha, Ruojie; Mi, Yongli; Seeman, Nadrian; Chaikin, Paul

    2014-03-01

    We have modified a bacterial microchemostat1 for use in studying and optimizing a self-replicating system based on DNA constructs. The self-replication process we employ requires cycling temperature and UV light exposure. The base units of our system are DNA constructs that can recognize their complements using DNA ``sticky ends'' and can be covalently linked to one another through the use of a UV-crosslinkable nucleobase substitute. ``Seed particles'' of varying length are made by attaching two or more of these constructs and are added to and processed in this microfluidic system, which allows for temperature control, UV illumination and microscopic observation of fluorescence and FRET. Automation provides for a well-regulated and high-throughput testing and optimization of conditions.

  9. Oxygenation and perfusion monitoring with a hyperspectral camera system for chemical based tissue analysis of skin and organs.

    PubMed

    Holmer, Amadeus; Tetschke, Florian; Marotz, Jörg; Malberg, Hagen; Markgraf, Wenke; Thiele, Christine; Kulcke, Axel

    2016-11-01

    The monitoring of free flaps, free transplants or organs for transplantation still poses a problem in medicine. Available systems for the measurement of perfusion and oxygenation can only perform localized measurements and usually need contact with the tissue. Contact free hyperspectral imaging and near-infrared spectroscopy (NIRS) for the analysis of tissue oxygenation and perfusion have been used in many scientific studies with good results. But up to now the clinical and scientific application of this technology has been hindered by the lack of hyperspectral measurement systems usable in clinical practice. We will introduce the application of a new hyperspectral camera system for the quick and robust recording of remission spectra in the combined VIS and NIR spectral range with high spectral and spatial resolution. This new system can be applied for the clinical monitoring of free flaps and organs providing high quality oxygenation and perfusion images.

  10. Changes in mixed-function oxidase system in the perfused liver of the cold-acclimated rat

    NASA Astrophysics Data System (ADS)

    Takano, T.; Miyazaki, Y.; Motohashi, Y.; Yamada, K.

    1986-09-01

    Changes in the hepatic cytochrome P-450-dependent drug-metabolizing system were studied in perfused livers obtained from cold-acclimated male Wistar rats after 30 days of cold exposure (4‡C) when using hexobarbital as a substrate. In fasted animals the cold-acclimated rats showed higher levels of hexobarbital metabolic rates compared to control rats, but there was no significant difference in fed animals. The maximum rates of hexobarbital metabolism produced by xylitol perfusion were also significantly higher in the perfused liver of cold-acclimated rats. It was concluded that the function of the cytochrome P-450 system for hexobarbital in cold-acclimated rats changed due to both an increase in the activity of the cytochrome P-450 system and to changes in regulation of the cytochrome P-450 system by the supply of reducing equivalents.

  11. SU-E-QI-06: Design and Initial Validation of a Precise Capillary Phantom to Test Perfusion Systems

    SciTech Connect

    Wood, R; Iacobucci, G; Khobragade, P; Ying, L; Snyder, K; Wack, D; Rudin, S; Ionita, C

    2014-06-15

    Purpose: To design a precise perfusion phantom mimicking capillaries of the brain vasculature which could be used to test various perfusion protocols and algorithms which generate perfusion maps. Methods: A perfusion phantom was designed in Solidworks and built using additive manufacturing. The phantom was an overall cylindrical shape of diameter and height 20mm and containing capillaries of 200μm or 300μm which were parallel and in contact making up the inside volume where flow was allowed. We created a flow loop using a peristaltic pump and contrast agent was injected manually. Digital Subtraction Angiographic images and low contrast images with cone beam CT were acquired after the contrast was injected. These images were analyzed by our own code in LabVIEW software and Time-Density Curve, MTT and TTP was calculated. Results: Perfused area was visible in the cone beam CT images; however, individual capillaries were not distinguishable. The Time-Density Curve acquired was accurate, sensitive and repeatable. The parameters MTT, and TTP offered by the phantom were very sensitive to slight changes in the TDC shape. Conclusion: We have created a robust calibrating model for evaluation of existing perfusion data analysis systems. This approach is extremely sensitive to changes in the flow due to the high temporal resolution and could be used as a golden standard to assist developers in calibrating and testing of imaging perfusion systems and software algorithms. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.

  12. Perfusion Assessment with the SPY System after Arterial Venous Reversal for Upper Extremity Ischemia.

    PubMed

    Brooks, Darrell

    2014-07-01

    The timing and pattern of reperfusion following arterial- venous reversal (AVR) in patients with terminal ischemia of an upper extremity is not well understood. The current case series describes the timing and pattern of reperfusion observed in patients with terminal upper extremity ischemia who underwent AVR and repeated postoperative indocyanine green (ICG) angiography between 2004 and 2009. For all included patients, the SPY Near-Infrared Perfusion Assessment System permitted visualization of ICG-labeled blood flow for 60-second sampling periods at scheduled postoperative time points; outflow and rate and amplitude of inflow were objectively quantified with SPY-Q Analysis Toolkit image analysis software. The series comprised 6 male patients (mean age, 46 years) who presented with upper extremity ischemia related to hypothenar hammer syndrome (n = 2), embolism with patent foramen ovale (n = 2), atherosclerosis (n = 1), and avulsion amputation of the thumb (n = 1); the patient with the avulsion amputation was diagnosed with thromboangiitis obliterans at the time of replantation. AVR was successful in all 6 patients. In 5 of 6 patients, ICG angiography and SPY-based visualization/quantification showed that venous outflow and arterial inflow gradually normalized (versus unaffected digits) between postoperative days (PODs) 0 and 3 and was maintained at long-term follow-up (≥3 months); for the patient who underwent thumb replantation, perfusion normalized between POD 3 and month 5 follow-up. AVR effectively reestablished blood flow in patients with terminal upper extremity ischemia. ICG angiography with SPY technology revealed that, in most cases, kinetic curves, timing, and patterns of perfusion gradually normalized over several PODs.

  13. Perfusion Assessment with the SPY System after Arterial Venous Reversal for Upper Extremity Ischemia

    PubMed Central

    2014-01-01

    Background: The timing and pattern of reperfusion following arterial- venous reversal (AVR) in patients with terminal ischemia of an upper extremity is not well understood. Methods: The current case series describes the timing and pattern of reperfusion observed in patients with terminal upper extremity ischemia who underwent AVR and repeated postoperative indocyanine green (ICG) angiography between 2004 and 2009. For all included patients, the SPY Near-Infrared Perfusion Assessment System permitted visualization of ICG-labeled blood flow for 60-second sampling periods at scheduled postoperative time points; outflow and rate and amplitude of inflow were objectively quantified with SPY-Q Analysis Toolkit image analysis software. Results: The series comprised 6 male patients (mean age, 46 years) who presented with upper extremity ischemia related to hypothenar hammer syndrome (n = 2), embolism with patent foramen ovale (n = 2), atherosclerosis (n = 1), and avulsion amputation of the thumb (n = 1); the patient with the avulsion amputation was diagnosed with thromboangiitis obliterans at the time of replantation. AVR was successful in all 6 patients. In 5 of 6 patients, ICG angiography and SPY-based visualization/quantification showed that venous outflow and arterial inflow gradually normalized (versus unaffected digits) between postoperative days (PODs) 0 and 3 and was maintained at long-term follow-up (≥3 months); for the patient who underwent thumb replantation, perfusion normalized between POD 3 and month 5 follow-up. Conclusions: AVR effectively reestablished blood flow in patients with terminal upper extremity ischemia. ICG angiography with SPY technology revealed that, in most cases, kinetic curves, timing, and patterns of perfusion gradually normalized over several PODs. PMID:25426368

  14. Perfusion enhanced polydimethylsiloxane based scaffold cell culturing system for multi-well drug screening platform.

    PubMed

    Tania, Marshella; Hsu, Myat Noe; Png, Si Ning; Leo, Hwa Liang; Toh, Guoyang William; Birgersson, Erik

    2014-01-01

    Conventional two-dimensional cultures in monolayer and sandwich configuration have been used as a model for in vitro drug testing. However, these culture configurations do not present the actual in vivo liver cytoarchitecture for the hepatocytes cultures and thus they may compromise the cells liver-specific functions and their cuboidal morphology over longer term culture. In this study, we present a three-dimensional polydimethylsiloxane (PDMS) scaffold with interconnected spherical macropores for the culturing of rat liver cells (hepatocytes). The scaffolds were integrated into our perfusion enhanced bioreactor to improve the nutrients and gas supply for cell cultures. The liver-specific functions of the cell culture were assessed by their albumin and urea production, and the changes in the cell morphology were tracked by immunofluorescence staining over 9 days of culture period. N-Acetyl-Para-Amino-Phenol (acetaminophen) was used as drug model to investigate the response of cells to drug in our scaffold-bioreactor system. Our experimental results revealed that the perfusion enhanced PDMS-based scaffold system provides a more conducive microenvironment with better cell-to-cell contacts among the hepatocytes that maintains the culture specific enzymatic functions and their cuboidal morphology during the culturing period. The numerical simulation results further showed improved oxygen distribution within the culturing chamber with the scaffold providing an additional function of shielding the cell cultures from the potentially detrimental fluid induced shear stresses. In conclusion, this study could serve a crucial role as a platform for future preclinical hepatotoxicity testing.

  15. Hepatic perfusion abnormalities during treatment with hepatic arterial infusion chemotherapy: Value of CT arteriography using an implantable port system

    SciTech Connect

    Seki, Hiroshi; Kimura, Motomasa; Kamura, Takeshi; Miura, Tsutomu

    1996-05-01

    The purpose of this study was to evaluate CT arteriography (CTA) using an implantable port system in the detection of perfusion abnormalities occurring during hepatic arterial infusion chemotherapy (HAIC). In 51 patients with unresectable primary and metastatic liver tumors, who had implanted port systems for HAIC, CTA examinations through the infusion pump were performed. When perfusion abnormalities were found, selective angiography and/or digital subtraction angiography using the implantable port system were performed to determine the etiology. Forty-nine perfusion abnormalities were detected in 32 patients. Intrahepatic hypoperfusion was found in 24 cases. Of 11 patients in whom correction of the hypoperfusion was attempted, it was successful in 10. Of 13 patients in whom correction was not attempted, 6 patients showed progressive disease in nonperfused areas. Intrahepatic hyperperfusion was found in 14 cases, which showed no subsequent complication. Extrahepatic perfusion was found in 11 cases. We consider CTA to be useful in detecting perfusion abnormalities that may compromise HAIC. 22 refs., 3 figs., 3 tabs.

  16. Measurement of the microscopic viscosities of microfluids with a dynamic optical tweezers system

    PubMed Central

    Zhang, Yuquan; Wu, Xiaojing; Wang, Yijia; Zhu, Siwei; Gao, Bruce Z; Yuan, X-C

    2016-01-01

    Viscosity coefficients of microfluids—Newtonian and non-Newtonian—were explored through the rotational motion of a particle trapped by optical tweezers in a microflute. Unlike conventional methods based on viscometers, our microfluidic system employs samples of less than 30 µl to complete a measurement. Viscosity coefficients of ethanol and fetal bovine serum, as typical examples of Newtonian and non-Newtonian fluids, were obtained experimentally, and found to be in excellent agreement with theoretical predictions. Additionally, a practical application to a DNA solution with incremental ethidium bromide content was employed and the results are consistent with clinical data, indicating that our system provides a potentially important complementary tool for use in such biological and medical applications. PMID:27087769

  17. Laser-induced fluorescence imaging system for protein separations in microfluidic devices

    NASA Astrophysics Data System (ADS)

    Das, Champak; Stoyanov, Alexander; Fredrickson, Carl; Tran-Son-Tay, Roger; Fan, Zhonghui H.

    2004-12-01

    This paper describes a laser-induced fluorescence (LIF) detection system for imaging proteins separated in a microfluidic device. The diameter of a laser beam is first increased through a beam expander, and subsequently focused into a line using a cylindrical lens. The resultant laser line is used to image an entire capillary or channel in which protein separation took place. The fluorescence emission is collected with a cooled, scientific grade charge-coupled device (CCD) camera. The detection limit was determined using a series of concentrations of fluorescein solutions. The temporal and spatial effects of photobleaching from laser irradiation were analyzed and the parameters to reduce the effect of photobleaching are discussed. We used the imaging system to demonstrate rapid analysis of proteins using isoelectric focusing.

  18. Detection of a live cell in a microfluidic system by scanning capacitance microscopy

    NASA Astrophysics Data System (ADS)

    Sung, S. Y.; Yi, I. J.; Choi, Y. J.; Kim, J. Y.; Kim, Y. S.; Kang, C. J.

    2007-03-01

    In recent years, many studies on the biosensors using a microfluidic system have been performed. The system fabricated with polydimethylsiloxane (PDMS) has many advantages such that it is portable, disposable, cost effective, and automatable. Scanning capacitance microscope (SCM) that has a good capacitance pickup sensor attached to an atomic force microscope (AFM) is capable of measuring the capacitance variation with a resolution of better than 10-18F/V between a conducting tip and the sample. In this work, we present possibility of SCM as a biosensor by measuring a live cell which flows in the microchannel. By measuring the consecutive capacitance line profiles of a cell, which represent the charge distribution of a cell surface resulting from the ion channel or cell activity, we can get more information on the cell analysis and provide one solution for the realization of a lab-on-a-chip.

  19. 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.

  20. An integrated microfluidic system for measurement of glycated hemoglobin levels by using an aptamer-antibody assay on magnetic beads.

    PubMed

    Chang, Ko-Wei; Li, Jinglun; Yang, Ching-Hsuan; Shiesh, Shu-Chu; Lee, Gwo-Bin

    2015-06-15

    Blood glycated hemoglobin (HbA1c), reflecting the average blood glucose level in the proceeding 2-3 months, is recommended for screening/diagnosing and patient management of diabetes. However, accurate measurement of the HbA1c level at the point of care is hampered by costly, large-scale instruments (such as high-performance liquid chromatography) or reagent instability of classical immunologic methods, which involve antibody-based immunoturbidimetry. In this work, an integrated microfluidic system using aptamer-based testing to measure HbA1c in blood samples is therefore presented. This measuring system used nucleic-acid aptamers that exhibited high sensitivity and high specificity for hemoglobin and HbA1c to perform a stable and robust testing. The compact microfluidic system consumed less samples and reagents and significantly shortened the detection time. Combining the advantages of microfluidics and aptamers, this integrated microsystem presents a promising tool for accurate and point-of-case HbA1c detection. To demonstrate its clinical utility, whole blood samples with clinically-relevant concentrations of HbA1c and Hb were automatically measured on the integrated microfluidic system. Experimental data showed that the developed aptamer-based microfluidic system is capable of detecting HbA1c and Hb with a good linear response. The entire process was completed within 25 min. The aptamer-antibody on-chip sandwich immunoassay may be further refined to allow diabetes screening and diagnosis at lower cost and earlier phase to minimize the risk of diabetic complications.

  1. Microfluidics: reframing biological enquiry.

    PubMed

    Duncombe, Todd A; Tentori, Augusto M; Herr, Amy E

    2015-09-01

    The underlying physical properties of microfluidic tools have led to new biological insights through the development of microsystems that can manipulate, mimic and measure biology at a resolution that has not been possible with macroscale tools. Microsystems readily handle sub-microlitre volumes, precisely route predictable laminar fluid flows and match both perturbations and measurements to the length scales and timescales of biological systems. The advent of fabrication techniques that do not require highly specialized engineering facilities is fuelling the broad dissemination of microfluidic systems and their adaptation to specific biological questions. We describe how our understanding of molecular and cell biology is being and will continue to be advanced by precision microfluidic approaches and posit that microfluidic tools - in conjunction with advanced imaging, bioinformatics and molecular biology approaches - will transform biology into a precision science.

  2. Development of a pneumatically driven active cover lid for multi-well microplates for use in perfusion three-dimensional cell culture

    PubMed Central

    Huang, Song-Bin; Chou, Dean; Chang, Yu-Han; Li, Ke-Cing; Chiu, Tzu-Keng; Ventikos, Yiannis; Wu, Min-Hsien

    2015-01-01

    Before microfluidic-based cell culture models can be practically utilized for bioassays, there is a need for a transitional cell culture technique that can improve conventional cell culture models. To address this, a hybrid cell culture system integrating an active cover lid and a multi-well microplate was proposed to achieve perfusion 3-D cell culture. In this system, a microfluidic-based pneumatically-driven liquid transport mechanism was integrated into the active cover lid to realize 6-unit culture medium perfusion. Experimental results revealed that the flow of culture medium could be pneumatically driven in a flow-rate uniform manner. We used the system to successfully perform a perfusion 3-D cell culture of mesenchymal stem cells (MSCs) for up to 16 days. Moreover, we investigated the effects of various cell culture models on the physiology of MSCs. The physiological nature of MSCs can vary with respect to the cell culture model used. Using the perfusion 3-D cell culture format might affect the proliferation and osteogenic differentiation of MSCs. Overall, we have developed a cell culture system that can achieve multi-well microplate-based perfusion 3-D cell culture in an efficient, cost-effective, and user-friendly manner. These features could facilitate the widespread application of perfusion cell culture models for cell-based assays. PMID:26669749

  3. Development of a pneumatically driven active cover lid for multi-well microplates for use in perfusion three-dimensional cell culture.

    PubMed

    Huang, Song-Bin; Chou, Dean; Chang, Yu-Han; Li, Ke-Cing; Chiu, Tzu-Keng; Ventikos, Yiannis; Wu, Min-Hsien

    2015-12-16

    Before microfluidic-based cell culture models can be practically utilized for bioassays, there is a need for a transitional cell culture technique that can improve conventional cell culture models. To address this, a hybrid cell culture system integrating an active cover lid and a multi-well microplate was proposed to achieve perfusion 3-D cell culture. In this system, a microfluidic-based pneumatically-driven liquid transport mechanism was integrated into the active cover lid to realize 6-unit culture medium perfusion. Experimental results revealed that the flow of culture medium could be pneumatically driven in a flow-rate uniform manner. We used the system to successfully perform a perfusion 3-D cell culture of mesenchymal stem cells (MSCs) for up to 16 days. Moreover, we investigated the effects of various cell culture models on the physiology of MSCs. The physiological nature of MSCs can vary with respect to the cell culture model used. Using the perfusion 3-D cell culture format might affect the proliferation and osteogenic differentiation of MSCs. Overall, we have developed a cell culture system that can achieve multi-well microplate-based perfusion 3-D cell culture in an efficient, cost-effective, and user-friendly manner. These features could facilitate the widespread application of perfusion cell culture models for cell-based assays.

  4. Development of a pneumatically driven active cover lid for multi-well microplates for use in perfusion three-dimensional cell culture

    NASA Astrophysics Data System (ADS)

    Huang, Song-Bin; Chou, Dean; Chang, Yu-Han; Li, Ke-Cing; Chiu, Tzu-Keng; Ventikos, Yiannis; Wu, Min-Hsien

    2015-12-01

    Before microfluidic-based cell culture models can be practically utilized for bioassays, there is a need for a transitional cell culture technique that can improve conventional cell culture models. To address this, a hybrid cell culture system integrating an active cover lid and a multi-well microplate was proposed to achieve perfusion 3-D cell culture. In this system, a microfluidic-based pneumatically-driven liquid transport mechanism was integrated into the active cover lid to realize 6-unit culture medium perfusion. Experimental results revealed that the flow of culture medium could be pneumatically driven in a flow-rate uniform manner. We used the system to successfully perform a perfusion 3-D cell culture of mesenchymal stem cells (MSCs) for up to 16 days. Moreover, we investigated the effects of various cell culture models on the physiology of MSCs. The physiological nature of MSCs can vary with respect to the cell culture model used. Using the perfusion 3-D cell culture format might affect the proliferation and osteogenic differentiation of MSCs. Overall, we have developed a cell culture system that can achieve multi-well microplate-based perfusion 3-D cell culture in an efficient, cost-effective, and user-friendly manner. These features could facilitate the widespread application of perfusion cell culture models for cell-based assays.

  5. Multi-scale Properties and Processes in Hierarchically-Structured Organic-Inorganic Solids and Surface-Based Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Messinger, Robert James

    Hierarchically-structured materials and surface-based microfluidic systems exhibit diverse properties that are inherently multi-scale in origin. In particular, different molecular, mesoscopic, and micron-scale properties and processes are often correlated and collectively account for many properties of interest, such as bulk catalytic activities or electrokinetic flow rates. However, such properties and processes often exhibit complex relationships over the different length scales that are not well understood, and consequently, difficult to control. Establishing correlations between them has been challenging, in part due to the difficulty of rigorously characterizing complex, heterogeneous materials and surface-based microfluidic experiments over multiple length scales, particularly at the molecular and mesoscopic levels. Herein, new multi-scale understanding and correlations have been established for different hierarchically-structured organic-inorganic solids or surface-based microfluidic systems, enabling control of material or device properties over discrete length scales. The molecular-level compositions, structures, interactions, and dynamics have been measured in diverse hierarchically-structured materials, such as mesostructured zeolites, mesostructured organosilicas, and organosiloxane foams, and subsequently correlated with their meso- and macroscopic material structures and properties. The results reveal new insights on the molecular-level interactions that govern their syntheses, the resulting local compositions and material structures, and the relationships among material properties over multiple characteristic length scales. Multi-dimensional solid-state nuclear magnetic resonance (NMR) spectroscopy is a cornerstone of these investigations, which enables correlative measurements in multiple frequency dimensions of the through-space or through-bond interactions between the constituent nuclei within the different materials. Other multi

  6. Dual-purpose laser irradiation and perfusion testing system for in-vitro experiments using cultured trabecular meshwork endothelial cells

    NASA Astrophysics Data System (ADS)

    Rivera, Brian K.; Roberts, Cynthia J.; Weber, Paul A.

    1998-06-01

    The means by which Argon laser trabeculoplasty (ALT) lowers intraocular pressure (IOP) is a matter of debate. Mechanical and biological laser-tissue interaction theories have been proposed. To investigate the effect laser irradiation has upon the aqueous outflow facility of trabecular meshwork (TM) cells, a suitable in-vitro model is required. Therefore the purpose of this study was to design, construct, and validate a laser irradiation and perfusion testing apparatus. The system was designed to utilize cultured TM cells seeded onto filter supports. Outflow facility will be quantified by calculating the hydraulic conductivity of the monolayer. An appropriate filter support was located, and its perfusion characteristics determined using water. Afterwards, the steady state perfusion flow rate of the filter was ascertained to be 0.096 plus or minus 0.008 ml/min when culture medium is used. Following these tests a single, baseline perfusion experiment was conducted using a TM cell monolayer. Analysis of the data produced a baseline hydraulic conductivity of 0.673 plus or minus 0.076 (mu) l/min/mm Hg/cm2, well within the range found in previous reports. A dual purpose, in vitro-cellular perfusion and laser irradiation testing apparatus has been developed, tested and validates using known baseline cellular perfusion and laser irradiation testing apparatus has been developed, tested, and validated using known baseline cellular perfusion values. Future experiments will be conducted to verify these initial findings, and further experiments will be conducted using Argon laser irradiation. The response of the TM cell monolayer will then be compared to the baseline figures.

  7. An integrated environmental perfusion chamber and heating system for long-term, high resolution imaging of living cells.

    PubMed

    Hing, W A; Poole, C A; Jensen, C G; Watson, M

    2000-08-01

    This communication presents the design and application of an integrated environmental perfusion chamber and stage heating blanket suitable for time-lapse video microscopy of living cells. The system consists of two independently regulated components: a perfusion chamber suitable for the maintenance of cell viability and the variable delivery of environmental factors, and a separate heating blanket to control the temperature of the microscope stage and limit thermal conduction from the perfusion chamber. Two contrasting experiments are presented to demonstrate the versatility of the system. One long-term sequence illustrates the behaviour of cells exposed to ceramic fibres. The other shows the shrinking response of cultured articular cartilage chondrons under dynamic hyper-osmotic conditions designed to simulate joint loading. The chamber is simple in design, economical to produce and permits long-term examination of dynamic cellular behaviour while satisfying the fundamental requirements for the maintenance of environmental factors that influence cell viability.

  8. A microfluidic platform for precision small-volume sample processing and its use to size separate biological particles with an acoustic microdevice [Precision size separation of biological particles in small-volume samples by an acoustic microfluidic system

    SciTech Connect

    Fong, Erika J.; Huang, Chao; Hamilton, Julie; Benett, William J.; Bora, Mihail; Burklund, Alison; Metz, Thomas R.; Shusteff, Maxim

    2015-11-23

    Here, a major advantage of microfluidic devices is the ability to manipulate small sample volumes, thus reducing reagent waste and preserving precious sample. However, to achieve robust sample manipulation it is necessary to address device integration with the macroscale environment. To realize repeatable, sensitive particle separation with microfluidic devices, this protocol presents a complete automated and integrated microfluidic platform that enables precise processing of 0.15–1.5 ml samples using microfluidic devices. Important aspects of this system include modular device layout and robust fixtures resulting in reliable and flexible world to chip connections, and fully-automated fluid handling which accomplishes closed-loop sample collection, system cleaning and priming steps to ensure repeatable operation. Different microfluidic devices can be used interchangeably with this architecture. Here we incorporate an acoustofluidic device, detail its characterization, performance optimization, and demonstrate its use for size-separation of biological samples. By using real-time feedback during separation experiments, sample collection is optimized to conserve and concentrate sample. Although requiring the integration of multiple pieces of equipment, advantages of this architecture include the ability to process unknown samples with no additional system optimization, ease of device replacement, and precise, robust sample processing.

  9. A microfluidic platform for precision small-volume sample processing and its use to size separate biological particles with an acoustic microdevice [Precision size separation of biological particles in small-volume samples by an acoustic microfluidic system

    DOE PAGES

    Fong, Erika J.; Huang, Chao; Hamilton, Julie; ...

    2015-11-23

    Here, a major advantage of microfluidic devices is the ability to manipulate small sample volumes, thus reducing reagent waste and preserving precious sample. However, to achieve robust sample manipulation it is necessary to address device integration with the macroscale environment. To realize repeatable, sensitive particle separation with microfluidic devices, this protocol presents a complete automated and integrated microfluidic platform that enables precise processing of 0.15–1.5 ml samples using microfluidic devices. Important aspects of this system include modular device layout and robust fixtures resulting in reliable and flexible world to chip connections, and fully-automated fluid handling which accomplishes closed-loop sample collection,more » system cleaning and priming steps to ensure repeatable operation. Different microfluidic devices can be used interchangeably with this architecture. Here we incorporate an acoustofluidic device, detail its characterization, performance optimization, and demonstrate its use for size-separation of biological samples. By using real-time feedback during separation experiments, sample collection is optimized to conserve and concentrate sample. Although requiring the integration of multiple pieces of equipment, advantages of this architecture include the ability to process unknown samples with no additional system optimization, ease of device replacement, and precise, robust sample processing.« less

  10. 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.

  11. A microfluidic detection system based upon a surface immobilized biobarcode assay.

    PubMed

    Goluch, Edgar D; Stoeva, Savka I; Lee, Jae-Seung; Shaikh, Kashan A; Mirkin, Chad A; Liu, Chang

    2009-04-15

    The biobarcode assay (BCA) is capable of achieving low detection limits and high specificity for both protein and DNA targets. The realization of a BCA in a microfluidic format presents unique opportunities and challenges. In this work, we describe a modified form of the BCA called the surface immobilized biobarcode assay (SI-BCA). The SI-BCA employs microchannel walls functionalized with antibodies that bind with the intended targets. Compared with the conventional BCA, it reduces the system complexity and results in shortened process time, which is attributed to significantly reduced diffusion times in the micro-scale channels. Raw serum samples, without any pretreatment, were evaluated with this technique. Prostate specific antigen in the samples was detected at concentrations ranging from 40 pM to 40 fM. The detection limit of the assay using buffer samples is 10 fM. The entire assay, from sample injection to final data analysis was completed in 80 min.

  12. Efficient Nanoporous Silicon Membranes for Integrated Microfluidic Separation and Sensing Systems

    SciTech Connect

    Ileri, N; L?tant, S E; Britten, J; Nguyen, H; Larson, C; Zaidi, S; Palazoglu, A; Faller, R; Tringe, J W; Stroeve, P

    2009-04-06

    Nanoporous devices constitute emerging platforms for selective molecule separation and sensing, with great potential for high throughput and economy in manufacturing and operation. Acting as mass transfer diodes similar to a solid-state device based on electron conduction, conical pores are shown to have superior performance characteristics compared to traditional cylindrical pores. Such phenomena, however, remain to be exploited for molecular separation. Here we present performance results from silicon membranes created by a new synthesis technique based on interferometric lithography. This method creates millimeter sized planar arrays of uniformly tapered nanopores in silicon with pore diameter 100 nm or smaller, ideally-suited for integration into a multi-scale microfluidic processing system. Molecular transport properties of these devices are compared against state-of-the-art polycarbonate track etched (PCTE) membranes. Mass transfer rates of up to fifteen-fold greater than commercial sieve technology are obtained. Complementary results from molecular dynamics simulations on molecular transport are reported.

  13. A Microfluidic System for Studying Ageing and Dynamic Single-Cell Responses in Budding Yeast

    PubMed Central

    Bakker, Elco; Smith, Stewart; Swain, Peter S.

    2014-01-01

    Recognition of the importance of cell-to-cell variability in cellular decision-making and a growing interest in stochastic modeling of cellular processes has led to an increased demand for high density, reproducible, single-cell measurements in time-varying surroundings. We present ALCATRAS (A Long-term Culturing And TRApping System), a microfluidic device that can quantitatively monitor up to 1000 cells of budding yeast in a well-defined and controlled environment. Daughter cells are removed by fluid flow to avoid crowding allowing experiments to run for over 60 hours, and the extracellular media may be changed repeatedly and in seconds. We illustrate use of the device by measuring ageing through replicative life span curves, following the dynamics of the cell cycle, and examining history-dependent behaviour in the general stress response. PMID:24950344

  14. Capillary electrophoresis-electrochemistry microfluidic system for the determination of organic peroxides.

    PubMed

    Wang, Joseph; Escarpa, Alberto; Pumera, Martin; Feldman, Jason

    2002-04-05

    A microfluidic analytical system for the separation and detection of organic peroxides, based on a microchip capillary electrophoresis device with an integrated amperometric detector, was developed. The new microsystem relies on the reductive detection of both organic acid peroxides and hydroperoxides at -700 mV (vs. Ag wire/AgCl). Factors influencing the separation and detection processes were examined and optimized. The integrated microsystem offers rapid measurements (within 130 s) of these organic-peroxide compounds, down to micromolar levels. A highly stable response for repetitive injections (RSD 0.35-3.12%; n = 12) reflects the negligible electrode passivation. Such a "lab-on-a-chip" device should be attractive for on-site analysis of organic peroxides, as desired for environmental screening and industrial monitoring.

  15. Examination of glass-silicon and glass-glass bonding techniques for microfluidic systems

    SciTech Connect

    Raley, N.F.; Davidson, J.C.; Balch, J.W.

    1995-10-23

    We report here on the results of experiments concerning particular bonding processes potentially useful for ultimate miniaturization of microfluidic systems. Direct anodic bonding of continuous thin pyrex glass of 250 {mu}m thickness to silicon substrates gives multiple, large voids in the glass. Etchback of thick glass of 1200 {mu}m thickness bonded to silicon substrates gives thin continuous glass layers of 189 {mu}m thickness without voids over areas of 5 cm {times} 12 cm. Glass was also successfully bonded to glass by thermal bonding at 800{degrees}C over a 5 cm {times} 7 cm area. Anticipated applications include microfabricated DNA sequencing, flow injection analysis, and liquid and gas chromatography microinstruments.

  16. Capillary electrophoresis-electrochemistry microfluidic system for the determination of organic peroxides

    NASA Technical Reports Server (NTRS)

    Wang, Joseph; Escarpa, Alberto; Pumera, Martin; Feldman, Jason; Svehla, D. (Principal Investigator)

    2002-01-01

    A microfluidic analytical system for the separation and detection of organic peroxides, based on a microchip capillary electrophoresis device with an integrated amperometric detector, was developed. The new microsystem relies on the reductive detection of both organic acid peroxides and hydroperoxides at -700 mV (vs. Ag wire/AgCl). Factors influencing the separation and detection processes were examined and optimized. The integrated microsystem offers rapid measurements (within 130 s) of these organic-peroxide compounds, down to micromolar levels. A highly stable response for repetitive injections (RSD 0.35-3.12%; n = 12) reflects the negligible electrode passivation. Such a "lab-on-a-chip" device should be attractive for on-site analysis of organic peroxides, as desired for environmental screening and industrial monitoring.

  17. A microfluidic in vitro system for the quantitative study of the stomach mucus barrier function.

    PubMed

    Li, Leon; Lieleg, Oliver; Jang, Sae; Ribbeck, Katharina; Han, Jongyoon

    2012-10-21

    In the stomach, a layer of gastric mucus protects the epithelial cells of the stomach wall against damage by the acidic digestive juices in the gastric lumen. Despite considerable research, the biophysical mechanisms for this acid barrier are not understood. We present an in vitro microfluidic tool to characterize the stomach acid barrier, in which purified mucin polymers are "secreted" against an acidic zone on chip, mimicking the in vivo secretion of gastric mucus into an acidic stomach lumen. This device reconstitutes both the H(+) concentration gradient and outward flow environment of the mucus layer in vivo. Our experiments demonstrate that a continuously secreted mucin layer hinders acid diffusion, suggesting novel insights into the barrier role of mucins. More broadly, our system may serve as a platform tool for studying the barrier functions provided by mucus layers in the body and for studying mucus drug interactions.

  18. The μSCAPE System: 3-Dimensional Profiling of Microfluidic Architectural Features Using a Flatbed Scanner.

    PubMed

    Xu, Kerui; Liu, Qian; Jackson, Kimberly R; Landers, James P

    2016-02-29

    We developed a microfluidic scanner-based profile exploration system, μSCAPE, capable of generating high resolution 3D profiles of microstructure architecture in a variety of transparent substrates. The profile is obtained by scanning the dye-filled microstructure followed by absorbance calculation and the reconstruction of the optical length at each point. The power of the method was demonstrated in (1) the inspection of the variation of the cross-section of laser-ablated PDMS channel; (2) the volume of PeT chamber; and (3) the population distribution of the volumes of the micro wells in HF-etched glass and laser-ablated PDMS. The reported methods features low equipment-cost, convenient operation and large field of view (FOV), and has revealed unreported quality parameters of the tested microstructures.

  19. The μSCAPE System: 3-Dimensional Profiling of Microfluidic Architectural Features Using a Flatbed Scanner

    PubMed Central

    Xu, Kerui; Liu, Qian; Jackson, Kimberly R.; Landers, James P.

    2016-01-01

    We developed a microfluidic scanner-based profile exploration system, μSCAPE, capable of generating high resolution 3D profiles of microstructure architecture in a variety of transparent substrates. The profile is obtained by scanning the dye-filled microstructure followed by absorbance calculation and the reconstruction of the optical length at each point. The power of the method was demonstrated in (1) the inspection of the variation of the cross-section of laser-ablated PDMS channel; (2) the volume of PeT chamber; and (3) the population distribution of the volumes of the micro wells in HF-etched glass and laser-ablated PDMS. The reported methods features low equipment-cost, convenient operation and large field of view (FOV), and has revealed unreported quality parameters of the tested microstructures. PMID:26924294

  20. Capillary electrophoresis-electrochemistry microfluidic system for the determination of organic peroxides

    NASA Technical Reports Server (NTRS)

    Wang, Joseph; Escarpa, Alberto; Pumera, Martin; Feldman, Jason; Svehla, D. (Principal Investigator)

    2002-01-01

    A microfluidic analytical system for the separation and detection of organic peroxides, based on a microchip capillary electrophoresis device with an integrated amperometric detector, was developed. The new microsystem relies on the reductive detection of both organic acid peroxides and hydroperoxides at -700 mV (vs. Ag wire/AgCl). Factors influencing the separation and detection processes were examined and optimized. The integrated microsystem offers rapid measurements (within 130 s) of these organic-peroxide compounds, down to micromolar levels. A highly stable response for repetitive injections (RSD 0.35-3.12%; n = 12) reflects the negligible electrode passivation. Such a "lab-on-a-chip" device should be attractive for on-site analysis of organic peroxides, as desired for environmental screening and industrial monitoring.

  1. Label-free high-throughput detection and content sensing of individual droplets in microfluidic systems.

    PubMed

    Yesiloz, Gurkan; Boybay, Muhammed Said; Ren, Carolyn L

    2015-10-21

    This study reports a microwave-microfluidics integrated approach capable of performing droplet detection at high-throughput as well as content sensing of individual droplets without chemical or physical intrusion. The sensing system consists of a custom microwave circuitry and a spiral-shaped microwave resonator that is integrated with microfluidic chips where droplets are generated. The microwave circuitry is very cost effective by using off-the-shelf components only. It eliminates the need for bulky benchtop equipment, and provides a compact, rapid and sensitive tool compatible for Lab-on-a-Chip (LOC) platforms. To evaluate the resonator's sensing capability, it was first applied to differentiate between single-phase fluids which are aqueous solutions with different concentrations of glucose and potassium chloride respectively by measuring its reflection coefficient as a function of frequency. The minimum concentration assessed was 0.001 g ml(-1) for potassium chloride and 0.01 g ml(-1) for glucose. In the droplet detection experiments, it is demonstrated that the microwave sensor is able to detect droplets generated at as high throughput as 3.33 kHz. Around two million droplets were counted over a period of ten minutes without any missing. For droplet sensing experiments, pairs of droplets that were encapsulated with biological materials were generated alternatively in a double T-junction configuration and clearly identified by the microwave sensor. The sensed biological materials include fetal bovine serum, penicillin antibiotic mixture, milk (2% mf) and d-(+)-glucose. This system has significant advantages over optical detection methods in terms of its cost, size and compatibility with LOC settings and also presents significant improvements over other electrical-based detection techniques in terms of its sensitivity and throughput.

  2. LPS from bovine serum albumin drives TNF-α release during ex-vivo placenta perfusion experiments, contaminates the perfusion system but can be effectively removed by oxidative cleaning.

    PubMed

    Vasanthan, T; Rochow, N; Mian, F; Codini, T; DeFrance, B; Fusch, G; Samiee-Zafarghandy, S; Fusch, C

    2014-12-01

    The dual ex-vivo perfusion of human placental tissue is useful to study inflammatory pathways. We found significant TNF-α release in negative controls similar in concentration to lipopolysaccharide (LPS) stimulated placentas. The aim of the current study was to (i) identify sources driving TNF-α release and (ii) develop an approach to control for it. (i) To determine sources leading to TNF-α release, solutions frequently circulated through the perfusion system and perfusion media with different bovine serum albumin (BSA) quality were exposed to mouse macrophage cell lines (RAW264.7) and subsequently measured for TNF-α expression. (ii) To assess memory effects and validate cleaning procedures, sham perfusion experiments were conducted either in the presence or absence of exogenous LPS, in new tubing that was contaminated, cleaned and analyzed for the effectiveness of LPS removal. Oxidative and acid-base cleaning were tested for their effectiveness to reduce LPS contamination. TNF-α release, observed in negative control experiments, was attributed to the use of LPS-contaminated BSA as well as inadequate cleaning of the perfusion system. Once introduced in the perfusion system, LPS accumulated and created a memory effect. Oxidative but not acid-base depyrogenation effectively reduced LPS levels to concentrations that were in accordance with FDA guidelines (<0.5 EU/mL) for medical equipment redeemed appropriate for re-use. LPS contamination of the placenta perfusion model could have confounding effects on experimental outcomes leading to misinterpretation of data. To circumvent LPS contamination LPS-free BSA and oxidative depyrogenation cleaning techniques should be implemented in future placental perfusion studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Passive microfluidic array card and reader

    SciTech Connect

    Dugan, Lawrence Christopher; Coleman, Matthew A

    2011-08-09

    A microfluidic array card and reader system for analyzing a sample. The microfluidic array card includes a sample loading section for loading the sample onto the microfluidic array card, a multiplicity of array windows, and a transport section or sections for transporting the sample from the sample loading section to the array windows. The microfluidic array card reader includes a housing, a receiving section for receiving the microfluidic array card, a viewing section, and a light source that directs light to the array window of the microfluidic array card and to the viewing section.

  4. A Reduced Order Model for Whole-Chip Thermal Analysis of Microfluidic Lab-on-a-Chip Systems

    PubMed Central

    Wang, Yi; Song, Hongjun; Pant, Kapil

    2013-01-01

    This paper presents a Krylov subspace projection-based Reduced Order Model (ROM) for whole microfluidic chip thermal analysis, including conjugate heat transfer. Two key steps in the reduced order modeling procedure are described in detail, including (1) the acquisition of a 3D full-scale computational model in the state-space form to capture the dynamic thermal behavior of the entire microfluidic chip; and (2) the model order reduction using the Block Arnoldi algorithm to markedly lower the dimension of the full-scale model. Case studies using practically relevant thermal microfluidic chip are undertaken to establish the capability and to evaluate the computational performance of the reduced order modeling technique. The ROM is compared against the full-scale model and exhibits good agreement in spatiotemporal thermal profiles (<0.5% relative error in pertinent time scales) and over three orders-of-magnitude acceleration in computational speed. The salient model reusability and real-time simulation capability renders it amenable for operational optimization and in-line thermal control and management of microfluidic systems and devices. PMID:24443647

  5. In vivo preclinical verification of a multimodal diffuse reflectance and correlation spectroscopy system for sensing tissue perfusion

    NASA Astrophysics Data System (ADS)

    Pakela, Julia M.; Lee, Seung Yup; Hedrick, Taylor L.; Vishwanath, Karthik; Helton, Michael C.; Chung, Yooree G.; Kolodziejski, Noah J.; Staples, Christopher J.; McAdams, Daniel R.; Fernandez, Daniel E.; Christian, James F.; O'Reilly, Jameson; Farkas, Dana; Ward, Brent B.; Feinberg, Stephen E.; Mycek, Mary-Ann

    2017-02-01

    In reconstructive surgery, impeded blood flow in microvascular free flaps due to a compromise in arterial or venous patency secondary to blood clots or vessel spasms can rapidly result in flap failures. Thus, the ability to detect changes in microvascular free flaps is critical. In this paper, we report progress on in vivo pre-clinical testing of a compact, multimodal, fiber-based diffuse correlation and reflectance spectroscopy system designed to quantitatively monitor tissue perfusion in a porcine model's surgically-grafted free flap. We also describe the device's sensitivity to incremental blood flow changes and discuss the prospects for continuous perfusion monitoring in future clinical translational studies.

  6. Engineering anastomosis between living capillary networks and endothelial cell-lined microfluidic channels.

    PubMed

    Wang, Xiaolin; Phan, Duc T T; Sobrino, Agua; George, Steven C; Hughes, Christopher C W; Lee, Abraham P

    2016-01-21

    This paper reports a method for generating an intact and perfusable microvascular network that connects to microfluidic channels without appreciable leakage. This platform incorporates different stages of vascular development including vasculogenesis, endothelial cell (EC) lining, sprouting angiogenesis, and anastomosis in sequential order. After formation of a capillary network inside the tissue chamber via vasculogenesis, the adjacent microfluidic channels are lined with a monolayer of ECs, which then serve as the high-pressure input ("artery") and low pressure output ("vein") conduits. To promote a tight interconnection between the artery/vein and the capillary network, sprouting angiogenesis is induced, which promotes anastomosis of the vasculature inside the tissue chamber with the EC lining along the microfluidic channels. Flow of fluorescent microparticles confirms the perfusability of the lumenized microvascular network, and minimal leakage of 70 kDa FITC-dextran confirms physiologic tightness of the EC junctions and completeness of the interconnections between artery/vein and the capillary network. This versatile device design and its robust construction methodology establish a physiological transport model of interconnected perfused vessels from artery to vascularized tissue to vein. The system has utility in a wide range of organ-on-a-chip applications as it enables the physiological vascular interconnection of multiple on-chip tissue constructs that can serve as disease models for drug screening.

  7. Simple, Expendable, 3D-Printed Microfluidic Systems for Sample Preparation of Petroleum.

    PubMed

    Kataoka, Érica M; Murer, Rui C; Santos, Jandyson M; Carvalho, Rogério M; Eberlin, Marcos N; Augusto, Fabio; Poppi, Ronei J; Gobbi, Angelo L; Hantao, Leandro W

    2017-03-21

    In this study, we introduce a simple protocol to manufacture disposable, 3D-printed microfluidic systems for sample preparation of petroleum. This platform is produced with a consumer-grade 3D-printer, using fused deposition modeling. Successful incorporation of solid-phase extraction (SPE) to microchip was ensured by facile 3D element integration using proposed approach. This 3D-printed μSPE device was applied to challenging matrices in oil and gas industry, such as crude oil and oil-brine emulsions. Case studies investigated important limitations of nonsilicon and nonglass microchips, namely, resistance to nonpolar solvents and conservation of sample integrity. Microfluidic features remained fully functional even after prolonged exposure to nonpolar solvents (20 min). Also, 3D-printed μSPE devices enabled fast emulsion breaking and solvent deasphalting of petroleum, yielding high recovery values (98%) without compromising maltene integrity. Such finding was ascertained by high-resolution molecular analyses using comprehensive two-dimensional gas chromatography and gas chromatography/mass spectrometry by monitoring important biomarker classes, such as C10 demethylated terpanes, ααα-steranes, and monoaromatic steroids. 3D-Printed chips enabled faster and reliable preparation of maltenes by exhibiting a 10-fold reduction in sample processing time, compared to the reference method. Furthermore, polar (oxygen-, nitrogen-, and sulfur-containing) analytes found in low-concentrations were analyzed by Fourier transform ion cyclotron resonance mass spectrometry. Analysis results demonstrated that accurate characterization may be accomplished for most classes of polar compounds, except for asphaltenes, which exhibited lower recoveries (82%) due to irreversible adsorption to sorbent phase. Therefore, 3D-printing is a compelling alternative to existing microfabrication solutions, as robust devices were easy to prepare and operate.

  8. Evaluation of mechanical and morphologic features of PLLA membranes as supports for perfusion cells culture systems.

    PubMed

    Montesanto, S; Brucato, V; La Carrubba, V

    2016-12-01

    Porous biodegradable PLLA membranes, which can be used as supports for perfusion cell culture systems were designed, developed and characterized. PLLA membranes were prepared via diffusion induced phase separation (DIPS). A glass slab was coated with a binary PLLA-dioxane solution (8wt.% PLLA) via dip coating, then pool immersed in two subsequent coagulation baths, and finally dried in a humidity-controlled environment. Surface and mechanical properties were evaluated by measuring pore size, porosity via scanning electron microscopy, storage modulus, loss modulus and loss angle by using a dynamic mechanical analysis (DMA). Cell adhesion assays on different membrane surfaces were also performed by using a standard count method. Results provide new insights into the foaming methods for producing polymeric membranes and supply indications on how to optimise the fabrication parameters to design membranes for tissue cultures and regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Repair of Segmental Bone Defect Using Totally Vitalized Tissue Engineered Bone Graft by a Combined Perfusion Seeding and Culture System

    PubMed Central

    Feng, Ya-Fei; Li, Xiang; Hu, Yun-Yu; Wang, Zhen; Ma, Zhen-Sheng; Lei, Wei

    2014-01-01

    Background The basic strategy to construct tissue engineered bone graft (TEBG) is to combine osteoblastic cells with three dimensional (3D) scaffold. Based on this strategy, we proposed the “Totally Vitalized TEBG” (TV-TEBG) which was characterized by abundant and homogenously distributed cells with enhanced cell proliferation and differentiation and further investigated its biological performance in repairing segmental bone defect. Methods In this study, we constructed the TV-TEBG with the combination of customized flow perfusion seeding/culture system and β-tricalcium phosphate (β-TCP) scaffold fabricated by Rapid Prototyping (RP) technique. We systemically compared three kinds of TEBG constructed by perfusion seeding and perfusion culture (PSPC) method, static seeding and perfusion culture (SSPC) method, and static seeding and static culture (SSSC) method for their in vitro performance and bone defect healing efficacy with a rabbit model. Results Our study has demonstrated that TEBG constructed by PSPC method exhibited better biological properties with higher daily D-glucose consumption, increased cell proliferation and differentiation, and better cell distribution, indicating the successful construction of TV-TEBG. After implanted into rabbit radius defects for 12 weeks, PSPC group exerted higher X-ray score close to autograft, much greater mechanical property evidenced by the biomechanical testing and significantly higher new bone formation as shown by histological analysis compared with the other two groups, and eventually obtained favorable healing efficacy of the segmental bone defect that was the closest to autograft transplantation. Conclusion This study demonstrated the feasibility of TV-TEBG construction with combination of perfusion seeding, perfusion culture and RP technique which exerted excellent biological properties. The application of TV-TEBG may become a preferred candidate for segmental bone defect repair in orthopedic and maxillofacial

  10. A Microfluidic Device for Continuous Sensing of Systemic Acute Toxicants in Drinking Water

    PubMed Central

    Zhao, Xinyan; Dong, Tao

    2013-01-01

    A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety. PMID:24300075

  11. A microfluidic device for continuous sensing of systemic acute toxicants in drinking water.

    PubMed

    Zhao, Xinyan; Dong, Tao

    2013-12-03

    A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety.

  12. Perfusion and infusion for melanoma in-transit metastases in the era of effective systemic therapy.

    PubMed

    Grünhagen, Dirk J; Kroon, Hidde M; Verhoef, Cornelis

    2015-01-01

    The management of melanoma in-transit metastases (IT-mets) is challenging. For many years, the absence of effective systemic therapy has prompted physicians to focus on regional therapies for melanoma confined to the limb. The introduction of isolated limb perfusion (ILP) and isolated limb infusion (ILI) has enabled effective delivery of cytotoxic drugs in an isolated circuit, so as to overcome systemic toxicity and maximize local response. Both techniques have evolved over years and both tumor necrosis factor (TNF)-alpha-based ILP and ILI have distinct indications. The development of new systemic treatment options for patients with melanoma in the past decade has shed a new light on melanoma therapy. The present manuscript focuses on the modern role of ILI and ILP in the treatment of patients with melanoma with in-transit metastases in the era of effective systemic therapy. The response and control rates of ILI/ILP are still superior to rates achieved with systemic agents. The extent of disease in patients with stage III disease, however, warrants effective systemic treatment to prolong survival. There is great potential in combining rapid response therapy such as ILI/ILP with systemic agents for sustainable response. Trial results are eagerly awaited.

  13. A novel, compact disk-like centrifugal microfluidics system for cell lysis and sample homogenization.

    PubMed

    Kido, Horacio; Micic, Miodrag; Smith, David; Zoval, Jim; Norton, Jim; Madou, Marc

    2007-07-01

    In this paper, we present the design and characterization of a novel platform for mechanical cell lysis of even the most difficult to lyse cell types on a micro or nanoscale (maximum 70 microL total volume). The system incorporates a machined plastic circular disk assembly, magnetic field actuated microfluidics, centrifugal cells and tissue homogenizer and centrifugation system. The mechanism of tissue disruption of this novel cell homogenization apparatus derives from the relative motion of ferromagnetic metal disks and grinding matrices in a liquid medium within individual chambers of the disk in the presence of an oscillating magnetic field. The oscillation of the ferromagnetic disks or blades produces mechanical impaction and shear forces capable of disrupting cells within the chamber both by direct action of the blade and by the motion of the surrounding lysis matrix, and by motion induced vortexing of buffer fluid. Glass beads or other grinding media are integrated into each lysis chamber within the disk to enhance the transfer of energy from the oscillating metal blade to the cells. The system also achieves the centrifugal elimination of solids from each liquid sample and allows the elution of clarified supernatants via siphoning into a collection chamber fabricated into the plastic disk assembly. This article describes system design, implementation and validation of proof of concept on two samples--Escherichia coli and Saccharomyces cerevisiae representing model systems for cells that are easy and difficult to lyse, respectively.

  14. 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.

  15. Intrinsic FGF2 and FGF5 promotes angiogenesis of human aortic endothelial cells in 3D microfluidic angiogenesis system

    PubMed Central

    Seo, Ha-Rim; Jeong, Hyo Eun; Joo, Hyung Joon; Choi, Seung-Cheol; Park, Chi-Yeon; Kim, Jong-Ho; Choi, Ji-Hyun; Cui, Long-Hui; Hong, Soon Jun; Chung, Seok; Lim, Do-Sun

    2016-01-01

    The human body contains different endothelial cell types and differences in their angiogenic potential are poorly understood. We compared the functional angiogenic ability of human aortic endothelial cells (HAECs) and human umbilical vein endothelial cells (HUVECs) using a three-dimensional (3D) microfluidic cell culture system. HAECs and HUVECs exhibited similar cellular characteristics in a 2D culture system; however, in the 3D microfluidic angiogenesis system, HAECs exhibited stronger angiogenic potential than HUVECs. Interestingly, the expression level of fibroblast growth factor (FGF)2 and FGF5 under vascular endothelial growth factor (VEGF)-A stimulation was significantly higher in HAECs than in HUVECs. Moreover, small interfering RNA-mediated knockdown of FGF2 and FGF5 more significantly attenuated vascular sprouting induced from HAECs than HUVECs. Our results suggest that HAECs have greater angiogenic potential through FGF2 and FGF5 upregulation and could be a compatible endothelial cell type to achieve robust angiogenesis. PMID:27357248

  16. Perfusion circuit concepts for hollow-fiber bioreactors used as in vitro cell production systems or ex vivo bioartificial organs.

    PubMed

    Balmert, Stephen C; McKeel, Daniel; Triolo, Fabio; Gridelli, Bruno; Zeilinger, Katrin; Bornemann, Reiner; Gerlach, Jörg C

    2011-05-01

    For the development and implementation of primary human cell- and stem cell-based applications in regenerative medicine, large amounts of cells with well-defined characteristics are needed. Such cell quantities can be obtained with the use of hollow fiber-based bioreactors. While the use of such bioreactors generally requires a perfusion circuit, the configuration and complexity of such circuits is still in debate. We evaluated various circuit configurations to investigate potential perfusate volume shifts in the arterial and venous sides of the perfusion circuit, as well as in the feed and waste lines. Volume shifts with changes in flow conditions were measured with graduated bubble traps in the circuit, and perfusion pressures were measured at three points in the circuits. The results of this study demonstrate that the bioreactor perfusion circuit configuration has an effect on system pressures and volume shifts in the circuit. During operation, spikes in post-bioreactor pressures caused detrimental, potentially dangerous volume shifts in the feed and waste lines for configurations that lacked feed pumps and/or waste line check valves. Our results indicate that a more complex tubing circuit adds to safety of operation and avoids technical challenges associated with the use of large-scale hollow fiber bioreactors (e.g., for extracorporeal liver support or erythrocyte production from hematopoietic stem cells), including volume shifts and the need for a large reservoir. Finally, to ensure safe use of bioreactors, measuring pre-, intra-, and post-bioreactor pressures, and pump operation control is also advisable, which suggests the use of specifically developed bioreactor perfusion devices.

  17. Bipolar radiofrequency ablation in ex vivo bovine liver with the open-perfused system versus the cooled-wet system.

    PubMed

    Lee, Jeong Min; Han, Joon Koo; Kim, Se Hyung; Sohn, Kyu Li; Choi, Seung Hong; Choi, Byung Ihn

    2005-04-01

    The aim of this study was to investigate the efficacy of bipolar radiofrequency ablation (RFA) with the open-perfused electrode and cooled-wet electrode. Bipolar RF was applied for 20 min to the ex vivo bovine liver using either the Berchtold system with two 16-gauge open-perfused electrodes (group A, n=15) or the Radionics system with two 15-gauge cooled-wet electrodes (group B, n=15). In both groups, two electrodes were placed 3 cm apart. The ablation zone was created by the RF energy delivered together with the infusion of 5% hypertonic saline (2 ml/min). The dimension of the ablation zone, its shape and the changes in the impedance and W s of two groups during the RFA were examined and documented. The vertical diameter (Dv) along the probe, the long-axis diameter (Dl) perpendicular to the Dv in the longitudinal plane and the short-axis diameter of the ablation zone (Ds) in the transverse plane through the midpoint between the tips of two probes were measured. The mean accumulated energy output in the Radionics system was higher than in the Berchtold system (159,887.0+/-36,423 W s vs. 87,555.1+/-86,787 W s). The difference was statistically significant (P<0.05). In group A, the impedance intermittently rose to above 700 Omega during the RFA in all sessions, which led to a gradual decrease of the power output to lower than 30 W. In group B, on the other hand, the impedance did not change markedly. The mean Dv value of the coagulation necrosis in group B was significantly longer than in group A (5.0+/-0.4 cm vs. 4.3+/-0.6 cm, P<0.05). The mean Dl and Ds were 6.7+/-0.5 cm and 5.0+/-0.8 cm in group A, and 6.5+/-0.8 cm and 5.5+/-0.7 cm in group B, respectively (P>0.05). The data demonstrate that the cooled-wet electrode generates the more spherical ablation zone than the open-perfused electrode. With approximately doubled power output, the bipolar RFA with the cooled-wet electrodes induces a larger volume of tissue coagulation than with the open-perfused electrodes.

  18. Controlled perturbation of the thermodynamic equilibrium by microfluidic separation of porphyrin-based aggregates in a multi-component self-assembling system.

    PubMed

    Helmich, Floris; Meijer, E W

    2013-03-04

    In a microfluidic H-cell, a multi-component self-assembled system is brought out-of-equilibrium by changing the bimodal composition of porphyrin stacks and pyridine-capped dimers. Driven by their different diffusivities, diffusion-controlled separation in methylcyclohexane reveals different compositions when detected in-line and off-line, which demonstrates the kinetic behaviour of this metastable system. The microfluidic technique also proves to be highly equipped to determine diffusion constants of the different assemblies.

  19. Use of a High-throughput In Vitro Microfluidic System to Develop Oral Multi-species Biofilms

    PubMed Central

    Samarian, Derek S.; Jakubovics, Nicholas S.; Luo, Ting L.; Rickard, Alexander H.

    2014-01-01

    There are few high-throughput in vitro systems which facilitate the development of multi-species biofilms that contain numerous species commonly detected within in vivo oral biofilms. Furthermore, a system that uses natural human saliva as the nutrient source, instead of artificial media, is particularly desirable in order to support the expression of cellular and biofilm-specific properties that mimic the in vivo communities. We describe a method for the development of multi-species oral biofilms that are comparable, with respect to species composition, to supragingival dental plaque, under conditions similar to the human oral cavity. Specifically, this methods article will describe how a commercially available microfluidic system can be adapted to facilitate the development of multi-species oral biofilms derived from and grown within pooled saliva. Furthermore, a description of how the system can be used in conjunction with a confocal laser scanning microscope to generate 3-D biofilm reconstructions for architectural and viability analyses will be presented. Given the broad diversity of microorganisms that grow within biofilms in the microfluidic system (including Streptococcus, Neisseria, Veillonella, Gemella, and Porphyromonas), a protocol will also be presented describing how to harvest the biofilm cells for further subculture or DNA extraction and analysis. The limits of both the microfluidic biofilm system and the current state-of-the-art data analyses will be addressed. Ultimately, it is envisioned that this article will provide a baseline technique that will improve the study of oral biofilms and aid in the development of additional technologies that can be integrated with the microfluidic platform. PMID:25490193

  20. Compact electromagnetically operated microfluidic system for detection of sub-200-nm magnetic labels for biosensing without external pumps

    NASA Astrophysics Data System (ADS)

    Morimoto, Y.; Takamura, T.; Sandhu, A.

    2010-05-01

    The combination of small sample analyte volumes, high sensitivity, ease of use, high speed, and portability is an important factor for the development of protocols for point of care biodiagnosis. Currently, handling small amounts of liquids is achieved using microfluidic systems but it is challenging to satisfy the remaining factors using conventional approaches based on biosensors employing detection of fluorescent labels. Thus to resolve the other requirements, biosensing systems based on the detection of functionalized superparamagnetic beads acting as "magnetic labels" are being studied as an alternative approach. Notably, for greater quantification, there are increasing demands for the use of sub-200-nm magnetic labels, which are comparable in size to actual biomolecules. However, detection of small numbers of sub-200-nm diameter magnetic beads by magnetoresistive device-based platforms is extremely challenging due to the intrinsic noise of the electronic devices. In order to overcome the limitation, we have developed a simple procedure for detecting sub-200-nm diameter magnetic labels for biosensing via magnetically induced self-assembly of superparamagnetic beads. Applying our approach to conventional microfluidic systems satisfies the most of prerequisites; however conventional microfluidic systems attached to the external pumps are yet suitable for point of care biodiagnosis. Here we propose the development of an alternative biosensing system based on our previous work that does not require external pumps to achieve miniaturization.

  1. CO(2)-laser micromachining and back-end processing for rapid production of PMMA-based microfluidic systems.

    PubMed

    Klank, Henning; Kutter, Jorg P; Geschke, Oliver

    2002-11-01

    In this article, we focus on the enormous potential of a CO(2)-laser system for rapidly producing polymer microfluidic structures. The dependence was assessed of the depth and width of laser-cut channels on the laser beam power and on the number of passes of the beam along the same channel. In the experiments the laser beam power was varied between 0 and 40 W and the passes were varied in the range of 1 to 7 times. Typical channel depths were between 100 and 300 microm, while the channels were typically 250 microm wide. The narrowest produced channel was 85 microm wide. Several bonding methods for microstructured PMMA [poly(methyl methacrylate)] parts were investigated, such as solvent-assisted glueing, melting, laminating and surface activation using a plasma asher. A solvent-assisted thermal bonding method proved to be the most time-efficient one. Using laser micromachining together with bonding, a three-layer polymer microstructure with included optical fibers was fabricated within two days. The use of CO(2)-laser systems to produce microfluidic systems has not been published before. These systems provide a cost effective alternative to UV-laser systems and they are especially useful in microfluidic prototyping due to the very short cycle time of production.

  2. 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.

  3. 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.

  4. 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

  5. Imaging new transient nanostructures using a microfluidic chip integrated with a controlled environment vitrification system for cryogenic transmission electron microscopy.

    PubMed

    Lee, Jinkee; Jha, Ashish K; Bose, Arijit; Tripathi, Anubhav

    2008-11-18

    Nanostructures (vesicles, micelles, bilayers) are important in nanomedicine and biochemical processes. They are agents for encapsulation and eventual release of drugs, flavors, and fragrances. The structural transition from micelles to vesicles through disk-like intermediate states has been demonstrated previously. Here, we disclose a new route for the micelle-vesicle transition, where micelles aggregate to first form long tubules that become unstable, and break up into vesicles. A simple theory, based on energy principles, is presented to explain the tubule-vesicle transition. Observation of this new tubular intermediate state has been facilitated by the development of an integrated microfluidic chip/cryogenic transmission electron microscopy (cryo-TEM) unit. Although this transition has been observed in a specific amphiphilic system where micellar solutions of cetyltrimethylammonium bromide (CTAB) and dodecylbenzene sulfonic acid (HDBS) are mixed to form vesicles, this new tool can be applied broadly to study transient structures in nanoscale systems under the very controlled conditions provided by microfluidics.

  6. The development of mini pentameric STR loci for rapid analysis of forensic DNA samples on a microfluidic system.

    PubMed

    Aboud, Maurice J; Gassmann, Marcus; McCord, Bruce R

    2010-08-01

    There is increasing interest in developing methods for portable DNA analysis in mass disasters and criminal identification. Currently most forensic STR DNA analysis is performed by CE; however, these instruments are not portable and require long sample run times. One potential solution is the development of microfluidic systems for DNA typing. Unfortunately, fairly long (ca. 20 cm) separation channels are usually required for the proper resolution of multiplexed STR loci used in human identification. Commercially available systems like the Agilent 2100 Bioanalyzer have a small footprint and utilize chips with shorter channels and reduced resolution. Such portable systems might be valuable for evidence screening in remote locations. However, due to their lower resolution, most standard 4 base STR loci and their inherent 2 base variants will not resolve on such systems. In this paper, we discuss the development of reduced length pentameric (5 base) STR amplicons. Pentameric STRs have fewer variant alleles and are easier to separate due to the wider spacing between alleles. By incorporating novel denaturing sieving polymers in a short microfluidic channel, we demonstrate efficient separations on these chips. Such an approach can serve as a useful tool for rapid microfluidic DNA typing.

  7. A programmable and configurable multi-port System-on-Chip for stimulating electrokinetically-driven microfluidic devices.

    PubMed

    Lopez, Martha Salome; Gerstlauer, Andreas; Avila, Alfonso; Martinez-Chapa, Sergio O

    2011-01-01

    Recent research has demonstrated the use of microfluidic devices and electro-kinetics in areas such as medicine, genetics, embryology, epidemiology and pollution analysis, where manipulation of particles suspended in liquid media is required. Micro-fabrication technology has made it possible to increase system complexity and functionality by allowing integration of different processing and analysis stages in a single chip. However, fully integrated and autonomous microfluidic systems supporting ad-hoc stimulation have yet to be developed. This paper presents a flexible, configurable and programmable stimulator for electro-kinetically driven microfluidic devices. The stimulator is a dedicated System-on-Chip (SoC) architecture that generates sine, triangle, and sawtooth signals within a frequency range of 1 Hz to 20 MHz, capable of delivering single, dual, and superimposed waveforms, in a user defined test sequence for a selected time period. The system is designed to be integrated into complete, autonomous Lab-on-Chip, portable or implantable devices. As such, it is expected to help significantly advance current and future research on particle manipulation.

  8. 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

  9. An integrated microfluidic chip system for single-cell secretion profiling of rare circulating tumor cells.

    PubMed

    Deng, Yuliang; Zhang, Yu; Sun, Shuai; Wang, Zhihua; Wang, Minjiao; Yu, Beiqin; Czajkowsky, Daniel M; Liu, Bingya; Li, Yan; Wei, Wei; Shi, Qihui

    2014-12-16

    Genetic and transcriptional profiling, as well as surface marker identification of single circulating tumor cells (CTCs) have been demonstrated. However, quantitatively profiling of functional proteins at single CTC resolution has not yet been achieved, owing to the limited purity of the isolated CTC populations and a lack of single-cell proteomic approaches to handle and analyze rare CTCs. Here, we develop an integrated microfluidic system specifically designed for streamlining isolation, purification and single-cell secretomic profiling of CTCs from whole blood. Key to this platform is the use of photocleavable ssDNA-encoded antibody conjugates to enable a highly purified CTC population with <75 'contaminated' blood cells. An enhanced poly-L-lysine barcode pattern is created on the single-cell barcode chip for efficient capture rare CTC cells in microchambers for subsequent secreted protein profiling. This system was extensively evaluated and optimized with EpCAM-positive HCT116 cells seeded into whole blood. Patient blood samples were employed to assess the utility of the system for isolation, purification and single-cell secretion profiling of CTCs. The CTCs present in patient blood samples exhibit highly heterogeneous secretion profile of IL-8 and VEGF. The numbers of secreting CTCs are found not in accordance with CTC enumeration based on immunostaining in the parallel experiments.

  10. Laser Induced Dual Fluorescence Ratiometric Technique for Mixing Characterization in Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Bedding, David; Hidrovo, Carlso

    2016-11-01

    Increasing the rate of mixing within microfluidic systems is vitally important in understanding biological and chemical reaction kinetics and mechanisms. The small length scales characteristic of these systems which translate into highly viscous, Stokes flows result in mixing that is primarily dominated by diffusion. In order to counteract this, an approach that utilizes inertial droplet collisions to promote chaotic advection between two mixing species has been developed. A Laser-Induced Dual Fluorescence (LIDF) system in conjunction with a high-speed camera and appropriate optics are used to capture two intensity fields providing information about the mixing process as well as the excitation intensity field over the volume of interest. The rate of mixing for the coalescing droplets was quantified by taking the standard deviation of the first intensity field over time, while the second intensity field provides information about the intensity field. A ratiometric imaging approach allows removal of mixing fluorescence signal noise in the form of variation in excitation intensity, primarily from the lasing patterns and lensing effects within the interrogation volume. NSF CAREER Award Grant CBET - 1151091.

  11. Raman tweezers in microfluidic systems for analysis and sorting of living cells

    NASA Astrophysics Data System (ADS)

    Pilát, Zdenëk; Ježek, Jan; Kaňka, Jan; Zemánek, Pavel

    2014-03-01

    We have devised an analytical and sorting system combining optical trapping with Raman spectroscopy in microfluidic environment in order to identify and sort biological objects, such as living cells of various prokaryotic and eukaryotic organisms. Our main objective was to create a robust and universal platform for non-contact sorting of microobjects based on their Raman spectral properties. This approach allowed us to collect information about the chemical composition of the objects, such as the presence and composition of lipids, proteins, or nucleic acids without using artificial chemical probes such as fluorescent markers. The non-destructive and non-contact nature of this optical analysis and manipulation allowed us to separate individual living cells of our interest in a sterile environment and provided the possibility to cultivate the selected cells for further experiments. We used differently treated cells of algae to test and demonstrate the function of our analytical and sorting system. The devised system could find its use in many medical, biotechnological, and biological applications.

  12. A microfluidic cell culture system for monitoring of sequential changes in endothelial cells after heat stress.

    PubMed

    Tazawa, Hidekatsu; Sato, Kenjiro; Tsutiya, Atsuhiro; Tokeshi, Manabu; Ohtani-Kaneko, Ritsuko

    2015-08-01

    Endothelial damage induced by a highly elevated body temperature is crucial in some diseases including viral hemorrhagic fevers. Here, we report the heat-induced sequential changes of endothelial cells under shear stress, which were determined with a microfluidic culture system. Although live cell imaging showed only minor changes in the appearance of heat-treated cells, Hsp70 mRNA expression analysis demonstrated that the endothelial cells in channels of the system responded well to heat treatment. F-actin staining also revealed clear changes in the bundles of actin filaments after heat treatment. Well-organized bundles of actin filaments in control cells disappeared in heat-treated cells cultured in the channel. Furthermore, the system enabled detection of sequential changes in plasminogen activator inhibitor-1 (PAI-1) secretion from endothelial cells. PAI-1 concentration in the effluent solution was significantly elevated for the first 15min after initiation of heat treatment, and then decreased subsequently. This study provides fundamental information on heat-induced endothelial changes under shear stress and introduces a potent tool for analyzing endothelial secretions.

  13. Fertilization of Mouse Gametes in Vitro Using a Digital Microfluidic System.

    PubMed

    Huang, Hong-Yuan; Shen, Hsien-Hua; Chung, Lung-Yuan; Chung, Yu-Hsiang; Chen, Chih-Chen; Hsu, Chia-Hsien; Fan, Shih-Kang; Yao, Da-Jeng

    2015-12-01

    We demonstrated in vitro fertilization (IVF) using a digital microfluidic (DMF) system, so-called electrowetting on dielectric (EWOD). The DMF device was proved to be biocompatible and the DMF manipulation of a droplet was harmless to the embryos. This DMF platform was then used for the fertilization of mouse gametes in vitro and for embryo dynamic culture based on a dispersed droplet form. Development of the embryos was instantaneously recorded by a time-lapse microscope in an incubator. Our results indicated that increasing the number of sperms for IVF would raise the rate of fertilization. However, the excess of sperms in the 10 μL culture medium would more easily make the embryo dead during cell culture. Dynamic culture powered with EWOD can manipulate a single droplet containing mouse embryos and culture to the eight-cell stage. The fertilization rate of IVF demonstrated by DMF system was 34.8%, and about 25% inseminated embryos dynamically cultured on a DMF chip developed into an eight-cell stage. The results indicate that the DMF system has the potential for application in assisted reproductive technology.

  14. Probing Functional Properties of Nociceptive Axons Using a Microfluidic Culture System

    PubMed Central

    Tsantoulas, Christoforos; Farmer, Clare; Machado, Patricia; Baba, Katsuhiro; McMahon, Stephen B.; Raouf, Ramin

    2013-01-01

    Pathological changes in axonal function are integral features of many neurological disorders, yet our knowledge of the molecular basis of axonal dysfunction remains limited. Microfluidic chambers (MFCs) can provide unique insight into the axonal compartment independent of the soma. Here we demonstrate how an MFC based cell culture system can be readily adapted for the study of axonal function in vitro. We illustrate the ease and versatility to assay electrogenesis and conduction of action potentials (APs) in naïve, damaged or sensitized DRG axons using calcium imaging at the soma for pharmacological screening or patch-clamp electrophysiology for detailed biophysical characterisation. To demonstrate the adaptability of the system, we report by way of example functional changes in nociceptor axons following sensitization by neurotrophins and axotomy in vitro. We show that NGF can locally sensitize axonal responses to capsaicin, independent of the soma. Axotomizing neurons in MFC results in a significant increase in the proportion of neurons that respond to axonal stimulation, and interestingly leads to accumulation of Nav1.8 channels in regenerating axons. Axotomy also augmented AP amplitude following axotomy and altered activation thresholds in a subpopulation of regenerating axons. We further show how the system can readily be used to study modulation of axonal function by non-neuronal cells such as keratinocytes. Hence we describe a novel in vitro platform for the study of axonal function and a surrogate model for nerve injury and sensitization. PMID:24278311

  15. Raman tweezers in microfluidic systems for analysis and sorting of living cells

    NASA Astrophysics Data System (ADS)

    Pilát, Zdeněk.; Ježek, Jan; Kaňka, Jan; Zemánek, Pavel

    2014-12-01

    We have devised an analytical and sorting system combining optical trapping with Raman spectroscopy in microfluidic environment, dedicated to identification and sorting of biological objects, such as living cells of various unicellular organisms. Our main goal was to create a robust and universal platform for non-destructive and non-contact sorting of micro-objects based on their Raman spectral properties. This approach allowed us to collect spectra containing information about the chemical composition of the objects, such as the presence and composition of pigments, lipids, proteins, or nucleic acids, avoiding artificial chemical probes such as fluorescent markers. The non-destructive nature of this optical analysis and manipulation allowed us to separate individual living cells of our interest in a sterile environment and provided the possibility to cultivate the selected cells for further experiments. We used a mixture of polystyrene micro-particles and algal cells to test and demonstrate the function of our analytical and sorting system. The devised system could find its use in many medical, biotechnological, and biological applications.

  16. Integrated optical systems for excitation delivery and broadband detection in micro-fluidic electrochromatography

    SciTech Connect

    KEMME,SHANALYN A.; WARREN,MIAL E.; SWEATT,WILLIAM C.; WENDT,JOEL R.; BAILEY,CHRISTOPHER G.; MATZKE,CAROLYN M.; ALLERMAN,ANDREW A.; ARNOLD,DON W.; CARTER,TONY RAY; ASBILL,RANDOLPH E.; SAMORA,SALLY

    2000-03-15

    The authors have designed and assembled two generations of integrated micro-optical systems that deliver pump light and detect broadband laser-induced fluorescence in micro-fluidic chemical separation systems employing electrochromatography. The goal is to maintain the sensitivity attainable with larger, tabletop machines while decreasing package size and increasing throughput (by decreasing the required chemical volume). One type of micro-optical system uses vertical-cavity surface-emitting lasers (VCSELs) as the excitation source. Light from the VCSELs is relayed with four-level surface relief diffractive optical elements (DOEs) and delivered to the chemical volume through substrate-mode propagation. Indirect fluorescence from dye-quenched chemical species is collected and collimated with a high numerical aperture DOE. A filter blocks the excitation wavelength, and the resulting signal is detected as the chemical separation proceeds. Variations of this original design include changing the combination of reflective and transmissive DOEs and optimizing the high numerical aperture DOE with a rotationally symmetric iterative discrete on-axis algorithm. The authors will discuss the results of these implemented optimizations.

  17. All inkjet-printed electroactive polymer actuators for microfluidic lab-on-chip systems

    NASA Astrophysics Data System (ADS)

    Pabst, Oliver; Beckert, Erik; Perelaer, Jolke; Schubert, Ulrich S.; Eberhardt, Ramona; Tünnermann, Andreas

    2013-04-01

    Piezoelectric electroactive polymers (EAP) are promising materials for applications in microfluidic lab-on-chip systems. In such systems, fluids can be analyzed by different chemical or physical methods. During the analysis the fluids need to be distributed through the channels of the chip, which requires a pumping function. We present here all inkjet-printed EAP actuators that can be configured as a membrane-based micropump suitable for direct integration into lab-on-chip systems. Drop-on-demand inkjet printing is a versatile digital deposition technique that is capable of depositing various functional materials onto a wide variety of substrates in an additive way. Compared to conventional lithography-based processing it is cost-efficient and flexible, as no masking is required. The actuators consist of a polymer foil substrate with an inkjet-printed EAP layer sandwiched between a set of two electrodes. The actuators are printed using a commercially available EAP solution and silver nanoparticle inks. When a voltage is applied across the polymer layer, piezoelectric strain leads to a bending deflection of the beam or membrane. Circular membrane actuators with 20 mm diameter and EAP thicknesses of 10 to 15 μm exhibit deflections of several μm when driven at their resonance frequency with voltages of 110 V. From the behavior of membrane actuators a pumping rate of several 100 μL/min can be estimated, which is promising for applications in lab-on-chip devices.

  18. A microfluidic device and automatic counting system for the study of C. elegans reproductive aging

    PubMe