Metallization and Biopatterning on Ultra-Flexible Substrates via Dextran Sacrificial Layers

Science.gov (United States)

Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

2014-01-01

Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials. PMID:25153326

Shadowgraphy investigation of laser-induced forward transfer: Front side and back side ablation of the triazene polymer sacrificial layer

International Nuclear Information System (INIS)

Fardel, Romain; Nagel, Matthias; Nueesch, Frank; Lippert, Thomas; Wokaun, Alexander

2009-01-01

Thin films of a photodecomposible triazene polymer are used as sacrificial layer for the micro-deposition of sensitive materials by laser-induced forward transfer. To understand the ablation process of this sacrificial layer, the ultraviolet laser ablation of triazene films was investigated by time-resolved shadowgraphy. Irradiation from the film side shows a complete decomposition into gaseous fragments, while ablation through the substrate causes ejection of a solid flyer of polymer. The occurence of the flyer depends on the film thickness as well as on the applied fluence, and a compact flyer is obtaind when these two parameters are optimized

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

International Nuclear Information System (INIS)

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

2017-01-01

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. (paper)

Scalable Fabrication Framework of Implantable Ultrathin and Flexible Probes with Biodegradable Sacrificial Layers.

Science.gov (United States)

Jiao, Xiangbing; Wang, Yuan; Qing, Quan

2017-12-13

For long-term biocompatibility and performance, implanted probes need to further reduce their size and mechanical stiffness to match that of the surrounding cells, which, however, makes accurate and minimally invasive insertion operations difficult due to lack of rigidity and brings additional complications in assembling and surgery. Here, we report a scalable fabrication framework of implantable probes utilizing biodegradable sacrificial layers to address this challenge. Briefly, the integrated biodegradable sacrificial layer can dissolve in physiological fluids shortly after implantation, which allows the in situ formation of functional ultrathin film structures off of the initial small and rigid supporting backbone. We show that the dissolution of this layer does not affect the viability and excitability of neuron cells in vitro. We have demonstrated two types of probes that can be used out of the box, including (1) a compact probe that spontaneously forms three-dimensional bend-up devices only after implantation and (2) an ultraflexible probe as thin as 2 μm attached to a small silicon shaft that can be accurately delivered into the tissue and then get fully released in situ without altering its shape and position because the support is fully retracted. We have obtained a >93% yield of the bend-up structure, and its geometry and stiffness can be systematically tuned. The robustness of the ultraflexible probe has been tested in tissue-mimicking agarose gels with <1% fluctuation in the test resistance. Our work provides a general strategy to prepare ultrasmall and flexible implantable probes that allow high insertion accuracy and minimal surgical damages with the best biocompatibility.

Fabrication of relaxer-based piezoelectric energy harvesters using a sacrificial poly-Si seeding layer

KAUST Repository

Fuentes-Fernandez, E. M A

2014-08-07

The effect of a polycrystalline silicon (poly-Si) seeding layer on the properties of relaxor Pb(Zr0.53,Ti0.47)O3-Pb(Zn1/3,Nb2/3)O3 (PZT-PZN) thin films and energy-harvesting cantilevers was studied. We deposited thin films of the relaxor on two substrates, with and without a poly-Si seeding layer. The seeding layer, which also served as a sacrificial layer to facilitate cantilever release, was found to improve morphology, phase purity, crystal orientation, and electrical properties. We attributed these results to reduction of the number of nucleation sites and, therefore, to an increase in relaxor film grain size. The areal power density of the wet-based released harvester was measured. The power density output of the energy harvester with this relaxor composition and the poly-Si seeding layer was 325 μW/cm2.

Fabrication of relaxer-based piezoelectric energy harvesters using a sacrificial poly-Si seeding layer

KAUST Repository

Fuentes-Fernandez, E. M A; Salomon-Preciado, A. M.; Gnade, Bruce E.; Quevedo-Ló pez, Manuel Angel Quevedo; Shah, Pradeep; Alshareef, Husam N.

2014-01-01

The effect of a polycrystalline silicon (poly-Si) seeding layer on the properties of relaxor Pb(Zr0.53,Ti0.47)O3-Pb(Zn1/3,Nb2/3)O3 (PZT-PZN) thin films and energy-harvesting cantilevers was studied. We deposited thin films of the relaxor on two substrates, with and without a poly-Si seeding layer. The seeding layer, which also served as a sacrificial layer to facilitate cantilever release, was found to improve morphology, phase purity, crystal orientation, and electrical properties. We attributed these results to reduction of the number of nucleation sites and, therefore, to an increase in relaxor film grain size. The areal power density of the wet-based released harvester was measured. The power density output of the energy harvester with this relaxor composition and the poly-Si seeding layer was 325 μW/cm2.

Sacrificial-layer free transfer of mammalian cells using near infrared femtosecond laser pulses

Science.gov (United States)

Zhang, Jun; Hartmann, Bastian; Siegel, Julian; Marchi, Gabriele; Clausen-Schaumann, Hauke; Sudhop, Stefanie; Huber, Heinz P.

2018-01-01

Laser-induced cell transfer has been developed in recent years for the flexible and gentle printing of cells. Because of the high transfer rates and the superior cell survival rates, this technique has great potential for tissue engineering applications. However, the fact that material from an inorganic sacrificial layer, which is required for laser energy absorption, is usually transferred to the printed target structure, constitutes a major drawback of laser based cell printing. Therefore alternative approaches using deep UV laser sources and protein based acceptor films for energy absorption, have been introduced. Nevertheless, deep UV radiation can introduce DNA double strand breaks, thereby imposing the risk of carcinogenesis. Here we present a method for the laser-induced transfer of hydrogels and mammalian cells, which neither requires any sacrificial material for energy absorption, nor the use of UV lasers. Instead, we focus a near infrared femtosecond (fs) laser pulse (λ = 1030 nm, 450 fs) directly underneath a thin cell layer, suspended on top of a hydrogel reservoir, to induce a rapidly expanding cavitation bubble in the gel, which generates a jet of material, transferring cells and hydrogel from the gel/cell reservoir to an acceptor stage. By controlling laser pulse energy, well-defined cell-laden droplets can be transferred with high spatial resolution. The transferred human (SCP1) and murine (B16F1) cells show high survival rates, and good cell viability. Time laps microscopy reveals unaffected cell behavior including normal cell proliferation. PMID:29718923

Transfer of preheat-treated SnO 2 via a sacrificial bridge-type ZnO layer for ethanol gas sensor

KAUST Repository

Lee, Da Hoon

2017-08-05

The progress in developing the microelectromechanical system (MEMS) heater-based SnO2 gas sensors was hindered by the subsequent heat treatment of the tin oxide (SnO2), nevertheless it is required to obtain excellent sensor characteristics. During the sintering process, the MEMS heater and the contact electrodes can be degraded at such a high temperature, which could reduce the sensor response and reliability. In this research, we presented a process of preheating the printed SnO2 sensing layer on top of a sacrificial bridge-type ZnO layer at such a high temperature, followed by transferring it onto the contact electrodes of sensor device by selective etching of the sacrificial ZnO layer. Therefore, the sensor device was not exposed to the high sintering temperature. The SnO2 gas sensor fabricated by the transfer process exhibited a rectangular sensing curve behavior with a rapid response of 52 s at 20 ppm ethanol concentration. In addition, reliable and repeatable sensing characteristics were obtained even at an ethanol gas concentration of 5 ppm.

Transfer of preheat-treated SnO 2 via a sacrificial bridge-type ZnO layer for ethanol gas sensor

KAUST Repository

Lee, Da Hoon; Kang, Sun Kil; Pak, Yusin; Lim, Namsoo; Lee, Ryeri; Kumaresan, Yogeenth; Lee, Sungeun; Lee, Chaedeok; Ham, Moon-Ho; Jung, Gun Young

2017-01-01

The progress in developing the microelectromechanical system (MEMS) heater-based SnO2 gas sensors was hindered by the subsequent heat treatment of the tin oxide (SnO2), nevertheless it is required to obtain excellent sensor characteristics. During the sintering process, the MEMS heater and the contact electrodes can be degraded at such a high temperature, which could reduce the sensor response and reliability. In this research, we presented a process of preheating the printed SnO2 sensing layer on top of a sacrificial bridge-type ZnO layer at such a high temperature, followed by transferring it onto the contact electrodes of sensor device by selective etching of the sacrificial ZnO layer. Therefore, the sensor device was not exposed to the high sintering temperature. The SnO2 gas sensor fabricated by the transfer process exhibited a rectangular sensing curve behavior with a rapid response of 52 s at 20 ppm ethanol concentration. In addition, reliable and repeatable sensing characteristics were obtained even at an ethanol gas concentration of 5 ppm.

Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications

Science.gov (United States)

Wei, Yang; Torah, Russel; Yang, Kai; Beeby, Steve; Tudor, John

2013-07-01

Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications.

Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication

Energy Technology Data Exchange (ETDEWEB)

Rapp, Ludovic, E-mail: rapp@lp3.univ-mrs.fr [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Cibert, Christophe [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Nenon, Sebastien [CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) - UPR 3118 CNRS - Universite Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09 (France); Alloncle, Anne Patricia [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Nagel, Matthias [Empa, Swiss Federal Laboratories for Materials Testing and Reasearch, Laboratory for Functional Polymers, Uberlandstrasse 129, 8600 Duebendorf (Switzerland); Lippert, Thomas [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland); Videlot-Ackermann, Christine; Fages, Frederic [CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) - UPR 3118 CNRS - Universite Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09 (France); Delaporte, Philippe [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France)

2011-04-01

Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 {mu}s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

A microfluidic galvanic cell on a single layer of paper

Science.gov (United States)

Purohit, Krutarth H.; Emrani, Saina; Rodriguez, Sandra; Liaw, Shi-Shen; Pham, Linda; Galvan, Vicente; Domalaon, Kryls; Gomez, Frank A.; Haan, John L.

2016-06-01

Paper microfluidics is used to produce single layer galvanic and hybrid cells to produce energy that could power paper-based analytical sensors. When two aqueous streams are absorbed onto paper to establish co-laminar flow, the streams stay in contact with each other with limited mixing. The interface at which mixing occurs acts as a charge-transfer region, eliminating the need for a salt bridge. We designed a Cusbnd Zn galvanic cell that powers an LED when two are placed in series. We also used more powerful redox couples (formate and silver, formate and permanganate) to produce higher power density (18 and 3.1 mW mg-1 Pd). These power densities are greater than previously reported paper microfluidic fuel cells using formate or methanol. The single layer design is much more simplified than previous reports of multi-layer galvanic cells on paper.

Evaluation of sacrificial materials against spherical fragments in a semi-confined blast chamber

CSIR Research Space (South Africa)

Jiba, Z

2016-09-01

Full Text Available observed on the backing steel plates located behind the sacrificial layers exposed to 2 mm Chromium steel balls in a semi-confined environment. Conveyor belt, Polyurea / 1.6 mm mild steel material, Shutter board and Supawood were evaluated as sacrificial...

Fabrication of Covalently Crosslinked and Amine-Reactive Microcapsules by Reactive Layer-by-Layer Assembly of Azlactone-Containing Polymer Multilayers on Sacrificial Microparticle Templates

Science.gov (United States)

Saurer, Eric M.; Flessner, Ryan M.; Buck, Maren E.; Lynn, David M.

2011-01-01

We report on the fabrication of covalently crosslinked and amine-reactive hollow microcapsules using ‘reactive’ layer-by-layer assembly to deposit thin polymer films on sacrificial microparticle templates. Our approach is based on the alternating deposition of layers of a synthetic polyamine and a polymer containing reactive azlactone functionality. Multilayered films composed of branched poly(ethylene imine) (BPEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) were fabricated layer-by-layer on the surfaces of calcium carbonate and glass microparticle templates. After fabrication, these films contained residual azlactone functionality that was accessible for reaction with amine-containing molecules. Dissolution of the calcium carbonate or glass cores using aqueous ethylenediamine tetraacetic acid (EDTA) or hydrofluoric acid (HF), respectively, led to the formation of hollow polymer microcapsules. These microcapsules were robust enough to encapsulate and retain a model macromolecule (FITC-dextran) and were stable for at least 22 hours in high ionic strength environments, in low and high pH solutions, and in several common organic solvents. Significant differences in the behaviors of capsules fabricated on CaCO3 and glass cores were observed and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Whereas capsules fabricated on CaCO3 templates collapsed upon drying, capsules fabricated on glass templates remained rigid and spherical. Characterization using EDS suggested that this latter behavior results, at least in part, from the presence of insoluble metal fluoride salts that are trapped or precipitate within the walls of capsules after etching of the glass cores using HF. Our results demonstrate that the assembly of BPEI/PVDMA films on sacrificial templates can be used to fabricate reactive microcapsules of potential use in a wide range of fields, including catalysis, drug and gene delivery, imaging, and

Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications

International Nuclear Information System (INIS)

Wei, Yang; Torah, Russel; Yang, Kai; Beeby, Steve; Tudor, John

2013-01-01

Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications. (paper)

Fabrication of a microfluidic chip by UV bonding at room temperature for integration of temperature-sensitive layers

Science.gov (United States)

Schlautmann, S.; Besselink, G. A. J.; Radhakrishna Prabhu, G.; Schasfoort, R. B. M.

2003-07-01

A method for the bonding of a microfluidic device at room temperature is presented. The wafer with the fluidic structures was bonded to a sensor wafer with gold pads by means of adhesive bonding, utilizing an UV-curable glue layer. To avoid filling the fluidic channels with the glue, a stamping process was developed which allows the selective application of a thin glue layer. In this way a microfluidic glass chip was fabricated that could be used for performing surface plasmon resonance measurements without signs of leakage. The advantage of this method is the possibility of integration of organic layers as well as other temperature-sensitive layers into a microfluidic glass device.

Fabrication of 3D SiO x structures using patterned PMMA sacrificial layer

Science.gov (United States)

Li, Zhiqin; Xiang, Quan; Zheng, Mengjie; Bi, Kaixi; Chen, Yiqin; Chen, Keqiu; Duan, Huigao

2018-02-01

Three-dimensional (3D) nanofabrication based on electron-beam lithography (EBL) has drawn wide attention for various applications with its high patterning resolution and design flexibility. In this work, we present a bilayer EBL process to obtain 3D freestanding SiO x structures via the release of the bottom sacrificial layer. This new kind of bilayer process enables us to define various 3D freestanding SiO x structures with high resolution and low edge roughness. As a proof of concept for applications, metal-coated freestanding SiO x microplates with an underlying air gap were fabricated to form asymmetric Fabry-Perot resonators, which can be utilized for colorimetric refractive index sensing and thus also have application potential for biochemical detection, anti-counterfeiting and smart active nano-optical devices.

KAPOOL experiments to simulate molten corium - sacrificial concrete interaction

International Nuclear Information System (INIS)

Eppinger, B.; Fieg, G.; Tromm, W.

2001-01-01

In future Light Water Reactors special devices (core catchers) might be required to prevent containment failure by basement erosion after reactor pressure vessel melt-through during a core meltdown accident. In the planned European Pressurized Reactor (EPR) the core melt is retained in the reactor cavity for ∼ 1 h to pick up late melts after the failure of the reactor pressure vessel. The reactor cavity is protected by a layer of sacrificial concrete and closed by a melt gate at the bottom towards the spreading compartment. After erosion of the sacrificial concrete and melt-through of the gate the core melt should be distributed homogeneously into the spreading compartment. There the melt is cooled by flooding with water. The knowledge of the sacrificial concrete erosion phase in the reactor cavity is essential for the severe accident assessment. Several KAPOOL experiments have been performed to investigate the erosion of two possible compositions of sacrificial concretes using alumina-iron thermite melts as a simulant for the core melt. Erosion rates as a function of the melt temperature and the inhomogeneity of the melt front are presented in this paper. (authors)

Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

Directory of Open Access Journals (Sweden)

Costescu Ruxandra

2009-01-01

Full Text Available Abstract The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

Sacrificial wafer bonding for planarization after very deep etching

NARCIS (Netherlands)

Spiering, V.L.; Spiering, Vincent L.; Berenschot, Johan W.; Elwenspoek, Michael Curt; Fluitman, J.H.J.

A new technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for as well resist spinning and layer patterning as realization of bridges or cantilevers across deep holes or grooves. The sacrificial wafer bonding technique contains a

Porous double-layer polymer tubing for the potential use in heterogeneous continuous flow reactions.

Science.gov (United States)

Herwig, Gordon; Hornung, Christian H; Peeters, Gary; Ebdon, Nicholas; Savage, G Paul

2014-12-24

Functional polymer tubing with an OD of 1/16 or 1/8 in. was fabricated by a simple polymer coextrusion process. The tubing was made of an outer impervious polypropylene layer and an inner layer, consisting of a blend of a functional polymer, polyethylene-co-methacrylic acid, and a sacrificial polymer, polystyrene. After a simple solvent leaching step using common organic solvents, the polystyrene was removed, leaving behind a porous inner layer that contains functional carboxylic acid groups, which could then be used for the immobilization of target molecules. Solution-phase reactions using amines or isocyanates have proven successful for the immobilization of a series of small molecules and polymers. This flexible multilayered functional tubing can be easily cut to the desired length and connected via standard microfluidic fittings.

Low temperature sacrificial wafer bonding for planarization after very deep etching

NARCIS (Netherlands)

Spiering, V.L.; Spiering, V.L.; Berenschot, Johan W.; Elwenspoek, Michael Curt; Fluitman, J.H.J.

1994-01-01

A new technique, at temperatures of 150°C or 450°C, that provides planarization after a very deep etching step in silicon is presented. Resist spinning and layer patterning as well as realization of bridges or cantilevers across deep holes becomes possible. The sacrificial wafer bonding technique

Desktop aligner for fabrication of multilayer microfluidic devices.

Science.gov (United States)

Li, Xiang; Yu, Zeta Tak For; Geraldo, Dalton; Weng, Shinuo; Alve, Nitesh; Dun, Wu; Kini, Akshay; Patel, Karan; Shu, Roberto; Zhang, Feng; Li, Gang; Jin, Qinghui; Fu, Jianping

2015-07-01

Multilayer assembly is a commonly used technique to construct multilayer polydimethylsiloxane (PDMS)-based microfluidic devices with complex 3D architecture and connectivity for large-scale microfluidic integration. Accurate alignment of structure features on different PDMS layers before their permanent bonding is critical in determining the yield and quality of assembled multilayer microfluidic devices. Herein, we report a custom-built desktop aligner capable of both local and global alignments of PDMS layers covering a broad size range. Two digital microscopes were incorporated into the aligner design to allow accurate global alignment of PDMS structures up to 4 in. in diameter. Both local and global alignment accuracies of the desktop aligner were determined to be about 20 μm cm(-1). To demonstrate its utility for fabrication of integrated multilayer PDMS microfluidic devices, we applied the desktop aligner to achieve accurate alignment of different functional PDMS layers in multilayer microfluidics including an organs-on-chips device as well as a microfluidic device integrated with vertical passages connecting channels located in different PDMS layers. Owing to its convenient operation, high accuracy, low cost, light weight, and portability, the desktop aligner is useful for microfluidic researchers to achieve rapid and accurate alignment for generating multilayer PDMS microfluidic devices.

Electroless atomic layer deposition

Science.gov (United States)

Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

2017-10-31

A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.

A simple and cost-effective method for fabrication of integrated electronic-microfluidic devices using a laser-patterned PDMS layer

KAUST Repository

Li, Ming

2011-12-03

We report a simple and cost-effective method for fabricating integrated electronic-microfluidic devices with multilayer configurations. A CO 2 laser plotter was employed to directly write patterns on a transferred polydimethylsiloxane (PDMS) layer, which served as both a bonding and a working layer. The integration of electronics in microfluidic devices was achieved by an alignment bonding of top and bottom electrode-patterned substrates fabricated with conventional lithography, sputtering and lift-off techniques. Processes of the developed fabrication method were illustrated. Major issues associated with this method as PDMS surface treatment and characterization, thickness-control of the transferred PDMS layer, and laser parameters optimization were discussed, along with the examination and testing of bonding with two representative materials (glass and silicon). The capability of this method was further demonstrated by fabricating a microfluidic chip with sputter-coated electrodes on the top and bottom substrates. The device functioning as a microparticle focusing and trapping chip was experimentally verified. It is confirmed that the proposed method has many advantages, including simple and fast fabrication process, low cost, easy integration of electronics, strong bonding strength, chemical and biological compatibility, etc. © Springer-Verlag 2011.

Valve Concepts for Microfluidic Cell Handling

Directory of Open Access Journals (Sweden)

M. Grabowski

2010-01-01

Full Text Available In this paper we present various pneumatically actuated microfluidic valves to enable user-defined fluid management within a microfluidic chip. To identify a feasible valve design, certain valve concepts are simulated in ANSYS to investigate the pressure dependent opening and closing characteristics of each design. The results are verified in a series of tests. Both the microfluidic layer and the pneumatic layer are realized by means of soft-lithographic techniques. In this way, a network of channels is fabricated in photoresist as a molding master. By casting these masters with PDMS (polydimethylsiloxane we get polymeric replicas containing the channel network. After a plasma-enhanced bonding process, the two layers are irreversibly bonded to each other. The bonding is tight for pressures up to 2 bar. The valves are integrated into a microfluidic cell handling system that is designed to manipulate cells in the presence of a liquid reagent (e.g. PEG – polyethylene glycol, for cell fusion. For this purpose a user-defined fluid management system is developed. The first test series with human cell lines show that the microfluidic chip is suitable for accumulating cells within a reaction chamber, where they can be flushed by a liquid medium.

A sacrificial process for fabrication of biodegradable polymer membranes with submicron thickness.

Science.gov (United States)

Beardslee, Luke A; Stolwijk, Judith; Khaladj, Dimitrius A; Trebak, Mohamed; Halman, Justin; Torrejon, Karen Y; Niamsiri, Nuttawee; Bergkvist, Magnus

2016-08-01

A new sacrificial molding process using a single mask has been developed to fabricate ultrathin 2-dimensional membranes from several biocompatible polymeric materials. The fabrication process is similar to a sacrificial microelectromechanical systems (MEMS) process flow, where a mold is created from a material that can be coated with a biodegradable polymer and subsequently etched away, leaving behind a very thin polymer membrane. In this work, two different sacrificial mold materials, silicon dioxide (SiO2 ) and Liftoff Resist (LOR) were used. Three different biodegradable materials; polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), and polyglycidyl methacrylate (PGMA), were chosen as model polymers. We demonstrate that this process is capable of fabricating 200-500 nm thin, through-hole polymer membranes with various geometries, pore-sizes and spatial features approaching 2.5 µm using a mold fabricated via a single contact photolithography exposure. In addition, the membranes can be mounted to support rings made from either SU8 or PCL for easy handling after release. Cell culture compatibility of the fabricated membranes was evaluated with human dermal microvascular endothelial cells (HDMECs) seeded onto the ultrathin porous membranes, where the cells grew and formed confluent layers with well-established cell-cell contacts. Furthermore, human trabecular meshwork cells (HTMCs) cultured on these scaffolds showed similar proliferation as on flat PCL substrates, further validating its compatibility. All together, these results demonstrated the feasibility of our sacrificial fabrication process to produce biocompatible, ultra-thin membranes with defined microstructures (i.e., pores) with the potential to be used as substrates for tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1192-1201, 2016. © 2015 Wiley Periodicals, Inc.

Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

Energy Technology Data Exchange (ETDEWEB)

Li, Gen; Liu, Ming, E-mail: ming.liu@mail.xjtu.edu.cn; Wang, Jinshi; Chong, Daotong; Yan, Junjie

2017-04-01

Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

Development of an SU-8 MEMS process with two metal electrodes using amorphous silicon as a sacrificial material

KAUST Repository

Ramadan, Khaled S.; Nasr, Tarek Adel Hosny; Foulds, Ian G.

2013-01-01

method using XeF2, which alleviates release-based stiction problems related to MEMS applications. In this work, an SU-8 MEMS process was developed using ;-Si as a sacrificial layer. Two conductive metal electrodes were integrated in this process to allow

A simple method for fabricating multi-layer PDMS structures for 3D microfluidic chips

KAUST Repository

Zhang, Mengying

2010-01-01

We report a simple methodology to fabricate PDMS multi-layer microfluidic chips. A PDMS slab was surface-treated by trichloro (1H,1H,2H,2H-perfluorooctyl) silane, and acts as a reusable transferring layer. Uniformity of the thickness of the patterned PDMS layer and the well-alignment could be achieved due to the transparency and proper flexibility of this transferring layer. Surface treatment results are confirmed by XPS and contact angle testing, while bonding forces between different layers were measured for better understanding of the transferring process. We have also designed and fabricated a few simple types of 3D PDMS chip, especially one consisting of 6 thin layers (each with thickness of 50 μm), to demonstrate the potential utilization of this technique. 3D fluorescence images were taken by a confocal microscope to illustrate the spatial characters of essential parts. This fabrication method is confirmed to be fast, simple, repeatable, low cost and possible to be mechanized for mass production. © The Royal Society of Chemistry 2010.

Development of an Integrated Polymer Microfluidic Stack

International Nuclear Information System (INIS)

Datta, Proyag; Hammacher, Jens; Pease, Mark; Gurung, Sitanshu; Goettert, Jost

2006-01-01

Microfluidic is a field of considerable interest. While significant research has been carried out to develop microfluidic components, very little has been done to integrate the components into a complete working system. We present a flexible modular system platform that addresses the requirements of a complete microfluidic system. A microfluidic stack system is demonstrated with the layers of the stack being modular for specific functions. The stack and accompanying infrastructure provides an attractive platform for users to transition their design concepts into a working microfluidic system quickly with very little effort. The concept is demonstrated by using the system to carry out a chemilumiscence experiment. Details regarding the fabrication, assembly and experimental methods are presented

Silica sacrificial layer-assisted in-plane incorporation of Au nanoparticles into mesoporous titania thin films through different reduction methods.

Science.gov (United States)

Liang, Chih-Peng; Yamauchi, Yusuke; Liu, Chia-Hung; Wu, Kevin C-W

2013-06-28

This study focuses on the incorporation of gold nanoparticles (Au NPs) into our previously synthesized mesoporous titania thin films consisting of titania nanopillars and inverse mesospace (C. W. Wu, T. Ohsuna, M. Kuwabara and K. Kuroda, J. Am. Chem. Soc., 2006, 128, 4544-4545, denoted as MTTFs). Recently, mesoporous titania materials doped with noble metals such as gold have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, photo irradiation, liquid immersion, and vapor contacting) to introduce gold nanoparticles (Au NPs) into MTTFs. The synthesized Au@MTTFs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We further systematically investigated the formation mechanism of gold nanoparticles on the external and internal surfaces of the MTTFs. With the assistance of a silica sacrificial layer, well-dispersed Au NPs with sizes of 4.1 nm were obtained inside the MTTF by photo irradiation. The synthesized Au@MTTF materials show great potential in various photo-electronic and photo-catalytic applications.

Measurement of in-plane elasticity of live cell layers using a pressure sensor embedded microfluidic device

Science.gov (United States)

Lin, Chien-Han; Wang, Chien-Kai; Chen, Yu-An; Peng, Chien-Chung; Liao, Wei-Hao; Tung, Yi-Chung

2016-11-01

In various physiological activities, cells experience stresses along their in-plane direction when facing substrate deformation. Capability of continuous monitoring elasticity of live cell layers during a period is highly desired to investigate cell property variation during various transformations under normal or disease states. This paper reports time-lapsed measurement of live cell layer in-plane elasticity using a pressure sensor embedded microfluidic device. The sensor converts pressure-induced deformation of a flexible membrane to electrical signals. When cells are cultured on top of the membrane, flexural rigidity of the composite membrane increases and further changes the output electrical signals. In the experiments, human embryonic lung fibroblast (MRC-5) cells are cultured and analyzed to estimate the in-plane elasticity. In addition, the cells are treated with a growth factor to simulate lung fibrosis to study the effects of cell transformation on the elasticity variation. For comparison, elasticity measurement on the cells by atomic force microscopy (AFM) is also performed. The experimental results confirm highly anisotropic configuration and material properties of cells. Furthermore, the in-plane elasticity can be monitored during the cell transformation after the growth factor stimulation. Consequently, the developed microfluidic device provides a powerful tool to study physical properties of cells for fundamental biophysics and biomedical researches.

Magnet-assisted device-level alignment for the fabrication of membrane-sandwiched polydimethylsiloxane microfluidic devices

International Nuclear Information System (INIS)

Lu, J-C; Liao, W-H; Tung, Y-C

2012-01-01

Polydimethylsiloxane (PDMS) microfluidic device is one of the most essential techniques that advance microfluidics research in recent decades. PDMS is broadly exploited to construct microfluidic devices due to its unique and advantageous material properties. To realize more functionalities, PDMS microfluidic devices with multi-layer architectures, especially those with sandwiched membranes, have been developed for various applications. However, existing alignment methods for device fabrication are mainly based on manual observations, which are time consuming, inaccurate and inconsistent. This paper develops a magnet-assisted alignment method to enhance device-level alignment accuracy and precision without complicated fabrication processes. In the developed alignment method, magnets are embedded into PDMS layers at the corners of the device. The paired magnets are arranged in symmetric positions at each PDMS layer, and the magnetic attraction force automatically pulls the PDMS layers into the aligned position during assembly. This paper also applies the method to construct a practical microfluidic device, a tunable chaotic micromixer. The results demonstrate the successful operation of the device without failure, which suggests the accurate alignment and reliable bonding achieved by the method. Consequently, the fabrication method developed in this paper is promising to be exploited to construct various membrane-sandwiched PDMS microfluidic devices with more integrated functionalities to advance microfluidics research. (paper)

Microfabrication of SrRuO3 thin films on various oxide substrates using LaAlO3/BaOx sacrificial bilayers

Science.gov (United States)

Harada, Takayuki; Tsukazaki, Atsushi

2018-02-01

Oxides provide various fascinating physical properties that could find use in future device applications. However, the physical properties of oxides are often affected by formation of oxygen vacancies during device fabrication processes. In this study, to develop a damage-free patterning process for oxides, we focus on a lift-off process using a sacrificial template layer, by which we can pattern oxide thin films without severe chemical treatment or plasma bombardment. As oxides need high thin-film growth temperature, a sacrificial template needs to be made of thermally stable and easily etchable materials. To meet these requirements, we develop a sacrificial template with a carefully designed bilayer structure. Combining a thermally and chemically stable LaAlO3 and a water-soluble BaOx, we fabricated a LaAlO3/BaOx sacrificial bilayer. The patterned LaAlO3/BaOx sacrificial bilayers were prepared on oxide substrates by room-temperature pulsed laser deposition and standard photolithography process. The structure of the sacrificial bilayer can be maintained even in rather tough conditions needed for oxide thin film growth: several hundred degrees Celsius under high oxygen pressure. Indeed, the LaAlO3/BaOx bilayer is easily removable by sonication in water. We applied the lift-off method using the LaAlO3/BaOx sacrificial bilayer to a representative oxide conductor SrRuO3 and fabricated micron-scale Hall-bar devices. The SrRuO3 channels with the narrowest line width of 5 μm exhibit an almost identical transport property to that of the pristine film, evidencing that the developed process is beneficial for patterning oxides. We show that the LaAlO3/BaOx lift-off process is applicable to various oxide substrates: SrTiO3, MgO, and Al2O3. The new versatile patterning process will expand the range of application of oxide thin films in electronic and photonic devices.

Surfactant-assisted sacrificial template-mediated synthesis

Indian Academy of Sciences (India)

... spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopyand photoluminescence studies. Influence of surfactant and solvents on morphology and luminescence of the final product in sacrificial template-assisted method has been investigated in detail.

A microfluidic device based on an evaporation-driven micropump

NARCIS (Netherlands)

Nie, C.; Frijns, A.J.H.; Mandamparambil, R.; Toonder, J.M.J. den

2015-01-01

In this paper we introduce a microfluidic device ultimately to be applied as a wearable sweat sensor. We show proof-of-principle of the microfluidic functions of the device, namely fluid collection and continuous fluid flow pumping. A filter-paper based layer, that eventually will form the interface

Biofabrication of Tobacco mosaic virus-nanoscaffolded supercapacitors via temporal capillary microfluidics

Science.gov (United States)

Zang, Faheng; Chu, Sangwook; Gerasopoulos, Konstantinos; Culver, James N.; Ghodssi, Reza

2017-06-01

This paper reports the implementation of temporal capillary microfluidic patterns and biological nanoscaffolds in autonomous microfabrication of nanostructured symmetric electrochemical supercapacitors. A photoresist layer was first patterned on the substrate, forming a capillary microfluidics layer with two separated interdigitated microchannels. Tobacco mosaic virus (TMV) macromolecules suspended in solution are autonomously delivered into the microfluidics, and form a dense bio-nanoscaffolds layer within an hour. This TMV layer is utilized in the electroless plating and thermal oxidation for creating nanostructured NiO supercapacitor. The galvanostatic charge/discharge cycle showed a 3.6-fold increase in areal capacitance for the nanostructured electrode compared to planar structures. The rapid creation of nanostructure-textured microdevices with only simple photolithography and bionanostructure self-assembly can completely eliminate the needs for sophisticated synthesis or deposition processes. This method will contribute to rapid prototyping of wide range of nano-/micro-devices with enhanced performance.

A new UV-curing elastomeric substrate for rapid prototyping of microfluidic devices

Science.gov (United States)

Alvankarian, Jafar; Yeop Majlis, Burhanuddin

2012-03-01

Rapid prototyping in the design cycle of new microfluidic devices is very important for shortening time-to-market. Researchers are facing the challenge to explore new and suitable substrates with simple and efficient microfabrication techniques. In this paper, we introduce and characterize a UV-curing elastomeric polyurethane methacrylate (PUMA) for rapid prototyping of microfluidic devices. The swelling and solubility of PUMA in different chemicals is determined. Time-dependent measurements of water contact angle show that the native PUMA is hydrophilic without surface treatment. The current monitoring method is used for measurement of the electroosmotic flow mobility in the microchannels made from PUMA. The optical, physical, thermal and mechanical properties of PUMA are evaluated. The UV-lithography and molding process is used for making micropillars and deep channel microfluidic structures integrated to the supporting base layer. Spin coating is characterized for producing different layer thicknesses of PUMA resin. A device is fabricated and tested for examining the strength of different bonding techniques such as conformal, corona treating and semi-curing of two PUMA layers in microfluidic application and the results show that the bonding strengths are comparable to that of PDMS. We also report fabrication and testing of a three-layer multi inlet/outlet microfluidic device including a very effective fluidic interconnect for application demonstration of PUMA as a promising new substrate. A simple micro-device is developed and employed for observing the pressure deflection of membrane made from PUMA as a very effective elastomeric valve in microfluidic devices.

Magnesium sacrificial anode behavior at elevated temperature

International Nuclear Information System (INIS)

Othman, Mohsen Othman

2006-01-01

Magnesium sacrificial anode coupled to mild steel was tasted in sodium chloride and tap water environments at elevated temperatures. The anode failed to protect the mild steel specimens in tap water environment at all temperatures specified. This was partly due to low conductivity of this medium. The temperature factor did not help to activate the anode in this medium. In sodium chloride environment the anode demonstrated good protection for steel cathodes. The weight loss was high for magnesium in sodium chloride environment particularly beyond 60 degree centigrade. In tap water environment the weight loss was negligible for the anode. It also suffered localized shallow pitting corrosion. Magnesium anode cannot be utilized where high temperature is involved particularly in high conductivity mediums. Protection of structures containing high resistivity waters is not feasible using sacrificial anode system. (author)

Non-Sacrificial, Anti-Graffiti Coating 2009 Evaluation

Science.gov (United States)

2010-04-01

Graffiti eradication is a problem for the Nevada Department of Transportation (NDOT). Over 12,000 man-hours are spent on graffiti eradication each year. One recognized graffiti abatement method is the use of non-sacrificial, anti-graffiti coating. ND...

When does self-sacrificial leadership motivate prosocial behavior? It depends on followers' prevention focus.

Science.gov (United States)

De Cremer, David; Mayer, David M; van Dijke, Marius; Bardes, Mary; Schouten, Barbara C

2009-07-01

In the present set of studies, the authors examine the idea that self-sacrificial leadership motivates follower prosocial behavior, particularly among followers with a prevention focus. Drawing on the self-sacrificial leadership literature and regulatory focus theory, the authors provide results from 4 studies (1 laboratory and 3 field studies) that support the research hypothesis. Specifically, the relationship between self-sacrificial leadership and prosocial behavior (i.e., cooperation, organizational citizenship behavior) is stronger among followers who are high in prevention focus. Implications for the importance of taking a follower-centered approach to leadership are discussed.

Reagent-loaded plastic microfluidic chips for detecting homocysteine

International Nuclear Information System (INIS)

Suk, Ji Won; Jang, Jae-Young; Cho, Jun-Hyeong

2008-01-01

This report describes the preliminary study on plastic microfluidic chips with pre-loaded reagents for detecting homocysteine (Hcy). All reagents needed in an Hcy immunoassay were included in a microfluidic chip to remove tedious assay steps. A simple and cost-effective bonding method was developed to realize reagent-loaded microfluidic chips. This technique uses an intermediate layer between two plastic substrates by selectively patterning polydimethylsiloxane (PDMS) on the embossed surface of microchannels and fixing the substrates under pressure. Using this bonding method, the competitive immunoassay for SAH, a converted form of Hcy, was performed without any damage to reagents in chips, and the results showed that the fluorescent signal from antibody antigen binding decreased as the SAH concentration increased. Based on the SAH immunoassay, whole immunoassay steps for Hcy detection were carried out in plastic microfluidic chips with all necessary reagents. These experiments demonstrated the feasibility of the Hcy immunoassay in microfluidic devices

Single step sequential polydimethylsiloxane wet etching to fabricate a microfluidic channel with various cross-sectional geometries

Science.gov (United States)

Wang, C.-K.; Liao, W.-H.; Wu, H.-M.; Lo, Y.-H.; Lin, T.-R.; Tung, Y.-C.

2017-11-01

Polydimethylsiloxane (PDMS) has become a widely used material to construct microfluidic devices for various biomedical and chemical applications due to its desirable material properties and manufacturability. PDMS microfluidic devices are usually fabricated using soft lithography replica molding methods with master molds made of photolithogrpahy patterned photoresist layers on silicon wafers. The fabricated microfluidic channels often have rectangular cross-sectional geometries with single or multiple heights. In this paper, we develop a single step sequential PDMS wet etching process that can be used to fabricate microfluidic channels with various cross-sectional geometries from single-layer PDMS microfluidic channels. The cross-sections of the fabricated channel can be non-rectangular, and varied along the flow direction. Furthermore, the fabricated cross-sectional geometries can be numerically simulated beforehand. In the experiments, we fabricate microfluidic channels with various cross-sectional geometries using the developed technique. In addition, we fabricate a microfluidic mixer with alternative mirrored cross-sectional geometries along the flow direction to demonstrate the practical usage of the developed technique.

When does self-sacrificial leadership motivate prosocial behavior? It depends on followers’ prevention focus

NARCIS (Netherlands)

de Cremer, D.; Mayer, D.M.; van Dijke, M.; Schouten, B.C.; Bardes, M.

2009-01-01

In the present set of studies, the authors examine the idea that self-sacrificial leadership motivates follower prosocial behavior, particularly among followers with a prevention focus. Drawing on the self-sacrificial leadership literature and regulatory focus theory, the authors provide results

Effect of Copper and Silicon on Al-5%Zn Alloy as a Candidate Low Voltage Sacrificial Anode

Science.gov (United States)

Pratesa, Yudha; Ferdian, Deni; Togina, Inez

2017-05-01

One common method used for corrosion protection is a sacrificial anode. Sacrificial anodes that usually employed in the marine environment are an aluminum alloy sacrificial anode, especially Al-Zn-In. However, the electronegativity of these alloys can cause corrosion overprotection and stress cracking (SCC) on a high-strength steel. Therefore, there is a development of the sacrificial anode aluminum low voltage to reduce the risk of overprotection. The addition of alloying elements such as Cu, Si, and Ge will minimize the possibility of overprotection. This study was conducted to analyze the effect of silicon and copper addition in Al-5Zn. The experiment started from casting the sacrificial anode aluminum uses electrical resistance furnace in a graphite crucible in 800°C. The results alloy was analyzed using Optical emission spectroscopy (OES), Differential scanning calorimetry, electrochemical impedance spectroscopy, and metallography. Aluminum alloy with the addition of a copper alloy is the most suitable and efficient to serve as a low-voltage sacrificial anode aluminum. Charge transfer resistivity of copper is smaller than silicon which indicates that the charge transfer between the metal and the electrolyte is easier t to occur. Also, the current potential values in coupling with steel are also in the criteria range of low-voltage aluminum sacrificial anodes.

Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals.

Science.gov (United States)

Gupta, Deeksha; Sarker, Bivas; Thadikaran, Keith; John, Vijay; Maldarelli, Charles; John, George

2015-06-01

Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as "chemical herder" is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air-sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice.

A microfluidic renal proximal tubule with active reabsorptive function.

Directory of Open Access Journals (Sweden)

Else M Vedula

Full Text Available In the kidney, the renal proximal tubule (PT reabsorbs solutes into the peritubular capillaries through active transport. Here, we replicate this reabsorptive function in vitro by engineering a microfluidic PT. The microfluidic PT architecture comprises a porous membrane with user-defined submicron surface topography separating two microchannels representing a PT filtrate lumen and a peritubular capillary lumen. Human PT epithelial cells and microvascular endothelial cells in respective microchannels created a PT-like reabsorptive barrier. Co-culturing epithelial and endothelial cells in the microfluidic architecture enhanced viability, metabolic activity, and compactness of the epithelial layer. The resulting tissue expressed tight junctions, kidney-specific morphology, and polarized expression of kidney markers. The microfluidic PT actively performed sodium-coupled glucose transport, which could be modulated by administration of a sodium-transport inhibiting drug. The microfluidic PT reproduces human physiology at the cellular and tissue levels, and measurable tissue function which can quantify kidney pharmaceutical efficacy and toxicity.

Can nature's design be improved upon? High strength, transparent nacre-like nanocomposites with double network of sacrificial cross links.

Science.gov (United States)

Podsiadlo, Paul; Kaushik, Amit K; Shim, Bong Sup; Agarwal, Ashish; Tang, Zhiyong; Waas, Anthony M; Arruda, Ellen M; Kotov, Nicholas A

2008-11-20

The preparation of a high-strength and highly transparent nacre-like nanocomposite via layer-by-layer assembly technique from poly(vinyl alcohol) (PVA) and Na+-montmorillonite clay nanosheets is reported in this article. We show that a high density of weak bonding interactions between the polymer and the clay particles: hydrogen, dipole-induced dipole, and van der Waals undergoing break-reform deformations, can lead to high strength nanocomposites: sigmaUTS approximately 150 MPa and E' approximately 13 GPa. Further introduction of ionic bonds into the polymeric matrix creates a double network of sacrificial bonds which dramatically increases the mechanical properties: sigmaUTS approximately 320 MPa and E' approximately 60 GPa.

New sacrificial material for ex-vessel core catcher

Energy Technology Data Exchange (ETDEWEB)

Komlev, Andrei A., E-mail: komlev@kth.se [Kungliga Tekniska Högskolan (KTH), AlbaNova University Centre, Nuclear Power Safety Division, Roslagstullsbacken 21, SE-106 91, Stockholm (Sweden); Almjashev, Vyacheslav I., E-mail: vac@mail.ru [A.P. Aleksandrov Research Institute of Technology, NITI, DSAR, Sosnovy Bor, 188540 (Russian Federation); Bechta, Sevostian V., E-mail: bechta@safety.sci.kth.se [Kungliga Tekniska Högskolan (KTH), AlbaNova University Centre, Roslagstullsbacken 21, SE-106 91, Stockholm (Sweden); Khabensky, Vladimir B., E-mail: vladimirkhabensky@gmail.com [A.P. Aleksandrov Research Institute of Technology, NITI, DSAR, Sosnovy Bor, 188540 (Russian Federation); Granovsky, Vladimir S., E-mail: gran@niti.ru [A.P. Aleksandrov Research Institute of Technology, NITI, DSAR, Sosnovy Bor, 188540 (Russian Federation); Gusarov, Victor V., E-mail: victor.v.gusarov@gmail.com [Ioffe Institute, 26 Polytekhnicheskaya Str., St. Petersburg, 194021 (Russian Federation)

2015-12-15

A new functional (sacrificial) material has been developed in the Fe{sub 2}O{sub 3}–SrO–Al{sub 2}O{sub 3}–CaO system based on strontium hexaferrite ceramic in concrete matrix. The method of producing SM has been advanced technologically; this technological effectiveness allows the SM to be used in ex-vessel core catchers with corium spreading as well as in crucible-type core catchers. Critical properties regarding the efficiency of SM in ex-vessel core catchers, such as porosity, pycnometric density, apparent density, solidus and liquidus temperatures, and water content have been measured. Suitable fractions of SrFe{sub 12}O{sub 19} and high alumina cement (HAC) were found in the SM based on thermodynamic analysis of the SM/corium interaction. The use of sacrificial steel as an additional heat adsorption component in the core catcher allowed us to increase the mass fraction range of SrFe{sub 12}O{sub 19} in the SM from 0.3−0.5 to 0.3–0.85. The activation temperature of the SM/corium interaction has been shown to correspond to the liquidus temperature of the local composition at the SM/corium interface. The calculated value of this temperature was 1716 °C. Analysis of phase transformations in the SrO–Fe{sub 2}O{sub 3} system revealed advantages of the SrFe{sub 12}O{sub 19}–based sacrificial material compared with the Fe{sub 2}O{sub 3}-contained material owing to the time proximity of SrFe{sub 12}O{sub 19} decomposition and corium interaction activation. - Highlights: • A sacrificial material (SM) was developed for ex-vessel core catcher. • Suitable proportions in the SrFe{sub 12}O{sub 19}–Al{sub 2}O{sub 3}·CaO–Fe system were determined. • Hydrogen release limitation was shown for ex-vessel corium retention with the SM. • Calculated temperature of the active initiation of corium/SM interaction is 1716 °C. • Functional properties of the SM were measured.

Metal-coated microfluidic channels: An approach to eliminate streaming potential effects in nano biosensors.

Science.gov (United States)

Lee, Jieun; Wipf, Mathias; Mu, Luye; Adams, Chris; Hannant, Jennifer; Reed, Mark A

2017-01-15

We report a method to suppress streaming potential using an Ag-coated microfluidic channel on a p-type silicon nanowire (SiNW) array measured by a multiplexed electrical readout. The metal layer sets a constant electrical potential along the microfluidic channel for a given reference electrode voltage regardless of the flow velocity. Without the Ag layer, the magnitude and sign of the surface potential change on the SiNW depends on the flow velocity, width of the microfluidic channel and the device's location inside the microfluidic channel with respect to the reference electrode. Noise analysis of the SiNW array with and without the Ag coating in the fluidic channel shows that noise frequency peaks, resulting from the operation of a piezoelectric micropump, are eliminated using the Ag layer with two reference electrodes located at inlet and outlet. This strategy presents a simple platform to eliminate the streaming potential and can become a powerful tool for nanoscale potentiometric biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of sub-micrometric metallic hollow-core structures by laser interference lithography

International Nuclear Information System (INIS)

Pérez, Noemí; Tavera, Txaber; Rodríguez, Ainara; Ellman, Miguel; Ayerdi, Isabel; Olaizola, Santiago M.

2012-01-01

Highlights: ► Arrays of hollow-core sub-micrometric structures are fabricated. ► Laser interference lithography is used for the pattering of the resist sacrificial layer. ► The removal of the sacrificial layer gives rise to metallic channels with a maximum crosssectional area of 0.1 μm 2 . ► These structures can be used in nanofluidics. - Abstract: This work presents the fabrication of hollow-core metallic structures with a complete laser interference lithography (LIL) process. A negative photoresist is used as sacrificial layer. It is exposed to the pattern resulting from the interference of two laser beams, which produces a structure of photoresist lines with a period of 600 nm. After development of the resist, platinum is deposited on the samples by DC sputtering and the resist is removed with acetone. The resulting metallic structures consist in a continuous platinum film that replicates the photoresist relief with a hollow core. The cross section of the channels is up to 0.1 μm 2 . The fabricated samples are characterized by FESEM and FIB. This last tool helps to provide a clear picture of the shape and size of the channels. Conveniently dimensioned, this array of metallic submicrometric channels can be used in microfluidic or IC cooling applications.

Development of sacrificial support fixture using deflection analysis

Science.gov (United States)

Ramteke, Ashwini M.; Ashtankar, Kishor M.

2018-04-01

Sacrificial support fixtures are the structures used to hold the part during machining while rotating the part about the fourth axis of CNC machining. In Four axis CNC machining part is held in a indexer which is rotated about the fourth axis of rotation. So using traditional fixturing devices to hold the part during machining such as jigs, v blocks and clamping plates needs a several set ups, manufacturing time which increase the cost associated with it. Since the part is rotated about the axis of rotation in four axis CNC machining so using traditional fixturing devices to hold the part while machining we need to reorient the fixture each time for particular orientation of part about the axis of rotation. So our proposed methodology of fixture design eliminates the cost associate with the complicated fixture design for customized parts which in turn reduces the time of manufacturing of the fixtures. But while designing the layout of the fixtures it is found out that the machining the part using four axis CNC machining the accurate machining of the part is directly proportional to the deflection produced in a part. So to machine an accurate part the deflection produced in a part should be minimum. We assume that the deflection produced in a part is a result of the deflection produced in a sacrificial support fixture while machining. So this paper provides the study of the deflection checking in a part machined using sacrificial support fixture by using FEA analysis.

Mussel byssus-inspired engineering of synergistic nanointerfacial interactions as sacrificial bonds into carbon nanotube-reinforced soy protein/nanofibrillated cellulose nanocomposites: Versatile mechanical enhancement

Science.gov (United States)

Wang, Zhong; Zhao, Shujun; Kang, Haijiao; Zhang, Wei; Zhang, Shifeng; Li, Jianzhang

2018-03-01

Achieving flexible and stretchable biobased nanocomposites combining high strength and toughness is still a very challenging endeavor. Herein, we described a novel and versatile biomimetic design for tough and high-performance TEMPO-oxidized nanofibrillated cellulose (TONFC)/soy protein isolate (SPI) nanocomposites, which are triggered by catechol-mimetic carbon nanotubes (PCT) and iron ions (Fe(III)) to yield a strong yet sacrificial metal-ligand motifs into a chemically cross-linked architecture network. Taking advantage of self-polymerization of catechol-inspired natural tannic acid, PCT nanohybrid was prepared through adhering reactive poly-(tannic acid) (PTA) layer onto surfaces of carbon nanotubes via a simple dip-coating process. The high-functionality PCT induced the formation of the metal-ligand bonds through the ionic coordinates between the catechol groups in PCT and -COOH groups of TONFC skeleton with Fe(III) mediation that mimicked mussel byssus. Upon stretching, this tailored TONFC-Fe(III)-catechol coordination bonds served as sacrificial bonds that preferentially detach prior to the covalent network, which gave rise to efficient energy dissipation that the nanocomposites integrity was survived. As a result of these kind of synergistic interfacial interactions (sacrificial and covalent bonding), the optimal nanocomposite films processed high tensile strength (ca. 11.5 MPa), large elongation (ca. 79.3%), remarkable toughness (ca. 6.9 MJ m-3), and favorable water resistance as well as electrical conductivity. The proposed bioinspired strategy for designing plant protein-based materials enables control over their mechanical performance through the synergistic engineering of sacrificial bonds into the composite interface.

Fabrication of circular microfluidic network in enzymatically-crosslinked gelatin hydrogel

Energy Technology Data Exchange (ETDEWEB)

He, Jiankang, E-mail: jiankanghe@mail.xjtu.edu.cn; Chen, Ruomeng; Lu, Yongjie; Zhan, Li; Liu, Yaxiong; Li, Dichen; Jin, Zhongmin

2016-02-01

It is a huge challenge to engineer vascular networks in vital organ tissue engineering. Although the incorporation of artificial microfluidic network into thick tissue-engineered constructs has shown great promise, most of the existing microfluidic strategies are limited to generate rectangle cross-sectional channels rather than circular vessels in soft hydrogels. Here we present a facile approach to fabricate branched microfluidic network with circular cross-sections in gelatin hydrogels by combining micromolding and enzymatically-crosslinking mechanism. Partially crosslinked hydrogel slides with predefined semi-circular channels were molded, assembled and in situ fully crosslinked to form a seamless and circular microfluidic network. The bonding strength of the resultant gelatin hydrogels was investigated. The morphology and the dimension of the resultant circular channels were characterized using scanning electron microscopy (SEM) and micro-computerized tomography (μCT). Computational fluid dynamic simulation shows that the fabrication error had little effect on the distribution of flow field but affected the maximum velocity in comparison with designed models. The microfluidic gelatin hydrogel facilitates the attachment and spreading of human umbilical endothelial cells (HUVECs) to form a uniform endothelialized layer around the circular channel surface, which successfully exhibited barrier functions. The presented method might provide a simple way to fabricate circular microfluidic networks in biologically-relevant hydrogels to advance various applications of in vitro tissue models, organ-on-a-chip systems and tissue engineering. - Highlights: • A facile method was proposed to build a circular fluidic network in gelatin hydrogel. • The fluidic network is mechanically robust and supports physiological flow. • HUVECs formed endothelialized layer around the channel to express barrier function.

Microfluidic electronics.

Science.gov (United States)

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.

Toughening elastomers with sacrificial bonds and watching them break.

Science.gov (United States)

Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

2014-04-11

Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials.

The influence of Ti and Sr alloying elements on electrochemical properties of aluminum sacrificial anodes

Energy Technology Data Exchange (ETDEWEB)

Saremi, M.; Sina, H.; Keyvani, A.; Emamy, M. [Metallurgy and Materials Department, University of Tehran, P.O. Box 11365/4563, Tehran (Iran)

2004-07-01

Aluminum sacrificial anodes are widely used in cathodic protection of alloys in seawater. The interesting properties due to low specific weight, low electrode potential and high current capacity are often hindered by the presence of a passive oxide film which causes several difficulties in their practical application. In this investigation, the electrochemical behavior of Al- 5Zn-0.02In sacrificial anode is studied in 3 wt. % sodium chloride solution. The experiments focused on the influence of Ti and Sr as alloying elements on electrochemical behavior of aluminum sacrificial anode. Ti and Sr are used in different concentrations from 0.03 to 0.1 wt.% 0.01 to 0.05 wt.%, respectively. NACE efficiency and polarization tests are used in this case. It is shown that by using 0.03 wt.% Ti and 0.01 wt.% Sr as the alloying elements to investigate the anodic behavior of the anodes, homogeneous microstructures are obtained which results in improvement of electrochemical properties of aluminum sacrificial anode such as current capacity and anode efficiency. (authors)

Teo-iconología del poder sacrificial entre los mochica Teo-iconology of sacrificial power among the Moche

Directory of Open Access Journals (Sweden)

Adolfo Chaparro Amaya

2011-12-01

Full Text Available Partiendo de las evidencias icónicas del rasgo predatorio y sus equivalentes narrativos presentes en diferentes piezas de la cultura mochica, el texto busca establecer (i una metodología de aproximación al sacrificio caníbal que tenga en cuenta diversas formas icónicas de ‹escritura›, y (ii una explicación so-ciocósmica de la política sacrificial. Al articular lo escritural y lo político, es posible aportar una nueva perspectiva a la rica discusión que sobre las relaciones entre canibalismo y poder han venido proponiendo los arqueólogos, los semióticos y los antropólogos de las culturas prehispánicas.Based on the iconographic evidences of predation and their narrative equivalents, present in different aspects of the Mochica culture, this essay seeks to establish (i a methodology for approaching the cannibal sacrifice taking into account different forms of iconic ‹writing›; and (ii establish a socio-cosmic explanation to sacrificial politics. By articulating these scriptural and political aspects, the paper will provide a new perspective to the rich discussion on the relationship between cannibalism and power that has been proposed by archaeologists, anthropologists and studies on the semiotic of Prehispanic cultures.

Sodium Exposure Tests on Limestone Concrete Used as Sacrificial Protection Layer in FBR

International Nuclear Information System (INIS)

Parida, F.C.; Das, S.K.; Sharma, A.K.; Rao, P.M.; Ramesh, S.S.; Somayajulu, P.A.; Malarvizhi, B.; Kasinathan, N.

2006-01-01

Hot sodium coming in contact with structural concrete in case of sodium leak in FBR system cause damage as a result of thermo-chemical attack by burning sodium. In addition, release of free and bound water from concrete leads to generation of hydrogen gas, which is explosive in nature. Hence limestone concrete, as sacrificial layer on the structural concrete in FBR, needs to be qualified. Four concrete blocks of dimension 600 mm x 600 mm x 300 mm with 300 mm x 300 mm x 150 mm cavity were cast and subjected to controlled sodium exposure tests. They have composition of ordinary portland cement, water, fine and coarse aggregate of limestone in the ratio of 1: 0.58: 2.547: 3.817. These blocks were subjected to preliminary inspection by ultrasonic pulse velocity technique and rebound hammer tests. Each block was exposed for 30 minutes to about 12 kg of liquid sodium (∼ 120 mm liquid column) at 550 deg. C in open air, after which sodium was sucked back from the cavity of the concrete block into a sodium tank. On-line temperature monitoring was carried out at strategic locations of sodium pool and concrete block. After removing sodium from the cavity and cleaning the surfaces, rebound hammer testing was carried out on each concrete block at the same locations where data were taken earlier at pre-exposed stage. The statistical analysis of rebound hammer data revealed that one of the concrete block alone has undergone damage to the extent of 16%. The loss of mass occurred for all the four blocks varied from 0.6 to 2.4% due to release of water during the test duration. Chemical analysis of sodium in concrete samples collected from cavity floor of each block helped in generation of depth profiles of sodium monoxide concentration for each block. From this it is concluded that a bulk penetration of sodium up to 30 mm depth has taken place. However it was also observed that at few local spots, sodium penetrated into concrete up to 50 mm. Cylindrical core samples of 50 mm x 150

Toughening elastomers with sacrificial bonds and watching them break

NARCIS (Netherlands)

Ducrot, E.; Chen, Y.; Bulters, M.J.H.; Sijbesma, R.P.; Creton, C.

2014-01-01

Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4

he sacrificial emplotment of national identity. Pádraic Pearse and the 1916 Easter uprising

Directory of Open Access Journals (Sweden)

Patrick Colm Hogan

2014-06-01

Full Text Available A sense of national identification remains amorphous and inert unless it is cognitively structured and motivationally oriented. Perhaps the most consequential way of structuring and orienting nationalism is through emplotment (organizing in the form of a story. Emplotment commonly follows one of a few cross-culturally recurring genres. In nationalist contexts, the heroic genre—treating military conflict, loss or potential loss, and reasserted sovereignty–is the default form. However, this default may be overridden in particular circumstances. When social devastation precludes heroic achievement, a sacrificial emplotment—treating collective sin, punishment, sacrifice, and redemption—is often particularly salient. Earlier work has examined cases of sacrificial emplotment in its most extreme varieties (treating Hitler and Gandhi. The following essay considers a more ordinary case, the sacrificial nationalism of the prominent Irish anti-colonial revolutionary, Pádraic Pearse, as represented in his plays.

Sacrificial Template-Based Synthesis of Unified Hollow Porous Palladium Nanospheres for Formic Acid Electro-Oxidation

Directory of Open Access Journals (Sweden)

Xiaoyu Qiu

2015-06-01

Full Text Available Large scale syntheses of uniform metal nanoparticles with hollow porous structure have attracted much attention owning to their high surface area, abundant active sites and relatively efficient catalytic activity. Herein, we report a general method to synthesize hollow porous Pd nanospheres (Pd HPNSs by templating sacrificial SiO2 nanoparticles with the assistance of polyallylamine hydrochloride (PAH through layer-by-layer self-assembly. The chemically inert PAH is acting as an efficient stabilizer and complex agent to control the synthesis of Pd HPNSs, probably accounting for its long aliphatic alkyl chains, excellent coordination capability and good hydrophilic property. The physicochemical properties of Pd HPNSs are thoroughly characterized by various techniques, such as transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The growth mechanism of Pd HPNSs is studied based on the analysis of diverse experimental observations. The as-prepared Pd HPNSs exhibit clearly enhanced electrocatalytic activity and durability for the formic oxidation reaction (FAOR in acid medium compared with commercial Pd black.

Cleaning graphene with a titanium sacrificial layer

International Nuclear Information System (INIS)

Joiner, C. A.; Roy, T.; Hesabi, Z. R.; Vogel, E. M.; Chakrabarti, B.

2014-01-01

Graphene is a promising material for future electronic applications and chemical vapor deposition of graphene on copper is a promising method for synthesizing graphene on the wafer scale. The processing of such graphene films into electronic devices introduces a variety of contaminants which can be difficult to remove. An approach to cleaning residues from the graphene channel is presented in which a thin layer of titanium is deposited via thermal e-beam evaporation and immediately removed. This procedure does not damage the graphene as evidenced by Raman spectroscopy, greatly enhances the electrical performance of the fabricated graphene field effect transistors, and completely removes the chemical residues from the surface of the graphene channel as evidenced by x-ray photoelectron spectroscopy.

Sidetracked by trolleys: Why sacrificial moral dilemmas tell us little (or nothing) about utilitarian judgment.

Science.gov (United States)

Kahane, Guy

2015-01-01

Research into moral decision-making has been dominated by sacrificial dilemmas where, in order to save several lives, it is necessary to sacrifice the life of another person. It is widely assumed that these dilemmas draw a sharp contrast between utilitarian and deontological approaches to morality, and thereby enable us to study the psychological and neural basis of utilitarian judgment. However, it has been previously shown that some sacrificial dilemmas fail to present a genuine contrast between utilitarian and deontological options. Here, I raise deeper problems for this research paradigm. Even when sacrificial dilemmas present a contrast between utilitarian and deontological options at a philosophical level, it is misleading to interpret the responses of ordinary folk in these terms. What is currently classified as "utilitarian judgment" does not in fact share essential features of a genuine utilitarian outlook, and is better explained in terms of commonsensical moral notions. When subjects deliberate about such dilemmas, they are not deciding between opposing utilitarian and deontological solutions, but engaging in a richer process of weighing opposing moral reasons. Sacrificial dilemmas therefore tell us little about utilitarian decision-making. An alternative approach to studying proto-utilitarian tendencies in everyday moral thinking is proposed.

Fabrication of sub-micrometric metallic hollow-core structures by laser interference lithography

Energy Technology Data Exchange (ETDEWEB)

Perez, Noemi; Tavera, Txaber [CEIT and Tecnun (University of Navarra) Manuel de Lardizabal 15, 20018 San Sebastian (Spain); Rodriguez, Ainara [CIC Microgune, Paseo Mikeletegi 48, 20009 San Sebastian (Spain); Ellman, Miguel; Ayerdi, Isabel; Olaizola, Santiago M. [CEIT and Tecnun (University of Navarra) Manuel de Lardizabal 15, 20018 San Sebastian (Spain)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Arrays of hollow-core sub-micrometric structures are fabricated. Black-Right-Pointing-Pointer Laser interference lithography is used for the pattering of the resist sacrificial layer. Black-Right-Pointing-Pointer The removal of the sacrificial layer gives rise to metallic channels with a maximum crosssectional area of 0.1 {mu}m{sup 2}. Black-Right-Pointing-Pointer These structures can be used in nanofluidics. - Abstract: This work presents the fabrication of hollow-core metallic structures with a complete laser interference lithography (LIL) process. A negative photoresist is used as sacrificial layer. It is exposed to the pattern resulting from the interference of two laser beams, which produces a structure of photoresist lines with a period of 600 nm. After development of the resist, platinum is deposited on the samples by DC sputtering and the resist is removed with acetone. The resulting metallic structures consist in a continuous platinum film that replicates the photoresist relief with a hollow core. The cross section of the channels is up to 0.1 {mu}m{sup 2}. The fabricated samples are characterized by FESEM and FIB. This last tool helps to provide a clear picture of the shape and size of the channels. Conveniently dimensioned, this array of metallic submicrometric channels can be used in microfluidic or IC cooling applications.

Hot utilitarianism and cold deontology: Insights from a response patterns approach to sacrificial and real world dilemmas.

Science.gov (United States)

Rosas, Alejandro; Viciana, Hugo; Caviedes, Esteban; Arciniegas, Alejandra

2018-04-18

Research on moral judgment with moral dilemmas suggests that "utilitarian" responses (UR) to sacrificial high-conflict dilemmas are due to decreased harm aversion, not only in individuals with clinical conditions, but also in healthy participants with high scores in antisocial personality traits. We investigated the patterns of responses to different dilemma types in healthy participants and present evidence that some URs to sacrificial dilemmas are morally motivated, as indicated by their empathic concern (EC) or primary psychopathy (PP) scores. In study 1 (N = 230) we tested students with four categories of sacrificial dilemmas featuring innocent victims. In study 2 (N = 590) we tested students with two categories of sacrificial dilemmas and two "real-world" moral dilemmas, where the agent can improve the lot of strangers by making a personal sacrifice. Results in both studies showed no decreased harm aversion in a pattern where the only UR is to the sacrificial dilemma where the number of saved people is very high, and significantly lower harm aversion only in the pattern of all-deontological respondents in Study 2. The analysis by response patterns allowed a better discrimination of the moral motivations of participants and showed that at least some of them express moral concerns in their URs.

Microfluidics: A New Layer of Control for Extrusion-Based 3D Printing

Directory of Open Access Journals (Sweden)

Ludovic Serex

2018-02-01

Full Text Available Advances in 3D printing have enabled the use of this technology in a growing number of fields, and have started to spark the interest of biologists. Having the particularity of being cell friendly and allowing multimaterial deposition, extrusion-based 3D printing has been shown to be the method of choice for bioprinting. However as biologically relevant constructs often need to be of high resolution and high complexity, new methods are needed, to provide an improved level of control on the deposited biomaterials. In this paper, we demonstrate how microfluidics can be used to add functions to extrusion 3D printers, which widens their field of application. Micromixers can be added to print heads to perform the last-second mixing of multiple components just before resin dispensing, which can be used for the deposition of new polymeric or composite materials, as well as for bioprinting new materials with tailored properties. The integration of micro-concentrators in the print heads allows a significant increase in cell concentration in bioprinting. The addition of rapid microfluidic switching as well as resolution increase through flow focusing are also demonstrated. Those elementary implementations of microfluidic functions for 3D printing pave the way for more complex applications enabling new prospects in 3D printing.

Dye-Sensitized Photocatalytic Water Splitting and Sacrificial Hydrogen Generation: Current Status and Future Prospects

Directory of Open Access Journals (Sweden)

Pankaj Chowdhury

2017-05-01

Full Text Available Today, global warming and green energy are important topics of discussion for every intellectual gathering all over the world. The only sustainable solution to these problems is the use of solar energy and storing it as hydrogen fuel. Photocatalytic and photo-electrochemical water splitting and sacrificial hydrogen generation show a promise for future energy generation from renewable water and sunlight. This article mainly reviews the current research progress on photocatalytic and photo-electrochemical systems focusing on dye-sensitized overall water splitting and sacrificial hydrogen generation. An overview of significant parameters including dyes, sacrificial agents, modified photocatalysts and co-catalysts are provided. Also, the significance of statistical analysis as an effective tool for a systematic investigation of the effects of different factors and their interactions are explained. Finally, different photocatalytic reactor configurations that are currently in use for water splitting application in laboratory and large scale are discussed.

Wax-bonding 3D microfluidic chips

KAUST Repository

Gong, Xiuqing; Yi, Xin; Xiao, Kang; Li, Shunbo; Kodzius, Rimantas; Qin, Jianhua; Wen, Weijia

2013-01-01

We report a simple, low-cost and detachable microfluidic chip incorporating easily accessible paper, glass slides or other polymer films as the chip materials along with adhesive wax as the recycling bonding material. We use a laser to cut through the paper or film to form patterns and then sandwich the paper and film between glass sheets or polymer membranes . The hot-melt adhesive wax can realize bridge bonding between various materials, for example, paper, polymethylmethacrylate (PMMA) film, glass sheets, or metal plate. The bonding process is reversible and the wax is reusable through a melting and cooling process. With this process, a three-dimensional (3D) microfluidic chip is achievable by vacuating and venting the chip in a hot-water bath. To study the biocompatibility and applicability of the wax-based microfluidic chip, we tested the PCR compatibility with the chip materials first. Then we applied the wax-paper based microfluidic chip to HeLa cell electroporation (EP ). Subsequently, a prototype of a 5-layer 3D chip was fabricated by multilayer wax bonding. To check the sealing ability and the durability of the chip, green fluorescence protein (GFP) recombinant Escherichia coli (E. coli) bacteria were cultured, with which the chemotaxis of E. coli was studied in order to determine the influence of antibiotic ciprofloxacin concentration on the E. coli migration.

Wax-bonding 3D microfluidic chips

KAUST Repository

Gong, Xiuqing

2013-10-10

We report a simple, low-cost and detachable microfluidic chip incorporating easily accessible paper, glass slides or other polymer films as the chip materials along with adhesive wax as the recycling bonding material. We use a laser to cut through the paper or film to form patterns and then sandwich the paper and film between glass sheets or polymer membranes . The hot-melt adhesive wax can realize bridge bonding between various materials, for example, paper, polymethylmethacrylate (PMMA) film, glass sheets, or metal plate. The bonding process is reversible and the wax is reusable through a melting and cooling process. With this process, a three-dimensional (3D) microfluidic chip is achievable by vacuating and venting the chip in a hot-water bath. To study the biocompatibility and applicability of the wax-based microfluidic chip, we tested the PCR compatibility with the chip materials first. Then we applied the wax-paper based microfluidic chip to HeLa cell electroporation (EP ). Subsequently, a prototype of a 5-layer 3D chip was fabricated by multilayer wax bonding. To check the sealing ability and the durability of the chip, green fluorescence protein (GFP) recombinant Escherichia coli (E. coli) bacteria were cultured, with which the chemotaxis of E. coli was studied in order to determine the influence of antibiotic ciprofloxacin concentration on the E. coli migration.

Development of sacrificial specimen for fatigue damage prediction of structure (2nd report); Kozobutsu no hiro sonsho yochi no tameno giseishikenhen no kaihatsu ( 2 )

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Y.; Huang, F.; Hada, K.; Sato, A.; Hamada, K.; Iwata, M. [Hiroshima Univ. (Japan)

1998-12-31

The study aims at applying the sacrificial specimen developed by the authors of the paper on practical structures, the sacrificial specimens are secured to a smooth specimen and a boxing welded joint, and fatigue tests are performed under varying stress amplitude. The load is cyclic 8 stage block load that has load frequency distribution similar to exponential distribution. Then, a fatigue life prediction of structural element is studied based on monitoring results of the sacrificial specimen. The obtained results are as follows. The sacrificial specimen shows steady fatigue property without occurrence of peeling off or buckling even under varying stress amplitude. A limited accumulated damage value of the sacrificial specimen is obtained under the varying stress amplitude. While arranging the crack growth curve of the varying sacrificial specimen in N/Nf, they show almost the same shape not depending on the life. The prediction method of fatigue life of a structure is described based on monitoring results of the sacrificial specimen. 9 refs., 16 figs., 2 tabs.

Three-Dimensional Printing Based Hybrid Manufacturing of Microfluidic Devices.

Science.gov (United States)

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

2015-05-01

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

Sidetracked by trolleys: Why sacrificial moral dilemmas tell us little (or nothing) about utilitarian judgment

Science.gov (United States)

Kahane, Guy

2015-01-01

Research into moral decision-making has been dominated by sacrificial dilemmas where, in order to save several lives, it is necessary to sacrifice the life of another person. It is widely assumed that these dilemmas draw a sharp contrast between utilitarian and deontological approaches to morality, and thereby enable us to study the psychological and neural basis of utilitarian judgment. However, it has been previously shown that some sacrificial dilemmas fail to present a genuine contrast between utilitarian and deontological options. Here, I raise deeper problems for this research paradigm. Even when sacrificial dilemmas present a contrast between utilitarian and deontological options at a philosophical level, it is misleading to interpret the responses of ordinary folk in these terms. What is currently classified as “utilitarian judgment” does not in fact share essential features of a genuine utilitarian outlook, and is better explained in terms of commonsensical moral notions. When subjects deliberate about such dilemmas, they are not deciding between opposing utilitarian and deontological solutions, but engaging in a richer process of weighing opposing moral reasons. Sacrificial dilemmas therefore tell us little about utilitarian decision-making. An alternative approach to studying proto-utilitarian tendencies in everyday moral thinking is proposed. PMID:25791902

Dissolved oxygen sensing using organometallic dyes deposited within a microfluidic environment

Science.gov (United States)

Chen, Q. L.; Ho, H. P.; Jin, L.; Chu, B. W.-K.; Li, M. J.; Yam, V. W.-W.

2008-02-01

This work primarily aims to integrate dissolved oxygen sensing capability with a microfluidic platform containing arrays of micro bio-reactors or bio-activity indicators. The measurement of oxygen concentration is of significance for a variety of bio-related applications such as cell culture and gene expression. Optical oxygen sensors based on luminescence quenching are gaining much interest in light of their low power consumption, quick response and high analyte sensitivity in comparison to similar oxygen sensing devices. In our microfluidic oxygen sensor device, a thin layer of oxygen-sensitive luminescent organometallic dye is covalently bonded to a glass slide. Micro flow channels are formed on the glass slide using patterned PDMS (Polydimethylsiloxane). Dissolved oxygen sensing is then performed by directing an optical excitation probe beam to the area of interest within the microfluidic channel. The covalent bonding approach for sensor layer formation offers many distinct advantages over the physical entrapment method including minimizing dye leaching, ensuring good stability and fabrication simplicity. Experimental results confirm the feasibility of the device.

Fabrication of polyimide based microfluidic channels for biosensor devices

Science.gov (United States)

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

2015-03-01

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

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

Science.gov (United States)

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.

Is Self-Sacrificial Competitive Altruism Primarily a Male Activity?

Directory of Open Access Journals (Sweden)

Francis T. McAndrew

2012-01-01

Full Text Available This study explored the basis of self-sacrificial prosocial behavior in small groups. Seventy-eight undergraduates (39M, 39F filled out a thirty-item personality scale and then participated in a “group problem-solving study” in which the monetary success of a three-person group depended upon one of its members volunteering to endure pain (a cold stressor test and inconvenience (being soaked in a dunk tank. There were 13 groups consisting of two females and one male, and 13 groups consisting of two males and one female. Across groups, the behavior of the altruist was judged to be more costly, challenging, and important and he/she was liked better, rewarded with more money, and preferred as a future experimental partner. Groups containing two males showed more evidence of competition to become altruists than groups containing two females, and personality traits were more effective predictors of altruistic behavior in males than in females. We conclude that competition between males and “showing off” are key factors in triggering self-sacrificial altruistic behavior.

Sidetracked by trolleys: Why sacrificial moral dilemmas tell us little (or nothing) about utilitarian judgment

OpenAIRE

Kahane, Guy

2015-01-01

Research into moral decision-making has been dominated by sacrificial dilemmas where, in order to save several lives, it is necessary to sacrifice the life of another person. It is widely assumed that these dilemmas draw a sharp contrast between utilitarian and deontological approaches to morality, and thereby enable us to study the psychological and neural basis of utilitarian judgment. However, it has been previously shown that some sacrificial dilemmas fail to present a genuine contrast be...

Nanostructured submicron block copolymer dots by sacrificial stamping: a potential preconcentration platform for locally resolved sensing, chemistry and cellular interactions

OpenAIRE

Hou, Peilong; Han, Weijia; Philippi, Michael; Schäfer, Helmut; Steinhart, Martin

2018-01-01

Classical contact lithography involves patterning of surfaces by embossing or by transfer of ink. We report direct lithographic transfer of parts of sacrificial stamps onto counterpart surfaces. Using sacrificial stamps consisting of the block copolymer polystyrene-block-poly(2-pyridine) (PS-b-P2VP), we deposited arrays of nanostructured submicron PS-b-P2VP dots with heights of about 100 nm onto silicon wafers and glass slides. The sacrificial PS-b-P2VP stamps were topographically patterned w...

Fabrication of monolithic microfluidic channels in diamond with ion beam lithography

Science.gov (United States)

Picollo, F.; Battiato, A.; Boarino, L.; Ditalia Tchernij, S.; Enrico, E.; Forneris, J.; Gilardino, A.; Jakšić, M.; Sardi, F.; Skukan, N.; Tengattini, A.; Olivero, P.; Re, A.; Vittone, E.

2017-08-01

In the present work, we report on the monolithic fabrication by means of ion beam lithography of hollow micro-channels within a diamond substrate, to be employed for microfluidic applications. The fabrication strategy takes advantage of ion beam induced damage to convert diamond into graphite, which is characterized by a higher reactivity to oxidative etching with respect to the chemically inert pristine structure. This phase transition occurs in sub-superficial layers thanks to the peculiar damage profile of MeV ions, which mostly damage the target material at their end of range. The structures were obtained by irradiating commercial CVD diamond samples with a micrometric collimated C+ ion beam at three different energies (4 MeV, 3.5 MeV and 3 MeV) at a total fluence of 2 × 1016 cm-2. The chosen multiple-energy implantation strategy allows to obtain a thick box-like highly damaged region ranging from 1.6 μm to 2.1 μm below the sample surface. High-temperature annealing was performed to both promote the graphitization of the ion-induced amorphous layer and to recover the pristine crystalline structure in the cap layer. Finally, the graphite was removed by ozone etching, obtaining monolithic microfluidic structures. These prototypal microfluidic devices were tested injecting aqueous solutions and the evidence of the passage of fluids through the channels was confirmed by confocal fluorescent microscopy.

Microfluidic Dye Lasers

DEFF Research Database (Denmark)

Kristensen, Anders; Balslev, Søren; Gersborg-Hansen, Morten

2006-01-01

A technology for miniaturized, polymer based lasers, suitable for integration with planar waveguides and microfluidic networks is presented. The microfluidic dye laser device consists of a microfluidic channel with an embedded optical resonator. The devices are fabricated in a thin polymer film...

Dual light-activated microfluidic pumps based on an optopiezoelectric composite

International Nuclear Information System (INIS)

Wang, Hsin-Hu; Lee, Chih-Kung; Hsu, Yu-Hsiang; Wu, Ting-Jui; Cheng, I-Chun; Lin, Shih-Jue; Gu, Jen-Tau

2017-01-01

In this paper, a new type of microfluidic pump that can be activated and controlled by a masked light source is presented. The actuation of this micropump is based on an optopiezoelectric composite. This composite is constructed by having one of the electrodes of a piezoelectric PVDF (polyvinylidene fluoride) polymer replaced by a layer of TiOPc (titanyl phthalocyanine) photoconductive coating and an ITO (indium-tin-oxide) transparent electrode. This layer of photoconductive electrode provides the capability to activate multiple locations of this optopiezoelectric composite independently using a masked light source and a single voltage source. To verify the feasibility of this concept, dual light-activated microfluidic pumps based on this optopiezoelectric composite are implemented and studied. Experimental results verify that two microfluidic pumps can be created by one optopiezoelectric composite and that each pump can be optically turned on and off independently or be turned on simultaneously. These results suggest that integrating an optopiezoelectric composite into a lab-on-a-chip system can reduce the size and the number of driving units significantly, since every operation can be done optically and only one driving source is needed. The equivalent circuit, design, and implementation of dual light-activated optopiezoelectric micropumps are discussed in this paper. (paper)

Identification of microfluidic two-phase flow patterns in lab-on-chip devices.

Science.gov (United States)

Yang, Zhaochu; Dong, Tao; Halvorsen, Einar

2014-01-01

This work describes a capacitive sensor for identification of microfluidic two-phase flow in lab-on-chip devices. With interdigital electrodes and thin insulation layer utilized, this sensor is capable of being integrated with the microsystems easily. Transducing principle and design considerations are presented with respect to the microfluidic gas/liquid flow patterns. Numerical simulation results verify the operational principle. And the factors affecting the performance of the sensor are discussed. Besides, a feasible process flow for the fabrication is also proposed.

Microfluidic sieve valves

Science.gov (United States)

Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

2015-01-13

Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

A small-scale, rolled-membrane microfluidic artificial lung designed towards future large area manufacturing.

Science.gov (United States)

Thompson, A J; Marks, L H; Goudie, M J; Rojas-Pena, A; Handa, H; Potkay, J A

2017-03-01

Artificial lungs have been used in the clinic for multiple decades to supplement patient pulmonary function. Recently, small-scale microfluidic artificial lungs (μAL) have been demonstrated with large surface area to blood volume ratios, biomimetic blood flow paths, and pressure drops compatible with pumpless operation. Initial small-scale microfluidic devices with blood flow rates in the μ l/min to ml/min range have exhibited excellent gas transfer efficiencies; however, current manufacturing techniques may not be suitable for scaling up to human applications. Here, we present a new manufacturing technology for a microfluidic artificial lung in which the structure is assembled via a continuous "rolling" and bonding procedure from a single, patterned layer of polydimethyl siloxane (PDMS). This method is demonstrated in a small-scale four-layer device, but is expected to easily scale to larger area devices. The presented devices have a biomimetic branching blood flow network, 10  μ m tall artificial capillaries, and a 66  μ m thick gas transfer membrane. Gas transfer efficiency in blood was evaluated over a range of blood flow rates (0.1-1.25 ml/min) for two different sweep gases (pure O 2 , atmospheric air). The achieved gas transfer data closely follow predicted theoretical values for oxygenation and CO 2 removal, while pressure drop is marginally higher than predicted. This work is the first step in developing a scalable method for creating large area microfluidic artificial lungs. Although designed for microfluidic artificial lungs, the presented technique is expected to result in the first manufacturing method capable of simply and easily creating large area microfluidic devices from PDMS.

Digital Microfluidic System with Vertical Functionality

Directory of Open Access Journals (Sweden)

Brian F. Bender

2015-11-01

Full Text Available Digital (droplet microfluidics (DµF is a powerful platform for automated lab-on-a-chip procedures, ranging from quantitative bioassays such as RT-qPCR to complete mammalian cell culturing. The simple MEMS processing protocols typically employed to fabricate DµF devices limit their functionality to two dimensions, and hence constrain the applications for which these devices can be used. This paper describes the integration of vertical functionality into a DµF platform by stacking two planar digital microfluidic devices, altering the electrode fabrication process, and incorporating channels for reversibly translating droplets between layers. Vertical droplet movement was modeled to advance the device design, and three applications that were previously unachievable using a conventional format are demonstrated: (1 solutions of calcium dichloride and sodium alginate were vertically mixed to produce a hydrogel with a radially symmetric gradient in crosslink density; (2 a calcium alginate hydrogel was formed within the through-well to create a particle sieve for filtering suspensions passed from one layer to the next; and (3 a cell spheroid formed using an on-chip hanging-drop was retrieved for use in downstream processing. The general capability of vertically delivering droplets between multiple stacked levels represents a processing innovation that increases DµF functionality and has many potential applications.

Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates

Science.gov (United States)

Melechko, Anatoli V [Oak Ridge, TN; McKnight, Timothy E [Greenback, TN; Guillorn, Michael A [Ithaca, NY; Ilic, Bojan [Ithaca, NY; Merkulov, Vladimir I [Knoxville, TX; Doktycz, Mitchel J [Knoxville, TN; Lowndes, Douglas H [Knoxville, TN; Simpson, Michael L [Knoxville, TN

2012-03-27

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoconduit material coupled to a surface of the substrate. The substrate defines an aperture and the nanoconduit material defines a nanoconduit that is i) contiguous with the aperture and ii) aligned substantially non-parallel to a plane defined by the surface of the substrate.

Integration of reconfigurable potentiometric electrochemical sensors into a digital microfluidic platform.

Science.gov (United States)

Farzbod, Ali; Moon, Hyejin

2018-05-30

This paper presents the demonstration of on-chip fabrication of a potassium-selective sensor array enabled by electrowetting on dielectric digital microfluidics for the first time. This demonstration proves the concept that electrochemical sensors can be seamlessly integrated with sample preparation units in a digital microfluidic platform. More significantly, the successful on-chip fabrication of a sensor array indicates that sensors become reconfigurable and have longer lifetime in a digital microfluidic platform. The on-chip fabrication of ion-selective electrodes includes electroplating Ag followed by forming AgCl layer by chemical oxidation and depositing a thin layer of desired polymer-based ion selective membrane on one of the sensor electrodes. In this study, potassium ionophores work as potassium ion channels and make the membrane selective to potassium ions. This selectiveness results in the voltage difference across the membrane layer, which is correlated with potassium ion concentration. The calibration curve of the fabricated potassium-selective electrode demonstrates the slope of 58 mV/dec for potassium concentration in KCl sample solutions and shows good agreement with the ideal Nernstian response. The proposed sensor platform is an outstanding candidate for a portable home-use for continuous monitoring of ions thanks to its advantages such as easy automation of sample preparation and detection processes, elongated sensor lifetime, minimal membrane and sample consumption, and user-definable/reconfigurable sensor array. Copyright © 2018 Elsevier B.V. All rights reserved.

Prototyping of Microfluidic Systems with Integrated Waveguides in Cyclin Olefin Copolymer

DEFF Research Database (Denmark)

Bundgaard, Frederik

2007-01-01

, in a collaboration with IMTEK in Freiburg, Germany, an optical detection principle was developed. Using the principle of total internal reflection of a laser beam incident on a fluidic channel, detection of air bubbles is possible. The principle was used on a rotating platform as well as on non-moving systems....... the substrate, optical layers and the lid in the microfluidic systems. • Thermal bonding of polymer structures, including roll lamination of foil onto substrates. • Laser bonding of two polymer layers, including transparent on black, and transparent on transparent with a particle doped spin coating. • Thermal...... treatment of waveguides to improve the surface roughness and lower the propagation loss. The fabrication methods have been characterised, and have been optimised to minimise parameters like fabrication time, surface roughness and interface bonding strength. Using these fabrication methods, microfluidic...

Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management.

Directory of Open Access Journals (Sweden)

Kevin A Wood

Full Text Available Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i food quantity, (ii food quality, and (iii the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems.

Atomic layer deposited oxide films as protective interface layers for integrated graphene transfer

Science.gov (United States)

Cabrero-Vilatela, A.; Alexander-Webber, J. A.; Sagade, A. A.; Aria, A. I.; Braeuninger-Weimer, P.; Martin, M.-B.; Weatherup, R. S.; Hofmann, S.

2017-12-01

The transfer of chemical vapour deposited graphene from its parent growth catalyst has become a bottleneck for many of its emerging applications. The sacrificial polymer layers that are typically deposited onto graphene for mechanical support during transfer are challenging to remove completely and hence leave graphene and subsequent device interfaces contaminated. Here, we report on the use of atomic layer deposited (ALD) oxide films as protective interface and support layers during graphene transfer. The method avoids any direct contact of the graphene with polymers and through the use of thicker ALD layers (≥100 nm), polymers can be eliminated from the transfer-process altogether. The ALD film can be kept as a functional device layer, facilitating integrated device manufacturing. We demonstrate back-gated field effect devices based on single-layer graphene transferred with a protective Al2O3 film onto SiO2 that show significantly reduced charge trap and residual carrier densities. We critically discuss the advantages and challenges of processing graphene/ALD bilayer structures.

A novel technology: microfluidic devices for microbubble ultrasound contrast agent generation.

Science.gov (United States)

Lin, Hangyu; Chen, Junfang; Chen, Chuanpin

2016-09-01

Microbubbles are used as ultrasound contrast agents, which enhance ultrasound imaging techniques. In addition, microbubbles currently show promise in disease therapeutics. Microfluidic devices have increased the ability to produce microbubbles with precise size, and high monodispersity compared to microbubbles created using traditional methods. This paper will review several variations in microfluidic device structures used to produce microbubbles as ultrasound contrast agents. Microfluidic device structures include T-junction, and axisymmetric and asymmetric flow-focusing. These devices have made it possible to produce microbubbles that can enter the vascular space; these microbubbles must be less than 10 μm in diameter and have high monodispersity. For different demands of microbubbles production rate, asymmetric flow-focusing devices were divided into individual and integrated devices. In addition, asymmetric flow-focusing devices can produce double layer and multilayer microbubbles loaded with drug or biological components. Details on the mechanisms of both bubble formation and device structures are provided. Finally, microfluidically produced microbubble acoustic responses, microbubble stability, and microbubble use in ultrasound imaging are discussed.

Inexpensive, rapid prototyping of microfluidic devices using overhead transparencies and a laser print, cut and laminate fabrication method.

Science.gov (United States)

Thompson, Brandon L; Ouyang, Yiwen; Duarte, Gabriela R M; Carrilho, Emanuel; Krauss, Shannon T; Landers, James P

2015-06-01

We describe a technique for fabricating microfluidic devices with complex multilayer architectures using a laser printer, a CO2 laser cutter, an office laminator and common overhead transparencies as a printable substrate via a laser print, cut and laminate (PCL) methodology. The printer toner serves three functions: (i) it defines the microfluidic architecture, which is printed on the overhead transparencies; (ii) it acts as the adhesive agent for the bonding of multiple transparency layers; and (iii) it provides, in its unmodified state, printable, hydrophobic 'valves' for fluidic flow control. By using common graphics software, e.g., CorelDRAW or AutoCAD, the protocol produces microfluidic devices with a design-to-device time of ∼40 min. Devices of any shape can be generated for an array of multistep assays, with colorimetric detection of molecular species ranging from small molecules to proteins. Channels with varying depths can be formed using multiple transparency layers in which a CO2 laser is used to remove the polyester from the channel sections of the internal layers. The simplicity of the protocol, availability of the equipment and substrate and cost-effective nature of the process make microfluidic devices available to those who might benefit most from expedited, microscale chemistry.

The upcoming 3D-printing revolution in microfluidics

Science.gov (United States)

Bhattacharjee, Nirveek; Urrios, Arturo; Kang, Shawn; Folch, Albert

2016-01-01

In the last two decades, the vast majority of microfluidic systems have been built in poly(dimethylsiloxane) (PDMS) by soft lithography, a technique based on PDMS micromolding. A long list of key PDMS properties have contributed to the success of soft lithography: PDMS is biocompatible, elastomeric, transparent, gas-permeable, water-impermeable, fairly inexpensive, copyright-free, and rapidly prototyped with high precision using simple procedures. However, the fabrication process typically involves substantial human labor, which tends to make PDMS devices difficult to disseminate outside of research labs, and the layered molding limits the 3D complexity of the devices that can be produced. 3D-printing has recently attracted attention as a way to fabricate microfluidic systems due to its automated, assembly-free 3D fabrication, rapidly decreasing costs, and fast-improving resolution and throughput. Resins with properties approaching those of PDMS are being developed. Here we review past and recent efforts in 3D-printing of microfluidic systems. We compare the salient features of PDMS molding with those of 3D-printing and we give an overview of the critical barriers that have prevented the adoption of 3D-printing by microfluidic developers, namely resolution, throughput, and resin biocompatibility. We also evaluate the various forces that are persuading researchers to abandon PDMS molding in favor of 3D-printing in growing numbers. PMID:27101171

A smartphone controlled handheld microfluidic liquid handling system.

Science.gov (United States)

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.

Monitoring the Startup of a Sacrificial Concrete Sewer for Odor Control

DEFF Research Database (Denmark)

Nielsen, Asbjørn Haaning; Vollertsen, Jes

2014-01-01

with extended retention time. For the purpose of the study, a 50-m long sacrificial concrete gravity sewer was constructed using a high alkalinity concrete pipe. The monitoring campaign reported in this paper covers the first 9 months of operation. The results clearly demonstrate the ability of the system...

Microfluidic monitoring of programmed cell death in living plant seed tissue

DEFF Research Database (Denmark)

Mark, Christina; Heiskanen, Arto; Zor, Kinga

, et al., (2006), BioEssays, 28, p. 1091). Microfluidic cell culture enables in vitro experiments to approach in vivo conditions. Combining microfluidics with the Lab-On-a-Chip concept allows implementing a wide range of assays for real-time monitoring of effects in a biological system of factors...... such as concentration of selected compounds, external pH, oxygen consumption, redox state and cell viability. The aleurone layer of the barley seed is a 2-3 single cell type thick tissue that can be dissected from the embryo and starchy endosperm. During incubation in vitro this mechanically very robust maintains...

Easy fabrication of high quality nickel mold for deep polymer microfluidic channels

International Nuclear Information System (INIS)

Wong, Ten It; Tan, Christina Yuan Ling; Zhou, Xiaodong; Limantoro, Julian; Fong, Kin Phang; Quan, Chenggen; Sun, Ling Ling

2016-01-01

Mass fabrication of disposable microfluidic chips with hot embossing is a key technology for microfluidic chip based biosensors. In this work, we develop a new method of fabricating high quality and highly durable nickel molds for hot embossing polymer chips. The process involves the addition of a thick, patterned layer of negative photoresist AZ-125nxT to a 4″ silicon wafer, followed by nickel electroplating and delamination of the nickel mold. Our investigations found that compared to a pillar mask, a hole mask can minimize the diffraction effect in photolithography of a thick photoresist, reduce the adhesion of the AZ-125nxT to the photomask in photolithography, and facilitate clean development of the photoresist patterns. By optimizing the hot embossing and chip bonding parameters, microfluidic chips with deep channels are achieved. (paper)

Laser micromachined wax-covered plastic paper as both sputter deposition shadow masks and deep-ultraviolet patterning masks for polymethylmethacrylate-based microfluidic systems

KAUST Repository

Fan, Yiqiang

2013-12-16

We report a technically innovative method of fabricating masks for both deep-ultraviolet (UV) patterning and metal sputtering on polymethylmethacrylate (PMMA) for microfluidic systems. We used a CO2 laser system to cut the required patterns on wax-covered plastic paper; the laser-patterned wax paper will either work as a mask for deep-UV patterning or as a mask for metal sputtering. A microfluidic device was also fabricated to demonstrate the feasibility of this method. The device has two layers: the first layer is a 1-mm thick PMMA substrate that was patterned by deep-UV exposure to create microchannels. The mask used in this process was the laser-cut wax paper. The second layer, also a 1-mm thick PMMA layer, was gold sputtered with patterned wax paper as the shadow mask. These two pieces of PMMA were then bonded to form microchannels with exposed electrodes. This process is a simple and rapid method for creating integrated microfluidic systems that do not require cleanroom facilities.

In situ ZnO-PVA nanocomposite coated microfluidic chips for biosensing

DEFF Research Database (Denmark)

Habouti, S.; Kunstmann-Olsen, C.; Hoyland, J. D.

2014-01-01

Microfluidic chips with integrated fluid and optical connectors have been generated via a simple PDMS master-mould technique. In situ coating using a Zinc oxide polyvinylalcohol based sol-gel method results in ultrathin nanocomposite layers on the fluid channels, which makes them strongly...

Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology.

Science.gov (United States)

Radonić, Vasa; Birgermajer, Slobodan; Kitić, Goran

2017-04-18

In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG) sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor's operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG) structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM) 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene-methanol mixture where various concentrations of toluene were analysed.

Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology

Directory of Open Access Journals (Sweden)

Vasa Radonić

2017-04-01

Full Text Available In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor’s operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene–methanol mixture where various concentrations of toluene were analysed.

Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

DEFF Research Database (Denmark)

Stöhr, Frederik; Michael-Lindhard, Jonas; Hübner, Jörg

2015-01-01

This article describes the realization of complex high-aspect ratio silicon structures with feature dimensions from 100 lm to 100nm by deep reactive ion etching using the Bosch process. As the exact shape of the sidewall profiles can be crucial for the proper functioning of a device, the authors...... of the sacrificial structures was accomplished by thermal oxidation and subsequent selective wet etching. The effects of the dimensions and relative placement of sacrificial walls and pillars on the etching result were determined through systematic experiments. The authors applied this process for exact sidewall...

Dual-nozzle microfluidic droplet generator

Science.gov (United States)

Choi, Ji Wook; Lee, Jong Min; Kim, Tae Hyun; Ha, Jang Ho; Ahrberg, Christian D.; Chung, Bong Geun

2018-05-01

The droplet-generating microfluidics has become an important technique for a variety of applications ranging from single cell analysis to nanoparticle synthesis. Although there are a large number of methods for generating and experimenting with droplets on microfluidic devices, the dispensing of droplets from these microfluidic devices is a challenge due to aggregation and merging of droplets at the interface of microfluidic devices. Here, we present a microfluidic dual-nozzle device for the generation and dispensing of uniform-sized droplets. The first nozzle of the microfluidic device is used for the generation of the droplets, while the second nozzle can accelerate the droplets and increase the spacing between them, allowing for facile dispensing of droplets. Computational fluid dynamic simulations were conducted to optimize the design parameters of the microfluidic device.

Multi-depth valved microfluidics for biofilm segmentation

International Nuclear Information System (INIS)

Meyer, M T; Bentley, W E; Ghodssi, R; Subramanian, S; Kim, Y W; Ben-Yoav, H; Gnerlich, M; Gerasopoulos, K

2015-01-01

Bacterial biofilms present a societal challenge, as they occur in the majority of infections but are highly resistant to both immune mechanisms and traditional antibiotics. In the pursuit of better understanding biofilm biology for developing new treatments, there is a need for streamlined, controlled platforms for biofilm growth and evaluation. We leverage advantages of microfluidics to develop a system in which biofilms are formed and sectioned, allowing parallel assays on multiple sections of one biofilm. A microfluidic testbed with multiple depth profiles was developed to accommodate biofilm growth and sectioning by hydraulically actuated valves. In realization of the platform, a novel fabrication technique was developed for creating multi-depth microfluidic molds using sequentially patterned photoresist separated and passivated by conformal coatings using atomic layer deposition. Biofilm thickness variation within three separately tested devices was less than 13% of the average thickness in each device, while variation between devices was 23% of the average thickness. In a demonstration of parallel experiments performed on one biofilm within one device, integrated valves were used to trisect the uniform biofilms with one section maintained as a control, and two sections exposed to different concentrations of sodium dodecyl sulfate. The technology presented here for multi-depth microchannel fabrication can be used to create a host of microfluidic devices with diverse architectures. While this work focuses on one application of such a device in biofilm sectioning for parallel experimentation, the tailored architectures enabled by the fabrication technology can be used to create devices that provide new biological information. (paper)

Multi-depth valved microfluidics for biofilm segmentation

Science.gov (United States)

Meyer, M. T.; Subramanian, S.; Kim, Y. W.; Ben-Yoav, H.; Gnerlich, M.; Gerasopoulos, K.; Bentley, W. E.; Ghodssi, R.

2015-09-01

Bacterial biofilms present a societal challenge, as they occur in the majority of infections but are highly resistant to both immune mechanisms and traditional antibiotics. In the pursuit of better understanding biofilm biology for developing new treatments, there is a need for streamlined, controlled platforms for biofilm growth and evaluation. We leverage advantages of microfluidics to develop a system in which biofilms are formed and sectioned, allowing parallel assays on multiple sections of one biofilm. A microfluidic testbed with multiple depth profiles was developed to accommodate biofilm growth and sectioning by hydraulically actuated valves. In realization of the platform, a novel fabrication technique was developed for creating multi-depth microfluidic molds using sequentially patterned photoresist separated and passivated by conformal coatings using atomic layer deposition. Biofilm thickness variation within three separately tested devices was less than 13% of the average thickness in each device, while variation between devices was 23% of the average thickness. In a demonstration of parallel experiments performed on one biofilm within one device, integrated valves were used to trisect the uniform biofilms with one section maintained as a control, and two sections exposed to different concentrations of sodium dodecyl sulfate. The technology presented here for multi-depth microchannel fabrication can be used to create a host of microfluidic devices with diverse architectures. While this work focuses on one application of such a device in biofilm sectioning for parallel experimentation, the tailored architectures enabled by the fabrication technology can be used to create devices that provide new biological information.

Differential white cell count by centrifugal microfluidics.

Energy Technology Data Exchange (ETDEWEB)

Sommer, Gregory Jon; Tentori, Augusto M.; Schaff, Ulrich Y.

2010-07-01

We present a method for counting white blood cells that is uniquely compatible with centrifugation based microfluidics. Blood is deposited on top of one or more layers of density media within a microfluidic disk. Spinning the disk causes the cell populations within whole blood to settle through the media, reaching an equilibrium based on the density of each cell type. Separation and fluorescence measurement of cell types stained with a DNA dye is demonstrated using this technique. The integrated signal from bands of fluorescent microspheres is shown to be proportional to their initial concentration in suspension. Among the current generation of medical diagnostics are devices based on the principle of centrifuging a CD sized disk functionalized with microfluidics. These portable 'lab on a disk' devices are capable of conducting multiple assays directly from a blood sample, embodied by platforms developed by Gyros, Samsung, and Abaxis. [1,2] However, no centrifugal platform to date includes a differential white blood cell count, which is an important metric complimentary to diagnostic assays. Measuring the differential white blood cell count (the relative fraction of granulocytes, lymphocytes, and monocytes) is a standard medical diagnostic technique useful for identifying sepsis, leukemia, AIDS, radiation exposure, and a host of other conditions that affect the immune system. Several methods exist for measuring the relative white blood cell count including flow cytometry, electrical impedance, and visual identification from a stained drop of blood under a microscope. However, none of these methods is easily incorporated into a centrifugal microfluidic diagnostic platform.

Numerical simulation of the throwing power of cathodic prevention applied to marine reinforced concrete piles by means of sacrificial anodes

Energy Technology Data Exchange (ETDEWEB)

Bertolini, Luca; Redaelli, Elena [Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica ' G. Natta' , Via Mancinelli, 7, 20131 Milan (Italy)

2004-07-01

The paper deals with the determination of current and potential distribution in reinforced concrete elements partially submerged in seawater aimed at predicting the throwing power of cathodic prevention applied by means of sacrificial anodes. Previous laboratory studies carried out on reinforced concrete columns 15 cm x 15 cm x 120 cm showed that the use of sacrificial anodes placed in the solution at the bottom of the column could provide protection of corroding steel bars in the emerged part of the pile up to about 60 cm from the water level. However, if sacrificial anodes were applied when the concrete was chloride free and steel bars were still passive, even the highest bar, placed at 1 m from the level of water, was protected. This is due to the higher polarizability of passive steel, that makes the throwing power of cathodic prevention higher compared to that of cathodic protection. In order to extend the results obtained on small-scale specimens to elements of higher dimensions, numerical simulations of current and potential distribution were carried out. Two-dimensional models were set up of reinforced concrete piles containing steel bars at different heights protected with sacrificial anodes placed in the water in which they were partially submerged. Boundary conditions describing the electrochemical behaviour of bars were obtained from polarisation curves measured on the previously mentioned columns. Values of concrete conductivity at different heights from the water level were also obtained from those tests. Several cases were considered, representative of conditions differing in electrochemical behaviour of steel bars, dimensions of element, position of sacrificial anodes. The paper discusses the results obtained from the models and compares them in terms of the throwing power that can be reached by using sacrificial anodes immersed in the seawater to protect reinforcing steel bars in the emerged part of a pile. (authors)

Microfluidic monitoring of programmed cell death in living plant seed tissue

DEFF Research Database (Denmark)

Mark, Christina; Heiskanen, Arto; Zor, Kinga

highly specific responses to the phytohormones gibberellic acid and abscisic acid. Combined with the increasing usage as a model for studying plant protein secretion, these properties make the aleurone layer ideal for maintenance in a microfluidics system (Fath, Angelika, et al., (2001), Plant Physiol...

MICROFLUIDIC COMPONENT CAPABLE OF SELF-SEALING

DEFF Research Database (Denmark)

2009-01-01

A microfluidic component (100) for building a microfluidic system is provided. The microfluidic component (100) can be mounted on a microf luidic breadboard (202) in a manner that allows it to be connected to other microfluidic components (204, 206) without the requirement of additional devices....... The microfluidic component (100) comprises at least one flexible tube piece (102) for transporting a fluid. The microfluidic component (100) also comprises means for applying and maintaining pressure (104) between the flexible tube piece (102) and a tube piece (208, 210) housed in another microfluidic component...

Teo-iconology of sacrificial power among the Moche

OpenAIRE

Chaparro Amaya, Adolfo

2011-01-01

Partiendo de las evidencias icónicas del rasgo predatorio y sus equivalentes narrativos presentes en diferentes piezas de la cultura mochica, el texto busca establecer (i) una metodología de aproximación al sacrificio caníbal que tenga en cuenta diversas formas icónicas de ‹escritura›, y (ii) una explicación so-ciocósmica de la política sacrificial. Al articular lo escritural y lo político, es posible aportar una nueva perspectiva a la rica discusión que sobre las relaciones entre...

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

Science.gov (United States)

Jarujareet, Ungkarn; Amarit, Rattasart; Sumriddetchkajorn, Sarun

2016-11-01

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

Prototyping chips in minutes: Direct Laser Plotting (DLP) of functional microfluidic structures

KAUST Repository

Wang, Limu; Kodzius, Rimantas; Yi, Xin; Li, Shunbo; Hui, Yu Sanna; Wen, Weijia

2013-01-01

and bio-compatible polymer films by manipulating the strength and density of laser pulses. With the DLP technique, chip-embedded micro-electrodes, micro-mixers and 3D microfluidic chips with 5 layers, which normally require several days of work in a

Prototyping chips in minutes: Direct Laser Plotting (DLP) of functional microfluidic structures

KAUST Repository

Wang, Limu

2013-10-10

We report a fast and simple prototyping method to fabricate polymer-based microfluidic chips using Direct Laser Plotting (DLP) technique, by which various functional micro-structures can be realized within minutes, in a mask-free and out-of-cleanroom fashion. A 2D Computer-Aid-Design (CAD) software was employed to layout the required micro-structures and micro-channels, a CO2 laser plotter was then used to construct the microstructures. The desired patterns can be plotted directly on PDMS substrates and bio-compatible polymer films by manipulating the strength and density of laser pulses. With the DLP technique, chip-embedded micro-electrodes, micro-mixers and 3D microfluidic chips with 5 layers, which normally require several days of work in a cleanroom facility, can be fabricated in minutes in common laboratory. This novel method can produce microfluidic channels with average feature size of 100 μm, while feature size of 50 μm or smaller is achievable by making use of the interference effect from laser impulsion. In this report, we present the optimized parameters for successful fabrication of 3D microchannels, micro-mixers and microfluidic chips for protein concentration measurements (Bovine Serum Albumine (BSA) test), and a novel procedure to pattern flexible embedding electrodes on PDMS-based microfluidic chips. DLP offers a convenient and low cost alternative to conventional microfluidic channel fabrication technique which relies on complicated and hazardous soft lithography process.

Tunable Microfluidic Dye Laser

DEFF Research Database (Denmark)

Olsen, Brian Bilenberg; Helbo, Bjarne; Kutter, Jörg Peter

2003-01-01

We present a tunable microfluidic dye laser fabricated in SU-8. The tunability is enabled by integrating a microfluidic diffusion mixer with an existing microfluidic dye laser design by Helbo et al. By controlling the relative flows in the mixer between a dye solution and a solvent......, the concentration of dye in the laser cavity can be adjusted, allowing the wavelength to be tuned. Wavelength tuning controlled by the dye concentration was demonstrated with macroscopic dye lasers already in 1971, but this principle only becomes practically applicable by the use of microfluidic mixing...

A facile alternative technique for large-area graphene transfer via sacrificial polymer

Directory of Open Access Journals (Sweden)

Eric Auchter

2017-12-01

Full Text Available A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated the effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.

Bioinspired Layer-by-Layer Microcapsules Based on Cellulose Nanofibers with Switchable Permeability

DEFF Research Database (Denmark)

Paulraj, Thomas; Riazanova, Anastasia V; Yao, Kun

2017-01-01

Green, all-polysaccharide based microcapsules with mechanically robust capsule walls and fast, stimuli-triggered, and switchable permeability behavior show great promise in applications based on selective and timed permeability. Taking a cue from nature, the build-up and composition of plant......-by-layer technique on sacrificial CaCO3 templates, using plant polysaccharides (pectin, cellulose nanofibers, and xyloglucan) only. In water, the capsule wall was permeable to labeled dextrans with a hydrodynamic diameter of ∼6.6 nm. Upon exposure to NaCl, the porosity of the capsule wall quickly changed allowing...

Microfluidics on liquid handling stations (μF-on-LHS): a new industry-compatible microfluidic platform

Science.gov (United States)

Kittelmann, Jörg; Radtke, Carsten P.; Waldbaur, Ansgar; Neumann, Christiane; Hubbuch, Jürgen; Rapp, Bastian E.

2014-03-01

Since the early days microfluidics as a scientific discipline has been an interdisciplinary research field with a wide scope of potential applications. Besides tailored assays for point-of-care (PoC) diagnostics, microfluidics has been an important tool for large-scale screening of reagents and building blocks in organic chemistry, pharmaceutics and medical engineering. Furthermore, numerous potential marketable products have been described over the years. However, especially in industrial applications, microfluidics is often considered only an alternative technology for fluid handling, a field which is industrially mostly dominated by large-scale numerically controlled fluid and liquid handling stations. Numerous noteworthy products have dominated this field in the last decade and have been inhibited the widespread application of microfluidics technology. However, automated liquid handling stations and microfluidics do not have to be considered as mutually exclusive approached. We have recently introduced a hybrid fluidic platform combining an industrially established liquid handling station and a generic microfluidic interfacing module that allows probing a microfluidic system (such as an essay or a synthesis array) using the instrumentation provided by the liquid handling station. We term this technology "Microfluidic on Liquid Handling Stations (μF-on-LHS)" - a classical "best of both worlds"- approach that allows combining the highly evolved, automated and industry-proven LHS systems with any type of microfluidic assay. In this paper we show, to the best of our knowledge, the first droplet microfluidics application on an industrial LHS using the μF-on-LHS concept.

Passive microfluidic array card and reader

Science.gov (United States)

Dugan, Lawrence Christopher [Modesto, CA; Coleman, Matthew A [Oakland, CA

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.

Microfluidic desalination : capacitive deionization on chip for microfluidic sample preparation

NARCIS (Netherlands)

Roelofs, Susan Helena

2015-01-01

The main aim of the work described in this thesis is to implement the desalination technique capacitive deionization (CDI) on a microfluidic chip to improve the reproducibility in the analysis of biological samples for drug development. Secondly, microfluidic CDI allows for the in situ study of ion

Bridging Flows: Microfluidic End‐User Solutions

DEFF Research Database (Denmark)

Sabourin, David

Microfluidic applications hold promise for many different end‐users both within and outside, and across many different research communities. Despite the benefits of microfluidic approaches, adoption and implementation thereof is often hindered by practical issues. Microfluidic components which......‐integrated interconnection and miniaturized peristaltic pump solutions were then combined into modular microfluidic systems. One system provides high interconnection numbers/density and allows many possible configurations. Additionally, and apart from many other accounts of modular microfluidic solutions, methods...... for control and actuation of microfluidic networks built from the modular components is described. Prototypes of the microfluidic system have begun to be distributed to external collaborators and researcher parties. These end‐users will assist in the validation of the approach and ultimately fulfil the key...

Finite element modeling simulation-assisted design of integrated microfluidic chips for heavy metal ion stripping analysis

International Nuclear Information System (INIS)

Hong, Ying; Zou, Jianhua; Ge, Gang; Xiao, Wanyue; Shao, Jinjun; Dong, Xiaochen; Gao, Ling

2017-01-01

In this article, a transparent integrated microfluidic device composed of a 3D-printed thin-layer flow cell (3D-PTLFC) and an S-shaped screen-printed electrode (SPE) has been designed and fabricated for heavy metal ion stripping analysis. A finite element modeling (FEM) simulation is employed to optimize the shape of the electrode, the direction of the inlet pipeline, the thin-layer channel height and the sample flow rate to enhance the electron-enrichment efficiency for stripping analysis. The results demonstrate that the S-shaped SPE configuration matches the channel in 3D-PTLFC perfectly for the anodic stripping behavior of the heavy metal ions. Under optimized conditions, a wide linear range of 1–80 µ g l −1 is achieved for Pb 2+ detection with a limit of 0.3 µ g l −1 for the microfluidic device. Thus, the obtained integrated microfluidic device proves to be a promising approach for heavy metal ions stripping analysis with low cost and high performance. (paper)

A full-wafer fabrication process for glass microfluidic chips with integrated electroplated electrodes by direct bonding of dry film resist

International Nuclear Information System (INIS)

Vulto, Paul; Urban, G A; Huesgen, Till; Albrecht, Björn

2009-01-01

A full-wafer process is presented for fast and simple fabrication of glass microfluidic chips with integrated electroplated electrodes. The process employs the permanent dry film resist (DFR) Ordyl SY300 to create microfluidic channels, followed by electroplating of silver and subsequent chlorination. The dry film resist is bonded directly to a second substrate, without intermediate gluing layers, only by applying pressure and moderate heating. The process of microfluidic channel fabrication, electroplating and wafer bonding can be completed within 1 day, thus making it one of the fastest and simplest full-wafer fabrication processes. (note)

Three-dimensional parallelization of microfluidic droplet generators for a litre per hour volume production of single emulsions

KAUST Repository

Conchouso Gonzalez, David

2014-01-01

This paper looks at the design, fabrication and characterization of stackable microfluidic emulsion generators, with coefficients of variation as low as ~6% and with production rates as high as ~1 L h-1. This work reports the highest throughput reported in the literature for a microfluidic device with simultaneous operation of liquid-liquid droplet generators. The device was achieved by stacking several layers of 128 flow-focusing droplet generators, organized in a circular array. These layers are interconnected via through-holes and fed with designated fractal distribution networks. The proposed layers were milled on poly(methylmethacrylate) (PMMA) sheets and the stack was thermo-compression bonded to create a three-dimensional device with a high density of generators and an integrated hydraulic manifold. The effect of stacking multiple layers was studied and the results show that fabrication accuracy has a greater impact on the dispersity of the emulsion than the addition of more layers to the stack. Particle crystallization of drugs was also demonstrated as a possible application of this technology in industry. © 2014 the Partner Organisations.

Automated microfluidic devices integrating solid-phase extraction, fluorescent labeling, and microchip electrophoresis for preterm birth biomarker analysis.

Science.gov (United States)

Sahore, Vishal; Sonker, Mukul; Nielsen, Anna V; Knob, Radim; Kumar, Suresh; Woolley, Adam T

2018-01-01

We have developed multichannel integrated microfluidic devices for automated preconcentration, labeling, purification, and separation of preterm birth (PTB) biomarkers. We fabricated multilayer poly(dimethylsiloxane)-cyclic olefin copolymer (PDMS-COC) devices that perform solid-phase extraction (SPE) and microchip electrophoresis (μCE) for automated PTB biomarker analysis. The PDMS control layer had a peristaltic pump and pneumatic valves for flow control, while the PDMS fluidic layer had five input reservoirs connected to microchannels and a μCE system. The COC layers had a reversed-phase octyl methacrylate porous polymer monolith for SPE and fluorescent labeling of PTB biomarkers. We determined μCE conditions for two PTB biomarkers, ferritin (Fer) and corticotropin-releasing factor (CRF). We used these integrated microfluidic devices to preconcentrate and purify off-chip-labeled Fer and CRF in an automated fashion. Finally, we performed a fully automated on-chip analysis of unlabeled PTB biomarkers, involving SPE, labeling, and μCE separation with 1 h total analysis time. These integrated systems have strong potential to be combined with upstream immunoaffinity extraction, offering a compact sample-to-answer biomarker analysis platform. Graphical abstract Pressure-actuated integrated microfluidic devices have been developed for automated solid-phase extraction, fluorescent labeling, and microchip electrophoresis of preterm birth biomarkers.

Ice matrix in reconfigurable microfluidic systems

Energy Technology Data Exchange (ETDEWEB)

Bossi, A M [Department of Biotechnology, University of Verona, Strada Le Grazie 15, I-37134, Verona (Italy); Vareijka, M; Piletska, E V; Turner, A P F; Piletsky, S A [Cranfield Health, Cranfield University, Vincent Building B52, Cranfield, Bedfordshire, MK43 0AL (United Kingdom); Meglinski, I [Department of Physics, University of Otago, PO Box 56, Dunedin, 9054 (New Zealand)

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. (paper)

Ice matrix in reconfigurable microfluidic systems

International Nuclear Information System (INIS)

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

2013-01-01

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. (paper)

Ice matrix in reconfigurable microfluidic systems

Science.gov (United States)

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.

Wirelessly powered micro-tracer enabled by miniaturized antenna and microfluidic channel

International Nuclear Information System (INIS)

Duan, G; Zhao, X; Seren, H R; Chen, C; Zhang, X

2015-01-01

A miniaturized antenna, 380μm by 380μm in size, was fabricated and integrated with a commercialized passive RFID chip to form a micro-tracer, whose size was 2mm by 1mm in total. The micro-tracer was wirelessly powered and interrogated by a single layer spiral reader antenna through near field coupling. To maximize the working distance, the resonant frequency of micro-tracer and reader antenna were matched at 840MHz. Due to the ultra small size of the tracer antenna, power transfer efficiency decreased dramatically as the distance between tracer antenna and reader antenna increased, thus the working distance of the microtracer was limited within 1mm. To achieve massive operation of the micro-tracer, a microfluidic platform was fabricated with in channel focusing and separation. Acrylic sheets were laser cut to define the channel and cover structure, then bonded together layer by layer with a glass substrate, on which reader antenna was integrated. Pump oil was used as the fluidic media carrying the micro-tracer flowing inside the microfluidic channel. The wireless power transfer and real-time communication was demonstrated with the micro-tracer flowing above the reader antenna, as the ID of the micro-tracer was retrieved and displayed on a computer screen. (paper)

Biodistance analysis of the Moche sacrificial victims from Huaca de la Luna plaza 3C: Matrix method test of their origins.

Science.gov (United States)

Sutter, Richard C; Verano, John W

2007-02-01

The purpose of this study is to test two competing models regarding the origins of Early Intermediate Period (AD 200-750) sacrificial victims from the Huacas de Moche site using the matrix correlation method. The first model posits the sacrificial victims represent local elites who lost competitions in ritual battles with one another, while the other model suggests the victims were nonlocal warriors captured during warfare with nearby polities. We estimate biodistances for sacrificial victims from Huaca de la Luna Plaza 3C (AD 300-550) with eight previously reported samples from the north coast of Peru using both the mean measure of divergence (MMD) and Mahalanobis' distance (d2). Hypothetical matrices are developed based upon the assumptions of each of the two competing models regarding the origins of Moche sacrificial victims. When the MMD matrix is compared to the two hypothetical matrices using a partial-Mantel test (Smouse et al.: Syst Zool 35 (1986) 627-632), the ritual combat model (i.e. local origins) has a low and nonsignificant correlation (r = 0.134, P = 0.163), while the nonlocal origins model is highly correlated and significant (r = 0.688, P = 0.001). Comparisons of the d2 results and the two hypothetical matrices also produced low and nonsignificant correlation for the ritual combat model (r = 0.210, P = 0.212), while producing a higher and statistically significant result with the nonlocal origins model (r = 0.676, P = 0.002). We suggest that the Moche sacrificial victims represent nonlocal warriors captured in territorial combat with nearby competing polities. Copyright 2006 Wiley-Liss, Inc.

In situ ZnO-PVA nanocomposite coated microfluidic chips for biosensing

Science.gov (United States)

Habouti, Salah; Kunstmann-Olsen, Casper; Hoyland, James D.; Rubahn, Horst-Günter; Es-Souni, Mohammed

2014-05-01

Microfluidic chips with integrated fluid and optical connectors have been generated via a simple PDMS master-mould technique. In situ coating using a Zinc oxide polyvinylalcohol based sol-gel method results in ultrathin nanocomposite layers on the fluid channels, which makes them strongly hydrophilic and minimizes auto contamination of the chips by injected fluorescent biomarkers.

Microfluidic CODES: a scalable multiplexed electronic sensor for orthogonal detection of particles in microfluidic channels.

Science.gov (United States)

Liu, Ruxiu; Wang, Ningquan; Kamili, Farhan; Sarioglu, A Fatih

2016-04-21

Numerous biophysical and biochemical assays rely on spatial manipulation of particles/cells as they are processed on lab-on-a-chip devices. Analysis of spatially distributed particles on these devices typically requires microscopy negating the cost and size advantages of microfluidic assays. In this paper, we introduce a scalable electronic sensor technology, called microfluidic CODES, that utilizes resistive pulse sensing to orthogonally detect particles in multiple microfluidic channels from a single electrical output. Combining the techniques from telecommunications and microfluidics, we route three coplanar electrodes on a glass substrate to create multiple Coulter counters producing distinct orthogonal digital codes when they detect particles. We specifically design a digital code set using the mathematical principles of Code Division Multiple Access (CDMA) telecommunication networks and can decode signals from different microfluidic channels with >90% accuracy through computation even if these signals overlap. As a proof of principle, we use this technology to detect human ovarian cancer cells in four different microfluidic channels fabricated using soft lithography. Microfluidic CODES offers a simple, all-electronic interface that is well suited to create integrated, low-cost lab-on-a-chip devices for cell- or particle-based assays in resource-limited settings.

Layer-by-layer cell membrane assembly

Science.gov (United States)

Matosevic, Sandro; Paegel, Brian M.

2013-11-01

Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode

International Nuclear Information System (INIS)

Zaifol Samsu; Muhammad Daud; Siti Radiah Mohd Kamarudin; Nur Ubaidah Saidin; Azali Muhammad; Mohd Shaari Ripin; Rusni Rejab; Mohd Shariff Sattar

2010-01-01

This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

An open-source, programmable pneumatic setup for operation and automated control of single- and multi-layer microfluidic devices

Directory of Open Access Journals (Sweden)

Kara Brower

2018-04-01

Full Text Available Microfluidic technologies have been used across diverse disciplines (e.g. high-throughput biological measurement, fluid physics, laboratory fluid manipulation but widespread adoption has been limited in part due to the lack of openly disseminated resources that enable non-specialist labs to make and operate their own devices. Here, we report the open-source build of a pneumatic setup capable of operating both single and multilayer (Quake-style microfluidic devices with programmable scripting automation. This setup can operate both simple and complex devices with 48 device valve control inputs and 18 sample inputs, with modular design for easy expansion, at a fraction of the cost of similar commercial solutions. We present a detailed step-by-step guide to building the pneumatic instrumentation, as well as instructions for custom device operation using our software, Geppetto, through an easy-to-use GUI for live on-chip valve actuation and a scripting system for experiment automation. We show robust valve actuation with near real-time software feedback and demonstrate use of the setup for high-throughput biochemical measurements on-chip. This open-source setup will enable specialists and novices alike to run microfluidic devices easily in their own laboratories. Keywords: Microfluidics, Pneumatics, Laboratory automation, Biochip, BioMEMs, Biohacking, Fluid handling, Micro total analysis systems (μTAS, Quake-style valves

The effect of zinc (Zn) content to cell potential value and efficiency aluminium sacrificial anode in 0.2 M sulphuric acid environment

Science.gov (United States)

Akranata, Ahmad Ridho; Sulistijono, Awali, Jatmoko

2018-04-01

Sacrificial anode is sacirifial component that used to protect steel from corrosion. Generally, the component are made of aluminium and zinc in water environment. Sacrificial anode change the protected metal structure become cathodic with giving current. The advantages of aluminium is corrosion resistance, non toxicity and easy forming. Zinc generally used for coating in steel to prevent steel from corrosion. This research was conducted to analyze the effect of zinc content to the value of cell potential and efficiency aluminium sacrificial anode with sand casting method in 0.2 M sulphuric acid environment. The sacrificial anode fabrication made with alloying aluminium and zinc metals with variation composition of alloy with pure Al, Al-3Zn, Al-6Zn, and Al-9Zn with open die sand casting process. The component installed with ASTM A36 steel. After the research has been done the result showed that addition of zinc content increase the cell potential, protection efficiency, and anode efficiency from steel plate. Cell potential value measurement and weight loss measurement showed that addition of zinc content increase the cell potential value into more positive that can protected the ASTM A36 steel more efficiently that showed in weight loss measurement where the protection efficiency and anodic efficiency of Al-9Zn sacrificial anode is better than protection efficiency and anodic efficiency of pure Al. The highest protection efficiency gotten by Al-9Zn alloy

Acoustofluidics 14: Applications of acoustic streaming in microfluidic devices.

Science.gov (United States)

Wiklund, Martin; Green, Roy; Ohlin, Mathias

2012-07-21

In part 14 of the tutorial series "Acoustofluidics--exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming.

A vapor feed methanol microfluidic fuel cell with high fuel and energy efficiency

International Nuclear Information System (INIS)

Wang, Yifei; Leung, Dennis Y.C.; Xuan, Jin; Wang, Huizhi

2015-01-01

Highlights: • A microfluidic fuel cell with a vapor feed anode is investigated. • Its advantages include simpler design, direct usage of methanol and better performance. • The prototype achieves a peak power density of 55.4 mW cm −2 under room temperature. • The energy efficiency of 9.4% is much higher than its liquid feed counterpart. - Abstract: In this paper, a prototype of methanol microfluidic fuel cell with vapor feed anode configuration is proposed to improve the fuel and energy efficiency of the conventional liquid feed methanol microfluidic fuel cells. Peak power density of 55.4 mW cm −2 can be achieved with this prototype under room temperature, which is 30% higher than its conventional liquid feed counterpart. Moreover, an energy efficiency of 9.4% is achieved, which is 27.5 times higher than its liquid feed counterpart. This superiority on both cell performance and energy efficiency is directly benefitted from its vapor feed anode configuration, which alleviates the fuel crossover, eliminates the fuel depletion boundary layer, and avoids the bulk anolyte wastage. The tradeoff between cell performance and fuel utilization for conventional liquid feed microfluidic fuel cells is also evaded

Integrated electrofluidic circuits: pressure sensing with analog and digital operation functionalities for microfluidics.

Science.gov (United States)

Wu, Chueh-Yu; Lu, Jau-Ching; Liu, Man-Chi; Tung, Yi-Chung

2012-10-21

Microfluidic technology plays an essential role in various lab on a chip devices due to its desired advantages. An automated microfluidic system integrated with actuators and sensors can further achieve better controllability. A number of microfluidic actuation schemes have been well developed. In contrast, most of the existing sensing methods still heavily rely on optical observations and external transducers, which have drawbacks including: costly instrumentation, professional operation, tedious interfacing, and difficulties of scaling up and further signal processing. This paper reports the concept of electrofluidic circuits - electrical circuits which are constructed using ionic liquid (IL)-filled fluidic channels. The developed electrofluidic circuits can be fabricated using a well-developed multi-layer soft lithography (MSL) process with polydimethylsiloxane (PDMS) microfluidic channels. Electrofluidic circuits allow seamless integration of pressure sensors with analog and digital operation functions into microfluidic systems and provide electrical readouts for further signal processing. In the experiments, the analog operation device is constructed based on electrofluidic Wheatstone bridge circuits with electrical outputs of the addition and subtraction results of the applied pressures. The digital operation (AND, OR, and XOR) devices are constructed using the electrofluidic pressure controlled switches, and output electrical signals of digital operations of the applied pressures. The experimental results demonstrate the designed functions for analog and digital operations of applied pressures are successfully achieved using the developed electrofluidic circuits, making them promising to develop integrated microfluidic systems with capabilities of precise pressure monitoring and further feedback control for advanced lab on a chip applications.

Digital microfluidics: A promising technique for biochemical applications

Science.gov (United States)

Wang, He; Chen, Liguo; Sun, Lining

2017-12-01

Digital microfluidics (DMF) is a versatile microfluidics technology that has significant application potential in the areas of automation and miniaturization. In DMF, discrete droplets containing samples and reagents are controlled to implement a series of operations via electrowetting-on-dielectric. This process works by applying electrical potentials to an array of electrodes coated with a hydrophobic dielectric layer. Unlike microchannels, DMF facilitates precise control over multiple reaction processes without using complex pump, microvalve, and tubing networks. DMF also presents other distinct features, such as portability, less sample consumption, shorter chemical reaction time, flexibility, and easier combination with other technology types. Due to its unique advantages, DMF has been applied to a broad range of fields (e.g., chemistry, biology, medicine, and environment). This study reviews the basic principles of droplet actuation, configuration design, and fabrication of the DMF device, as well as discusses the latest progress in DMF from the biochemistry perspective.

Rapid manufacturing for microfluidics

CSIR Research Space (South Africa)

Land, K

2012-10-01

Full Text Available for microfluidics K. LAND, S. HUGO, M MBANJWA, L FOURIE CSIR Materials Science and Manufacturing P O Box 395, Pretoria 0001, SOUTH AFRICA Email: kland@csir.co.za INTRODUCTION Microfluidics refers to the manipulation of very small volumes of fluid.... Microfluidics is at the forefront of developing solutions for drug discovery, diagnostics (from glucose tests to malaria and TB testing) and environmental diagnostics (E-coli monitoring of drinking water). In order to quickly implement new designs, a rapid...

Commercialization of microfluidic devices.

Science.gov (United States)

Volpatti, Lisa R; Yetisen, Ali K

2014-07-01

Microfluidic devices offer automation and high-throughput screening, and operate at low volumes of consumables. Although microfluidics has the potential to reduce turnaround times and costs for analytical devices, particularly in medical, veterinary, and environmental sciences, this enabling technology has had limited diffusion into consumer products. This article analyzes the microfluidics market, identifies issues, and highlights successful commercialization strategies. Addressing niche markets and establishing compatibility with existing workflows will accelerate market penetration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Methods of making microfluidic devices

KAUST Repository

Buttner, Ulrich

2017-06-01

Microfluidics has advanced in terms of designs and structures, however, fabrication methods are either time consuming or expensive to produce, in terms of the facilities and equipment needed. A fast and economically viable method is provided to allow, for example, research groups to have access to microfluidic fabrication. Unlike most fabrication methods, a method is provided to fabricate a microfluidic device in one step. In an embodiment, a resolution of 50 micrometers was achieved by using maskless high-resolution digital light projection (MDLP). Bonding and channel fabrication of complex or simple structures can be rapidly incorporated to fabricate the microfluidic devices.

Effect of samarium in corrosion and microstructure of Al-5Zn-0.5Cu as low driving voltage sacrificial anode

Science.gov (United States)

Pratesa, Yudha; Ferdian, Deni; Ramadhan, Fajar Yusya; Maulana, Bramuda

2018-05-01

Sacrificial Anode Low voltage is the latest generation of the sacrificial anode that can prevent the occurrence of Hydrogen Cracking (HIC) due to overprotection. The Al-5n-0.5Cu alloy showed the potential to be developed as the new sacrificial anode. However, the main problem is copper made Al2Cu intermetallic in grain boundary. Samarium is added to modify the shape of the intermetallic to make it finer and make the corrosion uniform. Several characterizations were conducted to analyze the effect of Samarium. Scanning electron microscope (SEM) and Energy dispersive spectroscopy was used to analyzed the microstructure of the alloy. Metallography preparation was prepared for SEM analysis. Corrosion behavior was characterized by cyclic polarization in 3.5% NaCl solution. The results show samarium can change the shape of intermetallic and refine the grains. In addition, samarium makes better pitting resistance and exhibits a tendency for uniform corrosion. It is indicated by the loop reduction (ΔEpit-prot). Current density increased as an effect of samarium addition from 6x10-5 Ampere (Al-5Zn-0.5Cu) to 2.5x10-4 Ampere (Al-5Zn-0.5Cu-0.5Sm). Steel potential protection increased after addition of samarium which is an indication the possibility of Al-Zn-Cu-Sm to be used as low voltage sacrificial anode.

Improving the Efficiency Enhancement of Photonic Crystal Based InGaN Solar Cell by Using a GaN Cap Layer

Directory of Open Access Journals (Sweden)

T. F. Gundogdu

2014-01-01

Full Text Available We studied a high indium content (0.8 InGaN based solar cell design where the active InGaN layer is sandwiched between a GaN cap layer and a GaN spacer layer. The incorporation of the sacrificial cap layer allows for the etching of the front surface without removing the active InGaN resulting in a 50% enhancement of the short-circuit current density for a 15 nm-thick InGaN layer.

Fabrication of sacrificial anode cathodic protection through casting method

International Nuclear Information System (INIS)

Mohd Sharif Sattar; Muhamad Daud; Siti Radiah Mohd Kamarudin; Azali Muhamad; Zaiton Selamat; Rusni Rejab

2007-01-01

Aluminum is one of the few metals that can be cast by all of the processes used in casting metals. These processes consist of die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, investment casting, and continuous casting. Other processes such as lost foam, squeeze casting, and hot isostatic pressing are also used. Permanent mold casting method was selected in which used for fabricating of sacrificial anode cathodic protection. This product was ground for surface finished and fabricated in the cylindrical form and reinforced with carbon steel at a center of the anode. (Author)

Hydrogel microfluidics for the patterning of pluripotent stem cells

Science.gov (United States)

Cosson, S.; Lutolf, M. P.

2014-03-01

Biomolecular signaling is of utmost importance in governing many biological processes such as the patterning of the developing embryo where biomolecules regulate key cell-fate decisions. In vivo, these factors are presented in a spatiotemporally tightly controlled fashion. Although state-of-the-art microfluidic technologies allow precise biomolecule delivery in time and space, long-term (stem) cell culture at the micro-scale is often far from ideal due to medium evaporation, limited space for cell growth or shear stress. To overcome these challenges, we here introduce a concept based on hydrogel microfluidics for decoupling conventional, macro-scale cell culture from precise biomolecule delivery through a gel layer. We demonstrate the spatiotemporally controlled neuronal commitment of mouse embryonic stem cells via delivery of retinoic acid gradients. This technique should be useful for testing the effect of dose and timing of biomolecules, singly or in combination, on stem cell fate.

Principles, Techniques, and Applications of Tissue Microfluidics

Science.gov (United States)

Wade, Lawrence A.; Kartalov, Emil P.; Shibata, Darryl; Taylor, Clive

2011-01-01

The principle of tissue microfluidics and its resultant techniques has been applied to cell analysis. Building microfluidics to suit a particular tissue sample would allow the rapid, reliable, inexpensive, highly parallelized, selective extraction of chosen regions of tissue for purposes of further biochemical analysis. Furthermore, the applicability of the techniques ranges beyond the described pathology application. For example, they would also allow the posing and successful answering of new sets of questions in many areas of fundamental research. The proposed integration of microfluidic techniques and tissue slice samples is called "tissue microfluidics" because it molds the microfluidic architectures in accordance with each particular structure of each specific tissue sample. Thus, microfluidics can be built around the tissues, following the tissue structure, or alternatively, the microfluidics can be adapted to the specific geometry of particular tissues. By contrast, the traditional approach is that microfluidic devices are structured in accordance with engineering considerations, while the biological components in applied devices are forced to comply with these engineering presets.

A microfluidic chip containing multiple 3D nanofibrous scaffolds for culturing human pluripotent stem cells

Science.gov (United States)

Wertheim, Lior; Shapira, Assaf; Amir, Roey J.; Dvir, Tal

2018-04-01

In microfluidics-based lab-on-a-chip systems, which are used for investigating the effect of drugs and growth factors on cells, the latter are usually cultured within the device’s channels in two-dimensional, and not in their optimal three-dimensional (3D) microenvironment. Herein, we address this shortfall by designing a microfluidic system, comprised of two layers. The upper layer of the system consists of multiple channels generating a gradient of soluble factors. The lower layer is comprised of multiple wells, each deposited with 3D, nanofibrous scaffold. We first used a mathematical model to characterize the fluid flow within the system. We then show that induced pluripotent stem cells can be seeded within the 3D scaffolds and be exposed to a well-mixed gradient of soluble factors. We believe that utilizing such system may enable in the future to identify new differentiation factors, investigate drug toxicity, and eventually allow to perform analyses on patient-specific tissues, in order to fit the appropriate combination and concentration of drugs.

Computer-aided design of microfluidic very large scale integration (mVLSI) biochips design automation, testing, and design-for-testability

CERN Document Server

Hu, Kai; Ho, Tsung-Yi

2017-01-01

This book provides a comprehensive overview of flow-based, microfluidic VLSI. The authors describe and solve in a comprehensive and holistic manner practical challenges such as control synthesis, wash optimization, design for testability, and diagnosis of modern flow-based microfluidic biochips. They introduce practical solutions, based on rigorous optimization and formal models. The technical contributions presented in this book will not only shorten the product development cycle, but also accelerate the adoption and further development of modern flow-based microfluidic biochips, by facilitating the full exploitation of design complexities that are possible with current fabrication techniques. Offers the first practical problem formulation for automated control-layer design in flow-based microfluidic biochips and provides a systematic approach for solving this problem; Introduces a wash-optimization method for cross-contamination removal; Presents a design-for-testability (DfT) technique that can achieve 100...

AAO-CNTs electrode on microfluidic flow injection system for rapid iodide sensing.

Science.gov (United States)

Phokharatkul, Ditsayut; Karuwan, Chanpen; Lomas, Tanom; Nacapricha, Duangjai; Wisitsoraat, Anurat; Tuantranont, Adisorn

2011-06-15

In this work, carbon nanotubes (CNTs) nanoarrays in anodized aluminum oxide (AAO-CNTs) nanopore is integrated on a microfluidic flow injection system for in-channel electrochemical detection of iodide. The device was fabricated from PDMS (polydimethylsiloxane) microchannel bonded on glass substrates that contains three-electrode electrochemical system, including AAO-CNTs as a working electrode, silver as a reference electrode and platinum as an auxiliary electrode. Aluminum, stainless steel catalyst, silver and platinum layers were sputtered on the glass substrate through shadow masks. Aluminum layer was then anodized by two-step anodization process to form nanopore template. CNTs were then grown in AAO template by thermal chemical vapor deposition. The amperometric detection of iodide was performed in 500-μm-wide and 100-μm-deep microchannels on the microfluidic chip. The influences of flow rate, injection volume and detection potential on the current response were optimized. From experimental results, AAO-CNTs electrode on chip offers higher sensitivity and wider dynamic range than CNTs electrode with no AAO template. Copyright © 2011 Elsevier B.V. All rights reserved.

Inhibitory effect of common microfluidic materials on PCR outcome

KAUST Repository

Kodzius, Rimantas

2012-02-20

compatibility of various materials commonly used while producing microfluidic devices is also pertinent and beneficial to other enzymatic reactions in microfluidic devices. Most PCR-friendly materials exhibit similar signals regardless of the inclusion or not of BSA in the PCR mixture; these materials are PP, PTFE, PDMS, wax (Tm 80°C), SiO2 quartz, pyrex and soda-lime glasses, NOA68, and mineral oil. Our results showed that there was near total adsorption of template DNA when the wax (Tm 60°C) was used (RBI = 9.2×101). In contrast, when NOA61, mineral oil and acrylic glue materials were employed, significant adsorption occurred (RBI < 1.5×103). The polymerase-inhibition experiments indicate that following materials do not have strong effects (RBI > 1.1×103) on polymerase: PC, PP, PTFE, PDMS, silicon with a layer of 560 nm SiO2, SiO2 quartz, pyrex, and soda-lime glass. Slight polymerase inhibition (RBI < 9.2×102) was observed with PMMA, PVC, waxes (Tm 56°C and 80°C), silicon, and NOA68. A very strong or near total inhibition (RBI < 1.8×102) was observed with wax (Tm 60°C), ITO glass, SU-8, NOA61, metal tubes, mineral oil, epoxy, and the acrylic glues. \\tOur results show that material selection for microfluidic PCR chips, which are characterized by large SAVR, is a vital part of optimizing PCR outcome. This study of the inhibitory effect of various common microfluidics materials has provided a new rapid testing method using only a PCR cycler, and it has confirmed and expanded the list of tested materials. The type of PCR compatibility test enables the most effectual choice of materials for use in biology-related experiments.

Self-contained microfluidic systems: a review.

Science.gov (United States)

Boyd-Moss, Mitchell; Baratchi, Sara; Di Venere, Martina; Khoshmanesh, Khashayar

2016-08-16

Microfluidic systems enable rapid diagnosis, screening and monitoring of diseases and health conditions using small amounts of biological samples and reagents. Despite these remarkable features, conventional microfluidic systems rely on bulky expensive external equipment, which hinders their utility as powerful analysis tools outside of research laboratories. 'Self-contained' microfluidic systems, which contain all necessary components to facilitate a complete assay, have been developed to address this limitation. In this review, we provide an in-depth overview of self-contained microfluidic systems. We categorise these systems based on their operating mechanisms into three major groups: passive, hand-powered and active. Several examples are provided to discuss the structure, capabilities and shortcomings of each group. In particular, we discuss the self-contained microfluidic systems enabled by active mechanisms, due to their unique capability for running multi-step and highly controllable diagnostic assays. Integration of self-contained microfluidic systems with the image acquisition and processing capabilities of smartphones, especially those equipped with accessory optical components, enables highly sensitive and quantitative assays, which are discussed. Finally, the future trends and possible solutions to expand the versatility of self-contained, stand-alone microfluidic platforms are outlined.

Microfluidic technology for molecular diagnostics.

Science.gov (United States)

Robinson, Tom; Dittrich, Petra S

2013-01-01

Molecular diagnostics have helped to improve the lives of millions of patients worldwide by allowing clinicians to diagnose patients earlier as well as providing better ongoing therapies. Point-of-care (POC) testing can bring these laboratory-based techniques to the patient in a home setting or to remote settings in the developing world. However, despite substantial progress in the field, there still remain many challenges. Progress in molecular diagnostics has benefitted greatly from microfluidic technology. This chapter aims to summarise the more recent advances in microfluidic-based molecular diagnostics. Sections include an introduction to microfluidic technology, the challenges of molecular diagnostics, how microfluidic advances are working to solve these issues, some alternative design approaches, and detection within these systems.

Microfluidic separation of viruses from blood cells based on intrinsic transport processes.

Science.gov (United States)

Zhao, Chao; Cheng, Xuanhong

2011-09-01

Clinical analysis of acute viral infection in blood requires the separation of viral particles from blood cells, since the cytoplasmic enzyme inhibits the subsequent viral detection. To facilitate this procedure in settings without access to a centrifuge, we present a microfluidic device to continuously purify bionanoparticles from cells based on their different intrinsic movements on the microscale. In this device, a biological sample is layered on top of a physiological buffer, and both fluids are transported horizontally at the same flow rate in a straight channel under laminar flow. While the micron sized particles such as cells sediment to the bottom layer with a predictable terminal velocity, the nanoparticles move vertically by diffusion. As their vertical travel distances have a different dependence on time, the micro- and nanoparticles can preferentially reside in the bottom and top layers respectively after certain residence time, yielding purified viruses. We first performed numerical analysis to predicate the particle separation and then tested the theory using suspensions of synthetic particles and biological samples. The experimental results using dilute synthetic particles closely matched the numerical analysis of a two layer flow system containing different sized particles. Similar purification was achieved using diluted blood spiked with human immunodeficiency virus. However, viral purification in whole blood is compromised due to extensive bioparticle collisions. With the parallelization and automation potential offered by microfluidics, this device has the potential to function as an upstream sample preparation module to continuously provide cell depleted bio-nanoparticles for downstream analysis.

Slopes To Prevent Trapping of Bubbles in Microfluidic Channels

Science.gov (United States)

Greer, Harold E.; Lee, Michael C.; Smith, J. Anthony; Willis, Peter A.

2010-01-01

The idea of designing a microfluidic channel to slope upward along the direction of flow of the liquid in the channel has been conceived to help prevent trapping of gas bubbles in the channel. In the original application that gave rise to this idea, the microfluidic channels are parts of micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. It is necessary to prevent trapping of gas bubbles in these devices because uninterrupted liquid pathways are essential for sustaining the electrical conduction and flows that are essential for CE. The idea is also applicable to microfluidic devices that may be developed for similar terrestrial microCE biotechnological applications or other terrestrial applications in which trapping of bubbles in microfluidic channels cannot be tolerated. A typical microCE device in the original application includes, among other things, multiple layers of borosilicate float glass wafers. Microfluidic channels are formed in the wafers, typically by use of wet chemical etching. The figure presents a simplified cross section of part of such a device in which the CE channel is formed in the lowermost wafer (denoted the channel wafer) and, according to the present innovation, slopes upward into a via hole in another wafer (denoted the manifold wafer) lying immediately above the channel wafer. Another feature of the present innovation is that the via hole in the manifold wafer is made to taper to a wider opening at the top to further reduce the tendency to trap bubbles. At the time of reporting the information for this article, an effort to identify an optimum technique for forming the slope and the taper was in progress. Of the techniques considered thus far, the one considered to be most promising is precision milling by use of femtosecond laser pulses. Other similar techniques that may work equally well are precision milling using a focused ion beam, or a small diamond

Applications of Microfluidics in Quantitative Biology.

Science.gov (United States)

Bai, Yang; Gao, Meng; Wen, Lingling; He, Caiyun; Chen, Yuan; Liu, Chenli; Fu, Xiongfei; Huang, Shuqiang

2018-05-01

Quantitative biology is dedicated to taking advantage of quantitative reasoning and advanced engineering technologies to make biology more predictable. Microfluidics, as an emerging technique, provides new approaches to precisely control fluidic conditions on small scales and collect data in high-throughput and quantitative manners. In this review, the authors present the relevant applications of microfluidics to quantitative biology based on two major categories (channel-based microfluidics and droplet-based microfluidics), and their typical features. We also envision some other microfluidic techniques that may not be employed in quantitative biology right now, but have great potential in the near future. © 2017 Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences. Biotechnology Journal Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Microfluidic device, and related methods

Science.gov (United States)

Wong, Eric W. (Inventor)

2010-01-01

A method of making a microfluidic device is provided. The method features patterning a permeable wall on a substrate, and surrounding the permeable wall with a solid, non-permeable boundary structure to establish a microfluidic channel having a cross-sectional dimension less than 5,000 microns and a cross-sectional area at least partially filled with the permeable wall so that fluid flowing through the microfluidic channel at least partially passes through the permeable wall.

Rapid microfluidic thermal cycler for nucleic acid amplification

Science.gov (United States)

Beer, Neil Reginald; Vafai, Kambiz

2015-10-27

A system for thermal cycling a material to be thermal cycled including a microfluidic heat exchanger; a porous medium in the microfluidic heat exchanger; a microfluidic thermal cycling chamber containing the material to be thermal cycled, the microfluidic thermal cycling chamber operatively connected to the microfluidic heat exchanger; a working fluid at first temperature; a first system for transmitting the working fluid at first temperature to the microfluidic heat exchanger; a working fluid at a second temperature, a second system for transmitting the working fluid at second temperature to the microfluidic heat exchanger; a pump for flowing the working fluid at the first temperature from the first system to the microfluidic heat exchanger and through the porous medium; and flowing the working fluid at the second temperature from the second system to the heat exchanger and through the porous medium.

Microfluidic Apps for off-the-shelf instruments.

Science.gov (United States)

Mark, Daniel; von Stetten, Felix; Zengerle, Roland

2012-07-21

Within the last decade a huge increase in research activity in microfluidics could be observed. However, despite several commercial success stories, microfluidic chips are still not sold in high numbers in mass markets so far. Here we promote a new concept that could be an alternative approach to commercialization: designing microfluidic chips for existing off-the-shelf instruments. Such "Microfluidic Apps" could significantly lower market entry barriers and provide many advantages: developers of microfluidic chips make use of existing equipment or platforms and do not have to develop instruments from scratch; end-users can profit from microfluidics without the need to invest in new equipment; instrument manufacturers benefit from an expanded customer base due to the new applications that can be implemented in their instruments. Microfluidic Apps could be considered as low-cost disposables which can easily be distributed globally via web-shops. Therefore they could be a door-opener for high-volume mass markets.

Microfluidics for chemical processing

NARCIS (Netherlands)

Gardeniers, Johannes G.E.

2006-01-01

Microfluidic systems, and more specifically, microfluidic chips, have a number of features that make them particularly useful for the study of chemical reactions on-line. The present paper will discuss two examples, the study of fluidic behaviour at high pressures and the excitation and detection of

Analysis, design, and constrution of a sacrificial shield wall

International Nuclear Information System (INIS)

Fialkow; Shah, S.B.

1978-01-01

The sacrificial shield wall, a cylindrical enclosure around the reactor pressure vessel (RPV), is a major component of nuclear power plants of the Boiling Water Reactor (BWR) type. A method developed for the analysis and design of such walls is described which eliminates shortcomings in methods used in current practice. The method treats the wall as a space frame of ring beams and columns and includes the skin plates as finite elements. Design loadings, load combinations, and acceptance criteria are presented. Results by this method are furnished and compared with results by an alternate method. Significant design features are described and a narrative of construction procedures is included. (Author)

Cell manipulation in microfluidics

International Nuclear Information System (INIS)

Yun, Hoyoung; Kim, Kisoo; Lee, Won Gu

2013-01-01

Recent advances in the lab-on-a-chip field in association with nano/microfluidics have been made for new applications and functionalities to the fields of molecular biology, genetic analysis and proteomics, enabling the expansion of the cell biology field. Specifically, microfluidics has provided promising tools for enhancing cell biological research, since it has the ability to precisely control the cellular environment, to easily mimic heterogeneous cellular environment by multiplexing, and to analyze sub-cellular information by high-contents screening assays at the single-cell level. Various cell manipulation techniques in microfluidics have been developed in accordance with specific objectives and applications. In this review, we examine the latest achievements of cell manipulation techniques in microfluidics by categorizing externally applied forces for manipulation: (i) optical, (ii) magnetic, (iii) electrical, (iv) mechanical and (v) other manipulations. We furthermore focus on history where the manipulation techniques originate and also discuss future perspectives with key examples where available. (topical review)

Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

Science.gov (United States)

Yu, Xiao-Ying; Liu, Bingwen; Yang, Li; Zhu, Zihua; Marshall, Matthew J.

2016-03-01

A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

'Utilitarian' judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good.

Science.gov (United States)

Kahane, Guy; Everett, Jim A C; Earp, Brian D; Farias, Miguel; Savulescu, Julian

2015-01-01

A growing body of research has focused on so-called 'utilitarian' judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such 'utilitarian' judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between 'utilitarian' judgment in such sacrificial dilemmas and a range of traits, attitudes, judgments and behaviors that either reflect or reject an impartial concern for the greater good of all. In Study 1, we found that rates of 'utilitarian' judgment were associated with a broadly immoral outlook concerning clear ethical transgressions in a business context, as well as with sub-clinical psychopathy. In Study 2, we found that 'utilitarian' judgment was associated with greater endorsement of rational egoism, less donation of money to a charity, and less identification with the whole of humanity, a core feature of classical utilitarianism. In Studies 3 and 4, we found no association between 'utilitarian' judgments in sacrificial dilemmas and characteristic utilitarian judgments relating to assistance to distant people in need, self-sacrifice and impartiality, even when the utilitarian justification for these judgments was made explicit and unequivocal. This lack of association remained even when we controlled for the antisocial element in 'utilitarian' judgment. Taken together, these results suggest that there is very little relation between sacrificial judgments in the hypothetical dilemmas that dominate current research, and a genuine utilitarian approach to ethics. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Preparation of nanoparticles by continuous-flow microfluidics

International Nuclear Information System (INIS)

Jahn, Andreas; Reiner, Joseph E.; Vreeland, Wyatt N.; DeVoe, Don L.; Locascio, Laurie E.; Gaitan, Michael

2008-01-01

We review a variety of micro- and nanoparticle formulations produced with microfluidic methods. A diverse variety of approaches to generate microscale and nanoscale particles has been reported. Here we emphasize the use of microfluidics, specifically microfluidic systems that operate in a continuous flow mode, thereby allowing continuous generation of desired particle formulations. The generation of semiconductor quantum dots, metal colloids, emulsions, and liposomes is considered. To emphasize the potential benefits of the continuous-flow microfluidic methodology for nanoparticle generation, preliminary data on the size distribution of liposomes formed using the microfluidic approach is compared to the traditional bulk alcohol injection method.

Encapsulation of sacrificial silicon containing particles for SH oxide ceramics via a boehmite precursor route

NARCIS (Netherlands)

Carabat, A.L.; Van der Zwaag, S.; Sloof, W.G.

2013-01-01

Easy crack propagation in oxide ceramic coatings limits their application in high temperature environment (e.g. such as engines and gas turbine components) [1]. In order to overcome this problem, incorporation of sacrificial particles into an oxide ceramic coating may be a viable option. Particles

Micro-optics for microfluidic analytical applications.

Science.gov (United States)

Yang, Hui; Gijs, Martin A M

2018-02-19

This critical review summarizes the developments in the integration of micro-optical elements with microfluidic platforms for facilitating detection and automation of bio-analytical applications. Micro-optical elements, made by a variety of microfabrication techniques, advantageously contribute to the performance of an analytical system, especially when the latter has microfluidic features. Indeed the easy integration of optical control and detection modules with microfluidic technology helps to bridge the gap between the macroscopic world and chip-based analysis, paving the way for automated and high-throughput applications. In our review, we start the discussion with an introduction of microfluidic systems and micro-optical components, as well as aspects of their integration. We continue with a detailed description of different microfluidic and micro-optics technologies and their applications, with an emphasis on the realization of optical waveguides and microlenses. The review continues with specific sections highlighting the advantages of integrated micro-optical components in microfluidic systems for tackling a variety of analytical problems, like cytometry, nucleic acid and protein detection, cell biology, and chemical analysis applications.

Microfluidic high gradient magnetic cell separation

Science.gov (United States)

Inglis, David W.; Riehn, Robert; Sturm, James C.; Austin, Robert H.

2006-04-01

Separation of blood cells by native susceptibility and by the selective attachment of magnetic beads has recently been demonstrated on microfluidic devices. We discuss the basic principles of how forces are generated via the magnetic susceptibility of an object and how microfluidics can be combined with micron-scale magnetic field gradients to greatly enhance in principle the fractionating power of magnetic fields. We discuss our efforts and those of others to build practical microfluidic devices for the magnetic separation of blood cells. We also discuss our attempts to integrate magnetic separation with other microfluidic features for developing handheld medical diagnostic tools.

Microfluidic fuel cells and batteries

CERN Document Server

Kjeang, Erik

2014-01-01

Microfluidic fuel cells and batteries represent a special type of electrochemical power generators that can be miniaturized and integrated in a microfluidic chip. Summarizing the initial ten years of research and development in this emerging field, this SpringerBrief is the first book dedicated to microfluidic fuel cell and battery technology for electrochemical energy conversion and storage. Written at a critical juncture, where strategically applied research is urgently required to seize impending technology opportunities for commercial, analytical, and educational utility, the intention is

Immunodetection of salivary biomarkers by an optical microfluidic biosensor with polyethylenimine-modified polythiophene-C70 organic photodetectors.

Science.gov (United States)

Dong, Tao; Pires, Nuno Miguel Matos

2017-08-15

This work reports a novel optical microfluidic biosensor with highly sensitive organic photodetectors (OPDs) for absorbance-based detection of salivary protein biomarkers at the point of care. The compact and miniaturized biosensor has comprised OPDs made of polythiophene-C 70 bulk heterojunction for the photoactive layer; whilst a calcium-free cathode interfacial layer, made of linear polyethylenimine, was incorporated to the photodetectors to enhance the low cost. The OPDs realized onto a glass chip were aligned to antibody-functionalized chambers of a poly(methyl methacrylate) microfluidic chip, in where immunogold-silver assays were conducted. The biosensor has detected IL-8, IL-1β and MMP-8 protein in spiked saliva with high detection specificity and short analysis time exhibiting detection limits between 80pgmL -1 and 120pgmL -1 . The result for IL-8 was below the clinical established cut-off of 600pgmL -1 , which revealed the potential of the biosensor to early detection of oral cancer. The detection limit was also comparable to other previously reported immunosensors performed with bulky instrumentation or using inorganic photodetectors. The optical detection sensitivity of the polythiophene-C 70 OPD was enhanced by optimizing the thickness of the photoactive layer and anode interfacial layer prior to the saliva immunoassays. Further, the biosensor was tested with unspiked human saliva samples, and the results of measuring IL-8 and IL-1β were in statistical agreement with those provided by two commercial assays of ELISA. The optical microfluidic biosensor reported hereby offers an attractive and cost-effective tool to diagnostics or screening purposes at the point of care. Copyright © 2017 Elsevier B.V. All rights reserved.

Practical Packaging Technology for Microfluidic Systems

International Nuclear Information System (INIS)

Lee, Hwan Yong; Han, Song I; Han, Ki Ho

2010-01-01

This paper presents the technology for the design, fabrication, and characterization of a microfluidic system interface (MSI): the purpose of this technology is to enable the integration of complex microfluidic systems. The MSI technology can be applied in a simple manner for realizing complex arrangements of microfluidic interconnects, integrated microvalves for fluid control, and optical windows for on-chip optical processes. A microfluidic system for the preparation of genetic samples was used as the test vehicle to prove the effectiveness of the MSI technology for packaging complex microfluidic systems with multiple functionalities. The miniaturized genetic sample preparation system comprised several functional compartments, including compartments for cell purification, cell separation, cell lysis, solid-phase DNA extraction, polymerase chain reaction, and capillary electrophoresis. Additionally, the functional operation of the solid-phase extraction and PCR thermocycling compartments was demonstrated by using the MSI

RATIONALIZATION OF THE SCHEMA OF SACRIFICIAL ANODES USING FROM THE STANDPOINT OF MATERIAL AND POWER RESOURCES ECONOMY

Directory of Open Access Journals (Sweden)

S. E. Chikilev

2008-01-01

Full Text Available The calculations, allowing to optimize using of sacrificial copper anodes in the process of wire brassing, and also the results of experimental matching of material for insoluble anodes are given.

Multi-layer micro/nanofluid devices with bio-nanovalves

Science.gov (United States)

Li, Hao; Ocola, Leonidas E.; Auciello, Orlando H.; Firestone, Millicent A.

2013-01-01

A user-friendly multi-layer micro/nanofluidic flow device and micro/nano fabrication process are provided for numerous uses. The multi-layer micro/nanofluidic flow device can comprise: a substrate, such as indium tin oxide coated glass (ITO glass); a conductive layer of ferroelectric material, preferably comprising a PZT layer of lead zirconate titanate (PZT) positioned on the substrate; electrodes connected to the conductive layer; a nanofluidics layer positioned on the conductive layer and defining nanochannels; a microfluidics layer positioned upon the nanofluidics layer and defining microchannels; and biomolecular nanovalves providing bio-nanovalves which are moveable from a closed position to an open position to control fluid flow at a nanoscale.

Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

Directory of Open Access Journals (Sweden)

Michael D. Blanton

2012-09-01

Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

Method of Manufacturing A Porous Polymer Component Involving Use of A Dissolvable, Sacrificial Material

DEFF Research Database (Denmark)

2015-01-01

and thereby the resulting inner structure of the component 1 is arranged in a controlled and reproducible manner. The sacrificial material 2 and possibly also the component material 3 may e.g. be arranged by use of a 3D-printer or manually. The method may e.g. be used to manufacture a three...

Graphene nano-ink biosensor arrays on a microfluidic paper for multiplexed detection of metabolites

Energy Technology Data Exchange (ETDEWEB)

Labroo, Pratima; Cui, Yue, E-mail: yue.cui@usu.edu

2014-02-01

Graphical abstract: - Highlights: • We report graphene-ink biosensor arrays on a microfluidic paper for metabolites. • The device is able to detect multiple metabolites sensitively and rapidly. • The device fabrication process is simple and inexpensive. - Abstract: The development of a miniaturized and low-cost platform for the highly sensitive, selective and rapid detection of multiplexed metabolites is of great interest for healthcare, pharmaceuticals, food science, and environmental monitoring. Graphene is a delicate single-layer, two-dimensional network of carbon atoms with extraordinary electrical sensing capability. Microfluidic paper with printing technique is a low cost matrix. Here, we demonstrated the development of graphene-ink based biosensor arrays on a microfluidic paper for the multiplexed detection of different metabolites, such as glucose, lactate, xanthine and cholesterol. Our results show that the graphene biosensor arrays can detect multiple metabolites on a microfluidic paper sensitively, rapidly and simultaneously. The device exhibits a fast measuring time of less than 2 min, a low detection limit of 0.3 μM, and a dynamic detection range of 0.3–15 μM. The process is simple and inexpensive to operate and requires a low consumption of sample volume. We anticipate that these results could open exciting opportunities for a variety of applications.

Research Progress of Microfluidic Chips Preparation and its Optical Element

Directory of Open Access Journals (Sweden)

Feng WANG

2014-03-01

Full Text Available Microfluidic technology is the emerging technologies in researching fluid channel and related applications in the micro and nano-scale space. Microfluidic chip is a new miniaturized rapid analysis platform by microfluidic technology, it has many characteristics such as liquid flow control, minimal reagent consumption, rapid analysis, which is widely used in physics, chemistry, biology, and engineering science and other fields, it has strong interdisciplinary. This paper mainly discusses research progress of materials used for microfluidic chips and the devices based on microfluidic technology, including microfluidic chip, microfluidic optical devices, microfluidic laser preparation, microfluidic chip applications, focusing on the quasi-molecular laser processing technology and femtosecond laser processing technology in the microfluidic devices preparation, and make development prospects for it.

Integrated lenses in polystyrene microfluidic devices

KAUST Repository

Fan, Yiqiang

2013-04-01

This paper reports a new method for integrating microlenses into microfluidic devices for improved observation. Two demonstration microfluidic devices were provided which were fabricated using this new technique. The integrated microlenses were fabricated using a free-surface thermo-compression molding method on a polystyrene (PS) sheet which was then bonded on top of microfluidic channels as a cover plate, with the convex microlenses providing a magnified image of the channel for the easier observation of the flow in the microchannels. This approach for fabricating the integrated microlens in microfluidic devices is rapid, low cost and without the requirement of cleanroom facilities. © 2013 IEEE.

Chemiluminescence generation and detection in a capillary-driven microfluidic chip

Science.gov (United States)

Ramon, Charlotte; Temiz, Yuksel; Delamarche, Emmanuel

2017-02-01

The use of microfluidic technology represents a strong opportunity for providing sensitive, low-cost and rapid diagnosis at the point-of-care and such a technology might therefore support better, faster and more efficient diagnosis and treatment of patients at home and in healthcare settings both in developed and developing countries. In this work, we consider luminescence-based assays as an alternative to well-established fluorescence-based systems because luminescence does not require a light source or expensive optical components and is therefore a promising detection method for point-of-care applications. Here, we show a proof-of-concept of chemiluminescence (CL) generation and detection in a capillary-driven microfluidic chip for potential immunoassay applications. We employed a commercial acridan-based reaction, which is catalyzed by horseradish peroxidase (HRP). We investigated CL generation under flow conditions using a simplified immunoassay model where HRP is used instead of the complete sandwich immunocomplex. First, CL signals were generated in a capillary microfluidic chip by immobilizing HRP on a polydimethylsiloxane (PDMS) sealing layer using stencil deposition and flowing CL substrate through the hydrophilic channels. CL signals were detected using a compact (only 5×5×2.5 cm3) and custom-designed scanner, which was assembled for less than $30 and comprised a 128×1 photodiode array, a mini stepper motor, an Arduino microcontroller, and a 3D-printed housing. In addition, microfluidic chips having specific 30-μm-deep structures were fabricated and used to immobilize ensembles of 4.50 μm beads functionalized with HRP so as to generate high CL signals from capillary-driven chips.

Operation placement for application-specific digital microfluidic biochips

DEFF Research Database (Denmark)

Alistar, Mirela; Pop, Paul; Madsen, Jan

2013-01-01

Microfluidic-based biochips are replacing the conventional biochemical analyzers, and are able to integrate onchip all the necessary functions for biochemical analysis using microfluidics. The digital microfluidic biochips are based on the manipulation of liquids not as a continuous flow......, but as discrete droplets on an array of electrodes. Microfluidic operations, such as transport, mixing, split, are performed on this array by routing the corresponding droplets on a series of electrodes. Researchers have proposed several approaches for the synthesis of digital microfluidic biochips. All previous...

Evaluation of Ablation rate by the change of Sacrificial Material for PECS in EU-APR

International Nuclear Information System (INIS)

Hwang, Do Hyun; Kim, Yong Soo; Lee, Keun Sung

2015-01-01

EU-APR, modified and improved from its original design of APR1400, has been developed to comply with European Utility Requirements (EUR) and nuclear design requirements of the European countries. In EU-APR, Severe Accident Mitigation Systems are dedicated to providing an independent defense line from that of Engineered Safety Feature (ESF) and Diverse Safety Feature (DSF). They consist of Emergency Reactor Depressurization System (ERDS), Passive Ex-vessel corium retaining and Cooling System (PECS), Severe Accident Containment Spray System (SACSS), Hydrogen Mitigation System (HMS) and Containment Filtered Vent System (CFVS). The PECS, so called core catcher, was introduced to prevent the Molten Core Concrete Interaction (MCCI) after Reactor Vessel (RV) failure. The PECS has experienced a lot of changes from its original design. Recently, the most significant change was that as a SM, limestone concrete is installed on PECS's body wall instead of previous sacrificial material rich in Fe 2 O 3 . The main reason of this design change is to overcome the issue that the sacrificial material is ablated rather too fast when reacting with corium that contains a large fraction of Zr metal. Other changes in the geometry of PECS's wall and downcomer design are considered as minor ones. In this paper, the comparison of ablation rates between previous SM and limestone concrete is carried out using MAAP5 code with respective MCCI model according to the material. In this paper, major improvements of MAAP5 model for PECS in EU-APR are presented and the evaluation of ablation rate for the previous SM model and the new LC model is carried out by means of ablation depths with LBLOCA sequence. Two models have respective unique ablation process. The ablation of LC model proceeds at a constant rate regardless of water while the ablation of SM model proceeds at a faster rate before the arrival of cooling water for corium and SM mixture. The change of sacrificial material also

Open-source, community-driven microfluidics with Metafluidics.

Science.gov (United States)

Kong, David S; Thorsen, Todd A; Babb, Jonathan; Wick, Scott T; Gam, Jeremy J; Weiss, Ron; Carr, Peter A

2017-06-07

Microfluidic devices have the potential to automate and miniaturize biological experiments, but open-source sharing of device designs has lagged behind sharing of other resources such as software. Synthetic biologists have used microfluidics for DNA assembly, cell-free expression, and cell culture, but a combination of expense, device complexity, and reliance on custom set-ups hampers their widespread adoption. We present Metafluidics, an open-source, community-driven repository that hosts digital design files, assembly specifications, and open-source software to enable users to build, configure, and operate a microfluidic device. We use Metafluidics to share designs and fabrication instructions for both a microfluidic ring-mixer device and a 32-channel tabletop microfluidic controller. This device and controller are applied to build genetic circuits using standard DNA assembly methods including ligation, Gateway, Gibson, and Golden Gate. Metafluidics is intended to enable a broad community of engineers, DIY enthusiasts, and other nontraditional participants with limited fabrication skills to contribute to microfluidic research.

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

DEFF Research Database (Denmark)

Pfreundt, Andrea; Andersen, Karsten Brandt; Dimaki, Maria

2015-01-01

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...... 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....

‘Utilitarian’ judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good

Science.gov (United States)

Kahane, Guy; Everett, Jim A.C.; Earp, Brian D.; Farias, Miguel; Savulescu, Julian

2015-01-01

A growing body of research has focused on so-called ‘utilitarian’ judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such ‘utilitarian’ judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between ‘utilitarian’ judgment in such sacrificial dilemmas and a range of traits, attitudes, judgments and behaviors that either reflect or reject an impartial concern for the greater good of all. In Study 1, we found that rates of ‘utilitarian’ judgment were associated with a broadly immoral outlook concerning clear ethical transgressions in a business context, as well as with sub-clinical psychopathy. In Study 2, we found that ‘utilitarian’ judgment was associated with greater endorsement of rational egoism, less donation of money to a charity, and less identification with the whole of humanity, a core feature of classical utilitarianism. In Studies 3 and 4, we found no association between ‘utilitarian’ judgments in sacrificial dilemmas and characteristic utilitarian judgments relating to assistance to distant people in need, self-sacrifice and impartiality, even when the utilitarian justification for these judgments was made explicit and unequivocal. This lack of association remained even when we controlled for the antisocial element in ‘utilitarian’ judgment. Taken together, these results suggest that there is very little relation between sacrificial judgments in the hypothetical dilemmas that dominate current research, and a genuine utilitarian approach to ethics. PMID:25460392

Microfluidics on liquid handling stations (μF-on-LHS): an industry compatible chip interface between microfluidics and automated liquid handling stations.

Science.gov (United States)

Waldbaur, Ansgar; Kittelmann, Jörg; Radtke, Carsten P; Hubbuch, Jürgen; Rapp, Bastian E

2013-06-21

We describe a generic microfluidic interface design that allows the connection of microfluidic chips to established industrial liquid handling stations (LHS). A molding tool has been designed that allows fabrication of low-cost disposable polydimethylsiloxane (PDMS) chips with interfaces that provide convenient and reversible connection of the microfluidic chip to industrial LHS. The concept allows complete freedom of design for the microfluidic chip itself. In this setup all peripheral fluidic components (such as valves and pumps) usually required for microfluidic experiments are provided by the LHS. Experiments (including readout) can be carried out fully automated using the hardware and software provided by LHS manufacturer. Our approach uses a chip interface that is compatible with widely used and industrially established LHS which is a significant advancement towards near-industrial experimental design in microfluidics and will greatly facilitate the acceptance and translation of microfluidics technology in industry.

A microfluidic timer for timed valving and pumping in centrifugal microfluidics.

Science.gov (United States)

Schwemmer, F; Zehnle, S; Mark, D; von Stetten, F; Zengerle, R; Paust, N

2015-03-21

Accurate timing of microfluidic operations is essential for the automation of complex laboratory workflows, in particular for the supply of sample and reagents. Here we present a new unit operation for timed valving and pumping in centrifugal microfluidics. It is based on temporary storage of pneumatic energy and time delayed sudden release of said energy. The timer is loaded at a relatively higher spinning frequency. The countdown is started by reducing to a relatively lower release frequency, at which the timer is released after a pre-defined delay time. We demonstrate timing for 1) the sequential release of 4 liquids at times of 2.7 s ± 0.2 s, 14.0 s ± 0.5 s, 43.4 s ± 1.0 s and 133.8 s ± 2.3 s, 2) timed valving of typical assay reagents (contact angles 36-78°, viscosities 0.9-5.6 mPa s) and 3) on demand valving of liquids from 4 inlet chambers in any user defined sequence controlled by the spinning protocol. The microfluidic timer is compatible to all wetting properties and viscosities of common assay reagents and does neither require assistive equipment, nor coatings. It can be monolithically integrated into a microfluidic test carrier and is compatible to scalable fabrication technologies such as thermoforming or injection molding.

Electric Characterization and Modeling of Microfluidic-Based Dye-Sensitized Solar Cell

Directory of Open Access Journals (Sweden)

Adriano Sacco

2012-01-01

Full Text Available The electric response to an external periodic voltage of small amplitude of dye-sensitized solar cells (DSCs made up with an alternative architecture has been investigated. DSCs have been fabricated with a reversible sealing structure, based on microfluidic concepts, with a precise control on the geometric parameters of the active chamber. Cells with different electrolyte thicknesses have been characterized, without varying the thickness of the TiO2 layer, both under illumination and in dark conditions. Measurements of the electric impedance have been performed in the presence of an external bias ranging from 0 V to 0.8 V. The experimental data have been analyzed in terms of a transmission line model, with two transport channels. The results show that the photovoltaic performances of the microfluidic cell are comparable with those obtained in irreversibly sealed structures, actually demonstrating the reliability of the proposed device.

Materials for Microfluidic Immunoassays: A Review.

Science.gov (United States)

Mou, Lei; Jiang, Xingyu

2017-08-01

Conventional immunoassays suffer from at least one of these following limitations: long processing time, high costs, poor user-friendliness, technical complexity, poor sensitivity and specificity. Microfluidics, a technology characterized by the engineered manipulation of fluids in channels with characteristic lengthscale of tens of micrometers, has shown considerable promise for improving immunoassays that could overcome these limitations in medical diagnostics and biology research. The combination of microfluidics and immunoassay can detect biomarkers with faster assay time, reduced volumes of reagents, lower power requirements, and higher levels of integration and automation compared to traditional approaches. This review focuses on the materials-related aspects of the recent advances in microfluidics-based immunoassays for point-of-care (POC) diagnostics of biomarkers. We compare the materials for microfluidic chips fabrication in five aspects: fabrication, integration, function, modification and cost, and describe their advantages and drawbacks. In addition, we review materials for modifying antibodies to improve the performance of the reaction of immunoassay. We also review the state of the art in microfluidic immunoassays POC platforms, from the laboratory to routine clinical practice, and also commercial products in the market. Finally, we discuss the current challenges and future developments in microfluidic immunoassays. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microfluidic Arrayed Lab-On-A-Chip for Electrochemical Capacitive Detection of DNA Hybridization Events.

Science.gov (United States)

Ben-Yoav, Hadar; Dykstra, Peter H; Bentley, William E; Ghodssi, Reza

2017-01-01

A microfluidic electrochemical lab-on-a-chip (LOC) device for DNA hybridization detection has been developed. The device comprises a 3 × 3 array of microelectrodes integrated with a dual layer microfluidic valved manipulation system that provides controlled and automated capabilities for high throughput analysis of microliter volume samples. The surface of the microelectrodes is functionalized with single-stranded DNA (ssDNA) probes which enable specific detection of complementary ssDNA targets. These targets are detected by a capacitive technique which measures dielectric variation at the microelectrode-electrolyte interface due to DNA hybridization events. A quantitative analysis of the hybridization events is carried out based on a sensing modeling that includes detailed analysis of energy storage and dissipation components. By calculating these components during hybridization events the device is able to demonstrate specific and dose response sensing characteristics. The developed microfluidic LOC for DNA hybridization detection offers a technology for real-time and label-free assessment of genetic markers outside of laboratory settings, such as at the point-of-care or in-field environmental monitoring.

Microfluidic DNA microarrays in PMMA chips: streamlined fabrication via simultaneous DNA immobilization and bonding activation by brief UV exposure

DEFF Research Database (Denmark)

Sabourin, David; Petersen, J; Snakenborg, Detlef

2010-01-01

This report presents and describes a simple and scalable method for producing functional DNA microarrays within enclosed polymeric, PMMA, microfluidic devices. Brief (30 s) exposure to UV simultaneously immobilized poly(T)poly(C)-tagged DNA probes to the surface of unmodified PMMA and activated...... the surface for bonding below the glass transition temperature of the bulk PMMA. Functionality and validation of the enclosed PMMA microarrays was demonstrated as 18 patients were correctly genotyped for all eight mutation sites in the HBB gene interrogated. The fabrication process therefore produced probes...... with desired hybridization properties and sufficient bonding between PMMA layers to allow construction of microfluidic devices. The streamlined fabrication method is suited to the production of low-cost microfluidic microarray-based diagnostic devices and, as such, is equally applicable to the development...

A modular microfluidic architecture for integrated biochemical analysis.

Science.gov (United States)

Shaikh, Kashan A; Ryu, Kee Suk; Goluch, Edgar D; Nam, Jwa-Min; Liu, Juewen; Thaxton, C Shad; Chiesl, Thomas N; Barron, Annelise E; Lu, Yi; Mirkin, Chad A; Liu, Chang

2005-07-12

Microfluidic laboratory-on-a-chip (LOC) systems based on a modular architecture are presented. The architecture is conceptualized on two levels: a single-chip level and a multiple-chip module (MCM) system level. At the individual chip level, a multilayer approach segregates components belonging to two fundamental categories: passive fluidic components (channels and reaction chambers) and active electromechanical control structures (sensors and actuators). This distinction is explicitly made to simplify the development process and minimize cost. Components belonging to these two categories are built separately on different physical layers and can communicate fluidically via cross-layer interconnects. The chip that hosts the electromechanical control structures is called the microfluidic breadboard (FBB). A single LOC module is constructed by attaching a chip comprised of a custom arrangement of fluid routing channels and reactors (passive chip) to the FBB. Many different LOC functions can be achieved by using different passive chips on an FBB with a standard resource configuration. Multiple modules can be interconnected to form a larger LOC system (MCM level). We demonstrated the utility of this architecture by developing systems for two separate biochemical applications: one for detection of protein markers of cancer and another for detection of metal ions. In the first case, free prostate-specific antigen was detected at 500 aM concentration by using a nanoparticle-based bio-bar-code protocol on a parallel MCM system. In the second case, we used a DNAzyme-based biosensor to identify the presence of Pb(2+) (lead) at a sensitivity of 500 nM in <1 nl of solution.

Manipulation of microfluidic droplets by electrorheological fluid

KAUST Repository

Zhang, Menying

2009-09-01

Microfluidics, especially droplet microfluidics, attracts more and more researchers from diverse fields, because it requires fewer materials and less time, produces less waste and has the potential of highly integrated and computer-controlled reaction processes for chemistry and biology. Electrorheological fluid, especially giant electrorheological fluid (GERF), which is considered as a kind of smart material, has been applied to the microfluidic systems to achieve active and precise control of fluid by electrical signal. In this review article, we will introduce recent results of microfluidic droplet manipulation, GERF and some pertinent achievements by introducing GERF into microfluidic system: digital generation, manipulation of "smart droplets" and droplet manipulation by GERF. Once it is combined with real-time detection, integrated chip with multiple functions can be realized. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.

Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

Science.gov (United States)

Tait, Zachary S; Thompson, Megan; Stubbins, Aron

2015-07-01

The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Rapid mask prototyping for microfluidics.

Science.gov (United States)

Maisonneuve, B G C; Honegger, T; Cordeiro, J; Lecarme, O; Thiry, T; Fuard, D; Berton, K; Picard, E; Zelsmann, M; Peyrade, D

2016-03-01

With the rise of microfluidics for the past decade, there has come an ever more pressing need for a low-cost and rapid prototyping technology, especially for research and education purposes. In this article, we report a rapid prototyping process of chromed masks for various microfluidic applications. The process takes place out of a clean room, uses a commercially available video-projector, and can be completed in less than half an hour. We quantify the ranges of fields of view and of resolutions accessible through this video-projection system and report the fabrication of critical microfluidic components (junctions, straight channels, and curved channels). To exemplify the process, three common devices are produced using this method: a droplet generation device, a gradient generation device, and a neuro-engineering oriented device. The neuro-engineering oriented device is a compartmentalized microfluidic chip, and therefore, required the production and the precise alignment of two different masks.

Microfluidic Lab-on-a-Chip Platforms: Requirements, Characteristics and Applications

Science.gov (United States)

Mark, D.; Haeberle, S.; Roth, G.; von Stetten, F.; Zengerle, R.

This review summarizes recent developments in microfluidic platform approaches. In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the implementation of different application-specific (bio-) chemical processes, automated by microfluidic process integration [1]. A brief introduction into technical advances, major market segments and promising applications is followed by a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electro-kinetics, electrowetting, surface acoustic waves, and systems for massively parallel analysis. The review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposable, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols.

Integrated lenses in polystyrene microfluidic devices

KAUST Repository

Fan, Yiqiang; Li, Huawei; Foulds, Ian G.

2013-01-01

This paper reports a new method for integrating microlenses into microfluidic devices for improved observation. Two demonstration microfluidic devices were provided which were fabricated using this new technique. The integrated microlenses were

PREFACE: Nano- and microfluidics Nano- and microfluidics

Science.gov (United States)

Jacobs, Karin

2011-05-01

microchannels of oscillating width S Braunmüller, L Schmid and T Franke Semiflexible polymer conformation, distribution and migration in microcapillary flows Raghunath Chelakkot, Roland G Winkler and Gerhard Gompper Numerical simulation of tethered DNA in shear flow S Litvinov, X Y Hu and N A Adams Analysis of the fluctuations of a single-tethered, quantum-dot labeled DNA molecule in shear flow K Laube, K Günther and M Mertig Interaction of flexible surface hairs with near-wall turbulence Ch Brücker Development of a shear stress sensor to analyse the influence of polymers on the turbulent wall shear stress Bernardo Nottebrock, Sebastian Große and Wolfgang Schröder Small-scale particle advection, manipulation and mixing: beyond the hydrodynamic scale Arthur V Straube Microfluidic emulsion separation—simultaneous separation and sensing by multilayer nanofilm structures P Uhlmann, F Varnik, P Truman, G Zikos, J-F Moulin, P Müller-Buschbaum and M Stamm Filtration at the microfluidic level: enrichment of nanoparticles by tunable filters M Boettcher, S Schmidt, A Latz, M S Jaeger, M Stuke and C Duschl Nanoscale structures and dynamics of a boundary liquid layer M Walz, S Gerth, P Falus, M Klimczak, T H Metzger and A Magerl

Microfabrication and Applications of Opto-Microfluidic Sensors

Science.gov (United States)

Zhang, Daiying; Men, Liqiu; Chen, Qiying

2011-01-01

A review of research activities on opto-microfluidic sensors carried out by the research groups in Canada is presented. After a brief introduction of this exciting research field, detailed discussion is focused on different techniques for the fabrication of opto-microfluidic sensors, and various applications of these devices for bioanalysis, chemical detection, and optical measurement. Our current research on femtosecond laser microfabrication of optofluidic devices is introduced and some experimental results are elaborated. The research on opto-microfluidics provides highly sensitive opto-microfluidic sensors for practical applications with significant advantages of portability, efficiency, sensitivity, versatility, and low cost. PMID:22163904

Microfluidic cell culture systems for drug research.

Science.gov (United States)

Wu, Min-Hsien; Huang, Song-Bin; Lee, Gwo-Bin

2010-04-21

In pharmaceutical research, an adequate cell-based assay scheme to efficiently screen and to validate potential drug candidates in the initial stage of drug discovery is crucial. In order to better predict the clinical response to drug compounds, a cell culture model that is faithful to in vivo behavior is required. With the recent advances in microfluidic technology, the utilization of a microfluidic-based cell culture has several advantages, making it a promising alternative to the conventional cell culture methods. This review starts with a comprehensive discussion on the general process for drug discovery and development, the role of cell culture in drug research, and the characteristics of the cell culture formats commonly used in current microfluidic-based, cell-culture practices. Due to the significant differences in several physical phenomena between microscale and macroscale devices, microfluidic technology provides unique functionality, which is not previously possible by using traditional techniques. In a subsequent section, the niches for using microfluidic-based cell culture systems for drug research are discussed. Moreover, some critical issues such as cell immobilization, medium pumping or gradient generation in microfluidic-based, cell-culture systems are also reviewed. Finally, some practical applications of microfluidic-based, cell-culture systems in drug research particularly those pertaining to drug toxicity testing and those with a high-throughput capability are highlighted.

Nanostructures for all-polymer microfluidic systems

DEFF Research Database (Denmark)

Matschuk, Maria; Bruus, Henrik; Larsen, Niels Bent

2010-01-01

antistiction coating was found to improve the replication fidelity (shape and depth) of nanoscale features substantially. Arrays of holes of 50 nm diameter/35 nm depth and 100 nm/100 nm diameter, respectively, were mass-produced in cyclic olefin copolymer (Topas 5013) by injection molding. Polymer microfluidic...... channel chip parts resulted from a separate injection molding process. The microfluidic chip part and the nanostructured chip part were successfully bonded to form a sealed microfluidic system using air plasma assisted thermal bonding....

Microfluidic standardization: Past, present and future

NARCIS (Netherlands)

Heeren, H. van; Atkins, T.; Blom, M.; Bullema, J.E.; Tantra, R.; Verhoeven, D.; Verplanck, N.

2016-01-01

This paper addresses the issue of standardization in microfluidics. It contains the main points of an industry wide agreement about microfluidic port pitches and port nomenclature. It also addresses device classification and future steps.

Detection of Ca2+-induced acetylcholine released from leukemic T-cells using an amperometric microfluidic sensor.

Science.gov (United States)

Akhtar, Mahmood H; Hussain, Khalil K; Gurudatt, N G; Shim, Yoon-Bo

2017-12-15

A microfluidic structured-dual electrodes sensor comprising of a pair of screen printed carbon electrodes was fabricated to detect acetylcholine, where one of them was used for an enzyme reaction and another for a detection electrode. The former was coated with gold nanoparticles and the latter with a porous gold layer, followed by electropolymerization of 2, 2:5,2-terthiophene-3-(p-benzoic acid) (pTTBA) on both the electrodes. Then, acetylcholinesterase was covalently attached onto the reaction electrode, and hydrazine and choline oxidase were co-immobilized on the detection electrode. The layers of both modified electrodes were characterized employing voltammetry, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and quartz crystal microscopy. After the modifications of both electrode surfaces, they were precisely faced each other to form a microfluidic channel structure, where H 2 O 2 produced from the sequential enzymatic reactions was reduced by hydrazine to obtain the analytical signal which was analyzed by the detection electrode. The microfluidic sensor at the optimized experimental conditions exhibited a wide dynamic range from 0.7nM to 1500μM with the detection limit of 0.6 ± 0.1nM based on 3s (S/N = 3). The biomedical application of the proposed sensor was evaluated by detecting acetylcholine in human plasma samples. Moreover, the Ca 2+ -induced acetylcholine released in leukemic T-cells was also investigated to show the in vitro detection ability of the designed microfluidic sensor. Interference due to the real component matrix were also studied and long term stability of the designed sensor was evaluated. The analytical performance of the designed sensor was also compared with commercially available ACh detection kit. Copyright © 2017 Elsevier B.V. All rights reserved.

Droplet based microfluidics

International Nuclear Information System (INIS)

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

2012-01-01

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

Fabrication of scalable and structured tissue engineering scaffolds using water dissolvable sacrificial 3D printed moulds

DEFF Research Database (Denmark)

Mohanty, Soumyaranjan; Larsen, Layla Bashir; Trifol Guzman, Jon

2015-01-01

One of the major challenges in producing large scale engineered tissue is the lack of ability to create large highly perfused scaffolds in which cells can grow at a high cell density and viability. Here, we explore 3D printed polyvinyl alcohol (PVA) as a sacrificial mould in a polymer casting...

Evaluation of Ablation rate by the change of Sacrificial Material for PECS in EU-APR

Energy Technology Data Exchange (ETDEWEB)

Hwang, Do Hyun; Kim, Yong Soo; Lee, Keun Sung [KHNP-CRI, Daejeon (Korea, Republic of)

2015-05-15

EU-APR, modified and improved from its original design of APR1400, has been developed to comply with European Utility Requirements (EUR) and nuclear design requirements of the European countries. In EU-APR, Severe Accident Mitigation Systems are dedicated to providing an independent defense line from that of Engineered Safety Feature (ESF) and Diverse Safety Feature (DSF). They consist of Emergency Reactor Depressurization System (ERDS), Passive Ex-vessel corium retaining and Cooling System (PECS), Severe Accident Containment Spray System (SACSS), Hydrogen Mitigation System (HMS) and Containment Filtered Vent System (CFVS). The PECS, so called core catcher, was introduced to prevent the Molten Core Concrete Interaction (MCCI) after Reactor Vessel (RV) failure. The PECS has experienced a lot of changes from its original design. Recently, the most significant change was that as a SM, limestone concrete is installed on PECS's body wall instead of previous sacrificial material rich in Fe{sub 2}O{sub 3}. The main reason of this design change is to overcome the issue that the sacrificial material is ablated rather too fast when reacting with corium that contains a large fraction of Zr metal. Other changes in the geometry of PECS's wall and downcomer design are considered as minor ones. In this paper, the comparison of ablation rates between previous SM and limestone concrete is carried out using MAAP5 code with respective MCCI model according to the material. In this paper, major improvements of MAAP5 model for PECS in EU-APR are presented and the evaluation of ablation rate for the previous SM model and the new LC model is carried out by means of ablation depths with LBLOCA sequence. Two models have respective unique ablation process. The ablation of LC model proceeds at a constant rate regardless of water while the ablation of SM model proceeds at a faster rate before the arrival of cooling water for corium and SM mixture. The change of sacrificial material

It's immoral, but I'd do it! Psychopathy traits affect decision-making in sacrificial dilemmas and in everyday moral situations.

Science.gov (United States)

Pletti, Carolina; Lotto, Lorella; Buodo, Giulia; Sarlo, Michela

2017-05-01

This research investigated whether emotional hyporeactivity affects moral judgements and choices of action in sacrificial moral dilemmas and in everyday moral conflict situations in which harm to other's welfare is differentially involved. Twenty-six participants with high trait psychopathy (HP) and 25 with low trait psychopathy (LP) were selected based on the primary psychopathy scale of the Levenson Self-Report Psychopathy Scale. HP participants were more likely to sacrifice one person to save others in sacrificial dilemmas and to pursue a personal advantage in everyday moral situations entailing harm to another's good. While deciding in these situations, HP participants experienced lower unpleasantness as compared to LP participants. Conversely, no group differences emerged in choice of action and unpleasantness ratings for everyday moral situations that did not entail harm to others. Importantly, moral judgements did not differ in the two groups. These results suggest that high psychopathy trait affects choices of action in sacrificial dilemmas because of reduced emotional reactivity to harmful acts. The dissociation between choice of action and moral judgement suggests that the former is more closely related to emotional experience. Also, emotion seems to play a critical role in discriminating harmful from harmless acts and in driving decisions accordingly. © 2016 The British Psychological Society.

Polymer-based platform for microfluidic systems

Science.gov (United States)

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.

Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication.

Science.gov (United States)

Zhang, Min; Li, Songjing

2016-01-01

In this work, liquid colour-changing lenses for vision protection, camouflage and optical filtering are developed by circulating colour liquids through microfluidic channels on the lenses manually. Soft lithography technology is applied to fabricate the silicone liquid colour-changing layers with microfluidic channels on the lenses instead of mechanical machining. To increase the hardness and abrasion resistance of the silicone colour-changing layers on the lenses, proper fabrication parameters such as 6:1 (mass ration) mixing proportion and 100 °C curing temperature for 2 h are approved for better soft lithography process of the lenses. Meanwhile, a new surface treatment for the irreversible bonding of silicone colour-changing layer with optical resin (CR39) substrate lens by using 5 % (volume ratio) 3-Aminopropyltriethoxysilane solution is proposed. Vision protection, camouflage and optical filtering functions of the lenses are investigated with different designs of the channels and multi-layer structures. Each application can not only well achieve their functional demands, but also shows the advantages of functional flexibility, rapid prototyping and good controllability compared with traditional ways. Besides optometry, some other designs and applications of the lenses are proposed for potential utility in the future.

Tuning 3D topography on biomimetic surface for efficient self-cleaning and microfluidic manipulation

International Nuclear Information System (INIS)

Guan, Wei-Sheng; Huang, Han-Xiong; Chen, An-Fu

2015-01-01

Currently, micro-/nanotopography on polymeric replica is generally limited to 2D when a mechanical demolding approach is applied. In this work, one-step replication of bio-inspired 3D topography is achieved using microinjection compression molding with novel dual-layer molds. Using a proposed flexible template, the replica topography and wettability are highly tunable during molding. Moreover, dual-scale topography on the mold is developed by coating the micropatterned insert with submicron silica particles. Contact angle and roll-off angle measurements indicate the lotus leaf, rose petal and rice leaf effects on biomimetic surfaces. Among the three kinds of surfaces, the petal-inspired surface possesses the superior performance in self-cleaning submicron contaminants and mechanical robustness, which is highly correlated to the low roughness-induced adhesive superhydrophobicity and the absence of fragile submicron-/nanostructure, respectively. Furthermore, a multi-layer mold structure is proposed for fabricating the open microfluidic devices. The embedment of the hydrophilic and hydrophobic silica particles in the microstructured open channel and the hydrophobic silica particles in the background area during replication renders the wettability contrast sharp, realizing the self-driven flow of microfluid confined within the open microchannel. (paper)

Tuning 3D topography on biomimetic surface for efficient self-cleaning and microfluidic manipulation

Science.gov (United States)

Guan, Wei-Sheng; Huang, Han-Xiong; Chen, An-Fu

2015-03-01

Currently, micro-/nanotopography on polymeric replica is generally limited to 2D when a mechanical demolding approach is applied. In this work, one-step replication of bio-inspired 3D topography is achieved using microinjection compression molding with novel dual-layer molds. Using a proposed flexible template, the replica topography and wettability are highly tunable during molding. Moreover, dual-scale topography on the mold is developed by coating the micropatterned insert with submicron silica particles. Contact angle and roll-off angle measurements indicate the lotus leaf, rose petal and rice leaf effects on biomimetic surfaces. Among the three kinds of surfaces, the petal-inspired surface possesses the superior performance in self-cleaning submicron contaminants and mechanical robustness, which is highly correlated to the low roughness-induced adhesive superhydrophobicity and the absence of fragile submicron-/nanostructure, respectively. Furthermore, a multi-layer mold structure is proposed for fabricating the open microfluidic devices. The embedment of the hydrophilic and hydrophobic silica particles in the microstructured open channel and the hydrophobic silica particles in the background area during replication renders the wettability contrast sharp, realizing the self-driven flow of microfluid confined within the open microchannel.

In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method.

Science.gov (United States)

Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

2015-09-01

In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). Copyright © 2015 Elsevier B.V. All rights reserved.

Fluorimetric urease inhibition assay on a multilayer microfluidic chip with immunoaffinity immobilized enzyme reactors.

Science.gov (United States)

Zhang, Qin; Tang, Xiuwen; Hou, Fenghua; Yang, Jianping; Xie, Zhiyong; Cheng, Zhiyi

2013-10-01

We fabricated a three-layer polydimethylsiloxane (PDMS)-based microfluidic chip for realizing urease inhibition assay with sensitive fluorescence detection. Procedures such as sample prehandling, enzyme reaction, reagent mixing, fluorescence derivatization, and detection can be readily carried out. Urease reactors were prepared by adsorption of rabbit immunoglobulin G (IgG) and immunoreaction with urease-conjugated goat anti-rabbit IgG. Acetohydroxamic acid (AHA) as a competitive inhibitor of urease was tested on the chip. Microfluidically generated gradient concentrations of AHA with substrate (urea) were loaded into urease reactors. After incubation, the produced ammonia was transported out of reactors and then reacted with o-phthalaldehyde (OPA) to generate fluorescent products. Urease inhibition was indicated by a decrease in fluorescence signal detected by microplate reader. The IC50 value of AHA was determined and showed good agreement with that obtained in microplate. The presented device combines several steps of the analytical process with advantages of low reagent consumption, reduced analysis time, and ease of manipulation. This microfluidic approach can be extended to the screening of inhibitory compounds in drug discovery. Copyright © 2013 Elsevier Inc. All rights reserved.

Fabricating and Characterizing the Microfluidic Solid Phase Extraction Module Coupling with Integrated ESI Emitters

Directory of Open Access Journals (Sweden)

Hangbin Tang

2018-05-01

Full Text Available Microfluidic chips coupling with mass spectrometry (MS will be of great significance to the development of relevant instruments involving chemical and bio-chemical analysis, drug detection, food and environmental applications and so on. In our previous works, we proposed two types of microfluidic electrospray ionization (ESI chip coupling with MS: the two-phase flow focusing (FF ESI microfluidic chip and the corner-integrated ESI emitter, respectively. However the pretreatment module integrated with these ESI emitters is still a challenging problem. In this paper, we concentrated on integrating the solid phase micro-extraction (SPME module with our previous proposed on-chip ESI emitters; the fabrication processes of such SPME module are fully compatible with our previous proposed ESI emitters based on the multi-layer soft lithography. We optimized the structure of the integrated chip and characterized its performance using standard samples. Furthermore, we verified its abilities of salt removal, extraction of multiple analytes and separation through on-chip elution using mimic biological urine spiked with different drugs. The results indicated that our proposed integrated module with ESI emitters is practical and effective for real biological sample pretreatment and MS detection.

Phenomena in the interaction among a core melt and protective and sacrificial materials

International Nuclear Information System (INIS)

Steinwarz, W.; Koller, W.; Dyllong, N.; Fischer, M.; Hellmann, S.; Lansmann, V.; Nie, M.; Haefner, W.; Alkan, Z.; Andrae, P.; Rensing, B.

2000-01-01

In a postulated core meltdown accident in a light water reactor there are bound to be interactions, in the ex-vessel phase, among the core melt and the structural materials within and below the reactor cavity. In existing plants, these structural materials normally are structural concrete, while future, evolutionary reactor lines are to have sacrificial and protective materials specially designed for this hypothetical case. To add to the state of knowledge about the phenomena occurring, experiments need to be conducted under conditions as realistic as possible. Within the research programs funded by the European Union, the German Federal Ministry for Economics, and the German nuclear power plant operators, experiments on a laboratory as well as an industrial scale on these problems are being carried out in the two projects called CORESA (COrium on REfractory and SAcrificial materials) and ECOSTAR (Ex-vessel COre melt STAbilization Research). The experiments are accompanied by an extensive analytical theoretical program also serving to advance and validate computer codes on the problems under investigation. The projects, which are carried out with international European participation, are expected to allow a concept to be developed for managing postulated accident scenarios involving core meltdown for innovative nuclear power plants, and to provide findings on risk evaluation of plants now in operation so as to further develop accident management measures. (orig.) [de

Development of microfluidic cell culture devices towards an in vitro human intestinal barrier model

DEFF Research Database (Denmark)

Tan, Hsih-Yin

to enable real-time detection of cell responses, adjustment of cellular stimulation etc. leading to establishment of conditional experiments. In this project, microfluidic systems engineering was leveraged to develop an eight chamber multi-layer microchip for intestinal barrier studies. Sandwiched between...... the layers was a modified Teflon porous membrane for cell culture. The novelty lies in modifying the surface of the porous Teflon support membrane using thiol-ene ‘click’ chemistry, thus allowing the modified Teflon membrane to be bonded between the chip layers to form an enclosed microchip. Successful...... application of the multi-layer microchip was demonstrated by integrating the microchip to an existing cell culture fluidic system to culture the human intestinal epithelial cells, Caco-2, for long term studies. Under the continuous low flow conditions, the cells differentiated into columnar cells displaying...

Microfluidic process monitor for industrial solvent extraction system

Science.gov (United States)

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.

Integration of fractal biosensor in a digital microfluidic platform

KAUST Repository

Mashraei, Yousof

2015-11-01

Fractal capacitive electrodes have been successfully integrated into a digital microfluidic open-platform. These electrodes perform actuation and withstand voltages up to 300V without insulation-layer breakdown. They were used to quantify the concentration levels of C-reactive protein (CRP) to determine the risk of cardiovascular disease. The capacitance increased sevenfold and stabilized in less than 5 minutes. The sensor shows a decreasing trend of capacitance readouts with the increase of concentrations. The same immunoassay was tested with untreated electrodes and showed no significant response, which suggests that immobilization was necessary. This configuration allows the electrodes to be used as biosensors.

From a Philosophical point of view, can the Budism Be An Anti-Sacrificial Science?

Directory of Open Access Journals (Sweden)

Francisco Felizol Marques

2014-04-01

Full Text Available Both on Buddhist tradition and René Girard´s thought ignorance and desire are on the basis of suffering and violence. The Buddhist tradition puts/takes ignorance, that nothing exists in and by itself, avydia as the cause of all sufferings because it generates a chain of desire / aversion that leads us to an imprisonment where we move from desiring an object to another. Girard´s perspective founds violence´s origin on the ignorance of our mimetic desire. The subject ignores that, far from being free, autonomous and differentiated, as the "romantic lie" prays, he only desires and wants by imitating a model. Neither the subject nor the object, which the subject freely thinks to desire, exist free for themselves. While this model prevails, he will react more and more violently to the claims of the subject; and even if the subject overtakes its model, he will greedily seek another and another model, always doomed to deception. If we add to this the proximity of the two anti-sacrificial perspectives, displayed on the descriptive closeness of the samsara´s wheel and the circular and sacrificial time of a pagan society, we find between Girard and the buddhist tradition enough common points for their mutual understanding.

Laser patterning and welding of transparent polymers for microfluidic device fabrication

Science.gov (United States)

Pfleging, W.; Baldus, O.

2006-02-01

CO II-laser-assisted micro-patterning of polymethylmethacrylate (PMMA) or cyclo-olefin copolymer (COC) has a great potential for the rapid manufacturing of polymeric devices including cutting and structuring. Channel widths of about 50 μm as well as large area patterning of reservoir structures or drilling of vias are established. For this purpose a high quality laser beam is necessary as well as an appropriate beam forming system. In combination with laser transmission welding a fast fabrication of two- and three-dimensional micro-fluidic devices was possible. Welding as well as multilayer welding of transparent polymers was investigated for different polymers such as PMMA, polyvinylidene fluoride (PVDF), COC, and polystyrene (PS). The laser transmission welding process is performed with a high-power diode laser (wavelength 940 nm). An absorption layer with a thickness of several nanometers is deposited onto the polymer surfaces. The welding process has been established for the welding of polymeric parts containing microchannels, if the width of the channels is equal or larger than 100μm. For smaller feature sizes the absorption layer is structured by UV-laser radiation in order to get a highly localized welding seam, e.g., for the limitation of thermal penetration and thermal damaging of functional features such as channels, thin walls or temperature-sensitive substances often contained in micro-fluidic devices. This process strategy was investigated for the welding of capillary electrophoresis chips and capillary blood separation chips, including channel widths of 100 μm and 30 μm. Analysis of the thickness of the absorption layer was carried out with optical transmission spectroscopy.

Material Biocompatibility for PCR Microfluidic Chips

KAUST Repository

Kodzius, Rimantas

2010-04-23

As part of the current miniaturization trend, biological reactions and processes are being adapted to microfluidics devices. PCR is the primary method employed in DNA amplification, its miniaturization is central to efforts to develop portable devices for diagnostics and testing purposes. A problem is the PCR-inhibitory effect due to interaction between PCR reagents and the surrounding environment, which effect is increased in high-surface-are-to-volume ration microfluidics. In this study, we evaluated the biocompatibility of various common materials employed in the fabrication of microfluidic chips, including silicon, several kinds of silicon oxide, glasses, plastics, wax, and adhesives. Two-temperature PCR was performed with these materials to determine their PCR-inhibitory effect. In most of the cases, addition of bovine serum albumin effectively improved the reaction yield. We also studied the individual PCR components from the standpoint of adsorption. Most of the materials did not inhibit the DNA, whereas they did show noticeable interaction with the DNA polymerase. Our test, instead of using microfluidic devices, can be easily conducted in common PCR tubes using a standard bench thermocycler. Our data supports an overview of the means by which the materials most bio-friendly to microfluidics can be selected.

Material Biocompatibility for PCR Microfluidic Chips

KAUST Repository

Kodzius, Rimantas; Chang, Donald Choy; Gong, Xiuqing; Wen, Weijia; Wu, Jinbo; Xiao, Kang; Yi, Xin

2010-01-01

As part of the current miniaturization trend, biological reactions and processes are being adapted to microfluidics devices. PCR is the primary method employed in DNA amplification, its miniaturization is central to efforts to develop portable devices for diagnostics and testing purposes. A problem is the PCR-inhibitory effect due to interaction between PCR reagents and the surrounding environment, which effect is increased in high-surface-are-to-volume ration microfluidics. In this study, we evaluated the biocompatibility of various common materials employed in the fabrication of microfluidic chips, including silicon, several kinds of silicon oxide, glasses, plastics, wax, and adhesives. Two-temperature PCR was performed with these materials to determine their PCR-inhibitory effect. In most of the cases, addition of bovine serum albumin effectively improved the reaction yield. We also studied the individual PCR components from the standpoint of adsorption. Most of the materials did not inhibit the DNA, whereas they did show noticeable interaction with the DNA polymerase. Our test, instead of using microfluidic devices, can be easily conducted in common PCR tubes using a standard bench thermocycler. Our data supports an overview of the means by which the materials most bio-friendly to microfluidics can be selected.

TiO2 nanosheets synthesized by atomic layer deposition for photocatalysis

Directory of Open Access Journals (Sweden)

Riyanto Edy

2016-10-01

Full Text Available Two-dimensional TiO2 nanosheets were synthesized by atomic layer deposition (ALD on dissolvable sacrificial polymer layer. The photocatalytic performance of free-standing TiO2 nanosheets prepared with different numbers of ALD cycles (100, 300, 500, and 1000 were investigated by evaluating the degradation rates of methyl orange solutions. It is shown that the photocatalytic activity increases due to Ti3+ defect and the locally ordered structures in amorphous TiO2 nanosheets. The difference in the surface areas of nanosheets may also play a crucial role in the photocatalytic activity. The results obtained in this work can have potential applications in fields like water splitting and dye-sensitized solar cells.

Microfluidic Flame Barrier

Science.gov (United States)

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

2013-01-01

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

Routing-based synthesis of digital microfluidic biochips

DEFF Research Database (Denmark)

Maftei, Elena; Pop, Paul; Madsen, Jan

2012-01-01

Microfluidic biochips are replacing the conventional biochemical analyzers, and are able to integrate on-chip all the necessary functions for biochemical analysis. The “digital” biochips are manipulating liquids as discrete droplets on a two-dimensional array of electrodes. Basic microfluidic...... electrodes are considered occupied during the operation execution, although the droplet uses only one electrode at a time. Moreover, the operations can actually be performed by routing the droplets on any sequence of electrodes on the microfluidic array. Hence, in this paper, we eliminate the concept...... on the surface of the microfluidic array. We have extended the GRASP-based algorithm to consider contamination avoidance during routing-based synthesis. Several real-life examples and synthetic benchmarks are used to evaluate the proposed approaches....

Silver doped hydroxyapatite coatings by sacrificial anode deposition under magnetic field.

Science.gov (United States)

Swain, S; Rautray, T R

2017-09-13

Uniform distribution of silver (Ag) in the hydroxyapatite (HA) coated Ti surface has been a concern for which an attempt has been made to dope Ag in HA coating with and without magnetic field. Cathodic deposition technique was employed to coat Ag incorporated hydroxyapatite coating using a sacrificial silver anode method by using NdFeB bar magnets producing 12 Tesla magnetic field. While uniform deposition of Ag was observed in the coatings under magnetic field, dense coating was evident in the coating without magnetic field conditions. Uniformly distributed Ag incorporated HA in the present study has potential to fight microorganism while providing osseoconduction properties of the composite coating.

Controlling two-phase flow in microfluidic systems using electrowetting

NARCIS (Netherlands)

Gu, H.

2011-01-01

Electrowetting (EW)-based digital microfluidic systems (DMF) and droplet-based two-phase flow microfluidic systems (TPF) with closed channels are the most widely used microfluidic platforms. In general, these two approaches have been considered independently. However, integrating the two

Microfluidic technology for PET radiochemistry

International Nuclear Information System (INIS)

Gillies, J.M.; Prenant, C.; Chimon, G.N.; Smethurst, G.J.; Dekker, B.A.; Zweit, J.

2006-01-01

This paper describes the first application of a microfabricated reaction system to positron emission tomography (PET) radiochemistry. We have applied microfluidic technology to synthesise PET radiopharmaceuticals using 18 F and 124 I as labels for fluorodeoxyglucose (FDG) and Annexin-V, respectively. These reactions involved established methods of nucleophilic substitution on a mannose triflate precursor and direct iodination of the protein using iodogen as an oxidant. This has demonstrated a proof of principle of using microfluidic technology to radiochemical reactions involving low and high molecular weight compounds. Using microfluidic reactions, [ 18 F]FDG was synthesised with a 50% incorporation of the available F-18 radioactivity in a very short time of 4 s. The radiolabelling efficiency of 124 I Annexin-V was 40% after 1 min reaction time. Chromatographic analysis showed that such reaction yields are comparable to conventional methods, but in a much shorter time. The yields can be further improved with more optimisation of the microfluidic device itself and its fluid mixing profiles. This demonstrates the potential for this technology to have an impact on rapid and simpler radiopharmaceutical synthesis using short and medium half-life radionuclides

Preface book Microfluidics for medical applications

NARCIS (Netherlands)

van den Berg, Albert; Segerink, Loes Irene

2015-01-01

This book presents an overview of the major microfluidics techniques and platforms used for medicine and medical applications, providing the reader with an overview of the recent developments in this field. It is divided in three parts: (1) tissue and organs on-chip, (2) microfluidics for medicine

High content screening in microfluidic devices

Science.gov (United States)

Cheong, Raymond; Paliwal, Saurabh; Levchenko, Andre

2011-01-01

Importance of the field Miniaturization is key to advancing the state-of-the-art in high content screening (HCS), in order to enable dramatic cost savings through reduced usage of expensive biochemical reagents and to enable large-scale screening on primary cells. Microfluidic technology offers the potential to enable HCS to be performed with an unprecedented degree of miniaturization. Areas covered in this review This perspective highlights a real-world example from the authors’ work of HCS assays implemented in a highly miniaturized microfluidic format. Advantages of this technology are discussed, including cost savings, high throughput screening on primary cells, improved accuracy, the ability to study complex time-varying stimuli, and ease of automation, integration, and scaling. What the reader will gain The reader will understand the capabilities of a new microfluidics-based platform for HCS, and the advantages it provides over conventional plate-based HCS. Take home message Microfluidics technology will drive significant advancements and broader usage and applicability of HCS in drug discovery. PMID:21852997

Manipulation of microfluidic droplets by electrorheological fluid

KAUST Repository

Zhang, Menying; Gong, Xiuqing; Wen, Weijia

2009-01-01

Microfluidics, especially droplet microfluidics, attracts more and more researchers from diverse fields, because it requires fewer materials and less time, produces less waste and has the potential of highly integrated and computer

Reconfigurable microfluidic platform in ice

OpenAIRE

Varejka, M.

2008-01-01

Microfluidic devices are popular tools in the biotechnology industry where they provide smaller reagent requirements, high speed of analysis and the possibility for automation. The aim of the project is to make a flexible biocompatible microfluidic platform adapted to different specific applications, mainly analytical and separations which parameters and configuration can be changed multiple times by changing corresponding computer programme. The current project has been sup...

Microfluidic Devices in Advanced Caenorhabditis elegans Research

Directory of Open Access Journals (Sweden)

Muniesh Muthaiyan Shanmugam

2016-08-01

Full Text Available The study of model organisms is very important in view of their potential for application to human therapeutic uses. One such model organism is the nematode worm, Caenorhabditis elegans. As a nematode, C. elegans have ~65% similarity with human disease genes and, therefore, studies on C. elegans can be translated to human, as well as, C. elegans can be used in the study of different types of parasitic worms that infect other living organisms. In the past decade, many efforts have been undertaken to establish interdisciplinary research collaborations between biologists, physicists and engineers in order to develop microfluidic devices to study the biology of C. elegans. Microfluidic devices with the power to manipulate and detect bio-samples, regents or biomolecules in micro-scale environments can well fulfill the requirement to handle worms under proper laboratory conditions, thereby significantly increasing research productivity and knowledge. The recent development of different kinds of microfluidic devices with ultra-high throughput platforms has enabled researchers to carry out worm population studies. Microfluidic devices primarily comprises of chambers, channels and valves, wherein worms can be cultured, immobilized, imaged, etc. Microfluidic devices have been adapted to study various worm behaviors, including that deepen our understanding of neuromuscular connectivity and functions. This review will provide a clear account of the vital involvement of microfluidic devices in worm biology.

Multi-chamber and multi-layer thiol-ene microchip for cell culture

DEFF Research Database (Denmark)

Tan, H. Y.; Hemmingsen, Mette; Lafleur, Josiane P.

2014-01-01

We present a multi-layer and multi-chamber microfluidic chip fabricated using two different thiol-ene mixtures. Sandwiched between the thiol-ene chip layers is a commercially available membrane whose morphology has been altered with coatings of thiol-ene mixtures. Experiments have been conducted ...... with the microchip and shown that the fabricated microchip is suitable for long term cell culture....

Designer silica layers for advanced applications: Processing and properties

Science.gov (United States)

Anderson, Adam

Recently, as scientists have investigated the application of conventional MEMS devices to biological systems, the exciting fields of bio-MEMS and microfluidics have emerged. Due to their small size, bio-MEMS and microfluidics devices offer the advantage of requiring only small sample and reagent volumes, in a potentially low-cost, integrated package. Such devices have the potential to significantly advance point-of-care diagnostics devices and improve overall patient care. However, due to the extremely small feature size, the large surface area-to-volume ratio in these devices makes controlling surface interactions of critical importance. Recently, there has been a shift to polymeric materials for fabrication of microfluidics devices due to their lower cost, ease of device fabrication by various processes, varied and favorable material properties, and, in some cases, pre-existing regulatory agency approvals. As a result, various surface modification strategies for polymeric surfaces have been proposed, but with only limited success. The proven success of organosilicon-based precursors in a wide variety of surface modification strategies has been demonstrated, with a body of knowledge on the general subject dating back nearly fifty years. However, these proven methodologies cannot be transferred to many important polymeric materials due to a lack of sufficient reactive groups on the surface. If any polymer surface could be made reactive by some intermediate treatment, the wide body of knowledge of organosilicon-based surface modification chemistries could be leveraged to advance the state-of-the-art in surface modification for microfluidics applications, where polymeric substrates are commonly encountered. This thesis reports on the processing properties and chemical properties of a vapor deposited silica layer, which is formed from the vapor phase hydrolysis of silicon tetrachloride. This layer can be deposited at low temperatures to a wide variety of substrates

Microfluidic Technologies for Synthetic Biology

Directory of Open Access Journals (Sweden)

Sung Kuk Lee

2011-06-01

Full Text Available Microfluidic technologies have shown powerful abilities for reducing cost, time, and labor, and at the same time, for increasing accuracy, throughput, and performance in the analysis of biological and biochemical samples compared with the conventional, macroscale instruments. Synthetic biology is an emerging field of biology and has drawn much attraction due to its potential to create novel, functional biological parts and systems for special purposes. Since it is believed that the development of synthetic biology can be accelerated through the use of microfluidic technology, in this review work we focus our discussion on the latest microfluidic technologies that can provide unprecedented means in synthetic biology for dynamic profiling of gene expression/regulation with high resolution, highly sensitive on-chip and off-chip detection of metabolites, and whole-cell analysis.

In situ photo-immobilised pH gradient isoelectric focusing and zone electrophoresis integrated two-dimensional microfluidic chip electrophoresis for protein separation

International Nuclear Information System (INIS)

Lin, Fengmin; Yu, Shiyong; Gu, Le; Zhu, Xuetao; Wang, Jianshe; Zhu, Han; Lu, Yi; Wang, Yihua; Deng, Yulin; Geng, Lina

2015-01-01

A method is introduced for open-column photo-induced site-selective immobilization of pH gradients in a layer of PEG-methacrylate in a multi-dimensional microfluidic chip for use in electrophoresis. It has several attractive features: (a) mixtures of fluorescently labelled proteins carbonic anhydrase, catalase and myoglobin in their native state can be separated by pH-gradient isoelectric focusing (IEF) and zone electrophoresis (CZE) using integrated 2D chip electrophoresis; (b) compared to strip packing or monolithic photo-immobilization, it overcomes the shortcomings of free carrier ampholyte-based 2D chip electrophoresis in an easy way; (c) larger amount of sample can be loaded into the open column-mode electrophoresis (d) immobilized pH gradients can be re-used and the chip can be recycled; (e) a multilayer 3D pH gradient is established by a layer-by-layer assembly technique to further increase the separation capacity. In our perception, this strategy has a large potential in microfluidic chip-based separation schemes because of its simplicity, separation power, re-usability, and separation capacity. (author)

Design of Protein-Coated Carbon Nanotubes Loaded with Hydrophobic Drugs through Sacrificial Templating of Mesoporous Silica Shells.

Science.gov (United States)

Fiegel, Vincent; Harlepp, Sebastien; Begin-Colin, Sylvie; Begin, Dominique; Mertz, Damien

2018-03-26

One key challenge in the fields of nanomedicine and tissue engineering is the design of theranostic nanoplatforms able to monitor their therapeutic effect by imaging. Among current developed nano-objects, carbon nanotubes (CNTs) were found suitable to combine imaging, photothermal therapy, and to be loaded with hydrophobic drugs. However, a main problem is their resulting low hydrophilicity. To face this problem, an innovative method is developed here, which consists in loading the surface of carbon nanotubes (CNTs) with drugs followed by a protein coating around them. The originality of this method relies on first covering CNTs with a sacrificial template mesoporous silica (MS) shell grafted with isobutyramide (IBAM) binders on which a protein nanofilm is strongly adhered through IBAM-mediated physical cross-linking. This concept is first demonstrated without drugs, and is further improved with the suitable loading of hydrophobic drugs, curcumin (CUR) and camptothecin (CPT), which are retained between the CNTs and human serum albumin (HSA) layer. Such novel nanocomposites with favorable photothermal properties are very promising for theranostic systems, drug delivery, and phototherapy applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2015-06-11

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

In search of low cost biological analysis: Wax or acrylic glue bonded paper microfluidic devices

KAUST Repository

Kodzius, Rimantas

2011-01-22

In this body of work we have been developing and characterizing paper based microfluidic fabrication technologies to produce low cost biological analysis. Specifically we investigated the performance of paper microfluidics that had been bonded using wax or acrylic glue, and characterized the affect of these and other microfluidic materials on the polymerase chain reaction (PCR). We report a simple, low-cost and detachable microfluidic chip incorporating easily accessible paper, glass slides or other polymer films as the chip materials along with adhesive wax or cyanoacrylate-based resin as the recycling bonding material. We use a laser to cut through the paper or film to form patterns and then sandwich the paper and film between glass sheets or polymer membranes. The hot-melt adhesive wax or simple cyanoacrylate-based resin can realize bridge bonding between various materials, for example, paper, polymethylmethacrylate film, glass sheets, or metal plate. The wax bonding process is reversible and the wax is reusable through a melting and cooling process. With this process, a three-dimensional (3D) microfluidic chip is achievable by evacuating the channels of adhesive material in a hot-water. We applied the wax-paper based microfluidic chip to HeLa cell electroporation. Subsequently, a prototype of a 5-layer 3D chip was fabricated by multilayer wax bonding. To check the sealing ability and the durability of the chip, green fluorescence protein recombinant E. coli bacteria were cultured, with which the chemotaxis of E. coli was studied in order to determine the influence of antibiotic ciprofloxacin concentration on the E. coli migration. The chip bonded with cyanoacrylate-based resin was tested by measuring protein concentration and carrying out DNA capillary electrophoresis. To study the biocompatibility and applicability of our microfluidic chip fabrication technology, we tested the PCR compatibility of our chip materials along with various other common materials

A microfluidic cell culture array with various oxygen tensions.

Science.gov (United States)

Peng, Chien-Chung; Liao, Wei-Hao; Chen, Ying-Hua; Wu, Chueh-Yu; Tung, Yi-Chung

2013-08-21

Oxygen tension plays an important role in regulating various cellular functions in both normal physiology and disease states. Therefore, drug testing using conventional in vitro cell models under normoxia often possesses limited prediction capability. A traditional method of setting an oxygen tension in a liquid medium is by saturating it with a gas mixture at the desired level of oxygen, which requires bulky gas cylinders, sophisticated control, and tedious interconnections. Moreover, only a single oxygen tension can be tested at the same time. In this paper, we develop a microfluidic cell culture array platform capable of performing cell culture and drug testing under various oxygen tensions simultaneously. The device is fabricated using an elastomeric material, polydimethylsiloxane (PDMS) and the well-developed multi-layer soft lithography (MSL) technique. The prototype device has 4 × 4 wells, arranged in the same dimensions as a conventional 96-well plate, for cell culture. The oxygen tensions are controlled by spatially confined oxygen scavenging chemical reactions underneath the wells using microfluidics. The platform takes advantage of microfluidic phenomena while exhibiting the combinatorial diversities achieved by microarrays. Importantly, the platform is compatible with existing cell incubators and high-throughput instruments (liquid handling systems and plate readers) for cost-effective setup and straightforward operation. Utilizing the developed platform, we successfully perform drug testing using an anti-cancer drug, triapazamine (TPZ), on adenocarcinomic human alveolar basal epithelial cell line (A549) under three oxygen tensions ranging from 1.4% to normoxia. The developed platform is promising to provide a more meaningful in vitro cell model for various biomedical applications while maintaining desired high throughput capabilities.

Capture of DNA in microfluidic channel using magnetic beads: increasing capture efficiency with integrated microfluidic mixer

DEFF Research Database (Denmark)

Lund-Olesen, Torsten; Dufva, Hans Martin; Hansen, Mikkel Fougt

2007-01-01

We have studied the hybridization of target DNA in solution with probe DNA on magnetic beads immobilized on the channel sidewalls in a magnetic bead separator. The hybridization is carried out under a liquid flow and is diffusion limited. Two systems are compared: one with a straight microfluidic...... place on the surface in a microfluidic system....

Construction of programmable interconnected 3D microfluidic networks

International Nuclear Information System (INIS)

Hunziker, Patrick R; Wolf, Marc P; Wang, Xueya; Zhang, Bei; Marsch, Stephan; Salieb-Beugelaar, Georgette B

2015-01-01

Microfluidic systems represent a key-enabling platform for novel diagnostic tools for use at the point-of-care in clinical contexts as well as for evolving single cell diagnostics. The design of 3D microfluidic systems is an active field of development, but construction of true interconnected 3D microfluidic networks is still a challenge, in particular when the goal is rapid prototyping, accurate design and flexibility. We report a novel approach for the construction of programmable 3D microfluidic systems consisting of modular 3D template casting of interconnected threads to allow user-programmable flow paths and examine its structural characteristics and its modular function. To overcome problems with thread template casting reported in the literature, low-surface-energy polymer threads were used, that allow solvent-free production. Connected circular channels with excellent roundness and low diameter variability were created. Variable channel termination allowed programming a flow path on-the-fly, thus rendering the resulting 3D microfluidic systems highly customizable even after production. Thus, construction of programmable/reprogrammable fully 3D microfluidic systems by template casting of a network of interconnecting threads is feasible, leads to high-quality and highly reproducible, complex 3D geometries. (paper)

Microfluidic-integrated biosensors: prospects for point-of-care diagnostics.

Science.gov (United States)

Kumar, Suveen; Kumar, Saurabh; Ali, Md Azahar; Anand, Pinki; Agrawal, Ved Varun; John, Renu; Maji, Sagar; Malhotra, Bansi D

2013-11-01

There is a growing demand to integrate biosensors with microfluidics to provide miniaturized platforms with many favorable properties, such as reduced sample volume, decreased processing time, low cost analysis and low reagent consumption. These microfluidics-integrated biosensors would also have numerous advantages such as laminar flow, minimal handling of hazardous materials, multiple sample detection in parallel, portability and versatility in design. Microfluidics involves the science and technology of manipulation of fluids at the micro- to nano-liter level. It is predicted that combining biosensors with microfluidic chips will yield enhanced analytical capability, and widen the possibilities for applications in clinical diagnostics. The recent developments in microfluidics have helped researchers working in industries and educational institutes to adopt some of these platforms for point-of-care (POC) diagnostics. This review focuses on the latest advancements in the fields of microfluidic biosensing technologies, and on the challenges and possible solutions for translation of this technology for POC diagnostic applications. We also discuss the fabrication techniques required for developing microfluidic-integrated biosensors, recently reported biomarkers, and the prospects of POC diagnostics in the medical industry. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New microfluidic platform for life sciences in South Africa

CSIR Research Space (South Africa)

Hugo, S

2012-10-01

Full Text Available is also offered as numerous devices can be implemented on one disc. A variety of components from sample preparation through to detection can be implemented simply and effectively into an integrated microfluidic solution for life sciences. The lab... in the field of centrifugal microfluidics. New microfluidic platform for life sciences in South Africa S. HUGO, K. LAND CSIR Materials Science and Manufacturing P O Box 395, Pretoria 0001, SOUTH AFRICA Email: kland@csir.co.za INTRODUCTION Microfluidic...

Blood–plasma separation in Y-shaped bifurcating microfluidic channels: a dissipative particle dynamics simulation study

International Nuclear Information System (INIS)

Li, Xuejin; Karniadakis, George Em; Popel, Aleksander S

2012-01-01

The motion of a suspension of red blood cells (RBCs) flowing in a Y-shaped bifurcating microfluidic channel is investigated using a validated low-dimensional RBC model based on dissipative particle dynamics. Specifically, the RBC is represented as a closed torus-like ring of ten colloidal particles, which leads to efficient simulations of blood flow in microcirculation over a wide range of hematocrits. Adaptive no-slip wall boundary conditions were implemented to model hydrodynamic flow within a specific wall structure of diverging three-dimensional microfluidic channels, paying attention to controlling density fluctuations. Plasma skimming and the all-or-nothing phenomenon of RBCs in a bifurcating microfluidic channel have been investigated in our simulations for healthy and diseased blood, including the size of a cell-free layer on the daughter branches. The feed hematocrit level in the parent channel has considerable influence on blood–plasma separation. Compared to the blood–plasma separation efficiencies of healthy RBCs, malaria-infected stiff RBCs (iRBCs) have a tendency to travel into the low flow-rate daughter branch because of their different initial distribution in the parent channel. Our simulation results are consistent with previously published experimental results and theoretical predictions. (paper)

Design and validation of a microfluidic device for blood-brain barrier monitoring and transport studies

Science.gov (United States)

Ugolini, Giovanni Stefano; Occhetta, Paola; Saccani, Alessandra; Re, Francesca; Krol, Silke; Rasponi, Marco; Redaelli, Alberto

2018-04-01

In vitro blood-brain barrier models are highly relevant for drug screening and drug development studies, due to the challenging task of understanding the transport mechanism of drug molecules through the blood-brain barrier towards the brain tissue. In this respect, microfluidics holds potential for providing microsystems that require low amounts of cells and reagent and can be potentially multiplexed for increasing the ease and throughput of the drug screening process. We here describe the design, development and validation of a microfluidic device for endothelial blood-brain barrier cell transport studies. The device comprises of two microstructured layers (top culture chamber and bottom collection chamber) sandwiching a porous membrane for the cell culture. Microstructured layers include two pairs of physical electrodes, embedded into the device layers by geometrically defined guiding channels with computationally optimized positions. These electrodes allow the use of commercial electrical measurement systems for monitoring trans-endothelial electrical resistance (TEER). We employed the designed device for performing preliminary assessment of endothelial barrier formation with murine brain endothelial cells (Br-bEnd5). Results demonstrate that cellular junctional complexes effectively form in the cultures (expression of VE-Cadherin and ZO-1) and that the TEER monitoring systems effectively detects an increase of resistance of the cultured cell layers indicative of tight junction formation. Finally, we validate the use of the described microsystem for drug transport studies demonstrating that Br-bEnd5 cells significantly hinder the transport of molecules (40 kDa and 4 kDa dextran) from the top culture chamber to the bottom collection chamber.

Effect of a dual inlet channel on cell loading in microfluidics.

Science.gov (United States)

Yun, Hoyoung; Kim, Kisoo; Lee, Won Gu

2014-11-01

Unwanted sedimentation and attachment of a number of cells onto the bottom channel often occur on relatively large-scale inlets of conventional microfluidic channels as a result of gravity and fluid shear. Phenomena such as sedimentation have become recognized problems that can be overcome by performing microfluidic experiments properly, such as by calculating a meaningful output efficiency with respect to real input. Here, we present a dual-inlet design method for reducing cell loss at the inlet of channels by adding a new " upstream inlet " to a single main inlet design. The simple addition of an upstream inlet can create a vertically layered sheath flow prior to the main inlet for cell loading. The bottom layer flow plays a critical role in preventing the cells from attaching to the bottom of the channel entrance, resulting in a low possibility of cell sedimentation at the main channel entrance. To provide proof-of-concept validation, we applied our design to a microfabricated flow cytometer system (μFCS) and compared the cell counting efficiency of the proposed μFCS with that of the previous single-inlet μFCS and conventional FCS. We used human white blood cells and fluorescent microspheres to quantitatively evaluate the rate of cell sedimentation in the main inlet and to measure fluorescence sensitivity at the detection zone of the flow cytometer microchip. Generating a sheath flow as the bottom layer was meaningfully used to reduce the depth of field as well as the relative deviation of targets in the z-direction (compared to the x-y flow plane), leading to an increased counting sensitivity of fluorescent detection signals. Counting results using fluorescent microspheres showed both a 40% reduction in the rate of sedimentation and a 2-fold higher sensitivity in comparison with the single-inlet μFCS. The results of CD4(+) T-cell counting also showed that the proposed design results in a 25% decrease in the rate of cell sedimentation and a 28% increase in

Fabrication of Microfluidic Valves Using a Hydrogel Molding Method.

Science.gov (United States)

Sugiura, Yusuke; Hirama, Hirotada; Torii, Toru

2015-08-24

In this paper, a method for fabricating a microfluidic valve made of polydimethylsiloxane (PDMS) using a rapid prototyping method for microchannels through hydrogel cast molding is discussed. Currently, the valves in microchannels play an important role in various microfluidic devices. The technology to prototype microfluidic valves rapidly is actively being developed. For the rapid prototyping of PDMS microchannels, a method that uses a hydrogel as the casting mold has been recently developed. This technique can be used to prepare a three-dimensional structure through simple and uncomplicated methods. In this study, we were able to fabricate microfluidic valves easily using this rapid prototyping method that utilizes hydrogel cast molding. In addition, we confirmed that the valve displacement could be predicted within a range of constant pressures. Moreover, because microfluidic valves fabricated using this method can be directly observed from a cross-sectional direction, we anticipate that this technology will significantly contribute to clarifying fluid behavior and other phenomena in microchannels and microfluidic valves with complex structures.

Microfluidic redox battery.

Science.gov (United States)

Lee, Jin Wook; Goulet, Marc-Antoni; Kjeang, Erik

2013-07-07

A miniaturized microfluidic battery is proposed, which is the first membraneless redox battery demonstrated to date. This unique concept capitalizes on dual-pass flow-through porous electrodes combined with stratified, co-laminar flow to generate electrical power on-chip. The fluidic design is symmetric to allow for both charging and discharging operations in forward, reverse, and recirculation modes. The proof-of-concept device fabricated using low-cost materials integrated in a microfluidic chip is shown to produce competitive power levels when operated on a vanadium redox electrolyte. A complete charge/discharge cycle is performed to demonstrate its operation as a rechargeable battery, which is an important step towards providing sustainable power to lab-on-a-chip and microelectronic applications.

Routing-based Synthesis of Digital Microfluidic Biochips

DEFF Research Database (Denmark)

Maftei, Elena; Pop, Paul; Madsen, Jan

2010-01-01

Microfluidic biochips are replacing the conventional biochemical analyzers, and are able to integrate on-chip all the basic functsions for biochemical analysis. The "digital" microfluidic biochips are manipulating liquids not as a continuous flow, but as discrete droplets on a two-dimensional array...... of electrodes. Basic microfluidic operations, such as mixing and dilution, are performed on the array, by routing the corresponding droplets on a series of electrodes. So far, researchers have assumed that these operations are executed on rectangular virtual devices, formed by grouping several adjacent...

Assembly of multiple cell gradients directed by three-dimensional microfluidic channels.

Science.gov (United States)

Li, Yiwei; Feng, Xiaojun; Wang, Yachao; Du, Wei; Chen, Peng; Liu, Chao; Liu, Bi-Feng

2015-08-07

Active control over the cell gradient is essential for understanding biological systems and the reconstitution of the functionality of many types of tissues, particularly for organ-on-a-chip. Here, we propose a three-dimensional (3D) microfluidic strategy for generating controllable cell gradients. In this approach, a homogeneous cell suspension is loaded into a 3D stair-shaped PDMS microchannel to generate a cell gradient within 10 min by sedimentation. We demonstrate that cell gradients of various profiles (exponential and piecewise linear) can be achieved by precisely controlling the height of each layer during the fabrication. With sequential seeding, we further demonstrate the generation of two overlapping cell gradients on the same glass substrate with pre-defined designs. The cell gradient-based QD cytotoxicity assay also demonstrated that cell behaviors and resistances were regulated by the changes in cell density. These results reveal that the proposed 3D microfluidic strategy provides a simple and versatile means for establishing controllable gradients in cell density, opening up a new avenue for reconstructing functional tissues.

Soft tubular microfluidics for 2D and 3D applications

Science.gov (United States)

Xi, Wang; Kong, Fang; Yeo, Joo Chuan; Yu, Longteng; Sonam, Surabhi; Dao, Ming; Gong, Xiaobo; Teck Lim, Chwee

2017-10-01

Microfluidics has been the key component for many applications, including biomedical devices, chemical processors, microactuators, and even wearable devices. This technology relies on soft lithography fabrication which requires cleanroom facilities. Although popular, this method is expensive and labor-intensive. Furthermore, current conventional microfluidic chips precludes reconfiguration, making reiterations in design very time-consuming and costly. To address these intrinsic drawbacks of microfabrication, we present an alternative solution for the rapid prototyping of microfluidic elements such as microtubes, valves, and pumps. In addition, we demonstrate how microtubes with channels of various lengths and cross-sections can be attached modularly into 2D and 3D microfluidic systems for functional applications. We introduce a facile method of fabricating elastomeric microtubes as the basic building blocks for microfluidic devices. These microtubes are transparent, biocompatible, highly deformable, and customizable to various sizes and cross-sectional geometries. By configuring the microtubes into deterministic geometry, we enable rapid, low-cost formation of microfluidic assemblies without compromising their precision and functionality. We demonstrate configurable 2D and 3D microfluidic systems for applications in different domains. These include microparticle sorting, microdroplet generation, biocatalytic micromotor, triboelectric sensor, and even wearable sensing. Our approach, termed soft tubular microfluidics, provides a simple, cheaper, and faster solution for users lacking proficiency and access to cleanroom facilities to design and rapidly construct microfluidic devices for their various applications and needs.

"Connecting worlds - a view on microfluidics for a wider application".

Science.gov (United States)

Fernandes, Ana C; Gernaey, Krist V; Krühne, Ulrich

From its birth, microfluidics has been referenced as a revolutionary technology and the solution to long standing technological and sociological issues, such as detection of dilute compounds and personalized healthcare. Microfluidics has for example been envisioned as: (1) being capable of miniaturizing industrial production plants, thereby increasing their automation and operational safety at low cost; (2) being able to identify rare diseases by running bioanalytics directly on the patient's skin; (3) allowing health diagnostics in point-of-care sites through cheap lab-on-a-chip devices. However, the current state of microfluidics, although technologically advanced, has so far failed to reach the originally promised widespread use. In this paper, some of the aspects are identified and discussed that have prevented microfluidics from reaching its full potential, especially in the chemical engineering and biotechnology fields, focusing mainly on the specialization on a single target of most microfluidic devices and offering a perspective on the alternate, multi-use, "plug and play" approach. Increasing the flexibility of microfluidic platforms, by increasing their compatibility with different substrates, reactions and operation conditions, and other microfluidic systems is indeed of surmount importance and current academic and industrial approaches to modular microfluidics are presented. Furthermore, two views on the commercialization of plug-and-play microfluidics systems, leading towards improved acceptance and more widespread use, are introduced. A brief review of the main materials and fabrication strategies used in these fields, is also presented. Finally, a step-wise guide towards the development of microfluidic systems is introduced with special focus on the integration of sensors in microfluidics. The proposed guidelines are then applied for the development of two different example platforms, and to three examples taken from literature. With this work, we

Synthesis of Freestanding Single-crystal Perovskite Films and Heterostructures by Etching of Sacrificial Water-soluble Layers

Energy Technology Data Exchange (ETDEWEB)

Lu, Di; Baek, David J.; Hong, Seung Sae; Kourkoutis, Lena F.; Hikita, Yasuyuki; Hwang, Harold Y.

2016-08-22

The ability to create and manipulate materials in two-dimensional (2D) form has repeatedly had transformative impact on science and technology. In parallel with the exfoliation and stacking of intrinsically layered crystals, atomic-scale thin film growth of complex materials has enabled the creation of artificial 2D heterostructures with novel functionality and emergent phenomena, as seen in perovskite heterostructures. However, separation of these layers from the growth substrate has proven challenging, limiting the manipulation capabilities of these heterostructures with respect to exfoliated materials. Here we present a general method to create freestanding perovskite membranes. The key is the epitaxial growth of water-soluble Sr₃Al₂O₆ on perovskite substrates, followed by in situ growth of films and heterostructures. Millimetre-size single-crystalline membranes are produced by etching the Sr₃Al₂O₆ layer in water, providing the opportunity to transfer them to arbitrary substrates and integrate them with heterostructures of semiconductors and layered compounds.

Microfluidics as a functional tool for cell mechanics.

Science.gov (United States)

Vanapalli, Siva A; Duits, Michel H G; Mugele, Frieder

2009-01-05

Living cells are a fascinating demonstration of nature's most intricate and well-coordinated micromechanical objects. They crawl, spread, contract, and relax-thus performing a multitude of complex mechanical functions. Alternatively, they also respond to physical and chemical cues that lead to remodeling of the cytoskeleton. To understand this intricate coupling between mechanical properties, mechanical function and force-induced biochemical signaling requires tools that are capable of both controlling and manipulating the cell microenvironment and measuring the resulting mechanical response. In this review, the power of microfluidics as a functional tool for research in cell mechanics is highlighted. In particular, current literature is discussed to show that microfluidics powered by soft lithographic techniques offers the following capabilities that are of significance for understanding the mechanical behavior of cells: (i) Microfluidics enables the creation of in vitro models of physiological environments in which cell mechanics can be probed. (ii) Microfluidics is an excellent means to deliver physical cues that affect cell mechanics, such as cell shape, fluid flow, substrate topography, and stiffness. (iii) Microfluidics can also expose cells to chemical cues, such as growth factors and drugs, which alter their mechanical behavior. Moreover, these chemical cues can be delivered either at the whole cell or subcellular level. (iv) Microfluidic devices offer the possibility of measuring the intrinsic mechanical properties of cells in a high throughput fashion. (v) Finally, microfluidic methods provide exquisite control over drop size, generation, and manipulation. As a result, droplets are being increasingly used to control the physicochemical environment of cells and as biomimetic analogs of living cells. These powerful attributes of microfluidics should further stimulate novel means of investigating the link between physicochemical cues and the biomechanical

‘Chip-olate’ and dry-film resists for efficient fabrication, singulation and sealing of microfluidic chips

Science.gov (United States)

Temiz, Yuksel; Delamarche, Emmanuel

2014-09-01

This paper describes a technique for high-throughput fabrication and efficient singulation of chips having closed microfluidic structures and takes advantage of dry-film resists (DFRs) for efficient sealing of capillary systems. The technique is illustrated using 4-inch Si/SiO2 wafers. Wafers carrying open microfluidic structures are partially diced to about half of their thickness. Treatments such as surface cleaning are done at wafer-level, then the structures are sealed using low-temperature (45 °C) lamination of a DFR that is pre-patterned using a craft cutter, and ready-to-use chips are finally separated manually like a chocolate bar by applying a small force (≤ 4 N). We further show that some DFRs have low auto-fluorescence at wavelengths typically used for common fluorescent dyes and that mechanical properties of some DFRs allow for the lamination of 200 μm wide microfluidic structures with negligible sagging (~1 μm). The hydrophilicity (advancing contact angle of ~60°) of the DFR supports autonomous capillary-driven flow without the need for additional surface treatment of the microfluidic chips. Flow rates from 1 to 5 µL min-1 are generated using different geometries of channels and capillary pumps. In addition, the ‘chip-olate’ technique is compatible with the patterning of capture antibodies on DFR for use in immunoassays. We believe this technique to be applicable to the fabrication of a wide range of microfluidic and lab-on-a-chip devices and to offer a viable alternative to many labor-intensive processes that are currently based on wafer bonding techniques or on the molding of poly(dimethylsiloxane) (PDMS) layers.

A Microfluidic Cell Concentrator

Science.gov (United States)

Warrick, Jay; Casavant, Ben; Frisk, Megan; Beebe, David

2010-01-01

Cell concentration via centrifugation is a ubiquitous step in many cell culture procedures. At the macroscale, centrifugation suffers from a number of limitations particularly when dealing with small numbers of cells (e.g., less than 50,000). On the other hand, typical microscale methods for cell concentration can affect cell physiology and bias readouts of cell behavior and function. In this paper, we present a microfluidic concentrator device that utilizes the effects of gravity to allow cells to gently settle out of a suspension into a collection region without the use of specific adhesion ligands. Dimensional analysis was performed to compare different device designs and was verified with flow modeling to optimize operational parameters. We are able to concentrate low-density cell suspensions in a microfluidic chamber, achieving a cell loss of only 1.1 ± 0.6% (SD, n=7) with no observed loss during a subsequent cell staining protocol which incorporates ~36 complete device volume replacements. This method provides a much needed interface between rare cell samples and microfluidic culture assays. PMID:20843010

Microfluidics with fluid walls.

Science.gov (United States)

Walsh, Edmond J; Feuerborn, Alexander; Wheeler, James H R; Tan, Ann Na; Durham, William M; Foster, Kevin R; Cook, Peter R

2017-10-10

Microfluidics has great potential, but the complexity of fabricating and operating devices has limited its use. Here we describe a method - Freestyle Fluidics - that overcomes many key limitations. In this method, liquids are confined by fluid (not solid) walls. Aqueous circuits with any 2D shape are printed in seconds on plastic or glass Petri dishes; then, interfacial forces pin liquids to substrates, and overlaying an immiscible liquid prevents evaporation. Confining fluid walls are pliant and resilient; they self-heal when liquids are pipetted through them. We drive flow through a wide range of circuits passively by manipulating surface tension and hydrostatic pressure, and actively using external pumps. Finally, we validate the technology with two challenging applications - triggering an inflammatory response in human cells and chemotaxis in bacterial biofilms. This approach provides a powerful and versatile alternative to traditional microfluidics.The complexity of fabricating and operating microfluidic devices limits their use. Walsh et al. describe a method in which circuits are printed as quickly and simply as writing with a pen, and liquids in them are confined by fluid instead of solid walls.

Pulsed laser triggered high speed microfluidic fluorescence activated cell sorter†‡

Science.gov (United States)

Wu, Ting-Hsiang; Chen, Yue; Park, Sung-Yong; Hong, Jason; Teslaa, Tara; Zhong, Jiang F.; Di Carlo, Dino; Teitell, Michael A.

2014-01-01

We report a high speed and high purity pulsed laser triggered fluorescence activated cell sorter (PLACS) with a sorting throughput up to 20 000 mammalian cells s−1 with 37% sorting purity, 90% cell viability in enrichment mode, and >90% purity in high purity mode at 1500 cells s−1 or 3000 beads s−1. Fast switching (30 μs) and a small perturbation volume (~90 pL) is achieved by a unique sorting mechanism in which explosive vapor bubbles are generated using focused laser pulses in a single layer microfluidic PDMS channel. PMID:22361780

Effect of sacrificial agents on the dispersion of metal cocatalysts for photocatalytic hydrogen evolution

Science.gov (United States)

Cao, Shaowen; Shen, Baojia; Huang, Qian; Chen, Zhe

2018-06-01

Surface photodeposition of noble metal cocatalyst has been regarded as an effective approach to facilitate the separation of charge carriers and reduce the over-potential of water reduction, thus to enhance the photocatalytic H2-production activities of semiconductor photocatalyst. Herein, the influences of sacrificial agents used in the photodeposition process on the dispersion of noble metal nanoparticles are investigated, via a series of technique of photocatalytic hydrogen evolution test, microstructure analysis and photoelectrochemical measurement. As a result, the sacrificial agents are found to show large impact on the loading amount, particle size and distribution of different metals on the surface of g-C3N4. The real loading amount of Pt and Au is higher in methanol solution than that in triethanolamine solution. Better distribution and smaller size of Pt nanoparticles are achieved in the presence of methanol; while better distribution and smaller size of Au nanoparticles are achieved in the presence of triethanolamine. As a result, quite different charge transfer ability is achieved for the synthesized Pt and Au decorated g-C3N4, which subsequently leads to disparate photocatalytic activities of the same g-C3N4 photocatalyst under various conditions. The finding in this work indicates that the valid deposition content, particle size and distribution of metal cocatalysts should be carefully taken into account when comparing the photocatalytic activities among various samples.

A self-loading microfluidic device for determining the minimum inhibitory concentration of antibiotics.

Science.gov (United States)

Cira, Nate J; Ho, Jack Y; Dueck, Megan E; Weibel, Douglas B

2012-03-21

This article describes a portable microfluidic technology for determining the minimum inhibitory concentration (MIC) of antibiotics against bacteria. The microfluidic platform consists of a set of chambers molded in poly(dimethylsiloxane) (PDMS) that are preloaded with antibiotic, dried, and reversibly sealed to a second layer of PDMS containing channels that connect the chambers. The assembled device is degassed via vacuum prior to its use, and the absorption of gas by PDMS provides the mechanism for actuating and metering the flow of fluid in the microfluidic channels and chambers. During the operation of the device, degas driven flow introduces a suspension of bacterial cells, dissolves the antibiotic, and isolates cells in individual chambers without cross contamination. The growth of bacteria in the chambers in the presence of a pH indicator produces a colorimetric change that can be detected visually using ambient light. Using this device we measured the MIC of vancomycin, tetracycline, and kanamycin against Enterococcus faecalis 1131, Proteus mirabilis HI4320, Klebsiella pneumoniae, and Escherichia coli MG1655 and report values that are comparable to standard liquid broth dilution measurements. The device provides a simple method for MIC determination of individual antibiotics against human pathogens that will have applications for clinical and point-of-care medicine. Importantly, this device is designed around simplicity: it requires a single pipetting step to introduce the sample, no additional components or external equipment for its operation, and provides a straightforward visual measurement of cell growth. As the device introduces a novel approach for filling and isolating dead-end microfluidic chambers that does not require valves and actuators, this technology should find applications in other portable assays and devices.

Fluorescence detection system for microfluidic droplets

Science.gov (United States)

Chen, Binyu; Han, Xiaoming; Su, Zhen; Liu, Quanjun

2018-05-01

In microfluidic detection technology, because of the universality of optical methods in laboratory, optical detection is an attractive solution for microfluidic chip laboratory equipment. In addition, the equipment with high stability and low cost can be realized by integrating appropriate optical detection technology on the chip. This paper reports a detection system for microfluidic droplets. Photomultiplier tubes (PMT) is used as a detection device to improve the sensitivity of detection. This system improves the signal to noise ratio by software filtering and spatial filter. The fluorescence intensity is proportional to the concentration of the fluorescence and intensity of the laser. The fluorescence micro droplets of different concentrations can be distinguished by this system.

Inkjet 3D printing of microfluidic structures—on the selection of the printer towards printing your own microfluidic chips

International Nuclear Information System (INIS)

Walczak, Rafał; Adamski, Krzysztof

2015-01-01

This article reports, for the first time, the results of detailed research on the application of inkjet 3D printing for the fabrication of microfluidic structures. CAD designed test structures were printed with four different printers. Dimensional fidelity, shape conformity, and surface roughness were studied for each printout. It was found that the minimum dimension (width or depth) for a properly printed microfluidic channel was approximately 200 μm. Although the nominal resolution of the printers was one order of magnitude better, smaller structures were significantly deformed or not printed at all. It was also found that a crucial step in one-step fabrication of embedded microchannels is the removal of the support material. We also discuss the source of print error and present a way to evaluate other printers. The printouts obtained from the four different printers were compared, and the optimal printing technique and printer were used to fabricate a microfluidic structure for the spectrophotometric characterisation of beverages. UV/VIS absorbance characteristics were collected using this microfluidic structure, demonstrating that the fabricated spectrophotometric chip operated properly. Thus, a proof-of-concept for using inkjet 3D printing for the fabrication of microfluidic structures was obtained. (paper)

Fast Prototyping of Sensorized Cell Culture Chips and Microfluidic Systems with Ultrashort Laser Pulses

Directory of Open Access Journals (Sweden)

Sebastian M. Bonk

2015-03-01

Full Text Available We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO plating or were prepared from platinum sputtering (100 nm onto a 10-nm titanium adhesion layer. Direct processing of the sensor structures (approximately three minutes per chip by an ultrashort pulse laser facilitated the production of the prototypes. pH-sensitive areas were produced by the sputtering of 60-nm Si3N4 through a simple mask made from a circuit board material. The system body and polydimethylsiloxane (PDMS molding forms for the microfluidic structures were manufactured by micromilling using a printed circuit board (PCB milling machine for circuit boards. The microfluidic structure was finally imprinted in PDMS. Our approach avoided the use of photolithographic techniques and enabled fast and cost-efficient prototyping of the systems. Alternatively, the direct production of metallic, ceramic or polymeric molding tools was tested. The use of ultrashort pulse lasers improved the precision of the structures and avoided any contact of the final structures with toxic chemicals and possible adverse effects for the cell culture in lab-on-a-chip systems.

Opportunities for microfluidic technologies in synthetic biology

OpenAIRE

Gulati, Shelly; Rouilly, Vincent; Niu, Xize; Chappell, James; Kitney, Richard I.; Edel, Joshua B.; Freemont, Paul S.; deMello, Andrew J.

2009-01-01

We introduce microfluidics technologies as a key foundational technology for synthetic biology experimentation. Recent advances in the field of microfluidics are reviewed and the potential of such a technological platform to support the rapid development of synthetic biology solutions is discussed.

Integrating Carbon Nanotubes into Microfluidic Chip for Separating Biochemical Compounds

DEFF Research Database (Denmark)

Chen, Miaoxiang Max; Mogensen, Klaus Bo; Bøggild, Peter

2012-01-01

We present a new type of device to separate biochemical compounds wherein carbon nanotubes (CNTs) are integrated as chromatographic stationary phase. The CNTs were directly grown on the bottom of microfluidic channels on Si/SiO2 substrates by chemical vapor deposition (CVD). Acetylene was used...... as carbon source and Ni was employed as catalyst. For electrokinetic separations, higher electrical field strength is usually required; therefore, the CNTs were constructed in pillar-array-form by patterning the catalyst layer. Electrical field strength of 2.0 kV/cm has been realized, which is more than one...

Microfluidics without channels: highly-flexible synthesis on a digital-microfluidic chip for production of diverse PET tracers

Energy Technology Data Exchange (ETDEWEB)

Van Dam, Robert Michael [Univ. of California, Los Angeles, CA (United States)

2010-09-01

Positron emission tomography (PET) imaging is used for fundamental studies of living biological organisms and microbial ecosystems in applications ranging from biofuel production to environmental remediation to the study, diagnosis, and treatment monitoring of human disease. Routine access to PET imaging, to monitor biochemical reactions in living organisms in real time, could accelerate a broad range of research programs of interest to DOE. Using PET requires access to short-lived radioactive-labeled compounds that specifically probe the desired living processes. The overall aims of this project were to develop a miniature liquid-handling technology platform (called “microfluidics”) that increases the availability of diverse PET probes by reducing the cost and complexity of their production. Based on preliminary experiments showing that microfluidic chips can synthesis such compounds, we aimed to advance this technology to improve its robustness, increase its flexibility for a broad range of probes, and increase its user-friendliness. Through the research activities of this project, numerous advances were made; Tools were developed to enable the visualization of radioactive materials within microfluidic chips; Fundamental advances were made in the microfluidic chip architecture and fabrication process to increase its robustness and reliability; The microfluidic chip technology was shown to produce useful quantities of an example PET probes, and methods to further increase the output were successfully pursued; A “universal” chip was developed that could produce multiple types of PET probes, enabling the possibility of “on demand” synthesis of different probes; and Operation of the chip was automated to ensure minimal radiation exposure to the operator Based on the demonstrations of promising technical feasibility and performance, the microfluidic chip technology is currently being commercialized. It is anticipated that costs of microfluidic chips can be

Detection methods for centrifugal microfluidic platforms

DEFF Research Database (Denmark)

Burger, Robert; Amato, Letizia; Boisen, Anja

2016-01-01

Centrifugal microfluidics has attracted much interest from academia as well as industry, since it potentially offers solutions for affordable, user-friendly and portable biosensing. A wide range of so-called fluidic unit operations, e.g. mixing, metering, liquid routing, and particle separation...... for the centrifugal microfluidics platform and cover optical as well as mechanical and electrical detection principles....

Theoretical microfluidics

DEFF Research Database (Denmark)

Bruus, Henrik

Microfluidics is a young and rapidly expanding scientific discipline, which deals with fluids and solutions in miniaturized systems, the so-called lab-on-a-chip systems. It has applications in chemical engineering, pharmaceutics, biotechnology and medicine. As the lab-on-a-chip systems grow...

Rapid, low-cost prototyping of centrifugal microfluidic devices for effective implementation of various microfluidic operations

CSIR Research Space (South Africa)

Hugo, S

2013-10-01

Full Text Available can be achieved. This work provides a complete centrifugal microfluidic platform and the building blocks on which to develop a variety of microfluidic applications and potential products rapidly and at a low cost. ... stream_source_info Hugo_2015_ABSTRACT.pdf.txt stream_content_type text/plain stream_size 1281 Content-Encoding UTF-8 stream_name Hugo_2015_ABSTRACT.pdf.txt Content-Type text/plain; charset=UTF-8 Rapid Product Development...

Design of pressure-driven microfluidic networks using electric circuit analogy.

Science.gov (United States)

Oh, Kwang W; Lee, Kangsun; Ahn, Byungwook; Furlani, Edward P

2012-02-07

This article reviews the application of electric circuit methods for the analysis of pressure-driven microfluidic networks with an emphasis on concentration- and flow-dependent systems. The application of circuit methods to microfluidics is based on the analogous behaviour of hydraulic and electric circuits with correlations of pressure to voltage, volumetric flow rate to current, and hydraulic to electric resistance. Circuit analysis enables rapid predictions of pressure-driven laminar flow in microchannels and is very useful for designing complex microfluidic networks in advance of fabrication. This article provides a comprehensive overview of the physics of pressure-driven laminar flow, the formal analogy between electric and hydraulic circuits, applications of circuit theory to microfluidic network-based devices, recent development and applications of concentration- and flow-dependent microfluidic networks, and promising future applications. The lab-on-a-chip (LOC) and microfluidics community will gain insightful ideas and practical design strategies for developing unique microfluidic network-based devices to address a broad range of biological, chemical, pharmaceutical, and other scientific and technical challenges.

Synthesis of Application-Specific Fault-Tolerant Digital Microfluidic Biochip Architectures

DEFF Research Database (Denmark)

Alistar, Mirela; Pop, Paul; Madsen, Jan

2016-01-01

Digital microfluidic biochips (DMBs) are microfluidic devices that manipulate droplets on an array of electrodes. Microfluidic operations, such as transport, mixing, and split, are performed on the electrode array to perform a biochemical application. All previous work assumes that the DMB...

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

Science.gov (United States)

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

2010-06-01

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

Synthetic microfluidic paper: high surface area and high porosity polymer micropillar arrays.

Science.gov (United States)

Hansson, Jonas; Yasuga, Hiroki; Haraldsson, Tommy; van der Wijngaart, Wouter

2016-01-21

We introduce Synthetic Microfluidic Paper, a novel porous material for microfluidic applications that consists of an OSTE polymer that is photostructured in a well-controlled geometry of slanted and interlocked micropillars. We demonstrate the distinct benefits of Synthetic Microfluidic Paper over other porous microfluidic materials, such as nitrocellulose, traditional paper and straight micropillar arrays: in contrast to straight micropillar arrays, the geometry of Synthetic Microfluidic Paper was miniaturized without suffering capillary collapse during manufacturing and fluidic operation, resulting in a six-fold increased internal surface area and a three-fold increased porous fraction. Compared to commercial nitrocellulose materials for capillary assays, Synthetic Microfluidic Paper shows a wider range of capillary pumping speed and four times lower device-to-device variation. Compared to the surfaces of the other porous microfluidic materials that are modified by adsorption, Synthetic Microfluidic Paper contains free thiol groups and has been shown to be suitable for covalent surface chemistry, demonstrated here for increasing the material hydrophilicity. These results illustrate the potential of Synthetic Microfluidic Paper as a porous microfluidic material with improved performance characteristics, especially for bioassay applications such as diagnostic tests.

Diffusion phenomena of cells and biomolecules in microfluidic devices.

Science.gov (United States)

Yildiz-Ozturk, Ece; Yesil-Celiktas, Ozlem

2015-09-01

Biomicrofluidics is an emerging field at the cross roads of microfluidics and life sciences which requires intensive research efforts in terms of introducing appropriate designs, production techniques, and analysis. The ultimate goal is to deliver innovative and cost-effective microfluidic devices to biotech, biomedical, and pharmaceutical industries. Therefore, creating an in-depth understanding of the transport phenomena of cells and biomolecules becomes vital and concurrently poses significant challenges. The present article outlines the recent advancements in diffusion phenomena of cells and biomolecules by highlighting transport principles from an engineering perspective, cell responses in microfluidic devices with emphases on diffusion- and flow-based microfluidic gradient platforms, macroscopic and microscopic approaches for investigating the diffusion phenomena of biomolecules, microfluidic platforms for the delivery of these molecules, as well as the state of the art in biological applications of mammalian cell responses and diffusion of biomolecules.

Patterning of PMMA microfluidic parts using screen printing process

Science.gov (United States)

Ahari Kaleibar, Aminreza; Rahbar, Mona; Haiducu, Marius; Parameswaran, Ash M.

2010-02-01

An inexpensive and rapid micro-fabrication process for producing PMMA microfluidic components has been presented. Our proposed technique takes advantages of commercially available economical technologies such as the silk screen printing and UV patterning of PMMA substrates to produce the microfluidic components. As a demonstration of our proposed technique, we had utilized a homemade deep-UV source, λ=254nm, a silk screen mask made using a local screen-printing shop and Isopropyl alcohol - water mixture (IPA-water) as developer to quickly define the microfluidic patterns. The prototyped devices were successfully bonded, sealed, and the device functionality tested and demonstrated. The screen printing based technique can produce microfluidic channels as small as 50 micrometers quite easily, making this technique the most cost-effective, fairly high precision and at the same time an ultra economical plastic microfluidic components fabrication process reported to date.

Development & Characterization of Multifunctional Microfluidic Materials

Science.gov (United States)

Ucar, Ahmet Burak

The field of microfluidics has been mostly investigated for miniaturized lab on a chip devices for analytical and clinical applications. However, there is an emerging class of "smart" microfluidic materials, combining microfluidics with soft polymers to yield new functionalities. The best inspiration for such materials found in nature is skin, whose functions are maintained and controlled by a vascular "microfluidic" network. We report here the development and characterization of a few new classes of microfluidic materials. First, we introduced microfluidic materials that can change their stiffness on demand. These materials were based on an engineered microchannel network embedded into a matrix of polydimethylsiloxane (PDMS), whose channels were filled with a liquid photoresist (SU- 8). The elastomer filled with the photoresist was initially soft. The materials were shaped into a desired geometry and then exposed to UV-light. Once photocured, the material preserved the defined shape and it could be bent, twisted or stretched with a very high recoverable strain. As soon as the external force was removed the material returned back to its predefined shape. Thus, the polymerized SU-8 acted as the 'endoskeleton' of the microfluidic network, which drastically increased the composite's elastic and bending moduli. Second, we demonstrated a class of simple and versatile soft microfluidic materials that can be turned optically transparent or colored on demand. These materials were made in the form of flexible sheets containing a microchannel network embedded in PDMS, similar to the photocurable materials. However, this time the channels were filled with a glycerolwater mixture, whose refractive index was matched with that of the PDMS matrix. By pumping such dye solutions into the channel network and consecutively replacing the medium, we showed that we can control the material's color and light transmittance in the visible and near-infrared regions, which can be used for

A "place n play" modular pump for portable microfluidic applications.

Science.gov (United States)

Li, Gang; Luo, Yahui; Chen, Qiang; Liao, Lingying; Zhao, Jianlong

2012-03-01

This paper presents an easy-to-use, power-free, and modular pump for portable microfluidic applications. The pump module is a degassed particle desorption polydimethylsiloxane (PDMS) slab with an integrated mesh-shaped chamber, which can be attached on the outlet port of microfluidic device to absorb the air in the microfluidic system and then to create a negative pressure for driving fluid. Different from the existing monolithic degassed PDMS pumps that are generally restricted to limited pumping capacity and are only compatible with PDMS-based microfluidic devices, this pump can offer various possible configures of pumping power by varying the geometries of the pump or by combining different pump modules and can also be employed in any material microfluidic devices. The key advantage of this pump is that its operation only requires the user to place the degassed PDMS slab on the outlet ports of microfluidic devices. To help design pumps with a suitable pumping performance, the effect of pump module geometry on its pumping capacity is also investigated. The results indicate that the performance of the degassed PDMS pump is strongly dependent on the surface area of the pump chamber, the exposure area and the volume of the PDMS pump slab. In addition, the initial volume of air in the closed microfluidic system and the cross-linking degree of PDMS also affect the performance of the degassed PDMS pump. Finally, we demonstrated the utility of this modular pumping method by applying it to a glass-based microfluidic device and a PDMS-based protein crystallization microfluidic device.

Isolation of cancer cells by "in situ" microfluidic biofunctionalization protocols

DEFF Research Database (Denmark)

De Vitis, Stefania; Matarise, Giuseppina; Pardeo, Francesca

2014-01-01

The aim of this work is the development of a microfluidic immunosensor for the immobilization of cancer cells and their separation from healthy cells by using "in situ" microfluidic biofunctionalization protocols. These protocols allow to link antibodies on microfluidic device surfaces and can be...

Advantages and challenges of microfluidic cell culture in polydimethylsiloxane devices.

Science.gov (United States)

Halldorsson, Skarphedinn; Lucumi, Edinson; Gómez-Sjöberg, Rafael; Fleming, Ronan M T

2015-01-15

Culture of cells using various microfluidic devices is becoming more common within experimental cell biology. At the same time, a technological radiation of microfluidic cell culture device designs is currently in progress. Ultimately, the utility of microfluidic cell culture will be determined by its capacity to permit new insights into cellular function. Especially insights that would otherwise be difficult or impossible to obtain with macroscopic cell culture in traditional polystyrene dishes, flasks or well-plates. Many decades of heuristic optimization have gone into perfecting conventional cell culture devices and protocols. In comparison, even for the most commonly used microfluidic cell culture devices, such as those fabricated from polydimethylsiloxane (PDMS), collective understanding of the differences in cellular behavior between microfluidic and macroscopic culture is still developing. Moving in vitro culture from macroscopic culture to PDMS based devices can come with unforeseen challenges. Changes in device material, surface coating, cell number per unit surface area or per unit media volume may all affect the outcome of otherwise standard protocols. In this review, we outline some of the advantages and challenges that may accompany a transition from macroscopic to microfluidic cell culture. We focus on decisive factors that distinguish macroscopic from microfluidic cell culture to encourage a reconsideration of how macroscopic cell culture principles might apply to microfluidic cell culture. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Separation followed by direct SERS detection of explosives on a novel black silicon multifunctional nanostructured surface prepared in a microfluidic channel

DEFF Research Database (Denmark)

Talian, Ivan; Hübner, Jörg

2013-01-01

The article describes the multifunctionality of a novel black silicon (BS) nanostructured surface covered with a thin layer of noble metal prepared in the a microfluidic channel. It is focused on the separation properties of the BS substrate with direct detection of the separated analytes utilizing...

A Microfluidic Approach for Studying Piezo Channels.

Science.gov (United States)

Maneshi, M M; Gottlieb, P A; Hua, S Z

2017-01-01

Microfluidics is an interdisciplinary field intersecting many areas in engineering. Utilizing a combination of physics, chemistry, biology, and biotechnology, along with practical applications for designing devices that use low volumes of fluids to achieve high-throughput screening, is a major goal in microfluidics. Microfluidic approaches allow the study of cells growth and differentiation using a variety of conditions including control of fluid flow that generates shear stress. Recently, Piezo1 channels were shown to respond to fluid shear stress and are crucial for vascular development. This channel is ideal for studying fluid shear stress applied to cells using microfluidic devices. We have developed an approach that allows us to analyze the role of Piezo channels on any given cell and serves as a high-throughput screen for drug discovery. We show that this approach can provide detailed information about the inhibitors of Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

Highly Stretchable and Transparent Microfluidic Strain Sensors for Monitoring Human Body Motions.

Science.gov (United States)

Yoon, Sun Geun; Koo, Hyung-Jun; Chang, Suk Tai

2015-12-16

We report a new class of simple microfluidic strain sensors with high stretchability, transparency, sensitivity, and long-term stability with no considerable hysteresis and a fast response to various deformations by combining the merits of microfluidic techniques and ionic liquids. The high optical transparency of the strain sensors was achieved by introducing refractive-index matched ionic liquids into microfluidic networks or channels embedded in an elastomeric matrix. The microfluidic strain sensors offer the outstanding sensor performance under a variety of deformations induced by stretching, bending, pressing, and twisting of the microfluidic strain sensors. The principle of our microfluidic strain sensor is explained by a theoretical model based on the elastic channel deformation. In order to demonstrate its capability of practical usage, the simple-structured microfluidic strain sensors were performed onto a finger, wrist, and arm. The highly stretchable and transparent microfluidic strain sensors were successfully applied as potential platforms for distinctively monitoring a wide range of human body motions in real time. Our novel microfluidic strain sensors show great promise for making future stretchable electronic devices.

Review of Recent Metamaterial Microfluidic Sensors.

Science.gov (United States)

Salim, Ahmed; Lim, Sungjoon

2018-01-15

Metamaterial elements/arrays exhibit a sensitive response to fluids yet with a small footprint, therefore, they have been an attractive choice to realize various sensing devices when integrated with microfluidic technology. Micro-channels made from inexpensive biocompatible materials avoid any contamination from environment and require only microliter-nanoliter sample for sensing. Simple design, easy fabrication process, light weight prototype, and instant measurements are advantages as compared to conventional (optical, electrochemical and biological) sensing systems. Inkjet-printed flexible sensors find their utilization in rapidly growing wearable electronics and health-monitoring flexible devices. Adequate sensitivity and repeatability of these low profile microfluidic sensors make them a potential candidate for point-of-care testing which novice patients can use reliably. Aside from degraded sensitivity and lack of selectivity in all practical microwave chemical sensors, they require an instrument, such as vector network analyzer for measurements and not readily available as a self-sustained portable sensor. This review article presents state-of-the-art metamaterial inspired microfluidic bio/chemical sensors (passive devices ranging from gigahertz to terahertz range) with an emphasis on metamaterial sensing circuit and microfluidic detection. We also highlight challenges and strategies to cope these issues which set future directions.

Microfluidic Biochip Design

Science.gov (United States)

Panzarella, Charles

2004-01-01

As humans prepare for the exploration of our solar system, there is a growing need for miniaturized medical and environmental diagnostic devices for use on spacecrafts, especially during long-duration space missions where size and power requirements are critical. In recent years, the biochip (or Lab-on-a- Chip) has emerged as a technology that might be able to satisfy this need. In generic terms, a biochip is a miniaturized microfluidic device analogous to the electronic microchip that ushered in the digital age. It consists of tiny microfluidic channels, pumps and valves that transport small amounts of sample fluids to biosensors that can perform a variety of tests on those fluids in near real time. It has the obvious advantages of being small, lightweight, requiring less sample fluids and reagents and being more sensitive and efficient than larger devices currently in use. Some of the desired space-based applications would be to provide smaller, more robust devices for analyzing blood, saliva and urine and for testing water and food supplies for the presence of harmful contaminants and microorganisms. Our group has undertaken the goal of adapting as well as improving upon current biochip technology for use in long-duration microgravity environments. In addition to developing computational models of the microfluidic channels, valves and pumps that form the basis of every biochip, we are also trying to identify potential problems that could arise in reduced gravity and develop solutions to these problems. One such problem is due to the prevalence of bubbly sample fluids in microgravity. A bubble trapped in a microfluidic channel could be detrimental to the operation of a biochip. Therefore, the process of bubble formation in microgravity needs to be studied, and a model of this process has been developed and used to understand how bubbles develop and move through biochip components. It is clear that some type of bubble filter would be necessary in Space, and

Advanced combinational microfluidic multiplexer for fuel cell reactors

International Nuclear Information System (INIS)

Lee, D W; Kim, Y; Cho, Y-H; Doh, I

2013-01-01

An advanced combinational microfluidic multiplexer capable to address multiple fluidic channels for fuel cell reactors is proposed. Using only 4 control lines and two different levels of control pressures, the proposed multiplexer addresses up to 19 fluidic channels, at least two times larger than the previous microfluidic multiplexers. The present multiplexer providing high control efficiency and simple structure for channel addressing would be used in the application areas of the integrated microfluidic systems such as fuel cell reactors and dynamic pressure generators

Digital microfluidic processing of mammalian embryos for vitrification.

Directory of Open Access Journals (Sweden)

Derek G Pyne

Full Text Available Cryopreservation is a key technology in biology and clinical practice. This paper presents a digital microfluidic device that automates sample preparation for mammalian embryo vitrification. Individual micro droplets manipulated on the microfluidic device were used as micro-vessels to transport a single mouse embryo through a complete vitrification procedure. Advantages of this approach, compared to manual operation and channel-based microfluidic vitrification, include automated operation, cryoprotectant concentration gradient generation, and feasibility of loading and retrieval of embryos.

Centrifugal microfluidic platforms: advanced unit operations and applications.

Science.gov (United States)

Strohmeier, O; Keller, M; Schwemmer, F; Zehnle, S; Mark, D; von Stetten, F; Zengerle, R; Paust, N

2015-10-07

Centrifugal microfluidics has evolved into a mature technology. Several major diagnostic companies either have products on the market or are currently evaluating centrifugal microfluidics for product development. The fields of application are widespread and include clinical chemistry, immunodiagnostics and protein analysis, cell handling, molecular diagnostics, as well as food, water, and soil analysis. Nevertheless, new fluidic functions and applications that expand the possibilities of centrifugal microfluidics are being introduced at a high pace. In this review, we first present an up-to-date comprehensive overview of centrifugal microfluidic unit operations. Then, we introduce the term "process chain" to review how these unit operations can be combined for the automation of laboratory workflows. Such aggregation of basic functionalities enables efficient fluidic design at a higher level of integration. Furthermore, we analyze how novel, ground-breaking unit operations may foster the integration of more complex applications. Among these are the storage of pneumatic energy to realize complex switching sequences or to pump liquids radially inward, as well as the complete pre-storage and release of reagents. In this context, centrifugal microfluidics provides major advantages over other microfluidic actuation principles: the pulse-free inertial liquid propulsion provided by centrifugal microfluidics allows for closed fluidic systems that are free of any interfaces to external pumps. Processed volumes are easily scalable from nanoliters to milliliters. Volume forces can be adjusted by rotation and thus, even for very small volumes, surface forces may easily be overcome in the centrifugal gravity field which enables the efficient separation of nanoliter volumes from channels, chambers or sensor matrixes as well as the removal of any disturbing bubbles. In summary, centrifugal microfluidics takes advantage of a comprehensive set of fluidic unit operations such as

Rapid Fabrication of Electrophoretic Microfluidic Devices from Polyester, Adhesives and Gold Leaf

Directory of Open Access Journals (Sweden)

Christopher Birch

2017-01-01

Full Text Available In the last decade, the microfluidic community has witnessed an evolution in fabrication methodologies that deviate from using conventional glass and polymer-based materials. A leading example within this group is the print, cut and laminate (PCL approach, which entails the laser cutting of microfluidic architecture into ink toner-laden polyester sheets, followed by the lamination of these layers for device assembly. Recent success when applying this method to human genetic fingerprinting has highlighted that it is now ripe for the refinements necessary to render it amenable to mass-manufacture. In this communication, we detail those modifications by identifying and implementing a suitable heat-sensitive adhesive (HSA material to equip the devices with the durability and resilience required for commercialization and fieldwork. Importantly, this augmentation is achieved without sacrificing any of the characteristics which make the PCL approach attractive for prototyping. Exemplary HSA-devices performed DNA extraction, amplification and separation which, when combined, constitute the complete sequence necessary for human profiling and other DNA-based analyses.

Living bacterial sacrificial porogens to engineer decellularized porous scaffolds.

Directory of Open Access Journals (Sweden)

Feng Xu

Full Text Available Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types.

A truly Lego®-like modular microfluidics platform

Science.gov (United States)

Vittayarukskul, Kevin; Lee, Abraham Phillip

2017-03-01

Ideally, a modular microfluidics platform should be simple to assemble and support 3D configurations for increased versatility. The modular building blocks should also be mass producible like electrical components. These are fundamental features of world-renowned Legos® and why Legos® inspire many existing modular microfluidics platforms. In this paper, a truly Lego®-like microfluidics platform is introduced, and its basic feasibility is demonstrated. Here, PDMS building blocks resembling 2  ×  2 Lego® bricks are cast from 3D-printed master molds. The blocks are pegged and stacked on a traditional Lego® plate to create simple, 3D microfluidic networks, such as a single basket weave. Characteristics of the platform, including reversible sealing and automatic alignment of channels, are also analyzed and discussed in detail.

A truly Lego®-like modular microfluidics platform

International Nuclear Information System (INIS)

Vittayarukskul, Kevin; Lee, Abraham Phillip

2017-01-01

Ideally, a modular microfluidics platform should be simple to assemble and support 3D configurations for increased versatility. The modular building blocks should also be mass producible like electrical components. These are fundamental features of world-renowned Legos ® and why Legos ® inspire many existing modular microfluidics platforms. In this paper, a truly Lego ® -like microfluidics platform is introduced, and its basic feasibility is demonstrated. Here, PDMS building blocks resembling 2  ×  2 Lego ® bricks are cast from 3D-printed master molds. The blocks are pegged and stacked on a traditional Lego ® plate to create simple, 3D microfluidic networks, such as a single basket weave. Characteristics of the platform, including reversible sealing and automatic alignment of channels, are also analyzed and discussed in detail. (paper)

Synthesis of Au nanotubes with SiOx nanowires as sacrificial templates

International Nuclear Information System (INIS)

Lu, M.Y.; Chang, Y.C.; Chen, L.J.

2006-01-01

Gold nanotubes with SiO x nanowires as sacrificial templates have been synthesized. SiO x nanowires were functionalized by 3-aminopropyl trimethoxysilane that generates a charged surface. The attachment of negatively charged Au nanoparticles was followed. The coverage of Au nanoparticles was initially less than 30%. Further coverage was achieved by the reduction of gold hydroxide to grow the continuous nanoshell on Au nanoparticles, which serve as nucleation sites. The final coverage of Au nanoshells on SiO x nanowires depends strongly on the relative amount of SiO x nanowires in gold hydroxide solution. Both transmission electron microscope and scanning electron microscope images revealed the formation of Au nanotubes with the removal of SiO x nanowires by etching in a dilute HF solution

‘Chip-olate’ and dry-film resists for efficient fabrication, singulation and sealing of microfluidic chips

International Nuclear Information System (INIS)

Temiz, Yuksel; Delamarche, Emmanuel

2014-01-01

This paper describes a technique for high-throughput fabrication and efficient singulation of chips having closed microfluidic structures and takes advantage of dry-film resists (DFRs) for efficient sealing of capillary systems. The technique is illustrated using 4-inch Si/SiO 2 wafers. Wafers carrying open microfluidic structures are partially diced to about half of their thickness. Treatments such as surface cleaning are done at wafer-level, then the structures are sealed using low-temperature (45 °C) lamination of a DFR that is pre-patterned using a craft cutter, and ready-to-use chips are finally separated manually like a chocolate bar by applying a small force (≤ 4 N). We further show that some DFRs have low auto-fluorescence at wavelengths typically used for common fluorescent dyes and that mechanical properties of some DFRs allow for the lamination of 200 μm wide microfluidic structures with negligible sagging (∼1 μm). The hydrophilicity (advancing contact angle of ∼60°) of the DFR supports autonomous capillary-driven flow without the need for additional surface treatment of the microfluidic chips. Flow rates from 1 to 5 µL min -1 are generated using different geometries of channels and capillary pumps. In addition, the ‘chip-olate’ technique is compatible with the patterning of capture antibodies on DFR for use in immunoassays. We believe this technique to be applicable to the fabrication of a wide range of microfluidic and lab-on-a-chip devices and to offer a viable alternative to many labor-intensive processes that are currently based on wafer bonding techniques or on the molding of poly(dimethylsiloxane) (PDMS) layers. (technical note)

Materials for microfluidic chip fabrication.

Science.gov (United States)

Ren, Kangning; Zhou, Jianhua; Wu, Hongkai

2013-11-19

Through manipulating fluids using microfabricated channel and chamber structures, microfluidics is a powerful tool to realize high sensitive, high speed, high throughput, and low cost analysis. In addition, the method can establish a well-controlled microenivroment for manipulating fluids and particles. It also has rapid growing implementations in both sophisticated chemical/biological analysis and low-cost point-of-care assays. Some unique phenomena emerge at the micrometer scale. For example, reactions are completed in a shorter amount of time as the travel distances of mass and heat are relatively small; the flows are usually laminar; and the capillary effect becomes dominant owing to large surface-to-volume ratios. In the meantime, the surface properties of the device material are greatly amplified, which can lead to either unique functions or problems that we would not encounter at the macroscale. Also, each material inherently corresponds with specific microfabrication strategies and certain native properties of the device. Therefore, the material for making the device plays a dominating role in microfluidic technologies. In this Account, we address the evolution of materials used for fabricating microfluidic chips, and discuss the application-oriented pros and cons of different materials. This Account generally follows the order of the materials introduced to microfluidics. Glass and silicon, the first generation microfluidic device materials, are perfect for capillary electrophoresis and solvent-involved applications but expensive for microfabriaction. Elastomers enable low-cost rapid prototyping and high density integration of valves on chip, allowing complicated and parallel fluid manipulation and in-channel cell culture. Plastics, as competitive alternatives to elastomers, are also rapid and inexpensive to microfabricate. Their broad variety provides flexible choices for different needs. For example, some thermosets support in-situ fabrication of

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

OpenAIRE

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 oppor...

Aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance

International Nuclear Information System (INIS)

Imaizumi, S.; Mikami, K.; Yamada, K.

1980-01-01

An aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance, which consists essentially of, in weight percentage: zinc - 0.3 to 3.0%, magnesium - 0.2 to 4.0%, manganese - 0.3 to 2.0%, and, the balance aluminum and incidental impurities; said alloy including an aluminum alloy also containing at least one element selected from the group consisting of, in weight percentage: indium - 0.005 to 0.2%, tin - 0.01 to 0.3%, and, bismuth - 0.01 to 0.3%; provided that the total content of indium, tin and bismuth being up to 0.3%

Optical manipulation with two beam traps in microfluidic polymer systems

DEFF Research Database (Denmark)

Khoury Arvelo, Maria; Matteucci, Marco; Sørensen, Kristian Tølbøl

2015-01-01

An optical trapping system with two opposing laser beams, also known as the optical stretcher, are naturally constructed inside a microfluidic lab-on-chip system. We present and compare two approaches to combine a simple microfluidic system with either waveguides directly written in the microflui......An optical trapping system with two opposing laser beams, also known as the optical stretcher, are naturally constructed inside a microfluidic lab-on-chip system. We present and compare two approaches to combine a simple microfluidic system with either waveguides directly written...

Sacrificial hydrogen generation from aqueous triethanolamine with Eosin Y-sensitized Pt/TiO2 photocatalyst in UV, visible and solar light irradiation.

Science.gov (United States)

Chowdhury, Pankaj; Gomaa, Hassan; Ray, Ajay K

2015-02-01

In this paper, we have studied Eosin Y-sensitized sacrificial hydrogen generation with triethanolamine as electron donor in UV, visible, and solar light irradiation. Aeroxide TiO2 was loaded with platinum metal via solar photo-deposition method to reduce the electron hole recombination process. Photocatalytic sacrificial hydrogen generation was influenced by several factors such as platinum loading (wt%) on TiO2, solution pH, Eosin Y to Pt/TiO2 mass ratio, triethanolamine concentration, and light (UV, visible and solar) intensities. Detailed reaction mechanisms in visible and solar light irradiation were established. Oxidation of triethanolamine and formaldehyde formation was correlated with hydrogen generation in both visible and solar lights. Hydrogen generation kinetics followed a Langmuir-type isotherm with reaction rate constant and adsorption constant of 6.77×10(-6) mol min(-1) and 14.45 M(-1), respectively. Sacrificial hydrogen generation and charge recombination processes were studied as a function of light intensities. Apparent quantum yields (QYs) were compared for UV, visible, and solar light at four different light intensities. Highest QYs were attained at lower light intensity because of trivial charge recombination. At 30 mW cm(-2) we achieved QYs of 10.82%, 12.23% and 11.33% in UV, visible and solar light respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Downstream bioprocess characterisation within microfluidic devices

DEFF Research Database (Denmark)

Marques, Marco; Krühne, Ulrich; Szita, Nicolas

2016-01-01

developed which has, to some extent, hindered their implementation as early process development tools. Microfluidic devices are particularly attractive for using fewer resources, for having the possibility of parallelisation and for requiring fewer mechanical manipulations. The expectation...... is that these devices will facilitate the rapid definition of critical process parameters, and thus ultimately reduce production costs. We have developed several microfluidic mDUOs and combined them with advanced and novel analytical approaches, resulting in devices that can potentially be employed for both analytical...... for the liquid–liquid extraction of pharmaceuticals, for the purification and concentration of drug delivery vehicles, and for the flocculation of yeast cells in microfluidic devices. For the latter, we will present for the first time the capability to study flocculation-growth independent from the floc breakage...

A centrifugal microfluidic platform for point-of-care diagnostic applications

Directory of Open Access Journals (Sweden)

Suzanne Hugo

2014-02-01

Full Text Available Microfluidic systems enable precise control over tiny volumes of fluid in a compact and low-cost form, thus providing the ideal platform on which to develop point-of-care diagnostic solutions. Centrifugal microfluidic systems, also referred to as lab-on-a-disc or lab-on-a-CD systems, provide a particularly attractive solution for the implementation of microfluidic point-of-care diagnostic solutions as a result of their simple and compact instrumentation, as well as their functional diversity. Here we detail the implementation of a centrifugal microfluidic platform the first of its kind in South Africa as a foundation for the development of point-of-care diagnostic applications for which both the need and impact is great. The centrifugal microfluidic platform consists of three main components: a microfluidic disc device similar in size and shape to a CD, a system for controlling fluid flow on the device, and a system for recording the results obtained. These components have been successfully implemented and tested. Preliminary test results show that microfluidic functions such as pumping and valving of fluids can be successfully achieved, as well as the generation of monodisperse microfluidic droplets, providing a complete centrifugal microfluidic platform and the building blocks on which to develop a variety of applications, including point-of-care diagnostics. The lab-on-a-disc platform has the potential to provide new diagnostic solutions at the point-of-need in health- and industry-related areas. This paves the way for providing resource limited areas with services such as improved, decentralised health-care access or water-quality monitoring, and reduced diagnosis times at a low cost.

CO2-laser micromachining and back-end processing for rapid production of PMMA-based microfluidic systems

DEFF Research Database (Denmark)

Klank, Henning; Kutter, Jörg Peter; Geschke, Oliver

2002-01-01

, a three-layer polymer microstructure with included optical fibers was fabricated within two days. The use of CO2-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 this article, we focus on the enormous potential of a CO2-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...... 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...

Method for generating small and ultra small apertures, slits, nozzles and orifices

Science.gov (United States)

Khounsary, Ali M [Hinsdale, IL

2012-05-22

A method and device for one or more small apertures, slits, nozzles and orifices, preferably having a high aspect ratio. In one embodiment, one or more alternating layers of sacrificial layers and blocking layers are deposited onto a substrate. Each sacrificial layer is made of a material which preferably allows a radiation to substantially pass through. Each blocking layer is made of a material which substantially blocks the radiation.

Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

Science.gov (United States)

Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

2015-01-01

This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

Redundancy Optimization for Error Recovery in Digital Microfluidic Biochips

DEFF Research Database (Denmark)

Alistar, Mirela; Pop, Paul; Madsen, Jan

2015-01-01

Microfluidic-based biochips are replacing the conventional biochemical analyzers, and are able to integrate all the necessary functions for biochemical analysis. The digital microfluidic biochips are based on the manipulation of liquids not as a continuous flow, but as discrete droplets. Research......Microfluidic-based biochips are replacing the conventional biochemical analyzers, and are able to integrate all the necessary functions for biochemical analysis. The digital microfluidic biochips are based on the manipulation of liquids not as a continuous flow, but as discrete droplets....... Researchers have proposed approaches for the synthesis of digital microfluidic biochips, which, starting from a biochemical application and a given biochip architecture, determine the allocation, resource binding, scheduling, placement and routing of the operations in the application. During the execution...... propose an online recovery strategy, which decides during the execution of the biochemical application the introduction of the redundancy required for fault-tolerance. We consider both time redundancy, i.e., re-executing erroneous operations, and space redundancy, i.e., creating redundant droplets...

Neighboring Hetero-Atom Assistance of Sacrificial Amines to Hydrogen Evolution Using Pt-Loaded TiO2-Photocatalyst

Directory of Open Access Journals (Sweden)

Masahide Yasuda

2014-05-01

Full Text Available Photocatalytic H2 evolution was examined using Pt-loaded TiO2-photocatalyst in the presence of amines as sacrificial agents. In the case of amines with all of the carbon attached to the hetero-atom such as 2-aminoethanol, 1,2-diamonoethane, 2-amino-1,3-propanediol, and 3-amino-1,2-propanediol, they were completely decomposed into CO2 and water to quantitatively evolve H2. On the other hand, the amines with both hetero-atoms and one methyl group at the β-positions (neighboring carbons of amino group such as 2-amino-1-propanol and 1,2-diaminopropane were partially decomposed. Also, the photocatalytic H2 evolution using amines without the hetero-atoms at the β-positions such as ethylamine, propylamine, 1-butylamine, 1,3-diaminopropane, 2-propylamine, and 2-butylamine was inefficient. Thus, it was found that the neighboring hetero-atom strongly assisted the degradation of sacrificial amines. Moreover, rate constants for H2 evolution were compared among amines. In conclusion, the neighboring hetero-atom did not affect the rate constants but enhanced the yield of hydrogen evolution.

Printed wax masks for 254 nm deep-UV pattering of PMMA-based microfluidics

International Nuclear Information System (INIS)

Fan, Yiqiang; Liu, Yang; Li, Huawei; Foulds, Ian G

2012-01-01

This paper reports a new technique for masking deep-UV exposure of poly(methyl methacrylate) (PMMA) using a printed wax mask. This technique provides an inexpensive and bulk fabrication method for PMMA structures. The technique involves the direct printing of the mask onto a polymer sheet using a commercial wax printer. The wax layer was then transferred to a PMMA substrate using a thermal laminator, exposed using deep-UV (with a wavelength of 254 nm), developed in an IPA:water solution, and completed by bonding on a PMMA cap layer. A sample microfluidic device fabricated with this method is also presented, with the microchannel as narrow as 50 µm. The whole process is easy to perform without the requirement for any microfabrication facilities. (technical note)

Microfluidic Devices for Forensic DNA Analysis: A Review.

Science.gov (United States)

Bruijns, Brigitte; van Asten, Arian; Tiggelaar, Roald; Gardeniers, Han

2016-08-05

Microfluidic devices may offer various advantages for forensic DNA analysis, such as reduced risk of contamination, shorter analysis time and direct application at the crime scene. Microfluidic chip technology has already proven to be functional and effective within medical applications, such as for point-of-care use. In the forensic field, one may expect microfluidic technology to become particularly relevant for the analysis of biological traces containing human DNA. This would require a number of consecutive steps, including sample work up, DNA amplification and detection, as well as secure storage of the sample. This article provides an extensive overview of microfluidic devices for cell lysis, DNA extraction and purification, DNA amplification and detection and analysis techniques for DNA. Topics to be discussed are polymerase chain reaction (PCR) on-chip, digital PCR (dPCR), isothermal amplification on-chip, chip materials, integrated devices and commercially available techniques. A critical overview of the opportunities and challenges of the use of chips is discussed, and developments made in forensic DNA analysis over the past 10-20 years with microfluidic systems are described. Areas in which further research is needed are indicated in a future outlook.

In search of low cost biological analysis: Wax or acrylic glue bonded paper microfluidic devices

KAUST Repository

Kodzius, Rimantas; Gong, Xiuqing; Li, Shunbo; Qin, Jianhua; Wen, Weijia; Wu, Jinbo; Xiao, Kang; Yi, Xin

2011-01-01

We report a simple, low-cost and detachable microfluidic chip incorporating easily accessible paper, glass slides or other polymer films as the chip materials along with adhesive wax or cyanoacrylate-based resin as the recycling bonding material. We use a laser to cut through the paper or film to form patterns and then sandwich the paper and film between glass sheets or polymer membranes. The hot-melt adhesive wax or simple cyanoacrylate-based resin can realize bridge bonding between various materials, for example, paper, polymethylmethacrylate film, glass sheets, or metal plate. The wax bonding process is reversible and the wax is reusable through a melting and cooling process. With this process, a three-dimensional (3D) microfluidic chip is achievable by evacuating the channels of adhesive material in a hot-water. We applied the wax-paper based microfluidic chip to HeLa cell electroporation. Subsequently, a prototype of a 5-layer 3D chip was fabricated by multilayer wax bonding. To check the sealing ability and the durability of the chip, green fluorescence protein recombinant E. coli bacteria were cultured, with which the chemotaxis of E. coli was studied in order to determine the influence of antibiotic ciprofloxacin concentration on the E. coli migration. The chip bonded with cyanoacrylate-based resin was tested by measuring protein concentration and carrying out DNA capillary electrophoresis. To study the biocompatibility and applicability of our microfluidic chip fabrication technology, we tested the PCR compatibility of our chip materials along with various other common materials employed in the fabrication of microfluidic chips including: silicon, several kinds of silicon oxide, glasses, plastics, wax, and adhesives, etc. Two-temperature PCR was performed with these materials to determine their PCR-inhibitory effect. In most of the cases, addition of bovine serum albumin effectively improved the reaction yield. We also studied the individual PCR components

Biomarker detection for disease diagnosis using cost-effective microfluidic platforms.

Science.gov (United States)

Sanjay, Sharma T; Fu, Guanglei; Dou, Maowei; Xu, Feng; Liu, Rutao; Qi, Hao; Li, XiuJun

2015-11-07

Early and timely detection of disease biomarkers can prevent the spread of infectious diseases, and drastically decrease the death rate of people suffering from different diseases such as cancer and infectious diseases. Because conventional diagnostic methods have limited application in low-resource settings due to the use of bulky and expensive instrumentation, simple and low-cost point-of-care diagnostic devices for timely and early biomarker diagnosis is the need of the hour, especially in rural areas and developing nations. The microfluidics technology possesses remarkable features for simple, low-cost, and rapid disease diagnosis. There have been significant advances in the development of microfluidic platforms for biomarker detection of diseases. This article reviews recent advances in biomarker detection using cost-effective microfluidic devices for disease diagnosis, with the emphasis on infectious disease and cancer diagnosis in low-resource settings. This review first introduces different microfluidic platforms (e.g. polymer and paper-based microfluidics) used for disease diagnosis, with a brief description of their common fabrication techniques. Then, it highlights various detection strategies for disease biomarker detection using microfluidic platforms, including colorimetric, fluorescence, chemiluminescence, electrochemiluminescence (ECL), and electrochemical detection. Finally, it discusses the current limitations of microfluidic devices for disease biomarker detection and future prospects.

CMOS Enabled Microfluidic Systems for Healthcare Based Applications

KAUST Repository

Khan, Sherjeel M.; Gumus, Abdurrahman; Nassar, Joanna M.; Hussain, Muhammad Mustafa

2018-01-01

With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people-process-data-device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen.

CMOS Enabled Microfluidic Systems for Healthcare Based Applications

KAUST Repository

Khan, Sherjeel M.

2018-02-27

With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people-process-data-device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen.

Formation of a vertical MOSFET for charge sensing in a Si micro-fluidic channel

International Nuclear Information System (INIS)

Lyu, Hong-Kun; Kim, Dong-Sun; Shin, Jang-Kyoo; Choi, Pyung; Lee, Jong-Hyun; Park, Hey-Jung; Park, Chin-Sung; Lim, Geun-Bae

2004-01-01

We have formed a fluidic channel that can be used in micro-fluidic systems and fabricated a 3-dimensional vertical metal-oxide semiconductor field-effect transistor (vertical MOSFET) in the convex corner of a Si micro-fluidic channel by using an anisotropic tetramethyl ammonium hydroxide (TMAH) etching solution. A Au/Cr layer was used for the gate metal and might be useful for detecting charged biomolecules. The electrical characteristics of the vertical MOSFET and its operation as a chemical sensor were investigated. At V DS = -5 V and V GS = -5 V the drain current of the device was -22.5 μA and the threshold voltage was about -1.4 V. A non-planar, non-rectangular vertical MOSFET with a trapezoidal gate was transformed into an equivalent rectangularly based one by using a Schwartz-Christoffel transformation. The LEVEL1 device parameters of the vertical MOSFET were extracted from the measured electrical device characteristics and were used in the SPICE simulation for the vertical MOSFET. The measured and the simulated results for the vertical PMOSFET showed relatively good agreement. When the vertical MOSFET was dipped into a thiol DNA solution, the drain current decreased due to charged biomolecules probably being adsorbed on the gate, which indicates that a vertical MOSFET in a Si micro-fluidic channel might be useful for sensing charged biomolecules.

In situ microfluidic dialysis for biological small-angle X-ray scattering

DEFF Research Database (Denmark)

Skou, Magda; Skou, Soren; Jensen, Thomas Glasdam

2014-01-01

Owing to the demand for low sample consumption and automated sample changing capabilities at synchrotron small-angle X-ray (solution) scattering (SAXS) beamlines, X-ray microfluidics is receiving continuously increasing attention. Here, a remote-controlled microfluidic device is presented for sim...... in incidental sample purification. Hence, this versatile microfluidic device enables investigation of experimentally induced structural changes under dynamically controllable sample conditions. (C) 2014 International Union of Crystallography......Owing to the demand for low sample consumption and automated sample changing capabilities at synchrotron small-angle X-ray (solution) scattering (SAXS) beamlines, X-ray microfluidics is receiving continuously increasing attention. Here, a remote-controlled microfluidic device is presented...

Microfluidic Devices for Drug Delivery Systems and Drug Screening

Science.gov (United States)

Kompella, Uday B.; Damiati, Safa A.

2018-01-01

Microfluidic devices present unique advantages for the development of efficient drug carrier particles, cell-free protein synthesis systems, and rapid techniques for direct drug screening. Compared to bulk methods, by efficiently controlling the geometries of the fabricated chip and the flow rates of multiphase fluids, microfluidic technology enables the generation of highly stable, uniform, monodispersed particles with higher encapsulation efficiency. Since the existing preclinical models are inefficient drug screens for predicting clinical outcomes, microfluidic platforms might offer a more rapid and cost-effective alternative. Compared to 2D cell culture systems and in vivo animal models, microfluidic 3D platforms mimic the in vivo cell systems in a simple, inexpensive manner, which allows high throughput and multiplexed drug screening at the cell, organ, and whole-body levels. In this review, the generation of appropriate drug or gene carriers including different particle types using different configurations of microfluidic devices is highlighted. Additionally, this paper discusses the emergence of fabricated microfluidic cell-free protein synthesis systems for potential use at point of care as well as cell-, organ-, and human-on-a-chip models as smart, sensitive, and reproducible platforms, allowing the investigation of the effects of drugs under conditions imitating the biological system. PMID:29462948

The Microfluidic Jukebox

Science.gov (United States)

Tan, Say Hwa; Maes, Florine; Semin, Benoît; Vrignon, Jérémy; Baret, Jean-Christophe

2014-04-01

Music is a form of art interweaving people of all walks of life. Through subtle changes in frequencies, a succession of musical notes forms a melody which is capable of mesmerizing the minds of people. With the advances in technology, we are now able to generate music electronically without relying solely on physical instruments. Here, we demonstrate a musical interpretation of droplet-based microfluidics as a form of novel electronic musical instruments. Using the interplay of electric field and hydrodynamics in microfluidic devices, well controlled frequency patterns corresponding to musical tracks are generated in real time. This high-speed modulation of droplet frequency (and therefore of droplet sizes) may also provide solutions that reconciles high-throughput droplet production and the control of individual droplet at production which is needed for many biochemical or material synthesis applications.

Review of Recent Metamaterial Microfluidic Sensors

Directory of Open Access Journals (Sweden)

Ahmed Salim

2018-01-01

Full Text Available Metamaterial elements/arrays exhibit a sensitive response to fluids yet with a small footprint, therefore, they have been an attractive choice to realize various sensing devices when integrated with microfluidic technology. Micro-channels made from inexpensive biocompatible materials avoid any contamination from environment and require only microliter–nanoliter sample for sensing. Simple design, easy fabrication process, light weight prototype, and instant measurements are advantages as compared to conventional (optical, electrochemical and biological sensing systems. Inkjet-printed flexible sensors find their utilization in rapidly growing wearable electronics and health-monitoring flexible devices. Adequate sensitivity and repeatability of these low profile microfluidic sensors make them a potential candidate for point-of-care testing which novice patients can use reliably. Aside from degraded sensitivity and lack of selectivity in all practical microwave chemical sensors, they require an instrument, such as vector network analyzer for measurements and not readily available as a self-sustained portable sensor. This review article presents state-of-the-art metamaterial inspired microfluidic bio/chemical sensors (passive devices ranging from gigahertz to terahertz range with an emphasis on metamaterial sensing circuit and microfluidic detection. We also highlight challenges and strategies to cope these issues which set future directions.

Temperature Sensing in Modular Microfluidic Architectures

Directory of Open Access Journals (Sweden)

Krisna C. Bhargava

2016-01-01

Full Text Available A discrete microfluidic element with integrated thermal sensor was fabricated and demonstrated as an effective probe for process monitoring and prototyping. Elements were constructed using stereolithography and market-available glass-bodied thermistors within the modular, standardized framework of previous discrete microfluidic elements demonstrated in the literature. Flow rate-dependent response due to sensor self-heating and microchannel heating and cooling was characterized and shown to be linear in typical laboratory conditions. An acid-base neutralization reaction was performed in a continuous flow setting to demonstrate applicability in process management: the ratio of solution flow rates was varied to locate the equivalence point in a titration, closely matching expected results. This element potentially enables complex, three-dimensional microfluidic architectures with real-time temperature feedback and flow rate sensing, without application specificity or restriction to planar channel routing formats.

‘Utilitarian’ judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good

OpenAIRE

Kahane, Guy; Everett, Jim A.C.; Earp, Brian D.; Farias, Miguel; Savulescu, Julian

2015-01-01

A growing body of research has focused on so-called ?utilitarian? judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such ?utilitarian? judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between ?utilitarian? judgment in such sacrificial dilemmas and a range of traits, attitudes,...

Patterned immobilization of antibodies within roll-to-roll hot embossed polymeric microfluidic channels.

Directory of Open Access Journals (Sweden)

Belachew Feyssa

Full Text Available This paper describes a method for the patterned immobilization of capture antibodies into a microfluidic platform fabricated by roll-to-roll (R2R hot embossing on poly (methyl methacrylate (PMMA. Covalent attachment of antibodies was achieved by two sequential inkjet printing steps. First, a polyethyleneimine (PEI layer was deposited onto oxygen plasma activated PMMA foil and further cross-linked with glutaraldehyde (GA to provide an amine-reactive aldehyde surface (PEI-GA. This step was followed by a second deposition of antibody by overprinting on the PEI-GA patterned PMMA foil. The PEI polymer ink was first formulated to ensure stable drop formation in inkjet printing and the printed films were characterized using atomic force microscopy (AFM and X-ray photoelectron spectroscopy (XPS. Anti-CRP antibody was patterned on PMMA foil by the developed method and bonded permanently with R2R hot embossed PMMA microchannels by solvent bonding lamination. The functionality of the immobilized antibody inside the microfluidic channel was evaluated by fluorescence-based sandwich immunoassay for detection of C-reactive protein (CRP. The antibody-antigen assay exhibited a good level of linearity over the range of 10 ng/ml to 500 ng/ml (R(2 = 0.991 with a calculated detection limit of 5.2 ng/ml. The developed patterning method is straightforward, rapid and provides a versatile approach for creating multiple protein patterns in a single microfluidic channel for multiplexed immunoassays.

Molecular Weiss domain polarization in piezoceramics to diaphragm, cantilever and channel construction in low-temperature-cofired ceramics for micro-fluidic applications

International Nuclear Information System (INIS)

Khanna, P.K.; Ahmad, S.; Grimme, R.

2005-01-01

This paper presents the efforts made to study the process of comminution to Weiss domain polarization and phase transition in piezoceramics together with the versatility of low-temperature-cofired ceramics-based devices and components for their ready adoption for typical applications in the area of micro-fluidics. A conceptual micro-fluidic module has been presented and few unit entities necessary for its realization have been described. The purpose of these entities is to position the sensors and actuators by using piezoelectric materials. Investigations are performed to make useful constructions like diaphragms and cantilevers for laying the sensing elements, cavities for burying the electronic chip devices, and channels for fluid transportation. In order to realize these constructions, the basic step involves machining of circular, straight line, rectangular and square-shaped structure in the green ceramic tapes followed by lamination and firing with post-machining in some cases. The diaphragm and cavity includes one or more un-machined layer stacked together with several machined layers with rectangular or square slits. The cantilever is an extension of the diaphragm creation process with inclusion of a post-machining step. The channel essentially consists of a machined green ceramic layer sandwiched between an un-machined and a partially machined layer. The fabrication for all the above constructions has been exemplified and the details have been discussed

Characterizations of gas purge valves for liquid alignment and gas removal in a microfluidic chip

International Nuclear Information System (INIS)

Chuang, Han-Sheng; Thakur, Raviraj; Wereley, Steven T

2012-01-01

Two polydimethylsiloxane (PDMS) gas purge valves for excessive gas removal in general lab-on-a-chip applications are presented in this paper. Both valves are devised based on a three-layer configuration comprising a top layer for liquid channels, a membrane and a bottom layer for gas channels. The pneumatic valves work as a normal gateway for fluids when the membrane is bulged down (open state) by vacuum or pushed up (closed state) by pressure. In the closed state, the air in front of a liquid can be removed through a small notch or a permeable PDMS membrane by compressing the liquid. The purge valve with a small notch across its valve seat, termed surface-tension (ST) valve, can be operated with pressure under 11.5 kPa. The liquid is mainly retained by the surface tension resulting from the hydrophobic channel walls. In contrast, the purge valve with vacuum-filled grooves adjacent to a liquid channel, termed gas-permeation (GP) valve, can be operated at pressure above 5.5 kPa. Based on the principle of gas permeation, the excessive air can be slowly removed through the vent grooves. Detailed evaluations of both valves in a pneumatically driven microfluidic chip were conducted. Specifically, the purge valves enable users to remove gas and passively align liquids at desired locations without using sensing devices or feedback circuits. Finally, a rapid mixing reaction was successfully performed with the GP valves, showing their practicability as incorporated in a microfluidic chip. (paper)

Optimized fabrication protocols of microfluidic devices for X-ray analysis

KAUST Repository

Catalano, Rossella

2014-07-01

Microfluidics combined with X-ray scattering techniques allows probing conformational changes or assembly processes of biological materials. Our aim was to develop a highly X-ray transparent microfluidic cell for detecting small variations of X-ray scattering involved in such processes. We describe the fabrication of a polyimide microfluidic device based on a simple, reliable and inexpensive lamination process. The implemented microstructured features result in windows with optimized X-ray transmission. The microfluidic device was characterized by X-ray microbeam scattering at the ID13 beamline of the European Synchrotron Radiation Facility. © 2014 Elsevier B.V. All rights reserved.

Investigation of endothelial growth using a sensors-integrated microfluidic system to simulate physiological barriers

Directory of Open Access Journals (Sweden)

Rajabi Taleieh

2015-09-01

Full Text Available In this paper we present a microfluidic system based on transparent biocompatible polymers with a porous membrane as substrate for various cell types which allows the simulation of various physiological barriers under continuous laminar flow conditions at distinct tunable shear rates. Besides live cell and fluorescence microscopy, integrated electrodes enable the investigation of the permeability and barrier function of the cell layer as well as their interaction with external manipulations using the Electric Cell-substrate Impedance Sensing (ECIS method.

Microfluidic Devices for Blood Fractionation

Directory of Open Access Journals (Sweden)

Chwee Teck Lim

2011-07-01

Full Text Available Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and biological research. Yet, processing blood is not trivial. In the past decade, a flurry of new microfluidic based technologies has emerged to address this compelling problem. Microfluidics is an attractive solution for this application leveraging its numerous advantages to process clinical blood samples. This paper reviews the various microfluidic approaches realized to successfully fractionate one or more blood components. Techniques to separate plasma from hematologic cellular components as well as isolating blood cells of interest including certain rare cells are discussed. Comparisons based on common separation metrics including efficiency (sensitivity, purity (selectivity, and throughput will be presented. Finally, we will provide insights into the challenges associated with blood-based separation systems towards realizing true point-of-care (POC devices and provide future perspectives.

Accelerated Biofluid Filling in Complex Microfluidic Networks by Vacuum-Pressure Accelerated Movement (V-PAM).

Science.gov (United States)

Yu, Zeta Tak For; Cheung, Mei Ki; Liu, Shirley Xiaosu; Fu, Jianping

2016-09-01

Rapid fluid transport and exchange are critical operations involved in many microfluidic applications. However, conventional mechanisms used for driving fluid transport in microfluidics, such as micropumping and high pressure, can be inaccurate and difficult for implementation for integrated microfluidics containing control components and closed compartments. Here, a technology has been developed termed Vacuum-Pressure Accelerated Movement (V-PAM) capable of significantly enhancing biofluid transport in complex microfluidic environments containing dead-end channels and closed chambers. Operation of the V-PAM entails a pressurized fluid loading into microfluidic channels where gas confined inside can rapidly be dissipated through permeation through a thin, gas-permeable membrane sandwiched between microfluidic channels and a network of vacuum channels. Effects of different structural and operational parameters of the V-PAM for promoting fluid filling in microfluidic environments have been studied systematically. This work further demonstrates the applicability of V-PAM for rapid filling of temperature-sensitive hydrogels and unprocessed whole blood into complex irregular microfluidic networks such as microfluidic leaf venation patterns and blood circulatory systems. Together, the V-PAM technology provides a promising generic microfluidic tool for advanced fluid control and transport in integrated microfluidics for different microfluidic diagnosis, organs-on-chips, and biomimetic studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inhibitory effect of common microfluidic materials on PCR outcome

KAUST Repository

Kodzius, Rimantas; Xiao, Kang; Wu, Jinbo; Yi, Xin; Gong, Xiuqing; Foulds, Ian G.; Wen, Weijia

2012-01-01

Microfluidic chips have a variety of applications in the biological sciences and medicine. In contrast with traditional experimental approaches, microfluidics entails lower sample and reagent consumption, allows faster reactions and enables

Implementation of Synchronous Micromotor in Developing Integrated Microfluidic Systems

Directory of Open Access Journals (Sweden)

Ala'aldeen Al-Halhouli

2014-07-01

Full Text Available This paper introduces the synchronous micromotor concept and presents new investigations on its application as an integrated driving mechanism in microfluidic systems. A spiral channel viscous micropump and a microstirrer are considered and tested as examples to verify the concept. The fabrication technology of such integrated systems is based on UV depth lithography, electroplating and soft lithography. The synchronous micromotor consists of a stator including double layer coils, and a rotor disk containing alternate permanent magnets. The coils are distributed evenly around the stator and arranged in three phases. The phases are excited by sinusoidal currents with a corresponding phase shift resulting in a rotating magnetic field. Regarding the spiral channel viscous micropump, a spiral disk was fixed onto the rotor disk and run at different rotational speeds. Tests showed very promising results, with a flow rate up to 1023 µL·min−1 at a motor rotational speed of 4500 rpm. Furthermore, for the application of a microstirred-tank bioreactor, the rotor disk design was modified to work as a stirrer. The performance of the developed microbioreactor was tested over a time period of approximately 10 h under constant stirring. Tests demonstrated the successful cultivation of S. cerevisiae through the integration of the microstirrer in a microbioreactor system. These systems prove that synchronous micromotors are well suited to serve as integrated driving mechanisms of active microfluidic components.

Optial sensing systems for microfluidic devices: a review

NARCIS (Netherlands)

Kuswandi, Bambang; Nuriman, [Unknown; Huskens, Jurriaan; Verboom, Willem

2007-01-01

This review deals with the application of optical sensing systems for microfluidic devices. In the “off-chip approach” macro-scale optical infrastructure is coupled, while the “on-chip approach” comprises the integration of micro-optical functions into microfluidic devices. The current progress of

Electric field-decoupled electroosmotic pump for microfluidic devices.

Science.gov (United States)

Liu, Shaorong; Pu, Qiaosheng; Lu, Joann J

2003-09-26

An electric field-free electroosmotic pump has been constructed and its pumping rate has been measured under various experimental conditions. The key component of the pump is an ion-exchange membrane grounding joint that serves two major functions: (i) to maintain fluid continuity between pump channels and microfluidic conduit and (ii) to ground the solution in the microfluidic channel at the joint through an external electrode, and hence to decouple the electric field applied to the pump channels from the rest of the microfluidic system. A theoretical model has been developed to calculate the pumping rates and its validity has been demonstrated.

Microfluidic production of polymeric functional microparticles

Science.gov (United States)

Jiang, Kunqiang

This dissertation focuses on applying droplet-based microfluidics to fabricate new classes of polymeric microparticles with customized properties for various applications. The integration of microfluidic techniques with microparticle engineering allows for unprecedented control over particle size, shape, and functional properties. Specifically, three types of microparticles are discussed here: (1) Magnetic and fluorescent chitosan hydrogel microparticles and their in-situ assembly into higher-order microstructures; (2) Polydimethylsiloxane (PDMS) microbeads with phosphorescent properties for oxygen sensing; (3) Macroporous microparticles as biological immunosensors. First, we describe a microfluidic approach to generate monodisperse chitosan hydrogel microparticles that can be further connected in-situ into higher-order microstructures. Microparticles of the biopolymer chitosan are created continuously by contacting an aqueous solution of chitosan at a microfluidic T-junction with a stream of hexadecane containing a nonionic detergent, followed by downstream crosslinking of the generated droplets by a ternary flow of glutaraldehyde. Functional properties of the microparticles can be easily varied by introducing payloads such as magnetic nanoparticles and/or fluorescent dyes into the chitosan solution. We then use these prepared microparticles as "building blocks" and assemble them into high ordered microstructures, i.e. microchains with controlled geometry and flexibility. Next, we describe a new approach to produce monodisperse microbeads of PDMS using microfluidics. Using a flow-focusing configuration, a PDMS precursor solution is dispersed into microdroplets within an aqueous continuous phase. These droplets are collected and thermally cured off-chip into soft, solid microbeads. In addition, our technique allows for direct integration of payloads, such as an oxygen-sensitive porphyrin dye, into the PDMS microbeads. We then show that the resulting dye

A PEG-DA microfluidic device for chemotaxis studies

International Nuclear Information System (INIS)

Traore, Mahama Aziz; Behkam, Bahareh

2013-01-01

The study of cells in a well-defined and chemically programmable microenvironment is essential for a complete and fundamental understanding of the cell behaviors with respect to specific chemical compounds. Flow-free microfluidic devices that generate quasi-steady chemical gradients (spatially varying but temporally constant) have been demonstrated as effective chemotaxis assay platforms due to dissociating the effect of chemical cues from mechanical shear forces caused by fluid flow. In this work, we demonstrate the fabrication and characterization of a flow-free microfluidic platform made of polyethylene glycol diacrylate (PEG-DA) hydrogel. We have demonstrated that the mass transport properties of these devices can be customized by fabricating them from PEG-DA gels of four distinct molecular weights. In contrast to microfluidic devices developed using soft lithography; this class of devices can be realized using a more cost-effective approach of direct photopolymerization with fewer microfabrication steps. This microfluidic platform was tested by conducting a quantitative study of the chemotactic behavior of Escherichia coli (E. coli) RP437, a model microorganism, in presence of the chemo-effector, casamino-acids. Using the microfabrication and characterization methodology presented in this work, microfluidic platforms with well-defined and customizable diffusive properties can be developed to accommodate the study of a wide range of cell types. (paper)

Molecular Imaging Probe Development using Microfluidics

Science.gov (United States)

Liu, Kan; Wang, Ming-Wei; Lin, Wei-Yu; Phung, Duy Linh; Girgis, Mark D.; Wu, Anna M.; Tomlinson, James S.; Shen, Clifton K.-F.

2012-01-01

In this manuscript, we review the latest advancement of microfluidics in molecular imaging probe development. Due to increasing needs for medical imaging, high demand for many types of molecular imaging probes will have to be met by exploiting novel chemistry/radiochemistry and engineering technologies to improve the production and development of suitable probes. The microfluidic-based probe synthesis is currently attracting a great deal of interest because of their potential to deliver many advantages over conventional systems. Numerous chemical reactions have been successfully performed in micro-reactors and the results convincingly demonstrate with great benefits to aid synthetic procedures, such as purer products, higher yields, shorter reaction times compared to the corresponding batch/macroscale reactions, and more benign reaction conditions. Several ‘proof-of-principle’ examples of molecular imaging probe syntheses using microfluidics, along with basics of device architecture and operation, and their potential limitations are discussed here. PMID:22977436

Cell Culture Microfluidic Biochips: Experimental Throughput Maximization

DEFF Research Database (Denmark)

Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan

2011-01-01

Microfluidic biochips offer a promising alternative to a conventional biochemical laboratory, integrating all necessary functionalities on-chip in order to perform biochemical applications. Researchers have started to propose computer-aided design tools for the synthesis of such biochips. Our focus...... metaheuristic for experimental design generation for the cell culture microfluidic biochips, and we have evaluated our approach using multiple experimental setups....

Modular microfluidic system for biological sample preparation

Science.gov (United States)

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.

Route to one-step microstructure mold fabrication for PDMS microfluidic chip

Science.gov (United States)

Lv, Xiaoqing; Geng, Zhaoxin; Fan, Zhiyuan; Wang, Shicai; Su, Yue; Fang, Weihao; Pei, Weihua; Chen, Hongda

2018-04-01

The microstructure mold fabrication for PDMS microfluidic chip remains complex and time-consuming process requiring special equipment and protocols: photolithography and etching. Thus, a rapid and cost-effective method is highly needed. Comparing with the traditional microfluidic chip fabricating process based on the micro-electromechanical system (MEMS), this method is simple and easy to implement, and the whole fabrication process only requires 1-2 h. Different size of microstructure from 100 to 1000 μm was fabricated, and used to culture four kinds of breast cancer cell lines. Cell viability and morphology was assessed when they were cultured in the micro straight channels, micro square holes and the bonding PDMS-glass microfluidic chip. The experimental results indicate that the microfluidic chip is good and meet the experimental requirements. This method can greatly reduce the process time and cost of the microfluidic chip, and provide a simple and effective way for the structure design and in the field of biological microfabrications and microfluidic chips.

Spontaneous oscillations in microfluidic networks

Science.gov (United States)

Case, Daniel; Angilella, Jean-Regis; Motter, Adilson

2017-11-01

Precisely controlling flows within microfluidic systems is often difficult which typically results in systems being heavily reliant on numerous external pumps and computers. Here, I present a simple microfluidic network that exhibits flow rate switching, bistablity, and spontaneous oscillations controlled by a single pressure. That is, by solely changing the driving pressure, it is possible to switch between an oscillating and steady flow state. Such functionality does not rely on external hardware and may even serve as an on-chip memory or timing mechanism. I use an analytic model and rigorous fluid dynamics simulations to show these results.

Collective oscillations and coupled modes in confined microfluidic droplet arrays

Science.gov (United States)

Schiller, Ulf D.; Fleury, Jean-Baptiste; Seemann, Ralf; Gompper, Gerhard

Microfluidic droplets have a wide range of applications ranging from analytic assays in cellular biology to controlled mixing in chemical engineering. Ensembles of microfluidic droplets are interesting model systems for non-equilibrium many-body phenomena. When flowing in a microchannel, trains of droplets can form microfluidic crystals whose dynamics are governed by long-range hydrodynamic interactions and boundary effects. In this contribution, excitation mechanisms for collective waves in dense and confined microfluidic droplet arrays are investigated by experiments and computer simulations. We demonstrate that distinct modes can be excited by creating specific `defect' patterns in flowing droplet trains. While longitudinal modes exhibit a short-lived cascade of pairs of laterally displacing droplets, transversely excited modes form propagating waves that behave like microfluidic phonons. We show that the confinement induces a coupling between longitudinal and transverse modes. We also investigate the life time of the collective oscillations and discuss possible mechanisms for the onset of instabilities. Our results demonstrate that microfluidic phonons can exhibit effects beyond the linear theory, which can be studied particularly well in dense and confined systems. This work was supported by Deutsche Forschungsgemeinschaft under Grant No. SE 1118/4.

CMOS Enabled Microfluidic Systems for Healthcare Based Applications.

Science.gov (United States)

Khan, Sherjeel M; Gumus, Abdurrahman; Nassar, Joanna M; Hussain, Muhammad M

2018-04-01

With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people-process-data-device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compilation and Synthesis for Fault-Tolerant Digital Microfluidic Biochips

DEFF Research Database (Denmark)

Alistar, Mirela

Microfluidic-based biochips are replacing the conventional biochemical analyzers, by integrating all the necessary functions for biochemical analysis using microfluidics. The digital microfluidic biochips (DMBs) manipulate discrete amounts of fluids of nanoliter volume, named droplets, on an array...... of the operations in the application. During the execution of a bioassay, operations could experience transient faults, thus impacting negatively the correctness of the application. We have proposed both offline (design time) and online (runtime) recovery strategies. The online recovery strategy decides...

Plastic-Based Structurally Programmable Microfluidic Biochips for Clinical Diagnostics

National Research Council Canada - National Science Library

Ahn, Chong H; Nevin, Joseph H; Beaucage, Gregory

2005-01-01

... and reliable measurements of metabolic parameters from a human body with minimum invasion. The fully integrated disposable biochip is capable of precise volume control with smart microfluidic manipulation without costly on-chip microfluidic components...

Printed wax masks for 254 nm deep-UV pattering of PMMA-based microfluidics

KAUST Repository

Fan, Yiqiang

2012-01-13

This paper reports a new technique for masking deep-UV exposure of poly(methyl methacrylate) (PMMA) using a printed wax mask. This technique provides an inexpensive and bulk fabrication method for PMMA structures. The technique involves the direct printing of the mask onto a polymer sheet using a commercial wax printer. The wax layer was then transferred to a PMMA substrate using a thermal laminator, exposed using deep-UV (with a wavelength of 254 nm), developed in an IPA:water solution, and completed by bonding on a PMMA cap layer. A sample microfluidic device fabricated with this method is also presented, with the microchannel as narrow as 50 μm. The whole process is easy to perform without the requirement for any microfabrication facilities. © 2012 IOP Publishing Ltd.

Microfluidic chemical reaction circuits

Science.gov (United States)

Lee, Chung-cheng [Irvine, CA; Sui, Guodong [Los Angeles, CA; Elizarov, Arkadij [Valley Village, CA; Kolb, Hartmuth C [Playa del Rey, CA; Huang, Jiang [San Jose, CA; Heath, James R [South Pasadena, CA; Phelps, Michael E [Los Angeles, CA; Quake, Stephen R [Stanford, CA; Tseng, Hsian-rong [Los Angeles, CA; Wyatt, Paul [Tipperary, IE; Daridon, Antoine [Mont-Sur-Rolle, CH

2012-06-26

New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

Optical two-beam traps in microfluidic systems

DEFF Research Database (Denmark)

Berg-Sørensen, Kirstine

2016-01-01

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...... written waveguides and in an injection molded polymer chip with grooves for optical fibers. (C) 2016 The Japan Society of Applied Physics....

In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method

International Nuclear Information System (INIS)

Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

2015-01-01

In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO 3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO 3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO 3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of carbonated

In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiaoguang [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Zhao, Xu [College of Chemistry, Jilin University, Changchun 130021 (China); Li, Yi, E-mail: lyi99@jlu.edu.cn [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Yang, Tao [Department of Stomatology, Children' s Hospital of Changchun, 130051 (China); Yan, Xiujuan; Wang, Ke [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China)

2015-09-01

In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO{sub 3} layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO{sub 3} layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO{sub 3} coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of

Particle-Based Microfluidic Device for Providing High Magnetic Field Gradients

Science.gov (United States)

Lin, Adam Y. (Inventor); Wong, Tak S. (Inventor)

2013-01-01

A microfluidic device for manipulating particles in a fluid has a device body that defines a main channel therein, in which the main channel has an inlet and an outlet. The device body further defines a particulate diverting channel therein, the particulate diverting channel being in fluid connection with the main channel between the inlet and the outlet of the main channel and having a particulate outlet. The microfluidic device also has a plurality of microparticles arranged proximate or in the main channel between the inlet of the main channel and the fluid connection of the particulate diverting channel to the main channel. The plurality of microparticles each comprises a material in a composition thereof having a magnetic susceptibility suitable to cause concentration of magnetic field lines of an applied magnetic field while in operation. A microfluidic particle-manipulation system has a microfluidic particle-manipulation device and a magnet disposed proximate the microfluidic particle-manipulation device.

Integration of Multiplexed Microfluidic Electrokinetic Concentrators with a Morpholino Microarray via Reversible Surface Bonding for Enhanced DNA Hybridization.

Science.gov (United States)

Martins, Diogo; Wei, Xi; Levicky, Rastislav; Song, Yong-Ak

2016-04-05

We describe a microfluidic concentration device to accelerate the surface hybridization reaction between DNA and morpholinos (MOs) for enhanced detection. The microfluidic concentrator comprises a single polydimethylsiloxane (PDMS) microchannel onto which an ion-selective layer of conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) was directly printed and then reversibly surface bonded onto a morpholino microarray for hybridization. Using this electrokinetic trapping concentrator, we could achieve a maximum concentration factor of ∼800 for DNA and a limit of detection of 10 nM within 15 min. In terms of the detection speed, it enabled faster hybridization by around 10-fold when compared to conventional diffusion-based hybridization. A significant advantage of our approach is that the fabrication of the microfluidic concentrator is completely decoupled from the microarray; by eliminating the need to deposit an ion-selective layer on the microarray surface prior to device integration, interfacing between both modules, the PDMS chip for electrokinetic concentration and the substrate for DNA sensing are easier and applicable to any microarray platform. Furthermore, this fabrication strategy facilitates a multiplexing of concentrators. We have demonstrated the proof-of-concept for multiplexing by building a device with 5 parallel concentrators connected to a single inlet/outlet and applying it to parallel concentration and hybridization. Such device yielded similar concentration and hybridization efficiency compared to that of a single-channel device without adding any complexity to the fabrication and setup. These results demonstrate that our concentrator concept can be applied to the development of a highly multiplexed concentrator-enhanced microarray detection system for either genetic analysis or other diagnostic assays.

Leveraging liquid dielectrophoresis for microfluidic applications

International Nuclear Information System (INIS)

Chugh, Dipankar; Kaler, Karan V I S

2008-01-01

Miniaturized fluidic systems have been developed in recent years and offer new and novel means of leveraging the domain of microfluidics for the development of micro-total analysis systems (μTAS). Initially, such systems employed closed microchannels in order to facilitate chip-based biochemical assays, requiring very small quantities of sample and/or reagents and furthermore providing rapid and low-cost analysis on a compact footprint. More recently, advancements in the domain of surface microfluidics have suggested that similar low volume sample handling and manipulation capabilities for bioassays can be attained by leveraging the phenomena of liquid dielectrophoresis and droplet dielectrophoresis (DEP), without the need for separate pumps or valves. Some of the key aspects of this surface microfluidic technology and its capabilities are discussed and highlighted in this paper. We, furthermore, examine the integration and utility of liquid DEP and droplet DEP in providing rapid and automated sample handling and manipulation capabilities on a compact chip-based platform

Designing Polymeric Microfluidic Platforms for Biomedical Applications

DEFF Research Database (Denmark)

Vedarethinam, Indumathi

Micro- and Nanotechnology have the potential to offer a smart solution for diagnostics and academia research with rapid, low cost, robust analysis systems to facilitate biological analyses. New, high throughput microfluidic platforms have the potential to surpass in performance the conventional...... analyses systems in use today. The overall goal of this PhD project is to address two different areas using microfluidics : i) Chromosome analysis by metaphase FISH such a platform, if successful, can immediately substitute the routine, labor-intensive, glass slide-based FISH analyses in Clinical...... Cytogenetics laboratories. During the course of this project, initially the suitability of the polymeric chip substrate was tested and a microfluidic device was developed for performing interphase FISH analysis. With this device, the key factors involved in chromosome spreading crucial to FISH analysis were...

Towards rapid prototyped convective microfluidic DNA amplification platform

Science.gov (United States)

Ajit, Smrithi; Praveen, Hemanth Mithun; Puneeth, S. B.; Dave, Abhishek; Sesham, Bharat; Mohan, K. N.; Goel, Sanket

2017-02-01

Today, Polymerase Chain Reaction (PCR) based DNA amplification plays an indispensable role in the field of biomedical research. Its inherent ability to exponentially amplify sample DNA has proven useful for the identification of virulent pathogens like those causing Multiple Drug-Resistant Tuberculosis (MDR-TB). The intervention of Microfluidics technology has revolutionized the concept of PCR from being a laborious and time consuming process into one that is faster, easily portable and capable of being multifunctional. The Microfluidics based PCR outweighs its traditional counterpart in terms of flexibility of varying reaction rate, operation simplicity, need of a fraction of volume and capability of being integrated with other functional elements. The scope of the present work involves the development of a real-time continuous flow microfluidic device, fabricated by 3D printing-governed rapid prototyping method, eventually leading to an automated and robust platform to process multiple DNA samples for detection of MDRTB-associated mutations. The thermal gradient characteristic to the PCR process is produced using peltier units appropriate to the microfluidic environment fully monitored and controlled by a low cost controller driven by a Data Acquisition System. The process efficiency achieved in the microfluidic environment in terms of output per cycle is expected to be on par with the traditional PCR and capable of earning the additional advantages of being faster and minimizing the handling.

Microfluidic method for measuring viscosity using images from smartphone

Science.gov (United States)

Kim, Sooyeong; Kim, Kyung Chun; Yeom, Eunseop

2018-05-01

The viscosity of a fluid is the most important characteristic in fluid rheology. Many microfluidic devices have been proposed for easily measuring the fluid viscosity of small samples. A hybrid system consisting of a smartphone and microfluidic device can offer a mobile laboratory for performing a wide range of detection and analysis functions related to healthcare. In this study, a new mobile sensing method based on a microfluidic device was proposed for fluid viscosity measurements. By separately delivering sample and reference fluids into the two inlets of a Y-shaped microfluidic device, an interfacial line is induced at downstream of the device. Because the interfacial width (W) between the sample and reference fluid flows was determined by their pressure ratio, the viscosity (μ) of the sample could be estimated by measuring the interfacial width. To distinguish the interfacial width of a sample, optical images of the flows at downstream of the Y-shaped microfluidic device were acquired using a smartphone. To check the measurement accuracy of the proposed method, the viscosities of glycerol mixtures were compared with those measured by a conventional viscometer. The proposed technique was applied to monitor the variations in blood and oil samples depending on storage or rancidity. We expect that this mobile sensing method based on a microfluidic device could be utilized as a viscometer with significant advantages in terms of mobility, ease-of-operation, and data management.

Engineering and evaluating drug delivery particles in microfluidic devices.

Science.gov (United States)

Björnmalm, Mattias; Yan, Yan; Caruso, Frank

2014-09-28

The development of new and improved particle-based drug delivery is underpinned by an enhanced ability to engineer particles with high fidelity and integrity, as well as increased knowledge of their biological performance. Microfluidics can facilitate these processes through the engineering of spatiotemporally highly controlled environments using designed microstructures in combination with physical phenomena present at the microscale. In this review, we discuss microfluidics in the context of addressing key challenges in particle-based drug delivery. We provide an overview of how microfluidic devices can: (i) be employed to engineer particles, by providing highly controlled interfaces, and (ii) be used to establish dynamic in vitro models that mimic in vivo environments for studying the biological behavior of engineered particles. Finally, we discuss how the flexible and modular nature of microfluidic devices provides opportunities to create increasingly realistic models of the in vivo milieu (including multi-cell, multi-tissue and even multi-organ devices), and how ongoing developments toward commercialization of microfluidic tools are opening up new opportunities for the engineering and evaluation of drug delivery particles. Copyright © 2014 Elsevier B.V. All rights reserved.

Parameter Screening in Microfluidics Based Hydrodynamic Single-Cell Trapping

Directory of Open Access Journals (Sweden)

B. Deng

2014-01-01

Full Text Available Microfluidic cell-based arraying technology is widely used in the field of single-cell analysis. However, among developed devices, there is a compromise between cellular loading efficiencies and trapped cell densities, which deserves further analysis and optimization. To address this issue, the cell trapping efficiency of a microfluidic device with two parallel micro channels interconnected with cellular trapping sites was studied in this paper. By regulating channel inlet and outlet status, the microfluidic trapping structure can mimic key functioning units of previously reported devices. Numerical simulations were used to model this cellular trapping structure, quantifying the effects of channel on/off status and trapping structure geometries on the cellular trapping efficiency. Furthermore, the microfluidic device was fabricated based on conventional microfabrication and the cellular trapping efficiency was quantified in experiments. Experimental results showed that, besides geometry parameters, cellular travelling velocities and sizes also affected the single-cell trapping efficiency. By fine tuning parameters, more than 95% of trapping sites were taken by individual cells. This study may lay foundation in further studies of single-cell positioning in microfluidics and push forward the study of single-cell analysis.

Simple and Versatile 3D Printed Microfluidics Using Fused Filament Fabrication.

Directory of Open Access Journals (Sweden)

Alex J L Morgan

Full Text Available The uptake of microfluidics by the wider scientific community has been limited by the fabrication barrier created by the skills and equipment required for the production of traditional microfluidic devices. Here we present simple 3D printed microfluidic devices using an inexpensive and readily accessible printer with commercially available printer materials. We demonstrate that previously reported limitations of transparency and fidelity have been overcome, whilst devices capable of operating at pressures in excess of 2000 kPa illustrate that leakage issues have also been resolved. The utility of the 3D printed microfluidic devices is illustrated by encapsulating dental pulp stem cells within alginate droplets; cell viability assays show the vast majority of cells remain live, and device transparency is sufficient for single cell imaging. The accessibility of these devices is further enhanced through fabrication of integrated ports and by the introduction of a Lego®-like modular system facilitating rapid prototyping whilst offering the potential for novices to build microfluidic systems from a database of microfluidic components.

Simple and Versatile 3D Printed Microfluidics Using Fused Filament Fabrication.

Science.gov (United States)

Morgan, Alex J L; Hidalgo San Jose, Lorena; Jamieson, William D; Wymant, Jennifer M; Song, Bing; Stephens, Phil; Barrow, David A; Castell, Oliver K

2016-01-01

The uptake of microfluidics by the wider scientific community has been limited by the fabrication barrier created by the skills and equipment required for the production of traditional microfluidic devices. Here we present simple 3D printed microfluidic devices using an inexpensive and readily accessible printer with commercially available printer materials. We demonstrate that previously reported limitations of transparency and fidelity have been overcome, whilst devices capable of operating at pressures in excess of 2000 kPa illustrate that leakage issues have also been resolved. The utility of the 3D printed microfluidic devices is illustrated by encapsulating dental pulp stem cells within alginate droplets; cell viability assays show the vast majority of cells remain live, and device transparency is sufficient for single cell imaging. The accessibility of these devices is further enhanced through fabrication of integrated ports and by the introduction of a Lego®-like modular system facilitating rapid prototyping whilst offering the potential for novices to build microfluidic systems from a database of microfluidic components.

Integration of micro nano and bio technologies with layer-by-layer self-assembly

Science.gov (United States)

Kommireddy, Dinesh Shankar

In the past decade, layer-by-layer (LbL) nanoassembly has been used as a tool for immobilization and surface modification of materials with applications in biology and physical sciences. Often, in such applications, LbL assembly is integrated with various techniques to form functional surface coatings and immobilized matrices. In this work, integration of LbL with microfabrication and microfluidics, and tissue engineering are explored. In an effort to integrate microfabrication with LbL nanoassembly, microchannels were fabricated using soft-lithography and the surface of these channels was used for the immobilization of materials using LbL and laminar flow patterning. Synthesis of poly(dimethyldiallyl ammonium chloride)/poly(styrene sulfonate) and poly(dimethyldiallyl ammonium chloride)/bovine serum albumin microstrips is demonstrated with the laminar flow microfluidic reactor. Resulting micropatterns are 8-10 mum wide, separated with few micron gaps. The width of these microstrips as well as their position in the microchannel is controlled by varying the flow rate, time of interaction and concentration of the individual components, which is verified by numerical simulation. Spatially resolved pH sensitivity was observed by modifying the surface of the channel with a pH sensitive dye. In order to investigate the integration of LbL assembly with tissue engineering, glass substrates were coated with nanoparticle/polyelectrolyte layers, and two different cell types were used to test the applicability of these coatings for the surface modification of medical implants. Titanium dioxide (TiO 2), silicon dioxide, halloysite and montmorillonite nanoparticles were assembled with oppositely charged polyelectrolytes. In-vitro cytotoxicity tests of the nanoparticle substrates on human dermal firbroblasts (HDFs) showed that the nanoparticle surfaces do not have toxic effects on the cells. HDFs retained their phenotype on the nanoparticle coatings, by synthesizing type

3D Ceramic Microfluidic Device Manufacturing

International Nuclear Information System (INIS)

Natarajan, Govindarajan; Humenik, James N

2006-01-01

Today, semiconductor processing serves as the backbone for the bulk of micromachined devices. Precision lithography and etching technology used in the semiconductor industry are also leveraged by alternate techniques like electroforming and molding. The nature of such processing is complex, limited and expensive for any manufacturing foundry. This paper details the technology elements developed to manufacture cost effective and versatile microfluidic devices for applications ranging from medical diagnostics to characterization of bioassays. Two applications using multilayer ceramic technology to manufacture complex 3D microfluidic devices are discussed

Microfluidic device for drug delivery

Science.gov (United States)

Beebe, David J. (Inventor); MacDonald, Michael J. (Inventor); Eddington, David T. (Inventor); Mensing, Glennys A. (Inventor)

2010-01-01

A microfluidic device is provided for delivering a drug to an individual. The microfluidic device includes a body that defines a reservoir for receiving the drug therein. A valve interconnects the reservoir to an output needle that is insertable into the skin of an individual. A pressure source urges the drug from the reservoir toward the needle. The valve is movable between a closed position preventing the flow of the drug from the reservoir to the output needle and an open position allowing for the flow of the drug from the reservoir to the output needle in response to a predetermined condition in the physiological fluids of the individual.

Microfluidic Device

Science.gov (United States)

Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Lin, Jeffrey Chun-Hui (Inventor); Kasdan, Harvey L. (Inventor)

2017-01-01

Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

Microfluidic biosensing device for controlled trapping and detection of magnetic microparticles

KAUST Repository

Giouroudi, Ioanna

2013-05-01

A magnetic microfluidic device is proposed to transport and trap magnetic microparticles (MPs) to a sensing area. Once the MPs are concentrated in the vicinity of the sensing area, a spin valve type giant magnetoresistance (GMR) sensor is used to detect their presence. The device is used for the detection of biological targets once they are labeled with functionalized MPs. Manipulation of the MPs is achieved by employing a microstructure which consists of planar ringshaped conducting microloops. These microloops are designed to produce high magnetic field gradients which are directly proportional to the force applied to manipulate the MPs. Upon sequential application of current, starting from the outermost loop, MPs are directed to move from the outermost to the innermost loop. The speed with which the MPs move towards the sensing area is controlled by the speed with which current is switched between the loops. On top of the microstructure, a microfluidic channel is fabricated using a standard photolithography technique and a dry film resist layer (Ordyl SY355). Experimental results showed that MPs of different diameters were successfully trapped at the sensing area and detected by the GMR sensor located directly under the innermost square loop. © 2013 IEEE.

Rapid fabrication of microfluidic polymer electrolyte membrane fuel cell in PDMS by surface patterning of perfluorinated ion-exchange resin

Energy Technology Data Exchange (ETDEWEB)

Song, Yong-Ak; Han, Jongyoon [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Batista, Candy [Roxbury Community College, 1234 Columbus Ave., Roxbury Crossing, MA 02120 (United States); Sarpeshkar, Rahul [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

2008-09-01

In this paper we demonstrate a simple and rapid fabrication method for a microfluidic polymer electrolyte membrane (PEM) fuel cell using polydimethylsiloxane (PDMS), which has become the de facto standard material in BioMEMS. Instead of integrating a Nafion sheet film between two layers of a PDMS device in a traditional ''sandwich format,'' we pattern a perfluorinated ion-exchange resin such as a Nafion resin on a glass substrate using a reversibly bonded PDMS microchannel to generate an ion-selective membrane between the fuel-cell electrodes. After this patterning step, the assembly of the microfluidic fuel cell is accomplished by simple oxygen plasma bonding between the PDMS chip and the glass substrate. In an example implementation, the planar PEM microfluidic fuel cell generates an open circuit voltage of 600-800 mV and delivers a maximum current output of nearly 4 {mu}A. To enhance the power output of the fuel cell we utilize self-assembled colloidal arrays as a support matrix for the Nafion resin. Such arrays allow us to increase the thickness of the ion-selective membrane to 20 {mu}m and increase the current output by 166%. Our novel fabrication method enables rapid prototyping of microfluidic fuel cells to study various ion-exchange resins for the polymer electrolyte membrane. Our work will facilitate the development of miniature, implantable, on-chip power sources for biomedical applications. (author)

Recent Advances in Magnetic Microfluidic Biosensors

Directory of Open Access Journals (Sweden)

Ioanna Giouroudi

2017-07-01

Full Text Available The development of portable biosening devices for the detection of biological entities such as biomolecules, pathogens, and cells has become extremely significant over the past years. Scientific research, driven by the promise for miniaturization and integration of complex laboratory equipment on inexpensive, reliable, and accurate devices, has successfully shifted several analytical and diagnostic methods to the submillimeter scale. The miniaturization process was made possible with the birth of microfluidics, a technology that could confine, manipulate, and mix very small volumes of liquids on devices integrated on standard silicon technology chips. Such devices are then directly translating the presence of these entities into an electronic signal that can be read out with a portable instrumentation. For the aforementioned tasks, the use of magnetic markers (magnetic particles—MPs—functionalized with ligands in combination with the application of magnetic fields is being strongly investigated by research groups worldwide. The greatest merits of using magnetic fields are that they can be applied either externally or from integrated microconductors and they can be well-tuned by adjusting the applied current on the microconductors. Moreover, the magnetic markers can be manipulated inside microfluidic channels by high gradient magnetic fields that can in turn be detected by magnetic sensors. All the above make this technology an ideal candidate for the development of such microfluidic biosensors. In this review, focus is given only to very recent advances in biosensors that use microfluidics in combination with magnetic sensors and magnetic markers/nanoparticles.

Integrated microchip incorporating atomic magnetometer and microfluidic channel for NMR and MRI

Science.gov (United States)

Ledbetter, Micah P [Oakland, CA; Savukov, Igor M [Los Alamos, NM; Budker, Dmitry [El Cerrito, CA; Shah, Vishal K [Plainsboro, NJ; Knappe, Svenja [Boulder, CO; Kitching, John [Boulder, CO; Michalak, David J [Berkeley, CA; Xu, Shoujun [Houston, TX; Pines, Alexander [Berkeley, CA

2011-08-09

An integral microfluidic device includes an alkali vapor cell and microfluidic channel, which can be used to detect magnetism for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). Small magnetic fields in the vicinity of the vapor cell can be measured by optically polarizing and probing the spin precession in the small magnetic field. This can then be used to detect the magnetic field of in encoded analyte in the adjacent microfluidic channel. The magnetism in the microfluidic channel can be modulated by applying an appropriate series of radio or audio frequency pulses upstream from the microfluidic chip (the remote detection modality) to yield a sensitive means of detecting NMR and MRI.

Formation of three-dimensional ZnSe-based semiconductor nanostructures

International Nuclear Information System (INIS)

Alyshev, S. V.; Zabezhaylov, A. O.; Mironov, R. A.; Kozlovsky, V. I.; Dianov, E. M.

2010-01-01

Nanostructures consisting of a 10-nm-thick sacrificial layer of ZnMgSSe and a 20-nm-thick stressed bilayer of ZnSSe/ZnSe were grown by molecular-beam epitaxy on GaAs substrates. Upon removal of the sacrificial layer by selective etching, multiwall ZnSSe/ZnSe microtubes were formed.

Surface-Enhanced Raman Spectroscopy Integrated Centrifugal Microfluidics Platform

DEFF Research Database (Denmark)

Durucan, Onur

This PhD thesis demonstrates (i) centrifugal microfluidics disc platform integrated with Au capped nanopillar (NP) substrates for surface-enhanced Raman spectroscopy (SERS) based sensing, and (ii) novel sample analysis concepts achieved by synergistical combination of sensing techniques and minia......This PhD thesis demonstrates (i) centrifugal microfluidics disc platform integrated with Au capped nanopillar (NP) substrates for surface-enhanced Raman spectroscopy (SERS) based sensing, and (ii) novel sample analysis concepts achieved by synergistical combination of sensing techniques...... dense array of NP structures. Furthermore, the wicking assisted nanofiltration procedure was accomplished in centrifugal microfluidics platform and as a result additional sample purification was achieved through the centrifugation process. In this way, the Au coated NP substrate was utilized...

Enhancing Single Molecule Imaging in Optofluidics and Microfluidics

Directory of Open Access Journals (Sweden)

Andreas E. Vasdekis

2011-08-01

Full Text Available Microfluidics and optofluidics have revolutionized high-throughput analysis and chemical synthesis over the past decade. Single molecule imaging has witnessed similar growth, due to its capacity to reveal heterogeneities at high spatial and temporal resolutions. However, both resolution types are dependent on the signal to noise ratio (SNR of the image. In this paper, we review how the SNR can be enhanced in optofluidics and microfluidics. Starting with optofluidics, we outline integrated photonic structures that increase the signal emitted by single chromophores and minimize the excitation volume. Turning then to microfluidics, we review the compatible functionalization strategies that reduce noise stemming from non-specific interactions and architectures that minimize bleaching and blinking.

Equilibrium and Nonequilibrium States in Microfluidic Double Emulsions

DEFF Research Database (Denmark)

Pannacci, N.; Bruus, Henrik; Bartolo, D.

2008-01-01

We describe experimental and theoretical studies dedicated to establishing the physics of formation of double droplets in microfluidic systems. We show that the morphologies (complete engulfing, partial engulfing, and nonengulfing) obtained at late times minimize the interfacial energy of the sys......We describe experimental and theoretical studies dedicated to establishing the physics of formation of double droplets in microfluidic systems. We show that the morphologies (complete engulfing, partial engulfing, and nonengulfing) obtained at late times minimize the interfacial energy...... of the system. We explain that nonequilibrium morphologies generated in the system can have long lifetimes. Remarkably, the physics of formation of the double droplets with microfluidics allows the synthesis of particles with new morphologies....

Electrogates for stop-and-go control of liquid flow in microfluidics

Science.gov (United States)

Arango, Y.; Temiz, Y.; Gökçe, O.; Delamarche, E.

2018-04-01

Diagnostics based on microfluidic devices necessitate specific reagents, flow conditions, and kinetics for optimal performance. Such an optimization is often achieved using assay-specific microfluidic chip designs or systems with external liquid pumps. Here, we present "electrogates" for stop-and-go control of flow of liquids in capillary-driven microfluidic chips by combining liquid pinning and electrowetting. Electrogates are simple to fabricate and efficient: a sample pipetted to a microfluidic chip flows autonomously in 15-μm-deep hydrophilic channels until the liquid meniscus is pinned at the edge of a 1.5-μm-deep trench patterned at the bottom of a rectangular microchannel. The flow can then be resumed by applying a DC voltage between the liquid and the trench via integrated electrodes. Using a trench geometry with a semicircular shape, we show that retention times longer than 30 min are achieved for various aqueous solutions such as biological buffers, artificial urine, and human serum. We studied the activation voltage and activation delay of electrogates using a chip architecture having 6 independent flow paths and experimentally showed that the flow can be resumed in less than 1 s for voltages smaller than 10 V, making this technique compatible with low-power and portable microfluidic systems. Electrogates therefore can make capillary-driven microfluidic chips very versatile by adding flow control in microfluidic channels in a flexible manner.

Microfluidics for Antibiotic Susceptibility and Toxicity Testing

Directory of Open Access Journals (Sweden)

Jing Dai

2016-10-01

Full Text Available The recent emergence of antimicrobial resistance has become a major concern for worldwide policy makers as very few new antibiotics have been developed in the last twenty-five years. To prevent the death of millions of people worldwide, there is an urgent need for a cheap, fast and accurate set of tools and techniques that can help to discover and develop new antimicrobial drugs. In the past decade, microfluidic platforms have emerged as potential systems for conducting pharmacological studies. Recent studies have demonstrated that microfluidic platforms can perform rapid antibiotic susceptibility tests to evaluate antimicrobial drugs’ efficacy. In addition, the development of cell-on-a-chip and organ-on-a-chip platforms have enabled the early drug testing, providing more accurate insights into conventional cell cultures on the drug pharmacokinetics and toxicity, at the early and cheaper stage of drug development, i.e., prior to animal and human testing. In this review, we focus on the recent developments of microfluidic platforms for rapid antibiotics susceptibility testing, investigating bacterial persistence and non-growing but metabolically active (NGMA bacteria, evaluating antibiotic effectiveness on biofilms and combinatorial effect of antibiotics, as well as microfluidic platforms that can be used for in vitro antibiotic toxicity testing.

Design and Testing of Digital Microfluidic Biochips

CERN Document Server

Zhao, Yang

2013-01-01

This book provides a comprehensive methodology for automated design, test and diagnosis, and use of robust, low-cost, and manufacturable digital microfluidic systems. It focuses on the development of a comprehensive CAD optimization framework for digital microfluidic biochips that unifies different design problems. With the increase in system complexity and integration levels, biochip designers can utilize the design methods described in this book to evaluate different design alternatives, and carry out design-space exploration to obtain the best design point. Describes practical design automation tools that address different design problems (e.g., synthesis, droplet routing, control-pin mapping, testing and diagnosis, and error recovery) in a unified manner; Applies test pattern generation and error-recovery techniques for digital microfluidics-based biochips; Uses real bioassays as evaluation examples, e.g., multiplexed in vitro human physiological fluids diagnostics, PCR, protein crystallization.  

Fabrication and Operation of Microfluidic Hanging-Drop Networks.

Science.gov (United States)

Misun, Patrick M; Birchler, Axel K; Lang, Moritz; Hierlemann, Andreas; Frey, Olivier

2018-01-01

The hanging-drop network (HDN) is a technology platform based on a completely open microfluidic network at the bottom of an inverted, surface-patterned substrate. The platform is predominantly used for the formation, culturing, and interaction of self-assembled spherical microtissues (spheroids) under precisely controlled flow conditions. Here, we describe design, fabrication, and operation of microfluidic hanging-drop networks.

Microfluidic devices and methods for integrated flow cytometry

Science.gov (United States)

Srivastava, Nimisha [Goleta, CA; Singh, Anup K [Danville, CA

2011-08-16

Microfluidic devices and methods for flow cytometry are described. In described examples, various sample handling and preparation steps may be carried out within a same microfluidic device as flow cytometry steps. A combination of imaging and flow cytometry is described. In some examples, spiral microchannels serve as incubation chambers. Examples of automated sample handling and flow cytometry are described.

Reversible thermo-pneumatic valves on centrifugal microfluidic platforms.

Science.gov (United States)

Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Kazemzadeh, Amin; Rothan, Hussin A; Yusof, Rohana; Madou, Marc

2015-08-21

Centrifugal microfluidic systems utilize a conventional spindle motor to automate parallel biochemical assays on a single microfluidic disk. The integration of complex, sequential microfluidic procedures on these platforms relies on robust valving techniques that allow for the precise control and manipulation of fluid flow. The ability of valves to consistently return to their former conditions after each actuation plays a significant role in the real-time manipulation of fluidic operations. In this paper, we introduce an active valving technique that operates based on the deflection of a latex film with the potential for real-time flow manipulation in a wide range of operational spinning speeds. The reversible thermo-pneumatic valve (RTPV) seals or reopens an inlet when a trapped air volume is heated or cooled, respectively. The RTPV is a gas-impermeable valve composed of an air chamber enclosed by a latex membrane and a specially designed liquid transition chamber that enables the efficient usage of the applied thermal energy. Inputting thermo-pneumatic (TP) energy into the air chamber deflects the membrane into the liquid transition chamber against an inlet, sealing it and thus preventing fluid flow. From this point, a centrifugal pressure higher than the induced TP pressure in the air chamber reopens the fluid pathway. The behaviour of this newly introduced reversible valving system on a microfluidic disk is studied experimentally and theoretically over a range of rotational frequencies from 700 RPM to 2500 RPM. Furthermore, adding a physical component (e.g., a hemispherical rubber element) to induce initial flow resistance shifts the operational range of rotational frequencies of the RTPV to more than 6000 RPM. An analytical solution for the cooling of a heated RTPV on a spinning disk is also presented, which highlights the need for the future development of time-programmable RTPVs. Moreover, the reversibility and gas impermeability of the RTPV in the

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

Science.gov (United States)

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

2016-06-21

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

Microfluidic System Simulation Including the Electro-Viscous Effect

Science.gov (United States)

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.

Toward a solid-phase nucleic acid hybridization assay within microfluidic channels using immobilized quantum dots as donors in fluorescence resonance energy transfer.

Science.gov (United States)

Chen, Lu; Algar, W Russ; Tavares, Anthony J; Krull, Ulrich J

2011-01-01

The optical properties and surface area of quantum dots (QDs) have made them an attractive platform for the development of nucleic acid biosensors based on fluorescence resonance energy transfer (FRET). Solid-phase assays based on FRET using mixtures of immobilized QD-oligonucleotide conjugates (QD biosensors) have been developed. The typical challenges associated with solid-phase detection strategies include non-specific adsorption, slow kinetics of hybridization, and sample manipulation. The new work herein has considered the immobilization of QD biosensors onto the surfaces of microfluidic channels in order to address these challenges. Microfluidic flow can be used to dynamically control stringency by adjustment of the potential in an electrokinetic-based microfluidics environment. The shearing force, Joule heating, and the competition between electroosmotic and electrophoretic mobilities allow the optimization of hybridization conditions, convective delivery of target to the channel surface to speed hybridization, amelioration of adsorption, and regeneration of the sensing surface. Microfluidic flow can also be used to deliver (for immobilization) and remove QD biosensors. QDs that were conjugated with two different oligonucleotide sequences were used to demonstrate feasibility. One oligonucleotide sequence on the QD was available as a linker for immobilization via hybridization with complementary oligonucleotides located on a glass surface within a microfluidic channel. A second oligonucleotide sequence on the QD served as a probe to transduce hybridization with target nucleic acid in a sample solution. A Cy3 label on the target was excited by FRET using green-emitting CdSe/ZnS QD donors and provided an analytical signal to explore this detection strategy. The immobilized QDs could be removed under denaturing conditions by disrupting the duplex that was used as the surface linker and thus allowed a new layer of QD biosensors to be re-coated within the channel

3D Printed Paper-Based Microfluidic Analytical Devices

Directory of Open Access Journals (Sweden)

Yong He

2016-06-01

Full Text Available As a pump-free and lightweight analytical tool, paper-based microfluidic analytical devices (μPADs attract more and more interest. If the flow speed of μPAD can be programmed, the analytical sequences could be designed and they will be more popular. This reports presents a novel μPAD, driven by the capillary force of cellulose powder, printed by a desktop three-dimensional (3D printer, which has some promising features, such as easy fabrication and programmable flow speed. First, a suitable size-scale substrate with open microchannels on its surface is printed. Next, the surface of the substrate is covered with a thin layer of polydimethylsiloxane (PDMS to seal the micro gap caused by 3D printing. Then, the microchannels are filled with a mixture of cellulose powder and deionized water in an appropriate proportion. After drying in an oven at 60 °C for 30 min, it is ready for use. As the different channel depths can be easily printed, which can be used to achieve the programmable capillary flow speed of cellulose powder in the microchannels. A series of microfluidic analytical experiments, including quantitative analysis of nitrite ion and fabrication of T-sensor were used to demonstrate its capability. As the desktop 3D printer (D3DP is very cheap and accessible, this device can be rapidly printed at the test field with a low cost and has a promising potential in the point-of-care (POC system or as a lightweight platform for analytical chemistry.

Confined methane-water interfacial layers and thickness measurements using in situ Raman spectroscopy.

Science.gov (United States)

Pinho, Bruno; Liu, Yukun; Rizkin, Benjamin; Hartman, Ryan L

2017-11-07

Gas-liquid interfaces broadly impact our planet, yet confined interfaces behave differently than unconfined ones. We report the role of tangential fluid motion in confined methane-water interfaces. The interfaces are created using microfluidics and investigated by in situ 1D, 2D and 3D Raman spectroscopy. The apparent CH 4 and H 2 O concentrations are reported for Reynolds numbers (Re), ranging from 0.17 to 8.55. Remarkably, the interfaces are comprised of distinct layers of thicknesses varying from 23 to 57 μm. We found that rarefaction, mixture, thin film, and shockwave layers together form the interfaces. The results indicate that the mixture layer thickness (δ) increases with Re (δ ∝ Re), and traditional transport theory for unconfined interfaces does not explain the confined interfaces. A comparison of our results with thin film theory of air-water interfaces (from mass transfer experiments in capillary microfluidics) supports that the hydrophobicity of CH 4 could decrease the strength of water-water interactions, resulting in larger interfacial thicknesses. Our findings help explain molecular transport in confined gas-liquid interfaces, which are common in a broad range of societal applications.

Quantitative Collection and Enzymatic Activity of Glucose Oxidase Nanotubes Fabricated by Templated Layer-by-Layer Assembly.

Science.gov (United States)

Zhang, Shouwei; Demoustier-Champagne, Sophie; Jonas, Alain M

2015-08-10

We report on the fabrication of enzyme nanotubes in nanoporous polycarbonate membranes via the layer-by-layer (LbL) alternate assembly of polyethylenimine (PEI) and glucose oxidase (GOX), followed by dissolution of the sacrificial template in CH2Cl2, collection, and final dispersion in water. An adjuvant-assisted filtration methodology is exploited to extract quantitatively the nanotubes without loss of activity and morphology. Different water-soluble CH2Cl2-insoluble adjuvants are tested for maximal enzyme activity and nanotube stability; whereas NaCl disrupts the tubes by screening electrostatic interactions, the high osmotic pressure created by fructose also contributes to loosening the nanotubular structures. These issues are solved when using neutral, high molar mass dextran. The enzymatic activity of intact free nanotubes in water is then quantitatively compared to membrane-embedded nanotubes, showing that the liberated nanotubes have a higher catalytic activity in proportion to their larger exposed surface. Our study thus discloses a robust and general methodology for the fabrication and quantitative collection of enzymatic nanotubes and shows that LbL assembly provides access to efficient enzyme carriers for use as catalytic swarming agents.

The microfluidic probe: operation and use for localized surface processing.

Science.gov (United States)

Perrault, Cecile M; Qasaimeh, Mohammad A; Juncker, David

2009-06-04

Microfluidic devices allow assays to be performed using minute amounts of sample and have recently been used to control the microenvironment of cells. Microfluidics is commonly associated with closed microchannels which limit their use to samples that can be introduced, and cultured in the case of cells, within a confined volume. On the other hand, micropipetting system have been used to locally perfuse cells and surfaces, notably using push-pull setups where one pipette acts as source and the other one as sink, but the confinement of the flow is difficult in three dimensions. Furthermore, pipettes are fragile and difficult to position and hence are used in static configuration only. The microfluidic probe (MFP) circumvents the constraints imposed by the construction of closed microfluidic channels and instead of enclosing the sample into the microfluidic system, the microfluidic flow can be directly delivered onto the sample, and scanned across the sample, using the MFP. . The injection and aspiration openings are located within a few tens of micrometers of one another so that a microjet injected into the gap is confined by the hydrodynamic forces of the surrounding liquid and entirely aspirated back into the other opening. The microjet can be flushed across the substrate surface and provides a precise tool for localized deposition/delivery of reagents which can be used over large areas by scanning the probe across the surface. In this video we present the microfluidic probe (MFP). We explain in detail how to assemble the MFP, mount it atop an inverted microscope, and align it relative to the substrate surface, and finally show how to use it to process a substrate surface immersed in a buffer.

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

Science.gov (United States)

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

PRESSURE-IMPULSE DIAGRAM OF MULTI-LAYERED ALUMINUM FOAM PANELS UNDER BLAST PRESSURE

Directory of Open Access Journals (Sweden)

CHANG-SU SHIM

2013-06-01

Full Text Available Anti-terror engineering has increasing demand in construction industry, but basis of design (BOD is normally not clear for designers. Hardening of structures has limitations when design loads are not defined. Sacrificial foam claddings are one of the most efficient methods to protect blast pressure. Aluminum foam can have designed yield strength according to relative density and mitigate the blast pressure below a target transmitted pressure. In this paper, multi-layered aluminum foam panels were proposed to enhance the pressure mitigation by increasing effective range of blast pressure. Through explicit finite element analyses, the performance of blast pressure mitigation by the multi-layered foams was evaluated. Pressure-impulse diagrams for the foam panels were developed from extensive analyses. Combination of low and high strength foams showed better applicability in wider range of blast pressure.

A novel 3-D bio-microfluidic system mimicking in vivo heterogeneous tumour microstructures reveals complex tumour–stroma interactions

KAUST Repository

Fan, Qihui

2017-07-10

A 3-D microfluidic system consisting of microchamber arrays embedded in a collagen hydrogel with tuneable biochemical gradients that mimics the tumour microenvironment of mammary glands was constructed for the investigation on the interactions between invasive breast cancer cells and stromal cells. The hollow microchambers in collagen provide a very similar 3-D environment to that in vivo that regulates collective cellular dynamics and behaviour, while the microfluidic channels surrounding the collagen microchamber arrays allow one to impose complex concentration gradients of specific biological molecules or drugs. We found that breast epithelial cells (MCF-10A) seeded in the microchambers formed lumen-like structures similar to those in epithelial layers. When MCF-10A cells were co-cultured with invasive breast cancer cells (MDA-MB-231), the formation of lumen-like structures in the microchambers was inhibited, indicating the capability of cancer cells to disrupt the structures formed by surrounding cells for further invasion and metastasis. Subsequent mechanism studies showed that down regulation of E-cad expression due to MMPs produced by the cancer cells plays a dominant role in determining the cellular behaviour. Our microfluidic system offers a robust platform for high throughput studies that aim to understand combinatorial effects of multiple biochemical and microenvironmental factors.

Evaluation of microfluidic channels with optical coherence tomography

KAUST Repository

Czajkowski, J.; Prykä ri, T.; Alarousu, E.; Lauri, J.; Myllylä , R.

2010-01-01

Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in evaluation of microfluidic channels is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, a photonic crystal fibre and modified, free-space Michelson interferometer. To show potential of the technique, microfluidic chip fabricated by VTT Center for Printed Intelligence (Oulu, Finland) was measured. Ability for full volumetric reconstruction in non-contact manner enabled complete characterization of closed entity of a microfluidic channel without contamination and harm for the sample. Measurement, occurring problems, and methods of postprocessing for raw data are described. Results present completely resolved physical structure of the channel, its spatial dimensions, draft angles and evaluation of lamination quality.

Evaluation of microfluidic channels with optical coherence tomography

KAUST Repository

Czajkowski, J.

2010-06-25

Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in evaluation of microfluidic channels is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, a photonic crystal fibre and modified, free-space Michelson interferometer. To show potential of the technique, microfluidic chip fabricated by VTT Center for Printed Intelligence (Oulu, Finland) was measured. Ability for full volumetric reconstruction in non-contact manner enabled complete characterization of closed entity of a microfluidic channel without contamination and harm for the sample. Measurement, occurring problems, and methods of postprocessing for raw data are described. Results present completely resolved physical structure of the channel, its spatial dimensions, draft angles and evaluation of lamination quality.

Evaluation of microfluidic channels with optical coherence tomography

Science.gov (United States)

Czajkowski, J.; Prykäri, T.; Alarousu, E.; Lauri, J.; Myllylä, R.

2010-11-01

Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in evaluation of microfluidic channels is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, a photonic crystal fibre and modified, free-space Michelson interferometer. To show potential of the technique, microfluidic chip fabricated by VTT Center for Printed Intelligence (Oulu, Finland) was measured. Ability for full volumetric reconstruction in non-contact manner enabled complete characterization of closed entity of a microfluidic channel without contamination and harm for the sample. Measurement, occurring problems, and methods of postprocessing for raw data are described. Results present completely resolved physical structure of the channel, its spatial dimensions, draft angles and evaluation of lamination quality.

A microfluidic sub-critical water extraction instrument

Science.gov (United States)

Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita; Lee, Mike C.; Takano, Nobuyuki; Bao, Xiaoqi; Kutzer, Thomas C.; Grunthaner, Frank

2017-11-01

This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction. The extraction yield of the microfluidic SCWE chip process ranged from 50% compared to acid hydrolysis and 80%-100% compared to a benchtop microwave SCWE for low biomass samples.

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

International Nuclear Information System (INIS)

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

2011-01-01

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. (technical note)

Optimized fabrication protocols of microfluidic devices for X-ray analysis

KAUST Repository

Catalano, Rossella; Perozziello, Gerardo; Simone, Giuseppina; Candeloro, Patrizio; Gentile, Francesco T.; Coluccio, Maria Laura; Pardeo, Francesca; Burghammer, Manfred C.; Cuda, Giovanni; Riekel, Christian; Di Fabrizio, Enzo M.

2014-01-01

Microfluidics combined with X-ray scattering techniques allows probing conformational changes or assembly processes of biological materials. Our aim was to develop a highly X-ray transparent microfluidic cell for detecting small variations of X-ray

A microfluidic dialysis device for complex biological mixture SERS analysis

KAUST Repository

Perozziello, Gerardo; Candeloro, Patrizio; Gentile, Francesco T.; Coluccio, Maria Laura; Tallerico, Marco; De Grazia, Antonio; Nicastri, Annalisa; Perri, Angela Mena; Parrotta, Elvira; Pardeo, Francesca; Catalano, Rossella; Cuda, Giovanni; Di Fabrizio, Enzo M.

2015-01-01

In this paper, we present a microfluidic device fabricated with a simple and inexpensive process allowing rapid filtering of peptides from a complex mixture. The polymer microfluidic device can be used for sample preparation in biological

A zero-flow microfluidics for long-term cell culture and detection

Directory of Open Access Journals (Sweden)

Shengbo Sang

2015-04-01

Full Text Available A zero-flow microfluidic design is proposed in this paper, which can be used for long-term cell culture and detection, especially for a lab-on-chip integrated with a biosensor. It consists of two parts: a main microchannel; and a circle microchamber. The Finite Element Method (FEM was employed to predict the fluid transport properties for a minimum fluid flow disturbance. Some commonly used microfluidic structures were also analysed systematically to prove the designed structure. Then the designed microfluidics was fabricated. Based on the simulations and experiments, this design provides a continuous flow environment, with a relatively stable and low shear stress atmosphere, similar to a zero-flow environment. Furthermore, the nutrients maintaining cells’ normal growth can be taken into the chamber through the diffusion effect. It also proves that the microfluidics can realize long-term cell culture and detection. The application of the structure in the field of biological microelectromechenical systems (BioMEMS will provide a research foundation for microfluidic technology.

Advances in Microfluidic Platforms for Analyzing and Regulating Human Pluripotent Stem Cells

Science.gov (United States)

Qian, Tongcheng; Shusta, Eric V.; Palecek, Sean P.

2015-01-01

Microfluidic devices employ submillimeter length scale control of flow to achieve high-resolution spatial and temporal control over the microenvironment, providing powerful tools to elucidate mechanisms of human pluripotent stem cell (hPSC) regulation and to elicit desired hPSC fates. In addition, microfluidics allow control of paracrine and juxtracrine signaling, thereby enabling fabrication of microphysiological systems comprised of multiple cell types organized into organs-on-a-chip. Microfluidic cell culture systems can also be integrated with actuators and sensors, permitting construction of high-density arrays of cell-based biosensors for screening applications. This review describes recent advances in using microfluidics to understand mechanisms by which the microenvironment regulates hPSC fates and applications of microfluidics to realize the potential of hPSCs for in vitro modeling and screening applications. PMID:26313850

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

Science.gov (United States)

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.

Microfluidic-based Broadband Measurements of Fluid Permittivity and Permeability to 100 GHz

Science.gov (United States)

Little, Charles A. E.

This dissertation concerns the development of unique microfluidic microwave devices and associated microwave calibrations to quantitatively extract the broadband permittivity and permeability of fluids between 100 kHz and 110 GHz. The devices presented here consist of SU-8- and PDMS-based microfluidic channels integrated lithographically with coplanar waveguides (CPWs), measured via an external vector network analyzer (VNA). By applying our hybrid set of microwave calibrations to the raw data we extract distributed circuit parameters, representative of the electromagnetic response of the microfluidic channel. We then correlate these parameters to the permittivity and permeability of the fluid within the channels. We are primarily focused on developing devices, calibrations, and analyses to characterize various chemical and biological systems. The small fluid volumes and overall scale of our devices lends the technique to point-of-care blood and cell analysis, as well as to the analysis of high-value chemicals. Broadband microwave microfluidics is sensitive to three primary categories of phenomena: Ionic, dipolar, and magnetic resonances. All three can occur in complex fluids such as blood, proteins and particle suspensions. In order to make quantitative measurements, we need to be able to model and separate all three types of responses. Here we first measure saline solutions (NaCl and water) as an ideal system to better understanding both the ionic and dipolar response. Specifically, we are targeting the electrical double-layer (EDL) response, an ionic effect, which dominates over the intrinsic fluid response at lower frequencies. We have found that the EDL response for saline obeys a strict Debye-type relaxation model, the frequency response of which is dependent solely on the conductivity of the solution. To develop a better understanding of the magnetic response, we first measure magnetic nanoparticles; showing it is possible to detect the magnetic resonances of

A microfluidic dialysis device for complex biological mixture SERS analysis

KAUST Repository

Perozziello, Gerardo

2015-08-01

In this paper, we present a microfluidic device fabricated with a simple and inexpensive process allowing rapid filtering of peptides from a complex mixture. The polymer microfluidic device can be used for sample preparation in biological applications. The device is fabricated by micromilling and solvent assisted bonding, in which a microdialysis membrane (cut-off of 12-14 kDa) is sandwiched in between an upper and a bottom microfluidic chamber. An external frame connects the microfluidic device to external tubes, microvalves and syringe pumps. Bonding strength and interface sealing are pneumatically tested. Microfluidic protocols are also described by using the presented device to filter a sample composed of specific peptides (MW 1553.73 Da, at a concentration of 1.0 ng/μl) derived from the BRCA1 protein, a tumor-suppressor molecule which plays a pivotal role in the development of breast cancer, and albumin (MW 66.5 kDa, at a concentration of 35 μg/μl), the most represented protein in human plasma. The filtered samples coming out from the microfluidic device were subsequently deposited on a SERS (surface enhanced Raman scattering) substrate for further analysis by Raman spectroscopy. By using this approach, we were able to sort the small peptides from the bigger and highly concentrated protein albumin and to detect them by using a label-free technique at a resolution down to 1.0 ng/μl.

Microfluidics: an enabling screening technology for enhanced oil recovery (EOR).

Science.gov (United States)

Lifton, Victor A

2016-05-21

Oil production is a critical industrial process that affects the entire world population and any improvements in its efficiency while reducing its environmental impact are of utmost societal importance. The paper reviews recent applications of microfluidics and microtechnology to study processes of oil extraction and recovery. It shows that microfluidic devices can be useful tools in investigation and visualization of such processes used in the oil & gas industry as fluid propagation, flooding, fracturing, emulsification and many others. Critical macro-scale processes that define oil extraction and recovery are controlled by the micro-scale processes based on wetting, adhesion, surface tension, colloids and other concepts of microfluidics. A growing number of research efforts demonstrates that microfluidics is becoming, albeit slowly, an accepted methodology in this area. We propose several areas of development where implementation of microfluidics may bring about deeper understanding and hence better control over the processes of oil recovery based on fluid propagation, droplet generation, wettability control. Studies of processes such as hydraulic fracturing, sand particle propagation in porous networks, high throughput screening of chemicals (for example, emulsifiers and surfactants) in microfluidic devices that simulate oil reservoirs are proposed to improve our understanding of these complicated physico-chemical systems. We also discuss why methods of additive manufacturing (3D printing) should be evaluated for quick prototyping and modification of the three-dimensional structures replicating natural oil-bearing rock formations for studies accessible to a wider audience of researchers.

Predicting the behavior of microfluidic circuits made from discrete elements

Science.gov (United States)

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

2015-10-01

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

Predicting the behavior of microfluidic circuits made from discrete elements.

Science.gov (United States)

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

2015-10-30

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

3D-printed microfluidic chips with patterned, cell-laden hydrogel constructs.

Science.gov (United States)

Knowlton, Stephanie; Yu, Chu Hsiang; Ersoy, Fulya; Emadi, Sharareh; Khademhosseini, Ali; Tasoglu, Savas

2016-06-20

Three-dimensional (3D) printing offers potential to fabricate high-throughput and low-cost fabrication of microfluidic devices as a promising alternative to traditional techniques which enables efficient design iterations in the development stage. In this study, we demonstrate a single-step fabrication of a 3D transparent microfluidic chip using two alternative techniques: a stereolithography-based desktop 3D printer and a two-step fabrication using an industrial 3D printer based on polyjet technology. This method, compared to conventional fabrication using relatively expensive materials and labor-intensive processes, presents a low-cost, rapid prototyping technique to print functional 3D microfluidic chips. We enhance the capabilities of 3D-printed microfluidic devices by coupling 3D cell encapsulation and spatial patterning within photocrosslinkable gelatin methacryloyl (GelMA). The platform presented here serves as a 3D culture environment for long-term cell culture and growth. Furthermore, we have demonstrated the ability to print complex 3D microfluidic channels to create predictable and controllable fluid flow regimes. Here, we demonstrate the novel use of 3D-printed microfluidic chips as controllable 3D cell culture environments, advancing the applicability of 3D printing to engineering physiological systems for future applications in bioengineering.

Microfluidics' great promise for Biology - Microfluidics as a new engine for the molecular sciences

KAUST Repository

Kodzius, Rimantas

2010-06-04

History of the Life Sciences Origins of life Discoveries and instrumentation The power of genetic variation Diagnostics based on DNA/ protein variation Genomic scanning providers DNA sequencing companies Microfluidics story Commercial products available P

Microfluidic systems for stem cell-based neural tissue engineering.

Science.gov (United States)

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.

Microfluidic Liquid-Liquid Contactors

Energy Technology Data Exchange (ETDEWEB)

Mcculloch, Quinn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-07-25

This report describes progress made on the microfluidic contactor. A model was developed to predict its failure, a surrogate chemical system was selected to demonstrate mass transfer, and an all-optical system has been invented and implemented to monitor carryover and flowrates.

Microfluidic Adaptation of Density-Gradient Centrifugation for Isolation of Particles and Cells

Directory of Open Access Journals (Sweden)

Yuxi Sun

2017-08-01

Full Text Available Density-gradient centrifugation is a label-free approach that has been extensively used for cell separations. Though elegant, this process is time-consuming (>30 min, subjects cells to high levels of stress (>350 g and relies on user skill to enable fractionation of cells that layer as a narrow band between the density-gradient medium and platelet-rich plasma. We hypothesized that microfluidic adaptation of this technique could transform this process into a rapid fractionation approach where samples are separated in a continuous fashion while being exposed to lower levels of stress (<100 g for shorter durations of time (<3 min. To demonstrate proof-of-concept, we designed a microfluidic density-gradient centrifugation device and constructed a setup to introduce samples and medium like Ficoll in a continuous, pump-less fashion where cells and particles can be exposed to centrifugal force and separated via different outlets. Proof-of-concept studies using binary mixtures of low-density polystyrene beads (1.02 g/cm3 and high-density silicon dioxide beads (2.2 g/cm3 with Ficoll–Paque (1.06 g/cm3 show that separation is indeed feasible with >99% separation efficiency suggesting that this approach can be further adapted for separation of cells.

Fabrication of Three Dimensional Tissue Engineering Polydimethylsiloxane ( PDMS) Microporous Scaffolds Integrated in a Bioreactor Using a 3D Printed Water Dissolvable Sacrificial Mould

DEFF Research Database (Denmark)

Mohanty, Soumyaranjan; Mantis, Ioannis; Chetan, Aradhya Mallikarjunaiah

2015-01-01

We present a new scalable and general approach for manufacturing structured pores/channels in 3D polymer based scaffolds. The method involves 3D printing of a sacrificial polyvinyl alcohol (PVA) mould whose geometrical features are designed according to the required vascular channel network. Poly...

A centrifugal microfluidic platform for point-of-care diagnostic applications

CSIR Research Space (South Africa)

Hugo, S

2014-02-01

Full Text Available Microfluidic systems enable precise control over tiny volumes of fluid in a compact and low-cost form, thus providing the ideal platform on which to develop point-of-care diagnostic solutions. Centrifugal microfluidic systems, also referred...

Metallic nanomesh

Energy Technology Data Exchange (ETDEWEB)

Ren, Zhifeng; Sun, Tianyi; Guo, Chuanfei

2018-02-20

A transparent flexible nanomesh having at least one conductive element and sheet resistance less than 300.OMEGA./.quadrature. when stretched to a strain of 200% in at least one direction. The nanomesh is formed by depositing a sacrificial film, depositing, etching, and oxidizing a first metal layer on the film, etching the sacrificial film, depositing a second metal layer, and removing the first metal layer to form a nanomesh on the substrate.

Hysteresis in multiphase microfluidics at a T-junction.

Science.gov (United States)

Zagnoni, Michele; Anderson, Jamie; Cooper, Jonathan M

2010-06-15

Multiphase microfluidics offer a wide range of functionalities in the fields of fluid dynamics, biology, particle synthesis, and, more recently, also in logical computation. In this article, we describe the hysteresis of immiscible, multiphase flow obtained in hydrophilic, microfluidic systems at a T-junction. Stable and unstable state behaviors, in the form of segmented and parallel flow patterns of oil and water, were reliably produced, depending upon the history of the flow rates applied to the phases. The transition mechanisms between the two states were analyzed both experimentally and using numerical simulations, describing how the physical and fluid dynamic parameters influenced the hysteretic behavior of the flow. The characteristics of these multiphase systems render them suitable to be used as pressure comparators and also for the implementation of microfluidic logic operations.

Microfluidic Pumps Containing Teflon [Trademark] AF Diaphragms

Science.gov (United States)

Willis, Peter; White, Victor; Grunthaner, Frank; Ikeda, Mike; Mathies, Richard A.

2009-01-01

Microfluidic pumps and valves based on pneumatically actuated diaphragms made of Teflon AF polymers are being developed for incorporation into laboratory-on-a-chip devices that must perform well over temperature ranges wider than those of prior diaphragm-based microfluidic pumps and valves. Other potential applications include implanted biomedical microfluidic devices, wherein the biocompatability of Teflon AF polymers would be highly advantageous. These pumps and valves have been demonstrated to function stably after cycling through temperatures from -125 to 120 C. These pumps and valves are intended to be successors to similar prior pumps and valves containing diaphragms made of polydimethylsiloxane (PDMS) [commonly known as silicone rubber]. The PDMS-containing valves ae designed to function stably only within the temperature range from 5 to 80 C. Undesirably, PDMS membranes are somwehat porous and retain water. PDMS is especially unsuitable for use at temperatures below 0 C because the formation of ice crystals increases porosity and introduces microshear.

Microfluidic isotachophoresis: A review

Czech Academy of Sciences Publication Activity Database

Smejkal, P.; Bottenus, D.; Breadmore, M. C.; Guijt, R. M.; Ivory, C. F.; Foret, František; Macka, M.

2013-01-01

Roč. 34, č. 11 (2013), s. 1493-1509 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GAP301/11/2055 Institutional support: RVO:68081715 Keywords : chip * isotachophoresis * microfluidics * miniaturization Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.161, year: 2013

Disposable world-to-chip interface for digital microfluidics

Science.gov (United States)

Van Dam, R. Michael; Shah, Gaurav; Keng, Pei-Yuin

2017-05-16

The present disclosure sets forth incorporating microfluidic chips interfaces for use with digital microfluidic processes. Methods and devices according to the present disclosure utilize compact, integrated platforms that interface with a chip upstream and downstream of the reaction, as well as between intermediate reaction steps if needed. In some embodiments these interfaces are automated, including automation of a multiple reagent process. Various reagent delivery systems and methods are also disclosed.

Coalescence kinetics of oil-in-water emulsions studied with microfluidics

NARCIS (Netherlands)

Krebs, T.; Schroen, C.G.P.H.; Boom, R.M.

2013-01-01

We report the results of experiments on the coalescence dynamics in flowing oil-in-water emulsions using an integrated microfluidic device. The microfluidic circuit permits direct observation of shear-induced collisions and coalescence events between emulsion droplets. Three mineral oils with a

Thermal effects in microfluidics with thermal conductivity spatially modulated

Science.gov (United States)

Vargas Toro, Agustín.

2014-05-01

A heat transfer model on a microfluidic is resolved analytically. The model describes a fluid at rest between two parallel plates where each plate is maintained at a differentially specified temperature and the thermal conductivity of the microfluidic is spatially modulated. The heat transfer model in such micro-hydrostatic configuration is analytically resolved using the technique of the Laplace transform applying the Bromwich Integral and the Residue theorem. The temperature outline in the microfluidic is presented as an infinite series of Bessel functions. It is shown that the result for the thermal conductivity spatially modulated has as a particular case the solution when the thermal conductivity is spatially constant. All computations were performed using the computer algebra software Maple. It is claimed that the analytical obtained results are important for the design of nanoscale devices with applications in biotechnology. Furthermore, it is suggested some future research lines such as the study of the heat transfer model in a microfluidic resting between coaxial cylinders with radially modulated thermal conductivity in order to achieve future developments in this area.

Hybrid Integrated Silicon Microfluidic Platform for Fluorescence Based Biodetection

Directory of Open Access Journals (Sweden)

André Darveau

2007-09-01

Full Text Available The desideratum to develop a fully integrated Lab-on-a-chip device capable ofrapid specimen detection for high throughput in-situ biomedical diagnoses and Point-of-Care testing applications has called for the integration of some of the novel technologiessuch as the microfluidics, microphotonics, immunoproteomics and Micro ElectroMechanical Systems (MEMS. In the present work, a silicon based microfluidic device hasbeen developed for carrying out fluorescence based immunoassay. By hybrid attachment ofthe microfluidic device with a Spectrometer-on-chip, the feasibility of synthesizing anintegrated Lab-on-a-chip type device for fluorescence based biosensing has beendemonstrated. Biodetection using the microfluidic device has been carried out usingantigen sheep IgG and Alexafluor-647 tagged antibody particles and the experimentalresults prove that silicon is a compatible material for the present application given thevarious advantages it offers such as cost-effectiveness, ease of bulk microfabrication,superior surface affinity to biomolecules, ease of disposability of the device etc., and is thussuitable for fabricating Lab-on-a-chip type devices.

IFSA: a microfluidic chip-platform for frit-based immunoassay protocols

Science.gov (United States)

Hlawatsch, Nadine; Bangert, Michael; Miethe, Peter; Becker, Holger; Gärtner, Claudia

2013-03-01

Point-of-care diagnostics (POC) is one of the key application fields for lab-on-a-chip devices. While in recent years much of the work has concentrated on integrating complex molecular diagnostic assays onto a microfluidic device, there is a need to also put comparatively simple immunoassay-type protocols on a microfluidic platform. In this paper, we present the development of a microfluidic cartridge using an immunofiltration approach. In this method, the sandwich immunoassay takes place in a porous frit on which the antibodies have immobilized. The device is designed to be able to handle three samples in parallel and up to four analytical targets per sample. In order to meet the critical cost targets for the diagnostic market, the microfluidic chip has been designed and manufactured using high-volume manufacturing technologies in mind. Validation experiments show comparable sensitivities in comparison with conventional immunofiltration kits.

Recent microfluidic devices for studying gamete and embryo biomechanics.

Science.gov (United States)

Lai, David; Takayama, Shuichi; Smith, Gary D

2015-06-25

The technical challenges of biomechanic research such as single cell analysis at a high monetary cost, labor, and time for just a small number of measurements is a good match to the strengths of microfluidic devices. New scientific discoveries in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of clinical practice in assisted reproduction. The following review will highlight some recent microfluidic devices tailored for gamete and embryo biomechanics where biomimicry arises as a major theme of microfluidic device design and function, and the application of fundamental biomechanic principles are used to improve outcomes of cryopreservation. Copyright © 2015 Elsevier Ltd. All rights reserved.

The negative-differential-resistance (NDR) mechanism of a hydroelastic microfluidic oscillator

International Nuclear Information System (INIS)

Xia, H M; Wu, J W; Wang, Z P

2017-01-01

A microfluidic oscillator is of interest because it converts a stable laminar flow to oscillatory flow, especially in view of the fact that turbulence is typically absent in miniaturized fluidic devices. One important design approach is to utilize hydroelastic effect-induced autonomous oscillations to modify the flow, so to reduce the reliance on external controllers. However, as complex fluid-structure interactions are involved, the prediction of its mechanism is rather challenging. Here, we present a simple equivalent circuit model and investigate the negative-differential-resistance (NDR) mechanism of a hydroelastic microfluidic oscillator. We show that a variety of complex flow behaviors including the onset of oscillation, formation of different oscillation patterns, collapse of the channel, etc can be well explained by this model. It provides a generic approach for construction of microfluidic NDR oscillators, following which a new design is also proposed. Relevant findings give more insights into the hydroelastic instability problems in microfluidics, and enrich the study of microfluidic flow control devices based on the electric circuit theory. (paper)

Neural Stem Cell Differentiation Using Microfluidic Device-Generated Growth Factor Gradient.

Science.gov (United States)

Kim, Ji Hyeon; Sim, Jiyeon; Kim, Hyun-Jung

2018-04-11

Neural stem cells (NSCs) have the ability to self-renew and differentiate into multiple nervous system cell types. During embryonic development, the concentrations of soluble biological molecules have a critical role in controlling cell proliferation, migration, differentiation and apoptosis. In an effort to find optimal culture conditions for the generation of desired cell types in vitro , we used a microfluidic chip-generated growth factor gradient system. In the current study, NSCs in the microfluidic device remained healthy during the entire period of cell culture, and proliferated and differentiated in response to the concentration gradient of growth factors (epithermal growth factor and basic fibroblast growth factor). We also showed that overexpression of ASCL1 in NSCs increased neuronal differentiation depending on the concentration gradient of growth factors generated in the microfluidic gradient chip. The microfluidic system allowed us to study concentration-dependent effects of growth factors within a single device, while a traditional system requires multiple independent cultures using fixed growth factor concentrations. Our study suggests that the microfluidic gradient-generating chip is a powerful tool for determining the optimal culture conditions.

Encapsulation of high temperature molten salts

Science.gov (United States)

Oxley, James D.; Mathur, Anoop Kumar

2017-05-16

The present disclosure relates to a method of encapsulating microcapsules containing relatively high temperature phase change materials and the microcapsules so produced. The microcapsules are coated with an inorganic binder, film former and an inorganic filler. The microcapsules may include a sacrificial layer that is disposed between the particle and the coating. The microcapsules may also include an inner coating layer, sacrificial layer and outer coating layer. The microcapsules are particularly useful for thermal energy storage in connection with, e.g., heat collected from concentrating solar collectors.

Design Considerations for Integration of Terahertz Time-Domain Spectroscopy in Microfluidic Platforms

Directory of Open Access Journals (Sweden)

Rasha Al-Hujazy

2018-03-01

Full Text Available Microfluidic platforms have received much attention in recent years. In particular, there is interest in combining spectroscopy with microfluidic platforms. This work investigates the integration of microfluidic platforms and terahertz time-domain spectroscopy (THz-TDS systems. A semiclassical computational model is used to simulate the emission of THz radiation from a GaAs photoconductive THz emitter. This model incorporates white noise with increasing noise amplitude (corresponding to decreasing dynamic range values. White noise is selected over other noise due to its contributions in THz-TDS systems. The results from this semiclassical computational model, in combination with defined sample thicknesses, can provide the maximum measurable absorption coefficient for a microfluidic-based THz-TDS system. The maximum measurable frequencies for such systems can be extracted through the relationship between the maximum measurable absorption coefficient and the absorption coefficient for representative biofluids. The sample thickness of the microfluidic platform and the dynamic range of the THz-TDS system play a role in defining the maximum measurable frequency for microfluidic-based THz-TDS systems. The results of this work serve as a design tool for the development of such systems.

Visual Estimation of Bacterial Growth Level in Microfluidic Culture Systems.

Science.gov (United States)

Kim, Kyukwang; Kim, Seunggyu; Jeon, Jessie S

2018-02-03

Microfluidic devices are an emerging platform for a variety of experiments involving bacterial cell culture, and has advantages including cost and convenience. One inevitable step during bacterial cell culture is the measurement of cell concentration in the channel. The optical density measurement technique is generally used for bacterial growth estimation, but it is not applicable to microfluidic devices due to the small sample volumes in microfluidics. Alternately, cell counting or colony-forming unit methods may be applied, but these do not work in situ; nor do these methods show measurement results immediately. To this end, we present a new vision-based method to estimate the growth level of the bacteria in microfluidic channels. We use Fast Fourier transform (FFT) to detect the frequency level change of the microscopic image, focusing on the fact that the microscopic image becomes rough as the number of cells in the field of view increases, adding high frequencies to the spectrum of the image. Two types of microfluidic devices are used to culture bacteria in liquid and agar gel medium, and time-lapsed images are captured. The images obtained are analyzed using FFT, resulting in an increase in high-frequency noise proportional to the time passed. Furthermore, we apply the developed method in the microfluidic antibiotics susceptibility test by recognizing the regional concentration change of the bacteria that are cultured in the antibiotics gradient. Finally, a deep learning-based data regression is performed on the data obtained by the proposed vision-based method for robust reporting of data.

Visual Estimation of Bacterial Growth Level in Microfluidic Culture Systems

Directory of Open Access Journals (Sweden)

Kyukwang Kim

2018-02-01

Full Text Available Microfluidic devices are an emerging platform for a variety of experiments involving bacterial cell culture, and has advantages including cost and convenience. One inevitable step during bacterial cell culture is the measurement of cell concentration in the channel. The optical density measurement technique is generally used for bacterial growth estimation, but it is not applicable to microfluidic devices due to the small sample volumes in microfluidics. Alternately, cell counting or colony-forming unit methods may be applied, but these do not work in situ; nor do these methods show measurement results immediately. To this end, we present a new vision-based method to estimate the growth level of the bacteria in microfluidic channels. We use Fast Fourier transform (FFT to detect the frequency level change of the microscopic image, focusing on the fact that the microscopic image becomes rough as the number of cells in the field of view increases, adding high frequencies to the spectrum of the image. Two types of microfluidic devices are used to culture bacteria in liquid and agar gel medium, and time-lapsed images are captured. The images obtained are analyzed using FFT, resulting in an increase in high-frequency noise proportional to the time passed. Furthermore, we apply the developed method in the microfluidic antibiotics susceptibility test by recognizing the regional concentration change of the bacteria that are cultured in the antibiotics gradient. Finally, a deep learning-based data regression is performed on the data obtained by the proposed vision-based method for robust reporting of data.

Microfluidic device for acoustic cell lysis

Science.gov (United States)

Branch, Darren W.; Cooley, Erika Jane; Smith, Gennifer Tanabe; James, Conrad D.; McClain, Jaime L.

2015-08-04

A microfluidic acoustic-based cell lysing device that can be integrated with on-chip nucleic acid extraction. Using a bulk acoustic wave (BAW) transducer array, acoustic waves can be coupled into microfluidic cartridges resulting in the lysis of cells contained therein by localized acoustic pressure. Cellular materials can then be extracted from the lysed cells. For example, nucleic acids can be extracted from the lysate using silica-based sol-gel filled microchannels, nucleic acid binding magnetic beads, or Nafion-coated electrodes. Integration of cell lysis and nucleic acid extraction on-chip enables a small, portable system that allows for rapid analysis in the field.

Micro-Fluidic Device for Drug Delivery

Science.gov (United States)

Beebe, David J. (Inventor); MacDonald, Michael J. (Inventor); Eddington, David T. (Inventor); Mensing, Glennys A. (Inventor)

2014-01-01

A microfluidic device is provided for delivering a drug to an individual. The microfluidic device includes a body that defines a reservoir for receiving the drug therein. A valve interconnects the reservoir to an output needle that is insertable into the skin of an individual. A pressure source urges the drug from the reservoir toward the needle. The valve is movable between a closed position preventing the flow of the drug from the reservoir to the output needle and an open position allowing for the flow of the drug from the reservoir to the output needle in response to a predetermined condition in the physiological fluids of the individual.

Field effect control of electro-osmotic flow in microfluidic networks

NARCIS (Netherlands)

van der Wouden, E.J.

2006-01-01

This thesis describes the development of a Field Effect Flow Control (FEFC) system for the control of Electro Osmotic Flow (EOF) in microfluidic networks. For this several aspects of FEFC have been reviewed and a process to fabricate microfluidic channels with integrated electrodes has been

Application-specific fault-tolerant architecture synthesis for digital microfluidic biochips

DEFF Research Database (Denmark)

Alistar, Mirela; Pop, Paul; Madsen, Jan

2013-01-01

, but as discrete droplets on an array of electrodes. Microfluidic operations, such as transport, mixing, split, are performed on this array by routing the corresponding droplets on a series of electrodes. Researchers have proposed several approaches for the synthesis of digital microfluidic biochips. All previous...

Interconnection blocks: a method for providing reusable, rapid, multiple, aligned and planar microfluidic interconnections

DEFF Research Database (Denmark)

Sabourin, David; Snakenborg, Detlef; Dufva, Hans Martin

2009-01-01

In this paper a method is presented for creating 'interconnection blocks' that are re-usable and provide multiple, aligned and planar microfluidic interconnections. Interconnection blocks made from polydimethylsiloxane allow rapid testing of microfluidic chips and unobstructed microfluidic observ...

Enzyme detection by microfluidics

DEFF Research Database (Denmark)

2013-01-01

Microfluidic-implemented methods of detecting an enzyme, in particular a DNA-modifying enzyme, are provided, as well as methods for detecting a cell, or a microorganism expressing said enzyme. The enzyme is detected by providing a nucleic acid substrate, which is specifically targeted...... by that enzyme...

X-ray transparent Microfluidics for Protein Crystallization and Biomineralization

Science.gov (United States)

Opathalage, Achini

Protein crystallization demands the fundamental understanding of nucleation and applying techniques to find the optimal conditions to achieve the kinetic pathway for a large and defect free crystal. Classical nucleation theory predicts that the nucleation occurs at high supersaturation conditions. In this dissertation we sought out to develop techniques to attain optimal supersaturation profile to a large defect free crystal and subject it to in-situ X-ray diffraction using microfluidics. We have developed an emulsion-based serial crystallographic technology in nanolitre-sized droplets of protein solution encapsulated in to nucleate one crystal per drop. Diffraction data are measured, one crystal at a time, from a series of room temperature crystals stored on an X-ray semi-transparent microfluidic chip, and a 93% complete data set is obtained by merging single diffraction frames taken from different un-oriented crystals. As proof of concept, the structure of Glucose Isomerase was solved to 2.1 A. We have developed a suite of X-ray semi-transparent micrfluidic devices which enables; controlled evaporation as a method of increasing supersaturation and manipulating the phase space of proteins and small molecules. We exploited the inherently high water permeability of the thin X-ray semi-transparent devices as a mean of increasing the supersaturation by controlling the evaporation. We fabricated the X-ray semi-transparent version of the PhaseChip with a thin PDMS membrane by which the storage and the reservoir layers are separated, and studies the phase transition of amorphous CaCO3.

Automated quantitative cytological analysis using portable microfluidic microscopy.

Science.gov (United States)

Jagannadh, Veerendra Kalyan; Murthy, Rashmi Sreeramachandra; Srinivasan, Rajesh; Gorthi, Sai Siva

2016-06-01

In this article, a portable microfluidic microscopy based approach for automated cytological investigations is presented. Inexpensive optical and electronic components have been used to construct a simple microfluidic microscopy system. In contrast to the conventional slide-based methods, the presented method employs microfluidics to enable automated sample handling and image acquisition. The approach involves the use of simple in-suspension staining and automated image acquisition to enable quantitative cytological analysis of samples. The applicability of the presented approach to research in cellular biology is shown by performing an automated cell viability assessment on a given population of yeast cells. Further, the relevance of the presented approach to clinical diagnosis and prognosis has been demonstrated by performing detection and differential assessment of malaria infection in a given sample. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective distribution of enzymes in a microfluidic reactor

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Pereira Rosinha Grundtvig, Ines; Krühne, Ulrich

Off stoichiometric thiol-ene mixtures are well suited for preparation of microfluidic devices with highly functional surfaces. Here a two stage process employing first thiol-ene chemistry (TEC) to prepare two opposite parts of a microfluidic system with a 30x30 mm reactor and subsequently a thiol......-epoxy bonding was used to prepare a fully sealed microfluidic system. The reactor was surface functionalized in-situ with allyl glycidyl ether in different patterns (half-reactor, full-reactor, checkerboard structures) on the surface to provide a controlled distribution of epoxides. The method additionally...... enables the selective immobilization on either top-side or bottom-side or both sides of the reactor. Thereafter horseradish peroxidase was immobilized on the surface and activity tests illustrated how this distribution of the enzyme on the surface could be used to optimize the activity of the enzyme...

System-level modeling and simulation of the cell culture microfluidic biochip ProCell

DEFF Research Database (Denmark)

Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan

2010-01-01

Microfluidic biochips offer a promising alternative to a conventional biochemical laboratory. There are two technologies for the microfluidic biochips: droplet-based and flow-based. In this paper we are interested in flow-based microfluidic biochips, where the liquid flows continuously through pre......-defined micro-channels using valves and pumps. We present an approach to the system-level modeling and simulation of a cell culture microfluidic biochip called ProCell, Programmable Cell Culture Chip. ProCell contains a cell culture chamber, which is envisioned to run 256 simultaneous experiments (viewed...

Facile fabrication of microfluidic surface-enhanced Raman scattering devices via lift-up lithography

Science.gov (United States)

Wu, Yuanzi; Jiang, Ye; Zheng, Xiaoshan; Jia, Shasha; Zhu, Zhi; Ren, Bin; Ma, Hongwei

2018-04-01

We describe a facile and low-cost approach for a flexibly integrated surface-enhanced Raman scattering (SERS) substrate in microfluidic chips. Briefly, a SERS substrate was fabricated by the electrostatic assembling of gold nanoparticles, and shaped into designed patterns by subsequent lift-up soft lithography. The SERS micro-pattern could be further integrated within microfluidic channels conveniently. The resulting microfluidic SERS chip allowed ultrasensitive in situ SERS monitoring from the transparent glass window. With its advantages in simplicity, functionality and cost-effectiveness, this method could be readily expanded into optical microfluidic fabrication for biochemical applications.

Integrated Microfluidic Gas Sensors for Water Monitoring

Science.gov (United States)

Zhu, L.; Sniadecki, N.; DeVoe, D. L.; Beamesderfer, M.; Semancik, S.; DeVoe, D. L.

2003-01-01

A silicon-based microhotplate tin oxide (SnO2) gas sensor integrated into a polymer-based microfluidic system for monitoring of contaminants in water systems is presented. This device is designed to sample a water source, control the sample vapor pressure within a microchannel using integrated resistive heaters, and direct the vapor past the integrated gas sensor for analysis. The sensor platform takes advantage of novel technology allowing direct integration of discrete silicon chips into a larger polymer microfluidic substrate, including seamless fluidic and electrical interconnects between the substrate and silicon chip.

Diffusion dynamics in micro-fluidic dye lasers

DEFF Research Database (Denmark)

Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Niels Asger

2007-01-01

We have investigated the bleaching dynamics that occur in opto-fluidic dye lasers, where the liquid laser dye in a channel is locally bleached due to optical pumping. Our studies suggest that for micro-fluidic devices, the dye bleaching may be compensated through diffusion of dye molecules alone....... By relying on diffusion rather than convection to generate the necessary dye replenishment, our observation potentially allows for a significant simplification of opto-fluidic dye laser device layouts, omitting the need for cumbersome and costly external fluidic handling or on-chip micro-fluidic pumping...

Droplet-based microfluidic method for synthesis of microparticles

CSIR Research Space (South Africa)

Mbanjwa, MB

2012-10-01

Full Text Available Droplet-based microfluidics has, in recent years, received increased attention as an important tool for performing numerous methods in modern day chemistry and biology such as the synthesis of hydrogel microparticles. Hydrogels have been used in many..., in recent years, received increased attention as an important tool for performing numerous methods in modern day chemistry and biology, such as synthesis of hydrogel microparticles. CONCLUSION AND OUTLOOK The droplet-based microfluidic method offers...

Microfluidic-assisted fabrication of flexible and location traceable organo-motor.

Science.gov (United States)

Seo, Kyoung Duck; Kwak, Byung Kook; Sanchez, Samuel; Kim, Dong Sung

2015-04-01

In this paper, we fabricate a flexible and location traceable micromotor, called organo-motor, assisted by microfluidic devices and with high throughput. The organo-motors are composed of organic hydrogel material, poly (ethylene glycol) diacrylate (PEGDA), which can provide the flexibility of their structure. For spatial and temporal traceability of the organo-motors under magnetic resonance imaging (MRI), superparamagnetic iron oxide nanoparticles (SPION; Fe3O4) were incorporated into the PEGDA microhydrogels. Furthermore, a thin layer of platinum (Pt) was deposited onto one side of the SPION-PEGDA microhydrogels providing geometrical asymmetry and catalytic propulsion in aqueous fluids containing hydrogen peroxide solution, H2O2. Furthermore, the motion of the organo-motor was controlled by a small external magnet enabled by the presence of SPION in the motor architecture.

Isolation of cancer cells by "in situ" microfluidic biofunctionalization protocols

KAUST Repository

De Vitis, Stefania; Matarise, Giuseppina; Pardeo, Francesca; Catalano, Rossella; Malara, Natalia Maria; Trunzo, Valentina; Tallerico, Rossana; Gentile, Francesco T.; Candeloro, Patrizio; Coluccio, Maria Laura; Massaro, Alessandro S.; Viglietto, Giuseppe; Carbone, Ennio; Kutter, Jö rg Peter; Perozziello, Gerardo; Di Fabrizio, Enzo M.

2014-01-01

The aim of this work is the development of a microfluidic immunosensor for the immobilization of cancer cells and their separation from healthy cells by using "in situ" microfluidic biofunctionalization protocols. These protocols allow to link antibodies on microfluidic device surfaces and can be used to study the interaction between cell membrane and biomolecules. Moreover they allow to perform analysis with high processing speed, small quantity of reagents and samples, short reaction times and low production costs. In this work the developed protocols were used in microfluidic devices for the isolation of cancer cells in heterogeneous blood samples by exploiting the binding of specific antibody to an adhesion protein (EpCAM), overexpressed on the tumor cell membranes. The presented biofunctionalization protocols can be performed right before running the experiment: this allows to have a flexible platform where biomolecules of interest can be linked on the device surface according to the user's needs. © 2014 Elsevier B.V. All rights reserved.

Synthesis of hexagonal gold nanoparticles using a microfluidic reaction system

International Nuclear Information System (INIS)

Weng, Chen-Hsun; Lee, Gwo-Bin; Huang, Chih-Chia; Yeh, Chen-Sheng; Lei, Huan-Yao

2008-01-01

A new microfluidic reaction system capable of mixing, transporting and reacting is developed for the synthesis of gold nanoparticles. It allows for a rapid and a cost-effective approach to accelerate the synthesis of gold nanoparticles. The microfluidic reaction chip is made from micro-electro-mechanical-system technologies which integrate a micro-mixer, micro-pumps, a micro-valve, micro-heaters and a micro temperature sensor on a single chip. Successful synthesis of dispersed gold nanoparticles has been demonstrated within a shorter period of time, as compared to traditional methods. It is experimentally found that precise control of the mixing/heating time for gold salts and reducing agents plays an essential role in the synthesis of gold nanoparticles. The growth process of hexagonal gold nanoparticles by a thermal aqueous approach is also systematically studied by using the same microfluidic reaction system. The development of the microfluidic reaction system could be promising for the synthesis of functional nanoparticles for future biomedical applications

Skin Diseases Modeling using Combined Tissue Engineering and Microfluidic Technologies.

Science.gov (United States)

Mohammadi, Mohammad Hossein; Heidary Araghi, Behnaz; Beydaghi, Vahid; Geraili, Armin; Moradi, Farshid; Jafari, Parya; Janmaleki, Mohsen; Valente, Karolina Papera; Akbari, Mohsen; Sanati-Nezhad, Amir

2016-10-01

In recent years, both tissue engineering and microfluidics have significantly contributed in engineering of in vitro skin substitutes to test the penetration of chemicals or to replace damaged skins. Organ-on-chip platforms have been recently inspired by the integration of microfluidics and biomaterials in order to develop physiologically relevant disease models. However, the application of organ-on-chip on the development of skin disease models is still limited and needs to be further developed. The impact of tissue engineering, biomaterials and microfluidic platforms on the development of skin grafts and biomimetic in vitro skin models is reviewed. The integration of tissue engineering and microfluidics for the development of biomimetic skin-on-chip platforms is further discussed, not only to improve the performance of present skin models, but also for the development of novel skin disease platforms for drug screening processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isolation of cancer cells by "in situ" microfluidic biofunctionalization protocols

KAUST Repository

De Vitis, Stefania

2014-07-01

The aim of this work is the development of a microfluidic immunosensor for the immobilization of cancer cells and their separation from healthy cells by using "in situ" microfluidic biofunctionalization protocols. These protocols allow to link antibodies on microfluidic device surfaces and can be used to study the interaction between cell membrane and biomolecules. Moreover they allow to perform analysis with high processing speed, small quantity of reagents and samples, short reaction times and low production costs. In this work the developed protocols were used in microfluidic devices for the isolation of cancer cells in heterogeneous blood samples by exploiting the binding of specific antibody to an adhesion protein (EpCAM), overexpressed on the tumor cell membranes. The presented biofunctionalization protocols can be performed right before running the experiment: this allows to have a flexible platform where biomolecules of interest can be linked on the device surface according to the user\\'s needs. © 2014 Elsevier B.V. All rights reserved.

Fabricating a multi-level barrier-integrated microfluidic device using grey-scale photolithography

International Nuclear Information System (INIS)

Nam, Yoonkwang; Kim, Minseok; Kim, Taesung

2013-01-01

Most polymer-replica-based microfluidic devices are mainly fabricated by using standard soft-lithography technology so that multi-level masters (MLMs) require multiple spin-coatings, mask alignments, exposures, developments, and bakings. In this paper, we describe a simple method for fabricating MLMs for planar microfluidic channels with multi-level barriers (MLBs). A single photomask is necessary for standard photolithography technology to create a polydimethylsiloxane grey-scale photomask (PGSP), which adjusts the total amount of UV absorption in a negative-tone photoresist via a wide range of dye concentrations. Since the PGSP in turn adjusts the degree of cross-linking of the photoresist, this method enables the fabrication of MLMs for an MLB-integrated microfluidic device. Since the PGSP-based soft-lithography technology provides a simple but powerful fabrication method for MLBs in a microfluidic device, we believe that the fabrication method can be widely used for micro total analysis systems that benefit from MLBs. We demonstrate an MLB-integrated microfluidic device that can separate microparticles. (paper)

Microfluidics for medical applications

NARCIS (Netherlands)

van den Berg, Albert; van den Berg, A.; Segerink, L.I.; Segerink, Loes Irene; Unknown, [Unknown

2015-01-01

Lab-on-a-chip devices for point of care diagnostics have been present in clinics for several years now. Alongside their continual development, research is underway to bring the organs and tissue on-a-chip to the patient, amongst other medical applications of microfluidics. This book provides the

Numerical Optimization in Microfluidics

DEFF Research Database (Denmark)

Jensen, Kristian Ejlebjærg

2017-01-01

Numerical modelling can illuminate the working mechanism and limitations of microfluidic devices. Such insights are useful in their own right, but one can take advantage of numerical modelling in a systematic way using numerical optimization. In this chapter we will discuss when and how numerical...... optimization is best used....

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

Science.gov (United States)

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

2008-10-01

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.

Development of a Microfluidic Platform to Analyze Evolution of Programmed Bacterial Death

Science.gov (United States)

2015-12-20

droplet-based microfluidic technology to generate population ‘bottleneck’. This platform will serve as a critical foundation for our long-term goal to...Final Report: Development of a Microfluidic Platform to Analyze Evolution of Programmed Bacterial Death The views, opinions and/or findings contained...Triangle Park, NC 27709-2211 Microfluidics , systems biology REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM

Bioactive gyroid scaffolds formed by sacrificial templating of nanocellulose and nanochitin hydrogels as instructive platforms for biomimetic tissue engineering.

Science.gov (United States)

Torres-Rendon, Jose Guillermo; Femmer, Tim; De Laporte, Laura; Tigges, Thomas; Rahimi, Khosrow; Gremse, Felix; Zafarnia, Sara; Lederle, Wiltrud; Ifuku, Shinsuke; Wessling, Matthias; Hardy, John G; Walther, Andreas

2015-05-20

A sacrificial templating process using lithographically printed minimal surface structures allows complex de novo geo-metries of delicate hydrogel materials. The hydrogel scaffolds based on cellulose and chitin nanofibrils show differences in terms of attachment of human mesenchymal stem cells, and allow their differentiation into osteogenic outcomes. The approach here serves as a first example toward designer hydrogel scaffolds viable for biomimetic tissue engineering. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface texture change on-demand and microfluidic devices based on thickness mode actuation of dielectric elastomer actuators (DEAs)

Science.gov (United States)

Ankit, Ankit; Nguyen, Anh Chien; Mathews, Nripan

2017-04-01

Tactile feedback devices and microfluidic devices have huge significance in strengthening the area of robotics, human machine interaction and low cost healthcare. Dielectric Elastomer Actuators (DEAs) are an attractive alternative for both the areas; offering the advantage of low cost and simplistic fabrication in addition to the high actuation strains. The inplane deformations produced by the DEAs can be used to produce out-of-plane deformations by what is known as the thickness mode actuation of DEAs. The thickness mode actuation is achieved by adhering a soft passive layer to the DEA. This enables a wide area of applications in tactile applications without the need of complex systems and multiple actuators. But the thickness mode actuation has not been explored enough to understand how the deformations can be improved without altering the material properties; which is often accompanied with increased cost and a trade off with other closely associated material properties. We have shown the effect of dimensions of active region and non-active region in manipulating the out-of-plane deformation. Making use of this, we have been able to demonstrate large area devices and complex patterns on the passive top layer for the surface texture change on-demand applications. We have also been able to demonstrate on-demand microfluidic channels and micro-chambers without the need of actually fabricating the channels; which is a cost incurring and cumbersome process.

Transforming nanomedicine manufacturing toward Quality by Design and microfluidics

DEFF Research Database (Denmark)

Colombo, Stefano; Beck-Broichsitter, Moritz; Bøtker, Johan Peter

2018-01-01

-oriented manufacturing of pharmaceuticals has undergone an unprecedented change toward process and product development interaction. In this context, Quality by Design (QbD) aims to integrate product and process development resulting in an increased number of product applications to regulatory agencies and stronger...... proprietary defense strategies of process-based products. Although QbD can be applied to essentially any production approach, microfluidic production offers particular opportunities for QbD-based manufacturing of nanopharmaceuticals. Microfluidics provides unique design flexibility, process control...... and parameter predictability, and also offers ample opportunities for modular production setups, allowing process feedback for continuously operating production and process control. The present review aims at outlining emerging opportunities in the synergistic implementation of QbD strategies and microfluidic...

Synthesis of Digital Microfluidic Biochips with Reconfigurable Operation Execution

DEFF Research Database (Denmark)

Maftei, Elena

several real-life case studies and synthetic benchmarks. The experiments show that by considering the dynamically reconfigurable nature of microfluidic operations, significant improvements can be obtained, decreasing the biochemical application completion times, reducing thus the biochip area...... of electrodes. The main objective of this thesis is to develop top-down synthesis techniques for digital microfluidic biochips. So far, researchers have assumed that operations are executing on virtual modules of rectangular shape, formed by grouping adjacent electrodes, and which have a fixed placement...... on the microfluidic array. However, operations can actually execute by routing the droplets on any sequence of electrodes on the biochip. Thus, we have proposed a routing-based model of operation execution, and we have developed several associated synthesis approaches, which progressively relax the assumption...

Methods of making microfluidic devices

KAUST Repository

Buttner, Ulrich; Mashraei, Yousof; Agambayev, Sumeyra; Salama, Khaled N.

2017-01-01

Microfluidics has advanced in terms of designs and structures, however, fabrication methods are either time consuming or expensive to produce, in terms of the facilities and equipment needed. A fast and economically viable method is provided

Spintronic microfluidic platform for biomedical and environmental applications

Science.gov (United States)

Cardoso, F. A.; Martins, V. C.; Fonseca, L. P.; Germano, J.; Sousa, L. A.; Piedade, M. S.; Freitas, P. P.

2010-09-01

Faster, more sensitive and easy to operate biosensing devices still are a need at important areas such as biomedical diagnostics, food control and environmental monitoring. Recently, spintronic-devices have emerged as a promising alternative to the existent technologies [1-3]. A number of advantages, namely high sensitivity, easy integration, miniaturization, scalability, robustness and low cost make these devices potentially capable of responding to the existent technological need. In parallel, the field of microfluidics has shown great advances [4]. Microfluidic systems allow the analysis of small sample volumes (from micro- down to pico-liters), often by automate sample processing with the ability to integrate several steps into a single device (analyte amplification, concentration, separation and/or labeling), all in a reduced assay time (minutes to hours) and affordable cost. The merging of these two technologies, magnetoresistive biochips and microfluidics, will enable the development of highly competitive devices. This work reports the integration of a magnetoresistive biochip with a microfluidic system inside a portable and autonomous electronic platform aiming for a fully integrated device. A microfluidic structure fabricated in polydimethylsiloxane with dimensions of W: 0.5mm, H: 0.1mm, L: 10mm, associated to a mechanical system to align and seal the channel by pressure is presented (Fig. 1) [5]. The goal is to perform sample loading and transportation over the chip and simultaneously control the stringency and uniformity of the wash-out process. The biochip output is acquired by an electronic microsystem incorporating the circuitry to control, address and read-out the 30 spin-valve sensors sequentially (Fig. 1) [2]. This platform is being applied to the detection of water-borne microbial pathogens (e.g. Salmonella and Escherichia coli) and genetic diseases diagnosis (e.g. cystic fibrosis) through DNA hybridization assays. Open chamber measurements were

Simple Check Valves for Microfluidic Devices

Science.gov (United States)

Willis, Peter A.; Greer, Harold F.; Smith, J. Anthony

2010-01-01

A simple design concept for check valves has been adopted for microfluidic devices that consist mostly of (1) deformable fluorocarbon polymer membranes sandwiched between (2) borosilicate float glass wafers into which channels, valve seats, and holes have been etched. The first microfluidic devices in which these check valves are intended to be used are micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. In this application, it will be necessary to store some liquid samples in reservoirs in the devices for subsequent laboratory analysis, and check valves are needed to prevent cross-contamination of the samples. The simple check-valve design concept is also applicable to other microfluidic devices and to fluidic devices in general. These check valves are simplified microscopic versions of conventional rubber- flap check valves that are parts of numerous industrial and consumer products. These check valves are fabricated, not as separate components, but as integral parts of microfluidic devices. A check valve according to this concept consists of suitably shaped portions of a deformable membrane and the two glass wafers between which the membrane is sandwiched (see figure). The valve flap is formed by making an approximately semicircular cut in the membrane. The flap is centered over a hole in the lower glass wafer, through which hole the liquid in question is intended to flow upward into a wider hole, channel, or reservoir in the upper glass wafer. The radius of the cut exceeds the radius of the hole by an amount large enough to prevent settling of the flap into the hole. As in a conventional rubber-flap check valve, back pressure in the liquid pushes the flap against the valve seat (in this case, the valve seat is the adjacent surface of the lower glass wafer), thereby forming a seal that prevents backflow.

Sperm quality assessment via separation and sedimentation in a microfluidic device.

Science.gov (United States)

Chen, Chang-Yu; Chiang, Tsun-Chao; Lin, Cheng-Ming; Lin, Shu-Sheng; Jong, De-Shien; Tsai, Vincent F-S; Hsieh, Ju-Ton; Wo, Andrew M

2013-09-07

A major reason for infertility is due to male factors, including the quality of spermatozoa, which is a primary factor and often difficult to assess, particularly the total sperm concentration and its motile percentage. This work presents a simple microfluidic device to assess sperm quality by quantifying both total and motile sperm counts. The key design feature of the microfluidic device is two channels separated by a permeative phase-guide structure, where one channel is filled with raw semen and the other with pure buffer. The semen sample was allowed to reach equilibrium in both chambers, whereas non-motile sperms remained in the original channel, and roughly half of the motile sperms would swim across the phase-guide barrier into the buffer channel. Sperms in each channel agglomerated into pellets after centrifugation, with the corresponding area representing total and motile sperm concentrations. Total sperm concentration up to 10(8) sperms per ml and motile percentage in the range of 10-70% were tested, encompassing the cutoff value of 40% stated by World Health Organization standards. Results from patient samples show compact and robust pellets after centrifugation. Comparison of total sperm concentration between the microfluidic device and the Makler chamber reveal they agree within 5% and show strong correlation, with a coefficient of determination of R(2) = 0.97. Motile sperm count between the microfluidic device and the Makler chamber agrees within 5%, with a coefficient of determination of R(2) = 0.84. Comparison of results from the Makler Chamber, sperm quality analyzer, and the microfluidic device revealed that results from the microfluidic device agree well with the Makler chamber. The sperm microfluidic chip analyzes both total and motile sperm concentrations in one spin, is accurate and easy to use, and should enable sperm quality analysis with ease.

Integration of microelectronic chips in microfluidic systems on printed circuit board

International Nuclear Information System (INIS)

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

2012-01-01

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. (paper)

Chemistry in Microfluidic Channels

Science.gov (United States)

Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

2011-01-01

General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

Magnetic particle mixing with magnetic micro-convection for microfluidics

International Nuclear Information System (INIS)

Kitenbergs, Guntars; Erglis, Kaspars; Perzynski, Régine; Cēbers, Andrejs

2015-01-01

In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele–Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted. - Highlights: • We study the magnetic micro-convection as a mixing method in microfluidics. • We show that the method enhances mixing with magnetic field squared dependency. • We propose a flow cell setup for mixing and justify it with a sample experiment. • The mixing method can be easily implemented in an existing microfluidics setup

Silanization of boron nitride nanosheets (BNNSs) through microfluidization and their use for producing thermally conductive and electrically insulating polymer nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Seyhan, A.Tuğrul, E-mail: atseyhan@anadolu.edu.tr [Department of Materials Science and Engineering, Anadolu University - AU, Iki Eylul Campus, 26550 Eskisehir (Turkey); Composite Materials Manufacturing Science Laboratory (CMMSL), Research and Application Center of Civil Aviation (RACCA), Anadolu University - AU, Iki Eylul Campus, 26550 Eskisehir (Turkey); Göncü, Yapıncak; Durukan, Oya; Akay, Atakan; Ay, Nuran [Department of Materials Science and Engineering, Anadolu University - AU, Iki Eylul Campus, 26550 Eskisehir (Turkey)

2017-05-15

Chemical exfoliation of boron nitride nanosheets (BNNSs) from large flakes of specially synthesized micro-sized hexagonal boron nitride (h-BN) ceramics was carried out through microfluidization. The surface of BNNSs obtained was then functionalized with vinyl-trimethoxy silane (VTS) coupling agent through microfluidization once again in an effort to make them compatible with organic materials, especially those including polymers. The morphology of BNNSs with and without silane treatment was then systematically characterized by conducting various different analytical techniques, including Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Bright field Transmission Electron Microscopy (BF-TEM), Contact angle analyzer (CAA), Particle size analyzer (PSA) and Fourier Transmission Infrared (FTIR) spectroscopy attached with attenuated total reflectance (ATR) module. As a result, the silane treatment was determined to be properly and successfully carried out and to give rise to the irregularity of large flakes of the BNNSs by folding back their free edges upon themselves, which in turn assists in inducing further exfoliation of the few-layered nanosheets. To gain more insight into the effectiveness of the surface functionalization, thermal conductivity of polypropylene (PP) nanocomposites containing different amounts (1 wt% and 5 wt%) of BNNSs with and without silane treatment was experimentally investigated. Regardless of the weight content, PP nanocomposites containing silanized BNNSs were found to exhibit high thermal conductivity compared to PP nanocomposites containing BNNSs without silane treatment. It was concluded that microfluidization possesses the robustness to provide a reliable product quality, whether in small or large quantities, in a very time effective manner, when it comes to first exfoliating two-dimensional inorganic materials into few layered sheets, and functionalizing the surface of these sheets afterwards

Interconnection blocks: a method for providing reusable, rapid, multiple, aligned and planar microfluidic interconnections

International Nuclear Information System (INIS)

Sabourin, D; Snakenborg, D; Dufva, M

2009-01-01

In this paper a method is presented for creating 'interconnection blocks' that are re-usable and provide multiple, aligned and planar microfluidic interconnections. Interconnection blocks made from polydimethylsiloxane allow rapid testing of microfluidic chips and unobstructed microfluidic observation. The interconnection block method is scalable, flexible and supports high interconnection density. The average pressure limit of the interconnection block was near 5.5 bar and all individual results were well above the 2 bar threshold considered applicable to most microfluidic applications

Fabrication of a multiplexed microfluidic system for scaled up production of cross-linked biocatalytic microspheres

CSIR Research Space (South Africa)

Mbanjwa, M

2014-06-01

Full Text Available the design and fabrication of a multiplexed microfluidic system for producing biocatalytic microspheres. The microfluidic system consists of an array of 10 parallel microfluidic circuits, for simultaneous operation to demonstrate increased production...

Cyclohexanone microfluidic extraction of radioactive perrhenate from acid solutions

Energy Technology Data Exchange (ETDEWEB)

Dalmázio, Ilza [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oehlke, Elisabeth, E-mail: E.Oehlke@tudelft.nl [Section Radiation and Isotopes for Health, Department of Radiation Science and Technology, Delft University of Technology (Netherlands)

2017-07-01

Several studies have investigated the application of microfluidic devices in extraction processes. A potential use of microfluidic devices is in radionuclide generators based on solvent extraction, as the {sup 188}W/{sup 188}Re generator. The aim of this work is to present the initial results of microfluidic solvent extraction of radioactive perrhenate. Aqueous solutions of ammonium perrhenate at 0.1 mg/mL (in water, HCl or sodium tungstate) were used as feed solution and cyclohexanone as extractant. As a first step, the fluid behaviour inside the glass microchannel was evaluated to reach laminar flow. The second step was the determination of extraction efficiency using thermal neutron activated perrhenate to produce feed solutions. The extraction conditions permitted liquid-liquid contact times as short as 0.5 s. Increasing of the contact time, resulted in a higher extraction efficiency of perrhenate, e.g. 14 % for 0.5 s and 32 % for 1.1 s using a 0.1 mol/L HCl feed solution. The extraction of perrhenate improved also when applying a feed solution with higher acidity, e.g. 52% for 1 mol/L HCl with contact time of 1.1 s. The influence of adding sodium tungstate to the feed solution was also examined. To the best of our knowledge, these are the first results related to perrhenate solvent extraction using a microfluidic device. The usefulness of microfluidic devices to screen extraction conditions was demonstrated making it possible to evaluate the effect of electrolytes on the perrhenate extraction process in a short time-frame. (author)

A microfluidic approach for hemoglobin detection in whole blood

Directory of Open Access Journals (Sweden)

Nikita Taparia

2017-10-01

Full Text Available Diagnosis of anemia relies on the detection of hemoglobin levels in a blood sample. Conventional blood analyzers are not readily available in most low-resource regions where anemia is prevalent, so detection methods that are low-cost and point-of-care are needed. Here, we present a microfluidic approach to measure hemoglobin concentration in a sample of whole blood. Unlike conventional approaches, our microfluidic approach does not require hemolysis. We detect the level of hemoglobin in a blood sample optically by illuminating the blood in a microfluidic channel at a peak wavelength of 540 nm and measuring its absorbance using a CMOS sensor coupled with a lens to magnify the image onto the detector. We compare measurements in microchannels with channel heights of 50 and 115 μm and found the channel with the 50 μm height provided a better range of detection. Since we use whole blood and not lysed blood, we fit our data to an absorption model that includes optical scattering in order to obtain a calibration curve for our system. Based on this calibration curve and data collected, we can measure hemoglobin concentration within 1 g/dL for severe cases of anemia. In addition, we measured optical density for blood flowing at a shear rate of 500 s-1 and observed it did not affect the nonlinear model. With this method, we provide an approach that uses microfluidic detection of hemoglobin levels that can be integrated with other microfluidic approaches for blood analysis.

Cyclohexanone microfluidic extraction of radioactive perrhenate from acid solutions

International Nuclear Information System (INIS)

Dalmázio, Ilza; Oehlke, Elisabeth

2017-01-01

Several studies have investigated the application of microfluidic devices in extraction processes. A potential use of microfluidic devices is in radionuclide generators based on solvent extraction, as the 188 W/ 188 Re generator. The aim of this work is to present the initial results of microfluidic solvent extraction of radioactive perrhenate. Aqueous solutions of ammonium perrhenate at 0.1 mg/mL (in water, HCl or sodium tungstate) were used as feed solution and cyclohexanone as extractant. As a first step, the fluid behaviour inside the glass microchannel was evaluated to reach laminar flow. The second step was the determination of extraction efficiency using thermal neutron activated perrhenate to produce feed solutions. The extraction conditions permitted liquid-liquid contact times as short as 0.5 s. Increasing of the contact time, resulted in a higher extraction efficiency of perrhenate, e.g. 14 % for 0.5 s and 32 % for 1.1 s using a 0.1 mol/L HCl feed solution. The extraction of perrhenate improved also when applying a feed solution with higher acidity, e.g. 52% for 1 mol/L HCl with contact time of 1.1 s. The influence of adding sodium tungstate to the feed solution was also examined. To the best of our knowledge, these are the first results related to perrhenate solvent extraction using a microfluidic device. The usefulness of microfluidic devices to screen extraction conditions was demonstrated making it possible to evaluate the effect of electrolytes on the perrhenate extraction process in a short time-frame. (author)

A microfluidic approach for hemoglobin detection in whole blood

Science.gov (United States)

Taparia, Nikita; Platten, Kimsey C.; Anderson, Kristin B.; Sniadecki, Nathan J.

2017-10-01

Diagnosis of anemia relies on the detection of hemoglobin levels in a blood sample. Conventional blood analyzers are not readily available in most low-resource regions where anemia is prevalent, so detection methods that are low-cost and point-of-care are needed. Here, we present a microfluidic approach to measure hemoglobin concentration in a sample of whole blood. Unlike conventional approaches, our microfluidic approach does not require hemolysis. We detect the level of hemoglobin in a blood sample optically by illuminating the blood in a microfluidic channel at a peak wavelength of 540 nm and measuring its absorbance using a CMOS sensor coupled with a lens to magnify the image onto the detector. We compare measurements in microchannels with channel heights of 50 and 115 μm and found the channel with the 50 μm height provided a better range of detection. Since we use whole blood and not lysed blood, we fit our data to an absorption model that includes optical scattering in order to obtain a calibration curve for our system. Based on this calibration curve and data collected, we can measure hemoglobin concentration within 1 g/dL for severe cases of anemia. In addition, we measured optical density for blood flowing at a shear rate of 500 s-1 and observed it did not affect the nonlinear model. With this method, we provide an approach that uses microfluidic detection of hemoglobin levels that can be integrated with other microfluidic approaches for blood analysis.

Pneumatic oscillator circuits for timing and control of integrated microfluidics.

Science.gov (United States)