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Sample records for polydimethylsiloxane microchips coated

  1. One-step preparation and application of mussel-inspired poly(norepinephrine)-coated polydimethylsiloxane microchip for separation of chiral compounds.

    PubMed

    Chen, Juan; Liang, Ru-Ping; Wu, Lu-Lu; Qiu, Jian-Ding

    2016-07-01

    In this paper, using the self-polymerization of norepinephrine (NE) and its favorable film-forming property, a simple and green preparation approach was developed to modify a PDMS channel for enantioseparation of chiral compounds. After the PDMS microchip was filled with NE solution, poly(norepinephrine) (PNE) film was gradually formed and deposited on the inner wall of microchannel as permanent coating via the oxidation of NE by the oxygen dissolved in the solution. Due to possessing plentiful catechol and amine functional groups, the PNE-coated PDMS microchip exhibited much better wettability, more stable and suppressed EOF, and less nonspecific adsorption. The water contact angle and EOF of PNE-coated PDMS substrate were measured to be 13° and 1.68 × 10(-4) cm(2) V(-1) s(-1) , compared to those of 108° and 2.24 × 10(-4) cm(2) V(-1) s(-1) from the untreated one, respectively. Different kinds of chiral compounds, such as amino acid enantiomer, drug enantiomer, and peptide enantiomer were efficiently separated utilizing a separation length of 37 mm coupled with in-column amperometric detection on the PNE-coated PDMS microchips. This facile mussel-inspired PNE-based microchip system exhibited strong recognition ability, high-performance, admirable reproducibility, and stability, which may have potential use in the complex biological analysis. PMID:26970233

  2. Polyelectrolyte coatings for microchip capillary electrophoresis.

    PubMed

    Liu, Yan; Henry, Charles S

    2006-01-01

    In chip-based electrophoretic analysis of biomolecules, chemical modification of the microchannel is widely employed to reduce or eliminate the analyte-wall interactions and alter electroosmotic flow (EOF) in the microchannel. A stable polyelectrolyte multilayer coating is one common way to regulate or eliminate EOF and prevent analyte adsorption for the rapid, efficient separation of biomolecules within microchannels. A wide variety of polyelectrolytes have been used as coatings. This chapter deals with how to coat microchips with polyelectrolytes and the expected results using polybrene and dextran sulfate as models. The technique presented here is generally applicable to any polyelectrolyte. PMID:16790867

  3. Integrated hybrid polystyrene-polydimethylsiloxane device for monitoring cellular release with microchip electrophoresis and electrochemical detection

    PubMed Central

    Johnson, Alicia S.; Mehl, Benjamin T.; Martin, R. Scott

    2015-01-01

    In this work, a polystyrene (PS)-polydimethylsiloxane (PDMS) hybrid device was developed to enable the integration of cell culture with analysis by microchip electrophoresis and electrochemical detection. It is shown that this approach combines the fundamental advantages of PDMS devices (the ability to integrate pumps and valves) and PS devices (the ability to permanently embed fluidic tubing and electrodes). The embedded fused-silica capillary enables high temporal resolution measurements from off-chip cell culture dishes and the embedded electrodes provide close to real-time analysis of small molecule neurotransmitters. A novel surface treatment for improved (reversible) adhesion between PS and PDMS is described using a chlorotrimethylsilane stamping method. It is demonstrated that a Pd decoupler is efficient at handling the high current (and cathodic hydrogen production) resulting from use of high ionic strength buffers needed for cellular analysis; thus allowing an electrophoretic separation and in-channel detection. The separation of norepinephrine (NE) and dopamine (DA) in highly conductive biological buffers was optimized using a mixed surfactant system. This PS-PDMS hybrid device integrates multiple processes including continuous sampling from a cell culture dish, on-chip pump and valving technologies, microchip electrophoresis, and electrochemical detection to monitor neurotransmitter release from PC 12 cells. PMID:25663849

  4. Ultrasensitive Nanoelectrospray Ionization-Mass Spectrometry using Poly(dimethylsiloxane) Microchips with Monolithically Integrated Emitters

    SciTech Connect

    Sun, Xuefei; Kelly, Ryan T.; Tang, Keqi; Smith, Richard D.

    2010-09-01

    Poly(dimethylsiloxane) (PDMS) is the most widely used substrate for microfluidic devices as it enables facile fabrication and has other distinctive properties. However, for applications involving highly sensitive nanoelectrospray ionization mass spectrometry (nanoESI-MS) detection, the use of PDMS microdevices has been hindered by the leaching of uncross-linked oligomers and other contaminants from the substrate that yields a large background of chemical noise in the mass spectra. A more general challenge is that microfluidic devices containing integrated electrospray emitters are frequently unable to operate stably in the nanoflow regime where the best sensitivity is achieved. In this report, we extracted the contaminants from PDMS substrates using a series of solvents, eliminating the background observed when untreated PDMS microchips are used for nanoESI-MS. Optimization of the integrated emitter geometry enabled stable operation at flow rates as low as 10 nL/min. Peptide concentrations of 1 nM were readily detected, representing ~170 zmol of consumed analyte, and an extrapolated detection limit of ~40 zmol; these are the lowest mass and concentration detection limits reported to date for a microchip having an integrated electrospray emitter.

  5. Poly(dimethylsiloxane) microchip-based immunoassay with multiple reaction zones: Toward on-chip multiplex detection platform

    SciTech Connect

    Shao, Guocheng; Wang, Jun; Li, Zhaohui; Saraf, Laxmikant V.; Wang, Wanjun; Lin, Yuehe

    2011-09-20

    In this work, a poly(dimethylsiloxane) (PDMS) microchip-based immuno-sensing platform with integrated pneumatic micro valves is described. The microchip was fabricated with multiple layer soft lithography technology. By controlling the activation status of corresponding valves, reagent flows in the microchannel network can be well manipulated so that immuno-reactions only take place at designated reaction zones (DRZs). Four DRZs are included in the prototype microchip. Since these DRZs are all isolated from each other by micro valves, cross contamination is prevented. Using the inner surface of the all-PDMS microchannel as immunoassay substrate, on-chip sandwich format solid phase immunoassay was performed to demonstrate the feasibility of this immuno-sensing platform. Mouse IgG and fluorescein isothiocyanate (FITC) were used as the model analyte and the signal reporter respectively. Only 10 ul sample is needed for the assay and low detection limit of 5 ng/ml (≈33 pM) was achieved though low-cost polyclonal antibodies were used in our experiment for feasibility study only. The encouraging results from mouse IgG immunoassay proved the feasibility of our microchip design. With slight modification of the assay protocol, the same chip design can be used for multi-target detection and can provide a simple, cost-effective and integrated microchip solution for multiplex immunoassay applications.

  6. Stable low-fouling plasma polymer coatings on polydimethylsiloxane

    PubMed Central

    Forster, S.; McArthur, S. L.

    2012-01-01

    Polydimethylsiloxane (DMS) is a popular material for microfluidics, but it is hydrophobic and is prone to non-specific protein adsorption. In this study, we explore methods for producing stable, protein resistant, tetraglyme plasma polymer coatings on PDMS by combining extended baking processes with multiple plasma polymer coating steps. We demonstrate that by using this approach, it is possible to produce a plasma polymer coatings that resist protein adsorption (<10 ng/cm2) and are stable to storage over at least 100 days. This methodology can translate to any plasma polymer system, enabling the introduction of a wide range of surface functionalities on PDMS surfaces. PMID:24062864

  7. Polydimethylsiloxane-based self-healing composite and coating materials

    NASA Astrophysics Data System (ADS)

    Cho, Soo Hyoun

    This thesis describes the science and technology of a new class of autonomic polymeric materials which mimic some of the functionalities of biological materials. Specifically, we demonstrate an autonomic self-healing polymer system which can heal damage in both coatings and bulk materials. The new self-healing system we developed greatly extends the capability of self-healing polymers by introducing tin catalyzed polycondensation of hydroxyl end-functionalited polydimethylsiloxane and polydiethoxysiloxane based chemistries. The components in this system are widely available and comparatively low in cost, and the healing chemistry also remains stable in humid or wet environments. These achievements significantly increase the probability that self-healing could be extended not only to polymer composites but also to coatings and thin films in harsh environments. We demonstrate the bulk self-healing property of a polymer composite composed of a phase-separated PDMS healing agent and a microencapsulated organotin catalyst by chemical and mechanical testing. Another significant research focus is on self-healing polymer coatings which prevent corrosion of a metal substrate after deep scratch damage. The anti-corrosion properties of the self-healing polymer on metal substrates are investigated by corrosion resistance and electrochemical tests. Even after scratch damage into the substrate, the coating is able to heal, while control samples which do not include all the necessary healing components reveal rapid corrosion propagation. This self-healing coating solution can be easily applied to most substrate materials, and is compatible with most common polymer matrices. Self-healing has the potential to extend the lifetime and increase the reliability of thermosetting polymers used in a wide variety of applications ranging from microelectronics to aerospace.

  8. Formation of lipid bilayer membrane in a poly(dimethylsiloxane) microchip integrated with a stacked polycarbonate membrane support and an on-site nanoinjector.

    PubMed

    Teng, Wei; Ban, Changill; Hahn, Jong Hoon

    2015-03-01

    This paper describes a new and facile approach for the formation of pore-spanning bilayer lipid membranes (BLMs) within a poly(dimethylsiloxane) (PDMS) microfluidic device. Commercially, readily available polycarbonate (PC) membranes are employed for the support of BLMs. PC sheets with 5 μm, 2 μm, and 0.4 μm pore diameters, respectively, are thermally bonded into a multilayer-stack, reducing the pore density of 0.4 μm-pore PC by a factor of 200. The BLMs on this support are considerably stable (a mean lifetime: 17 h). This multilayer-stack PC (MSPC) membrane is integrated into the PDMS chip by an epoxy bonding method developed to secure durable bonding under the use of organic solvents. The microchip has a special channel for guiding a micropipette in the proximity of the MSPC support. With this on-site injection technique, tens to hundreds of nanoliters of solutions can be directly dispensed to the support. Incorporating gramicidin ion channels into BLMs on the MSPC support has confirmed the formation of single BLMs, which is based on the observation from current signals of 20 pS conductance that is typical to single channel opening. Based on the bilayer capacitance (1.4 pF), about 15% of through pores across the MSPC membrane are estimated to be covered with BLMs. PMID:26015832

  9. Formation of lipid bilayer membrane in a poly(dimethylsiloxane) microchip integrated with a stacked polycarbonate membrane support and an on-site nanoinjector

    PubMed Central

    Teng, Wei; Ban, Changill; Hahn, Jong Hoon

    2015-01-01

    This paper describes a new and facile approach for the formation of pore-spanning bilayer lipid membranes (BLMs) within a poly(dimethylsiloxane) (PDMS) microfluidic device. Commercially, readily available polycarbonate (PC) membranes are employed for the support of BLMs. PC sheets with 5 μm, 2 μm, and 0.4 μm pore diameters, respectively, are thermally bonded into a multilayer-stack, reducing the pore density of 0.4 μm-pore PC by a factor of 200. The BLMs on this support are considerably stable (a mean lifetime: 17 h). This multilayer-stack PC (MSPC) membrane is integrated into the PDMS chip by an epoxy bonding method developed to secure durable bonding under the use of organic solvents. The microchip has a special channel for guiding a micropipette in the proximity of the MSPC support. With this on-site injection technique, tens to hundreds of nanoliters of solutions can be directly dispensed to the support. Incorporating gramicidin ion channels into BLMs on the MSPC support has confirmed the formation of single BLMs, which is based on the observation from current signals of 20 pS conductance that is typical to single channel opening. Based on the bilayer capacitance (1.4 pF), about 15% of through pores across the MSPC membrane are estimated to be covered with BLMs. PMID:26015832

  10. In-channel indirect amperometric detection of heavy metal ions for electrophoresis on a poly(dimethylsiloxane) microchip.

    PubMed

    Li, Xin-Ai; Zhou, Dong-Mei; Xu, Jing-Juan; Chen, Hong-Yuan

    2007-02-28

    In-channel indirect amperometric detection mode for microchip capillary electrophoresis with positive separation electric field is successfully applied to some heavy metal ions. The influences of separation voltage, detection potential, the concentration and pH value of running buffer on the response of the detector have been investigated. An optimized condition of 1200V separation voltage, -0.1V detection potential, 20mM (pH 4.46) running buffer of 2-(N-morpholino)ethanesulfonic acid (MES)+l-histidine (l-His) was selected. The results clearly showed that Pb(2+), Cd(2+), and Cu(2+) were efficiently separated within 80s in a 3.7cm long native separation PDMS/PDMS channel and successfully detected at a single carbon fibre electrode. The theoretical plate numbers of Pb(2+), Cd(2+), and Cu(2+) were 1.2x10(5), 2.5x10(5), and 1.9x10(5)m(-1), respectively. The detection limits for Pb(2+), Cd(2+), and Cu(2+) were 1.3, 3.3 and 7.4muM (S/N=3). PMID:19071423

  11. Surface studies on superhydrophobic and oleophobic polydimethylsiloxane-silica nanocomposite coating system

    NASA Astrophysics Data System (ADS)

    Basu, Bharathibai J.; Dinesh Kumar, V.; Anandan, C.

    2012-11-01

    Superhydrophobic and oleophobic polydimethylsiloxane (PDMS)-silica nanocomposite double layer coating was fabricated by applying a thin layer of low surface energy fluoroalkyl silane (FAS) as topcoat. The coatings exhibited WCA of 158-160° and stable oleophobic property with oil CA of 79°. The surface morphology was characterized by field emission scanning electron microscopy (FESEM) and surface chemical composition was determined by energy dispersive X-ray spectrometery (EDX) and X-ray photoelectron spectroscopy (XPS). FESEM images of the coatings showed micro-nano binary structure. The improved oleophobicity was attributed to the combined effect of low surface energy of FAS and roughness created by the random distribution of silica aggregates. This is a facile, cost-effective method to obtain superhydrophobic and oleophobic surfaces on larger area of various substrates.

  12. High-speed separation of proteins by microchip electrophoresis using a polyethylene glycol-coated plastic chip with a sodium dodecyl sulfate-linear polyacrylamide solution.

    PubMed

    Nagata, Hideya; Tabuchi, Mari; Hirano, Ken; Baba, Yoshinobu

    2005-07-01

    In this paper, we describe a method for size-based electrophoretic separation of sodium dodecyl sulfate (SDS)-protein complexes on a polymethyl methacrylate (PMMA) microchip, using a separation buffer solution containing SDS and linear polyacrylamide as a sieving matrix. We developed optimum conditions under which protein separations can be performed, using polyethylene glycol (PEG)-coated polymer microchips and electrokinetic sample injection. We studied the performance of protein separations on the PEG-coated PMMA microchip. The electrophoretic separation of proteins (21.5-116.0 kDa) was completed with separation lengths of 3 mm, achieved within 8 s on the PEG-coated microchip. This high-speed method may be applied to protein separations over a large range of molecular weight, making the PEG-coated microchip approach applicable to high-speed proteome analysis systems. PMID:15937980

  13. Accurate measurement of the sticking time and sticking probability of Rb atoms on a polydimethylsiloxane coating

    SciTech Connect

    Atutov, S. N. Plekhanov, A. I.

    2015-01-15

    We present the results of a systematic study of Knudsen’s flow of Rb atoms in cylindrical capillary cells coated with a polydimethylsiloxane (PDMS) compound. The purpose of the investigation is to determine the characterization of the coating in terms of the sticking probability and sticking time of Rb on the two types of coating of high and medium viscosities. We report the measurement of the sticking probability of a Rb atom to the coating equal to 4.3 × 10{sup −5}, which corresponds to the number of bounces 2.3 × 10{sup 4} at room temperature. These parameters are the same for the two kinds of PDMS used. We find that at room temperature, the respective sticking times for high-viscosity and medium-viscosity PDMS are 22 ± 3 μs and 49 ± 6 μs. These sticking times are about million times larger than the sticking time derived from the surface Rb atom adsorption energy and temperature of the coating. A tentative explanation of this surprising result is proposed based on the bulk diffusion of the atoms that collide with the surface and penetrate inside the coating. The results can be important in many resonance cell experiments, such as the efficient magnetooptical trapping of rare elements or radioactive isotopes and in experiments on the light-induced drift effect.

  14. Polydimethylsiloxane Coating for a Palladium/MOF Composite: Highly Improved Catalytic Performance by Surface Hydrophobization.

    PubMed

    Huang, Gang; Yang, Qihao; Xu, Qiang; Yu, Shu-Hong; Jiang, Hai-Long

    2016-06-20

    Surface wettability of active sites plays a crucial role in the activity and selectivity of catalysts. This report describes modification of surface hydrophobicity of Pd/UiO-66, a composite comprising a metal-organic framework (MOF) and stabilized palladium nanoparticles (NPs), using a simple polydimethylsiloxane (PDMS) coating. The modified catalyst demonstrated significantly improved catalytic efficiency. The approach can be extended to various Pd nanoparticulate catalysts for enhanced activity in reactions involving hydrophobic reactants, as the hydrophobic surface facilitates the enrichment of hydrophobic substrates around the catalytic site. PDMS encapsulation of Pd NPs prevents aggregation of NPs and thus results in superior catalytic recyclability. Additionally, PDMS coating is applicable to a diverse range of catalysts, endowing them with additional selectivity in sieving reactants with different wettability. PMID:27144320

  15. Uniform polydimethylsiloxane beads coated with polydopamine and their potential biomedical applications.

    PubMed

    Jun, Dae-Ryong; Moon, Seung-Kwan; Choi, Sung-Wook

    2014-09-01

    Based on oil-in-water emulsion, uniform poly(dimethylsiloxane) (PDMS) beads were prepared using a simple fluidic device and then modified with polydopamine (PDA) to improve cell attachment. The size of the PDMS beads could be easily tuned by changing the flow rates of the discontinuous and continuous phases, and PDMS concentration in oil phase. The PDA-coated PDMS beads exhibited a dark and rough surface, whereas the pristine PDMS beads had a clear and smooth surface. The PDA layer at the surface of the PDMS beads was found to provide a favorable environment for cell culture due to its hydrophilic property. The PDA-coated PDMS beads can potentially be employed as filler materials for tissue engineering. PMID:24993068

  16. Internal modification of poly(dimethylsiloxane) microchannels with a borosilicate glass coating.

    PubMed

    Orhan, J-B; Parashar, V K; Flueckiger, J; Gijs, M A M

    2008-08-19

    We report on an original technique for the in situ coating of poly(dimethylsiloxane) (PDMS) microchannels with borosilicate glass, starting from an active nonaqueous and alkali-free precursor solution. By chemical reaction of this active solution inside the microchannel and subsequent thermal annealing, a protective and chemically inert glass borosilicate coating is bonded to the PDMS. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and nuclear magnetic resonance spectroscopy of the active solution show that it is composed of a silicon oxide network with boron connectivity. Thermal gravimetric analysis demonstrates the absence of organic content when curing is done above 150 degrees C. The borosilicate nature of the glass coating covalently bonded to the PDMS is demonstrated using ATR-FTIR spectroscopy and X-ray photoelectron spectroscopy. Atomic force microscopy and scanning electron microscopy show a smooth and crack-free coating. The latter is used as an efficient protective barrier against diffusion in PDMS of fluorescent rhodamine B dye that is dissolved either in water or in toluene. Moreover, the coating prevents swelling and consequent structural damage of the PDMS when the latter is exposed to harsh chemicals such as toluene. PMID:18652427

  17. A general microchip surface modification approach using a spin-coated polymer resist film doped with hydroxypropyl cellulose.

    PubMed

    Sun, Xiuhua; Yang, Weichun; Geng, Yanli; Woolley, Adam T

    2009-04-01

    We have developed a simple and effective method for surface modification of polymer microchips by entrapping hydroxypropyl cellulose (HPC) in a spin-coated thin film on the surface. Poly(methyl methacrylate-8.5-methacrylic acid), a widely available commercial resist formulation, was utilized as a matrix for dissolving HPC and providing adherence to native polymer surfaces. Various amounts of HPC (0.1-2.0%) dissolved in the copolymer and spun on polymer surfaces were evaluated. The modified surfaces were characterized by contact angle measurement, X-ray photoelectron spectroscopy and atomic force microscopy. The developed method was applied on both poly(methyl methacrylate) and cyclic olefin copolymer microchips. A fluorescently labeled myoglobin digest, binary protein mixture, and human serum sample were all separated in these surface-modified polymer microdevices. Our work exhibits an easy and reliable way to achieve favorable biomolecular separation performance in polymer microchips. PMID:19294306

  18. Niobium oxide-polydimethylsiloxane hybrid composite coatings for tuning primary fibroblast functions.

    PubMed

    Young, Matthew D; Tran, Nhiem; Tran, Phong A; Jarrell, John D; Hayda, Roman A; Born, Chistopher T

    2014-05-01

    This study evaluates the potential of niobium oxide-polydimethylsiloxane (PDMS) composites for tuning cellular response of fibroblasts, a key cell type of soft tissue/implant interfaces. In this study, various hybrid coatings of niobium oxide and PDMS with different niobium oxide concentrations were synthesized and characterized using scanning electron microscopy, X-ray photoelectron spectrometry (XPS), and contact angle goniometry. The coatings were then applied to 96-well plates, on which primary fibroblasts were seeded. Fibroblast viability, proliferation, and morphology were assessed after 1, 2, and 3 days of incubation using WST-1 and calcein AM assays along with fluorescent microscopy. The results showed that the prepared coatings had distinct surface features with submicron spherical composites covered in a polymeric layer. The water contact angle measurement demonstrated that the hybrid surfaces were much more hydrophobic than the original pure niobium oxide and PDMS. The combination of surface roughness and chemistry resulted in a biphasic cellular response with maximum fibroblast density on substrate with 40 wt % of niobium oxide. The results of the current study indicate that by adjusting the concentration of niobium oxide in the coating, a desirable cell response can be achieved to improve tissue/implant interfaces. PMID:23776075

  19. Non-silicon substrate bonding mediated by poly(dimethylsiloxane) interfacial coating

    NASA Astrophysics Data System (ADS)

    Zhang, Hainan; Lee, Nae Yoon

    2015-02-01

    In this paper, we introduce a simple and robust strategy for bonding poly(dimethylsiloxane) (PDMS) with various thermoplastic substrates to fabricate a thermoplastic-based closed microfluidic device and examine the feasibility of using the proposed method for realizing plastic-plastic bonding. The proposed bonding strategy was realized by first coating amine functionality on an oxidized thermoplastic surface. Next, the amine-functionalized surface was reacted with a monolayer of low-molecular-weight PDMS, terminated with epoxy functionality, by forming a robust amine-epoxy bond. Both the PDMS-coated thermoplastic and PDMS were then oxidized and permanently assembled at 25 °C under a pressure of 0.1 MPa for 15 min, resulting in PDMS-like surfaces on all four inner walls of the microchannel. Surface characterizations were conducted, including water contact angle measurement, X-ray photoelectron spectroscopy (XPS), and fluorescence measurement, to confirm the successful coating of the thin PDMS layer on the plastic surface, and the bond strength was analyzed by conducting a peel test, burst test, and leakage test. Using the proposed method, we could successfully bond various thermoplastics such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polystyrene (PS), and poly(ethylene terephthalate) (PET) with PDMS without the collapse or deformation of the microchannel, and the proposed method was successfully extended to the bonding of two thermoplastics, PMMA, and PC.

  20. High-Efficiency Capture of Individual and Cluster of Circulating Tumor Cells by a Microchip Embedded with Three-Dimensional Poly(dimethylsiloxane) Scaffold.

    PubMed

    Cheng, Shi-Bo; Xie, Min; Xu, Jia-Quan; Wang, Jing; Lv, Song-Wei; Guo, Shan; Shu, Ying; Wang, Ming; Dong, Wei-Guo; Huang, Wei-Hua

    2016-07-01

    Effective isolation of circulating tumor cells (CTCs) has great significance for cancer research but is highly challenged. Here, we developed a microchip embedded with a three-dimensional (3D) PDMS scaffold by a quadratic-sacrificing template method for high-efficiency capture of CTCs. The microchip was gifted with a 3D interconnected macroporous structure, strong toughness, and excellent flexibility and transparency, enabling fast isolation and convenient observation of CTCs. Especially, 3D scaffold chip perfectly integrates the two main strategies currently used for enhancement of cell capture efficiency. Spatially distributed 3D scaffold compels cells undergoing chaotic or vortex migration in the channel, and the spatially distributed nanorough skeleton offers ample binding sites, which synergistically and significantly improve CTCs capture efficiency. Our results showed that 1-118 CTCs/mL were identified from 14 cancer patients' blood and 5 out of these cancer patients showed 1-14 CTC clusters/mL. This work demonstrates for the first time the development of microchip with transparent interconnected 3D scaffold for isolation of CTCs and CTC clusters, which may promote in-depth analysis of CTCs. PMID:27291464

  1. Disposable Polydimethylsiloxane (PDMS)-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths

    PubMed Central

    Lievers, Rik; Groot, Astrid T.

    2016-01-01

    In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small) groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS) by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses. PMID:27533064

  2. Disposable Polydimethylsiloxane (PDMS)-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths.

    PubMed

    Lievers, Rik; Groot, Astrid T

    2016-01-01

    In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small) groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS) by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses. PMID:27533064

  3. Superhydro-oleophobic bio-inspired polydimethylsiloxane micropillared surface via FDTS coating/blending approaches

    NASA Astrophysics Data System (ADS)

    Pan, Zihe; Shahsavan, Hamed; Zhang, Wei; Yang, Fut K.; Zhao, Boxin

    2015-01-01

    In this work we render superhydro-oleophobic properties to the surface of polydimethylsiloxane (PDMS) elastomer through bio-inspired micropillar surface and chemical modification with a fluorosilane polymer, trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS). Two different chemical modification approaches were applied on both flat and micropillar PDMS: (1) vapor deposition of FDTS on cured PDMS surface, and (2) blending FDTS with the liquid PDMS precursor before curing. Comparative studies of the water and oil contact angles on the neat and FDTS-modified PDMS (both flat and micropillar) indicated that superhydro-oleophobicity was delivered by a combination of FDTS chemistry and micropillar geometry. FDTS-blended PDMS micropillar displayed better oleophobicity with an oil contact angle of ∼141° than FDTS-coated PDMS micropillar (∼115°). In contrast to the smooth surface of FDTS-blended PDMS micropillar, rough surface with some structure defects were found on the FDTS-coated micropillar surface caused by the vapor deposition process; the surface defects might be responsible for the observed low oleophobicity of FDTS-coated PDMS micropillar. Superhydrophobicity of FDTS-blended PDMS micropillar in terms of water contact angles was found to be independent of the quantity of FDTS. However, the oleophobicity of FDTS-blended PDMS micropillar was found to be dependent of the quantity of FDTS; with the increased weight concentration of FDTS in PDMS, the oils contact angle first increased and then leveled out at a finite concentration. FTIR and XPS were applied to analyze surface chemistry information suggesting the blended FDTS segregated from bulk PDMS and enriched at the surface to reduce surface tension so as to make surface super-oleophobic.

  4. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    NASA Astrophysics Data System (ADS)

    Qin, Xiaoshuai; Li, Yancai; Zhou, Fang; Ren, Lixia; Zhao, Yunhui; Yuan, Xiaoyan

    2015-02-01

    Block copolymers PDMS-b-PDMAEMA were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization involving N,N-dimethylaminoethyl methacrylate (DMAEMA) by using poly(dimethylsiloxane) (PDMS) macro-chain transfer agent. And, the tertiary amino groups in PDMAEMA were quaternized with n-octyliodide to provide quaternary ammonium salts (QPDMAEMA). The well-defined copolymers generated composition variation and morphology evolvement on film surfaces, which were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The results indicated that the enrichment of QPDMAEMA brought about lower elemental ratios of Si/N on the film surfaces. The surface morphologies evolved with the variations of QPDMAEMA content, and the variation trend of film roughness was exactly opposite to that of water contact angle hysteresis. With regard to structure-antimicrobial relationships, the copolymer films had more evident antimicrobial activity against Gram-positive, Bacillus subtilis, and the surfaces with heterogeneous morphology and higher N+ content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings.

  5. Hydrophobic polydimethylsiloxane (PDMS) coating of mesoporous silica and its use as a preconcentrating agent of gas analytes.

    PubMed

    Park, Eun Ji; Cho, Youn Kyoung; Kim, Dae Han; Jeong, Myung-Geun; Kim, Yong Ho; Kim, Young Dok

    2014-09-01

    Mesoporous silica with mean pore size of ∼14 nm was coated by polydimethylsiloxane (PDMS) using a thermal deposition method. We showed that the inner walls of pores larger than ∼8 nm can be coated by thin layers of PDMS, and the surfaces consisting of PDMS-coated silica were superhydrophobic, with water contact angles close to 170°. We used the PDMS-coated silica as adsorbents of various gas-phase chemical warfare agent (CWA) simulants. PDMS-coated silica allowed molecular desorption of various CWA simulants even after exposure under highly humid conditions and, therefore, is applicable as an agent for the preconcentration of gas-phase analytes to enhance the sensitivities of various sensors. PMID:25102134

  6. Poly(dimethylsiloxane) thin films as biocompatible coatings for microfluidic devices : cell culture and flow studies with glial cells.

    SciTech Connect

    Peterson, Sophie Louise; Sasaki, Darryl Yoshio; Gourley, Paul Lee; McDonald, Anthony Eugene

    2004-06-01

    Oxygen plasma treatment of poly(dimethylsiloxane) (PDMS) thin films produced a hydrophilic surface that was biocompatible and resistant to biofouling in microfluidic studies. Thin film coatings of PDMS were previously developed to provide protection for semiconductor-based microoptical devices from rapid degradation by biofluids. However, the hydrophobic surface of native PDMS induced rapid clogging of microfluidic channels with glial cells. To evaluate the various issues of surface hydrophobicity and chemistry on material biocompatibility, we tested both native and oxidized PDMS (ox-PDMS) coatings as well as bare silicon and hydrophobic alkane and hydrophilic oligoethylene glycol silane monolayer coated under both cell culture and microfluidic studies. For the culture studies, the observed trend was that the hydrophilic surfaces supported cell adhesion and growth, whereas the hydrophobic ones were inhibitive. However, for the fluidic studies, a glass-silicon microfluidic device coated with the hydrophilic ox-PDMS had an unperturbed flow rate over 14 min of operation, whereas the uncoated device suffered a loss in rate of 12%, and the native PDMS coating showed a loss of nearly 40%. Possible protein modification of the surfaces from the culture medium also were examined with adsorbed films of albumin, collagen, and fibrinogen to evaluate their effect on cell adhesion.

  7. Low-temperature solid-state microwave reduction of graphene oxide for transparent electrically conductive coatings on flexible polydimethylsiloxane (PDMS).

    PubMed

    Liang, Qizhen; Hsie, Sinsar Alec; Wong, Ching Ping

    2012-11-12

    Microwaves (MWs) are applied to initialize deoxygenation of graphene oxide (GO) in the solid state and at low temperatures (∼165 °C). The Fourier-transform infrared (FTIR) spectra of MW-reduced graphene oxide (rGO) show a significantly reduced concentration of oxygen-containing functional groups, such as carboxyl, hydroxyl and carbonyl. X-ray photoelectron spectra confirm that microwaves can promote deoxygenation of GO at relatively low temperatures. Raman spectra and TGA measurements indicate that the defect level of GO significantly decreases during the isothermal solid-state MW-reduction process at low temperatures, corresponding to an efficient recovery of the fine graphene lattice structure. Based on both deoxygenation and defect-level reduction, the resurgence of interconnected graphene-like domains contributes to a low sheet resistance (∼7.9×10(4) Ω per square) of the MW-reduced GO on SiO(2) -coated Si substrates with an optical transparency of 92.7 % at ∼547 nm after MW reduction, indicating the ultrahigh efficiency of MW in GO reduction. Moreover, the low-temperature solid-state MW reduction is also applied in preparing flexible transparent conductive coatings on polydimethylsiloxane (PDMS) substrates. UV/Vis measurements indicate that the transparency of the thus-prepared MW-reduced GO coatings on PDMS substrates ranges from 34 to 96 %. Correspondingly, the sheet resistance of the coating ranges from 10(5) to 10(9) Ω per square, indicating that MW reduction of GO is promising for the convenient low-temperature preparation of transparent conductors on flexible polymeric substrates. PMID:22930478

  8. Ultraviolet sealing and poly(dimethylacrylamide) modification for poly(dimethylsiloxane)/glass microchips.

    PubMed

    Chen, Lin; Ren, Jicun; Bi, Rui; Chen, Di

    2004-03-01

    Simple sealing methods for poly(dimethylsiloxane) (PDMS)/glass-based capillary electrophoresis (CE) microchips by UV irradiation are described. Further, we examined the possibility to modify the inner surface of separation channels, using polymethylacrylamide (PDMA) as a dynamic coating reagent. The surface properties of native PDMS, UV-irradiated PDMS, and PDMA-coated PDMS were systematically studied by atomic force microscopy (AFM), infrared absorption by attenuated total reflection infrared (ATR-IR) spectroscopy, and contact angle measurement. We found that PDMA forms a stable coating on PDMS and glass surfaces, eliminating the nonhomogeneous electroosmotic flow (EOF) in channels on PDMS/glass microchips, and improving the hydrophilicity of PDMS surfaces. Mixtures of flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and fluorescein were separated in 35 s using PDMA-coated PDMS/glass microchips. A high efficiency of theoretical plates with at least 1365 (105 000 N/m) and a good reproducibility with relative standard deviations (RSD) below 4% in five successive separations were achieved. PMID:15004855

  9. Stretchable Array of Highly Sensitive Pressure Sensors Consisting of Polyaniline Nanofibers and Au-Coated Polydimethylsiloxane Micropillars.

    PubMed

    Park, Heun; Jeong, Yu Ra; Yun, Junyeong; Hong, Soo Yeong; Jin, Sangwoo; Lee, Seung-Jung; Zi, Goangseup; Ha, Jeong Sook

    2015-10-27

    We report on the facile fabrication of a stretchable array of highly sensitive pressure sensors. The proposed pressure sensor consists of the top layer of Au-deposited polydimethylsiloxane (PDMS) micropillars and the bottom layer of conductive polyaniline nanofibers on a polyethylene terephthalate substrate. The sensors are operated by the changes in contact resistance between Au-coated micropillars and polyaniline according to the varying pressure. The fabricated pressure sensor exhibits a sensitivity of 2.0 kPa(-1) in the pressure range below 0.22 kPa, a low detection limit of 15 Pa, a fast response time of 50 ms, and high stability over 10000 cycles of pressure loading/unloading with a low operating voltage of 1.0 V. The sensor is also capable of noninvasively detecting human-pulse waveforms from carotid and radial artery. A 5 × 5 array of the pressure sensors on the deformable substrate, which consists of PDMS islands for sensors and the mixed thin film of PDMS and Ecoflex with embedded liquid metal interconnections, shows stable sensing of pressure under biaxial stretching by 15%. The strain distribution obtained by the finite element method confirms that the maximum strain applied to the pressure sensor in the strain-suppressed region is less than 0.04% under a 15% biaxial strain of the unit module. This work demonstrates the potential application of our proposed stretchable pressure sensor array for wearable and artificial electronic skin devices. PMID:26381467

  10. Detection of polydimethylsiloxanes transferred from silicone-coated parchment paper to baked goods using direct analysis in real time mass spectrometry.

    PubMed

    Jakob, Andreas; Crawford, Elizabeth A; Gross, Jürgen H

    2016-04-01

    The non-stick properties of parchment papers are achieved by polydimethylsiloxane (PDMS) coatings. During baking, PDMS can thus be extracted from the silicone-coated parchment into the baked goods. Positive-ion direct analysis in real time (DART) mass spectrometry (MS) is highly efficient for the analysis of PDMS. A DART-SVP source was coupled to a quadrupole-time-of-flight mass spectrometer to detect PDMS on the contact surface of baked goods after use of silicone-coated parchment papers. DART spectra from the bottom surface of baked cookies and pizzas exhibited signals because of PDMS ions of the general formula [(C2H6SiO)n  + NH4 ](+) in the m/z 800-1900 range. PMID:27041660

  11. Superhydrophobic and superoleophilic polydimethylsiloxane-coated cotton for oil-water separation process: An evidence of the relationship between its loading capacity and oil absorption ability.

    PubMed

    Jin, Yangxin; Jiang, Peng; Ke, Qingping; Cheng, Feihuan; Zhu, Yinshengnan; Zhang, Yixiang

    2015-12-30

    Developing functional porous materials with highly efficient oil-water separation ability are of great importance due to the global scale of severe water pollution arising from oil spillage and chemical leakage. A solution immersion process was used to fabricate polydimethylsiloxane (PDMS)-coated cotton, which exhibited superhydrophobic and superoleophilic properties. The water contact angle of ∼ 157° and mass of ∼ 1.49 g were retained after 1000 compression cycles, indicating that the PDMS was strongly attached to the cotton fibres. The PDMS-coated cotton absorbed various oils and organic solvents with high selectivity, high absorption capacity (up to 7080 wt.%), and good recyclability (exceeding 500 cycles). Notably, the loading capacity of the PDMS-coated cotton against water exhibited a similar trend to its oil absorption capacity. These findings will further the application of superhydrophobic and superoleophilic porous materials in oil/water separation. PMID:26184799

  12. Science and Technology of Bio-Inert Thin Films as Hermetic-Encapsulating Coatings for Implantable Biomedical Devices: Application to Implantable Microchip in the Eye for the Artificial Retina

    NASA Astrophysics Data System (ADS)

    Auciello, Orlando; Shi, Bing

    Extensive research has been devoted to the development of neuron prostheses and hybrid bionic systems to establish links between the nervous system and electronic or robotic prostheses with the main focus of restoring motor and sensory functions in blind patients. Artificial retinas, one type of neural prostheses we are currently working on, aim to restore some vision in blind patients caused by retinitis picmentosa or macular degeneration, and in the future to restore vision at the level of face recognition, if not more. Currently there is no hermetic microchip-size coating that provides a reliable, long-term (years) performance as encapsulating coating for the artificial retina Si microchip to be implanted inside the eye. This chapter focuses on the critical topics relevant to the development of a robust, long-term artificial retina device, namely the science and technology of hermetic bio-inert encapsulating coatings to protect a Si microchip implanted in the human eye from being attacked by chemicals existing in the eye's saline environment. The work discussed in this chapter is related to the development of a novel ultrananocrystalline diamond (UNCD) hermetic coating, which exhibited no degradation in rabbit eyes. The material synthesis, characterization, and electrochemical properties of these hermetic coatings are reviewed for application as encapsulating coating for the artificial retinal microchips implantable inside the human eye. Our work has shown that UNCD coatings may provide a reliable hermetic bio-inert coating technology for encapsulation of Si microchips implantable in the eye specifically and in the human body in general. Electrochemical tests of the UNCD films grown under CH4/Ar/H2 (1%) plasma exhibit the lowest leakage currents (˜7 × 10-7 A/cm2) in a saline solution simulating the eye environment. This leakage is incompatible with the functionality of the first-generation artificial retinal microchip. However, the growth of UNCD on top of the

  13. Polydimethylsiloxane/metal-organic frameworks coated fiber for solid-phase microextraction of polycyclic aromatic hydrocarbons in river and lake water samples.

    PubMed

    Zhang, Guijiang; Zang, Xiaohuan; Li, Zhi; Wang, Chun; Wang, Zhi

    2014-11-01

    In this study, polydimethylsiloxane/metal-organic frameworks (PDMS/MOFs), including PDMS/MIL-101 and PDMS/MOF-199, were immobilized onto a stainless steel wire through sol-gel technique as solid-phase microextraction (SPME) fiber coating. The prepared fibers were used for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatography-mass spectrometry (GC-MS) analysis. Under the optimized experiment conditions, the PDMS/MIL-101 coated fiber exhibited higher extraction efficiency towards PAHs than that of PDMS/MOF-199. Several parameters affecting the extraction of PAHs by SPME with PDMS/MIL-101 fiber, including the extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. The limits of detection (LODs) were less than 4.0 ng L(-1) and the linearity was observed in the range from 0.01 to 2.0 µg L(-1) with the correlation coefficients (r) ranging from 0.9940 to 0.9986. The recoveries of the method for the PAHs from water samples at spiking levels of 0.05 and 0.2 µg L(-1) ranged from 78.2% to 110.3%. Single fiber repeatability and fiber-to-fiber reproducibility were less than 9.3% and 13.8%, respectively. PMID:25127639

  14. Polydimethylsiloxane/metal-organic frameworks coated stir bar sorptive extraction coupled to gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in environmental water samples.

    PubMed

    Xiao, Zuowei; He, Man; Chen, Beibei; Hu, Bin

    2016-08-15

    In this work, the metal-organic frameworks (MOFs), MIL-101-Cr-NH2 was synthesized via a direct hydrothermal method, and a polydimethylsiloxane (PDMS)/MIL-101-Cr-NH2 coated stir bar was prepared by sol-gel technique. Good reproducibility was obtained for the preparation of PDMS/MIL-101-Cr-NH2 coated stir bar with the relative standard deviations (RSDs) ranging from 3.7 to 5.2% (n=7) in one batch, and from 5.4 to 9.2% (n=7) among different batches. With the high surface area and rich benzene ring structure of MIL-101-Cr-NH2, the prepared PDMS/MIL-101-Cr-NH2 coated stir bar presented higher extraction efficiency for target organophosphorus pesticides (OPPs, including phorate, diazinon, malathion, fenthion, quinalphos and ethion) over PDMS coated stir bar. Based on it, a new method of PDMS/MIL-101-Cr-NH2 coated stir bar sorptive extraction (SBSE) coupled to gas chromatography-flame photometric detection (GC-FPD) was proposed for the determination of six OPPs in environmental water samples. The operation parameters affecting the extraction efficiency of SBSE, including extraction time, stirring rate, desorption time and ionic strength, were investigated. Under the optimal conditions, the limits of detection (S/N=3) were found to be in the range of 0.043-0.085μgL(-1) for the six target OPPs, and the linear range was 0.5-100μgL(-1) for malathion and 0.2-100μgL(-1) for other five OPPs. The RSDs of the proposed method evaluated at 1µgL(-1) for each OPP were in the range of 5.9-8.7% (intra-day, n=7) and 6.1-10.7% (inter-day, n=5), respectively. The enrichment factors were varied from 110 to 151-fold (theoretical enrichment factor was 200-fold). The proposed method was applied to the analysis of OPPs in East Lake and pond water samples with recoveries in the range of 89.3-115% and 80.0-113% for the spiked East Lake and pond water samples, respectively. PMID:27260444

  15. Micromachining of polydimethylsiloxane induced by laser plasma EUV light

    NASA Astrophysics Data System (ADS)

    Torii, S.; Makimura, T.; Okazaki, K.; Nakamura, D.; Takahashi, A.; Okada, T.; Niino, H.; Murakami, K.

    2011-06-01

    Polydimethylsiloxane (PDMS) is fundamental materials in the field of biotechnology. Because of its biocompatibility, microfabricated PDMS sheets are applied to micro-reactors and microchips for cell culture. Conventionally, the microstructures were fabricated by means of cast or imprint using molds, however it is difficult to fabricate the structures at high aspect ratios such as through-holes/vertical channels. The fabrication of the high-aspect structures would enable us to stack sheets to realize 3D fluidic circuits. In order to achieve the micromachining, direct photo-ablation by short wavelength light is promising. In the previous works, we investigated ablation of transparent materials such as silica glass and poly(methyl methacrylate) induced by irradiation with laser plasma EUV light. We achieved smooth and fine nanomachining. In this work, we applied our technique to PDMS micromachining. We condensed the EUV light onto PDMS surfaces at high power density up to 108 W/cm2 using a Au coated ellipsoidal mirror. We found that PDMS sheet was ablated at a rate up to 440 nm/shot. It should be emphasized that through hole with a diameter of 1 μm was fabricated in a PDMS sheet with a thickness of 4 μm. Thus we demonstrated the micromachining of PDMS sheets using laser plasma EUV light.

  16. Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples.

    PubMed

    Zhong, Cheng; He, Man; Liao, Huaping; Chen, Beibei; Wang, Cheng; Hu, Bin

    2016-04-01

    In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively. PMID:26961915

  17. Integration of continuous-flow sampling with microchip electrophoresis using poly(dimethylsiloxane)-based valves in a reversibly sealed device.

    PubMed

    Li, Michelle W; Martin, R Scott

    2007-07-01

    Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39 nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n = 10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90 s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions. PMID:17577199

  18. Acupuncture Sample Injection for Microchip Capillary Electrophoresis and Electrokinetic Chromatography.

    PubMed

    Ha, Ji Won; Hahn, Jong Hoon

    2016-05-01

    A simple nanoliter-scale injection technique was developed for polydimethylsiloxane (PDMS) microfluidic devices to form the well-defined sample plugs in microfluidic channels. Sample injection was achieved by performing acupuncture on a channel with a needle and applying external pressure to a syringe. This technique allowed us to achieve reproducible injection of a 3-nL segment into a microchannel for PDMS microchip-based capillary electrophoresis (CE). Capillary zone electrophoresis (CZE) and capillary electrochromatography (CEC) with bead packing were successfully performed by applying a single potential in the most simplified straight channel. The advantages of this acupuncture injection over the electrokinetic injection in microchip CE include capability of minimizing sample loss and voltage control hardware, capability of serial injections of different sample solutions into a same microchannel, capability of injecting sample plugs into any position of a microchannel, independence on sample solutions during the loading step, and ease in making microchips due to the straight channel, etc. PMID:27056036

  19. Acoustothermal heating of polydimethylsiloxane microfluidic system.

    PubMed

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

    2015-01-01

    We report an observation of rapid (exceeding 2,000 K/s) heating of polydimethylsiloxane (PDMS), one of the most popular microchannel materials, under cyclic loadings at high (~MHz) frequencies. A microheater was developed based on the finding. The heating mechanism utilized vibration damping in PDMS induced by sound waves that were generated and precisely controlled using a conventional surface acoustic wave (SAW) microfluidic system. The refraction of SAW into the PDMS microchip, called the leaky SAW, takes a form of bulk wave and rapidly heats the microchannels in a volumetric manner. The penetration depths were measured to range from 210 μm to 1290 μm, enough to cover most sizes of microchannels. The energy conversion efficiency was SAW frequency-dependent and measured to be the highest at around 30 MHz. Independent actuation of each interdigital transducer (IDT) enabled independent manipulation of SAWs, permitting spatiotemporal control of temperature on the microchip. All the advantages of this microheater facilitated a two-step continuous flow polymerase chain reaction (CFPCR) to achieve the billion-fold amplification of a 134 bp DNA amplicon in less than 3 min. PMID:26138310

  20. Acoustothermal heating of polydimethylsiloxane microfluidic system

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  1. Acoustothermal heating of polydimethylsiloxane microfluidic system

    PubMed Central

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

    2015-01-01

    We report an observation of rapid (exceeding 2,000 K/s) heating of polydimethylsiloxane (PDMS), one of the most popular microchannel materials, under cyclic loadings at high (~MHz) frequencies. A microheater was developed based on the finding. The heating mechanism utilized vibration damping in PDMS induced by sound waves that were generated and precisely controlled using a conventional surface acoustic wave (SAW) microfluidic system. The refraction of SAW into the PDMS microchip, called the leaky SAW, takes a form of bulk wave and rapidly heats the microchannels in a volumetric manner. The penetration depths were measured to range from 210 μm to 1290 μm, enough to cover most sizes of microchannels. The energy conversion efficiency was SAW frequency-dependent and measured to be the highest at around 30 MHz. Independent actuation of each interdigital transducer (IDT) enabled independent manipulation of SAWs, permitting spatiotemporal control of temperature on the microchip. All the advantages of this microheater facilitated a two-step continuous flow polymerase chain reaction (CFPCR) to achieve the billion-fold amplification of a 134 bp DNA amplicon in less than 3 min. PMID:26138310

  2. Design and Fabrication of a PDMS Microchip Based Immunoassay

    SciTech Connect

    Shao, Guocheng; Wang, Wanjun; Wang, Jun; Lin, Yuehe

    2010-07-01

    In this paper, we describe the design and fabrication process of a polydimethylsiloxane (PDMS) microchip for on-chip multiplex immunoassay application. The microchip consists of a PDMS microfluidic channel layer and a micro pneumatic valve control layer. By selectively pressurizing the pneumatic microvalves, immuno reagents were controlled to flow and react in certain fluidic channel sites. Cross contamination was prevented by tightly closed valves. Our design was proposed to utilize PDMS micro channel surface as the solid phase immunoassay substrate and simultaneously detect four targets antigens on chip. Experiment result shows that 20psi valve pressure is sufficient to tightly close a 200µm wide micro channel with flow rate up to 20µl/min.

  3. Red microchip VECSEL array

    NASA Astrophysics Data System (ADS)

    Hastie, Jennifer E.; Morton, Lynne G.; Calvez, Stephane; Dawson, Martin D.; Leinonen, Tomi; Pessa, Markus; Gibson, Graham; Padgett, Miles J.

    2005-09-01

    We report an InGaP/AlInGaP/GaAs microchip vertical-external-cavity surface emitting laser operating directly at red wavelengths and demonstrate its potential for array-format operation. Optical pumping with up to 3.3W at 532nm produced a maximum output power of 330mW at 675nm, in a single circularly-symmetric beam with M2<2. Simultaneous pumping with three separate input beams, generated using a diffractive optical element, achieved lasing from three discrete areas of the same chip. Output power of ~95mW per beam was obtained from this 3x1 array, each beam having a Gaussian intensity profile with M2<1.2. In a further development, a spatial light modulator allowed computer control over the orientation and separation of the pump beams, and hence dynamic control over the configuration of the VECSEL array.

  4. Red microchip VECSEL array.

    PubMed

    Hastie, Jennifer; Morton, Lynne; Calvez, Stephane; Dawson, Martin; Leinonen, Tomi; Pessa, Markus; Gibson, Graham; Padgett, Miles

    2005-09-01

    We report an InGaP/AlInGaP/GaAs microchip vertical-external-cavity surface emitting laser operating directly at red wavelengths and demonstrate its potential for array-format operation. Optical pumping with up to 3.3W at 532nm produced a maximum output power of 330mW at 675nm, in a single circularly-symmetric beam with M2<2. Simultaneous pumping with three separate input beams, generated using a diffractive optical element, achieved lasing from three discrete areas of the same chip. Output power of ~95mW per beam was obtained from this 3x1 array, each beam having a Gaussian intensity profile with M2<1.2. In a further development, a spatial light modulator allowed computer control over the orientation and separation of the pump beams, and hence dynamic control over the configuration of the VECSEL array. PMID:19498743

  5. A novel polydimethylsiloxane microfluidic viscometer fabricated using microwire-molding

    NASA Astrophysics Data System (ADS)

    Zou, Misha; Cai, Shaoxi; Zhao, Zhenli; Chen, Longcong; Zhao, Yi; Fan, Xin; Chen, Sijia

    2015-10-01

    We present a new economical microfluidic viscometer to measure the viscosity of biological fluids, using sample volumes of less than 200 μl. It is fabricated using a microwire-molding technique, making it easier and cheaper to produce than existing viscometers. The viscometer is based on laminar flow inside a polydimethylsiloxane microchip. The velocity of the sample flow inside the capillary was monitored with a camera, and the movement of the liquid column was determined by a Matlab video-processing program. The device was calibrated using deionized water, which is a Newtonian fluid, at 20 °C. The viscometer provides accurate measurements of viscosity for values as small as 0.69 mPa s. The viscosity of water at different temperatures was measured, showing more than 98% agreement with the values provided by the National Institute of Standards and Technology. Various samples including a series of glycerol solutions, phosphate-buffered saline, alcohol, and cell media were also tested, and the measured viscosities were compared with those from a traditional glass capillary viscometer. The results show good agreement between the two methods, with an average relative error of less than 1%. Furthermore, the viscosities of several cell suspensions were measured, showing a relative standard deviation of less than 1.5%. The microchip viscometer is economical and is shown to be accurate, which is very important for the simulation and control of lab-on-a-chip experiments.

  6. A novel polydimethylsiloxane microfluidic viscometer fabricated using microwire-molding.

    PubMed

    Zou, Misha; Cai, Shaoxi; Zhao, Zhenli; Chen, Longcong; Zhao, Yi; Fan, Xin; Chen, Sijia

    2015-10-01

    We present a new economical microfluidic viscometer to measure the viscosity of biological fluids, using sample volumes of less than 200 μl. It is fabricated using a microwire-molding technique, making it easier and cheaper to produce than existing viscometers. The viscometer is based on laminar flow inside a polydimethylsiloxane microchip. The velocity of the sample flow inside the capillary was monitored with a camera, and the movement of the liquid column was determined by a Matlab video-processing program. The device was calibrated using deionized water, which is a Newtonian fluid, at 20 °C. The viscometer provides accurate measurements of viscosity for values as small as 0.69 mPa s. The viscosity of water at different temperatures was measured, showing more than 98% agreement with the values provided by the National Institute of Standards and Technology. Various samples including a series of glycerol solutions, phosphate-buffered saline, alcohol, and cell media were also tested, and the measured viscosities were compared with those from a traditional glass capillary viscometer. The results show good agreement between the two methods, with an average relative error of less than 1%. Furthermore, the viscosities of several cell suspensions were measured, showing a relative standard deviation of less than 1.5%. The microchip viscometer is economical and is shown to be accurate, which is very important for the simulation and control of lab-on-a-chip experiments. PMID:26520971

  7. Application of poly(dimethylsiloxane) fiber sol-gel coated onto NiTi alloy electrodeposited with zirconium oxide for the determination of organochlorine pesticides in herbal infusions.

    PubMed

    Budziak, Dilma; Martendal, Edmar; Carasek, Eduardo

    2008-08-01

    A PDMS fiber sol-gel coated onto an NiTi alloy previously electrodeposited with zirconium oxide (named NiTi-ZrO(2)-PDMS) was applied to the determination of organochlorine pesticides (OCPs) in infusions of peppermint (Mentha piperita L.), lemon grass (Cymbopogon citratus Stapf), chamomile (Matricaria recutita L.), lemon balm (Melissa officinalis L.), and anise seeds (Pimpinella anisum L.). Salting-out effect, extraction time, and extraction temperature were optimized firstly by means of a full-factorial design and then using a Doehlert matrix. No salt addition and 50 min of extraction at 70 degrees C were the optimum conditions. Satisfactory LODs in the range of 2-17 ng/L, as well as good correlation coefficients (at least 0.9981) in the linear range studied, were obtained. Calibration was successfully applied using an infusion of M. recutita L. and recovery tests were performed to ensure the accuracy of the method, with values in the range of 77-120%. Comparison of the NiTi-ZrO(2)-PDMS with commercially available PDMS fibers showed that the proposed fiber has an extraction efficiency comparable to that of PDMS 30 microm for the compounds evaluated, demonstrating its potential applicability. PMID:18666186

  8. Microchip problems plague DOD

    NASA Astrophysics Data System (ADS)

    Smith, R. J.

    1984-10-01

    The major issues in the controversy over the discovery of millions of defective microchips sold to the DOD by the Texas Instruments (TI) corporation are outlined. Defects in the microcircuits are blamed on inadequate testing procedures performed by TI during manufacture, and on inadequate testing procedures used by a subcontractor especially contracted to test the chips. Because the problem persisted over a period of years, defects might be possible in as many as 100 million chips used in a broad range of military applications including the Trident submarine, the B-52, B-1B, F-15, F-111, F-4, A-6, and A-7 aircraft, the Harpoon and HARM missile systems, and the Space Shuttles Discovery and Challenger. It is pointed out that although TI has accepted responsibility for the defective chips, little will be done by the DOD to compel the company to replace them, or to upgrade testing procedures. It is concluded that the serious nature of the problem could renew interest in recommendations for the standardization of military microcircuits.

  9. Hydrodynamic injection with pneumatic valving for microchip electrophoresis with total analyte utilization

    SciTech Connect

    Sun, Xuefei; Kelly, Ryan T.; Danielson, William F.; Agrawal, Nitin; Tang, Keqi; Smith, Richard D.

    2011-04-26

    A novel hydrodynamic injector that is directly controlled by a pneumatic valve has been developed for reproducible microchip capillary electrophoresis (CE) separations. The poly(dimethylsiloxane) (PDMS) devices used for evaluation comprise a separation channel, a side channel for sample introduction, and a pneumatic valve aligned at the intersection of the channels. A low pressure (≤ 3 psi) applied to the sample reservoir is sufficient to drive sample into the separation channel. The rapidly actuated pneumatic valve enables injection of discrete sample plugs as small as ~100 pL for CE separation. The injection volume can be easily controlled by adjusting the intersection geometry, the solution back pressure and the valve actuation time. Sample injection could be reliably operated at different frequencies (< 0.1 Hz to >2 Hz) with good reproducibility (peak height relative standard deviation ≤ 3.6%) and no sampling biases associated with the conventional electrokinetic injections. The separation channel was dynamically coated with a cationic polymer, and FITC-labeled amino acids were employed to evaluate the CE separation. Highly efficient (≥ 7.0 × 103 theoretical plates for the ~2.4 cm long channel) and reproducible CE separations were obtained. The demonstrated method has numerous advantages compared with the conventional techniques, including repeatable and unbiased injections, no sample waste, high duty cycle, controllable injected sample volume, and fewer electrodes with no need for voltage switching. The prospects of implementing this injection method for coupling multidimensional separations, for multiplexing CE separations and for sample-limited bioanalyses are discussed.

  10. Elastomeric Microchip Electrospray Emitter for Stable Cone-Jet Mode Operation in the Nanoflow Regime.

    SciTech Connect

    Kelly, Ryan T.; Tang, Keqi; Irimia, Daniel; Toner, Mehmet; Smith, Richard D.

    2008-05-15

    Despite widespread interest in applying lab-on-a-chip technologies to mass spectrometry (MS)-based analyses, the coupling of microfluidics to electrospray ionization (ESI)-MS remains challenging. We report a robust, integrated poly(dimethylsiloxane) microchip interface for ESI-MS using simple and widely accessible microfabrication procedures. The interface uses an auxiliary channel to provide electrical contact in the Taylor cone of the electrospray without sample loss or dilution. The electric field at the channel terminus is enhanced by two vertical cuts that cause the interface to taper to a line rather than to a point, and the formation of small Taylor cones at the channel exit ensures sub-nL post-column dead volumes. While comparable ESI-MS sensitivities were achieved using both microchip and conventional fused silica capillary emitters, stable cone-jet mode electrospray could be established over a far broader range of flow rates (from 50–1000 nL/min) and applied potentials using the microchip emitters. This special feature of the microchip emitter should minimize the fine tuning required for electrospray optimization and make the stable electrospray more resistant to external perturbations.

  11. Analytical Chemistry and the Microchip.

    ERIC Educational Resources Information Center

    Lowry, Robert K.

    1986-01-01

    Analytical techniques used at various points in making microchips are described. They include: Fourier transform infrared spectrometry (silicon purity); optical emission spectroscopy (quantitative thin-film composition); X-ray photoelectron spectroscopy (chemical changes in thin films); wet chemistry, instrumental analysis (process chemicals);…

  12. Integration of ground aerogel particles as chromatographic stationary phase into microchip.

    PubMed

    Gaspar, Attila; Nagy, Andrea; Lazar, Istvan

    2011-02-18

    C16 modified and ground monolithic silica aerogel particles in submicrometer size, as a new type of stationary phase was prepared and integrated in polydimethylsiloxane (PDMS) microchip. The aerogel particles were packed into the microfluidic channel using a simple procedure, which does not require any special frit or fabrication step to retain the particles. The subnanoliter volume of samples can be transported through the porous, short length of packing with low pressure (< 3 bar). Food dyes as test components could be separated using low pressure within 6s. A 50-fold preconcentration could be achieved by retaining 100 nL volume of sample on the packing and elution with methanol. PMID:21227431

  13. DNA analysis and diagnostics on oligonucleotide microchips.

    PubMed Central

    Yershov, G; Barsky, V; Belgovskiy, A; Kirillov, E; Kreindlin, E; Ivanov, I; Parinov, S; Guschin, D; Drobishev, A; Dubiley, S; Mirzabekov, A

    1996-01-01

    We present a further development in the technology of sequencing by hybridization to oligonucleotide microchips (SHOM) and its application to diagnostics for genetic diseases. A robot has been constructed to manufacture sequencing "microchips." The microchip is an array of oligonucleotides immobilized into gel elements fixed on a glass plate. Hybridization of the microchip with fluorescently labeled DNA was monitored in real time simultaneously for all microchip elements with a two-wavelength fluorescent microscope equipped with a charge-coupled device camera. SHOM has been used to detect beta-thalassemia mutations in patients by hybridizing PCR-amplified DNA with the microchips. A contiguous stacking hybridization technique has been applied for the detection of mutations; it can simplify medical diagnostics and enhance its reliability. The use of multicolor monitoring of contiguous stacking hybridization is suggested for large-scale diagnostics and gene polymorphism studies. Other applications of the SHOM technology are discussed. Images Fig. 2 Fig. 3 Fig. 4 PMID:8643503

  14. Biological cell controllable patch-clamp microchip

    NASA Astrophysics Data System (ADS)

    Penmetsa, Siva; Nagrajan, Krithika; Gong, Zhongcheng; Mills, David; Que, Long

    2010-12-01

    A patch-clamp (PC) microchip with cell sorting and positioning functions is reported, which can avoid drawbacks of random cell selection or positioning for a PC microchip. The cell sorting and positioning are enabled by air bubble (AB) actuators. AB actuators are pneumatic actuators, in which air pressure is generated by microheaters within sealed microchambers. The sorting, positioning, and capturing of 3T3 cells by this type of microchip have been demonstrated. Using human breast cancer cells MDA-MB-231 as the model, experiments have been demonstrated by this microchip as a label-free technical platform for real-time monitoring of the cell viability.

  15. Particle-free microchip processing

    DOEpatents

    Geller, A.S.; Rader, D.J.

    1996-06-04

    Method and apparatus for reducing particulate contamination in microchip processing are disclosed. The method and apparatus comprise means to reduce particle velocity toward the wafer before the particles can be deposited on the wafer surface. A reactor using electric fields to reduce particle velocity and prevent particulate contamination is disclosed. A reactor using a porous showerhead to reduce particle velocities and prevent particulate contamination is disclosed. 5 figs.

  16. Particle-free microchip processing

    DOEpatents

    Geller, Anthony S.; Rader, Daniel J.

    1996-01-01

    Method and apparatus for reducing particulate contamination in microchip processing are disclosed. The method and apparatus comprise means to reduce particle velocity toward the wafer before the particles can be deposited on the wafer surface. A reactor using electric fields to reduce particle velocity and prevent particulate contamination is disclosed. A reactor using a porous showerhead to reduce particle velocities and prevent particulate contamination is disclosed.

  17. Cost-effective neutral density filters from polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Amarit, Ratthasart; Chaitavon, Kosom; Sumriddetchkajorn, Sarun

    2013-06-01

    A neutral density filter (ND) is one of the basic and important optical components used in optical and photographic systems for controlling intensity of light at all wavelengths. It is typically fabricated by coating appropriate thin films on glass or plastic substrates through an expensive time-consuming and power-hungry thin-film coating system. In this work, we show for the first time how very low-cost NDs can be implemented on a well-known Polydimethylsiloxane (PDMS) material widely used in microfluidic applications. PDMS-based NDs with 10-80% transmission and a broad wavelength operation in a visible spectrum are highlighted.

  18. Production of Microchips from Polystyrene Plates

    ERIC Educational Resources Information Center

    Pace, Sarah Lindsey

    2009-01-01

    Currently manufactured microchips are expensive to make, require specialized equipment, and leave a large environmental footprint. To counter this, an alternative procedure that is cheaper and leaves a smaller environmental footprint should be made. The goal of this research project is to develop a process that creates microchips from polystyrene…

  19. Microchips in Medicine: Current and Future Applications

    PubMed Central

    Eltorai, Adam E. M.; Fox, Henry; McGurrin, Emily; Guang, Stephanie

    2016-01-01

    With the objective of improving efficacy and morbidity, device manufacturers incorporate chemicals or drugs into medical implants. Using multiple reservoirs of discrete drug doses, microchips represent a new technology capable of on-demand release of various drugs over long periods of time. Herein, we review drug delivery systems, how microchips work, recent investigations, and future applications in various fields of medicine. PMID:27376079

  20. Homogeneous agglutination assay based on micro-chip sheathless flow cytometry.

    PubMed

    Ma, Zengshuai; Zhang, Pan; Cheng, Yinuo; Xie, Shuai; Zhang, Shuai; Ye, Xiongying

    2015-11-01

    Homogeneous assays possess important advantages that no washing or physical separation is required, contributing to robust protocols and easy implementation which ensures potential point-of-care applications. Optimizing the detection strategy to reduce the number of reagents used and simplify the detection device is desirable. A method of homogeneous bead-agglutination assay based on micro-chip sheathless flow cytometry has been developed. The detection processes include mixing the capture-probe conjugated beads with an analyte containing sample, followed by flowing the reaction mixtures through the micro-chip sheathless flow cytometric device. The analyte concentrations were detected by counting the proportion of monomers in the reaction mixtures. Streptavidin-coated magnetic beads and biotinylated bovine serum albumin (bBSA) were used as a model system to verify the method, and detection limits of 0.15 pM and 1.5 pM for bBSA were achieved, using commercial Calibur and the developed micro-chip sheathless flow cytometric device, respectively. The setup of the micro-chip sheathless flow cytometric device is significantly simple; meanwhile, the system maintains relatively high sensitivity, which mainly benefits from the application of forward scattering to distinguish aggregates from monomers. The micro-chip sheathless flow cytometric device for bead agglutination detection provides us with a promising method for versatile immunoassays on microfluidic platforms. PMID:26649133

  1. Underivatized cyclic olefin copolymer as substrate material and stationary phase for capillary and microchip electrochromatography.

    PubMed

    Gustafsson, Omar; Mogensen, Klaus B; Kutter, Jörg P

    2008-08-01

    We report, for the first time, the use of underivatized cyclic olefin copolymer (COC, more specifically: Topas) as the substrate material and the stationary phase for capillary and microchip electrochromatography (CEC), and demonstrate chromatographic separations without the need of coating procedures. Electroosmotic mobility measurements in a 25 microm id Topas capillary showed a significant cathodic EOF that is pH-dependent. The magnitude of the electroosmotic mobility is comparable to that found in glass substrates and other polymeric materials. Open-tubular CEC was employed to baseline-separate three neutral compounds in an underivatized Topas capillary with plate heights ranging from 5.3 to 12.7 microm. The analytes were detected using UV absorbance at 254 nm, thus taking advantage of the optical transparency of Topas at short wavelengths. The fabrication of a Topas-based electrochromatography microchip by nanoimprint lithography is also presented. The microchip has an array of pillars in the separation column to increase the surface area. The smallest features that were successfully imprinted were around 2 microm wide and 5 microm high. No plasma treatment was used during the bonding, thus keeping the surface properties of the native material. An RP microchip electrochromatography separation of three fluorescently labeled amines is demonstrated on the underivatized microchip with plate heights ranging from 3.4 to 22 microm. PMID:18618461

  2. Downstream microwave ammonia plasma treatment of polydimethylsiloxane

    SciTech Connect

    Pruden, K.G.; Beaudoin, S.P.

    2005-01-01

    To control the interactions between surfaces and biological systems, it is common to attach polymers, proteins, and other species to the surfaces of interest. In this case, surface modification of polydimethylsiloxane (PDMS) was performed by exposing PDMS films to the effluent from a microwave ammonia plasma, with a goal of creating primary amine groups on the PDMS. These amine sites were to be used as binding sites for polymer attachment. Chemical changes to the surface of the PDMS were investigated as a function of treatment time, microwave power, and PDMS temperature during plasma treatment. Functional groups resulting from this treatment were characterized using attenuated total reflectance infrared spectroscopy. Plasma treatment resulted in the incorporation of oxygen- and nitrogen-containing groups, including primary amine groups. In general, increasing the treatment time, plasma power and substrate temperature increased the level of oxidation of the films, and led to the formation of imines and nitriles. PDMS samples treated at 100 W and 23 deg. C for 120 s were chosen for proof-of-concept dextran coating. Samples treated at this condition contained primary amine groups and few oxygen-containing groups. To test the viability of the primary amines for attachment of biopolymers, functionalized dextran was successfully attached to primary amine sites on the PDMS films.

  3. Measurement of Nitrogen Mustard Degredation Products by Poly(dimethylsiloxane) Microchip Electrophoresis with Contactless Conductivity Detection

    EPA Science Inventory

    The potential risk of human exposure from an accidental or intentional release of CWAs into a civilian population continues to drive the need for screening and monitoring techniques for these compounds. In particular, rapid and reliable methods for detecting CWAs such as the nitr...

  4. Electrohydrodynamic generation and delivery of monodisperse picoliter droplets using a poly(dimethylsiloxane) microchip.

    PubMed

    Kim, Sung Jae; Song, Yong-Ak; Skipper, Paul L; Han, Jongyoon

    2006-12-01

    We developed a drop-on-demand microdroplet generator for the discrete dispensing of biosamples into a bioanalytical unit. This disposable PDMS microfluidic device can generate monodisperse droplets of picoliter volume directly out of a plane sidewall of the microfluidic chip by an electrohydrodynamic mechanism. The droplet generation was accomplished without using either an inserted capillary or a monolithically built-in tip. The minimum droplet volume was approximately 4 pL, and the droplet generation was repeatable and stable for at least 30 min, with a typical variation of less than 2.0% of drop size. The Taylor cone, which is usually observed in electrospray, was suppressed by controlling the surface wetting property of the PDMS device as well as the surface tension of the sample liquids. A modification of the channel geometry right before the opening of the microchannel also enhanced the continuous droplet generation without applying any external pumping. A simple numerical simulation of the droplet generation verified the importance of controlling the surface wetting conditions for the droplet formation. Our microdroplet generator can be effectively applied to a direct interface of a microfluidic chip to a biosensing unit, such as AMS, MALDI-MS or protein microarray-type biochips. PMID:17134134

  5. Infrared dielectric function of polydimethylsiloxane and selective emission behavior

    NASA Astrophysics Data System (ADS)

    Srinivasan, Arvind; Czapla, Braden; Mayo, Jeff; Narayanaswamy, Arvind

    2016-08-01

    The complex refractive index of polydimethylsiloxane (PDMS) is determined in the wavelength range between 2.5 μm and 16.7 μm. The parameters of a Drude-Lorentz oscillator model (with 15 oscillators) are extracted from Fourier transform infrared spectroscopy reflectance measurements made on both bulk PDMS and thin films of PDMS deposited on the gold coated silicon substrates. It is shown that thin films of PDMS atop gold exhibit selective emission in the 8 μm to 13 μm atmospheric transmittance window, which demonstrates that PDMS, especially due to its ease of deposition, may be a viable material for passive radiative cooling applications.

  6. Microbioassay system for antiallergic drug screening using suspension cells retaining in a poly(dimethylsiloxane) microfluidic device.

    PubMed

    Tokuyama, Takahito; Fujii, Shin-Ichiro; Sato, Kiichi; Abo, Mitsuru; Okubo, Akira

    2005-05-15

    This article describes an antiallergic drug-screening system by the detection of histamine released from mast cells (suspension cells) on a multilayer microchip. In this study, the elastmeric material, poly(dimethylsiloxane) (PDMS), was employed to fabricate microchannels and microchambers. The microchip consists of two sections: a histamine-releasing one, which has a cell chamber, and a histamine-derivatizing one. Both were laminated to one microchip. Rat peritoneal mast cells were retained in the cell chamber (1.2 microL) with a filtering system using a cellulose nitrate membrane. This filtering system could easily retain suspension cells without cell damage. Mast cells were viable for a sufficient time to conduct the assay on the cell chamber. The cells were stimulated with a chemical release compound 48/80 (C48/80), and then histamine flowed into the lower layer, where it was derivatized to the fluorescent molecules with o-phthalaldehyde and its fluorescence was detected on the microchip. This flow system could detect the time course of the histamine release, and this microchip system required only 20 min for the assay. By this integrated system, 51 pmol of histamine released from 500 cells was detected, and the number of cells required for the assay was reduced to 1% compared with conventional bulk systems. By comparing the released histamine levels with and without drugs, their effect could be evaluated. The inhibition ratio of C48/80 induced-histamine release using an antiallergic drug, disodium cromoglicate (DSCG), was related to the concentration of DSCG. This flow system was applicable for antiallergy drug screening by rapid measurement of the inhibition of histamine release from a very small amount of mast cells. PMID:15889923

  7. Defense program pushes microchip frontiers

    NASA Astrophysics Data System (ADS)

    Julian, K.

    1985-05-01

    The very-high-speed integrated circuit (VHSIC) program of the Department of Defense will have a significant effect on the expansion of integrated circuit technology. This program, which is to cost several hundred million dollars, is accelerating the trend toward higher-speed, denser circuitry for microchips through innovative design and fabrication techniques. Teams in six different American companies are to design and fabricate a military useful 'brassboard' system which would employ chips developed in the first phase of the VHSIC program. Military objectives envisaged include automatic monitoring of displays in tactical aircraft by means of an artificial intelligence system, a brassboard used in airborne electronic warfare system, and antisubmarine warfare applications. After a fivefold improvement in performance achieved in the first phase, the second phase is concerned with a further 20-fold increase. The entire VHSIC program is, therefore, to produce a 100-fold gain over the state of the art found when the program started.

  8. Microchip-based immunomagnetic detection of circulating tumor cells.

    PubMed

    Hoshino, Kazunori; Huang, Yu-Yen; Lane, Nancy; Huebschman, Michael; Uhr, Jonathan W; Frenkel, Eugene P; Zhang, Xiaojing

    2011-10-21

    Screening for circulating tumor cells (CTCs) in blood has been an object of interest for evidence of progressive disease, status of disease activity, recognition of clonal evolution of molecular changes and for possible early diagnosis of cancer. We describe a new method of microchip-based immunomagnetic CTC detection, in which the benefits of both immunomagnetic assay and the microfluidic device are combined. As the blood sample flows through the microchannel closely above arrayed magnets, cancer cells labeled with magnetic nanoparticles are separated from blood flow and deposited at the bottom wall of the glass coverslip, which allows direct observation of captured cells with a fluorescence microscope. A polydimethylsiloxane (PDMS)-based microchannel fixed on a glass coverslip was used to screen blood samples. The thin, flat dimensions of the microchannel, combined with the sharp magnetic field gradient in the vicinity of arrayed magnets with alternate polarities, lead to an effective capture of labeled cells. Compared to the commercially available CellSearch™ system, fewer (25%) magnetic particles are required to achieve a comparable capture rate, while the screening speed (at an optimal blood flow rate of 10 mL h(-1)) is more than five times faster than those reported previously with a microchannel-based assay. For the screening experiment, blood drawn from healthy subjects into CellSave™ tubes was spiked with cultured cancer cell lines of COLO205 and SKBR3. The blood was then kept at room temperature for 48 hours before the screening, emulating the actual clinical cases of blood screening. Customized Fe(3)O(4) magnetic nanoparticles (Veridex Ferrofluid™) conjugated to anti-epithelial cell adhesion molecule (EpCAM) antibodies were introduced into the blood samples to label cancer cells, and the blood was then run through the microchip device to capture the labelled cells. After capture, the cells were stained with fluorescent labelled anti

  9. Contact solid-phase microextraction with uncoated glass and polydimethylsiloxane-coated fibers versus solvent sampling for the determination of hydrocarbons in adhesion secretions of Madagascar hissing cockroaches Gromphadorrhina portentosa (Blattodea) by gas chromatography-mass spectrometry.

    PubMed

    Gerhardt, Heike; Schmitt, Christian; Betz, Oliver; Albert, Klaus; Lämmerhofer, Michael

    2015-04-01

    Molecular profiles of adhesion secretions of Gromphadorrhina portentosa (Madagascar hissing cockroach, Blattodea) were investigated by gas chromatography mass spectrometry with particular focus on a comprehensive analysis of linear and branched hydrocarbons. For this purpose, secretions from the tarsi (feet), possibly contributing to adhesion on smooth surfaces, and control samples taken from the tibiae (lower legs), which contain general cuticular hydrocarbons that are supposed to be not involved in the biological adhesion function, were analyzed and their molecular fingerprints compared. A major analytical difficulty in such a study constitutes the representative, spatially controlled, precise and reproducible sampling from a living insect as well as the minute quantities of insect secretions on both tarsi and tibiae. Thus, three different in vivo sampling methods were compared in terms of sampling reproducibility and extraction efficiency by replicate measurement of samples from tarsi and tibiae. While contact solid-phase microextraction (SPME) with a polydimethylsiloxane (PDMS) fiber showed higher peak intensities, a self-made uncoated glass fiber had the best repeatability in contact-SPME sampling. Chromatographic profiles of these two contact-SPME sampling methods were statistically not significantly different. Inter-individual variances were larger than potentially existing minor differences in molecular patterns of distinct sampling methods. Sampling by solvent extraction was time consuming, showed lower sensitivities and was less reproducible. In general, sampling by contact-SPME with a cheap glass fiber turned out to be a viable alternative to PDMS-SPME sampling. Hydrocarbon patterns of the tarsal adhesion secretions were qualitatively similar to those of epicuticular hydrocarbon profiles of the tibiae. However, hydrocarbons were in general less abundant in tarsal secretions than secretions from tibiae. PMID:25728659

  10. Application of Microchip Electrophoresis for Clinical Tests

    NASA Astrophysics Data System (ADS)

    Yatsushiro, Shouki; Kataoka, Masatoshi

    Microchip electrophoresis has recently attracted much attention in the field of nuclear acid analysis due to its high efficiency, ease of operation, low consumption of samples and reagents, and relatively low costs. In addition, the analysis has expanded to an analytical field like not only the analysis of DNA but also the analysis of RNA, the protein, the sugar chain, and the cellular function, etc. In this report, we showed that high-performance monitoring systems for human blood glucose levels and α-amylase activity in human plasma using microchip electrophoresis.

  11. On-Campus Projects: Inventing a Microchip.

    ERIC Educational Resources Information Center

    Basta, Nicholas

    1985-01-01

    In response to growth of microelectronics and changes in microchip design/manufacturing technology, universities are supporting class projects for students. Approximately 50 schools now conduct such programs which have resulted from earlier National Science Foundation sponsorship. Major advantages for the students include designing experience,…

  12. An Easy-to-Use Polystyrene Microchip-based Cell Culture System.

    PubMed

    Tazawa, Hidekatsu; Sunaoshi, Shohei; Tokeshi, Manabu; Kitamori, Takehiko; Ohtani-Kaneko, Ritsuko

    2016-01-01

    In this study, we developed an integrated, low-cost microfluidic cell culture system that is easy to use. This system consists of a disposable polystyrene microchip, a polytetrafluoroethylene valve, an air bubble trap, and an indium tin oxide temperature controller. Valve pressure resistance was validated with a manometer to be 3 MPa. The trap protected against bubble contamination. The temperature controller enabled the culture of Macaca mulatta RF/6A 135 vascular endothelial cells, which are difficult to culture in glass microchips, without a CO2 incubator. We determined the optimal coating conditions for these cells and were able to achieve stable, confluent culture within 1 week. This practical system is suitable for low-cost screening and has potential applications as circulatory cell culture systems and research platforms in cell biology. PMID:26960617

  13. Extrinsic Fabry-Perot interferometry for noncontact temperature control of nanoliter-volume enzymatic reactions in glass microchips.

    PubMed

    Easley, Christopher J; Legendre, Lindsay A; Roper, Michael G; Wavering, Thomas A; Ferrance, Jerome P; Landers, James P

    2005-02-15

    Optical fiber extrinsic Fabry-Perot interferometry (EFPI) was investigated as a noncontact temperature sensor and utilized for regulating the temperature of small-volume solutions in microchips. Interference pattern analysis determined the optical path lengths (OPL) associated with reflections from various surfaces on or in the microchip, in particular, from gold sputtered on the bottom of a microchannel. Since OPL is directly proportional to refractive index, which is dependent on solution temperature, the EFPI sensor was capable of noncontact monitoring of solution temperature simply from alterations in the measured path length. Calibration of the sensor against a thermocouple was performed while heating the microchip in a noncontact manner with an IR lamp. The combination of EFPI temperature sensor, IR-mediated heating, and air cooling allowed a fully noncontact system for small-volume temperature control in microchip structures, and its utility was illustrated by optimal digestion of DNA by a temperature-dependent restriction endonuclease in 320 nL. The functionality and simplicity of the microchip EFPI temperature sensor was enhanced by replacing the prebonding sputtered gold with a tunable, chemically plated semireflective silver coating created in situ after chip fabrication. This provided an 8-fold improvement in the lowest detectable temperature change (deltaT = 0.1 degrees C), facilitated primarily by enhanced reflection from both the bottom and top surfaces of the microchannel. This approach for controlling micro- and nanoscale reactions--with heating, cooling, and temperature control being carried out in a completely noncontact fashion--provides an accurate and sensitive method for executing chemical and biochemical reactions in microchips. PMID:15858983

  14. Capillary driven flow of polydimethylsiloxane in open rectangular microchannels.

    PubMed

    Sowers, Timothy W; Sarkar, Rohit; Eswarappa Prameela, Suhas; Izadi, Ehsan; Rajagopalan, Jagannathan

    2016-06-29

    The flow of liquid polydimethylsiloxane (PDMS, Dow Corning Sylgard 184, 10 : 1 base to cross-linker ratio) in open, rectangular silicon microchannels, with and without a coating (100 nm) of poly-tetra-fluoro-ethylene (PTFE), was studied. Photolithographic patterning and etching of silicon wafers was used to create microchannels with a range of widths (∼5-50 μm) and depths (5-20 μm). Experimental PDMS flow rates in both PTFE-coated and uncoated channels were compared to an analytical model based on the work of Lucas and Washburn. The experimental flow rates matched the predicted flow rates reasonably well when the channel aspect ratio (width to depth), p, was less than 2. For channels with p > 2, the observed flow rates progressively lagged model predictions with increasing p. The experimental data, including zero flow rates in certain high aspect ratio PTFE-coated channels, can largely be explained by changes in the front and upper meniscus morphology of the flow as the channel aspect ratio is varied. The results strongly suggest that meniscus morphology needs to be taken into account to accurately model capillary flow in microchannels, especially those with large aspect ratios. PMID:27301750

  15. Photometric flow injection determination of phosphate on a PDMS microchip using an optical detection system assembled with an organic light emitting diode and an organic photodiode.

    PubMed

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-01-01

    A compact photometric detector was constructed from an organic light emitting diode (OLED) based on a europium complex, europium(diben-zoylmethanato)3(bathophenanthroline) (Eu(DBM)3bath), as the light source and an organic photodiode (OPD) fabricated from a hetero-junction of two layers of copper phthalocyanine (CuPc)/fullerene (C60) as the photo-detector on a microchip prepared from poly(dimethylsiloxan) (PDMS) and was applied to the determination of phosphate. The OLED and the OPD were fabricated by a vapor deposition method on an indium tin oxide (ITO) coated glass substrate with the following layered structure; Glass (0.7 mm)/ITO (110 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl amino]-biphenyl (α-NPD) (30 nm)/4,4'-di(N-carbazolyl)biphenyl (CBP): Eu(3+) (8 wt%, 30 nm)/bathocuproine (BCP) (30 nm)/aluminum tris(8-hydroxyquinoline) (Alq3) (25 nm)/magnesium and silver (MgAg) (100 nm)/Ag (10nm) and Glass (0.7 mm)/ITO (110 nm)/CuPc (35 nm)/C60 (50 nm)/BCP (10 nm)/Ag (50 nm), respectively. The OLED based on the europium complex emitted a sharp light at the wavelength of 612 nm with a full width at half maximum (FWHM) of 8 nm. The performance of the photometric detector assembled was evaluated based on measurements of the absorbance of different concentrations of malachite green (MG) solutions for a batch system with 1cm long path length. The molar absorptive coefficient of the MG solution, calculated from the photocurrent of the OPD, was in good agreement with the value reported in the literature. A microchip with two inlets and one outlet U-shaped channel was prepared by a conventional photolithograph method. The OLED and the OPD were configured so as to face each other through the PDMS microchip in parallel in order to align the light axis of the OLED and the OPD with the flow cell (optical path length of 5mm), which was located at the end of outlet. For the determination of phosphate, an ion-association reaction between MG and a molybdenum-phosphate complex was utilized

  16. Microchip Capillary Electrophoresis with Electrochemical Detection for Monitoring Environmental Pollutants

    SciTech Connect

    Chen, Gang; Lin, Yuehe; Wang, Joseph

    2006-01-15

    This invited paper reviews recent advances and the key strategies in microchip capillary electrophoresis (CE) with electrochemical detection (ECD) for separating and detecting a variety of environmental pollutants. The subjects covered include the fabrication of microfluidic chips, sample pretreatments, ECD, typical applications of microchip CE with ECD in environmental analysis, and future prospects. It is expected that microchip CE-ECD will become a powerful tool in the environmental field and will lead to the creation of truly portable devices.

  17. A new method of marking dentures using microchips.

    PubMed

    Rajan, M; Julian, R

    2002-06-01

    Over the years various methods of denture marking have been reported in the literature. They include surface marking and inclusion techniques using metallic or non-metallic materials, microchips and microlabels. The microchips are preferred because of their small size and aesthetic acceptability. They are not however widely used due to the high cost of manufacture and data incorporation. This article details the procedures involved in inscribing a microchip using the photochemical etching process used in the electronics industry. The resulting microchip was cosmetically appealing, cost effective and was able to satisfy all the forensic requirements for a suitable denture marker. PMID:12085521

  18. Monitoring environmental pollutants by microchip capillary electrophoresis with electrochemical detection

    SciTech Connect

    Chen, Gang; Lin, Yuehe; Wang, Joseph

    2006-01-15

    This is a review article. During the past decade, significant progress in the development of miniaturized microfluidic systems has Occurred due to the numerous advantages of microchip analysis. This review focuses on recent advances and the key strategies in microchip capillary electrophoresis (CE) with electrochemical detection (ECD) for separating and detecting a variety of environmental pollutants. The subjects covered include the fabrication of microfluidic chips, ECD, typical applications of microchip CE with ECD in environmental analysis, and future prospects. It is expected that microchip CE-ECD will become a powerful tool in the environmental field and will lead to the creation of truly portable devices.

  19. Possibility of Microchip Electrophoresis for Biological Application

    NASA Astrophysics Data System (ADS)

    Kataoka, Masatoshi; Kido, Jun-Ichi; Shinohara, Yasuo

    Microchip electrophoresis has recently attracted much attention in the field of nuclear acid analysis due to its high efficiency, ease of operation, low consumption of samples and reagents, and relatively low costs. Nucleic acid fragments are separated by capillary electrophoresis in a chip with microfabricated channels, with automated detection as well as on-line data evaluation. Microfabricated devices are forecast to be fundamental to the postgenome era, especially in the field of genetics and medicine. However, although there are many reports of the use of these instruments to evaluate standard DNA, DNA ladders, PCR products, and commercially available plasmid digests, little information is available their use with biological material. In this report, we showed the accuracy of sizing and quantification of endonuclease-digested plasmid DNA. We also showed the feasibility of on-microchip endonuclease treatment of plasmid DNA and sequential analysis as an additional application for DNA analysis. Furthermore, to evaluate the possibility of microchip electrophoresis for biological application, the results of the examination of blood sugar in human plasma and mitochondrial membrane potential were shown.

  20. Fs-laser processing of polydimethylsiloxane

    SciTech Connect

    Atanasov, Petar A. Nedyalkov, Nikolay N.; Valova, Eugenia I.; Georgieva, Zhenya S.; Armyanov, Stefan A.; Kolev, Konstantin N.; Amoruso, Salvatore; Wang, Xuan; Bruzzese, Ricardo; Sawczak, Miroslaw; Śliwiński, Gerard

    2014-07-14

    We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263 nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and μ-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. μ-Raman spectra, carried out at both 514 and 785 nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observation with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.

  1. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  2. IATROGENIC MICROCHIP ARTERIAL EMBOLISM IN A CHILEAN FLAMINGO (PHOENICOPTERUS CHILENSIS).

    PubMed

    Olds, June E; Ewing, Jacob; Arruda, Paulo; Kuyper, Jennifer; Riedesel, Elizabeth; Miles, Kristina M

    2016-06-01

    Aberrant microchip migration has been reported in domestic animal species, but in most cases, this migration is atraumatic to the patient. Reports of microchip-associated trauma and sarcoma development also have been reported in a variety of mammal species. This report describes accidental arterial microchip insertion causing obstruction of the iliac artery in a Chilean flamingo (Phoenicopterus chilensis). Diagnostic imaging included digital radiography and pre- and post-contrast computed tomography to determine the location of the microchip. Surgical removal of the microchip was attempted; however, the flamingo died intraoperatively. Postmortem evaluation found trauma to the epicardium, without penetration of the ventricle. The descending aorta was found traumatized and identified as the most likely insertion point leading to the embolism. PMID:27468052

  3. Experiences with Hermann's tortoise (Testudo hermanni) microchipping in Slovenia - Short communication.

    PubMed

    Dovč, Alenka; Stvarnik, Mateja; Mavri, Urška; Gregurić-Gračner, Gordana; Tomažić, Iztok

    2016-03-01

    This study describes experiences obtained with microchipping of Hermann's tortoises in Slovenia. Over a period of three years, a total of 5,128 Hermann's tortoises from parental breeding stock were microchipped. Microchips were implanted subcutaneously in the left inguinal region. During the application of microchips, males were bleeding in 2.6% and females in 1.4% of the cases. Bleeding frequency was related to sex, animal size and environmental temperature at the time of microchipping. The presence of microchips was followed up over a period of several years. At the control check conducted a few years later, all previously microchipped tortoises were included. Out of the entire parental breeding stock, 235 (4.6%) had lost their microchips, thus 63 males (5.7%) and 172 females (4.3%) were unmarked. The possible reasons for microchip loss are migration or inactivity of the implanted microchips. PMID:26919141

  4. Readability and histological biocompatibility of microchip transponders in horses.

    PubMed

    Wulf, M; Wohlsein, P; Aurich, J E; Nees, M; Baumgärtner, W; Aurich, C

    2013-10-01

    Identification of horses by microchip transponder is mandatory within the European Union with only a few exceptions. In this study, the readability of such microchips in 428 horses with three different scanners (A, B and C) and the histological changes at the implantation site in 16 animals were assessed. Identification of microchips differed between scanners (P<0.001), and with 'side of neck' (P<0.001). Scanners A, B and C identified 93.5%, 89.7% and 100% of microchips, respectively, on the 'chip-bearing' side of the neck. From the contralateral side, scanners A, B and C identified 21.5%, 26.9% and 89.5% of transponders, respectively. Microchip readability was affected by age (P<0.001), but not by breed of horse. At necropsy, transponders were found in the subcutaneous fat (n=3), inter- or peri-muscular connective tissue (n=8), or musculature (n=5), where they were surrounded by a fibrous capsule ranging in thickness from 12.7 to 289.5 μm in 15 animals. In two animals, immature granulation tissue with attendant granulomatous inflammation, and a granulomatous myositis, surrounding the microchip were identified, respectively. Severe (n=1), moderate (n=1), and mild (n=3) lymphohistiocytic inflammation was noted within the fibrous capsule. Microchip transponders were found to be a highly reliable and biocompatible method of horse identification. PMID:23769456

  5. Microchip device for liquid phase analysis

    SciTech Connect

    Ramsey, j.m.

    2000-05-01

    The lab-on-a-chip concept has enabled miniature instruments to be developed that allow the rapid execution and automation of fluidic operations such as valving, separation, dilution, mixing, and flow splitting upon the proper application of a motive (driving) force. The integration of these simple operations to perform complete, multiple-step chemical assays is rapidly becoming a reality. Such compact, monolithic devices potentially enjoy advantages in speed, cost, automation, reagent consumption, and waste generation compared to existing laboratory-scale instruments. Initial reports of these microfluidic devices focused on combining various electrokinetically driven separation methods including microchip electrophoresis, gel electrophoresis, micellar electrokinetic chromatography (MEKC) and open channel electrochromatography (OCEC) with fluidic valving to introduce sample plugs into the separation channel. Other operations have quickly been integrated with the separations and fluidic valving on these microchips. For example, integrated devices with mixers/diluters for precolumn and postcolumn analyte derivatization, deoxyribonucleic acid (DNA) restriction digests, enzyme assays, and polymerase chain reaction (PCR) amplification have been added to the basic design. Integrated mixers that can perform solvent programming for both MEKC and OCEC have also been demonstrated. These examples are simple, yet powerful, demonstrations of the potential for lab-on-a-chip devices. In this report, three key areas for improved performance of these devices are described: on-chip calibration techniques, enhanced separative performance, and enhanced detection capabilities.

  6. Chemical modification of polymeric microchip devices.

    PubMed

    Muck, Alexander; Svatos, Ales

    2007-12-15

    Analytical polymeric microchips in both fluidic and array formats offer short analysis times, coupling of many sample processing and chemical reaction steps on one platform with minimal sample and reagent consumption, as well as low cost, minimal fabrication times and disposability. However, the invariable bulk properties of most commercial polymers have driven researchers to develop new modification strategies. This article critically reviews the scope and development of chemical modifications of such polymeric chips since 2003. Surface modifications were based on chemical derivatization or activation of surface layers with reagent solutions, reactive gases and irradiation. Bulk modification of polymer chips used newly incorporation of monomers with selective chemical functionalities throughout the bulk polymer material and integrated the chip modification and fabrication into a single step. Such modifications hold a great promise for establishing a true 'lab-on-chip' as can be seen from many novel applications for modulating electroosmosis, suppressing protein adsorption in microchip capillary electrophoretic separations, extraction of analytes and for zone-specific binding of enzymes and other biomolecules. PMID:18371647

  7. Contactless conductivity detector for microchip capillary electrophoresis

    NASA Technical Reports Server (NTRS)

    Pumera, Martin; Wang, Joseph; Opekar, Frantisek; Jelinek, Ivan; Feldman, Jason; Lowe, Holger; Hardt, Steffen; Svehla, D. (Principal Investigator)

    2002-01-01

    A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate anions. The response was linear (over the 20 microM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 microM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices.

  8. A graphene-modified cellulose paper microchip for HIV detection

    NASA Astrophysics Data System (ADS)

    Safavieh, Mohammadali; Khetani, Sultan; Kaul, Vivasvat; Kuritzkes, Daniel R.; Shafiee, Hadi

    2015-05-01

    Rapid and inexpensive virus detection and quantification at the point-of-care is of paramount importance for HIV management in resource-limited settings. Here, we report on an easy-to-fabricate, cellulose paper-based microchip with printed graphene-modified electrodes for rapid detection of HIV-1 through electrical sensing. We evaluated the effect of electrode material and geometry on the performance of the microchip to detect serially diluted, electrically conductive samples. We evaluated the optimized microchip with HIVspiked samples.

  9. Thin Film Formation and Morphology of Electrosprayed Polydimethylsiloxane.

    PubMed

    Weiss, Florian M; Töpper, Tino; Osmani, Bekim; Deyhle, Hans; Kovacs, Gabor; Müller, Bert

    2016-04-01

    Low-voltage dielectric actuators (DEAs) can be fabricated using submicrometer-thin polydimethylsiloxane (PDMS) films. The two established techniques, namely spin coating and molecular beam deposition, however, are inappropriate to produce multistack DEAs in an efficient way. Therefore, we propose an alternative deposition technique, i.e., the alternating current electrospray deposition (ACESD) of 5 vol % PDMS in ethyl acetate solution and subsequent ultraviolet light curing. Atomic force microscopy makes possible the three-dimensional analysis of cured droplet-like islands. These circular islands, prepared on 2 in. Si(100) wafers from four polymers with molecular masses between 800 and 62 700 g/mol, reveal a characteristic morphology with an increasing height-to-diameter ratio. Using the 6000 g/mol polymer for ACESD, the film morphology evolution was tracked by applying conventional optical microscopy and spectroscopic ellipsometry. When the deposition was terminated after 13 s, circular islands with a mean height of 30 nm were found, while terminating the deposition after about 155 s led to a confluent layer with a mean height of 91 ± 10 nm. Potential electrostatic interactions between the droplets could not be identified through the analysis of spatial island distribution. Nevertheless, ACESD is a budget-priced and competitive deposition technique that can be employed to fabricate submicrometer-thin PDMS films with true nanometer roughness. PMID:26978236

  10. Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates

    NASA Astrophysics Data System (ADS)

    Tang, Jun; Guo, Hao; Zhao, Miaomiao; Yang, Jiangtao; Tsoukalas, Dimitris; Zhang, Binzhen; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2015-11-01

    This paper demonstrates a fabrication technology of Ag wrinkled electrodes with application in highly stretchable wireless sensors. Ag wrinkled thin films that were formed by vacuum deposition on top of pre-strained and relaxed polydimethylsiloxane (PDMS) substrates which have been treated using an O2 plasma and a surface chemical functionalization process can reach a strain limit up to 200%, while surface adhesion area can reach 95%. The electrical characteristics of components such as resistors, inductors and capacitors made from such Ag conductors have remained stable under stretching exhibiting low temperature and humidity coefficients. This technology was then demonstrated for wireless wearable electronics using compatible processing with established micro/nano fabrication technology.

  11. Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates

    PubMed Central

    Tang, Jun; Guo, Hao; Zhao, Miaomiao; Yang, Jiangtao; Tsoukalas, Dimitris; Zhang, Binzhen; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2015-01-01

    This paper demonstrates a fabrication technology of Ag wrinkled electrodes with application in highly stretchable wireless sensors. Ag wrinkled thin films that were formed by vacuum deposition on top of pre-strained and relaxed polydimethylsiloxane (PDMS) substrates which have been treated using an O2 plasma and a surface chemical functionalization process can reach a strain limit up to 200%, while surface adhesion area can reach 95%. The electrical characteristics of components such as resistors, inductors and capacitors made from such Ag conductors have remained stable under stretching exhibiting low temperature and humidity coefficients. This technology was then demonstrated for wireless wearable electronics using compatible processing with established micro/nano fabrication technology. PMID:26585636

  12. Photolithographic surface micromachining of polydimethylsiloxane (PDMS)

    PubMed Central

    Chen, Weiqiang; Lam, Raymond H. W.

    2014-01-01

    A major technical hurdle in microfluidics is the difficulty in achieving high fidelity lithographic patterning on polydimethylsiloxane (PDMS). Here, we report a simple yet highly precise and repeatable PDMS surface micromachining method using direct photolithography followed by reactive ion etching (RIE). Our method to achieve surface patterning of PDMS applied an O2 plasma treatment to PDMS to activate its surface to overcome the challenge of poor photoresist adhesion on PDMS for photolithography. Our photolithographic PDMS surface micromachining technique is compatible with conventional soft lithography techniques and other silicon-based surface and bulk micromachining methods. To illustrate the general application of our method, we demonstrated fabrications of large microfiltration membranes and free-standing beam structures in PDMS. PMID:22089984

  13. Integration of amperometric sensors for microchip capillary electrophoresis application

    NASA Astrophysics Data System (ADS)

    Dicorato, F.; Moore, E.; Glennon, J.

    2011-08-01

    Capillary electrophoresis is a technique for the separation and analysis of chemical compounds. Techniques adopted from the microchip technology knowledge have led to recent developments of electrophoresis system with integration on microchip. Microchip Capillary Electrophoresis (μCE) systems offer a series of advantages as easy integration for Lab-on-a-chip applications, high performance, portability, speed, minimal solvent and sample requirements. A new technological challenge aims at the development of an economic modular microchip capillary electrophoresis systems using separable and independent units concerning the sensor. In this project we worked on the development of an interchangeable amperometric sensor in order to provide a solution to such electrode passivation and facilitating the use of tailored sensors for specific analyte detection besides. Fluidic chips have been machined from cyclic olefin polymer pallets (Zeonor®) using a micro-injection molding machine.

  14. Feline lost: making microchipping compulsory for domestic cats.

    PubMed

    Roberts, M

    2016-08-13

    The independent nature of cats means that they are more likely to become lost or injured than dogs. Maggie Roberts believes that microchipping of cats should be compulsory in the UK as is the case with dogs. PMID:27516564

  15. Apparatus for Precise Indium-Bump Bonding of Microchips

    NASA Technical Reports Server (NTRS)

    Wild, Larry; Mulder, Jerry; Alvarado, Nicholas

    2005-01-01

    An improved apparatus has been designed and built for use in precise positioning and pressing of a microchip onto a substrate (which could, optionally, be another microchip) for the purpose of indium-bump bonding. The apparatus (see figure) includes the following: A stereomicroscope, A stage for precise positioning of the microchip in rotation angle (theta) about the nominally vertical pressing axis and in translation along two nominally horizontal coordinate axes (x and y), and An actuator system that causes a bonding tip to press the microchip against the substrate with a precisely controlled force. In operation, the microscope and the stage are used to position the microchip under the bonding tip and to align the indium bumps on the chip and the substrate, then the actuator system is used to apply a prescribed bonding force for a prescribed time. The improved apparatus supplants a partly similar prior apparatus that operated with less precision and repeatability, producing inconsistent and unreliable bonds. Results of the use of the prior apparatus included broken microchips, uneven bonds, and bonds characterized, variously, by overcompression or undercompression. In that apparatus, the bonding force was generated and controlled by use of a micrometer head positioned over the center of a spring-loaded scale, and the force was applied to the microchip via the scale, which was equipped for digital readout of the force. The inconsistency of results was attributed to the following causes: It was not possible to control the bonding force with sufficient precision or repeatability. Particularly troublesome was the inability to control the force at levels less than the weight of 150 g. Excessive compliance in the spring-loaded scale, combined with deviations from parallelarity of the substrate and bonding-tip surfaces, gave rise to nonuniformity in the pressure applied to the microchip, thereby generating excessive stresses and deformations in the microchip. In the

  16. Fabrication of a Wrinkled Surface on Poly(dimethylsiloxane) Using a Thermal Curing Process

    NASA Astrophysics Data System (ADS)

    Lee, Dong Guk; Jeong, Ok Chan

    2013-06-01

    We describe the fabrication of a spontaneous wrinkled surface on poly(dimethylsiloxane) (PDMS). The wrinkled surface on an elastic PDMS substrate was fabricated by thermally shrinking liquid PDMS coated on a cured PDMS layer during a simple thermal curing process. Optical and atomic force microscopy, deflections of PDMS cantilever beams on the wrinkled surface, and contact angles of water droplets on the wrinkled surface were used to quantitatively investigate the wrinkled patterns on the PDMS layer. The morphology of cells seeded on the fabricated wrinkled surface was observed.

  17. Highly cytocompatible and flexible three-dimensional graphene/polydimethylsiloxane composite for culture and electrochemical detection of L929 fibroblast cells.

    PubMed

    Waiwijit, Uraiwan; Maturos, Thitima; Pakapongpan, Saithip; Phokharatkul, Ditsayut; Wisitsoraat, Anurat; Tuantranont, Adisorn

    2016-08-01

    Recently, three-dimensional graphene interconnected network has attracted great interest as a scaffold structure for tissue engineering due to its high biocompatibility, high electrical conductivity, high specific surface area and high porosity. However, free-standing three-dimensional graphene exhibits poor flexibility and stability due to ease of disintegration during processing. In this work, three-dimensional graphene is composited with polydimethylsiloxane to improve the structural flexibility and stability by a new simple two-step process comprising dip coating of polydimethylsiloxane on chemical vapor deposited graphene/Ni foam and wet etching of nickel foam. Structural characterizations confirmed an interconnected three-dimensional multi-layer graphene structure with thin polydimethylsiloxane scaffold. The composite was employed as a substrate for culture of L929 fibroblast cells and its cytocompatibility was evaluated by cell viability (Alamar blue assay), reactive oxygen species production and vinculin immunofluorescence imaging. The result revealed that cell viability on three-dimensional graphene/polydimethylsiloxane composite increased with increasing culture time and was slightly different from a polystyrene substrate (control). Moreover, cells cultured on three-dimensional graphene/polydimethylsiloxane composite generated less ROS than the control at culture times of 3-6 h. The results of immunofluorescence staining demonstrated that fibroblast cells expressed adhesion protein (vinculin) and adhered well on three-dimensional graphene/polydimethylsiloxane surface. Good cell adhesion could be attributed to suitable surface properties of three-dimensional graphene/polydimethylsiloxane with moderate contact angle and small negative zeta potential in culture solution. The results of electrochemical study by cyclic voltammetry showed that an oxidation current signal with no apparent peak was induced by fibroblast cells and the oxidation current at an

  18. Photopatterning the mechanical properties of polydimethylsiloxane films

    NASA Astrophysics Data System (ADS)

    Cotton, D. P. J.; Popel, A.; Graz, I. M.; Lacour, S. P.

    2011-03-01

    Silicone rubber films with graded and localized mechanical properties are prepared using two-part polydimethylsiloxane (PDMS) elastomer, photoinhibitor compounds and conventional photolithography. First the un-cross-linked PDMS is mixed with benzophenone. The resulting positive photosensitive material is then exposed through a mask to UV light from a conventional mask aligner. Cross-linking of the UV exposed elastomer is inhibited, leading to softer regions than the surrounding unexposed matrix. By empirically fitting the nonlinear, hyperelastic Mooney-Rivlin model to experimentally measured stress-strain curves we determine the equivalent tensile modulus (E) of the rubber film. We show the PDMS tensile modulus can then be adjusted in the 0.65-2.9 MPa range by decreasing the UV exposure dose (from 24 000 to 0 mJ cm-2). Further, using a patterned UV mask, we can locally define differential regions of tensile modulus within a single PDMS rubber film. We demonstrate that "hard islands" (E ≈ 2.9 MPa) of 100 μm minimum diameter can be patterned within a 100-μm-thick, single "soft" PDMS rubber membrane (E ≈ 0.65 MPa) cured at 150 °C for 24 h. Thin gold film conductors patterned directly onto the photopatterned PDMS are stretchable and withstand uniaxial cycling to tens of percent strain. The mechanically "pixellated" PDMS rubber film provides an improved substrate with built-in strain relief for stretchable electronics.

  19. Problems Associated with the Microchip Data of Stray Dogs and Cats Entering RSPCA Queensland Shelters

    PubMed Central

    Lancaster, Emily; Rand, Jacquie; Collecott, Sheila; Paterson, Mandy

    2015-01-01

    Simple Summary Microchip identification has become an important tool to reunite stray dogs and cats with their owners, and is now compulsory in most states of Australia. Improvement of the microchipping system in Australia is limited by a lack of published Australian data documenting the problems experienced by shelter staff when using microchip data to contact the owner of a stray animal. In this study we determine the character and frequency of inaccurate microchip data to identify weaknesses in the current microchipping system. This information could be used to develop strategies that increase the accuracy of microchip data that will increase the reclaiming of stray animals. Abstract A lack of published information documenting problems with the microchip data for the reclaiming of stray animals entering Australian shelters limits improvement of the current microchipping system. A retrospective study analysing admission data for stray, adult dogs (n = 7258) and cats (n = 6950) entering the Royal Society for the Prevention of Cruelty to Animals (RSPCA) Queensland between January 2012 and December 2013 was undertaken to determine the character and frequency of microchip data problems and their impact on outcome for the animal. Only 28% of dogs and 9% of cats were microchipped, and a substantial proportion (37%) had problems with their data, including being registered to a previous owner or organisation (47%), all phone numbers incorrect/disconnected (29%), and the microchip not registered (14%). A higher proportion of owners could be contacted when the microchip had no problems, compared to those with problems (dogs, 93% vs. 70%; cats, 75% vs. 41%). The proportion of animals reclaimed declined significantly between microchipped animals with no data problems, microchipped animals with data problems and non-microchipped animals—87%, 69%, and 37%, respectively, for dogs and 61%, 33%, and 5%, respectively, for cats. Strategies are needed to increase the accuracy of

  20. Sterilization of polydimethylsiloxane surface with Chinese herb extract: a new antibiotic mechanism of chlorogenic acid.

    PubMed

    Ren, Song; Wu, Ming; Guo, Jiayu; Zhang, Wang; Liu, Xiaohan; Sun, Lili; Holyst, Robert; Hou, Sen; Fang, Yongchun; Feng, Xizeng

    2015-01-01

    Coating of polydimethylsiloxane (PDMS) surface with a traditional Chinese herb extract chlorogenic acid (CA) solves the contemporary problem of sterilization of PDMS surface. The E. coli grows slower and has a higher death rate on the CA-coated PDMS surfaces. A smoother morphology of these E. coli cell wall is observed by atomic force microscopy (AFM). Unlike the reported mechanism, where CA inhibits bacterial growth by damaging the cell membrane in the bulk solution, we find the CA-coated PDMS surface also decreases the stiffness of the cell wall. A decrease in the Young's modulus of the cell wall from 3 to 0.8 MPa is reported. Unexpectedly, the CA effect on the swarming ability and the biofilm stability of the bacteria can be still observed, even after they have been removed from the CA environment, indicating a decrease in their resistance to antibiotics for a prolonged time. The CA-coated PDMS surface shows better antibiotic effect against three types of both Gram-positive and Gran-negative bacteria than the gentamicin-coated PDMS surface. Coating of CA on PDMS surface not only solves the problem of sterilization of PDMS surface, but also shines light on the application of Chinese traditional herbs in scientific research. PMID:25993914

  1. Sterilization of polydimethylsiloxane surface with Chinese herb extract: a new antibiotic mechanism of chlorogenic acid

    PubMed Central

    Ren, Song; Wu, Ming; Guo, Jiayu; Zhang, Wang; Liu, Xiaohan; Sun, Lili; Holyst, Robert; Hou, Sen; Fang, Yongchun; Feng, Xizeng

    2015-01-01

    Coating of polydimethylsiloxane (PDMS) surface with a traditional Chinese herb extract chlorogenic acid (CA) solves the contemporary problem of sterilization of PDMS surface. The E. coli grows slower and has a higher death rate on the CA-coated PDMS surfaces. A smoother morphology of these E. coli cell wall is observed by atomic force microscopy (AFM). Unlike the reported mechanism, where CA inhibits bacterial growth by damaging the cell membrane in the bulk solution, we find the CA-coated PDMS surface also decreases the stiffness of the cell wall. A decrease in the Young’s modulus of the cell wall from 3 to 0.8 MPa is reported. Unexpectedly, the CA effect on the swarming ability and the biofilm stability of the bacteria can be still observed, even after they have been removed from the CA environment, indicating a decrease in their resistance to antibiotics for a prolonged time. The CA-coated PDMS surface shows better antibiotic effect against three types of both Gram-positive and Gran-negative bacteria than the gentamicin-coated PDMS surface. Coating of CA on PDMS surface not only solves the problem of sterilization of PDMS surface, but also shines light on the application of Chinese traditional herbs in scientific research. PMID:25993914

  2. Bioinspired polydimethylsiloxane-based composites with high shear resistance against wet tissue.

    PubMed

    Fischer, Sarah C L; Levy, Oren; Kroner, Elmar; Hensel, René; Karp, Jeffrey M; Arzt, Eduard

    2016-08-01

    Patterned microstructures represent a potential approach for improving current wound closure strategies. Microstructures can be fabricated by multiple techniques including replica molding of soft polymer-based materials. However, polymeric microstructures often lack the required shear resistance with tissue needed for wound closure. In this work, scalable microstructures made from composites based on polydimethylsiloxane (PDMS) were explored to enhance the shear resistance with wet tissue. To achieve suitable mechanical properties, PDMS was reinforced by incorporation of polyethylene (PE) particles into the pre-polymer and by coating PE particle reinforced substrates with parylene. The reinforced microstructures showed a 6-fold enhancement, the coated structures even a 13-fold enhancement in Young׳s modulus over pure PDMS. Shear tests of mushroom-shaped microstructures (diameter 450µm, length 1mm) against chicken muscle tissue demonstrate first correlations that will be useful for future design of wound closure or stabilization implants. PMID:26849031

  3. Oligonucleotide microchip for subtyping of influenza A virus

    PubMed Central

    Fesenko, Eugeny E.; Kireyev, Dmitry E.; Gryadunov, Dmitry A.; Mikhailovich, Vladimir M.; Grebennikova, Tatyana V.; L’vov, Dmitry K.; Zasedatelev, Alexander S.

    2007-01-01

    Background  Influenza A viruses are classified into subtypes depending on the antigenic properties of their two outer glycoproteins, hemagglutinin (HA) and neuraminidase (NA). Sixteen subtypes of HA and nine of NA are known. Lately, the circulation of some subtypes (H7N7, H5N1) has been closely watched because of the epidemiological threat they present. Objectives  This study assesses the potential of using gel‐based microchip technology for fast and sensitive molecular subtyping of the influenza A virus. Methods  The method employs a microchip of 3D gel‐based elements containing immobilized probes. Segments of the HA and NA genes are amplified using multiplex RT‐PCR and then hybridized with the microchip. Results  The developed microchip was validated using a panel of 21 known reference strains of influenza virus. Selected strains represented different HA and NA subtypes derived from avian, swine and human hosts. The whole procedure takes 10 hours and enables one to identify 15 subtypes of HA and two subtypes of NA. Forty‐one clinical samples isolated during the poultry fall in Novosibirsk (Russia, 2005) were successfully identified using the proposed technique. The sensitivity and specificity of the method were 76% and 100%, respectively, compared with the ‘gold standard’ techniques (virus isolation with following characterization by immunoassay). Conclusions  We conclude that the method of subtyping using gel‐based microchips is a promising approach for fast detection and identification of influenza A, which may greatly improve its monitoring. PMID:19453417

  4. Electroactive intercalators for DNA analysis on microchip electrophoresis.

    PubMed

    Castaño-Alvarez, Mario; Fernández-Abedul, M Teresa; Costa-García, Agustín

    2007-12-01

    Miniaturized analytical systems, especially microchip CE (MCE), are becoming a promising tool for analytical purposes including DNA analysis. These microdevices require a sensitive and miniaturizable detection system such as electrochemical detection (ED). Several electroactive DNA intercalators, including the organic dye methylene blue (MB), anthraquinone derivatives, and the metal complexes Fe(phen)3 2+ and Ru(phen)3 2+, have been tested for using in combination with thermoplastic olefin polymer of amorphous structure (Topas) CE-microchips and ED. Two end-channel approaches for integration of gold wire electrodes in CE-ED microchip were used. A 250 microm diameter gold wire was manually aligned at the outlet of the separation channel. A new approach based on a guide channel for integration of 100 and 50 microm diameter gold wire has been also developed in order to reduce the background current and the baseline noise level. Modification of gold wire electrodes has been also tested to improve the detector performance. Application of MCE-ED for ssDNA detection has been studied and demonstrated for the first time using the electroactive dye MB. Electrostatic interaction between cationic MB and anionic ssDNA was used for monitoring the DNA on microchips. Thus, reproducible calibration curves for ssDNA were obtained. This study advances the feasibility of direct DNA analysis using CE-microchip with ED. PMID:18004710

  5. A microchip platform for structural oncology applications

    PubMed Central

    Winton, Carly E; Gilmore, Brian L; Demmert, Andrew C; Karageorge, Vasilea; Sheng, Zhi; Kelly, Deborah F

    2016-01-01

    Recent advances in the development of functional materials offer new tools to dissect human health and disease mechanisms. The use of tunable surfaces is especially appealing as substrates can be tailored to fit applications involving specific cell types or tissues. Here we use tunable materials to facilitate the three-dimensional (3D) analysis of BRCA1 gene regulatory complexes derived from human cancer cells. We employed a recently developed microchip platform to isolate BRCA1 protein assemblies natively formed in breast cancer cells with and without BRCA1 mutations. The captured assemblies proved amenable to cryo-electron microscopy (EM) imaging and downstream computational analysis. Resulting 3D structures reveal the manner in which wild-type BRCA1 engages the RNA polymerase II (RNAP II) core complex that contained K63-linked ubiquitin moieties—a putative signal for DNA repair. Importantly, we also determined that molecular assemblies harboring the BRCA15382insC mutation exhibited altered protein interactions and ubiquitination patterns compared to wild-type complexes. Overall, our analyses proved optimal for developing new structural oncology applications involving patient-derived cancer cells, while expanding our knowledge of BRCA1’s role in gene regulatory events. PMID:27583302

  6. Rapid bonding of Pyrex glass microchips.

    PubMed

    Akiyama, Yoshitake; Morishima, Keisuke; Kogi, Atsuna; Kikutani, Yoshikuni; Tokeshi, Manabu; Kitamori, Takehiko

    2007-03-01

    A newly developed vacuum hot press system has been specially designed for the thermal bonding of glass substrates in the fabrication process of Pyrex glass microchemical chips. This system includes a vacuum chamber equipped with a high-pressure piston cylinder and carbon plate heaters. A temperature of up to 900 degrees C and a force of as much as 9800 N could be applied to the substrates in a vacuum atmosphere. The Pyrex substrates bonded with this system under different temperatures, pressures, and heating times were evaluated by tensile strength tests, by measurements of thickness, and by observations of the cross-sectional shapes of the microchannels. The optimal bonding conditions of the Pyrex glass substrates were 570 degrees C for 10 min under 4.7 N/mm(2) of applied pressure. Whereas more than 16 h is required for thermal bonding with a conventional furnace, the new system could complete the whole bonding processes within just 79 min, including heating and cooling periods. Such improvements should considerably enhance the production rate of Pyrex glass microchemical chips. Whereas flat and dust-free surfaces are required for conventional thermal bonding, especially without long and repeated heating periods, our hot press system could press a fine dust into glass substrates so that even the areas around the dust were bonded. Using this capability, we were able to successfully integrate Pt/Ti thin film electrodes into a Pyrex glass microchip. PMID:17370301

  7. Analysis of Anions in Ambient Aerosols by Microchip Capillary Electrophoresis

    SciTech Connect

    Liu, Yan; MacDonald, David A.; Yu, Xiao-Ying; Hering, Susanne V.; Collett, Jeffrey L.; Henry, Charles S.

    2006-10-01

    We describe a microchip capillary electrophoresis method for the analysis of nitrate and sulfate in ambient aerosols. Investigating the chemical composition of ambient aerosol particles is essential for understanding their sources and effects. Significant progress has been made towards developing mass spectrometry-based instrumentation for rapid qualitative analysis of aerosols. Alternative methods for rapid quantification of selected high abundance compounds are needed to augment the capacity for widespread routine analysis. Such methods could provide much higher temporal and spatial resolution than can be achieved currently. Inorganic anions comprise a large percentage of particulate mass with nitrate and sulfate among the most abundant species. While ion chromatography has proven very useful for analyzing extracts of time-integrated ambient aerosol samples collected on filters and for semi-continuous, on-line particle composition measurements, there is a growing need for development of new compact, inexpensive approaches to routine on-line aerosol ion analysis for deployment in spatially dense, atmospheric measurement networks. Microchip capillary electrophoresis provides the necessary speed and portability to address this need. In this report, on-column contact conductivity detection is used with hydrodynamic injection to create a simple microchip instrument for analysis of nitrate and sulfate. On-column contact conductivity detection was achieved using a Pd decoupler placed upstream from the working electrodes. Microchips containing two Au or Pd working electrodes showed a good linear range (5-500 µM) and low limits-of-detection for sulfate and nitrate with Au providing the lowest detection limits (1 µM) for both ions. The completed microchip system was used to analyze ambient aerosol filter samples. Nitrate and sulfate concentrations measured by the microchip matched the concentrations measured by ion chromatography.

  8. Thickness dependence of ice removal stress for a polydimethylsiloxane nanocomposite: Sylgard 184.

    PubMed

    Wang, Chenyu; Fuller, Trae; Zhang, Wei; Wynne, Kenneth J

    2014-11-01

    Minimizing adhesion of ice has been the subject of extensive studies because of importance to applications such aircraft wings, spacecraft, and power transmission wires. A growing interest concerns coatings for wind turbine blades and refrigeration. Herein, a new laboratory test was employed to obtain the thickness dependence of ice adhesion for Sylgard 184-a filled polydimethylsiloxane elastomer. A correlation between ice adhesion and coating thickness (t) was found that follows a relationship developed by Kendall over 40 years ago for removal of a rigid object from an elastomer. With a 0.05 mm/s probe speed a nearly linear relationship between peak removal stress (Ps) and 1/t(1/2) was obtained with Ps ∼ 460 kPa for an 18 μm coating, decreasing to ∼120 kPa for 533 μm. Preliminary results suggest that below ∼10 μm Ps departs from the 1/t(1/2) correlation while above ∼500 μm a limiting value for Ps may be reached. We previously reported that probe speed has negligible effect on the glassy polymer PMMA. In contrast, probe speed is identified as an important variable for testing ice release on elastomeric Sylgard 184 coatings. While work of adhesion, which is related to surface free energy, is recognized as an important factor that can affect ice release, the results reported herein show that coating thickness can override this single parameter for elastomeric substrates. PMID:25299447

  9. MicroChip Imager Module for Recognition of Microorganisms

    Energy Science and Technology Software Center (ESTSC)

    2001-01-01

    The MicroChip Reader for Cereus Group takes the table of intensities of hybridization signals produced by the MicroChip Imager software and evokes a series of steps designed to recognize the pattern of intensities specific to a particular Cereus subgroup. Seven subgroups of the Cereus group can be identified by particular features of their RNA sequence. The Reader also provides statistics documenting how well its conclusion is confirmed by the hybridization signals. At the user’s request,more » the Reader can list every recognition step utilized so that the user can verify the recognition process manually if desired.« less

  10. MicroChip Imager Module for Recognition of Microorganisms

    SciTech Connect

    Alferov, Oleg

    2001-01-01

    The MicroChip Reader for Cereus Group takes the table of intensities of hybridization signals produced by the MicroChip Imager software and evokes a series of steps designed to recognize the pattern of intensities specific to a particular Cereus subgroup. Seven subgroups of the Cereus group can be identified by particular features of their RNA sequence. The Reader also provides statistics documenting how well its conclusion is confirmed by the hybridization signals. At the user’s request, the Reader can list every recognition step utilized so that the user can verify the recognition process manually if desired.

  11. Adding functionality to microchips by wafer post-processing

    NASA Astrophysics Data System (ADS)

    Schmitz, Jurriaan

    2007-06-01

    The traditional microchip processes, stores and communicates electrical information. Here we review an emerging class of microchips that have additional functionality through extra integrated components in the chip. In the final manufacturing stage, layers are added on top of the chip, with a specific property such as sensitivity to ionizing radiation. This paper reviews the technology underlying these monolithic microsystems, including the incorporation of new materials, the unconventional application of photoresist layers, and low-temperature technology for suspended membranes. The manufacturing of exemplary microsystems, such as the active pixel sensor and liquid-crystal-on-silicon, is detailed. A new class of fully integrated radiation imaging systems is now technologically within reach.

  12. Capillary and microchip electrophoretic analysis of polycyclic aromatic hydrocarbons.

    PubMed

    Ferey, Ludivine; Delaunay, Nathalie

    2015-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants which can reach the environment and food in different ways. Because of their high toxicity, two international regulatory institutions, the US Environmental Protection Agency and the European Food Safety Authority, have classified PAHs as priority pollutants, generating an important demand for the detection and identification of PAHs. Thus, sensitive, fast, and cheap methods for the analysis of PAHs in environmental and food samples are urgently needed. Within this context, electrophoresis, in capillary or microchip format, displays attractive features. This review presents and critically discusses the published literature on the different approaches to capillary and microchip electrophoresis analysis of PAHs. PMID:25542576

  13. Multiplexed Western Blotting Using Microchip Electrophoresis.

    PubMed

    Jin, Shi; Furtaw, Michael D; Chen, Huaxian; Lamb, Don T; Ferguson, Stephen A; Arvin, Natalie E; Dawod, Mohamed; Kennedy, Robert T

    2016-07-01

    Western blotting is a commonly used protein assay that combines the selectivity of electrophoretic separation and immunoassay. The technique is limited by long time, manual operation with mediocre reproducibility, and large sample consumption, typically 10-20 μg per assay. Western blots are also usually used to measure only one protein per assay with an additional housekeeping protein for normalization. Measurement of multiple proteins is possible; however, it requires stripping membranes of antibody and then reprobing with a second antibody. Miniaturized alternatives to Western blot based on microfluidic or capillary electrophoresis have been developed that enable higher-throughput, automation, and greater mass sensitivity. In one approach, proteins are separated by electrophoresis on a microchip that is dragged along a polyvinylidene fluoride membrane so that as proteins exit the chip they are captured on the membrane for immunoassay. In this work, we improve this method to allow multiplexed protein detection. Multiple injections made from the same sample can be deposited in separate tracks so that each is probed with a different antibody. To further enhance multiplexing capability, the electrophoresis channel dimensions were optimized for resolution while keeping separation and blotting times to less than 8 min. Using a 15 μm deep × 50 μm wide × 8.6 cm long channel, it is possible to achieve baseline resolution of proteins that differ by 5% in molecular weight, e.g., ERK1 (44 kDa) from ERK2 (42 kDa). This resolution allows similar proteins detected by cross-reactive antibodies in a single track. We demonstrate detection of 11 proteins from 9 injections from a single Jurkat cell lysate sample consisting of 400 ng of total protein using this procedure. Thus, multiplexed Western blots are possible without cumbersome stripping and reprobing steps. PMID:27270033

  14. Direct detection of cancer biomarkers in blood using a “place n play” modular polydimethylsiloxane pump

    PubMed Central

    Zhang, Honglian; Li, Gang; Liao, Lingying; Mao, HongJu; Jin, Qinghui; Zhao, Jianlong

    2013-01-01

    Cancer biomarkers have significant potential as reliable tools for the early detection of the disease and for monitoring its recurrence. However, most current methods for biomarker detection have technical difficulties (such as sample preparation and specific detector requirements) which limit their application in point of care diagnostics. We developed an extremely simple, power-free microfluidic system for direct detection of cancer biomarkers in microliter volumes of whole blood. CEA and CYFRA21-1 were chosen as model cancer biomarkers. The system automatically extracted blood plasma from less than 3 μl of whole blood and performed a multiplex sample-to-answer assay (nano-ELISA (enzyme-linked immunosorbent assay) technique) without the use of external power or extra components. By taking advantage of the nano-ELISA technique, this microfluidic system detected CEA at a concentration of 50 pg/ml and CYFRA21-1 at a concentration of 60 pg/ml within 60 min. The combination of PnP polydimethylsiloxane (PDMS) pump and nano-ELISA technique in a single microchip system shows great promise for the detection of cancer biomarkers in a drop of blood. PMID:24404025

  15. A Facile Method of Preparing Transparent Superhydrophobic Film Based on Ethyl alpha-Cyanoacrylate and Polydimethylsiloxane.

    PubMed

    Zhuang, Aoyun; Yang, Lijun; Liao, Ruijin; Guo, Chao; Zuo, Zhiping; Yuan, Yuan

    2016-02-01

    Fabrication of robust and transparent superhydrophobic thin film with high transmittance in the visible light region by coating mixing solution included by ethyl alpha-cyanoacrylate and polydimethylsiloxane (PDMS) on the acid-etched Al foil has been developed. The micro/nano-structured protrusions of the film surface were composed mainly of ethyl alpha-cyanoacrylate which was more likely to flow into the pits on acid-etched Al foil compared to polydimethylsiloxane while the main body of the film was constituted by the PDMS since its excellent transparency and mechanical flexibility. Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscope (AFM), X-ray Photo- electron Spectroscopy (XPS), X-ray diffraction (XRD) and Drop Meter were utilized to evaluate its morphology, accurate topography and quantitative roughness, element types and levels, crystallinity and wettability respectively. Optical properties of the as-prepared films were analyzed by UV-VIS scanning spectrophotometer. The result showed that the contact angle of the film was greater than 155 degrees and the transmittance of the film was greater than 90% simultaneously. In addition, the film showed good surface mechanical stability and acid-alkali resistance which has great potential in durable application of various fields. PMID:27433615

  16. Implantable microchip: the futuristic controlled drug delivery system.

    PubMed

    Sutradhar, Kumar Bishwajit; Sumi, Chandra Datta

    2016-01-01

    There is no doubt that controlled and pulsatile drug delivery system is an important challenge in medicine over the conventional drug delivery system in case of therapeutic efficacy. However, the conventional drug delivery systems often offer a limited by their inability to drug delivery which consists of systemic toxicity, narrow therapeutic window, complex dosing schedule for long term treatment etc. Therefore, there has been a search for the drug delivery system that exhibit broad enhancing activity for more drugs with less complication. More recently, some elegant study has noted that, a new type of micro-electrochemical system or MEMS-based drug delivery systems called microchip has been improved to overcome the problems related to conventional drug delivery. Moreover, micro-fabrication technology has enabled to develop the implantable controlled released microchip devices with improved drug administration and patient compliance. In this article, we have presented an overview of the investigations on the feasibility and application of microchip as an advanced drug delivery system. Commercial manufacturing materials and methods, related other research works and current advancement of the microchips for controlled drug delivery have also been summarized. PMID:24758139

  17. Microchip-based Devices for Molecular Diagnosis of Genetic Diseases.

    PubMed

    Cheng; Fortina; Surrey; Kricka; Wilding

    1996-09-01

    Microchips, constructed with a variety of microfabrication technologies (photolithography, micropatterning, microjet printing, light-directed chemical synthesis, laser stereochemical etching, and microcontact printing) are being applied to molecular biology. The new microchip-based analytical devices promise to solve the analytical problems faced by many molecular biologists (eg, contamination, low throughput, and high cost). They may revolutionize molecular biology and its application in clinical medicine, forensic science, and environmental monitoring. A typical biochemical analysis involves three main steps: (1) sample preparation, (2) biochemical reaction, and (3) detection (either separation or hybridization may be involved) accompanied by data acquisition and interpretation. The construction of a miniturized analyzer will therefore necessarily entail the miniaturization and integration of all three of these processes. The literature related to the miniaturization of these three processes indicates that the greatest emphasis so far is on the investigation and development of methods for the detection of nucleic acid, followed by the optimization of a biochemical reaction, such as the polymerase chain reaction. The first step involving sample preparation has received little attention. In this review the state of the art of, microchip-based, miniaturized analytical processes (eg, sample preparation, biochemical reaction, and detection of products) are outlined and the applications of microchip-based devices in the molecular diagnosis of genetic diseases are discussed. PMID:10462559

  18. Biotoxin sensing in food and environment via microchip.

    PubMed

    Zhang, Zhaowei; Yu, Li; Xu, Lin; Hu, Xiaofeng; Li, Peiwu; Zhang, Qi; Ding, Xiaoxia; Feng, Xiaojun

    2014-06-01

    Biotoxin contamination in food and environmental samples has threatened health or life of human and animals. Thus, a rapid lab-independent sensing method for biotoxin determination is urgently required. Microchip sensing system allows a promising rapid and low-cost detection strategy. Herein, the recent development of various microchips, including microfluidic chip and microarray, has been discussed to sense various biotoxins in food and environmental samples (i.e. phytotoxin, animal toxin, marine toxin, and mycotoxin). Microchip can be served as both analyte transportation and sensing platform, via either labeling or labeling-free sensing strategy. Because of its fast sensing time, low sample consumption, ready portability, and high compatibility, it has been extensively employed in biotoxin determination in both academic and industrial circle. With the advances of fabrication strategies and sensing modes, the microchip performance has been dramatically improved, including sensitivity, efficiency, reliability, stability, cost saving, portability. The potential applications can be found wide spread in biotoxin sensing in the near future, while their practical application in real sample need to be addressed. PMID:24723235

  19. A micro surface tension alveolus (MISTA) in a glass microchip.

    PubMed

    Peng, Xing Yue Larry; Wu, Lan-Qin; Zhang, Na; Hu, Li-Dan; Li, You; Li, Wen-Juan; Li, Dong-Hui; Huang, Ping; Zhou, Yong-Liang

    2009-11-21

    We have designed a non-membrane micro surface tension alveolus (MISTA) in a glass microchip for direct gas exchange and micro gradient control. Hemoglobin (Hb) in the liquid phase indicates the rapid gas gradient changes of O2 and CO2 shifted by the difference in pressure between the liquid and the gas. PMID:19865732

  20. Longevity of radiofrequency identification device microchips in citrus trees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term identification of individual plants in the field is an important part of many types of botanical and horticultural research. In a previous report, we described methods for using implanted radiofrequency (RFID) microchips to tag citrus trees for field research. This report provides an upd...

  1. Apparatus and method for performing electrodynamic focusing on a microchip

    DOEpatents

    Ramsey, John Michael; Jacobson, Stephen C.

    1999-01-01

    A microchip device includes a focusing channel, in which an electric field strength established in the focusing channel is controlled relative to an electric field strength established in a material transport channel segment to spatially focus the material traversing the material transport channel segment.

  2. Apparatus and method for performing electrodynamic focusing on a microchip

    DOEpatents

    Ramsey, J.M.; Jacobson, S.C.

    1999-01-12

    A microchip device includes a focusing channel, in which an electric field strength established in the focusing channel is controlled relative to an electric field strength established in a material transport channel segment to spatially focus the material traversing the material transport channel segment. 22 figs.

  3. Integrated Micro-Chip Amino Acid Chirality Detector for MOD

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Bada, J. L.; Botta, O.; Kminek, G.; Grunthaner, F.; Mathies, R.

    2001-01-01

    Integration of a micro-chip capillary electrophoresis analyzer with a sublimation-based extraction technique, as used in the Mars Organic Detector (MOD), for the in-situ detection of amino acids and their enantiomers on solar system bodies. Additional information is contained in the original extended abstract.

  4. Silicone nanocomposite coatings for fabrics

    NASA Technical Reports Server (NTRS)

    Eberts, Kenneth (Inventor); Lee, Stein S. (Inventor); Singhal, Amit (Inventor); Ou, Runqing (Inventor)

    2011-01-01

    A silicone based coating for fabrics utilizing dual nanocomposite fillers providing enhanced mechanical and thermal properties to the silicone base. The first filler includes nanoclusters of polydimethylsiloxane (PDMS) and a metal oxide and a second filler of exfoliated clay nanoparticles. The coating is particularly suitable for inflatable fabrics used in several space, military, and consumer applications, including airbags, parachutes, rafts, boat sails, and inflatable shelters.

  5. Synthesis of Macroporous Poly(dimethylsiloxane) Scaffolds for Tissue Engineering Applications

    PubMed Central

    Pedraza, Eileen; Brady, Ann-Christina; Fraker, Christopher A.

    2015-01-01

    Macroporous, biostable scaffolds with controlled porous architecture were prepared from poly(dimethylsiloxane) (PDMS) using sodium chloride particles (NaCl) and a solvent casting and particulate leaching (SCPL) technique. The effect of particulate size range and overall porosity on the resulting structure was evaluated. Results found 90% v/v scaffolds and particulate ranges above 100 µm to have the most optimal open framework and porosity. Resulting hydrophobic PDMS scaffolds were coated with fibronectin and evaluated as a platform for adherent cell culture using human mesenchymal stem cells. Biocompatibility of PDMS scaffolds was also evaluated in a rodent model, where implants were found to be highly biocompatibile and biostable, with positive extracellular matrix deposition throughout the scaffold. These results demonstrate the suitability of macroporous PDMS scaffolds for tissue engineering applications where strong integration with the host is desired. PMID:23683037

  6. Simple surface engineering of polydimethylsiloxane with polydopamine for stabilized mesenchymal stem cell adhesion and multipotency

    PubMed Central

    Chuah, Yon Jin; Koh, Yi Ting; Lim, Kaiyang; Menon, Nishanth V.; Wu, Yingnan; Kang, Yuejun

    2015-01-01

    Polydimethylsiloxane (PDMS) has been extensively exploited to study stem cell physiology in the field of mechanobiology and microfluidic chips due to their transparency, low cost and ease of fabrication. However, its intrinsic high hydrophobicity renders a surface incompatible for prolonged cell adhesion and proliferation. Plasma-treated or protein-coated PDMS shows some improvement but these strategies are often short-lived with either cell aggregates formation or cell sheet dissociation. Recently, chemical functionalization of PDMS surfaces has proved to be able to stabilize long-term culture but the chemicals and procedures involved are not user- and eco-friendly. Herein, we aim to tailor greener and biocompatible PDMS surfaces by developing a one-step bio-inspired polydopamine coating strategy to stabilize long-term bone marrow stromal cell culture on PDMS substrates. Characterization of the polydopamine-coated PDMS surfaces has revealed changes in surface wettability and presence of hydroxyl and secondary amines as compared to uncoated surfaces. These changes in PDMS surface profile contribute to the stability in BMSCs adhesion, proliferation and multipotency. This simple methodology can significantly enhance the biocompatibility of PDMS-based microfluidic devices for long-term cell analysis or mechanobiological studies. PMID:26647719

  7. Simple surface engineering of polydimethylsiloxane with polydopamine for stabilized mesenchymal stem cell adhesion and multipotency.

    PubMed

    Chuah, Yon Jin; Koh, Yi Ting; Lim, Kaiyang; Menon, Nishanth V; Wu, Yingnan; Kang, Yuejun

    2015-01-01

    Polydimethylsiloxane (PDMS) has been extensively exploited to study stem cell physiology in the field of mechanobiology and microfluidic chips due to their transparency, low cost and ease of fabrication. However, its intrinsic high hydrophobicity renders a surface incompatible for prolonged cell adhesion and proliferation. Plasma-treated or protein-coated PDMS shows some improvement but these strategies are often short-lived with either cell aggregates formation or cell sheet dissociation. Recently, chemical functionalization of PDMS surfaces has proved to be able to stabilize long-term culture but the chemicals and procedures involved are not user- and eco-friendly. Herein, we aim to tailor greener and biocompatible PDMS surfaces by developing a one-step bio-inspired polydopamine coating strategy to stabilize long-term bone marrow stromal cell culture on PDMS substrates. Characterization of the polydopamine-coated PDMS surfaces has revealed changes in surface wettability and presence of hydroxyl and secondary amines as compared to uncoated surfaces. These changes in PDMS surface profile contribute to the stability in BMSCs adhesion, proliferation and multipotency. This simple methodology can significantly enhance the biocompatibility of PDMS-based microfluidic devices for long-term cell analysis or mechanobiological studies. PMID:26647719

  8. Comprehensive evaluation of haemostatic function in von Willebrand disease patients using a microchip-based flow chamber system.

    PubMed

    Ogiwara, K; Nogami, K; Hosokawa, K; Ohnishi, T; Matsumoto, T; Shima, M

    2015-01-01

    The diagnosis of von Willebrand disease (VWD) is difficult due to the wide spectrum of clinical phenotypes associated with this disorder. We have analysed and characterized haemostatic function in VWD patients using a microchip-based flow chamber system. Microchips coated with either collagen [platelet (PL)-chip] or collagen/thromboplastin [atherome (AR)-chip] were used to evaluate platelet thrombus formation at 1000 s(-1) and fibrin-rich platelet thrombus formation at 240 s(-1) respectively. Blood samples from an asymptomatic patient with VWD type 1 [von Willebrand factor (VWF): RCo 3.2%; bleeding score (BS 2] displayed normal thrombus formation in both PL- and AR-chips, whereas blood from a symptomatic type 1 patient (VWF: RCo 14%, BS 9) had significantly delayed capillary occlusion. Nearly complete suppression of the flow pressure increase was observed in symptomatic patients with VWD type 2A (BS 13) and 2N (BS 27), whereas no flow pressure was found for the type 3 patient (BS 6). Fibrin-rich platelet thrombus formation was only weakly increased by the in vitro addition of factor VIII (FVIII) to blood samples from the type 3 patient, but was normalized by the addition of VWF/FVIII. The in vivo effects of treatment with desmopressin or VWF/FVIII for the symptomatic patients were analysed using two types of microchips. The PL-chip was highly sensitive for patients' VWF-mediated platelet functions, whereas the AR-chip allowed assessment of overall haemostatic ability, including sensitivity to both VWF and FVIII. The combined analysis with PL- and AR-chips may be potentially useful for the diagnosis of VWD based on clinical phenotypes, and for monitoring drug effects. PMID:25545301

  9. Customized oligonucleotide microchips that convert multiple genetic information to simple patterns, are portable and reusable

    DOEpatents

    Mirzabekov, Andrei; Guschin, Dmitry Y.; Chik, Valentine; Drobyshev, Aleksei; Fotin, Alexander; Yershov, Gennadiy; Lysov, Yuri

    2002-01-01

    This invention relates to using customized oligonucleotide microchips as biosensors for the detection and identification of nucleic acids specific for different genes, organisms and/or individuals in the environment, in food and in biological samples. The microchips are designed to convert multiple bits of genetic information into simpler patterns of signals that are interpreted as a unit. Because of an improved method of hybridizing oligonucleotides from samples to microchips, microchips are reusable and transportable. For field study, portable laser or bar code scanners are suitable.

  10. Vapor deposition of cross-linked fluoropolymer barrier coatings onto pre-assembled microfluidic devices.

    PubMed

    Riche, Carson T; Marin, Brandon C; Malmstadt, Noah; Gupta, Malancha

    2011-09-21

    The interior surfaces of pre-assembled poly(dimethylsiloxane) (PDMS) microfluidic devices were modified with a cross-linked fluoropolymer barrier coating that significantly increased the chemical compatibility of the devices. PMID:21850298

  11. Radially polarized cylindrical vector beams from a monolithic microchip laser

    NASA Astrophysics Data System (ADS)

    Naidoo, Darryl; Fromager, Michael; Ait-Ameur, Kamel; Forbes, Andrew

    2015-11-01

    Monolithic microchip lasers consist of a thin slice of laser crystal where the cavity mirrors are deposited directly onto the end faces. While this property makes such lasers very compact and robust, it prohibits the use of intracavity laser beam shaping techniques to produce complex light fields. We overcome this limitation and demonstrate the selection of complex light fields in the form of vector-vortex beams directly from a monolithic microchip laser. We employ pump reshaping and a thermal gradient across the crystal surface to control both the intensity and polarization profile of the output mode. In particular, we show laser oscillation on a superposition of Laguerre-Gaussian modes of zero radial and nonzero azimuthal index in both the scalar and vector regimes. Such complex light fields created directly from the source could find applications in fiber injection, materials processing and in simulating quantum processes.

  12. Microchip-based detection of magnetically labeled cancer biomarkers☆

    PubMed Central

    Muluneh, Melaku; Issadore, David

    2015-01-01

    Micro-magnetic sensing and actuation have emerged as powerful tools for the diagnosis and monitoring of cancer. These technologies can be miniaturized and integrated onto compact, microfluidic platforms, enabling molecular diagnostics to be performed in practical clinical settings. Molecular targets tagged with magnetic nanoparticles can be detected with high sensitivity directly in unprocessed clinical samples (e.g. blood, sputum) due to the inherently negligible magnetic susceptibility of biological material. As a result, magnetic microchip-based diagnostics have been applied with great success to the isolation and detection of rare cells and the measurement of sparse soluble proteins. In this paper, we review recent advances in microchip-based detection of magnetically labeled biomarkers and their translation to clinical applications in cancer. PMID:24099664

  13. 1.6 μm microchip laser

    NASA Astrophysics Data System (ADS)

    Šulc, J.; Jelínková, H.; Ryba-Romanowski, W.; Lukasiewicz, T.

    2009-03-01

    Properties of new pulsed-diode-pumped Er:YVO4 and Er:YVO4+CaO microchip lasers working in an ``eye-safe'' spectral region were investigated. As a pumping source, a fiber coupled (core diameter-200 μm) laser diode emitting radiation at wavelength 976 nm was used. The laser diode was operating in pulsed regime with 3 ms pulse width, and 20 Hz repetition rate. The result obtained was 175 mW and 152 mW output peak power for the Er:YVO4 and Er:YVO4+CaO lasers, respectively. The maximal efficiency with respect to the absorbed power was ~ 5%. The laser emission for Er:YVO4 microchip was observed in detail in the range 1593 nm to 1604 nm with respect to pumping. However, for Er:YVO4+CaO crystal only 1604 nm was generated.

  14. Variability of microchip capillary electrophoresis with conductivity detection.

    PubMed

    Tantra, Ratna; Robinson, Kenneth; Sikora, Aneta

    2014-02-01

    Microfluidic CE with conductivity detection platforms could have an impact on the future development of smaller, faster and portable devices. However, for the purpose of reliable identification and quantification, there is a need to understand the degree of irreproducibility associated with the analytical technique. In this study, a protocol was developed to remove baseline drift problems sometimes observed in such devices. The protocol, which consisted of pre-conditioning steps prior to analysis, was used to further assess measurement variability from 24 individual microchips fabricated from six separate batches of glass substrate. Results show acceptable RSD percentage for retention time measurements but large variability in their corresponding peak areas (with some microchips having variability of ∼50%). Sources of variability were not related to substrate batch but possibly to a number of factors such as applied voltage fluctuations or variations in microchannel quality, for example surface roughness that will subsequently affect microchannel dimensions. PMID:23857166

  15. A minimally invasive microchip for transdermal injection/sampling applications.

    PubMed

    Strambini, Lucanos M; Longo, Angela; Diligenti, Alessandro; Barillaro, Giuseppe

    2012-09-21

    The design, fabrication, and characterization of a minimally invasive silicon microchip for transdermal injection/sampling applications are reported and discussed. The microchip exploits an array of silicon-dioxide hollow microneedles with density of one million needles cm(-2) and lateral size of a few micrometers, protruding from the front-side chip surface for one hundred micrometers, to inject/draw fluids into/from the skin. The microneedles are in connection with independent reservoirs grooved on the back-side of the chip. Insertion experiments of the microchip in skin-like polymers (agarose hydrogels with concentrations of 2% and 4% wt) demonstrate that the microneedles successfully withstand penetration without breaking, despite their high density and small size, according to theoretical predictions. Operation of the microchip with different liquids of biomedical interest (deionized water, NaCl solution, and d-glucose solution) at different differential pressures, in the range 10-100 kPa, highlights that the flow-rate through the microneedles is linearly dependent on the pressure-drop, despite the small section area (about 13 μm(2)) of the microneedle bore, and can be finely controlled from a few ml min(-1) up to tens of ml min(-1). Evaporation (at room temperature) and acceleration (up to 80 g) losses through the microneedles are also investigated to quantify the ability of the chip in storing liquids (drug to be delivered or collected fluid) in the reservoir, and result to be of the order of 70 nl min(-1) and 1300 nl min(-1), respectively, at atmospheric pressure and room temperature. PMID:22773092

  16. Solid-state detector and optical system for microchip analyzers

    DOEpatents

    Mathies, Richard A.; Kamei, Toshihiro; Scherer, James R.; Street, Robert A.

    2005-03-15

    A miniaturized optical excitation and detector system is described for detecting fluorescently labeled analytes in electrophoretic microchips and microarrays. The system uses miniature integrated components, light collection, optical fluorescence filtering, and an amorphous a-Si:H detector for detection. The collection of light is accomplished with proximity gathering and/or a micro-lens system. Optical filtering is accomplished by integrated optical filters. Detection is accomplished utilizing a-Si:H detectors.

  17. Nucleic Acid Isolation and Enrichment on a Microchip

    PubMed Central

    Kim, Jinho; Hilton, John P.; Yang, Kyung A.; Pei, Renjun; Stojanovic, Milan; Lin, Qiao

    2014-01-01

    This paper presents a microchip that isolates and enriches target-binding single-stranded DNA (ssDNA) from a randomized DNA mixture using a combination of solid-phase extraction and electrophoresis. Strands of ssDNA in a randomized mixture are captured via specific binding onto target-functionalized microbeads in a microchamber. The strands are further separated from impurities and enriched on-chip via electrophoresis. The microchip consists of two microchambers that are connected by a channel filled with agarose gel. In the isolation chamber, beads functionalized with human immunoglobulin E (IgE) are retained by a weir structure. An integrated heater elevates the temperature in the chamber to elute desired ssDNA from the beads, and electrophoretic transport of the DNA through the gel to the second chamber is accomplished by applying an electric potential difference between the two chambers. Experimental results show that ssDNA expressing binding affinity to IgE was captured and enriched from a sample of ssDNA with random sequences, demonstrating the potential of the microchip to enhance the sensitivity of ssDNA detection methods in dilute and complex biological samples. PMID:24729660

  18. Microchip separations in reduced-gravity and hypergravity environments.

    PubMed

    Culbertson, Christopher T; Tugnawat, Yogesh; Meyer, Amanda R; Roman, Gregory T; Ramsey, J Michael; Gonda, Steve R

    2005-12-15

    Microfabricated fluidics technology, e.g., lab-on-a-chip devices, offers many attractive features for performing chemistry and biochemistry on space-based platforms. We have constructed a portable, battery-operated microfluidic platform that was tested under reduced gravity and hypergravity conditions that would be experienced in space flight and launch. This device consisted of a microchip, microchip holder, two 0-8-kV high-voltage power supplies, a high-voltage switch, a solid-state diode-pumped green laser, an optical train, a channel photomultiplier, and an inertial mass measurement unit all under the control of a laptop computer and powered by 10 D-cell alkaline batteries. The unit was tested on NASA's reduced gravity research aircraft at gravity levels that are relevant to NASA's intended use of bioreporter-based microchips for environmental monitoring of space and planetary environments on manned and unmanned spacecraft. Over the course of two flights, 834 fast electrophoretic separations of four amino acids were performed under a variety of gravitational environments including zero-g, Martian-g, lunar-g, and approximately 1.8-g. All separations were performed in less than 12 s and automatically analyzed. After correction with an internal migration standard, the migration time reproducibilities were all <1% relative standard deviation. PMID:16351140

  19. Microchip system for monitoring microbial physiological behaviour under drug influences.

    PubMed

    Arora, S; Lim, C S; Foo, J Y; Sakharkar, M K; Dixit, P; Liu, A Q; Miao, J M

    2009-08-01

    Single-step real-time high-throughput monitoring of drug influences on bacterial cell behaviour has become important with growing interests in personalized therapy and medication. Conventional microchip assemblies to perform similar work do exist. However, most of these devices have complex set-ups incorporating micromixers, separators, pumps, or valves. These microcomponents can sometimes damage the entities being monitored because of the creation of unfavourable biological environments. This paper presents a microchip-based system that enables single-step mixing of two solutions in various ratios, without the need for additional microcomponents such as mixers and pumps, in order to screen effectively their combinatory effects on cell outcomes. In this work, in-vitro experiments were carried out using ampicillin at various concentrations to investigate their effects on Escherichia coli (E. coli). Results showed that the microchip provided effective screening, which yielded useful results such as effective dosages, ineffective dosages, and other possible outcomes; for instance, in this case, the occurrence of adaptive mutation of the bacteria at certain drug concentrations. Comparative microbiological laboratory tests were carried out as standard for confirmation of the results. PMID:19743643

  20. Microchip separations-based sensors for cellular analysis

    NASA Astrophysics Data System (ADS)

    Manica, Drew Prentice

    The objective of this thesis has been to introduce and develop novel methods for microchip separations for bioanalytical applications. A novel detection scheme is introduced, involving simultaneous dual amperometric and fluorescence detection on a microchip. Dual detection is shown to increase selectivity and throughput, resolve co-migrating species that may be selectively detected, and provide a convenient means to normalize for the irreproducibility of migration times often encountered in CE applications. Such normalization is expected to facilitate the use of microchip CE to monitor biological samples, which are inclined to exacerbate the irreproducibility of migration times. The use of electrochemical detection presents a unique and fundamental challenge. An effective method for reproducibly regenerating a clean surface is demonstrated. The method is optimized and utilized to achieve high sensitivity even for highly adsorptive compounds, such as those released from mast cells. The development of an in-situ electrode-cleaning protocol is an essential step toward reliably monitoring cellular release on a microchip CEEC device. Two novel techniques are presented which are capable of producing disposable microanalytical systems on glass. Electrodes and channels produced with these methods exhibit performance characteristics that are comparable to examples in current literature. These techniques demonstrate the feasibility of manufacturing a disposable glass lab-on-a-chip, which may be used for cellular analysis or as a point-of-use sensor. Increased interest in analyzing biological samples has led to the development of a wide range of derivatizing agents for biological compounds such as amino acids and peptides. A common tag that is both fluorescent and electroactive is naphthalene-2,3-dicarboxaldehyde (NDA). While there has been much discussion regarding the stability of a similar compound, o-phthalaldehyde, there has been no discussion regarding the stability of

  1. Microchip Module for Blood Sample Preparation and Nucleic Acid Amplification Reactions

    PubMed Central

    Yuen, Po Ki; Kricka, Larry J.; Fortina, Paolo; Panaro, Nicholas J.; Sakazume, Taku; Wilding, Peter

    2001-01-01

    A computer numerical control-machined plexiglas-based microchip module was designed and constructed for the integration of blood sample preparation and nucleic acid amplification reactions. The microchip module is comprised of a custom-made heater-cooler for thermal cycling, a series of 254 μm × 254 μm microchannels for transporting human whole blood and reagents in and out of an 8–9 μL dual-purpose (cell isolation and PCR) glass-silicon microchip. White blood cells were first isolated from a small volume of human whole blood (<3 μL) in an integrated cell isolation–PCR microchip containing a series of 3.5-μm feature-sized “weir-type” filters, formed by an etched silicon dam spanning the flow chamber. A genomic target, a region in the human coagulation Factor V gene (226-bp), was subsequently directly amplified by microchip-based PCR on DNA released from white blood cells isolated on the filter section of the microchip mounted onto the microchip module. The microchip module provides a convenient means to simplify nucleic acid analyses by integrating two key steps in genetic testing procedures, cell isolation and PCR and promises to be adaptable for additional types of integrated assays. PMID:11230164

  2. Comparison of Digital Rectal and Microchip Transponder Thermometry in Ferrets (Mustela putorius furo).

    PubMed

    Maxwell, Branden M; Brunell, Marla K; Olsen, Cara H; Bentzel, David E

    2016-01-01

    Body temperature is a common physiologic parameter measured in both clinical and research settings, with rectal thermometry being implied as the 'gold standard.' However, rectal thermometry usually requires physical or chemical restraint, potentially causing falsely elevated readings due to animal stress. A less stressful method may eliminate this confounding variable. The current study compared 2 types of digital rectal thermometers-a calibrated digital thermometer and a common digital thermometer-with an implantable subcutaneous transponder microchip. Microchips were implanted subcutaneously between the shoulder blades of 16 ferrets (8 male, 8 female), and temperatures were measured twice from the microchip reader and once from each of the rectal thermometers. Results demonstrated the microchip temperature readings had very good to good correlation and agreement to those from both of the rectal thermometers. This study indicates that implantable temperature-sensing microchips are a reliable alternative to rectal thermometry for monitoring body temperature in ferrets. PMID:27177569

  3. Fluorometric flow-immunoassay for alkylphenol polyethoxylates on a microchip containing a fluorescence detector comprised of an organic light emitting diode and an organic photodiode.

    PubMed

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-03-01

    A compact fluorescence detector was constructed on a microchip from an organic light emitting diode (OLED) as the light source and an organic photodiode (OPD) as the photo-detector and was used in an immunoassay for alkylphenol polyethoxylates (APE). The OLED based on a terbium complex emitted a sharp light at the main wavelength of 546 nm with a full width at half maximum of 9 nm. The incident photo-to-current conversion efficiency (IPCE) of the OPD fabricated with Fullerene 70 (C70) and tris[4-(5-phenylthiopen-2-yl)phenyl]-amine (TPTPA) was approximately 44% for light at a wavelength of 586 nm. The performance of the fluorescence detector was evaluated for the determination of resorufin (λ(em)=586 nm) and the photocurrent of the OPD due to the fluorescence of resorufin was proportional to the concentration of resorufin in the range from 0 to 18 µM with a detection limit (S/N=3) of 0.6 µM. The fluorescence detector was successfully utilized in a competitive enzyme-linked immunosorbent assay for APE, where an anti-APE antibody was immobilized on the surface of the channel of the Polydimethylsiloxane (PDMS) microchip or on the surface of magnetic microbeads. After an immunoreaction with a sample solution of APE containing a horse radish peroxidase (HRP)-labeled APE, the fluorescence of resorufin generated just after introduction of a mixed solution of Amplex Red and H2O2 was measured using the fluorescence detector. The calibration curve for the photocurrent signals of the OPD due to the fluorescence of resorufin against the logarithmic concentration of APE was sigmoidal in shape. The detection limits defined as IC80 were ca. 1 ppb and ca. 2 ppb, respectively, for the methods using the anti-APE antibody immobilized on the surface of the microchannel and in the case where the antibody was immobilized on the surface of magnetic microbeads. PMID:25618638

  4. High-sensitivity capillary and microchip electrophoresis using electrokinetic supercharging.

    PubMed

    Dawod, Mohamed; Chung, Doo Soo

    2011-10-01

    Electrokinetic supercharging (EKS) is considered as one of the most powerful online preconcentration techniques in electrophoresis. It combines the efficient preconcentration power of field-amplified sample injection and the exceptional selective nature of transient isotachophoresis. It has a wide range of applications to different types of analytes ranging from small ions to large proteins and DNA fragments. This comprehensive review--up to date--provides listing for all the works, developments, and advances in EKS. The review will pay particular attention to innovations, new methodologies for manipulation, challenges for improving the detection sensitivity, and various applications of EKS in capillaries and microchips. PMID:21793208

  5. Species-Level Identification of Orthopoxviruses with an Oligonucleotide Microchip

    PubMed Central

    Lapa, Sergey; Mikheev, Maxim; Shchelkunov, Sergei; Mikhailovich, Vladimir; Sobolev, Alexander; Blinov, Vladimir; Babkin, Igor; Guskov, Alexander; Sokunova, Elena; Zasedatelev, Alexander; Sandakhchiev, Lev; Mirzabekov, Andrei

    2002-01-01

    A method for species-specific detection of orthopoxviruses pathogenic for humans and animals is described. The method is based on hybridization of a fluorescently labeled amplified DNA specimen with the oligonucleotide DNA probes immobilized on a microchip (MAGIChip). The probes identify species-specific sites within the crmB gene encoding the viral analogue of tumor necrosis factor receptor, one of the most important determinants of pathogenicity in this genus of viruses. The diagnostic procedure takes 6 h and does not require any sophisticated equipment (a portable fluorescence reader can be used). PMID:11880388

  6. View northeast of a microchip based computer control system installed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View northeast of a microchip based computer control system installed in the early 1980's to replace Lamokin Tower, at center of photograph; panels 1 and 2 at right of photograph are part of main supervisory board; panel 1 controlled Allen Lane sub-station #7; responsiblity for this portion of the system was transferred to southeast Pennsylvania transit authority (septa) in 1985; panel 2 at extreme right controls catenary switches in a coach storage yard adjacent to the station - Thirtieth Street Station, Power Director Center, Thirtieth & Market Streets in Amtrak Railroad Station, Philadelphia, Philadelphia County, PA

  7. Diffusion of dye solution in the intermolecular nanostructure of polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Nishimura, Tatsuya; Sakiyama, Kohei; Nakagawa, Michinori

    2012-09-01

    Polydimethylsiloxane (PDMS) contains a large, flexible free space between weakly-bonded molecules, which allows notable molecular diffusion. A toluene solution of diarylethene (photochromic dye) was mixed with a PDMS oil, and then the mixture was cured in a glass vessel by adding a curing agent. Violet laser (405 nm wavelength) irradiation induced an absorption band at around 530 nm, and consequently, the irradiated portion exhibited a red color. The colored portion gradually expanded to the entire sample because of diffusion of the dye molecules. This diffusion characteristic was used for improving an organic dye durability against a photo-induced degradation.

  8. Sensitive detection of C-reactive protein in serum by immunoprecipitation-microchip capillary gel electrophoresis.

    PubMed

    Herwig, Ela; Marchetti-Deschmann, Martina; Wenz, Christian; Rüfer, Andreas; Redl, Heinz; Bahrami, Soheyl; Allmaier, Günter

    2015-06-01

    Sepsis represents a significant cause of mortality in intensive care units. Early diagnosis of sepsis is essential to increase the survival rate of patients. Among others, C-reactive protein (CRP) is commonly used as a sepsis marker. In this work we introduce immune precipitation combined with microchip capillary gel electrophoresis (IP-MCGE) for the detection and quantification of CRP in serum samples. First high-abundance proteins (HSA, IgG) are removed from serum samples using affinity spin cartridges, and then the remaining proteins are labeled with a fluorescence dye and incubated with an anti-CRP antibody, and the antigen/antibody complex is precipitated with protein G-coated magnetic beads. After precipitation the complex is eluted from the beads and loaded onto the MCGE system. CRP could be reliably detected and quantified, with a detection limit of 25 ng/μl in serum samples and 126 pg/μl in matrix-free samples. The overall sensitivity (LOQ = 75 ng/μl, R(2) = 0.9668) of the method is lower than that of some specially developed methods (e.g., immune radiometric assay) but is comparable to those of clinically accepted ELISA methods. The straightforward sample preparation (not prone to mistakes), reduced sample and reagent volumes (including the antibodies), and high throughput (10 samples/3 h) are advantages and therefore IP-MCGE bears potential for point-of-care diagnosis. PMID:25778394

  9. UV and circular dichroism thermal lens microscope for integrated chemical systems and HPLC on microchip

    NASA Astrophysics Data System (ADS)

    Mawatari, Kazuma; Kitamori, Takehiko

    2005-09-01

    Thermal lens microscope (TLM) is our original sensitive detector for non-fluorescent molecules in microspace. The principle is based on absorption of light followed by photothermal process. TLM has been successfully applied tosensitive detection on microchip, and TLM enabled various applications combined with microchip technologies. We are now developing HPLC microchips as one of the important separation techniques for analysis and synthesis. For HPLC microchip systems, direct and sensitive UV detection on microchip becomes key technology. Therefore, we extended applicability of TLM from visible to UV light absorbing samples by pulse UV laser excitation (UV-TLM). Quasi- continuous wave (QCW) method was applied for lock-in amplifier detection. By applying UV-TLM for biomolecules separation and detection, about two orders of higher sensitivity was achieved compared with UV spectrophotometer. For synthesis on microchip, recognition and detection of chiral samples become important in pharmaceutical field. Therefore, function of TLM was extended for selective detection of chiral samples by utilizing polarization modulation of excitation beam and resultant circular dichroism of sample (CD-TLM). The chirality of samples was detected selectively on microchip with two orders higher sensitivity than CD spectrophotometer. Finally, we explained the instrumentation using fiber optics and micro lens technology for achieving a miniaturized practical device.

  10. Self-transport and self-alignment of microchips using microscopic rain

    PubMed Central

    Chang, Bo; Shah, Ali; Zhou, Quan; Ras, Robin H. A.; Hjort, Klas

    2015-01-01

    Alignment of microchips with receptors is an important process step in the construction of integrated micro- and nanosystems for emerging technologies, and facilitating alignment by spontaneous self-assembly processes is highly desired. Previously, capillary self-alignment of microchips driven by surface tension effects on patterned surfaces has been reported, where it was essential for microchips to have sufficient overlap with receptor sites. Here we demonstrate for the first time capillary self-transport and self-alignment of microchips, where microchips are initially placed outside the corresponding receptor sites and can be self-transported by capillary force to the receptor sites followed by self-alignment. The surface consists of hydrophilic silicon receptor sites surrounded by superhydrophobic black silicon. Rain-induced microscopic droplets are used to form the meniscus for the self-transport and self-alignment. The boundary conditions for the self-transport have been explored by modeling and confirmed experimentally. The maximum permitted gap between a microchip and a receptor site is determined by the volume of the liquid and by the wetting contrast between receptor site and substrate. Microscopic rain applied on hydrophilic-superhydrophobic patterned surfaces greatly improves the capability, reliability and error-tolerance of the process, avoiding the need for accurate initial placement of microchips, and thereby greatly simplifying the alignment process. PMID:26450019

  11. Self-transport and self-alignment of microchips using microscopic rain

    NASA Astrophysics Data System (ADS)

    Chang, Bo; Shah, Ali; Zhou, Quan; Ras, Robin H. A.; Hjort, Klas

    2015-10-01

    Alignment of microchips with receptors is an important process step in the construction of integrated micro- and nanosystems for emerging technologies, and facilitating alignment by spontaneous self-assembly processes is highly desired. Previously, capillary self-alignment of microchips driven by surface tension effects on patterned surfaces has been reported, where it was essential for microchips to have sufficient overlap with receptor sites. Here we demonstrate for the first time capillary self-transport and self-alignment of microchips, where microchips are initially placed outside the corresponding receptor sites and can be self-transported by capillary force to the receptor sites followed by self-alignment. The surface consists of hydrophilic silicon receptor sites surrounded by superhydrophobic black silicon. Rain-induced microscopic droplets are used to form the meniscus for the self-transport and self-alignment. The boundary conditions for the self-transport have been explored by modeling and confirmed experimentally. The maximum permitted gap between a microchip and a receptor site is determined by the volume of the liquid and by the wetting contrast between receptor site and substrate. Microscopic rain applied on hydrophilic-superhydrophobic patterned surfaces greatly improves the capability, reliability and error-tolerance of the process, avoiding the need for accurate initial placement of microchips, and thereby greatly simplifying the alignment process.

  12. Effects of radiation from a radiofrequency identification (RFID) microchip on human cancer cells.

    PubMed

    Lai, Henry C; Chan, Ho Wing; Singh, Narendra P

    2016-03-01

    Purpose Radiofrequency identification (RFID) microchips are used to remotely identify objects, e.g. an animal in which a chip is implanted. A passive RFID microchip absorbs energy from an external source and emits a radiofrequency identification signal which is then decoded by a detector. In the present study, we investigated the effect of the radiofrequency energy emitted by a RFID microchip on human cancer cells. Materials and methods Molt-4 leukemia, BT474 breast cancer, and HepG2 hepatic cancer cells were exposed in vitro to RFID microchip-emitted radiofrequency field for 1 h. Cells were counted before and after exposure. Effects of pretreatment with the spin-trap compound N-tert-butyl-alpha-phenylnitrone or the iron-chelator deferoxamine were also investigated. Results We found that the energy effectively killed/retarded the growth of the three different types of cancer cells, and the effect was blocked by the spin-trap compound or the iron-chelator, whereas an inactive microchip and energy from the external source had no significant effect on the cells. Conclusions Data of the present study suggest that radiofrequency field from the microchip affects cancer cells via the Fenton Reaction. Implantation of RFID microchips in tumors may provide a new method for cancer treatment. PMID:26872622

  13. Physiological and behavioural responses of young horses to hot iron branding and microchip implantation.

    PubMed

    Erber, R; Wulf, M; Becker-Birck, M; Kaps, S; Aurich, J E; Möstl, E; Aurich, C

    2012-02-01

    Branding is the traditional and well-established method used to mark horses, but recently microchip transponders for implantation have become available. In this study, behaviour, physiological stress variables and skin temperature in foals were determined in response to hot-iron branding (n=7) and microchip implantation (n=7). Salivary cortisol concentrations increased in response to branding (1.8 ± 0.2 ng/mL) and microchip implantation (1.4 ± 0.1ng/mL), but cortisol release over time did not differ. In response to both manipulations there was a transient increase in heart rate (P<0.001) and heart rate variability (P<0.01). Branding and microchip implantation induced a comparable aversive behaviour (branding, score 3.86 ± 0.85; microchip, score 4.00 ± 0.82). Both techniques thus caused similar physiological and behavioural changes indicative of stress. Acutely, implantation of a microchip was as stressful as branding in foals. Branding caused a necrotising skin burn lasting at least 7 days. Moreover branding, but not microchip implantation (P<0.001), was accompanied by a generalized increase in skin temperature which was comparable to low degree post-burn hypermetabolism in humans. PMID:21917490

  14. Self-transport and self-alignment of microchips using microscopic rain.

    PubMed

    Chang, Bo; Shah, Ali; Zhou, Quan; Ras, Robin H A; Hjort, Klas

    2015-01-01

    Alignment of microchips with receptors is an important process step in the construction of integrated micro- and nanosystems for emerging technologies, and facilitating alignment by spontaneous self-assembly processes is highly desired. Previously, capillary self-alignment of microchips driven by surface tension effects on patterned surfaces has been reported, where it was essential for microchips to have sufficient overlap with receptor sites. Here we demonstrate for the first time capillary self-transport and self-alignment of microchips, where microchips are initially placed outside the corresponding receptor sites and can be self-transported by capillary force to the receptor sites followed by self-alignment. The surface consists of hydrophilic silicon receptor sites surrounded by superhydrophobic black silicon. Rain-induced microscopic droplets are used to form the meniscus for the self-transport and self-alignment. The boundary conditions for the self-transport have been explored by modeling and confirmed experimentally. The maximum permitted gap between a microchip and a receptor site is determined by the volume of the liquid and by the wetting contrast between receptor site and substrate. Microscopic rain applied on hydrophilic-superhydrophobic patterned surfaces greatly improves the capability, reliability and error-tolerance of the process, avoiding the need for accurate initial placement of microchips, and thereby greatly simplifying the alignment process. PMID:26450019

  15. Energy Conversion from Salinity Gradient Using Microchip with Nafion Membrane

    NASA Astrophysics Data System (ADS)

    Chang, Che-Rong; Yeh, Ching-Hua; Yeh, Hung-Chun; Yang, Ruey-Jen

    2016-06-01

    When a concentrated salt solution and a diluted salt solution are separated by an ion-selective membrane, cations and anions would diffuse at different rates depending on the ion selectivity of the membrane. The difference of positive and negative charges at both ends of the membrane would produce a potential, called the diffusion potential. Thus, electrical energy can be converted from the diffusion potential through reverse electrodialysis. This study demonstrated the fabrication of an energy conversion microchip using the standard micro-electromechanical technique, and utilizing Nafion junction as connecting membrane, which was fabricated by a surface patterned process. Through different salinity gradient of potassium chloride solutions, we experimentally investigated the diffusion potential and power generation from the microchip, and the highest value measured was 135 mV and 339 pW, respectively. Furthermore, when the electrolyte was in pH value of 3.8, 5.6, 10.3, the system exhibited best performance at pH value of 10.3; whereas, pH value of 3.8 yielded the worst.

  16. Capillary electrophoresis microchip detecting system based on embedded optical fiber

    NASA Astrophysics Data System (ADS)

    Yan, Weiping; Li, Yuanyuan; Ma, Lingzhi

    2007-12-01

    Microchip capillary electrophoresis(CE) has been recognized as a powerful tool for biochemical analyses due to its smaller size, faster separation and lower sample requirement. According to the principle of laser-induced fluorescence, the detecting system of CE microchip embedded optical fiber is discussed in this paper as well as its small volume and simple detection optical circuit. The system was composed with semiconductor laser (532nm), high voltage control system, photon counter, PC and CE chip embedded optical fibers. With the constructed detection system, different samples and different concentrations were detected, including Rhodamine B, Rhodamine 6G, and mingling solution of Rhodamine B and Rhodamine 6G. The lowest detected concentration is 1×10 -6mol/L for Rhodamine B, and 1×10 -5mol/L for Rhodamine 6G, respectively. The separation of the mingling solution of Rhodamine B and Rhodamine 6G was completed, whose concentration were both about 1×10 -4mol/L. The results show that the constructed detection system possesses some advantages, such as compact structure, higher sensitivity and repetition, which are beneficial to the development of microminiaturization and integration of micro CE chip.

  17. Analytical detection of biological thiols in a microchip capillary channel.

    PubMed

    Chand, Rohit; Jha, Sandeep Kumar; Islam, Kamrul; Han, Dawoon; Shin, Ik-Soo; Kim, Yong-Sang

    2013-02-15

    Sulfur-containing amino acids, such as cysteine and homocysteine play crucial roles in biological systems for the diagnosis of medical states. In this regard, this paper deals with separation, aliquot and detection of amino thiols on a microchip capillary electrophoresis with electrochemical detection in an inverted double Y-shaped microchannel. Unlike the conventional capillary electrophoresis, the modified microchannel design helps in storing the separated thiols in different reservoirs for further analysis, if required; and also eliminates the need of electrodes regeneration. The device was fabricated using conventional photolithographic technique which consisted of gold microelectrodes on a soda lime glass wafer and microchannels in PDMS mold. Multiple detections were performed using in-house fabricated dual potentiostat. Based on amperometric detection, cysteine and homocysteine were analyzed in 105 s and 120 s, respectively after diverting in branched channels. Repeated experiments proved the good reproducibility of the device. The device produced a linear response for both cysteine and homocysteine in electrochemical analysis. To prove the practicality of device, we also analyzed cysteine and homocysteine in real blood samples without any pre-treatment. Upon calculation, the device showed a very low limit of detection of 0.05 μM. The modified microchip design shall find a broad range of analytical applications involving assays of thiols and other biological compounds. PMID:22940195

  18. Hybridization thermodynamics of DNA oligonucleotides during microchip capillary electrophoresis.

    PubMed

    Wynne, Thomas M; McCallum, Christopher; Del Bonis-O'Donnell, Jackson Travis; Crisalli, Pete; Pennathur, Sumita

    2015-03-01

    Capillary electrophoresis (CE) is a powerful analytical tool for performing separations and characterizing properties of charged species. For reacting species during a CE separation, local concentrations change leading to nonequilibrium conditions. Interpreting experimental data with such nonequilibrium reactive species is nontrivial due to the large number of variables involved in the system. In this work we develop a COMSOL multiphysics-based numerical model to simulate the electrokinetic mass transport of short interacting ssDNAs in microchip capillary electrophoresis. We probe the importance of the dissociation constant, K(D), and the concentration of DNA on the resulting observed mobility of the dsDNA peak, μ(w), by using a full sweep of parametric simulations. We find that the observed mobility is strongly dependent on the DNA concentration and K(D), as well as ssDNA concentration, and develop a relation with which to understand this dependence. Furthermore, we present experimental microchip capillary electrophoresis measurements of interacting 10 base ssDNA and its complement with changes in buffer ionic strength, DNA concentration, and DNA sequence to vary the system equilibria. We then compare our results to thermodynamically calculated K(D) values. PMID:25634338

  19. Enhanced In Vitro Biocompatibility of Chemically Modified Poly(dimethylsiloxane) Surfaces for Stable Adhesion and Long-term Investigation of Brain Cerebral Cortex Cells.

    PubMed

    Kuddannaya, Shreyas; Bao, Jingnan; Zhang, Yilei

    2015-11-18

    Studies on the mammalian brain cerebral cortex have gained increasing importance due to the relevance of the region in controlling critical higher brain functions. Interactions between the cortical cells and surface extracellular matrix (ECM) proteins play a pivotal role in promoting stable cell adhesion, growth, and function. Poly(dimethylsiloxane) (PDMS) based platforms have been increasingly used for on-chip in vitro cellular system analysis. However, the inherent hydrophobicity of the PDMS surface has been unfavorable for any long-term cell system investigations due to transitory physical adsorption of ECM proteins on PDMS surfaces followed by eventual cell dislodgement due to poor anchorage and viability. To address this critical issue, we employed the (3-aminopropyl)triethoxysilane (APTES) based cross-linking strategy to stabilize ECM protein immobilization on PDMS. The efficiency of surface modification in supporting adhesion and long-term viability of neuronal and glial cells was analyzed. The chemically modified surfaces showed a relatively higher cell survival with an increased neurite length and neurite branching. These changes were understood in terms of an increase in surface hydrophilicity, protein stability, and cell-ECM protein interactions. The modification strategy could be successfully applied for stable cortical cell culture on the PDMS microchip for up to 3 weeks in vitro. PMID:26506436

  20. Numerical simulation and optimization of passively q-switched erbium microchip lasers

    NASA Astrophysics Data System (ADS)

    Belghachem, Nabil; Mlynczak, Jarslow

    2015-08-01

    In this article we present a procedure of optimization of passively q-switched erbium microchip lasers. The procedure is based on the rate equation model, validated by comparing the numerical results to the experimental results of pulse generation in different types of erbium/ytterbium glass microchips q-switched by Co2+ : MgAl2O4 saturable absorber. Some Degnan’s optimization limitations in case of microchip lasers were also shown and the reabsorbtion cross section of erbium glass was also estimated.

  1. [A novel and facile microchip based on nitrocellulose membrane toward efficient capture of circulating tumor cells].

    PubMed

    Zhang, Peng; Sun, Changlong; Zhang, Ren; Gao, Mingxia; Zhang, Xiangmin

    2013-06-01

    A novel and facile circulating tumor cell (CTC) microchip has been developed for the isolation and detection of cancer cells. The CTC microchip was prepared based on the nitrocellulose membrane substrate, which shows high affinity to proteins and hence can adsorb antibodies naturally. We employed non-small-cells of lung cancer NCI-H1650 as target cells and testified the high capture efficacy of the CTC microchip. Furthermore, we spiked 500 cancer cells to 1 mL healthy donor's whole blood in order to simulate the detection of CTC in patient and detected 182 cancer cells ultimately, indicating the huge application potential in the future. PMID:24063189

  2. Temperature-Induced Switchable Adhesion using Nickel–Titanium–Polydimethylsiloxane Hybrid Surfaces

    PubMed Central

    Frensemeier, Mareike; Kaiser, Jessica S; Frick, Carl P; Schneider, Andreas S; Arzt, Eduard; Fertig, Ray S; Kroner, Elmar

    2015-01-01

    A switchable dry adhesive based on a nickel–titanium (NiTi) shape-memory alloy with an adhesive silicone rubber surface has been developed. Although several studies investigate micropatterned, bioinspired adhesive surfaces, very few focus on reversible adhesion. The system here is based on the indentation-induced two-way shape-memory effect in NiTi alloys. NiTi is trained by mechanical deformation through indentation and grinding to elicit a temperature-induced switchable topography with protrusions at high temperature and a flat surface at low temperature. The trained surfaces are coated with either a smooth or a patterned adhesive polydimethylsiloxane (PDMS) layer, resulting in a temperature-induced switchable surface, used for dry adhesion. Adhesion tests show that the temperature-induced topographical change of the NiTi influences the adhesive performance of the hybrid system. For samples with a smooth PDMS layer the transition from flat to structured state reduces adhesion by 56%, and for samples with a micropatterned PDMS layer adhesion is switchable by nearly 100%. Both hybrid systems reveal strong reversibility related to the NiTi martensitic phase transformation, allowing repeated switching between an adhesive and a nonadhesive state. These effects have been discussed in terms of reversible changes in contact area and varying tilt angles of the pillars with respect to the substrate surface. PMID:26120295

  3. Monolithic composites of silica aerogels by reactive supercritical deposition of hydroxy-terminated poly(dimethylsiloxane).

    PubMed

    Sanli, D; Erkey, C

    2013-11-27

    Monolithic composites of silica aerogels with hydroxyl-terminated poly(dimethylsiloxane) (PDMS(OH)) were developed with a novel reactive supercritical deposition technique. The method involves dissolution of PDMS(OH) in supercritical CO2 (scCO2) and then exposure of the aerogel samples to this single phase mixture of PDMS(OH)-CO2. The demixing pressures of the PDMS(OH)-CO2 binary mixtures determined in this study indicated that PDMS(OH) forms miscible mixtures with CO2 at a wide composition range at easily accessible pressures. Upon supercritical deposition, the polymer molecules were discovered to react with the hydroxyl groups on the silica aerogel surface and form a conformal coating on the surface. The chemical attachment of the polymer molecules on the aerogel surface were verified by prolonged extraction with pure scCO2, simultaneous deposition with superhydrophobic and hydrophilic silica aerogel samples and ATR-FTIR analysis. All of the deposited silica aerogel samples were obtained as monoliths and retained their transparency up to around 30 wt % of mass uptake. PDMS(OH) molecules were found to penetrate all the way to the center of the monoliths and were distributed homogenously throughout the cylindrical aerogel samples. Polymer loadings as high as 75.4 wt % of the aerogel mass could be attained. It was shown that the polymer uptake increases with increasing exposure time, as well as the initial polymer concentration in the vessel. PMID:24168319

  4. Development of an air-knife system for highly reproducible fabrication of polydimethylsiloxane microstencils

    NASA Astrophysics Data System (ADS)

    Choi, Jin Ho; Kim, Gyu Man

    2015-08-01

    In this study, an air-knife system was developed for the automated fabrication of polymer microstencils with microscale perforated patterns. Blowing compressed N2 gas through the air knife provided a uniform laminar gas flow of high intensity suitable for perforating holes in the stencil. The polydimethylsiloxane (PDMS) stencil was replicated from a master mold prepared by photolithography. When the prepolymer of PDMS was spin-coated onto the master mold, a thin layer of the prepolymer remained on top of the master's structure and consequently prevented the formation of the perforated patterns. This residual layer was easily removed by the presented air knife. The air-knife system controlled the flow rate of N2 gas and the conveying speed of the master mold; therefore, the system possessed high reproducibility compared to manual gas blowing. Its use reduced the fabrication time for perforated biocompatible polymer microstencils, allowing for their mass production via an automated system. The validity of this suggested method was proven through experiments and was evaluated by application in various fields.

  5. Roll-printed organic thin-film transistor using patterned poly(dimethylsiloxane) (PDMS) stamp.

    PubMed

    Jo, Jeongdai; Yu, Jong-Su; Lee, Taik-Min; Kim, Dong-Soo; Kim, Kwang-Young

    2010-05-01

    The roll-printed gate, source, and drain electrodes of organic thin-film transistors (OTFTs) were fabricated by gravure printing or gravure-offset printing using patterned poly(dimethylsiloxane) (PDMS) stamp with various channel lengths and low-resistance silver (Ag) pastes on flexible 150 x 150 mm2 plastic substrates. Bottom-contact roll-printed OTFTs used polyvinylphenol (PVP) as polymeric dielectric and bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) as organic semiconductor; they were formed by spin coating or ink-jetting. Depending on the choice of roll-printing method, the printed OTFTs obtained had a field-effect mobility of between 0.08 and 0.1 cm2/Vs, an on/off current ratio of between 10(4) and 10(5), and a subthreshold slope of between 1.96 and 2.32 V/decade. The roll-printing using patterned PDMS stamp and soluble processes made it possible to fabricate a printed OTFT with a channel length of between 12 to 74 microm on a plastic substrate; this was not previously possible using traditional printing techniques. The proposed fabrication process was 20 steps shorted than conventional fabrication techniques. PMID:20359007

  6. Polydimethylsiloxane films doped with NdFeB powder: magnetic characterization and potential applications in biomedical engineering and microrobotics.

    PubMed

    Iacovacci, V; Lucarini, G; Innocenti, C; Comisso, N; Dario, P; Ricotti, L; Menciassi, A

    2015-12-01

    This work reports the fabrication, magnetic characterization and controlled navigation of film-shaped microrobots consisting of a polydimethylsiloxane-NdFeB powder composite material. The fabrication process relies on spin-coating deposition, powder orientation and permanent magnetization. Films with different powder concentrations (10 %, 30 %, 50 % and 70 % w/w) were fabricated and characterized in terms of magnetic properties and magnetic navigation performances (by exploiting an electromagnet-based platform). Standardized data are provided, thus enabling the exploitation of these composite materials in a wide range of applications, from MEMS/microrobot development to biomedical systems. Finally, the possibility to microfabricate free-standing polymeric structures and the biocompatibility of the proposed composite materials is demonstrated. PMID:26554861

  7. A micro gas chromatography with separation capability enhanced by polydimethylsiloxane stationary phase functionalized by carbon nanotubes and graphene.

    PubMed

    Li, Yubo; Zhang, Runzhou; Wang, Tao; Wang, Youhao; Wang, Yonghuan; Li, Lingfeng; Zhao, Weijun; Wang, Xiaozhi; Luo, Jikui

    2016-07-01

    Polydimethylsiloxane (PDMS) stationary phases functionalized with multi-walled carbon nanotubes (MWCNTs) and graphene, respectively, for the columns in micro gas chromatography are presented in this paper. To exploit the merits of MWCNTs and graphene in terms of their high specific surface area, low surface energy and chemical inertness, experimental conditions for separation (heating rate and final temperature of temperature programming, flow rate of carrier gas and the volume of samples injection) are investigated, and separations of both polar and nonpolar compound mixtures under these conditions are performed. Compared with PDMS-only coated stationary phases, the functionalization of the phases with carbon nano-materials improves the performance of columns in separation, repeatability, stability and revolution significantly. PMID:27154654

  8. Vectorial strain gauge method using single flexible orthogonal polydimethylsiloxane gratings.

    PubMed

    Guo, Hao; Tang, Jun; Qian, Kun; Tsoukalas, Dimitris; Zhao, Miaomiao; Yang, Jiangtao; Zhang, Binzhen; Chou, Xiujian; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2016-01-01

    A vectorial strain gauge method using a single sensing element is reported based on the double-sided polydimethylsiloxane (PDMS) Fraunhofer diffraction gratings structures. Using O2 plasma treatment steps, orthogonal wrinkled gratings were fabricated on both sides of a pre-strained PDMS film. Diffracted laser spots from this structure have been used to experimentally demonstrate, that any applied strain can be quantitatively characterized in both the x and y directions with an error of less than 0.6% and with a gauge factor of approximately 10. This simple and low cost technology which is completely different from the traditional vectorial strain gauge method, can be applied to surface vectorial strain measurement and multi-axis integrated mechanical sensors. PMID:27005493

  9. Enhanced triboelectrification of the polydimethylsiloxane surface by ultraviolet irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Jong Hun; Yun, Byung Kil; Jung, Jong Hoon; Park, Jeong Young

    2016-03-01

    Study of the triboelectric charging effect has recently gained much attraction by proposing a new potential technical application in the field of energy harvesting. Transparent polydimethylsiloxane (PDMS) has some advantages in employing the triboelectric effect due to good conformity at nanometer scale and the simple fabrication process. In this study, we demonstrate that UV irradiation can enhance the performance of a PDMS-based nanotribogenerator. Contact atomic force microscopy combined with Kelvin probe force microscopy enables an in-depth investigation of the effect of UV illumination on local triboelectric charge generation and its decay in PDMS. We found that UV exposure not only facilitates triboelectric charge generation but also enhances charge redistribution, which is related to the wettability of the PDMS surface. This study provides insights into the fundamental understanding and design of triboelectric generator devices.

  10. Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS).

    PubMed

    Kim, Kyeongseob; Lee, Dongju; Eom, Seunghyun; Lim, Sungjoon

    2016-01-01

    A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS). To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm) to 6.4 cm. PMID:27077861

  11. Fs-laser processing of medical grade polydimethylsiloxane (PDMS)

    NASA Astrophysics Data System (ADS)

    Atanasov, P. A.; Stankova, N. E.; Nedyalkov, N. N.; Fukata, N.; Hirsch, D.; Rauschenbach, B.; Amoruso, S.; Wang, X.; Kolev, K. N.; Valova, E. I.; Georgieva, J. S.; Armyanov, St. A.

    2016-06-01

    Medical grade polydimethylsiloxane (PDMS) elastomer is a biomaterial widely used in medicine and high-tech devices, e.g. MEMS and NEMS. In this work, we report an experimental investigation on femtosecond laser processing of PDMS-elastomer with near infrared (NIR), visible (VIS) and ultraviolet (UV) pulses. High definition trenches are produced by varying processing parameters as laser wavelength, pulse duration, fluence, scanning speed and overlap of the subsequent pulses. The sample surface morphology and chemical composition are investigated by Laser Microscopy, SEM and Raman spectroscopy, addressing the effects of the various processing parameters through comparison with the native materials characteristics. For all the laser pulse wavelengths used, the produced tracks are successfully metalized with Ni via electro-less plating method. We observe a negligible influence of the time interval elapsed between laser treatment and metallization process. Our experimental findings suggest promising perspectives of femtosecond laser pulses in micro- and nano-fabrication of hi-tech PDMS devices.

  12. Properties of ns-laser processed polydimethylsiloxane (PDMS)

    NASA Astrophysics Data System (ADS)

    Atanasov, P. A.; Stankova, N. E.; Nedyalkov, N. N.; Stoyanchov, T. R.; Nikov, Ru G.; Fukata, N.; Gerlach, J. W.; Hirsch, D.; Rauschenbach, B.

    2016-03-01

    The medical-grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial in medicine and for preparation of high-tech devices because of its remarkable properties. In this work, we present the experimental results on drilling holes on the PDMS surface by using ultraviolet, visible or near-infrared ns-laser pulses and on studying the changes of the chemical composition and structure inside the processed areas. The material in the zone of the holes is studied by XRD, ?-Raman analyses and 3D laser microscopy in order to obtain information on the influence of different processing laser parameters, as wavelength, fluence and number of consecutive pulses on the material transformation and its modification.

  13. Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS)

    PubMed Central

    Kim, Kyeongseob; Lee, Dongju; Eom, Seunghyun; Lim, Sungjoon

    2016-01-01

    A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS). To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm) to 6.4 cm. PMID:27077861

  14. Vectorial strain gauge method using single flexible orthogonal polydimethylsiloxane gratings

    PubMed Central

    Guo, Hao; Tang, Jun; Qian, Kun; Tsoukalas, Dimitris; Zhao, Miaomiao; Yang, Jiangtao; Zhang, Binzhen; Chou, Xiujian; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2016-01-01

    A vectorial strain gauge method using a single sensing element is reported based on the double-sided polydimethylsiloxane (PDMS) Fraunhofer diffraction gratings structures. Using O2 plasma treatment steps, orthogonal wrinkled gratings were fabricated on both sides of a pre-strained PDMS film. Diffracted laser spots from this structure have been used to experimentally demonstrate, that any applied strain can be quantitatively characterized in both the x and y directions with an error of less than 0.6% and with a gauge factor of approximately 10. This simple and low cost technology which is completely different from the traditional vectorial strain gauge method, can be applied to surface vectorial strain measurement and multi-axis integrated mechanical sensors. PMID:27005493

  15. Vectorial strain gauge method using single flexible orthogonal polydimethylsiloxane gratings

    NASA Astrophysics Data System (ADS)

    Guo, Hao; Tang, Jun; Qian, Kun; Tsoukalas, Dimitris; Zhao, Miaomiao; Yang, Jiangtao; Zhang, Binzhen; Chou, Xiujian; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2016-03-01

    A vectorial strain gauge method using a single sensing element is reported based on the double-sided polydimethylsiloxane (PDMS) Fraunhofer diffraction gratings structures. Using O2 plasma treatment steps, orthogonal wrinkled gratings were fabricated on both sides of a pre-strained PDMS film. Diffracted laser spots from this structure have been used to experimentally demonstrate, that any applied strain can be quantitatively characterized in both the x and y directions with an error of less than 0.6% and with a gauge factor of approximately 10. This simple and low cost technology which is completely different from the traditional vectorial strain gauge method, can be applied to surface vectorial strain measurement and multi-axis integrated mechanical sensors.

  16. Topographies of plasma-hardened surfaces of poly(dimethylsiloxane)

    SciTech Connect

    Goerrn, Patrick; Wagner, Sigurd

    2010-11-15

    We studied the formation of surface layers hardened by plasma-enhanced oxidation of the silicone elastomer poly(dimethylsiloxane). We explored the largest parameter space surveyed to date. The surface layers may wrinkle, crack, or both, under conditions that at times are controlled by design, but more often have been discovered by trial-and-error. We find four distinct topographies: flat/wrinkled/cracked/cracked and wrinkled. Each topography is clearly separated in the space of plasma dose versus plasma pressure. We analyzed wrinkle amplitude and wavelength by atomic force microscopy in the tapping mode. From these dimensions we calculated the elastic modulus and thickness of the hard surface layer, and inferred a graded hardness, by employing a modified theoretical model. Our main result is the identification of the parameters under which the technologically important pure wrinkled, crack-free topography is obtained.

  17. Enhanced sensitivity of piezoelectric pressure sensor with microstructured polydimethylsiloxane layer

    NASA Astrophysics Data System (ADS)

    Choi, Wook; Lee, Junwoo; Kyoung Yoo, Yong; Kang, Sungchul; Kim, Jinseok; Hoon Lee, Jeong

    2014-03-01

    Highly sensitive detection tools that measure pressure and force are essential in palpation as well as real-time pressure monitoring in biomedical applications. So far, measurement has mainly been done by force sensing resistors and field effect transistor (FET) sensors for monitoring biological pressure and force sensing. We report a pressure sensor by the combination of a piezoelectric sensor layer integrated with a microstructured Polydimethylsiloxane (μ-PDMS) layer. We propose an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source that is used in FET sensors, by incorporating a microstructured PDMS layer in a piezoelectric sensor. By measuring the directly induced electrical charge from the microstructure-enhanced piezoelectric signal, we observed a 3-fold increased sensitivity in a signal response. Both fast signal relaxation from force removal and wide dynamic range from 0.23 to 10 kPa illustrate the good feasibility of the thin film piezoelectric sensor for mimicking human skin.

  18. Microstructural organization of polydimethylsiloxane based polyurethane block copolymers

    NASA Astrophysics Data System (ADS)

    Hernandez, Rebeca; Weksler, Jadwiga; Padsalgikar, Ajay; Runt, James

    2007-03-01

    Microphase separation was investigated for polyurethane block copolymers synthesized from MDI and 1,4 butanediol as the hard segments, and poly(hexamethyleneoxide) (MW ˜ 700) and bis(6-hydroxyethoxypropyl) poly(dimethylsiloxane) as soft segments (MW ˜ 1000). The neat PDMS-based diol presents two segmental relaxations corresponding to the principle siloxane repeat unit and to the hydroxyethoxypropyl end group segments, respectively. When incorporated in the polyurethane, the siloxane units form a phase without intermixing with hard segments and the polyether end group segments are mixed with the second macrodiol and some short hard segment sequences. The microdomain morphology was characterized by atomic force microscopy and small-angle X-ray scattering, and the scattering data were analyzed using an approach based on a modified core-shell model. The model includes core hard segment particles (MDI-BDO), surrounded by a mixed polyether shell (PHMO and hydroxyethoxypropyl end group segments), and a matrix composed of the siloxane units.

  19. Blood-contacting properties of polydimethylsiloxane polyurea-urethanes.

    PubMed

    Hergenrother, R W; Yu, X H; Cooper, S L

    1994-06-01

    A series of polyurethanes was synthesized from amino-terminated polydimethylsiloxane oligomers of two molecular weights. The oligomers had been extended with hexane diisocyanate to give internal urea linkages in the soft segment. These polymers have been shown to have higher tensile properties over similar polymers without the internal urea linkages due to the greater phase mixing and interfacial bonding between the hard and soft segment microdomains. The surface properties of these materials were evaluated by dynamic contact angle measurements and the blood compatibility by a canine ex vivo series shunt. The silicone-urea polyurethanes had favourable blood-contacting properties compared to a polyetherurethane. The polymers composed of the higher molecular weight silicone oligomers had the least platelet and fibrinogen deposition. PMID:7948584

  20. Microchip capillary electrophoresis based electroanalysis of triazine herbicides.

    PubMed

    Islam, Kamrul; Chand, Rohit; Han, Dawoon; Kim, Yong-Sang

    2015-01-01

    The number of pesticides used in agriculture is increasing steadily, leading to contamination of soil and drinking water. Herein, we present a microfluidic platform to detect the extent of contamination in soil samples. A microchip capillary electrophoresis system with in-channel electrodes was fabricated for label-free electroanalytical detection of triazine herbicides. The sample mixture contained three representative triazines: simazine, atrazine and ametryn. The electropherogram for each individual injection of simazine, atrazine and ametryn showed peaks at 58, 66 and 72 s whereas a mixture of them showed distinct peaks at 59, 67 and 71 s respectively. The technique as such may prove to be a useful qualitative and quantitative tool for the similar environmental pollutants. PMID:25231112

  1. Microchip Electrophoresis at Elevated Temperatures and High Separation Field Strengths

    PubMed Central

    Mitra, Indranil; Marczak, Steven P.; Jacobson, Stephen C.

    2014-01-01

    We report free-solution microchip electrophoresis performed at elevated temperatures and high separation field strengths. We used microfluidic devices with 11-cm long separation channels to conduct separations at temperatures between 22 (ambient) and 45 °C and field strengths from 100 to 1000 V/cm. To evaluate separation performance, N-glycans were used as a model system and labeled with 8-aminopyrene-1,3,6-trisulfonic acid to impart charge for electrophoresis and render them fluorescent. Typically, increased diffusivity at higher temperatures leads to increased axial dispersion and poor separation performance; however, we demonstrate that sufficiently high separation field strengths can be used to offset the impact of increased diffusivity in order to maintain separation efficiency. Efficiencies for these free-solution separations are the same at temperatures of 25, 35, and 45 °C with separation field strengths ≥500 V/cm. PMID:24114979

  2. Accurate multiplex gene synthesis from programmable DNA microchips

    NASA Astrophysics Data System (ADS)

    Tian, Jingdong; Gong, Hui; Sheng, Nijing; Zhou, Xiaochuan; Gulari, Erdogan; Gao, Xiaolian; Church, George

    2004-12-01

    Testing the many hypotheses from genomics and systems biology experiments demands accurate and cost-effective gene and genome synthesis. Here we describe a microchip-based technology for multiplex gene synthesis. Pools of thousands of `construction' oligonucleotides and tagged complementary `selection' oligonucleotides are synthesized on photo-programmable microfluidic chips, released, amplified and selected by hybridization to reduce synthesis errors ninefold. A one-step polymerase assembly multiplexing reaction assembles these into multiple genes. This technology enabled us to synthesize all 21 genes that encode the proteins of the Escherichia coli 30S ribosomal subunit, and to optimize their translation efficiency in vitro through alteration of codon bias. This is a significant step towards the synthesis of ribosomes in vitro and should have utility for synthetic biology in general.

  3. Adjustable microchip ring trap for cold atoms and molecules

    SciTech Connect

    Baker, Paul M.; Stickney, James A.; Squires, Matthew B.; Scoville, James A.; Carlson, Evan J.; Buchwald, Walter R.; Miller, Steven M.

    2009-12-15

    We describe the design and function of a circular magnetic waveguide produced from wires on a microchip for atom interferometry using de Broglie waves. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent currents of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose-condensed systems.

  4. Vacuum membrane distillation by microchip with temperature gradient.

    PubMed

    Zhang, Yaopeng; Kato, Shinji; Anazawa, Takanori

    2010-04-01

    A multilayered microchip (25 x 95 mm) used for vacuum distillation is designed, fabricated and tested by rectification of a water-methanol mixture. The polymer chip employs a cooling channel to generate a temperature gradient along a distillation channel below, which is separated into a channel (72 microm deep) for liquid phase and a channel (72 microm deep) for vapor phase by an incorporated microporous poly(tetrafluoroethylene) (PTFE) membrane. The temperature gradient is controlled by adjusting hotplate temperature and flow rate of cooling water to make the temperatures in the stripping section higher than the increasing boiling points of the water-enriched liquids and the temperatures in the rectifying section lower than the decreasing dew points of the methanol-enriched vapors. The effects of temperature gradient, feed composition, feed flow rate and membrane pore size on the micro distillation are also investigated. A theoretical plate number up to 1.8 is achieved at the optimum conditions. PMID:20300677

  5. Microchip for the Measurement of Seebeck Coefficients of Single Nanowires

    NASA Astrophysics Data System (ADS)

    Völklein, F.; Schmitt, M.; Cornelius, T. W.; Picht, O.; Müller, S.; Neumann, R.

    2009-07-01

    Bismuth nanowires were electrochemically grown in ion track-etched polycarbonate membranes. Micromachining and microlithography were employed to realize a newly developed microchip for Seebeck coefficient measurements on individual nanowires. By anisotropic etching of a (100) Si wafer, an 800-nm-thick SiO2/Si3N4 membrane was prepared in the chip center. The low thermal conductivity of the membrane is crucial to obtain the required temperature difference Δ T along the nanowire. The wire is electrically contacted to thin metal pads which are patterned by a new method of microscopic exposure of photoresist and a lift-off process. A Δ T between the two pairs of contact pads, located on the membrane, is established by a thin-film heater. Applying the known Seebeck coefficient of a reference film, the temperature difference at this gap is determined. Using Δ T and the measured Seebeck voltage U of the nanowire, its Seebeck coefficient can be calculated.

  6. Affinity Monolith-Integrated Microchips for Protein Purification and Concentration.

    PubMed

    Gao, Changlu; Sun, Xiuhua; Wang, Huaixin; Qiao, Wei; Hu, Bo

    2016-01-01

    Affinity chromatography is a valuable method to purify and concentrate minute amount of proteins. Monoliths with epoxy groups for affinity immobilization were prepared by direct in-situ photopolymerization of glycidyl methacrylate and ethylene glycol dimethacrylate in porogenic solvents consisting of 1-dodecanol and cyclohexanol. By integrating affinity monoliths onto a microfluidic system, targeted biomolecules can be captured and retained on affinity column, while other biomolecules having no specific interactions toward the immobilized ligands flow through the microchannel. Therefore, proteins which remain on the affinity column are purified and concentrated, and then eluted by appropriate solutions and finally, separated by microchip capillary electrophoresis. This integrated microfluidic device has been applied to the purification and separation of specific proteins (FITC-labeled human serum albumin and IgG) in a mixture. PMID:27473483

  7. Capillary and microchip electrophoresis: challenging the common conceptions.

    PubMed

    Breadmore, Michael C

    2012-01-20

    Capillary electrophoresis (CE) has long been regarded as a powerful analytical separation technique that is an alternative to more traditional methods such as gel electrophoresis (GE) and liquid chromatography (LC). It is often touted as having a number of advantages over both of these, such as speed, flexibility, portability, sample and reagent requirements and cost, but also a number of disadvantages such as reproducibility and sensitivity. Microchip electrophoresis (ME), the next evolutionary step, miniaturised CE further providing improvements in speed and sample requirements as well as the possibility to perform more complex and highly integrated analyses. CE and ME are seen as a viable alternative to GE, but are often considered to be inferior to LC. This review will consider the strengths and weaknesses of both CE and ME and will challenge the common conceptions held about these. PMID:22000781

  8. Investigation of temperature effect on cell mechanics by optofluidic microchips

    PubMed Central

    Yang, Tie; Nava, Giovanni; Minzioni, Paolo; Veglione, Manuela; Bragheri, Francesca; Lelii, Francesca Demetra; Vazquez, Rebeca Martinez; Osellame, Roberto; Cristiani, Ilaria

    2015-01-01

    Here we present the results of a study concerning the effect of temperature on cell mechanical properties. Two different optofluidic microchips with external temperature control are used to investigate the temperature-induced changes of highly metastatic human melanoma cells (A375MC2) in the range of ~0 – 35 °C. By means of an integrated optical stretcher, we observe that cells’ optical deformability is strongly enhanced by increasing cell and buffer-fluid temperature. This finding is supported by the results obtained from a second device, which probes the cells’ ability to be squeezed through a constriction. Measured data demonstrate a marked dependence of cell mechanical properties on temperature, thus highlighting the importance of including a proper temperature-control system in the experimental apparatus. PMID:26309762

  9. Self-cleaning poly(dimethylsiloxane) film with functional micro/nano hierarchical structures.

    PubMed

    Zhang, Xiao-Sheng; Zhu, Fu-Yun; Han, Meng-Di; Sun, Xu-Ming; Peng, Xu-Hua; Zhang, Hai-Xia

    2013-08-27

    This paper reports a novel single-step wafer-level fabrication of superhydrophobic micro/nano dual-scale (MNDS) poly(dimethylsiloxane) (PDMS) films. The MNDS PDMS films were replicated directly from an ultralow-surface-energy silicon substrate at high temperature without any surfactant coating, achieving high precision. An improved deep reactive ion etching (DRIE) process with enhanced passivation steps was proposed to easily realize the ultralow-surface-energy MNDS silicon substrate and also utilized as a post-treatment process to strengthen the hydrophobicity of the MNDS PDMS film. The chemical modification of this enhanced passivation step to the surface energy has been studied by density functional theory, which is also the first investigation of C4F8 plasma treatment at molecular level by using first-principle calculations. From the results of a systematic study on the effect of key process parameters (i.e., baking temperature and time) on PDMS replication, insight into the interaction of hierarchical multiscale structures of polymeric materials during the micro/nano integrated fabrication process is experimentally obtained for the first time. Finite element simulation has been employed to illustrate this new phenomenon. Additionally, hierarchical PDMS pyramid arrays and V-shaped grooves have been developed and are intended for applications as functional structures for a light-absorption coating layer and directional transport of liquid droplets, respectively. This stable, self-cleaning PDMS film with functional micro/nano hierarchical structures, which is fabricated through a wafer-level single-step fabrication process using a reusable silicon mold, shows attractive potential for future applications in micro/nanodevices, especially in micro/nanofluidics. PMID:23906343

  10. Rapid inorganic ion analysis using quantitative microchip capillary electrophoresis.

    PubMed

    Vrouwe, Elwin X; Luttge, Regina; Olthuis, Wouter; van den Berg, Albert

    2006-01-13

    Rapid quantitative microchip capillary electrophoresis (CE) for online monitoring of drinking water enabling inorganic ion separation in less than 15 s is presented. Comparing cationic and anionic standards at different concentrations the analysis of cationic species resulted in non-linear calibration curves. We interpret this effect as a variation in the volume of the injected sample plug caused by changes of the electroosmotic flow (EOF) due to the strong interaction of bivalent cations with the glass surface. This explanation is supported by the observation of severe peak tailing. Conducting microchip CE analysis in a glass microchannel, optimized conditions are received for the cationic species K+, Na+, Ca2+, Mg2+ using a background electrolyte consisting of 30 mmol/L histidine and 2-(N-morpholino)ethanesulfonic acid, containing 0.5 mmol/L potassium chloride to reduce surface interaction and 4 mmol/L tartaric acid as a complexing agent resulting in a pH-value of 5.8. Applying reversed EOF co-migration for the anionic species Cl-, SO42- and HCO3- optimized separation occurs in a background electrolyte consisting of 10 mmol/L 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 10 mmol/L HEPES sodium salt, containing 0.05 mmol/L CTAB (cetyltrimethylammonium bromide) resulting in a pH-value of 7.5. The detection limits are 20 micromol/L for the monovalent cationic and anionic species and 10 micromol/L for the divalent species. These values make the method very suitable for many applications including the analysis of abundant ions in tap water as demonstrated in this paper. PMID:16310794

  11. Parallel analysis with optically gated sample introduction on a multichannel microchip.

    PubMed

    Xu, Hongwei; Roddy, Thomas P; Lapos, Julie A; Ewing, Andrew G

    2002-11-01

    As an alternative to the T-type injection on microchips, optically gated sample introduction previously has been demonstrated to provide fast, serial, and reproducible injections on a single-channel microchip. Here, the ability to perform high throughput, multichannel analysis with optically gated sample introduction is described using a voice coil actuator. The microchip is fixed on a stage, which moves back and forth via the voice coil actuator, scanning two laser beams across the channels on the microchip. For parallel analysis on a multichannel microchip, both the gating beam and the probe beam are scanned at 10 Hz to perform multiple injections and parallel detection. Simultaneous, fast separations of 4-choloro-7-nitrobenzofurazan (NBD)-labeled amino acids are demonstrated in multiple channels on a microchip. Serial separations of different samples in multiple channels are also reported. Optically gated sample introduction on multiple, parallel channels shows the potential for high-speed, high-throughput separations that are easily automated by using a single electronic shutter. PMID:12433082

  12. Transformations in wrinkle patterns: cooperation between nanoscale cross-linked surface layers and the submicrometer bulk in wafer-spun, plasma-treated polydimethylsiloxane.

    PubMed

    Evensen, H T; Jiang, H; Gotrik, K W; Denes, F; Carpick, R W

    2009-08-01

    We demonstrate control of the topography of strain-induced wrinkle patterns through the interplay between the bulk and the nanoscale cross-linked top layer of plasma treated, spin-coated polydimethylsiloxane (PDMS) thin films. The different morphological phases observed, varying from herringbones to caps, are in agreement with recent theoretical predictions. The cap phase exhibits short-range 3-fold-symmetric close-packed self-organization, demonstrating a bottom-up pathway toward the wafer-scale production of ordered, nanoscale patterns on surfaces. PMID:19637891

  13. Monitoring Cellular Events in Living Mast Cells Stimulated with an Extremely Small Amount of Fluid on a Microchip

    NASA Astrophysics Data System (ADS)

    Munaka, Tatsuya; Abe, Hirohisa; Kanai, Masaki; Sakamoto, Takashi; Nakanishi, Hiroaki; Yamaoka, Tetsuji; Shoji, Shuichi; Murakami, Akira

    2006-07-01

    We successfully developed a measurement system for real-time analysis of cellular function using a newly designed microchip. This microchip was equipped with a micro cell incubation chamber (240 nl) and was stimulated by a very small amount of stimuli (as small as 24 nl). Using the microchip system, cultivation of mast cells was successfully carried out. Monitoring of the cellular events after stimulation with an extremely small amount of fluid on a microchip was performed. This system could be applicable for various types of cellular analysis including real-time monitoring of cellular response by stimulation.

  14. Functionality of veterinary identification microchips following low- (0.5 tesla) and high-field (3 tesla) magnetic resonance imaging.

    PubMed

    Piesnack, Susann; Frame, Mairi E; Oechtering, Gerhard; Ludewig, Eberhard

    2013-01-01

    The ability to read patient identification microchips relies on the use of radiofrequency pulses. Since radiofrequency pulses also form an integral part of the magnetic resonance imaging (MRI) process, the possibility of loss of microchip function during MRI scanning is of concern. Previous clinical trials have shown microchip function to be unaffected by MR imaging using a field strength of 1 Tesla and 1.5. As veterinary MRI scanners range widely in field strength, this study was devised to determine whether exposure to lower or higher field strengths than 1 Tesla would affect the function of different types of microchip. In a phantom study, a total of 300 International Standards Organisation (ISO)-approved microchips (100 each of three different types: ISO FDX-B 1.4 × 9 mm, ISO FDX-B 2.12 × 12 mm, ISO HDX 3.8 × 23 mm) were tested in a low field (0.5) and a high field scanner (3.0 Tesla). A total of 50 microchips of each type were tested in each scanner. The phantom was composed of a fluid-filled freezer pack onto which a plastic pillow and a cardboard strip with affixed microchips were positioned. Following an MRI scan protocol simulating a head study, all of the microchips were accurately readable. Neither 0.5 nor 3 Tesla imaging affected microchip function in this study. PMID:23763334

  15. Development of a Real-Time Microchip PCR System for Portable Plant Disease Diagnosis

    PubMed Central

    Kim, Hyun Soo; Cifci, Osman S.; Vaughn-Diaz, Vanessa L.; Ma, Bo; Kim, Sungman; Abdel-Raziq, Haron; Ong, Kevin; Jo, Young-Ki; Gross, Dennis C.; Shim, Won-Bo; Han, Arum

    2013-01-01

    Rapid and accurate detection of plant pathogens in the field is crucial to prevent the proliferation of infected crops. Polymerase chain reaction (PCR) process is the most reliable and accepted method for plant pathogen diagnosis, however current conventional PCR machines are not portable and require additional post-processing steps to detect the amplified DNA (amplicon) of pathogens. Real-time PCR can directly quantify the amplicon during the DNA amplification without the need for post processing, thus more suitable for field operations, however still takes time and require large instruments that are costly and not portable. Microchip PCR systems have emerged in the past decade to miniaturize conventional PCR systems and to reduce operation time and cost. Real-time microchip PCR systems have also emerged, but unfortunately all reported portable real-time microchip PCR systems require various auxiliary instruments. Here we present a stand-alone real-time microchip PCR system composed of a PCR reaction chamber microchip with integrated thin-film heater, a compact fluorescence detector to detect amplified DNA, a microcontroller to control the entire thermocycling operation with data acquisition capability, and a battery. The entire system is 25×16×8 cm3 in size and 843 g in weight. The disposable microchip requires only 8-µl sample volume and a single PCR run consumes 110 mAh of power. A DNA extraction protocol, notably without the use of liquid nitrogen, chemicals, and other large lab equipment, was developed for field operations. The developed real-time microchip PCR system and the DNA extraction protocol were used to successfully detect six different fungal and bacterial plant pathogens with 100% success rate to a detection limit of 5 ng/8 µl sample. PMID:24349341

  16. Capillary liquid chromatography-microchip atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Ostman, Pekka; Jäntti, Sirkku; Grigoras, Kestas; Saarela, Ville; Ketola, Raimo A; Franssila, Sami; Kotiaho, Tapio; Kostiainen, Risto

    2006-07-01

    A miniaturized nebulizer chip for capillary liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (capillary LC-microchip APCI-MS) is presented. The APCI chip consists of two wafers, a silicon wafer and a Pyrex glass wafer. The silicon wafer has a DRIE etched through-wafer nebulizer gas inlet, an edge capillary insertion channel, a stopper, a vaporizer channel and a nozzle. The platinum heater electrode and pads for electrical connection were patterned on to the Pyrex glass wafer. The two wafers were joined by anodic bonding, creating a microchip version of an APCI-source. The sample inlet capillary from an LC column is directly connected to the vaporizer channel of the APCI chip. The etched nozzle in the microchip forms a narrow sample plume, which is ionized by an external corona needle, and the formed ions are analyzed by a mass spectrometer. The nebulizer chip enables for the first time the use of low flow rate separation techniques with APCI-MS. The performance of capillary LC-microchip APCI-MS was tested with selected neurosteroids. The capillary LC-microchip APCI-MS provides quantitative repeatability and good linearity. The limits of detection (LOD) with a signal-to-noise ratio (S/N) of 3 in MS/MS mode for the selected neurosteroids were 20-1000 fmol (10-500 nmol l(-1)). LODs (S/N = 3) with commercial macro APCI with the same compounds using the same MS were about 10 times higher. Fast heat transfer allows the use of the optimized temperature for each compound during an LC run. The microchip APCI-source provides a convenient and easy method to combine capillary LC to any API-MS equipped with an APCI source. The advantages and potentials of the microchip APCI also make it a very attractive interface in microfluidic APCI-MS. PMID:16804601

  17. Development of a real-time microchip PCR system for portable plant disease diagnosis.

    PubMed

    Koo, Chiwan; Malapi-Wight, Martha; Kim, Hyun Soo; Cifci, Osman S; Vaughn-Diaz, Vanessa L; Ma, Bo; Kim, Sungman; Abdel-Raziq, Haron; Ong, Kevin; Jo, Young-Ki; Gross, Dennis C; Shim, Won-Bo; Han, Arum

    2013-01-01

    Rapid and accurate detection of plant pathogens in the field is crucial to prevent the proliferation of infected crops. Polymerase chain reaction (PCR) process is the most reliable and accepted method for plant pathogen diagnosis, however current conventional PCR machines are not portable and require additional post-processing steps to detect the amplified DNA (amplicon) of pathogens. Real-time PCR can directly quantify the amplicon during the DNA amplification without the need for post processing, thus more suitable for field operations, however still takes time and require large instruments that are costly and not portable. Microchip PCR systems have emerged in the past decade to miniaturize conventional PCR systems and to reduce operation time and cost. Real-time microchip PCR systems have also emerged, but unfortunately all reported portable real-time microchip PCR systems require various auxiliary instruments. Here we present a stand-alone real-time microchip PCR system composed of a PCR reaction chamber microchip with integrated thin-film heater, a compact fluorescence detector to detect amplified DNA, a microcontroller to control the entire thermocycling operation with data acquisition capability, and a battery. The entire system is 25 × 16 × 8 cm(3) in size and 843 g in weight. The disposable microchip requires only 8-µl sample volume and a single PCR run consumes 110 mAh of power. A DNA extraction protocol, notably without the use of liquid nitrogen, chemicals, and other large lab equipment, was developed for field operations. The developed real-time microchip PCR system and the DNA extraction protocol were used to successfully detect six different fungal and bacterial plant pathogens with 100% success rate to a detection limit of 5 ng/8 µl sample. PMID:24349341

  18. Synthesis and morphology characterization of polydimethylsiloxane-containing block copolymers

    NASA Astrophysics Data System (ADS)

    Wadley, Maurice

    The thin film morphology characteristics of polydimethylsiloxane-containing block copolymers have been investigated. For this investigation, a commercially available hydroxyl terminated PDMS was purchased from Gelest and attached to a carboxylic acid functional reversible addition-fragmentation chain transfer (RAFT) agent by Steglich esterification. This produced macro-RAFT agents to which styrene monomer was polymerized. By using this approach the generation of low polydispersity polystyrene-block-polydimethylsiloxane (PS-block-PDMS) copolymers of various molecular weights spanning a wide volume fraction range in which the PDMS block remained the same in each polymerization. Synthesized block copolymers were characterized by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. Bulk and thin film characterization of PS-block-PDMS copolymers was done by small-angle x-ray scattering (SAXS), transmission electron microscopy (TEM), contact angle measurements, scanning force microscopy (SFM), and grazing incidence small-angle X-ray scattering (GISAXS). The following observations have been made. For PS-rich PS-block -PDMS copolymer thin films the low surface tension of PDMS caused it to migrate to the film surface regardless of solvent choice. The surface morphology was found to depend strongly on the solubility parameter of the solvent and exhibited SFM images consistent with parallel cylinder, perforated lamellar, and lamellar surface layers with increasing solvent solubility parameter. This behavior was due to the selective swelling of the individual blocks under slightly selective, good solvent conditions. A custom solvent annealing apparatus provided similar results in which order-order transitions in the thin films were observed with increasing solvent solubility parameter. Additionally improvements in the long-range order were observed after 1 h of solvent annealing. PS-rich PS-block-PDMS copolymer thin films also displayed PDMS

  19. Sol-gel modified poly(dimethylsiloxane) microfluidic devices with high electroosmotic mobilities and hydrophilic channel wall characteristics.

    PubMed

    Roman, Gregory T; Hlaus, Tyler; Bass, Kevin J; Seelhammer, Todd G; Culbertson, Christopher T

    2005-03-01

    Using a sol-gel method, we have fabricated poly(dimethylsiloxane) (PDMS) microchips with SiO2 particles homogeneously distributed within the PDMS polymer matrix. These particles are approximately 10 nm in diameter. To fabricate such devices, PDMS (Sylgard 184) was cast against SU-8 molds. After curing, the chips were carefully removed from the mold and sealed against flat, cured pieces of PDMS to form enclosed channel manifolds. These chips were then solvated in tetraethyl orthosilicate (TEOS), causing them to expand. Subsequently, the chips were placed in an aqueous solution containing 2.8% ethylamine and heated to form nanometer-sized SiO2 particles within the cross-linked PDMS polymer. The water contact angle for the PDMS-SiO2 chips was approximately 90.2 degrees compared to a water contact angle for Sylgard 184 of approximately 108.5 degrees . More importantly, the SiO2 modified PDMS chips showed no rhodamine B absorption after 4 h, indicating a substantially more hydrophilic and nonabsorptive surface than native PDMS. Initial electroosmotic mobilities (EOM) of (8.3+/-0.2)x10(-4) cm2/(V.s) (RSD=2.6% (RSD is relative standard deviation); n=10) were measured. This value was approximately twice that of native Sylgard 184 PDMS chips (4.21+/-0.09)x10(-4) cm2/(V.s) (RSD=2.2%; n=10) and 55% greater than glass chips (5.3+/-0.4)x10(-4) cm2/(V.s) (RSD=7.7%; n=5). After 60 days of dry storage, the EOM was (7.6+/-0.3)x10(-4) cm2/(V.s) (RSD=3.9%; n=3), a decrease of only 8% below that of the initially measured value. Separations performed on these devices generated 80,000-100,000 theoretical plates in 6-14 s for both tetramethylrhodamine succidimidyl ester and fluorescein-5-isothiocyanate derivatized amino acids. The separation distance was 3.5 cm. Plots of peak variance vs analyte migration times gave diffusion coefficients which indicate that the separation efficiencies are within 15% of the diffusion limit. PMID:15732926

  20. Surface Wrinkling on Polydimethylsiloxane Microspheres via Wet Surface Chemical Oxidation

    PubMed Central

    Yin, Jian; Han, Xue; Cao, Yanping; Lu, Conghua

    2014-01-01

    Here we introduce a simple low-cost yet robust method to realize spontaneously wrinkled morphologies on spherical surfaces. It is based on surface chemical oxidation of aqueous-phase-synthesized polydimethylsiloxane (PDMS) microspheres in the mixed H2SO4/HNO3/H2O solution. Consequently, curvature and overstress-sensitive wrinkles including dimples and labyrinth patterns are successfully induced on the resulting oxidized PDMS microspheres. A power-law dependence of the wrinkling wavelength on the microsphere radius exists. The effects of experimental parameters on these tunable spherical wrinkles have been systematically investigated, when the microspheres are pre-deposited on a substrate. These parameters include the radius and modulus of microspheres, the mixed acid solution composition, the oxidation duration, and the water washing post-treatment. Meanwhile, the complicated chemical oxidation process has also been well studied by in-situ optical observation via the microsphere system, which represents an intractable issue in a planar system. Furthermore, we realize surface wrinkled topographies on the whole microspheres at a large scale, when microspheres are directly dispersed in the mixed acid solution for surface oxidation. These results indicate that the introduced wet surface chemical oxidation has the great potential to apply to other complicated curved surfaces for large-scale generation of well-defined wrinkling patterns, which endow the solids with desired physical properties. PMID:25028198

  1. Candle soot nanoparticles-polydimethylsiloxane composites for laser ultrasound transducers

    NASA Astrophysics Data System (ADS)

    Chang, Wei-Yi; Huang, Wenbin; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning

    2015-10-01

    Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and -6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10-3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.

  2. Polydimethylsiloxane membranes for millimeter-wave planar ultra flexible antennas

    NASA Astrophysics Data System (ADS)

    Tiercelin, Nicolas; Coquet, Philippe; Sauleau, Ronan; Senez, Vincent; Fujita, Hiroyuki

    2006-11-01

    We present here the use of polydimethylsiloxane (PDMS) membranes as a new soft polymer substrate (ɛr ap 2.67 at 77 GHz) for the realization of ultra-flexible millimeter-wave printed antennas thanks to the extremely low Young's modulus (EPDMS < 2 MPa). Ultimately this peculiar property enables one to design wide-angle mechanically beam-steering antennas and flexible conformal antennas. The experimental characterization of PDMS material in V- and W-bands highlights high loss tangent values (tanδ ap 0.04 at 77 GHz). Thus micromachining techniques have been developed to reduce dielectric losses for antenna applications at millimeter waves. Here the antenna performance is demonstrated in the 60 GHz band by considering a single microstrip patch antenna supported by a PDMS membrane over an air-filled cavity. After a brief description of the design approach using the method of moments (MoM) and the finite-difference time-domain (FDTD) technique, the technological processes are described in detail. The input impedance and radiation patterns of the prototype are in good agreement with numerical simulations. The radiation efficiency of the micromachined antenna is equal to 60% and is in the same order as that obtained with conventional polymer bulk substrates such as Duroids. These results confirm the validity of the new technological process and assembly procedure, and demonstrate that PDMS membranes can be used to realize low-loss planar membrane-supported millimeter-wave printed circuits and radiating structures.

  3. Fibroblast extracellular matrix and adhesion on microtextured polydimethylsiloxane scaffolds.

    PubMed

    Stanton, Morgan M; Parrillo, Allegra; Thomas, Gawain M; McGimpsey, W Grant; Wen, Qi; Bellin, Robert M; Lambert, Christopher R

    2015-05-01

    The immediate physical and chemical surroundings of cells provide important biochemical cues for their behavior. Designing and tailoring biomaterials for controlled cell signaling and extracellular matrix (ECM) can be difficult due to the complexity of the cell-surface relationship. To address this issue, our research has led to the development of a polydimethylsiloxane (PDMS) scaffold with defined microtopography and chemistry for surface driven ECM assembly. When human fibroblasts were cultured on this microtextured PDMS with 2-6 µm wide vertical features, significant changes in morphology, adhesion, actin cytoskeleton, and fibronectin generation were noted when compared with cells cultured on unmodified PDMS. Investigation of cellular response and behavior was performed with atomic force microscopy in conjunction with fluorescent labeling of focal adhesion cites and fibronectin in the ECM. Changes in the surface topography induced lower adhesion, an altered actin cytoskeleton, and compacted units of fibronectin similar to that observed in vivo. Overall, these findings provide critical information of cell-surface interactions with a microtextured, polymer substrate that can be used in the field of tissue engineering for controlling cellular ECM interactions. PMID:25142015

  4. Polydimethylsiloxane bilayer films with an embedded spontaneous curvature.

    PubMed

    Egunov, A I; Korvink, J G; Luchnikov, V A

    2016-01-01

    Elastomer polydimethylsiloxane (PDMS) films with embedded in-plane gradient stress are created by making PDMS/(PDMS + silicone oil) crosslinked bilayers and extracting the oil in a suitable organic solvent bath. The collapse of the elastomer after oil extraction generates differential stress in the films that is manifested through their out-of-plane deformation. The curvature κ of narrow stripes of the bilayer, which is composed of layers of approximately equal thicknesses and elasticity moduli, is satisfactorily described by the simple relationship κ = 1.5δH(-1), where δ is the mechanical strain, and H is the total thickness of the bilayer. Curvature mapping of triangular PDMS plates reveals the existence of spherical and cylindrical types of deformation at different locations of the plates. Various 3D-shaped objects can be formed by the self-folding of appropriately designed 2D patterns that are cut from the films, or by nonuniform distribution of the collapsing layer. Thin PDMS bilayers with embedded stress roll up into microtubes of almost perfect cylindrical shape when released in a controlled manner from a substrate. PMID:26539638

  5. Simple room temperature bonding of thermoplastics and poly(dimethylsiloxane).

    PubMed

    Sunkara, Vijaya; Park, Dong-Kyu; Hwang, Hyundoo; Chantiwas, Rattikan; Soper, Steven A; Cho, Yoon-Kyoung

    2011-03-01

    We describe a simple and versatile method for bonding thermoplastics to elastomeric polydimethylsiloxane (PDMS) at room temperature. The bonding of various thermoplastics including polycarbonate (PC), cyclic olefin copolymer (COC), polymethylmethacrylate (PMMA), and polystyrene (PS), to PDMS has been demonstrated at room temperature. An irreversible bonding was formed instantaneously when the thermoplastics, activated by oxygen plasma followed by aminopropyltriethoxysilane modification, were brought into contact with the plasma treated PDMS. The surface modified thermoplastics were characterized by water contact angle measurements and X-ray photoelectron spectroscopy. The tensile strength of the bonded hybrid devices fabricated with PC, COC, PMMA, and PS was found to be 430, 432, 385, and 388 kPa, respectively. The assembled devices showed high burst resistance at a maximum channel pressure achievable by an in-house built syringe pump, 528 kPa. Furthermore, they displayed very high hydrolytic stability; no significant change was observed even after the storage in water at 37 °C over a period of three weeks. In addition, this thermoplastic-to-PDMS bonding technique has been successfully employed to fabricate a relatively large sized device. For example, a lab-on-a-disc with a diameter of 12 cm showed no leakage when it spins for centrifugal fluidic pumping at a very high rotating speed of 6000 rpm. PMID:21152492

  6. Automated Lipid Bilayer Membrane Formation Using a Polydimethylsiloxane Thin Film.

    PubMed

    Choi, Sangbaek; Yoon, Sunhee; Ryu, Hyunil; Kim, Sun Min; Jeon, Tae-Joon

    2016-01-01

    An artificial lipid bilayer, or black lipid membrane (BLM), is a powerful tool for studying ion channels and protein interactions, as well as for biosensor applications. However, conventional BLM formation techniques have several drawbacks and they often require specific expertise and laborious processes. In particular, conventional BLMs suffer from low formation success rates and inconsistent membrane formation time. Here, we demonstrate a storable and transportable BLM formation system with controlled thinning-out time and enhanced BLM formation rate by replacing conventionally used films (polytetrafluoroethylene, polyoxymethylene, polystyrene) to polydimethylsiloxane (PDMS). In this experiment, a porous-structured polymer such as PDMS thin film is used. In addition, as opposed to conventionally used solvents with low viscosity, the use of squalene permitted a controlled thinning-out time via slow solvent absorption by PDMS, prolonging membrane lifetime. In addition, by using a mixture of squalene and hexadecane, the freezing point of the lipid solution was increased (~16 °C), in addition, membrane precursors were produced that can be indefinitely stored and readily transported. These membrane precursors have reduced BLM formation time of < 1 hr and achieved a BLM formation rate of ~80%. Moreover, ion channel experiments with gramicidin A demonstrated the feasibility of the membrane system. PMID:27501114

  7. Random lasing action in a polydimethylsiloxane wrinkle induced disordered structure

    SciTech Connect

    Shen, Zhenhua; Wu, Leilei; Zhu, Shu; Zheng, Yuanlin; Chen, Xianfeng

    2014-07-14

    This paper presents a chip-scale random lasing action utilizing polydimethylsiloxane (PDMS) wrinkles with random periods as disordered medium. Nanoscale wrinkles with long range disorder structures are formed on the oxidized surface of a PDMS slab and confirmed by atomic force microscopy. Light multiply scattered at each PDMS wrinkle-dye interfaces is optically amplified in the presence of pump gain. The shift of laser emission wavelength when pumping at different regions indicates the randomness of the winkle period. In addition, a relatively low threshold of about 27 μJ/mm{sup 2} is realized, which is comparable with traditional optofluidic dye laser. This is due to the unique sinusoidal Bragg-grating-like random structure. Contrast to conventional microfluidic dye laser that inevitably requires the accurate design and implementation of microcavity to provide optical feedback, the convenience in both fabrication and operation makes PDMS wrinkle based random laser a promising underlying element in lab-on-a-chip systems and integrated microfluidic networks.

  8. Gas chromatography-microchip atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Ostman, Pekka; Luosujärvi, Laura; Haapala, Markus; Grigoras, Kestas; Ketola, Raimo A; Kotiaho, Tapio; Franssila, Sami; Kostiainen, Risto

    2006-05-01

    An atmospheric pressure chemical ionization (APCI) microchip is presented for combining a gas chromatograph (GC) to a mass spectrometer (MS). The chip includes capillary insertion channel, stopper, vaporizer channel, nozzle and nebulizer gas inlet fabricated on the silicon wafer, and a platinum heater sputtered on a glass wafer. These two wafers are joined by anodic bonding creating a two-dimensional version of an APCI microchip. The sample from GC is directed via heated transfer line capillary to the vaporizer channel of the APCI chip. The etched nozzle forms narrow sample plume, which is ionized by an external corona discharge needle, and the ions are analyzed by a mass spectrometer. The GC-microchip APCI-MS combination provides an efficient method for qualitative and quantitative analysis. The spectra produced by microchip APCI show intensive protonated molecule and some fragmentation products as in classical chemical ionization for structure elucidation. In quantitative analysis the GC-microchip APCI-MS showed good linearity (r(2) = 0.9989) and repeatability (relative standard deviation 4.4%). The limits of detection with signal-to-noise ratio of three were between 0.5 and 2 micromol/L with MS mode using selected ion monitoring and 0.05 micromol/L with MS/MS using multiple reaction monitoring. PMID:16642989

  9. Fabrication of SU-8 based microchip electrophoresis with integrated electrochemical detection for neurotransmitters.

    PubMed

    Castaño-Alvarez, Mario; Fernández-Abedul, M Teresa; Costa-García, Agustín; Agirregabiria, María; Fernández, Luis J; Ruano-López, Jesús Miguel; Barredo-Presa, Borja

    2009-11-15

    A new SU-8 based microchip capillary electrophoresis (MCE) device has been developed for the first time with integrated electrochemical detection. Embedded electrophoretic microchannels have been fabricated with a multilayer technology based on bonding and releasing steps of stacked SU-8 films. This technology has allowed the monolithic integration in the device of the electrochemical detection system based on platinum electrodes. The fabrication of the chips presented in this work is totally compatible with reel-to-reel techniques, which guarantee a low cost and high reliability production. The influence of relevant experimental variables, such as the separation voltage and detection potential, has been studied on the SU-8 microchip with an attractive analytical performance. Thus, the effective electrical isolation of the end-channel amperometric detector has been also demonstrated. The good performance of the SU-8 device has been proven for separation and detection of the neurotransmitters, dopamine (DA) and epinephrine (EP). High efficiency (30,000-80,000 N/m), excellent precision, good detection limit (450 nM) and resolution (0.90-1.30) has been achieved on the SU-8 microchip. These SU-8 devices have shown a better performance than commercial Topas (thermoplastic olefin polymer of amorphous structure) microchips. The low cost and versatile SU-8 microchip with integrated platinum film electrochemical detector holds great promise for high-volume production of disposable microfluidic analytical devices. PMID:19782188

  10. Generating high peak capacity 2-D maps of complex proteomes using PMMA microchip electrophoresis.

    PubMed

    Osiri, John K; Shadpour, Hamed; Park, Sunjung; Snowden, Brandy C; Chen, Zhi-Yuan; Soper, Steven A

    2008-12-01

    A high peak capacity 2-D protein separation system combining SDS micro-CGE (SDS micro-CGE) with microchip MEKC (micro-MEKC) using a PMMA microfluidic is reported. The utility of the 2-D microchip was demonstrated by generating a 2-D map from a complex biological sample containing a large number of constituent proteins using fetal calf serum (FCS) as the model system. The proteins were labeled with a thiol-reactive AlexaFluor 633 fluorophore (excitation/emission: 633/652 nm) to allow for ultra-sensitive on-chip detection using LIF following the 2-D separation. The high-resolution separation of the proteins was accomplished based on their size in the SDS micro-CGE dimension and their interaction with micelles in the micro-MEKC dimension. A comprehensive 2-D SDS micro-CGE x micro-MEKC separation of the FCS proteins was completed in less than <30 min using this 2-D microchip format, which consisted of 60 mm and 50 mm effective separation lengths for the first and second separation dimensions, respectively. Results obtained from the microchip separation were compared with protein maps acquired using conventional 2-D IEF and SDS-PAGE of a similar FCS sample. The microchip 2-D separation was found to be approximately 60x faster and yielded an average peak capacity of 2600 (+/- 149), nearly three times larger than that obtained using conventional IEF/SDS-PAGE. PMID:19130578

  11. A Sol-Gel-Modified Poly(methyl methacrylate) Electrophoresis Microchip with a Hydrophilic Channel Wall

    SciTech Connect

    Chen, Gang; Xu, Xuejiao; Lin, Yuehe; Wang, Joseph

    2007-07-27

    A sol-gel method was employed to fabricate a poly(methyl methacrylate) (PMMA) electrophoresis microchip that contains a hydrophilic channel wall. To fabricate such a device, tetraethoxysilane (TEOS) was injected into the PMMA channel and was allowed to diffuse into the surface layer for 24 h. After removing the excess TEOS, the channel was filled with an acidic solution for 3 h. Subsequently, the channel was flushed with water and was pretreated in an oven to obtain a sol-gel-modified PMMA microchip. The water contact angle for the sol-gel-modified PMMA was 27.4° compared with 66.3° for the pure PMMA. In addition, the electro-osmotic flow increased from 2.13×10-4 cm2 V-1 s-1 for the native-PMMA channel to 4.86×10-4 cm2 V-1 s-1 for the modified one. The analytical performance of the sol-gel-modified PMMA microchip was demonstrated for the electrophoretic separation of several purines, coupled with amperometric detection. The separation efficiency of uric acid increased to 74 882.3 m-1 compared with 14 730.5 m-1 for native-PMMA microchips. The result of this simple modification is a significant improvement in the performance of PMMA for microchip electrophoresis and microfluidic applications.

  12. Large-scale simulation of flow and transport in reconstructed HPLC-microchip packings.

    PubMed

    Khirevich, Siarhei; Höltzel, Alexandra; Ehlert, Steffen; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

    2009-06-15

    Flow and transport in a particle-packed microchip separation channel were investigated with quantitative numerical analysis methods, comprising the generation of confined, polydisperse sphere packings by a modified Jodrey-Tory algorithm, 3D velocity field calculations by the lattice-Boltzmann method, and modeling of convective-diffusive mass transport with a random-walk particle-tracking approach. For the simulations, the exact conduit cross section, the particle-size distribution of the packing material, and the respective average interparticle porosity (packing density) of the HPLC-microchip packings was reconstructed. Large-scale simulation of flow and transport at Peclet numbers of up to Pe = 140 in the reconstructed microchip packings (containing more than 3 x 10(5) spheres) was facilitated by the efficient use of supercomputer power. Porosity distributions and fluid flow velocity profiles for the reconstructed microchip packings are presented and analyzed. Aberrations from regular geometrical conduit shape are shown to influence packing structure and, thus, porosity and velocity distributions. Simulated axial dispersion coefficients are discussed with respect to their dependence on flow velocity and bed porosity. It is shown by comparison to experimental separation efficiencies that the simulated data genuinely reflect the general dispersion behavior of the real-life HPLC-microchip packings. Differences between experiment and simulation are explained by differing morphologies of real and simulated packings (intraparticle porosity, packing structure in the corner regions). PMID:19459621

  13. Antifouling and antimicrobial mechanism of tethered quaternary ammonium salts in a cross-linked poly(dimethylsiloxane) matrix studied using sum frequency generation vibrational spectroscopy.

    PubMed

    Ye, Shuji; Majumdar, Partha; Chisholm, Bret; Stafslien, Shane; Chen, Zhan

    2010-11-01

    Poly(dimethylsiloxane) (PDMS) materials containing chemically bound (''tethered'') quaternary ammonium salt (QAS) moieties are being developed as new contact-active antimicrobial coatings. Such coatings are designed to inhibit the growth of microorganisms on surfaces for a variety of applications which include ship hulls and biomedical devices. The antimicrobial activity of these coatings is a function of the molecular surface structure generated during film formation. Sum frequency generation (SFG) vibrational spectroscopy has been demonstrated to be a powerful technique to study polymer surface structures at the molecular level in different chemical environments. SFG was successfully used to characterize the surface structures of PDMS coatings containing tethered QAS moieties that possess systematic variations in QAS chemical composition in air, in water, and in a nutrient growth medium. The results indicated that the surface structure was largely dependent on the length of the alkyl chain attached to the nitrogen atom of the QAS moiety as well as the length of alkyl chain spanning between the nitrogen atom and silicon atom of the QAS moiety. The SFG results correlated well with the antimicrobial activity, providing a molecular interpretation of the activity. This research showed that SFG can be effectively used to aid in the development of new antimicrobial coating technologies by correlating the chemical structure of a coating surface to its antimicrobial activity. PMID:20345165

  14. Surface forces and protein adsorption on dextran- and polyethylene glycol-modified polydimethylsiloxane.

    PubMed

    Farrell, Megan; Beaudoin, Stephen

    2010-12-01

    Dextran and polyethylene glycol (PEG) are often covalently bound to the surface of polydimethylsiloxane (PDMS) for the purpose of modifying its hydrophilicity and biocompatibility. In this work, the effects of the dextran and PEG on the morphology, wetting, and surface charge of the resulting surfaces were quantified and correlated with changes in the amount of fibrinogen and albumin adsorbed from aqueous solution. PDMS films were functionalized in a microwave oxygen plasma to create surface hydroxyl groups that were subsequently aminated by incubation in a (3-aminopropyl)trimethoxysilane (APTES) solution. Oxidized dextran and PEG-aldehyde were linked to the surface amines via reductive amination. This process resulted in low surface coverage of immobilized PEG in the end-on conformation and a more uniform and dense distribution of side-on immobilized dextran. The immobilized dextran reduced the contact angle of the PDMS film from 109° to 80° and neutralized the zeta potential over the pH range from 3 to 11. An atomic force microscope was used to measure the interaction force between the modified PDMS and a model hydrophobic surface (polystyrene latex) and a model hydrophilic surface (silica) in aqueous solution to show that van der Waals and hydrophobic attractive forces are the dominant forces for protein adsorption in this system. The PEG- and dextran-modified PDMS were exposed to BSA and fibrinogen to test their resistance to protein adsorption. The coatings were ineffective at reducing the adsorption of either molecule, and the dextran-modification of the PDMS caused more BSA to adsorb than in the case of the unmodified PDMS. PMID:20801620

  15. Surface Forces and Protein Adsorption on Dextran- and Polyethylene Glycol-Modified Polydimethylsiloxane

    PubMed Central

    Farrell, Megan; Beaudoin, Stephen

    2010-01-01

    Dextran and polyethylene glycol (PEG) are often covalently bound to the surface of polydimethylsiloxane (PDMS) for the purpose of modifying its hydrophilicity and biocompatibility. In this work, the effects of the dextran and PEG on the morphology, wetting, and surface charge of the resulting surfaces were quantified and correlated with changes in the amount of fibrinogen and albumin adsorbed from aqueous solution. PDMS films were functionalized in a microwave oxygen plasma to create surface hydroxyl groups that were subsequently aminated by incubation in a (3-aminopropyl)trimethoxysilane (APTES) solution. Oxidized dextran and PEG-aldehyde were linked to the surface amines via reductive amination. This process resulted in low surface coverage of immobilized PEG in the end-on conformation and a more uniform and dense distribution of side-on immobilized dextran. The immobilized dextran reduced the contact angle of the PDMS film from 109° to 80° and neutralized the zeta potential over the pH range from 3 to 11. An atomic force microscope was used to measure the interaction force between the modified PDMS and a model hydrophobic surface (polystyrene latex) and a model hydrophilic surface (silica) in both water and electrolyte solutions to show that van der Waals and hydrophobic attractive forces are the dominant forces for protein adsorption in this system. The PEG- and dextran-modified PDMS were exposed to BSA and fibrinogen to test their resistance to protein adsorption. The coatings were ineffective at reducing the adsorption of either molecule, and the dextran-modification of the PDMS caused more BSA to adsorb than in the case of the unmodified PDMS. PMID:20801620

  16. Monolithic thermally bonded Er3+, Yb3+:glass/Co2+:MgAl2O4 microchip lasers

    NASA Astrophysics Data System (ADS)

    Mlynczak, Jaroslaw; Belghachem, Nabil

    2015-12-01

    The highest ever reported 10 kW peak power in monolithic thermally bonded Er3+, Yb3+:glass/Co2+:MgAl2O4 microchip laser was achieved. To show the superiority of monolithic microchip lasers over those with external mirrors the laser generation characteristics of the same samples in both cases were compared.

  17. Microchip-based forensic short tandem repeat genotyping.

    PubMed

    Kim, Yong Tae; Heo, Hyun Young; Oh, Shin Hye; Lee, Seung Hwan; Kim, Do Hyun; Seo, Tae Seok

    2015-08-01

    Micro total analysis system (μTAS) or lab-on-a-chip (LOC) technology has advanced over decades, and the high performance for chemical and biological analysis has been well demonstrated with advantages of low sample consumption, rapid analysis time, high-throughput screening, and portability. In particular, μTAS or LOC based genetic applications have been extensively explored, and the short tandem repeat (STR) typing on a chip has garnered attention in the forensic community due to its special use for human identification in the field of mass disaster and missing person investigation, paternity testing, and perpetrator identification. The STR typing process consists of sample collection, DNA extraction, DNA quantitation, STR loci amplification, capillary electrophoretic separation, and STR profiling. Recent progress of microtechnology shows its ability to substitute the conventional analytical tools, and furthermore demonstrates total integration of the whole STR processes on a single wafer for on-site STR typing. In this review article, we highlighted some representative results for fluorescence labeling techniques, microchip-based DNA purification, on-chip polymerase chain reaction (PCR), a capillary electrophoretic microdevice, and a fully integrated microdevice for STR typing. PMID:25963560

  18. Microchip-Based Organophosphorus Detection Using Bienzyme Bioelectrocatalysis

    NASA Astrophysics Data System (ADS)

    Han, Yong Duk; Jeong, Chi Yong; Lee, Jun Hee; Lee, Dae-Sik; Yoon, Hyun C.

    2012-06-01

    We have developed a microsystem for the detection of organophosphorus (OP) compounds using acetylcholine esterase (AchE) and choline oxidase (ChOx) bienzyme bioelectrocatalysis. Because AchE is irreversibly inhibited by OP pesticides, the change in AchE activity with OP treatment can be traced to determine OP concentration. Polymer-associated ChOx immobilization on the working electrode surface and magnetic microparticle (MP)-assisted AchE deposition methods were employed to create an AchE-ChOx bienzyme-modified biosensing system. ChOx was immobilized on the micropatterned electrodes using poly(L-lysine), glutaraldehyde, and amine-rich interfacial surface. AchE was immobilized on the MP surface via Schiff's base formation, and the enzyme-modified MPs were deposited on the working electrode using a magnet under the microfluidic channel. The bioelectrocatalytic reaction between AchE-ChOx bienzyme cascade and the ferrocenyl electron shuttle was successfully used to detect OP with the developed microchip. This provides a self-contained and relatively easy method for OP detection. It requires minimal time and a small sample size, and has potential analytic applications in pesticides and chemical warfare agents.

  19. Integrated liquid chromatography-heated nebulizer microchip for mass spectrometry.

    PubMed

    Haapala, Markus; Saarela, Ville; Pól, Jaroslav; Kolari, Kai; Kotiaho, Tapio; Franssila, Sami; Kostiainen, Risto

    2010-03-10

    A new integrated microchip for liquid chromatography-mass spectrometry (LC-MS) is presented. The chip is made from bonded silicon and glass wafers with structures for a packed LC column channel, a micropillar frit, a channel for optional optical detection, and a heated vaporizer section etched in silicon and platinum heater elements on the glass cover. LC eluent is vaporized and mixed with nebulizer gas in the vaporizer section and the vapor is sprayed out from the chip. Nonpolar and polar analytes can be efficiently ionized in the gas phase by atmospheric pressure photoionization (APPI) as demonstrated with polycyclic aromatic hydrocarbons (PAHs) and selective androgen receptor modulators (SARMs). This is not achievable with present LC-MS chips, since they are based on electrospray ionization, which is not able to ionize nonpolar compounds efficiently. The preliminary quantitative performance of the new chip was evaluated in terms of limit of detection (down to 5 ng mL(-1)), linearity (r>0.999), and repeatability of signal response (RSD=2.6-4.0%) and retention time (RSD=0.3-0.5%) using APPI for ionization and PAHs as standard compounds. Determination of fluorescent compounds is demonstrated by using laser-induced fluorescence (LIF) for detection in the optical detection channel before the vaporizer section. PMID:20171315

  20. Measuring protein interactions by microchip self-interaction chromatography.

    PubMed

    García, Carlos D; Hadley, DeGail J; Wilson, W William; Henry, Charles S

    2003-01-01

    The self-interaction of proteins is of paramount importance in aggregation and crystallization phenomena. Solution conditions leading to a change in the state of aggregation of a protein, whether amorphous or crystalline, have mainly been discovered by the use of trial and error screening of large numbers of solutions. Self-interaction chromatography has the potential to provide a quantitative method for determination of protein self-interactions amenable to high-throughput screening. This paper describes the construction and characterization of a microchip separation system for low-pressure self-interaction chromatography using lysozyme as a model protein. The retention time was analyzed as a function of mobile-phase composition, amount of protein injected, flow rate, and stationary-phase modification. The capacity factors (k') as a function of crystallizing agent concentration are compared with previously published values for the osmotic second virial coefficient (B(22)) obtained by static light scattering, showing the ability of the chip to accurately determine protein-protein interactions. A 500-fold reduction in protein consumption and the possibility of using conventional instrumentation and automation are some of the advantages over currently used methodologies for evaluating protein-protein interactions. PMID:12790668

  1. Implementation of microchip electrophoresis instrumentation for future spaceflight missions.

    PubMed

    Willis, Peter A; Creamer, Jessica S; Mora, Maria F

    2015-09-01

    We present a comprehensive discussion of the role that microchip electrophoresis (ME) instrumentation could play in future NASA missions of exploration, as well as the current barriers that must be overcome to make this type of chemical investigation possible. We describe how ME would be able to fill fundamental gaps in our knowledge of the potential for past, present, or future life beyond Earth. Despite the great promise of ME for ultrasensitive portable chemical analysis, to date, it has never been used on a robotic mission of exploration to another world. We provide a current snapshot of the technology readiness level (TRL) of ME instrumentation, where the TRL is the NASA systems engineering metric used to evaluate the maturity of technology, and its fitness for implementation on missions. We explain how the NASA flight implementation process would apply specifically to ME instrumentation, and outline the scientific and technology development issues that must be addressed for ME analyses to be performed successfully on another world. We also outline research demonstrations that could be accomplished by independent researchers to help advance the TRL of ME instrumentation for future exploration missions. The overall approach described here for system development could be readily applied to a wide range of other instrumentation development efforts having broad societal and commercial impact. PMID:26253225

  2. A Contactless Capacitance Detection System for Microchip Capillary Electrophoresis

    NASA Astrophysics Data System (ADS)

    Wu, Peter

    2008-05-01

    The design, construction and operation of a simple, inexpensive and compact high voltage power supply for use in conjunction with a simple cross, capillary electrophoresis microchip is presented. The detection system utilizes a single high voltage power supply (15 kV), a voltage divider network for obtaining the required voltages for enabling a gated injection valve, and two high voltage relays for switching between the open and closed gate sequences of the injection. The system is used to determine sodium monofluoroacetate (MFA) concentration in diluted fruit juices and tap water. A separation buffer consisting of 20 mM citric acid and histidine at pH 3.5 enabled the detection of the anion in diluted apple juice, cranberry juice, and orange juice without lengthy sample pretreatments. Limit of detection in diluted juices and tap water were determined to be 125, 167, 138, and 173 mg/L for tap water, apple juice, cranberry juice, and orange juice, respectively, based upon an S/N of 3:1. The total analysis time for detecting the MFA anion in fruit juices was less than 5 min, which represents a considerable reduction in analysis time compared to other analytical methods currently used in food analysis.

  3. Comparison of Noncontact Infrared Thermometry and 3 Commercial Subcutaneous Temperature Transponding Microchips with Rectal Thermometry in Rhesus Macaques (Macaca mulatta)

    PubMed Central

    Brunell, Marla K

    2012-01-01

    This study compared a noncontact infrared laser thermometer and 3 different brands of subcutaneous temperature transponding microchips with rectal thermometry in 50 rhesus macaques (Macaca mulatta). The data were analyzed by using intraclass correlation coefficients and limits of agreement. In addition, the technical capabilities and practicality of the thermometers in the clinical setting were reviewed. None of the alternative techniques investigated was equivalent to rectal thermometry in rhesus macaques. Temperatures obtained by using microchips had higher correlation and agreed more closely with rectal temperatures than did those obtained by the noncontact infrared method. However, transponding microchips did not yield consistent results. Due to difficulty in positioning nonsedated macaques in their homecage, subcutaneous microchips were not practical in the clinical setting. Furthermore, pair-housed macaques may be able to break or remove microchips from their cagemates. PMID:23043815

  4. Effect of anti-biofouling potential of multi-walled carbon nanotubes-filled polydimethylsiloxane composites on pioneer microbial colonization.

    PubMed

    Sun, Yuan; Lang, Yanhe; Sun, Qian; Liang, Shuang; Liu, Yongkang; Zhang, Zhizhou

    2016-09-01

    In this paper, two carbon nanotube (CNT) nanofillers, namely the multi-walled carbon nanotubes (MWCNTs) and the carboxyl-modified MWCNTs (cMWCNTs), were introduced into the polydimethylsiloxane (PDMS) matrix respectively, in order to produce the PDMS composites with reinforced anti-biofouling properties. The anti-biofouling capacity of the silicone-based coatings, including the unfilled PDMS (P0), the MWCNTs-filled PDMS (PM) and the cMWCNTs-filled PDMS (PC), was examined via the field assays conducted in Weihai, China. The effect of different silicone-based coatings on the dynamic variations of the pioneer microbial-community diversity was analyzed using the single-strand conformation polymorphism (SSCP) technique. The PM and PC surfaces have exhibited excellent anti-biofouling properties in contrast to that of the PDMS surface, with extremely low attachment of the early colonizers, such as juvenile invertebrates, seaweeds and algae sporelings. The PM and PC surfaces can effectively prevent biofouling for more than 12 weeks. These combined results suggest that the incorporation of MWCNTs or cMWCNTs into the PDMS matrix can dramatically reinforce its anti-biofouling properties. The SSCP analysis reveals that compared with the PDMS surfaces, the PM and PC surfaces have strong modulating effect on the pioneer prokaryotic and eukaryotic communities, particularly on the colonization of pioneer eukaryotic microbes. The significantly reduced pioneer eukaryotic-community diversity may contribute to the weakening of the subsequent colonization of macrofoulers. PMID:27137800

  5. Micropatterning of poly(dimethylsiloxane) using a photoresist lift-off technique for selective electrical insulation of microelectrode arrays

    PubMed Central

    Park, Jaewon; Kim, Hyun Soo; Han, Arum

    2009-01-01

    A poly(dimethylsiloxane) (PDMS) patterning method based on a photoresist lift-off technique to make an electrical insulation layer with selective openings is presented. The method enables creating PDMS patterns with small features and various thicknesses without any limitation in the designs and without the need for complicated processes or expensive equipments. Patterned PDMS layers were created by spin-coating liquid phase PDMS on top of a substrate having sacrificial photoresist patterns, followed by a photoresist lift-off process. The thickness of the patterned PDMS layers could be accurately controlled (6.5–24 µm) by adjusting processing parameters such as PDMS spin-coating speeds, PDMS dilution ratios, and sacrificial photoresist thicknesses. PDMS features as small as 15 µm were successfully patterned and the effects of each processing parameter on the final patterns were investigated. Electrical resistance tests between adjacent electrodes with and without the insulation layer showed that the patterned PDMS layer functions properly as an electrical insulation layer. Biocompatibility of the patterned PDMS layer was confirmed by culturing primary neuron cells on top of the layer for up to two weeks. An extensive neuronal network was successfully formed, showing that this PDMS patterning method can be applied to various biosensing microdevices. The utility of this fabrication method was further demonstrated by successfully creating a patterned electrical insulation layer on flexible substrates containing multi-electrode arrays. PMID:19946385

  6. Impact of conduit geometry on the performance of typical particulate microchip packings.

    PubMed

    Jung, Stephanie; Höltzel, Alexandra; Ehlert, Steffen; Mora, Jose-Angel; Kraiczek, Karsten; Dittmann, Monika; Rozing, Gerard P; Tallarek, Ulrich

    2009-12-15

    This work investigates the impact of conduit geometry on the chromatographic performance of typical particulate microchip packings. For this purpose, high-performance liquid chromatography (HPLC)/UV-microchips with separation channels of quadratic, trapezoidal, or Gaussian cross section were fabricated by direct laser ablation and lamination of multiple polyimide layers and then slurry-packed with either 3 or 5 microm spherical porous C8-silica particles under optimized packing conditions. Experimentally determined plate height curves for the empty microchannels are compared with dispersion coefficients from theoretical calculations. Packing densities and plate height curves for the various microchip packings are presented and conclusively explained. The 3 microm packings display a high packing density irrespective of their conduit geometries, and their performance reflects the dispersion behavior of the empty channels. Dispersion in 5 microm packings correlates with the achieved packing densities, which are limited by the number and accessibility of corners in a given conduit shape. PMID:19916548

  7. A review of microdialysis coupled to microchip electrophoresis for monitoring biological events

    PubMed Central

    Saylor, Rachel A.; Lunte, Susan M.

    2015-01-01

    Microdialysis is a powerful sampling technique that enables monitoring of dynamic processes in vitro and in vivo. The combination of microdialysis with chromatographic or electrophoretic methods yields along with selective detection methods yields a “separation-based sensor” capable of monitoring multiple analytes in near real time. Analysis of microdialysis samples requires techniques that are fast (<1 min), have low volume requirements (nL–pL), and, ideally, can be employed on-line. Microchip electrophoresis fulfills these requirements and also permits the possibility of integrating sample preparation and manipulation with detection strategies directly on-chip. Microdialysis coupled to microchip electrophoresis has been employed for monitoring biological events in vivo and in vitro. This review discusses technical considerations for coupling microdialysis sampling and microchip electrophoresis, including various interface designs, and current applications in the field. PMID:25637011

  8. Microchip-based enzyme-linked immunosorbent assay (microELISA) system with thermal lens detection.

    PubMed

    Sato, Kiichi; Yamanaka, Maho; Hagino, Tomokazu; Tokeshi, Manabu; Kimura, Hiroko; Kitamori, Takehiko

    2004-12-01

    A microchip-based enzyme-linked immunosorbent assay (microELISA) system was developed and interferon-gamma was successfully determined. The system was composed of a microchip with a Y-shaped microchannel and a dam structure, polystyrene microbeads, and a thermal lens microscope (TLM). All reactions required for the immunoassay were done in the microchannel by successive introduction of a sample and regents. The enzyme reaction product, in a liquid phase, was detected downstream in the channel using the TLM as substrate solution was injected. The antigen-antibody reaction time was shortened by the microchip integration. The limit of the determination was improved by adopting the enzyme label. Moreover, detection procedures were greatly simplified and required time for the detection was significantly cut. The system has good potential to be developed as a small and automated high throughput analyzer. PMID:15570367

  9. Optical properties of polydimethylsiloxane (PDMS) during nanosecond laser processing

    NASA Astrophysics Data System (ADS)

    Stankova, N. E.; Atanasov, P. A.; Nikov, Ru. G.; Nikov, R. G.; Nedyalkov, N. N.; Stoyanchov, T. R.; Fukata, N.; Kolev, K. N.; Valova, E. I.; Georgieva, J. S.; Armyanov, St. A.

    2016-06-01

    This article presents experimental investigations of effects of the process parameters on the medical grade polydimethylsiloxane (PDMS) elastomer processed by laser source with irradiation at UV (266 and 355 nm), VIS (532 nm) and NIR (1064 nm). Systematic experiments are done to characterize how the laser beam parameters (wavelength, fluence, and number of pulses) affect the optical properties and the chemical composition in the laser treated areas. Remarkable changes of the optical properties and the chemical composition are observed. Despite the low optical absorption of the native PDMS for UV, VIS and NIR wavelengths, successful laser treatment is accomplished due to the incubation process occurring below the polymer surface. With increasing of the fluence and the number of the pulses chemical transformations are revealed in the entire laser treated area and hence decreasing of the optical transmittance is observed. The incubation gets saturation after a certain number of pulses and the laser ablation of the material begins efficiently. At the UV and VIS wavelengths the number of the initial pulses, at which the optical transmittance begins to reduce, decreases from 16 up to 8 with increasing of the laser fluence up to 1.0, 2.5 and 10 J cm-2 for 266, 355 and 532 nm, respectively. In the case of 1064 nm the optical transmittance begins to reduce at 11th pulse incident at a fluence of 13 J cm-2 and the number of the pulses decreases to 8 when the fluence reaches value of 16 J cm-2. The threshold laser fluence needed to induce incubation process after certain number of pulses of 8 is different for every wavelength irradiation as the values increase from 1.0 for 266 nm up to 16 J cm-2 for 1064 nm. The incubation and the ablation processes occur in the PDMS elastomer material during its pulsed laser treatment are a complex function of the wavelength, fluence, number of pulses and the material properties as well.

  10. Geometric optics of gold nanoparticle-polydimethylsiloxane thin films

    NASA Astrophysics Data System (ADS)

    Dunklin, Jeremy R.; Forcherio, Gregory T.; Roper, D. Keith

    2014-09-01

    Interest in the optical properties of plasmonic nanoparticles embedded in transparent polymers is expanding due to potential uses in sustainability, biomedicine, and manufacturing. Geometric optics of polydimethylsiloxane (PDMS) thin films containing uniformly or asymmetrically distributed polydisperse reduced gold nanoparticles (AuNPs) or uniformly distributed monodisperse solution synthesized AuNPs were recently evaluated using a compact linear algebraic sum. Algebraic calculation of geometric transmission, reflection, and attenuation for AuNP-PDMS films provides a simple, workable alternative to effective medium approximations, computationally expensive methods, and fitting of experimental data. Generally, transmission and reflection increased with AuNP isotropy and particle density, as displayed on a novel ternary diagram. Irregular AuNP morphology and size distribution caused optical attenuation from polydisperse films to increase in proportion to log10 increases in gold content, resulting in lower attenuation per gold mass when compared to monodisperse AuNPs. Uniform monodisperse AuNP-PDMS films attenuated light in proportion to gold content, with films attenuating 0.15 fractional units per 0.1 mass-percent AuNPs. Thin layers of concentrated AuNPs attenuated light more efficiently. A 25 micron thick layer of 1.2 mass-percent AuNPs attenuated 0.5 fractional units, the same number as a 130 micron thick 0.6 mass-percent film. Measured optical responses from asymmetric AuNP-PDMS films with an adjacent back-reflector and pairs of uniformly distributed films were predictable within 0.04 units of linear algebraic estimates based on geometric optics. This approach allows for the summative optical responses of a sequence of 2D elements comprising a 3D assembly to be analyzed.

  11. Culture of bovine embryos on a polydimethylsiloxane (PDMS) microwell plate.

    PubMed

    Akagi, Satoshi; Hosoe, Misa; Matsukawa, Kazutsugu; Ichikawa, Akihiko; Tanikawa, Tamio; Takahashi, Seiya

    2010-08-01

    We fabricated a polydimethylsiloxane (PDMS)-based microwell plate (PDMS-MP) containing 100 microwells with a rounded bottom and examined whether it can be used for culture of individual in vitro fertilized (IVF) embryos or parthenogenetically activated zona-free embryos in cattle. In Experiment 1, we examined the in vitro developmental ability of IVF embryos cultured individually on PDMS-MP. After IVF, 20 embryos were transferred into 100 microl drops on PDMS-MP and cultured individually in each well of PDMS-MP (PDMS group). After 7 days of culture, the embryos in the PDMS group developed to the blastocyst stage at the same rate of those in the control group cultured in a group of 20 embryos without PDMS-MP. There were no differences in total number of cells and the ratio of inner cell mass to total cells between the PDMS and control groups. In Experiment 2, we examined the in vitro developmental ability of parthenogenetically activated zona-free bovine embryos cultured individually on PDMS-MP. The zona-free embryos were cultured individually in each well of a PDMS-MP or in each well produced by pressing a darning needle onto the bottom of a culture dish (WOW group). After 7 days of culture, the blastocyst formation rate and cell number of blastocysts in the PDMS group did not differ from those of the zona-intact embryos in the control group. Also, there were no differences in the blastocyst formation rate and cell number of blastocysts between the WOW and PDMS groups. These results suggest that the culture system using PDMS-MP is useful for individual embryos or zona-free embryos in cattle. PMID:20484872

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

    PubMed Central

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

    2009-01-01

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

  13. Functional thermal lens microscopes for ultrasensitive analysis of non-fluorescent molecules and microchip chemistry

    NASA Astrophysics Data System (ADS)

    Mawatari, Kazuma; Kitamori, Takehiko

    2006-09-01

    Thermal lens microscope (TLM) is a kind of absorption spectrophotometry based on photothermal phenomena of non-fluorescent molecules. TLM has high sensitivity (single molecule concentration in fL detection volume) and wide applicability (non-fluorescent molecules). TLM was successfully applied to detection on microchip in clinical diagnosis, environmental analysis, single cell analysis and so on. The basic function of TLM is concentration determination in microspace. In addition, we have realized various functions on TLM for sensitive chiral analysis, individual nanoparticle counting and in situ flow sensing. In this presentation, we explain these functional TLMs for microchip chemistry.

  14. Microchips fabricated by femtosecond laser micromachining in glass for observation of aquatic microorganisms

    NASA Astrophysics Data System (ADS)

    Hanada, Y.; Sugioka, K.; Kawano, H.; Ishikawa, I.; Miyawaki, A.; Midorikawa, K.

    2008-02-01

    We demonstrate the fabrication of three-dimensional (3D) hollow microstructures embedded in photostructurable glass by a nonlinear multiphoton absorption process using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D hollow microstructures for the dynamic observation of living microorganisms in fresh water. The embedded microchannel structure enables us to analyze the continuous motion of Euglena gracilis and Dinoflagellate. Such microchips, referred to as nano-aquariums realize the efficient and highly functional observation of microorganisms.

  15. Chemiluminescence resonance energy transfer-based detection for microchip electrophoresis.

    PubMed

    Zhao, Shulin; Huang, Yong; Shi, Ming; Liu, Rongjun; Liu, Yi-Ming

    2010-03-01

    Since the channels in micro- and nanofluidic devices are extremely small, a sensitive detection is required following microchip electrophoresis (MCE). This work describes a highly sensitive and yet universal detection scheme based on chemiluminescence resonance energy transfer (CRET) for MCE. It was found that an efficient CRET occurred between a luminol donor and a CdTe quantum dot (QD) acceptor in the luminol-NaBrO-QD system and that it was sensitively suppressed by the presence of certain organic compounds of biological interest including biogenic amines and thiols, amino acids, organic acids, and steroids. These findings allowed developing sensitive MCE-CL assays for the tested compounds. The proposed MCE-CL methods showed desired analytical figures of merit such as a wide concentration range of linear response. Detection limits obtained were approximately 10(-9) M for biogenic amines including dopamine and epinephrine and approximately 10(-8) M for biogenic thiols (e.g., glutathione and acetylcysteine), organic acids (i.e., ascorbic acid and uric acid), estrogens, and native amino acids. These were 10-1000 times more sensitive than those of previously reported MCE-based methods with chemiluminescence, electrochemical, or laser-induced fluorescence detection for quantifying corresponding compounds. To evaluate the applicability of the present MCE-CL method for analyzing real biological samples, it was used to determine amino acids in individual human red blood cells. Nine amino acids, including Lys, Ser, Ala, Glu, Trp, etc., were detected. The contents ranged from 3 to 31 amol/cell. The assay proved to be simple, quick, reproducible, and very sensitive. PMID:20121202

  16. Highly Transparent and Flexible Triboelectric Nanogenerators with Subwavelength-Architectured Polydimethylsiloxane by a Nanoporous Anodic Aluminum Oxide Template.

    PubMed

    Dudem, Bhaskar; Ko, Yeong Hwan; Leem, Jung Woo; Lee, Soo Hyun; Yu, Jae Su

    2015-09-23

    Highly transparent and flexible triboelectric nanogenerators (TENGs) were fabricated using the subwavelength-architectured (SWA) polydimethylsiloxane (PDMS) with a nanoporous anodic aluminum oxide (AAO) template as a replica mold. The SWA PDMS could be utilized as a multifunctional film for a triboelectric layer, an antireflection coating, and a self-cleaning surface. The nanopore arrays of AAO were formed by a simple, fast, and cost-effective electrochemical oxidation process of aluminum, which is relatively impressive for fabrication of the TENG device. For electrical contacts, the SWA PDMS was laminated on the indium tin oxide (ITO)-coated polyethylene terephthalate (PET) as a bottom electrode, and the bare ITO-coated PET (i.e., ITO/PET) was used for the top electrode. Compared to the ITO/PET, the SWA PDMS on the ITO/PET improved the transmittance from 80.5 to 83% in the visible wavelength region and also had high transmittances of >85% at wavelengths of 430-455 nm. The SWA PDMS also exhibited the hydrophobic surface with a water contact angle (θCA) of ∼115°, which can be useful for self-cleaning applications. The average transmittance (Tavg) of the entire TENG device was observed to be ∼70% over a broad wavelength range. At an external pushing frequency of 0.5 Hz, for the TENG device with the ITO top electrode, open-circuit voltage (VOC) and short-circuit current (ISC) values of ∼3.8 V and ∼0.8 μA were obtained instantaneously, respectively, which were higher than those (i.e., VOC ≈ 2.2 V, and ISC ≈ 0.4 μA) of the TENG device with a gold top electrode. The effect of external pushing force and frequency on the output device performance of the TENGs was investigated, including the device robustness. A theoretical optical analysis of SWA PDMS was also performed. PMID:26301328

  17. Poly(ethylene glycol)-functionalized polymeric microchips for capillary electrophoresis.

    PubMed

    Sun, Xuefei; Li, Dan; Lee, Milton L

    2009-08-01

    Recently, we reported the synthesis, fabrication, and preliminary evaluation of poly(ethylene glycol) (PEG)-functionalized polymeric microchips that are inherently resistant to protein adsorption without surface modification in capillary electrophoresis (CE). In this study, we investigated the impact of cross-linker purity and addition of methyl methacrylate (MMA) as a comonomer on CE performance. Impure poly(ethylene glycol) diacrylate (PEGDA) induced electroosmotic flow (EOF) and increased the separation time, while the addition of MMA decreased the separation efficiency to approximately 25% of that obtained using microchips fabricated without MMA. Resultant improved microchips were evaluated for the separation of fluorescent dyes, amino acids, peptides, and proteins. A CE efficiency of 4.2 x 10(4) plates for aspartic acid in a 3.5 cm long microchannel was obtained. Chiral separation of 10 different D,L-amino acid pairs was obtained with addition of a chiral selector (i.e., beta-cyclodextrin) in the running buffer. Selectivity (alpha) and resolution (R(s)) for D,L-leucine were 1.16 and 1.64, respectively. Good reproducibility was an added advantage of these PEG-functionalized microchips. PMID:19572700

  18. On-chip pumping for pressure mobilization of the focused zones following microchip isoelectric focusing.

    PubMed

    Guillo, Christelle; Karlinsey, James M; Landers, James P

    2007-01-01

    Isoelectric focusing (IEF), traditionally accomplished in slab or tube gels, has also been performed extensively in capillary and, more recently, in microchip formats. IEF separations performed in microchips typically use electroosmotic flow (EOF) or chemical treatment to mobilize the focused zones past the detection point. This report describes the development and optimization of a microchip IEF method in a hybrid PDMS-glass device capable of controlling the mobilization of the focused zones past the detector using on-chip diaphragm pumping. The microchip design consisted of a glass fluid layer (separation channels), a PDMS layer and a glass valve layer (pressure connections and valve seats). Pressure mobilization was achieved on-chip using a diaphragm pump consisting of a series of reversible elastomeric valves, where a central diaphragm valve determined the volume of solution displaced while the gate valves on either side imparted directionality. The pumping rate could be adjusted to control the mobilization flow rate by varying the actuation times and pressure applied to the PDMS to actuate the valves. In order to compare the separation obtained using the chip with that obtained in a capillary, a serpentine channel design was used to match the separation length of the capillary, thereby evaluating the effect of diaphragm pumping itself on the overall separation quality. The optimized mIEF method was applied to the separation of labeled amino acids. PMID:17180213

  19. Microchip transponder thermometry for monitoring core body temperature of antelope during capture.

    PubMed

    Rey, Benjamin; Fuller, Andrea; Hetem, Robyn S; Lease, Hilary M; Mitchell, Duncan; Meyer, Leith C R

    2016-01-01

    Hyperthermia is described as the major cause of morbidity and mortality associated with capture, immobilization and restraint of wild animals. Therefore, accurately determining the core body temperature of wild animals during capture is crucial for monitoring hyperthermia and the efficacy of cooling procedures. We investigated if microchip thermometry can accurately reflect core body temperature changes during capture and cooling interventions in the springbok (Antidorcas marsupialis), a medium-sized antelope. Subcutaneous temperature measured with a temperature-sensitive microchip was a weak predictor of core body temperature measured by temperature-sensitive data loggers in the abdominal cavity (R(2)=0.32, bias >2 °C). Temperature-sensitive microchips in the gluteus muscle, however, provided an accurate estimate of core body temperature (R(2)=0.76, bias=0.012 °C). Microchips inserted into muscle therefore provide a convenient and accurate method to measure body temperature continuously in captured antelope, allowing detection of hyperthermia and the efficacy of cooling procedures. PMID:26724197

  20. A microchip-based model wound with multiple types of cells.

    PubMed

    Xie, Yunyan; Zhang, Wei; Wang, Liming; Sun, Kang; Sun, Yi; Jiang, Xingyu

    2011-09-01

    Collective migration is critical to many physiological processes, but few methods allow for studying this behavior with precisely controlled cell-cell interaction. Here we report the development of a microchip based on co-culture of different types of cells and selective injury, and explore the dynamics of epithelial collective migration triggered by a real cell group. PMID:21776534

  1. Enhanced Detection of Proteins in Microchip Separations by On-Chip Preconcentration

    SciTech Connect

    Foote, R.S.

    2001-05-24

    Microfluidic chips incorporating a semiporous glass filter were used to electrokinetically concentrate proteins on-chip prior to injection and electrophoretic analysis. Signal enhancements of >100-fold could be achieved for the microchip analysis of both native and SDS-denatured proteins using this technique.

  2. Rapid amplification of genetically modified organisms using a circular ferrofluid-driven PCR microchip.

    PubMed

    Sun, Yi; Kwok, Yien-Chian; Foo-Peng Lee, Peter; Nguyen, Nam-Trung

    2009-07-01

    The use of genetically modified organisms (GMOs) as food and in food products is becoming more and more widespread. Polymerase chain reaction (PCR) technology is extensively used for the detection of GMOs in food products in order to verify compliance with labeling requirements. In this paper, we present a novel close-loop ferrofluid-driven PCR microchip for rapid amplification of GMOs. The microchip was fabricated in polymethyl methacrylate by CO2 laser ablation and was integrated with three temperature zones. PCR solution was contained in a circular closed microchannel and was driven by magnetic force generated by an external magnet through a small oil-based ferrofluid plug. Successful amplification of genetically modified soya and maize were achieved in less than 13 min. This PCR microchip combines advantages of cycling flexibility and quick temperature transitions associated with two existing microchip PCR techniques, and it provides a cost saving and less time-consuming way to conduct preliminary screening of GMOs. PMID:19399482

  3. Fast screening of rice knockout mutants by multi-channel microchip electrophoresis.

    PubMed

    Nan, He; Lee, Sang-Won; Kang, Seong Ho

    2012-08-15

    A multi-channel microchip electrophoresis (MC-ME) system with a laser-induced fluorescence detector was developed for the fast simultaneous detection of rice knockout mutants in genetically modified (GM) rice. In addition, three parallel separation channels were fabricated on a glass microchip to investigate the possibility of high-throughput screening of amplified-polymerase chain reaction products representing wild-type rice and mutants. The MC-ME system was developed to simultaneously record data on all channels using specifically designed electrodes for an even distribution of electric fields, an expanded laser beam for excitation, a 10× objective lens to capture emissions, and a charge coupled device camera for detection. Under a programmed electric field strength and a sieving gel matrix of 0.7% poly(ethylene oxide) (M(r)=8,000,000), T-DNA-inserted rice mutants, two standard wild-type rice lines, and six rice knockout mutants were analyzed within 4 min using three parallel channels on the microchip. Compared to conventional microchip electrophoresis, the MC-ME method is a valid and practical way to effectively analyze multiple samples in parallel for the identification of GM rice without any loss of resolving power or reproducibility. The MC-ME method was more than 15 times faster than traditional slab gel electrophoresis and proved to be a powerful tool for high-throughput screening of GM rice with high sensitivity, efficiency, and reproducibility. PMID:22841075

  4. A low timing jitter picosecond microchip laser pumped by pulsed LD

    NASA Astrophysics Data System (ADS)

    Wang, Sha; Wang, Yan-biao; Feng, Guoying; Zhou, Shou-huan

    2016-07-01

    SESAM passively Q-switched microchip laser is a very promising instrument to replace mode locked lasers to obtain picosecond pulses. The biggest drawback of a passively Q-switched microchip laser is its un-avoided large timing jitter, especially when the pump intensity is low, i.e. at low laser repetition rate range. In order to obtain a low timing jitter passively Q-switched picosecond microchip laser in the whole laser repetition rate range, a 1000 kHz pulsed narrow bandwidth Fiber Bragg Grating (FBG) stablized laser diode was used as the pump source. By tuning the pump intensity, we could control the output laser frequency. In this way, we achieved a very low timing jitter passively Q-switched picosecond laser at 2.13 mW, 111.1 kHz. The relative timing jitter was only 0.0315%, which was around 100 times smaller compared with a cw LD pumped microchip working at hundred kilohertz repetition rate frequency range.

  5. A Microchip for Quantitative Analysis of CNS Axon Growth under Localized Biomolecular Treatments

    PubMed Central

    Park, Jaewon; Kim, Sunja; Park, Su Inn; Choe, Yoonsuck; Li, Jianrong; Han, Arum

    2013-01-01

    Growth capability of neurons is an essential factor in axon regeneration. To better understand how microenvironments influence axon growth, methods that allow spatial control of cellular microenvironments and easy quantification of axon growth are critically needed. Here, we present a microchip capable of physically guiding the growth directions of axons while providing physical and fluidic isolation from neuronal somata/dendrites that enables localized biomolecular treatments and linear axon growth. The microchip allows axons to grow in straight lines inside the axon compartments even after the isolation; therefore, significantly facilitating the axon length quantification process. We further developed an image processing algorithm that automatically quantifies axon growth. The effect of localized extracellular matrix components and brain-derived neurotropic factor treatments on axon growth was investigated. Results show that biomolecules may have substantially different effects on axon growth depending on where they act. For example, while chondroitin sulfate proteoglycan causes axon retraction when added to the axons, it promotes axon growth when applied to the somata. The newly developed microchip overcomes limitations of conventional axon growth research methods that lack localized control of biomolecular environments and are often performed at a significantly lower cell density for only a short period of time due to difficulty in monitoring of axonal growth. This microchip may serve as a powerful tool for investigating factors that promote axon growth and regeneration. PMID:24161788

  6. Toward point-of-care testing for JAK2 V617F mutation on a microchip.

    PubMed

    Wang, Hua; Liu, Weiwei; Zhang, Xinju; Xu, Xiao; Kang, Zhihua; Li, Shibao; Wu, Zhiyuan; Yang, Zhiliu; Yao, Bo; Guan, Ming

    2015-09-01

    Molecular genetics now plays a crucial role in diagnosis, the identification of prognostic markers, and monitoring of hematological malignancies. Demonstration of acquired changes such as the JAK2 V617F mutation within myeloproliferative neoplasms (MPN) has quickly moved from a research setting to the diagnostic laboratory. Microfluidics-based assays can reduce the assay time and sample/reagent consumption and enhance the reaction efficiency; however, no current assay has integrated isothermal amplification for point-of-care MPN JAK2 V617F mutation testing with a microchip. In this report, an integrated microchip that performs the whole human blood genomic DNA extraction, loop-mediated isothermal nucleic acid amplification (LAMP) and visual detection for point-of-care genetic mutation testing is demonstrated. This method was validated on DNA from cell lines as well as on whole blood from patients with MPN. The results were compared with those obtained by unlabeled probe melting curve analysis. This chip enjoys a high accuracy, operability, and cost/time efficiency within 1h. All these benefits provide the chip with a potency toward a point-of-care genetic analysis. All samples identified as positive by unlabeled probe melting curve analysis (n=27) proved positive when tested by microchip assay. None of the 30 negative controls gave false positive results. In addition, a patient with polycythemia vera diagnosed as being JAK2 V617F-negative by unlabeled probe melting curve analysis was found to be positive by the microchip. This microchip would possibly be very attractive in developing a point-of-care platform for quick preliminary diagnosis of MPN or other severe illness in resource-limited settings. PMID:26235214

  7. A Novel Protocol to Analyze Short- and Long-Chain Fatty Acids Using Nonaqueous Microchip Capillary Electrophoresis

    NASA Technical Reports Server (NTRS)

    Cable, M. L.; Stockton, A. M.; Mora, Maria F; Willis, P. A.

    2013-01-01

    We propose a new protocol to identify and quantify both short- and long-chain saturated fatty acids in samples of astrobiological interest using non-aqueous microchip capillary electrophoresis (micronNACE) with laser induced fluorescence (LIF).

  8. A precision hot embossing mold fabricated by high-resolution powder blasting with polydimethylsiloxane and SU-8 masking technology

    NASA Astrophysics Data System (ADS)

    Lomas, T.; Wisitsoraat, A.; Chevasuvit, F.; Tuantranont, A.

    2009-03-01

    In this paper, we applied a three-dimensional micromold by using micropowder and micropattern masking technology. High-resolution powder blasting with polydimethylsiloxane (PDMS) and SU-8 masking is developed for the fabrication of a precision microfluidic mold for hot embossing fabrication. The PDMS is a suitable masking material for powder blasting due to its high erosion resistance. First, a 100 µm SU-8 negative pattern was developed on a stainless steel substrate by standard photolithography. A PDMS solution was then applied to the substrate, mainly filling recessed regions. Excess of PDMS was then physically removed by a blade. The PDMS/SU-8 structure was then cured. Next, silicon carbine (SiC) powder with an average diameter of 50 µm was blasted on a PDMS/SU-8 coated stainless sheet at a constant pressure between 4 and 6 bar and a PDMS mask was removed by ultrasonic cleaning in isopropanol. The three-dimensional structure was examined by an optical microscope, optical white light interferometer and scanning electron microscope. The PDMS pattern is found to be 50 µm wide, and the maximum etched depth at this thickness is around 150 µm at a blasting pressure of 6.2 bar; thus, an aspect ratio of 3 is easily obtained. In principle, the low-cost micromachining hot embossing mold developed can be improved to yield submicrometer- and nanometer-scale resolution.

  9. A novel sorptive extraction method based on polydimethylsiloxane frit for determination of lung cancer biomarkers in human serum.

    PubMed

    Xu, Hui; Wang, Shuyu

    2012-04-29

    In this study, a porous polypropylene frit was coated with polydimethylsiloxane (PDMS) as extraction medium, based on the home-made PDMS-frit, a rapid, simple and sensitive sorptive extraction method was established for analysis of potential biomarkers of lung cancer (hexanal and heptanal) in human serum samples. In the method, derivatization and extraction occurred simultaneously on the PDMS-frit, then the loaded frit was ultrasonically desorbed in acetonitrile. Polymerization, derivatization-extraction and desorption conditions were optimized. Under the optimal conditions, satisfactory results were gained, a wide linear application range was obtained in the range of 0.002-5.0 μmol L(-1) (R>0.997) for two aldehydes, the detection limits (SN(-1)=3) were 0.5 nmol L(-1) for hexanal and 0.4 nmol L(-1) for heptanal. The relative standard deviations (RSDs, n=5) of the method were below 7.9% and the recoveries were above 72.7% for the spiked serum. All these results hint that the proposed method is potential for disease markers analysis in complex biological samples. PMID:22483210

  10. Polydimethylsiloxane-based permeation passive air sampler. Part I: Calibration constants and their relation to retention indices of the analytes.

    PubMed

    Seethapathy, Suresh; Górecki, Tadeusz

    2011-01-01

    A simple and cost effective permeation passive sampler equipped with a polydimethylsiloxane (PDMS) membrane was designed for the determination of time-weighted average (TWA) concentrations of volatile organic compounds (VOCs) in air. Permeation passive samplers have significant advantages over diffusive passive samplers, including insensitivity to moisture and high face velocities of air across the surface of the sampler. Calibration constants of the sampler towards 41 analytes belonging to alkane, aromatic hydrocarbon, chlorinated hydrocarbon, ester and alcohol groups were determined. The calibration constants allowed for the determination of the permeability of PDMS towards the selected analytes. They ranged from 0.026 cm² min⁻¹ for 1,1-dichloroethylene to 0.605 cm² min⁻¹ for n-octanol. Further, the mechanism of analyte transport across PDMS membranes allowed for the calibration constants of the sampler to be estimated from the linear temperature programmed retention indices (LTPRI) of the analytes, determined using GC columns coated with pure PDMS stationary phases. Statistical analysis using Student's t test indicated that there was no significant difference at the 95% probability level between the experimentally obtained calibration constants and those estimated using LTPRI for most analyte groups studied. This correlation allows the estimation of the calibration constants of compounds not known to be present at the time of sampler deployment, which makes it possible to determine parameters like total petroleum hydrocarbons in the vapor phase. PMID:21112594