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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. 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.

  2. 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

  3. 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

  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. 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

  19. 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…

  20. 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

  1. 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

  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. 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

  4. 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...

  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. 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

  11. 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.

  12. 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

  13. 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

  14. 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.

  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 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

  1. 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

  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. 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

  4. 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

  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. 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

  12. 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.

  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. 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

  17. 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

  18. 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

  19. 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.

  20. 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

  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. 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...

  3. 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.

  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. 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

  12. 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.

  13. 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.

  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. 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.

  16. 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

  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 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

  19. 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

  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. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  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. 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

  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. 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.

  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. 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.

  3. 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

  4. 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

  5. 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

  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. 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

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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

  7. 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

  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. 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

  9. 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

  10. 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

  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. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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

  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. 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

  5. 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

  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. 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

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  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 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

  9. 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.

  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

  11. Method of producing an electronic unit having a polydimethylsiloxane substrate and circuit lines

    DOEpatents

    Davidson, James Courtney; Krulevitch, Peter A.; Maghribi, Mariam N.; Benett, William J.; Hamilton, Julie K.; Tovar, Armando R.

    2012-06-19

    A system of metalization in an integrated polymer microsystem. A flexible polymer substrate is provided and conductive ink is applied to the substrate. In one embodiment the flexible polymer substrate is silicone. In another embodiment the flexible polymer substrate comprises poly(dimethylsiloxane).

  12. Applications of microfluidics and microchip electrophoresis for potential clinical biomarker analysis.

    PubMed

    Pagaduan, Jayson V; Sahore, Vishal; Woolley, Adam T

    2015-09-01

    This article reviews advances over the last five years in microfluidics and microchip-electrophoresis techniques for detection of clinical biomarkers. The variety of advantages of miniaturization compared with conventional benchtop methods for detecting biomarkers has resulted in increased interest in developing cheap, fast, and sensitive techniques. We discuss the development of applications of microfluidics and microchip electrophoresis for analysis of different clinical samples for pathogen identification, personalized medicine, and biomarker detection. We emphasize the advantages of microfluidic techniques over conventional methods, which make them attractive future diagnostic tools. We also discuss the versatility and adaptability of this technology for analysis of a variety of biomarkers, including lipids, small molecules, carbohydrates, nucleic acids, proteins, and cells. Finally, we conclude with a discussion of aspects that need to be improved to move this technology towards routine clinical and point-of-care applications. PMID:25855148

  13. Passively Q-switched microchip lasers based on Yb:YAG/Cr4+:YAG composite crystal

    NASA Astrophysics Data System (ADS)

    Ren, Yingying; Dong, Jun

    2014-02-01

    Efficient passively Q-switched microchip laser based on Yb:YAG/Cr4+:YAG composite crystal has been demonstrated under high brightness single-emitter laser-diode pumping. Maximum average output power of 1.5 W was obtained when the absorbed pump power was 3.65 W, the corresponding optical-to-optical efficiency was over 41%. The slope efficiency was 52.3%. The effect of the cavity length on the performance of Yb:YAG/Cr4+:YAG composite crystal passively Q-switched microchip lasers was investigated. Laser pulses at 1030 nm with pulse width of 466 ps and peak power of 91 kW were achieved with cavity length of 1.7 mm, while laser pulses with pulse width of 665 ps and peak power of 79 kW were obtained with cavity length of 3.7 mm.

  14. Determination of chloride, chlorate and perchlorate by PDMS microchip electrophoresis with indirect amperometric detection.

    PubMed

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

    2008-03-15

    In this work, chloride, chlorate and perchlorate are fast separated on PDMS microchip and detected via in-channel indirect amperometric detection mode. With PDMS/PDMS microchip treated by oxygen plasma, anions chloride (Cl-), chlorate (ClO3-), and perchlorate (ClO4-) are separated within 35s. Some parameters including buffer salt concentration, buffer pH, separation voltage and detection potential are investigated in detail. The separation conditions using 15 mM (pH 6.12) of 2-(N-morpholino)ethanesulfonic acid (MES)+L-histidine (L-His) as running buffer, -2000 V as separation voltage and 0.7 V as detection potential are optimized. Under this condition, the detection limits of Cl-, ClO3-, and ClO4- are 1.9, 3.6, and 2.8 microM, respectively. PMID:18371861

  15. Passively Q-switched Nd:YAG ceramic microchip laser with azimuthally polarized output

    NASA Astrophysics Data System (ADS)

    Li, J.-L.; Lin, D.; Zhong, L.-X.; Ueda, K.; Shirakawa, A.; Musha, M.; Chen, W.-B.

    2009-10-01

    A passively-Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) ceramic microchip laser was demonstrated to emit azimuthally polarized beam bus using a chromium-doped YAG (Cr4+:YAG) crystal as saturable absorber and a multilayer concentric subwavelength grating as polarization-selective output coupler. The laser's output power reached 512 mW with an initial slope efficiency of nearly 60%, and the pulse had 1.15-kW peak power with 40-ns duration and 11-kHz repetition rate at 3.9-W absorbed pump power. The laser beam's polarization degree was 97.6%. The thermal lensing effect in Nd:YAG microchip remained as a problem to be solved.

  16. Sub-nanosecond Yb:KLu(WO4)2 microchip laser.

    PubMed

    Loiko, P; Serres, J M; Mateos, X; Yumashev, K; Yasukevich, A; Petrov, V; Griebner, U; Aguiló, M; Díaz, F

    2016-06-01

    A diode-pumped Yb:KLu(WO4)2 microchip laser passively Q-switched by a Cr4+:YAG saturable absorber generated a maximum average output power of 590 mW at 1031 nm with a slope efficiency of 55%. The pulse characteristics were 690 ps/47.6 μJ at a pulse repetition frequency of 12.4 kHz. The output beam had an excellent circular profile with M2<1.05. Yb:KLu(WO4)2 is very promising for ultrathin sub-ns microchip lasers. PMID:27244429

  17. APPLICATIONS OF MICROFLUIDICS AND MICROCHIP ELECTROPHORESIS FOR POTENTIAL CLINICAL BIOMARKER ANALYSIS

    PubMed Central

    Pagaduan, Jayson V.; Sahore, Vishal; Woolley, Adam T.

    2015-01-01

    This article reviews advances over the last 5 years in microfluidics and microchip electrophoresis techniques for detection of clinical biomarkers. The various advantages of miniaturization compared with conventional benchtop methods for detecting biomarkers have resulted in increased interest in developing cheap, fast, and sensitive platforms. We discuss the development of applications of microfluidics and microchip electrophoresis for analysis of various clinical samples for pathogen identification, personalized medicine, and biomarker detection. We highlight the advantages of microfluidics platforms over conventional methods that make them an attractive future diagnostic tool. We also discuss the versatility and adaptability of this technology for analysis of various biomarkers, including lipids, small molecules, carbohydrates, nucleic acids, proteins and cells. Finally, we conclude with a discussion of areas that need to be improved upon to move this technology towards routine clinical and point-of-care applications. PMID:25855148

  18. Immobilization of DNA in polyacrylamide gel for the manufacture of DNA and DNA-oligonucleotide microchips.

    SciTech Connect

    Proudnikov, D.; Timofeev, E.; Mirzabekov, A.; Center for Mechanistic Biology and Biotechnology; Engelhardt Inst. of Molecular Biology

    1998-05-15

    Activated DNA was immobilized in aldehyde-containing polyacrylamide gel for use in manufacturing the MAGIChip (microarrays of gel-immobilized compounds on a chip). First, abasic sites were generated in DNA by partial acidic depurination. Amino groups were then introduced into the abasic sites by reaction with ethylenediamine and reduction of the aldimine bonds formed. It was found that DNA could be fragmented at the site of amino group incorporation or preserved mostly unfragmented. In similar reactions, both amino-DNA and amino-oligonucleotides were attached through their amines to polyacrylamide gel derivatized with aldehyde groups. Single- and double-stranded DNA of 40 to 972 nucleotides or base pairs were immobilized on the gel pads to manufacture a DNA microchip. The microchip was hybridized with fluorescently labeled DNA-specific oligonucleotide probes. This procedure for immobilization of amino compounds was used to manufacture MAGIChips containing both DNA and oligonucleotides.

  19. Hyperbranched fluoropolymer-polydimethylsiloxane-poly(ethylene glycol) cross-linked terpolymer networks designed for marine and biomedical applications: heterogeneous nontoxic antibiofouling surfaces.

    PubMed

    Pollack, Kevin A; Imbesi, Philip M; Raymond, Jeffery E; Wooley, Karen L

    2014-01-01

    Synthesis of terpolymer coatings composed of hyperbranched fluoropolymers cross-linked with bisamino-propyl poly(ethylene glycol) and bisamino-propyl polydimethylsiloxane (PDMS) was performed to generate antibiofouling surfaces. Nanoscale imaging and surface spectroscopy confirmed that this system possessed complex surface topographies and chemical compositions. Surface complexity was determined to be due to molecular interactions, phase segregation, and compositional gradients arising between the three components. A clear difference in surface behavior was observable before and after exposure to water. Antibiofouling characteristics were investigated by bovine serum albumin (BSA) adsorption studies; the terpolymer coating displayed a 60% greater resistance to protein adsorption in comparison to the fouling of a commercial antibiofouling silicone coating. The unique surface topography, topology, and chemical heterogeneity expressed at a variety of scales provide a robust regime for the generation of hardy, complex surfaces known to incorporate characteristics appropriate for antibiofouling applications. Thorough assessment of thermal responses and mechanical properties in relevant environments demonstrated a formulation platform immediately appropriate for consideration in marine and in vivo applications. PMID:25329934

  20. [Microchip-based reversed-phase liquid chromatography-tandem mass spectrometry platform for protein analysis].

    PubMed

    Liang, Yu; Wu, Ci; Dai, Zhongpeng; Liang, Zuocheng; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

    2011-06-01

    Due to the high throughput and high sensitivity, the hyphenation of microchip-based high performance liquid chromatography with tandem mass spectrometry has been paid much attention. In our recent work, with poly (lauryl methacrylate-co-trimethylolpropane trimethacrylate) monolithic materials prepared in microchannels as trap and separation columns, conventional micro-liquid chromatography pumps and valves for fluidic control, and a small-bore open-tube capillary attached to the outlet channel as chip-mass spectrometer (MS) interface, the microchip-based reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) platform was established, and applied for the identification of proteins. By such platform, 100 ng digest of bovine serum albumin (BSA) was successfully analyzed with the sequence coverages as 39.37%, 37.89% and 34.10% (with the relative standard deviation (RSD) of 7.3%) in three runs, separately. To evaluate the chip-to-chip reproducibility, BSA was identified by such platform with the microchips from different batches containing trap column, separation column and chip-MS interface. The obtained sequence coverage and the number of peptides identified were comparable. All these results showed high sensitivity and good reproducibility of such platform, demonstrating the great potential for rapid protein analysis. PMID:22032155

  1. Microchip electrophoresis with electrochemical detection for the determination of analytes in the dopamine metabolic pathway

    PubMed Central

    Saylor, Rachel A.; Reid, Erin A.; Lunte, Susan M.

    2016-01-01

    A method for the separation and detection of analytes in the dopamine metabolic pathway was developed using microchip electrophoresis with electrochemical detection. The microchip consisted of a 5 cm PDMS separation channel in a simple-t configuration. Analytes in the dopamine metabolic pathway were separated using a background electrolyte composed of 15 mM phosphate at pH 7.4, 15 mM SDS, and 2.5 mM boric acid. Two different microchip substrates using different electrode materials were compared for the analysis: a PDMS/PDMS device with a carbon fiber electrode and a PDMS/glass hybrid device with a pyrolyzed photoresist film carbon electrode. While the PDMS/PDMS device generated high separation efficiencies and good resolution, more reproducible migration times were obtained with the PDMS/glass hybrid device, making it a better choice for biological applications. Lastly, the optimized method was used to monitor L-DOPA metabolism in a rat brain slice. PMID:25958983

  2. Improving chip-to-chip precision in disposable microchip capillary electrophoresis devices with internal standards.

    PubMed

    Bidulock, Allison C E; van den Berg, Albert; Eijkel, Jan C T

    2015-03-01

    To realize portable systems for routine measurements in point-of-care settings, MCE methods are required to be robust across many single-use chips. While it is well-known internal standards (ISTDs) improve run-to-run precision, a systematic investigation is necessary to determine the significance of chip-to-chip imprecision in MCE and how ISTDs account for it. This paper addresses this question by exploring the reproducibility of Na quantification across six basic, in-house fabricated microchips. A dataset of 900 electrophoerograms was collected from analyzing five concentrations of NaCl with two ISTDs (CsCl and LiCl). While both improved the peak area reproducibility, the Na/Cs ratio was superior to the Na/Li ratio (improving the RSD by a factor of 2-4, depending on the Na concentration). We attribute this to the significant variation in microchannel surface properties, which was accounted for by cesium but not lithium. Microchip dimension and detector variations were only a few percent, and could be improved through commercial fabrication over in-house made microchips. These results demonstrate that ISTDs not only correct for intrachip imprecision, but are also a viable means to correct for chip-to-chip imprecision inherent in disposable, point-of-care MCE devices. However, as expected, the internal standard must be carefully chosen. PMID:25522336

  3. Microchip electrophoresis with electrochemical detection for the determination of analytes in the dopamine metabolic pathway.

    PubMed

    Saylor, Rachel A; Reid, Erin A; Lunte, Susan M

    2015-08-01

    A method for the separation and detection of analytes in the dopamine metabolic pathway was developed using microchip electrophoresis with electrochemical detection. The microchip consisted of a 5 cm PDMS separation channel in a simple-t configuration. Analytes in the dopamine metabolic pathway were separated using a background electrolyte composed of 15 mM phosphate at pH 7.4, 15 mM SDS, and 2.5 mM boric acid. Two different microchip substrates using different electrode materials were compared for the analysis: a PDMS/PDMS device with a carbon fiber electrode and a PDMS/glass hybrid device with a pyrolyzed photoresist film carbon electrode. While the PDMS/PDMS device generated high separation efficiencies and good resolution, more reproducible migration times were obtained with the PDMS/glass hybrid device, making it a better choice for biological applications. Lastly, the optimized method was used to monitor l-DOPA metabolism in a rat brain slice. PMID:25958983

  4. Ultra-fast simultaneous detection of obesity-related coenzymes in mice using microchip electrophoresis with a LIF detector.

    PubMed

    Lee, Hee Gu; Kumar, K S; Soh, Ju-Ryoun; Cha, Youn-Soo; Kang, Seong Ho

    2008-06-30

    Hepatic acyl-coenzyme A synthetase (ACS), carnitine palmitoyltransferase-I (CPT-I) and acetyl coenzyme A carboxylase (ACC) are coenzymes associated with the genetic type of obesity in animal models. This paper reports the use of microchip electrophoresis (ME) with a laser-induced fluorescence (LIF) detector based on a reverse transcriptase-polymerase chain reaction (RT-PCR) to detect the amplified DNA fragments of these coenzymes (ACS, CPT-I and ACC) in the mRNA extracted from mice. DNA fragments ranging from 50 to 2652 bp were well resolved using this procedure with a running buffer (1x TBE), 0.5% polyvinylpyrrolidone (M(r) 1,000,000) as the coating gel and 0.7% polyethyleneoxide (M(r) 8,000,000) as the sieving gel at pH 8.30. The separation of the three RT-PCR products was achieved by ME in a single-run within 17 s using programmed field strength gradients (PFSG) (470 V cm(-1) for 9 s, 205.8 V cm(-1) for 2 s, 411.6 V cm(-1) for 4 s, 117.6 V cm(-1) for 2 s and 470.4V cm(-1) for 8 s). The ME-PFSG method was found to be 4 times faster than the method using a constant field and 138 times faster than slab gel electrophoresis. Moreover, the amplified RT-PCR products of the obesity-related coenzymes in C57BL/6J mice were analyzed using only sub-micro liter samples. PMID:18539180

  5. A modified electrode for the electrochemical detection of biogenic amines and their amino acid precursors separated by microchip capillary electrophoresis.

    PubMed

    Dossi, Nicolò; Toniolo, Rosanna; Pizzariello, Andrea; Susmel, Sabina; Bontempelli, Gino

    2011-04-01

    The use of a mixed-valent ruthenium oxide/hexacyanoruthenate polymeric film electrochemically deposited onto glassy carbon electrodes is proposed here for the detection of biogenic amines and their amino acid precursors, following their separation by microchip capillary electrophoresis. The ability of this ruthenium coating to electrocatalyze the oxidation of aliphatic and heterocyclic amines, as well as their amino acid precursors, was checked by using ethanolamine, tryptamine and tryptophane as prototype compounds and adopting a 25 mM sulphuric acid as the electrolyte in the detection cell, where a constant potential of 1.05 V versus Ag/AgCl, 3 M KCl was applied to the modified working electrode. Optimization of parameters affecting both detection and separation steps led to satisfactory separations when performed by using a 20 mM phosphate running buffer (pH 2.5) and applying a high voltage of 2.5 kV both in the separation and in the electrokinetic injection (duration 4 s). The recorded peaks were characterized by good repeatability (RSD ≤ 3.6%), high sensitivity and a wide linear range. Detection limits of 23 μM (1.4 mg/L), 27 μM (4.3 mg/L) and 34 μM (6.8 mg/L) were inferred for ethanolamine, tryptamine and tryptophane, respectively. The approach proposed here was also applied for the analysis of some double malt dark beers spiked with a controlled amount of the analytes considered. PMID:21437919

  6. Microchip electrophoresis with background electrolyte containing polyacrylic acid and high content organic solvent in cyclic olefin copolymer microchips for easily adsorbed dyes.

    PubMed

    Wei, Xuan; Sun, Ping; Yang, Shenghong; Zhao, Lei; Wu, Jing; Li, Fengyun; Pu, Qiaosheng

    2016-07-29

    Plastic microchips can significantly reduce the fabrication cost but the adsorption of some analytes limits their application. In this work, background electrolyte containing ionic polymer and high content of organic solvent was adopted to eliminate the analyte adsorption and achieve highly efficient separation in microchip electrophoresis. Two dyes, rhodamine 6G (Rh6G) and rhodamine B (RhB) were used as the model analytes. By using methanol as the organic solvent and polyacrylic acid (PAA) as a multifunctional additive, successful separation of the two dyes within 75μm id. microchannels was realized. The role of PAA is multiple, including viscosity regulator, selectivity modifier and active additive for counteracting analyte adsorption on the microchannel surface. The number of theoretical plate of 7.0×10(5)/m was attained within an effective separation distance of 2cm using background electrolyte consisting 80% methanol, 0.36% PAA and 30mmol/L phosphate at pH 5.0. Under optimized conditions, relative standard deviations of Rh6G and RhB detection (n=5) were no more than 1.5% for migration time and 2.0% for peak area, respectively. The limit of detection (S/N=3) was 0.1nmol/L for Rh6G. The proposed technique was applied in the determination of both Rh6G and RhB in chilli powder and lipstick samples with satisfactory recoveries of 81.3-103.7%. PMID:27371017

  7. Effect of repeated contact on adhesion measurements involving polydimethylsiloxane structural material

    NASA Astrophysics Data System (ADS)

    Kroner, E.; Maboudian, R.; Arzt, E.

    2009-09-01

    During the last few years several research groups have focused on the fabrication of artificial gecko inspired adhesives. For mimicking these structures, different polymers are used as structure material, such as polydimethylsiloxanes (PDMS), polyurethanes (PU), and polypropylene (PP). While these polymers can be structured easily and used for artificial adhesion systems, the effects of repeated adhesion testing have never been investigated closely. In this paper we report on the effect of repeated adhesion measurements on the commercially available poly(dimethylsiloxane) polymer kit Sylgard 184 (Dow Corning). We show that the adhesion force decreases as a function of contact cycles. The rate of change and the final value of adhesion are found to depend on the details of the PDMS synthesis and structuring.

  8. Compaction of poly(dimethylsiloxane) (PDMS) due to proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Szilasi, Szabolcs Zoltan; Kokavecz, Janos; Huszank, Robert; Rajta, Istvan

    2011-03-01

    This work is about the detailed investigation of the changes of the surface topography, the degree of compaction/shrinkage and its relation to the irradiation fluence and the structure spacing in poly(dimethylsiloxane) (PDMS) patterned with 2 MeV proton microbeam. The irradiated periodic structures consisted of parallel lines with different widths and spacing. To achieve different degrees of compaction, each structure was irradiated with more different fluences. At the irradiated areas the surface topography, the adhesion, the wettability and the rigidity of the surface also changes due to the chemical/structural change of the basic poly(dimethylsiloxane) polymer. The surface topography, the phase modification of the surface, and the connection between them was revealed with using an atomic force microscope (AFM).

  9. Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite

    PubMed Central

    Shih, Wen-Pin; Tsao, Li-Chi; Lee, Chian-Wen; Cheng, Ming-Yuan; Chang, Chienliu; Yang, Yao-Joe; Fan, Kuang-Chao

    2010-01-01

    This paper presents a novel method to fabricate temperature sensor arrays by dispensing a graphite-polydimethylsiloxane composite on flexible polyimide films. The fabricated temperature sensor array has 64 sensing cells in a 4 × 4 cm2 area. The sensor array can be used as humanoid artificial skin for sensation system of robots. Interdigitated copper electrodes were patterned on the flexible polyimide substrate for determining the resistivity change of the composites subjected to ambient temperature variations. Polydimethylsiloxane was used as the matrix. Composites of different graphite volume fractions for large dynamic range from 30 °C to 110 °C have been investigated. Our experiments showed that graphite powder provided the composite high temperature sensitivity. The fabricated temperature sensor array has been tested. The detected temperature contours are in good agreement with the shapes and magnitudes of different heat sources. PMID:22319314

  10. Plasma-induced surface modification of polydimethylsiloxane aimed at reducing salt and protein deposition.

    PubMed

    De Smet, Nele; Rymarczyk-Machal, Monika; Schacht, Etienne

    2011-01-01

    Polydimethylsiloxane (PDMS) is an elastomer that is widely used in construction and for biological and biomedical applications. The biocompatibility of PDMS was improved by different surface treatment methods, i.e., plasma treatment or a combination of plasma treatment with UV-irradiation or redox initiator, to minimize the effects of deposition of salts and proteins. In this work we used the vinyl monomers sulfobetaine and AMPS which have good biocompatible properties. PMID:21176391

  11. Ultrasensitive microchip sensor based on boron-containing polyfluorene nanofilms.

    PubMed

    Ribeiro, Celso; Brogueira, Pedro; Lavareda, Guilherme; Carvalho, Carlos N; Amaral, Ana; Santos, Luís; Morgado, Jorge; Scherf, Ulrich; Bonifácio, Vasco D B

    2010-12-15

    A fluorene-based π-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. PMID:20943367

  12. Printed Flexible Plastic Microchip for Viral Load Measurement through Quantitative Detection of Viruses in Plasma and Saliva

    PubMed Central

    Shafiee, Hadi; Kanakasabapathy, Manoj Kumar; Juillard, Franceline; Keser, Mert; Sadasivam, Magesh; Yuksekkaya, Mehmet; Hanhauser, Emily; Henrich, Timothy J.; Kuritzkes, Daniel R.; Kaye, Kenneth M.; Demirci, Utkan

    2015-01-01

    We report a biosensing platform for viral load measurement through electrical sensing of viruses on a flexible plastic microchip with printed electrodes. Point-of-care (POC) viral load measurement is of paramount importance with significant impact on a broad range of applications, including infectious disease diagnostics and treatment monitoring specifically in resource-constrained settings. Here, we present a broadly applicable and inexpensive biosensing technology for accurate quantification of bioagents, including viruses in biological samples, such as plasma and artificial saliva, at clinically relevant concentrations. Our microchip fabrication is simple and mass-producible as we print microelectrodes on flexible plastic substrates using conductive inks. We evaluated the microchip technology by detecting and quantifying multiple Human Immunodeficiency Virus (HIV) subtypes (A, B, C, D, E, G, and panel), Epstein-Barr Virus (EBV), and Kaposi’s Sarcoma-associated Herpes Virus (KSHV) in a fingerprick volume (50 µL) of PBS, plasma, and artificial saliva samples for a broad range of virus concentrations between 102 copies/mL and 107 copies/mL. We have also evaluated the microchip platform with discarded, de-identified HIV-infected patient samples by comparing our microchip viral load measurement results with reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) as the gold standard method using Bland-Altman Analysis. PMID:26046668

  13. Printed Flexible Plastic Microchip for Viral Load Measurement through Quantitative Detection of Viruses in Plasma and Saliva.

    PubMed

    Shafiee, Hadi; Kanakasabapathy, Manoj Kumar; Juillard, Franceline; Keser, Mert; Sadasivam, Magesh; Yuksekkaya, Mehmet; Hanhauser, Emily; Henrich, Timothy J; Kuritzkes, Daniel R; Kaye, Kenneth M; Demirci, Utkan

    2015-01-01

    We report a biosensing platform for viral load measurement through electrical sensing of viruses on a flexible plastic microchip with printed electrodes. Point-of-care (POC) viral load measurement is of paramount importance with significant impact on a broad range of applications, including infectious disease diagnostics and treatment monitoring specifically in resource-constrained settings. Here, we present a broadly applicable and inexpensive biosensing technology for accurate quantification of bioagents, including viruses in biological samples, such as plasma and artificial saliva, at clinically relevant concentrations. Our microchip fabrication is simple and mass-producible as we print microelectrodes on flexible plastic substrates using conductive inks. We evaluated the microchip technology by detecting and quantifying multiple Human Immunodeficiency Virus (HIV) subtypes (A, B, C, D, E, G, and panel), Epstein-Barr Virus (EBV), and Kaposi's Sarcoma-associated Herpes Virus (KSHV) in a fingerprick volume (50 µL) of PBS, plasma, and artificial saliva samples for a broad range of virus concentrations between 10(2) copies/mL and 10(7) copies/mL. We have also evaluated the microchip platform with discarded, de-identified HIV-infected patient samples by comparing our microchip viral load measurement results with reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) as the gold standard method using Bland-Altman Analysis. PMID:26046668

  14. Laser-generated ultrasound with optical fibres using functionalised carbon nanotube composite coatings

    NASA Astrophysics Data System (ADS)

    Colchester, Richard J.; Mosse, Charles A.; Bhachu, Davinder S.; Bear, Joseph C.; Carmalt, Claire J.; Parkin, Ivan P.; Treeby, Bradley E.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2014-04-01

    Optical ultrasound transducers were created by coating optical fibres with a composite of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). Dissolution of CNTs in PDMS to create the composite was facilitated by functionalisation with oleylamine. Composite surfaces were applied to optical fibres using dip coating. Under pulsed laser excitation, ultrasound pressures of 3.6 MPa and 4.5 MPa at the coated end faces were achieved with optical fibre core diameters of 105 and 200 μm, respectively. The results indicate that CNT-PDMS composite coatings on optical fibres could be viable alternatives to electrical ultrasound transducers in miniature ultrasound imaging probes.

  15. Antimicrobial Activity Evaluation on Silver Doped Hydroxyapatite/Polydimethylsiloxane Composite Layer.

    PubMed

    Ciobanu, C S; Groza, A; Iconaru, S L; Popa, C L; Chapon, P; Chifiriuc, M C; Hristu, R; Stanciu, G A; Negrila, C C; Ghita, R V; Ganciu, M; Predoi, D

    2015-01-01

    The goal of this study was the preparation, physicochemical characterization, and microbiological evaluation of novel hydroxyapatite doped with silver/polydimethylsiloxane (Ag:HAp-PDMS) composite layers. In the first stage, the deposition of polydimethylsiloxane (PDMS) polymer layer on commercially pure Si disks has been produced in atmospheric pressure corona discharges. Finally, the new silver doped hydroxyapatite/polydimethylsiloxane composite layer has been obtained by the thermal evaporation technique. The Ag:HAp-PDMS composite layers were characterized by various techniques, such as Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The antimicrobial activity of the Ag:HAp-PDMS composite layer was assessed against Candida albicans ATCC 10231 (ATCC-American Type Culture Collection) by culture based and confirmed by SEM and Confocal Laser Scanning Microscopy (CLSM) methods. This is the first study reporting the antimicrobial effect of the Ag:HAp-PDMS composite layer, which proved to be active against Candida albicans biofilm embedded cells. PMID:26504849

  16. Antimicrobial Activity Evaluation on Silver Doped Hydroxyapatite/Polydimethylsiloxane Composite Layer

    PubMed Central

    Ciobanu, C. S.; Groza, A.; Iconaru, S. L.; Popa, C. L.; Chapon, P.; Chifiriuc, M. C.; Hristu, R.; Stanciu, G. A.; Negrila, C. C.; Ghita, R. V.; Ganciu, M.; Predoi, D.

    2015-01-01

    The goal of this study was the preparation, physicochemical characterization, and microbiological evaluation of novel hydroxyapatite doped with silver/polydimethylsiloxane (Ag:HAp-PDMS) composite layers. In the first stage, the deposition of polydimethylsiloxane (PDMS) polymer layer on commercially pure Si disks has been produced in atmospheric pressure corona discharges. Finally, the new silver doped hydroxyapatite/polydimethylsiloxane composite layer has been obtained by the thermal evaporation technique. The Ag:HAp-PDMS composite layers were characterized by various techniques, such as Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The antimicrobial activity of the Ag:HAp-PDMS composite layer was assessed against Candida albicans ATCC 10231 (ATCC—American Type Culture Collection) by culture based and confirmed by SEM and Confocal Laser Scanning Microscopy (CLSM) methods. This is the first study reporting the antimicrobial effect of the Ag:HAp-PDMS composite layer, which proved to be active against Candida albicans biofilm embedded cells. PMID:26504849

  17. Raman imaging spectroscopic characterization of modified poly(dimethylsiloxane) for micro total analysis systems applications

    NASA Astrophysics Data System (ADS)

    de Campos, Richard Piffer Soares; Yoshida, Inez Valeria Pagotto; Breitkreitz, Márcia Cristina; Poppi, Ronei Jesus; Fracassi da Silva, José Alberto

    Methacryloxypropyl-modified poly(dimethylsiloxane) rubbers were obtained from poly(dimethylsiloxane), PDMS, and methacryloxypropyltrimethoxysilane, MPTMS, by polycondensation reactions. The modified rubbers, prepared with 20 and 30% (v/v) of MPTMS, were used as substrates for microchannel fabrication by the CO2 laser ablation technique. Raman imaging spectroscopy was used for the surface characterization, showing the homogeneity of the rubbery material, with uniform distribution of the crosslinking centers. Under the experimental conditions used, damage to the rubber from the CO2 laser radiation used for the channel engraving was not observed. Correlation maps of the surface were obtained in order to spatially evaluate the modification inside and outside the channels. The correlations between the methacryloxypropyl-modified poly(dimethylsiloxane) rubbers and MPTMS (spectral range of 1800-1550 cm-1) and PDMS (spectral range of 820-670 cm-1) precursors were higher than 0.95 and 0.99, respectively. In addition, Raman imaging spectroscopy allows monitoring the topography of the fabricated microchannel.

  18. A norepinephrine coated magnetic molecularly imprinted polymer for simultaneous multiple chiral recognition.

    PubMed

    Chen, Juan; Liang, Ru-Ping; Wang, Xiao-Ni; Qiu, Jian-Ding

    2015-08-28

    A newly designed molecularly imprinted polymer (MIP) material was developed and successfully used as recognition element for enantioselective recognition by microchip electrophoresis. In this work, molecularly imprinted polymers were facilely prepared employing Fe3O4 nanoparticles (NPs) as the supporting substrate and norepinephrine as the functional monomer in the presence of template molecule in a weak alkaline solution. After extracting the embedded template molecules, the produced imprinted Fe3O4@polynorepinephrine (MIP-Fe3O4@PNE) NPs have cavities complementary to three dimensional shape of template molecules favoring high binding capacity and magnetism property for easy manipulation. The MIP-Fe3O4@PNE NPs prepared with l-tryptophan, l-valine, l-threonine, Gly-l-Phe, S-(-)-ofloxacin or S-(-)-binaphthol as template molecules were packed in the polydimethylsiloxane microchannel via magnetic field as novel stationary phase to successful enantioseparation of corresponding target analysts. The MIP-Fe3O4@PNE NPs-based microchip electrophoresis system exhibited strong recognition ability, excellent high-performance, admirable reproducibility and stability, which provided a powerful protocol for separation enantiomers within a short analytical time and opened up an avenue for multiplex chiral compound assay in various systems. PMID:26206627

  19. One-step surface modification for irreversible bonding of various plastics with a poly(dimethylsiloxane) elastomer at room temperature.

    PubMed

    Wu, Jing; Lee, Nae Yoon

    2014-05-01

    Here, we introduce a simple and facile method for bonding poly(dimethylsiloxane) (PDMS) to various plastics irreversibly via a one-step chemical treatment at room temperature. This was mediated by poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] (amine-PDMS linker), a chemical composed of a PDMS backbone incorporating an amine side group. Room temperature anchoring of the linker was achieved via a reaction between the amine functionality of the linker and the carbon backbone of the plastics, thereby producing urethane bonds. This resulted in the PDMS functionality being exposed on the plastic surface, mimicking the surface properties of bulk PDMS. Following corona treatment of the PDMS-modified plastic and a sheet of PDMS, the two surfaces were placed in contact with each other and heated at 80 °C for 1 h. This resulted in permanent bonding between PDMS and the plastic. To examine the effectiveness of the amine-PDMS linker coating procedure, the surfaces were characterized by measuring water contact angles and by employing X-ray photoelectron spectroscopy (XPS). Polycarbonate (PC), poly(ethylene terephthalate) (PET), poly(vinylchloride) (PVC), and polyimide (PI) were bonded successfully to PDMS using this method, with bond strengths of PC, PET, and PVC with PDMS measured to be approximately 428.5 ± 17.9, 361.7 ± 31.2, and 430.0 ± 14.9 kPa, respectively. The bond strength of a PC-PC homogeneous assembly, also realized using the proposed method, was measured to be approximately 343.9 ± 7.4 kPa. Delamination tests revealed that the PC-PC assembly was able to withstand intense introduction of a liquid whose per-minute injection volume was approximately 278 times greater than the total internal volume of the microchannel fabricated in PC. This demonstrated the robustness of the seal formed using the proposed technique. PMID:24632757

  20. A biocompatible microchip and methodology for efficiently trapping and positioning living cells into array based on negative dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoliang; Zhu, Rong

    2015-06-01

    We present a microchip and trapping methodology based on negative dielectrophoresis (nDEP), whereby living cells were manipulated and positioned into an array with high trapping efficiency while maintaining good viability. The main factors that ensured good viability of cells were investigated including temperature of medium, extra transmembrane potential on cells, and electrolysis effect in DEP-based trapping. Optimum DEP conditions for the microchip were determined by considering both biocompatibility and trapping efficiency. Experiments demonstrated that under a voltage of 3.6-4 Vpp and at a frequency of 100 kHz, HeLa cells could be trapped and positioned into an array in less than 10 s while maintaining good viability. The normal adherence morphology and fluorescence of the cells, dyed with propidium iodide and Calcein-AM, were observed and verified the biocompatibility of the microchip and trapping methodology.

  1. Feasibility of capillary liquid chromatography/microchip atmospheric pressure photoionization mass spectrometry in analyzing anabolic steroids in urine samples.

    PubMed

    Ahonen, Linda L; Haapala, Markus; Saarela, Ville; Franssila, Sami; Kotiaho, Tapio; Kostiainen, Risto

    2010-04-15

    We examined the feasibility of capillary liquid chromatography/microchip atmospheric pressure photoionization tandem mass spectrometry (capLC/microAPPI-MS/MS) for the analysis of anabolic steroids in human urine. The urine samples were pretreated by enzymatic hydrolysis (with beta-glucuronidase from Helix pomatia), and the compounds were liquid-liquid extracted with diethyl ether. After separation the compounds were vaporized by microchip APPI, photoionized by a 10 eV krypton discharge lamp, and detected by selected reaction monitoring. The capLC/microAPPI-MS/MS method showed good sensitivity with detection limits at the level of 1.0 ng mL(-1), good linearity with correlation coefficients between 0.9954 and 0.9990, and good repeatability with relative standard deviations below 10%. These results demonstrate that microchip APPI combined with capLC/MS/MS provides a new potential method for analyzing non-polar and neutral compounds in biological samples. PMID:20209666

  2. Photoinduced absorption measurement on a microchip equipped with organic dye-doped polymer waveguide

    NASA Astrophysics Data System (ADS)

    Kawaguchi, T.; Nagai, K.; Yamashita, K.

    2013-05-01

    We have fabricated a waveguide-type optical sensing microchip and succeeded in on-chip photoinduced absorption (PIA) spectroscopy. The PIA microchip was fabricated with a conventional photolithographic technique and consisted of plastic optical waveguides and microfluidic channels. Furthermore, a serially-cascaded polymer waveguide doped with organic dyes was integrated on this microchip, which was fabricated using a self-written waveguide process. This dye-doped waveguide was pumped by a UV light emitting diode (UV-LED) and used as a probe light source with a broad emission spectrum. At the same time, a solution of test material in the microfluidic channel was synchronously pumped by a UV-LED or UV laser diode. Since the transmission spectrum of the photo-excited test material could be measured, the PIA spectra were obtained easily. In this study, we have demonstrated the on-chip PIA measurements for two classes of test materials, rare-earth complex and chlorophyll molecules. In the measurement for the aqueous solution of Neodymium (III) acetate hydrate, PIA signals attributed to the 4f-4f transition was observed. Furthermore, by varying the modulation frequency of the pulsed optical pumping, lifetime analysis of the excited 4f states was achieved. In the measurements for the ethanol solutions of chlorophyll a and chlorophyll b, PIA signals were observed at the wavelength near the Q-band absorption peaks. These spectra were very similar to the well-known feature for the photosystem II protein complex observed in a conventional PIA system. From these results, it is expected that the onchip PIA measurement technique is applicable to the transient analyses for the material systems with photoexcited charge transfer.

  3. Use of epoxy-embedded electrodes to integrate electrochemical detection with microchip-based analysis systems

    PubMed Central

    Selimovic, Asmira; Johnson, Alicia S.; Kiss, István Z.; Martin, R. Scott

    2011-01-01

    A new method of fabricating electrodes for microchip devices that involves the use of Teflon molds and a commercially available epoxy to embed electrodes of various size and composition is described. The resulting epoxy base can be polished to generate a fresh electrode and sealed against PDMS-based fluidic structures. Microchip-based flow injection analysis was used to characterize the epoxy-embedded electrodes. It was shown that gold electrodes can be amalgamated with liquid mercury and the resulting mercury/gold electrode used to selectively detect glutathione from lysed red blood cells. The ability to encapsulate multiple electrode materials of differing composition enabled the integration of microchip electrophoresis with electrochemical detection. Finally, a unique feature of this approach is that the electrode connection is made from the bottom of the epoxy base. This enables the creation of three-dimensional gold pillar electrodes (65 µm in diameter and 27 µm in height) that can be integrated within a fluidic network. As compared to the use of a flat electrode of a similar diameter, the use of the pillar electrode led to improvements in both the sensitivity (72.1 pA/µM for the pillar vs. 4.2 pA/µM for the flat electrode) and limit of detection (20 nM for the pillar vs. 600 nM for the flat electrode), with catechol being the test analyte. These epoxy-embedded electrodes hold promise for the creation of inexpensive microfluidic devices that can be used to electrochemically detect biologically important analytes in a manner where the electrodes can be polished and a fresh electrode surface generated as desired. PMID:21413031

  4. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    NASA Astrophysics Data System (ADS)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  5. Separation of motile sperm for in vitro fertilization from frozen-thawed bull semen using progesterone induction on a microchip.

    PubMed

    Li, Jingchun; Ning, Bolin; Cao, Xinyan; Luo, Yinghua; Guo, Li; Wei, Guosheng; Liu, Shengjun; Zhang, Ying; Zhang, Aizhong; Wu, Rui; Li, Yanbing

    2016-09-01

    This study presents a novel method for the separation of motile sperm from non-progressive motile and immotile sperm and in vitro Fertilization (IVF). This separation of bull sperm was accomplished by inducing chemotaxis along a progesterone release agent in a 7.5-mm microchannel microchip composed of a biocompatible polydimethysiloxane layer and a glass gradient. The selected sperm was applied directly for IVF. In the first experiment, we tested the effect of different lengths of microchannnel (5mm, 7.5mm and 10mm) on quality parameter of separated sperm. The results showed that separated sperm using 7.5-mm microchannel chip were improved in sperm motility, swimming velocity, and beat frequency compared with other groups. In the second experiment, a medium containing sperm from swim-up method and outlet reservoir of our 7.5-mm microchannel chip was collected and mitochondrial activity of the sperm was determined by fluorescence microscopy. The sperm from the microchip had higher mitochondria activity (47.6%±6.0%) than the sperm from the swim-up method (23.6%±4.7%) (P<0.05). There were significant differences in rate of acrosome intactness between the swim-up method and the microchip (36.0%±4.1% vs. 66.8±2.1%, respectively, P<0.05). In the third experiment, we compared sperm penetration in the microchip-IVF system with a standard IVF method (droplet-IVF). The microchip-IVF group had the highest percentages of oocytes penetrated (82.2%±1.6% vs. 63.5%±2.4%) and monospermic oocytes (67.8%±3.4% vs. 42.4%±1.5%). In addition, early developmental competence of oocytes to the blastocyst stage was higher when the oocytes were inseminated in the microchip-IVF system compared with those inseminated in a standard droplet-IVF system. These results demonstrate that our microchip based on a sperm chemotaxis system is useful for motile sperm separation from frozen-thawed bull semen for IVF. Therefore, the optimized microchip system provides a good opportunity to sort

  6. Assessment of adulteration of soybean proteins in dairy products by 2D microchip-CE device.

    PubMed

    Wu, Ruige; Wang, Zhiping; Fung, Ying Sing; Seah, Daphne Yen Peng; Yeung, William Shu-Biu

    2014-06-01

    To determine the adulteration of soybean proteins in dairy product, a microchip-CE device was developed to isolate selected fraction of soybean and milk proteins in pI range from 5.5 ∼ 7.0 by 1D IEF, followed by ITP/CZE in the embedded capillary for preconcentration, separation and UV detection at 280 nm. Compared to IEF-CZE without ITP preconcentration, the enhancement factor (EF) in detection of soybean proteins was 20 times. Adulteration of 0.1% soybean protein in total dairy proteins can be detected in less than 10 min. PMID:25025095

  7. Analysis of explosives via microchip electrophoresis and conventional capillary electrophoresis: a review.

    PubMed

    Pumera, Martin

    2006-01-01

    The upsurge in terrorist activity has generated tremendous demand for innovative tools capable of detecting major industrial, military, and home-made (improvised) explosives. Fast, sensitive, and reliable detection of explosives in the field is a very important issue in nowadays. CE, especially in its miniaturized format (lab-on-a-chip), offers great possibilities to create portable, field deployable, rapidly responding, and potentially disposable devices, allowing security forces to make the important decisions regarding the safety of civilians. This article overviews the microchip and conventional capillary electrophoretic techniques for analysis of a wide variety of explosive compounds and mixtures. PMID:16307431

  8. Multichannel microchip electrophoresis device fabricated in polycarbonate with an integrated contact conductivity sensor array.

    PubMed

    Shadpour, Hamed; Hupert, Mateusz L; Patterson, Donald; Liu, Changgeng; Galloway, Michelle; Stryjewski, Wieslaw; Goettert, Jost; Soper, Steven A

    2007-02-01

    A 16-channel microfluidic chip with an integrated contact conductivity sensor array is presented. The microfluidic network consisted of 16 separation channels that were hot-embossed into polycarbonate (PC) using a high-precision micromilled metal master. All channels were 40 microm deep and 60 microm wide with an effective separation length of 40 mm. A gold (Au) sensor array was lithographically patterned onto a PC cover plate and assembled to the fluidic chip via thermal bonding in such a way that a pair of Au microelectrodes (60 microm wide with a 5 microm spacing) was incorporated into each of the 16 channels and served as independent contact conductivity detectors. The spacing between the corresponding fluidic reservoirs for each separation channel was set to 9 mm, which allowed for loading samples and buffers to all 40 reservoirs situated on the microchip in only five pipetting steps using an 8-channel pipettor. A printed circuit board (PCB) with platinum (Pt) wires was used to distribute the electrophoresis high-voltage to all reservoirs situated on the fluidic chip. Another PCB was used for collecting the conductivity signals from the patterned Au microelectrodes. The device performance was evaluated using microchip capillary zone electrophoresis (mu-CZE) of amino acid, peptide, and protein mixtures as well as oligonucleotides that were separated via microchip capillary electrochromatography (mu-CEC). The separations were performed with an electric field (E) of 90 V/cm and were completed in less than 4 min in all cases. The conductivity detection was carried out using a bipolar pulse voltage waveform with a pulse amplitude of +/-0.6 V and a frequency of 6.0 kHz. The conductivity sensor array concentration limit of detection (SNR = 3) was determined to be 7.1 microM for alanine. The separation efficiency was found to be 6.4 x 10(4), 2.0 x 10(3), 4.8 x 10(3), and 3.4 x 10(2) plates for the mu-CEC of the oligonucleotides and mu-CZE of the amino acids, peptides

  9. [Preparation of elastic porous cell scaffold fabricated with combined polydimethylsiloxane (PDMS) and hydroxyapatite (HA)].

    PubMed

    Yang, Yang; Lan, Ding; Huang, Yan; Li, Yanming; Wang, Yuren; Sun, Lianwen; Fan, Yubo

    2014-06-01

    Polydimethylsiloxane (PDMS) and hydroxyapatite (HA) were combined in our laboratory to fabricate an elastic porous cell scaffold with pore-forming agent, and then the scaffold was used as culture media for rat bone marrow derived mesenchymal stem cells (rBMSCs). Different porous materials (square and circular in shape) were prepared by different pore-forming agents (NaCl or paraffin spheres) with adjustable porosity (62%-76%). The HA crystals grew on the wall of hole when the material was exposed to SBF solutions, showing its biocompatibility and ability to support the cells to attach on the materials. PMID:25219247

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

    PubMed Central

    Gong, Xiuqing; Wen, Weijia

    2009-01-01

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

  11. Tunable wetting behavior of nanostructured poly(dimethylsiloxane) by plasma combination treatments

    NASA Astrophysics Data System (ADS)

    Peter, Nicolas J.; Zhang, Xiao-Sheng; Chu, Shi-Gan; Zhu, Fu-Yun; Seidel, Helmut; Zhang, Hai-Xia

    2012-11-01

    This letter reports on the tunable wetting behavior of poly(dimethylsiloxane) (PDMS) via the combination of nanostructuring and plasma treatment. The PDMS is first micro/nanostructured by an integrated casting process. Subsequently, an inductively coupled plasma is used to modify the siloxanes' surface chemistry. Sulfur hexafluoride, fluoroform, as well as octafluorocyclobutane plasma were applied to treat PDMS samples successively. By optimizing the treatment parameters, tunable wettability of the siloxane was observed, i.e., superhydrophilicity and superhydrophobicity. The stability of its wetting behavior has been demonstrated after 24 h. This stable and tunable wettability extends the applications of PDMS in microfluidic systems.

  12. [Microchip free flow isoelectric focusing with immobilized pH gradient on monolithic materials].

    PubMed

    Han, Bin; Wang, Pingli; Zhang, Lihua; Qu, Feng; Liang, Zhen; Deng, Yulin; Zhang, Yukui

    2009-07-01

    Microchip free flow electrophoresis (microFFE) is a significant microscale technique for the continuous pre-fractionation and the preparation of valuable biological samples. In our recent work, monolithic polyacylamide (PAM) materials were polymerized in microchamber by ultraviolet (UV) initiated polymerization. With the further immobilization of a stable pH gradient on the monolith, a novel microchip free flow isoelectric focusing (microFF-IEF) with monolithic immobilized pH gradient (M-IPG) materials was developed, by which fluorescein-5-isothiocyanate (FITC) labeled glycin, proline and lysine, with a minimum pI difference of 0.33 units, were well separated with a resolution higher than that performed by traditional microFF-IEF. Our experimental results demonstrate that by microFF-IEF with M-IPG, not only the interference of mobile carrier ampholytes in buffer, usually indispensable in traditional microFF-IEF, on the further separation by other techniques and the identification by mass spectrometry (MS) could be avoided, but also the improved resolution and detection sensitivity could be obtained compared with traditional microFF-IEF. Therefore, such a novel technique might be promising in microscale consecutive separation and preparation of samples. PMID:19938489

  13. Design and operation of a portable scanner for high performance microchip capillary array electrophoresis.

    PubMed

    Scherer, James R; Liu, Peng; Mathies, Richard A

    2010-11-01

    We have developed a compact, laser-induced fluorescence detection scanner, the multichannel capillary array electrophoresis portable scanner (McCAEPs) as a platform for electrophoretic detection and control of high-throughput, integrated microfluidic devices for genetic and other analyses. The instrument contains a confocal optical system with a rotary objective for detecting four different fluorescence signals, a pneumatic system consisting of two pressure/vacuum pumps and 28 individual addressable solenoid valves for control of on-chip microvalves and micropumps, four Polymerase Chain Reaction (PCR) temperature control systems, and four high voltage power supplies for electrophoresis. The detection limit of the instrument is ~20 pM for on-chip capillary electrophoresis of fluorescein dyes. To demonstrate the system performance for forensic short tandem repeat (STR) analysis, two experiments were conducted: (i) electrophoretic separation and detection of STR samples on a 96-lane microfabricated capillary array electrophoresis microchip. Fully resolved PowerPlex(®) 16 STR profiles amplified from 1 ng of 9947A female standard DNA were successfully obtained; (ii) nine-plex STR amplification, sample injection, separation, and fluorescence detection of 100-copy 9948 male standard DNA in a single integrated PCR- capillary electrophoresis microchip. These results demonstrate that the McCAEPs can be used as a versatile control and detection instrument that operates integrated microfluidic devices for high-performance forensic human identification. PMID:21133459

  14. Utilizing Microchip Capillary Electrophoresis Electrospray Ionization for Hydrogen Exchange Mass Spectrometry

    PubMed Central

    Black, William A.; Stocks, Bradley B.; Mellors, J. Scott; Engen, John R.; Ramsey, J. Michael

    2015-01-01

    Hydrogen exchange (HX) mass spectrometry (MS) of complex mixtures requires a fast, reproducible, and high peak capacity separation prior to MS detection. The current paradigm relies on liquid chromatography (LC) with fast gradients performed at low temperatures to minimize back exchange. Unfortunately, under these conditions, the efficiency of LC is limited due to resistance to mass transfer, reducing the capability to analyze complex samples. Capillary electrophoresis (CE), on the other hand, is not limited by resistance to mass transfer, enabling very rapid separations that are not adversely affected by low temperature. Previously, we have demonstrated an integrated microfluidic device coupling CE with electrospray ionization (ESI) capable of very rapid and high efficiency separations. In this work, we demonstrate the utility of this microchip CE-ESI device for HX MS. High speed CE-ESI of a bovine hemoglobin pepsin digestion was performed in 1 minute with a peak capacity of 62 versus a similar LC separation performed in 7 minutes with peak capacity of 31. A room temperature CE method performed in 1.25 minutes provided similar deuterium retention as an 8.5 minute LC method conducted at 0 °C. Separation of a complex mixture with CE was done with considerably better speed and nearly triple the peak capacity than the equivalent separation by LC. Overall the results indicate the potential utility of microchip CE-ESI for HX MS. PMID:25992468

  15. Neoplasia and granulomas surrounding microchip transponders in Damaraland mole rats (Cryptomys damarensis).

    PubMed

    Sura, R; French, R A; Goldman, B D; Schwartz, D R

    2011-07-01

    Damaraland mole rats (Cryptomys damarensis) are among the longest-living rodents, with a maximum longevity of approximately 16 years. As one of the few mammals termed eusocial, these animals have been used in behavioral, genetic, metabolic, and physiologic research at the University of Connecticut since 1997. For individual identification at 3 to 4 months of age, mole rats were subcutaneously implanted with microchip transponders (11 mm in length) in the dorsal cervical region. In 2007, 2 of the 90 implanted adults, 10-year-old and 9-year-old females, developed subcutaneous masses at the site of the implant. Histopathological and immunohistochemical examinations revealed amelanotic melanoma and fibrosarcoma, respectively, with metastasis of the amelanotic melanoma. In 2008, a total of 3 adult males were castrated as part of a sex behavior study; 3 months later, all 3 castrated males developed subcutaneous masses around their implants, whereas none of the noncastrated males had masses. After an additional 9 months, these masses were found to be granulomas. To the authors' knowledge, this is the first report of neoplasia in this species. Both the tumors and the granulomas surrounded the microchip transponder. PMID:20724516

  16. Design and operation of a portable scanner for high performance microchip capillary array electrophoresis

    NASA Astrophysics Data System (ADS)

    Scherer, James R.; Liu, Peng; Mathies, Richard A.

    2010-11-01

    We have developed a compact, laser-induced fluorescence detection scanner, the multichannel capillary array electrophoresis portable scanner (McCAEPs) as a platform for electrophoretic detection and control of high-throughput, integrated microfluidic devices for genetic and other analyses. The instrument contains a confocal optical system with a rotary objective for detecting four different fluorescence signals, a pneumatic system consisting of two pressure/vacuum pumps and 28 individual addressable solenoid valves for control of on-chip microvalves and micropumps, four Polymerase Chain Reaction (PCR) temperature control systems, and four high voltage power supplies for electrophoresis. The detection limit of the instrument is ˜20 pM for on-chip capillary electrophoresis of fluorescein dyes. To demonstrate the system performance for forensic short tandem repeat (STR) analysis, two experiments were conducted: (i) electrophoretic separation and detection of STR samples on a 96-lane microfabricated capillary array electrophoresis microchip. Fully resolved PowerPlex® 16 STR profiles amplified from 1 ng of 9947A female standard DNA were successfully obtained; (ii) nine-plex STR amplification, sample injection, separation, and fluorescence detection of 100-copy 9948 male standard DNA in a single integrated PCR- capillary electrophoresis microchip. These results demonstrate that the McCAEPs can be used as a versatile control and detection instrument that operates integrated microfluidic devices for high-performance forensic human identification.

  17. Rapid authentication of ginseng species using microchip electrophoresis with laser-induced fluorescence detection.

    PubMed

    Qin, Jianhua; Leung, Frederick C; Fung, Yingsing; Zhu, Derong; Lin, Bingcheng

    2005-02-01

    Ginseng is one of the most expensive Chinese herbal medicines and the effectiveness of ginseng depends strongly on its botanical sources and the use of different parts of the plants. In this study, a microchip electrophoresis method coupled with the polymerase chain reaction (PCR)-short tandem repeats (STR) technique was developed for rapid authentication of ginseng species. A low viscosity hydroxypropyl methylcellulose (HPMC) solution was used as the sieving matrix for separation of the amplified STR fragments. The allele sizing of the amplified PCR products could be detected within 240 s or less. Good reproducibility and accuracy of the fragment size were obtained with the relative standard deviation for the allele sizes less than 1.0% (n=11). At two microsatellite loci (CT 12, CA 33), American ginseng had a different allele pattern on the electropherograms compared with that of the Oriental ginseng. Moreover, cultivated and wild American ginseng can be distinguished on the basis of allele sizing. This work establishes the feasibility of fast genetic authentication of ginseng species by use of microchip electrophoresis. PMID:15750870

  18. Occupational safety and health implications of the millennium bug: embedded microchips.

    PubMed

    Anderson, V P

    1999-06-01

    Personnel working in the field of environmental safety and health need to be aware that their exposure monitoring equipment as well as various laboratory and work site test and safety systems are candidates for a Y2K problem. The focus here is on the Y2K problem associated with embedded microchips contained in measurement and analytical equipment with internal date functions. With the turn of the century, the year 99 (i.e., 1999) will turn to 00 (i.e., 2000). The expectation is that the date change over will result in some form of malfunction or failure. The media has provided us with basic information on Y2K, particularly as it impacts computer hardware and software users. We know less, however, about how the Y2K issue may affect date-sensitive embedded microchips in safety and health equipment. To manage this problem, we propose a familiar public health strategy involving risk assessment (surveillance and prioritizing) and risk management (intervention/contingency planning). Success in dealing with Y2K-embedded chips will be increased by engaging managers, operators, employee-management safety teams, safety professionals and their organizations, trade associations, local, state and federal regulatory agencies, and the public, where appropriate. A list of Internet sites is provided with information on managing problems arising from date-dependent embedded chips and the Y2K problem. PMID:10429729

  19. Multi-pulse drug delivery from a resorbable polymeric microchip device

    NASA Astrophysics Data System (ADS)

    Grayson, Amy C. Richards; Choi, Insung S.; Tyler, Betty M.; Wang, Paul P.; Brem, Henry; Cima, Michael J.; Langer, Robert

    2003-11-01

    Controlled-release drug delivery systems have many applications, including treatments for hormone deficiencies and chronic pain. A biodegradable device that could provide multi-dose drug delivery would be advantageous for long-term treatment of conditions requiring pulsatile drug release. In this work, biodegradable polymeric microchips were fabricated that released four pulses of radiolabelled dextran, human growth hormone or heparin in vitro. Heparin that was released over 142 days retained on average 96 +/- 12% of its bioactivity. The microchips were 1.2 cm in diameter, 480-560 μm thick and had 36 reservoirs that could each be filled with a different chemical. The devices were fabricated from poly(L-lactic acid) and had poly(D,L-lactic-co-glycolic acid) membranes of different molecular masses covering the reservoirs. A drug delivery system can be designed with the potential to release pulses of different drugs at intervals after implantation in a patient by using different molecular masses or materials for the membrane.

  20. Low-power microwave-mediated heating for microchip-based PCR.

    PubMed

    Marchiarullo, Daniel J; Sklavounos, Angelique H; Oh, Kyudam; Poe, Brian L; Barker, N Scott; Landers, James P

    2013-09-01

    Microwave energy has been used to rapidly heat food and drinks for decades, in addition to assisting other chemical reactions. However, only recently has microwave energy been applied in microfluidic systems to heat solution in reaction chambers, in particular, the polymerase chain reaction (PCR). One of the difficulties in developing microwave-mediated heating on a microchip is the construction of the appropriate architecture for delivery of the energy to specific micro-areas on the microchip. This work employs commercially-available microwave components commonly used in the wireless communications industry to generate a microwave signal, and a microstrip transmission line to deliver the energy to a 1 μL reaction chamber fabricated in plastic microdevices. A model was developed to create transmission lines that would optimally transmit energy to the reaction chamber at a given frequency, minimizing energy usage while focusing microwave delivery to the target chamber. Two different temperature control methods were demonstrated, varying microwave power or frequency. This system was used to amplify a fragment of the lambda-phage genome, thereby demonstrating its potential for integration into a portable PCR system. PMID:23843031

  1. Use of Recordable Compact Discs to Fabricate Electrodes for Microchip-based Analysis Systems

    PubMed Central

    Kirkpatrick, Douglas C.; Antwi, Christiana; Martin, R. Scott

    2010-01-01

    This work demonstrates that recordable compact discs (CDs) that contain gold as a reflective layer can be used as an electrode substrate for microchip-based analysis systems. A fabrication procedure that enables the reproducible patterning of multiple electrodes has been developed. It is shown that the microelectrodes can be integrated within a PDMS-based fluidic network and used for amperometric detection of electroactive analytes at both single and dual microelectrodes. A detailed comparison is made between the CD-based patterned electrodes and electrodes made by the traditional method of sputtering gold and titanium adhesion layers onto a glass substrate. It is also shown that mercury can be electrodeposited onto a CD-based microelectrode and the amalgam electrode used to selectively detect thiols. Finally, it is demonstrated that a decoupler for microchip-based electrophoresis can be made by electrodepositing palladium onto a gold electrode and a separate downstream gold working electrode can be used for amperometric detection. These CD-based patterned electrodes are attractive alternatives for situations where device cost is of a concern or sputtering facilities are unavailable. PMID:21031142

  2. In-channel amperometric detection for microchip electrophoresis using a wireless isolated potentiostat

    PubMed Central

    Gunasekara, Dulan B.; Hulvey, Matthew K.; Lunte, Susan M.

    2012-01-01

    The combination of microchip electrophoresis (ME) with amperometric detection leads to a number of analytical challenges that are associated with isolating the detector from the high voltages used for the separation. While methods such as end-channel alignment and the use of decouplers have been employed, they have limitations. A less common method has been to utilize an electrically isolated potentiostat. This approach allows placement of the working electrode directly in the separation channel without using a decoupler. This paper explores the use of microchip electrophoresis and electrochemical detection (ME-EC) with an electrically isolated potentiostat for the separation and in-channel detection of several biologically important anions. The separation employed negative polarity voltages and tetradecyltrimethylammonium bromide (TTAB, as a buffer modifier) for the separation of nitrite (NO2-), glutathione (GSH), ascorbic acid (AA), and tyrosine (Tyr). A half-wave potential (E½) shift of approximately negative 500 mV was observed for NO2- and H2O2 standards in the in-channel configuration compared to end channel. Higher separation efficiencies were observed for both NO2- and H2O2 with the in-channel detection configuration. The limits of detection were approximately two-fold lower and the sensitivity was approximately two-fold higher for in-channel detection of nitrite when compared to end-channel. The application of this microfluidic device for the separation and detection of biomarkers related to oxidative stress is described. PMID:21437918

  3. Enhanced performance of Cr,Yb:YAG microchip laser by bonding Yb:YAG crystal.

    PubMed

    Cheng, Ying; Dong, Jun; Ren, Yingying

    2012-10-22

    Highly efficient, laser-diode pumped Yb:YAG/Cr,Yb:YAG self-Q-switched microchip lasers by bonding Yb:YAG crystal have been demonstrated for the first time to our best knowledge. The effect of transmission of output coupler (T(oc)) on the enhanced performance of Yb:YAG/Cr,Yb:YAG microchip lasers has been investigated and found that the best laser performance was achieved with T(oc) = 50%. Slope efficiency of over 38% was achieved. Average output power of 0.8 W was obtained at absorbed pump power of 2.5 W; corresponding optical-to-optical efficiency of 32% was obtained. Laser pulses with pulse width of 1.68 ns, pulse energy of 12.4 μJ, and peak power of 7.4 kW were obtained. The lasers oscillated in multi-longitudinal modes. The wide separation of longitudinal modes was attributed to the mode selection by combined etalon effect of Cr,Yb:YAG, Yb:YAG thin plates and output coupler. Stable periodical pulse trains at different pump power levels have been observed owing to the longitudinal modes coupling and competition. PMID:23187245

  4. Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2

    NASA Astrophysics Data System (ADS)

    Loiko, P.; Yoon, S. J.; Serres, J. M.; Mateos, X.; Beecher, S. J.; Birch, R. B.; Savitski, V. G.; Kemp, A. J.; Yumashev, K.; Griebner, U.; Petrov, V.; Aguiló, M.; Díaz, F.; Mackenzie, J. I.

    2016-08-01

    High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77-450 K. At room-temperature, the maximum stimulated emission cross-section is σSE = 21.4 × 10-20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ in KGW is practically temperature independent at 115 ± 5 μs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ∼2.5 × 10-17 cm3/s. When cut along the Ng optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ∼4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 μm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated.

  5. Microchip laser operation of Tm,Ho:KLu(WO₄)₂ crystal.

    PubMed

    Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Yumashev, Konstantin; Kuleshov, Nikolai; Petrov, Valentin; Griebner, Uwe; Aguiló, Magdalena; Díaz, Francesc

    2014-11-17

    A microchip laser is realized on the basis of a monoclinic Tm,Ho-codoped KLu(WO₄)₂crystal cut for light propagation along the Ng optical indicatrix axis. This crystal cut provides positive thermal lens with extremely weak astigmatism, S/M = 4%. High sensitivity factors, M = dD/dP(abs), of 24.9 and 24.1 m(-1)/W for the mg- and pg- tangential planes are calculated with respect to the absorbed pump power. Such thermo-optic behavior is responsible for mode stabilization in the plano-plano microchip laser cavity, as well as the demonstrated perfect circular beam profile (M(2) < 1.1). Maximum continuous-wave output power of 450 mW is obtained with a slope efficiency of 31%. A set of output couplers is employed to achieve lasing in the spectral range of 2060-2096 nm. The increase of output coupler transmission results in deterioration of the laser performance attributed to the increased up-conversion losses. PMID:25402038

  6. A Continuous-Flow Polymerase Chain Reaction Microchip With Regional Velocity Control

    PubMed Central

    Li, Shifeng; Fozdar, David Y.; Ali, Mehnaaz F.; Li, Hao; Shao, Dongbing; Vykoukal, Daynene M.; Vykoukal, Jody; Floriano, Pierre N.; Olsen, Michael; McDevitt, John T.; Gascoyne, Peter R.C.; Chen, Shaochen

    2009-01-01

    This paper presents a continuous-flow polymerase chain reaction (PCR) microchip with a serpentine microchannel of varying width for “regional velocity control.” Varying the channel width by incorporating expanding and contracting conduits made it possible to control DNA sample velocities for the optimization of the exposure times of the sample to each temperature phase while minimizing the transitional periods during temperature transitions. A finite element analysis (FEA) and semi-analytical heat transfer model was used to determine the distances between the three heating assemblies that are responsible for creating the denaturation (96 °C), hybridization (60 °C), and extension (72 °C) temperature zones within the microchip. Predictions from the thermal FEA and semi-analytical model were compared with temperature measurements obtained from an infrared (IR) camera. Flow-field FEAs were also performed to predict the velocity distributions in the regions of the expanding and contracting conduits to study the effects of the microchannel geometry on flow recirculation and bubble nucleation. The flow fields were empirically studied using micro particle image velocimetry (μ-PIV) to validate the flow-field FEA’s and to determine experimental velocities in each of the regions of different width. Successful amplification of a 90 base pair (bp) bacillus anthracis DNA fragment was achieved. PMID:19829760

  7. Analysis of intracellular reducing levels in human hepatocytes on three-dimensional focusing microchip.

    PubMed

    Xu, Chunxiu; Cai, Longfei

    2014-02-01

    A novel three-dimensional hydrodynamic focusing microfluidic device integrated with high-throughput cell sampling and detection of intracellular contents is presented. It has a pivotal role in maintaining the reducing environment in cells. Intracellular reducing species such as vitamin C and glutathione in normal and tumor cells were labeled by a newly synthesized 2,2,6,6-tetramethyl-piperidine-1-oxyl-based fluorescent probe. Hepatocytes are adherent cells, which are prone to attaching to the channel surface. To avoid the attachment of cells on the channel surface, a single channel microchip with three sheath-flow channels located on both sides of and below the sampling channel was developed. Hydrostatic pressure generated by emptying the sample waste reservoir was used as driving force of fluid on the microchip. Owing to the difference between the liquid levels of the reservoirs, the labeled cells were three-dimensional hydrodynamically focused and transported from the sample reservoir to the sample waste reservoir. Hydrostatic pressure takes advantage of its ease of generation on a microfluidic chip without any external pressure pump, which drives three sheath-flow streams to constrain a sample flow stream into a narrow stream to avoid blockage of the sampling channel by adhered cells. The intracellular reducing levels of HepG2 cells and L02 cells were detected by home-built laser-induced fluorescence detector. The analysis throughput achieved in this microfluidic system was about 59-68 cells/min. PMID:23297173

  8. Light emitting diode, photodiode-based fluorescence detection system for DNA analysis with microchip electrophoresis.

    PubMed

    Hall, Gordon H; Glerum, D Moira; Backhouse, Christopher J

    2016-02-01

    Electrophoretic separation of fluorescently end-labeled DNA after a PCR serves as a gold standard in genetic diagnostics. Because of their size and cost, instruments for this type of analysis have had limited market uptake, particularly for point-of-care applications. This might be changed through a higher level of system integration and lower instrument costs that can be realized through the use of LEDs for excitation and photodiodes for detection--if they provide sufficient sensitivity. Here, we demonstrate an optimized microchip electrophoresis instrument using polymeric fluidic chips with fluorescence detection of end-labeled DNA with a LOD of 0.15 nM of Alexa Fluor 532. This represents orders of magnitude improvement over previously reported instruments of this type. We demonstrate the system with an electrophoretic separation of two PCR products and their respective primers. We believe that this is the first LED-induced fluorescence microchip electrophoresis system with photodiode-based detection that could be used for standard applications of PCR and electrophoresis. PMID:26412502

  9. Self-alignment in the stacking of microchips with mist-induced water droplets

    NASA Astrophysics Data System (ADS)

    Chang, Bo; Sariola, Veikko; Jääskeläinen, Mirva; Zhou, Quan

    2011-01-01

    This paper reports a novel and versatile water droplet self-alignment technique where the water is delivered in mist form onto the assembly site. The droplet forming process has been carefully investigated using machine vision, where each individual droplet on the microchip surface can be identified and the volume per surface area can be calibrated at a specific time. The result reveals that the volume of water droplets on the assembly surface grows linearly as a function of time. Self-alignment based on the mist-induced droplets has been studied, where a robotic microgripper is used to deliver the microchips on the assembly site. The paper also investigates the maximum tolerance of the initial placement error in stacking SU-8 chips 200 × 200 × 70 µm in size, and the possibility of stacking two SU-8 chips of different dimensions using the proposed self-alignment technique. Moreover, self-alignment of chips on hydrophilic/hydrophobic patterns covered by mist-induced water droplets has been studied. The experimental results indicate that this novel self-alignment technique is very promising. Furthermore, a statistical model has been used to validate the experimental results.

  10. Passive Q-switching of microchip lasers based on Ho:YAG ceramics.

    PubMed

    Lan, R; Loiko, P; Mateos, X; Wang, Y; Li, J; Pan, Y; Choi, S Y; Kim, M H; Rotermund, F; Yasukevich, A; Yumashev, K; Griebner, U; Petrov, V

    2016-06-20

    A Ho:YAG ceramic microchip laser pumped by a Tm fiber laser at 1910 nm is passively Q-switched by single- and multi-layer graphene, single-walled carbon nanotubes (SWCNTs), and Cr2+:ZnSe saturable absorbers (SAs). Employing SWCNTs, this laser generated an average power of 810 mW at 2090 nm with a slope efficiency of 68% and continuous wave to Q-switching conversion efficiency of 70%. The shortest pulse duration was 85 ns at a repetition rate of 165 kHz, and the pulse energy reached 4.9 μJ. The laser performance and pulse stability were superior compared to graphene SAs even for a different number of graphene layers (n=1 to 4). A model for the description of the Ho:YAG laser Q-switched by carbon nanostructures is presented. This modeling allowed us to estimate the saturation intensity for multi-layered graphene and SWCNT SAs to be 1.2±0.2 and 7±1  MW/cm2, respectively. When using Cr2+:ZnSe, the Ho:YAG microchip laser generated 11 ns/25 μJ pulses at a repetition rate of 14.8 kHz. PMID:27409113

  11. Microchip-based capillary electrophoresis for determination of lactate dehydrogenase isoenzymes.

    PubMed

    Zhuang, Gui-Sheng; Liu, Jing; Jia, Chun-Ping; Jin, Qing-Hui; Zhao, Jian-Long; Wang, Hui-min

    2007-06-01

    This article describes a novel microchip-based capillary electrophoresis and oncolumn enzymatic reaction analysis protocol for lactate dehydrogenase (LDH) isoenzymes with a home-made xenon lamp-induced fluorescence detection system. A microchip integrated with a temperature-control unit is designed and fabricated for low-temperature electrophoretic separation of LDH isoenzymes, optimal enzyme reaction temperature control, and product detection. A four-step operation and temperature control are employed for the determination of LDH activity by on-chip monitoring of the amount of incubation product of NADH during the fixed incubation period and at a fixed temperature. Experiments on the determination of LDH standard sample and serum LDH isoenzymes from a healthy adult donor are carried out. The results are comparable with those obtained by conventional CE. Shorter analysis times and a more stable and lower background baseline can be achieved. The efficient separation of different LDH forms indicates the potential of microfluidic devices for isoenzyme assay. PMID:17623478

  12. Identification of chemical warfare agents using a portable microchip-based detection device

    NASA Astrophysics Data System (ADS)

    Petkovic-Duran, K.; Swallow, A.; Sexton, B. A.; Glenn, F.; Zhu, Y.

    2011-12-01

    Analysis of chemical warfare agents (CWAs) and their degradation products is an important verification component in support of the Chemical Weapons Convention and urgently demanding rapid and reliable analytical methods. A portable microchip electrophoresis (ME) device with contactless conductivity (CCD) detection was developed for the in situ identification of CWA and their degradation products. A 10mM MES/His, 0.4mM CTAB - based separation electrolyte accomplished the analysis of Sarin (GB), Tabun( GA) and Soman (GD) in less than 1 min, which is the fastest screening of nerve agents achieved with portable ME and CCD based detection methods to date. Reproducibility of detection was successfully demonstrated on simultaneous detection of GB (200ppm) and GA (278ppm). Reasonable agreement for the four consecutive runs was achieved with the mean peak time for Sarin of 29.15s, and the standard error of 0.58s or 2%. GD and GA were simultaneously detected with their degradation products methylphosphonic acid (MPA), pinacolyl methylphosphonic acid (PMPA) and O-Ethyl Phosphorocyanidate (GAHP and GAHP1) respectively. The detection limit for Sarin was around 35ppb. To the best of our knowledge this is the best result achieved in microchip electrophoresis and contactless conductivity based detection to date.

  13. Effect of Compressive Stresses on Leakage Currents in Microchip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2012-01-01

    Microchip tantalum capacitors are manufactured using new technologies that allow for production of small size capacitors (down to EIA case size 0402) with volumetric efficiency much greater than for regular chip capacitors. Due to a small size of the parts and leadless design they might be more sensitive to mechanical stresses that develop after soldering onto printed wiring boards (PWB) compared to standard chip capacitors. In this work, the effect of compressive stresses on leakage currents in capacitors has been investigated in the range of stresses up to 200 MPa. Significant, up to three orders of magnitude, variations of currents were observed after the stress exceeds a certain critical level that varied from 10 MPa to 180 MPa for capacitors used in this study. A stress-induced generation of electron traps in tantalum pentoxide dielectric is suggested to explain reversible variations of leakage currents in tantalum capacitors. Thermo-mechanical characteristics of microchip capacitors have been studied to estimate the level of stresses caused by assembly onto PWB and assess the risk of stress-related degradation and failures. Keywords: tantalum capacitors, leakage current, soldering, reliability, mechanical stress.

  14. Coupled-cavity electro-optically {ital Q}-switched Nd:YVO{sub 4} microchip lasers

    SciTech Connect

    Zayhowski, J.J.; Dill, C. III

    1995-04-01

    Nd:YVO{sub 4} microchip lasers have been electro-optically {ital Q} switched to produce 12-{mu}J pulses of 115-ps duration at repetition rates of up to 1 kHz. At a repetition rate of 2.25 MHz, 0.16-{mu}J pulses with an 8.8-ns duration were obtained.

  15. Silver-cemented frit formation for the stabilization of the packing structure in the microchannel of electrochromatographic microchips.

    PubMed

    Park, Jongman; Oh, Hyejin; Jeon, In-Sun

    2011-10-28

    A simple but effective frit formation technique was developed to stabilize the packing structure inside the microchannel of capillary electrochromatographic microchips, utilizing the electroless plating technique. A Ag(NH(3))(2)(+) solution was allowed to diffuse through the colloidal silica packing in the microchannel from the reservoir of the microchip for a limited amount of time, and then it was reduced by an excess amount of formaldehyde solution. A frit structure of ~70 μm in length was formed at the entrance of the microchannel without clogging when treated with 1mM Ag(NH(3))(2)(+) ion and formaldehyde for 30s and 150 s, respectively. The formation of the frit structure was confirmed by a scanning electron microscopy. The stability of the packing structure was tested rigorously and then confirmed by applying alternating electroosmotic flows back and forth with pulsed potential steps on both sides of the frit structure. The effect of the treatment on the electrochromatograms was evaluated after the microchips were repeatedly used and stored for a long period of time. The results indicated that the silver-cemented frit structure extended the lifetime of the fully packed CEC microchips distinctly. PMID:21945197

  16. From Bonding Wires to Banding Women. Proceedings of the International Consultation on Micro-Chips Technology (Manila, Philippines, October 1986).

    ERIC Educational Resources Information Center

    Center for Women's Resources, Quezon City (Philippines).

    In October 1986, 40 women from 12 countries gathered in the Philippines for a 10-day meeting of organizers, educators, and workers affected by and confronting the international electronics industry in microchip plants and in automated offices. Participants were from Malaysia, Indonesia, Thailand, the Philippines, Hong Kong, Japan, the Netherlands,…

  17. Silicones containing pendant biocides for antifouling coatings.

    PubMed

    Thomas, Johnson; Choi, Seok-Bong; Fjeldheim, Renae; Boudjouk, Philip

    2004-01-01

    The preparation of biocide-incorporated silicone coatings for antifouling/fouling release applications is described. The biocide Triclosan (5-chloro-2-(2, 4-dichlorophenoxy) phenol) was modified with alkenyl moieties and incorporated into a silicone backbone through covalent bonds. The presence of the biocide on the coating surface was expected to deter fouling organisms from attaching to the surface of the coating. Allyl glycidyl ether was used to provide crosslink functionalities. Resins were cured using vinyl-terminated polydimethylsiloxane for hydrosilyl functionality and 1, 3-cyclohexane-bis (methylamine) for epoxy crosslinking functionality. Coatings were characterized by static water contact angle measurements and dynamic mechanical thermal analysis. Synthetic control over the incorporation of crosslink functionalities within the polymer resin allowed tuning of the surface of the coating and of mechanical properties. Resistance to macrofouling was tested by static immersion tests in the Indian River Lagoon at the Florida Institute of Technology from 15 October 2003 to 13 November 2003. Preliminary results showed that the coatings prepared from biocide-incorporated silicones with the appropriate bulk modulus significantly reduced macrofouling. PMID:15621644

  18. Fluoropolymer surface coatings to control droplets in microfluidic devices.

    PubMed

    Riche, Carson T; Zhang, Chuchu; Gupta, Malancha; Malmstadt, Noah

    2014-06-01

    We have demonstrated the application of low surface energy fluoropolymer coatings onto poly(dimethylsiloxane) (PDMS) microfluidic devices for droplet formation and extraction-induced merger of droplets. Initiated chemical vapor deposition (iCVD) was used to pattern fluoropolymer coatings within microchannels based on geometrical constraints. In a two-phase flow system, the range of accessible flow rates for droplet formation was greatly enhanced in the coated devices. The ability to controllably apply the coating only at the inlet facilitated a method for merging droplets. An organic spacer droplet was extracted from between a pair of aqueous droplets. The size of the organic droplet and the flow rate controlled the time to merge the aqueous droplets; the process of merging was independent of the droplet sizes. Extraction-induced droplet merging is a robust method for manipulating droplets that could be applied in translating multi-step reactions to microfluidic platforms. PMID:24722827

  19. Fiber optic ultrasound transducers with carbon/PDMS composite coatings

    NASA Astrophysics Data System (ADS)

    Mosse, Charles A.; Colchester, Richard J.; Bhachu, Davinder S.; Zhang, Edward Z.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2014-03-01

    Novel ultrasound transducers were created with a composite of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) that was dip coated onto the end faces of optical fibers. The CNTs were functionalized with oleylamine to allow for their dissolution in xylene, a solvent of PDMS. Ultrasound pulses were generated by illuminating the composite coating with pulsed laser light. At distances of 2 to 16 mm from the end faces, ultrasound pressures ranged from 0.81 to 0.07 MPa and from 0.27 to 0.03 MPa with 105 and 200 μm core fibers, respectively. Using an optical fiber hydrophone positioned adjacent to the coated 200 µm core optical fiber, ultrasound reflectance measurements were obtained from the outer surface of a sheep heart ventricle. The results of this study suggest that ultrasound transducers that comprise optical fibers with CNT-PDMS composite coatings may be suitable for miniature medical imaging probes.

  20. Comparison of dielectric properties of polydimethylsiloxane (PDMS) grafted polyacrylates/nano alumina and nano silica composites

    NASA Astrophysics Data System (ADS)

    Murudkar, Vrishali V.; Gaonkar, Amita A.; Deshpande, V. D.; Mhaske, S. T.

    2016-05-01

    Polydimethylsiloxane possess very poor mechanical properties. However, typically the initial modulus and durability of material is low and to improve this aspect a reinforcement phase is required. For the composite to be effective the filler must be with large aspect ratio i.e. with large surface area to volume ratio. Nano alumina (Al2O3) and nano silica (SiO2) are materials of choice for nanocomposite design. Grafted Polydimethylsiloxane (G-PDMS) and nano alumina and nano Silica composites have been prepared, by solvent casting method. FTIR study reveals that there is bonding overlap in G-PDMS/SiO2 nano composites. In dielectric study, it is observed that G-PDMS/SiO2 nano composites were more conducting in nature than G-PDMS/ Al2O3 nano composites. G-PDMS/ Al2O3 nano composites showed enhanced dielectric constant and less loss of energy than G-PDMS/SiO2 nano composites.

  1. Silicon-on-glass based microchip for protein sensing and analysis by using confocal microscopy and MALDI-TOF

    NASA Astrophysics Data System (ADS)

    Kim, M. S.; Cho, S. H.; Kim, B. G.; Kim, Y. K.

    2006-01-01

    We propose a prototype of silicon-on-glass microchip for protein detection by bead-based affinity chromatography. The microchip has five channels integrated by composing one beads reactor per one channel. Especially, an effective protein analysis mechanism is presented where the three protein-pretreatment processes are simultaneously performed on a single beads reactor: selective detection (purification / sensing), pre-concentration and protein digestion. Since the five channels are closely spaced in parallel on the microchip, it is possible to inspect the five different detection results on real-time in a single microscope image. The microchip is fabricated on silicon-on-glass (SiOG) to make a mechanically strong and vertically transparent structure for efficient fluid interconnection and fluorescence detection, respectively. Within the microchip, the grid-type filter is formed on channel output to physically trap 38 ~ 50 μm diameter microbeads. The dimension of one grid is 30 × 30 μm2. The volume flow rate was investigated experimentally on the case of bead-packed chamber, and the resulted value was compared to that of the case of hollow chamber. In this research, we used self-cleavage free aptazymes as detection ligands immobilized on polystyrene microbeads. The target proteins are firstly on-chip concentrated and fluorescence-detected (confocal microscopy), and secondly checked off-chip by using MALDI-TOF. If the two analyses are used cooperatively, it is expected that the accuracy in diagnostic analysis will be enhanced in biosensing system. Especially by using this free aptazymes system, we don't need to consider the requirement of fluorescence tagging and the difficulty of eluting antibody-bound proteins from microbeads without bad effects of harsh elution conditions in protease treatment. We analyzed the on-bead detection of HCV replicase and HCV helicase respectively by measuring fluorescence intensities at different concentrations, and also performed a

  2. Selective Permeating Properties of Butanol and Water through Polystyrene- b-polydimethylsiloxane- b-polystyrene Pervaporation Membranes

    NASA Astrophysics Data System (ADS)

    Shin, Chaeyoung; Baer, Zachary; Chen, X. Chelsea; Ozcam, A. Evren; Clark, Douglas; Balsara, Nitash

    2015-03-01

    Polystyrene- b-polydimethylsiloxane- b-polystyrene (SDS) membranes have been studied in butanol-water binary pervaporation experiments and pervaporation experiments integrated with viable fermentation broths. Polydimethylsiloxane has been widely known to be a suitable material for separating organic chemicals from aqueous solutions, and it thus provides a continuous matrix phase in SDS membranes for permeation of small molecules. The polystyrene block provides mechanical stability to maintain the membrane structure in the pervaporation membranes. We take advantage of these features to fabricate a thin and butanol-selective SDS membrane for in situ product removal in fermentation.

  3. Aluminide coatings

    DOEpatents

    Henager, Jr; Charles, H [Kennewick, WA; Shin, Yongsoon [Richland, WA; Samuels, William D [Richland, WA

    2009-08-18

    Disclosed herein are aluminide coatings. In one embodiment coatings are used as a barrier coating to protect a metal substrate, such as a steel or a superalloy, from various chemical environments, including oxidizing, reducing and/or sulfidizing conditions. In addition, the disclosed coatings can be used, for example, to prevent the substantial diffusion of various elements, such as chromium, at elevated service temperatures. Related methods for preparing protective coatings on metal substrates are also described.

  4. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  5. Application of microchip assay system for the measurement of C-reactive protein in human saliva.

    PubMed

    Christodoulides, Nicolaos; Mohanty, Sanghamitra; Miller, Craig S; Langub, M Chris; Floriano, Pierre N; Dharshan, Priya; Ali, Mehnaaz F; Bernard, Bruce; Romanovicz, Dwight; Anslyn, Eric; Fox, Philip C; McDevitt, John T

    2005-03-01

    In the last decade, saliva has been advocated as a non-invasive alternative to blood as a diagnostic fluid. However, use of saliva has been hindered by the inadequate sensitivity of current methods to detect the lower salivary concentrations of many constituents compared to serum. Furthermore, developments in the areas related to lab-on-a-chip systems for saliva-based point of care diagnostics are complicated by the high viscosity and heterogeneous properties associated with this diagnostic fluid. The biomarker C-reactive protein (CRP) is an acute phase reactant and a well-accepted indicator of inflammation. Numerous clinical studies have established elevated serum CRP as a strong, independent risk factor for the development of cardiovascular disease (CVD). CVD has also been associated with oral infections (i.e. periodontal diseases) and there is evidence that systemic CRP may be a link between the two. Clinical measurements of CRP in serum are currently performed with "high sensitivity" CRP (hsCRP) enzyme-linked immunosorbent assay (ELISA) tests that lack the sensitivity for the detection of this important biomarker in saliva. Because measurement of salivary CRP may represent a novel approach for diagnosing and monitoring chronic inflammatory disease, including CVD and periodontal diseases, the objective of this study was to apply an ultra-sensitive microchip assay system for the measurement of CRP in human saliva. Here, we describe this novel lab-on-a-chip system in its first application for the measurement of CRP in saliva and demonstrate its advantages over the traditional ELISA method. The increased sensitivity of the microchip system (10 pg ml(-1) of CRP with 1000-fold dilution of saliva sample) is attributed to its inherent increased signal to noise ratio, resulting from the higher bead surface area available for antigen/antibody interactions and the high stringency washes associated with this approach. Finally, the microchip assay system was utilized in

  6. Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

    PubMed Central

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Azrin Shah, Nabila Farhana; Shasmin, Hanie Nadia; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E′: 0.225) and glass transition temperature (Tg: −58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials. PMID:26927116

  7. Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors.

    PubMed

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Shah, Nabila Farhana Azrin; Shasmin, Hanie Nadia; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E': 0.225) and glass transition temperature (Tg: -58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials. PMID:26927116

  8. Facile Synthesis of Conductive Polypyrrole Wrinkle Topographies on Polydimethylsiloxane via a Swelling-Deswelling Process and Their Potential Uses in Tissue Engineering.

    PubMed

    Aufan, M Rifqi; Sumi, Yang; Kim, Semin; Lee, Jae Young

    2015-10-28

    Electrically conducting biomaterials have gained great attention in various biomedical studies especially to influence cell and tissue responses. In addition, wrinkling can present a unique topography that can modulate cell-material interactions. In this study, we developed a simple method to create wrinkle topographies of conductive polypyrrole (wPPy) on soft polydimethylsiloxane surfaces via a swelling-deswelling process during and after PPy polymerization and by varying the thickness of the PPy top layers. As a result, various features of wPPy in the range of the nano- and microscales were successfully obtained. In vitro cell culture studies with NIH 3T3 fibroblasts and PC12 neuronal cells indicated that the conductive wrinkle topographies promote cell adhesion and neurite outgrowth of PC12 cells. Our studies help to elucidate the design of the surface coating and patterning of conducting polymers, which will enable us to simultaneously provide topographical and electrical signals to improve cell-surface interactions for potential tissue-engineering applications. PMID:26444932

  9. Massive parallel analysis of the binding specificity of histone-like protein HU to single- and double-stranded DNA with generic oligodeoxyribonucleotide microchips.

    SciTech Connect

    Krylov, A. S.; Zasedateleva, O. A.; Prokopenko, D. V.; Rouviere-Yaniv, J.; Mirzabekov, A. D.; Biochip Technology Center; Engelhardt Inst. of Molecular Biology; Inst. de Biologie Physico-Chimique

    2001-06-15

    A generic hexadeoxyribonucleotide microchip has been applied to test the DNA-binding properties of HU histone-like bacterial protein, which is known to have a low sequence specificity. All 4096 hexamers flanked within 8mers by degenerate bases at both the 3'- and 5'-ends were immobilized within the 100 x 100 x 20 mm polyacrylamide gel pads of the microchip. Single-stranded immobilized oligonucleotides were converted in some experiments to the double-stranded form by hybridization with a specified mixture of 8mers. The DNA interaction with HU was characterized by three type of measurements: (i) binding of FITC-labeled HU to microchip oligonucleotides; (ii) melting curves of complexes of labeled HU with single-stranded microchip oligonucleotides; (iii) the effect of HU binding on melting curves of microchip double-stranded DNA labeled with another fluorescent dye, Texas Red. Large numbers of measurements of these parameters were carried out in parallel for all or many generic microchip elements in real time with a multi-wavelength fluorescence microscope. Statistical analysis of these data suggests some preference for HU binding to G/C-rich single-stranded oligonucleotides. HU complexes with double-stranded microchip 8mers can be divided into two groups in which HU binding either increased the melting temperature (T{sub m}) of duplexes or decreased it. The stabilized duplexes showed some preference for presence of the sequence motifs AAG, AGA and AAGA. In the second type of complex, enriched with A/T base pairs, the destabilization effect was higher for longer stretches of A/T duplexes. Binding of HU to labeled duplexes in the second type of complex caused some decrease in fluorescence. This decrease also correlates with the higher A/T content and lower T{sub m}. The results demonstrate that generic microchips could be an efficient approach in analysis of sequence specificity of proteins.

  10. Hydrogel plug for independent sample and buffer handling in continuous microchip capillary electrophoresis

    NASA Astrophysics Data System (ADS)

    Puchberger-Enengl, Dietmar; Bipoun, Mireille; Smolka, Martin; Krutzler, Christian; Keplinger, Franz; Vellekoop, Michael J.

    2013-05-01

    In microchip capillary electrophoresis most frequently electrokinetic sample injection is utilized, which does not allow pressure driven sample handling and is sensitive for pressure drops due to different reservoir levels. For efficient field tests a multitude of samples have to be processed with the least amount of external equipment. We present the use of a hydrogel plug to separate the sample from clean buffer to enable independent sample change and buffer refreshment. In-situ polymerization of the gel does away with complex membrane fabrication techniques. The sample is electrokinetically injected through the gel and subsequently separated by a voltage between the second gel inlet and the buffer outlet. By blocking of disturbing flows by the gel barrier a well-defined ion plug is obtained. After each experiment, the sample and the separation channel can be flushed independently, allowing for a continuous operation mode in order to process multiple samples.

  11. Low-temperature microchip nonaqueous capillary electrophoresis of aliphatic primary amines: applications to Titan chemistry.

    PubMed

    Cable, Morgan L; Stockton, Amanda M; Mora, Maria F; Willis, Peter A

    2013-01-15

    We demonstrate microchip nonaqueous capillary electrophoresis (μNACE) analysis of primary aliphatic amines (C1-C18) in ethanol down to -20 °C as a first step in adapting microfluidic protocols for in situ analysis on Titan. To our knowledge, this is the first report of a nonaqueous separation at -20 °C on-chip. Limits of detection (LODs) ranged from 1.0 nM to 2.6 nM, and we identified several primary amines ranging in length from C2 to C16 in Titan aerosol analogue (tholin) samples; new amines were also detected in a tholin sample exposed to oxygen and liquid water. This preliminary work validates the sensitivity and efficacy of microfluidic chemical analysis of complex organics with relevance to Titan aerosols and surface deposits. PMID:23214444

  12. [Detection of short tandem repeat (STR) polymorphisms by microchip electrophoresis for individual identification of cattle].

    PubMed

    Yamaguchi, Akihiro; Shimizu, Kaori; Mishima, Takashi; Hattori, Hideki; Katsuda, Shin-ichi; Sato, Hidetaka; Ueda, Nobuo; Sato, Noriyuki

    2006-12-01

    A simple and rapid detection of short tandem repeat (STR) markers was studied as a screening test for individual identification of cattle. DNAs were extracted from eight commercial beef samples by a proteinase K-boil method followed by purification with 2-propanol precipitation. Five STR markers, known to be highly polymorphic, were amplified by PCR and analyzed both by a conventional sequencing analysis (SEQ) and by a proposed microchip electrophoresis (MEP). Every marker revealed high polymorphism, such as 5-9 alleles in SEQ analysis, and 4-6 alleles in MEP analysis. This simple and rapid MEP analysis is expected to be an effective screening tool with use of confirmatory SEQ analysis. PMID:17228791

  13. Radially polarized and pulsed output from passively Q-switched Nd:YAG ceramic microchip laser.

    PubMed

    Li, Jian-lang; Ueda, Ken-ichi; Musha, Mitsuru; Zhong, Lan-xiang; Shirakawa, Akira

    2008-11-15

    For the first time, to the best of our knowledge, a radially polarized laser pulse was produced from a passively Q-switched Nd:YAG ceramic microchip laser with a piece of Cr4+:YAG crystal as the saturable absorber and multilayer concentric subwavelength grating as the polarization-selective output coupler. The averaged laser power reached 450 mW with a slope efficiency of 30.2%. The laser pulse had a maximum peak power of 759 W, a minimum pulse duration of 86 ns, and a 6.7 kHz repetition rate at 3.7 W absorbed pump power. The polarization degree of the radially polarized pulse was measured to be as high as 97.4%. Such a radially polarized laser pulse with a high peak power and a short width is important to numerous applications such as metal cutting. PMID:19015709

  14. Recent Developments in Instrumentation for Capillary Electrophoresis and Microchip-Capillary Electrophoresis

    PubMed Central

    Felhofer, Jessica L.; Blanes, Lucas; Garcia, Carlos D.

    2010-01-01

    Over the last years there has been an explosion in the number of developments and applications of capillary electrophoresis (CE) and microchip-CE. In part, this growth has been the direct consequence of recent developments in instrumentation associated with CE. This review, which is focused on contributions published in the last five years, is intended to complement the papers presented in this special issue dedicated to Instrumentation and to provide an overview on the general trend and some of the most remarkable developments published in the areas of high voltage power supplies, detectors, auxiliary components, and compact systems. It also includes few examples of alternative uses of and modifications to traditional CE instruments. PMID:20665910

  15. A high repetition rate passively Q-switched microchip laser for controllable transverse laser modes

    NASA Astrophysics Data System (ADS)

    Dong, Jun; Bai, Sheng-Chuang; Liu, Sheng-Hui; Ueda, Ken-Ichi; Kaminskii, Alexander A.

    2016-05-01

    A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for versatile controllable transverse laser modes has been demonstrated by adjusting the position of the Nd:YVO4 crystal along the tilted pump beam direction. The pump beam diameter-dependent asymmetric saturated inversion population inside the Nd:YVO4 crystal governs the oscillation of various Laguerre-Gaussian, Ince-Gaussian and Hermite-Gaussian modes. Controllable transverse laser modes with repetition rates over 25 kHz and up to 183 kHz, depending on the position of the Nd:YVO4 crystal, have been achieved. The controllable transverse laser beams with a nanosecond pulse width and peak power over hundreds of watts have been obtained for potential applications in optical trapping and quantum computation.

  16. Over 0.5 MW green laser from sub-nanosecond giant pulsed microchip laser

    NASA Astrophysics Data System (ADS)

    Zheng, Lihe; Taira, Takunori

    2016-03-01

    A sub-nanosecond green laser with laser head sized 35 × 35 × 35 mm3 was developed from a giant pulsed microchip laser for laser processing on organic superconducting transistor with a flexible substrate. A composite monolithic Y3Al5O12 (YAG) /Nd:YAG/Cr4+:YAG/YAG crystal was designed for generating giant pulsed 1064 nm laser. A fibercoupled 30 W laser diode centered at 808 nm was used with pump pulse duration of 245 μs. The 532 nm green laser was obtained from a LiB3O5 (LBO) crystal with output energy of 150 μJ and pulse duration of 268 ps. The sub-nanosecond green laser is interesting for 2-D ablation patterns.

  17. An Integrated Three-Dimensional Solution for Wire-Sweep Analysis in Microchip Encapsulation

    NASA Astrophysics Data System (ADS)

    Yang, Wen-Hsien; Hsu, David C.; Chang, Rong-Yeu

    2004-06-01

    This paper presents an integrated true three-dimensional simulation of resin flow and wire sweep in microchip encapsulation. A FVM-based decoupled solution algorithm with the hybrid elements capability is adopted to calculate the resin flow during mold filling. Furthermore, a highly flexible mesh generation technique especially tailored for the IC packages is also proposed to mesh the model with high quality element both in the flow and gapwize directions. Thanks to the efficiency of the proposed methodology in terms of CPU time and memory requirement, the industrial packages with complex geometry and high pin count can be analyzed with minimum model simplification. Finally, a user-friendly integrated environment is also developed to link the flow analysis with structure analysis to provide the total solution for wire sweep assessment.

  18. A Photochromic Sensor Microchip for High-performance Multiplex Metal Ions Detection

    NASA Astrophysics Data System (ADS)

    Huang, Yu; Li, Fengyu; Ye, Changqing; Qin, Meng; Ran, Wei; Song, Yanlin

    2015-04-01

    Current multi-analytes chips are limited with requiring numbers of sensors, complex synthesis and compounds screen. It is expected to develop new principles and techniques to achieve high-performance multi-analytes testing with facile sensors. Here, we investigated the correlative multi-states properties of a photochromic sensor (spirooxazine), which is capable of a selective and cross-reactive sensor array for discriminated multi-analytes (11 metal ions) detection by just one sensing compound. The multi-testing sensor array performed in dark, ultraviolet or visual stimulation, corresponding to different molecular states of spirooxazine metal ions coordination. The facile photochromic microchip contributes a multi-states array sensing method, and will open new opportunities for the development of advanced discriminant analysis for complex analytes.

  19. A photochromic sensor microchip for high-performance multiplex metal ions detection.

    PubMed

    Huang, Yu; Li, Fengyu; Ye, Changqing; Qin, Meng; Ran, Wei; Song, Yanlin

    2015-01-01

    Current multi-analytes chips are limited with requiring numbers of sensors, complex synthesis and compounds screen. It is expected to develop new principles and techniques to achieve high-performance multi-analytes testing with facile sensors. Here, we investigated the correlative multi-states properties of a photochromic sensor (spirooxazine), which is capable of a selective and cross-reactive sensor array for discriminated multi-analytes (11 metal ions) detection by just one sensing compound. The multi-testing sensor array performed in dark, ultraviolet or visual stimulation, corresponding to different molecular states of spirooxazine metal ions coordination. The facile photochromic microchip contributes a multi-states array sensing method, and will open new opportunities for the development of advanced discriminant analysis for complex analytes. PMID:25853794

  20. Difference in microchip electrophoretic mobility between partially and fully PEGylated poly(amidoamine) dendrimers.

    PubMed

    Park, Eun Ji; Na, Dong Hee

    2015-11-01

    The objective of this study was to investigate the difference in electrophoretic mobility between partially and fully poly(ethylene glycol)-conjugated poly(amidoamine) dendrimers (part-PEG-PAMAM and full-PEG-PAMAM, respectively) using a microchip capillary gel electrophoresis (MCGE). While MCGE allowed size-based separation of PEG-PAMAMs prepared with monomethoxy PEG-nitrophenyl carbonate, full-PEG-PAMAMs migrated slower than part-PEG-PAMAMs that were similar in size or larger. When the measured molecular weights obtained from MCGE analysis and the calculated molecular weights were plotted, each part-PEG-PAMAM and full-PEG-PAMAM showed correlation coefficients greater than 0.98. This study indicates that MCGE would be useful for characterizing PEG-PAMAMs with different PEGylation degrees. PMID:26253023

  1. Multi-track single- and dual-channel plastic microchips for electrospray mass spectrometry.

    PubMed

    Leuthold, Luc Alexis; Reymond, Frédéric; Rossier, Joël S; Varesio, Emmanuel; Hopfgartner, Gérard

    2010-01-01

    Disposable plastic electrospray chips are particularly attractive for the automated analysis of organic compounds and organometallic compounds. Automated multi-track chip-based infusion electrospray mass spectrometry of low molecular weight compounds using an eight-channel plastic chip is presented. For that purpose, the commercial interface of a triple quadrupole linear ion trap was modified. A dual-channel plastic microchip, where two physically separated channels arrive very close to each other at the chip tip, was used to perform lock-mass accurate mass measurements on a quadrupole-time-of-flight instrument. The same chip was used to demonstrate the formation of an organometallic complex in solution on the chip tip. Furthermore, the potential to control the flow rate of each channel individually, which opens new possibilities in the study of supramolecular complexes, is discussed. PMID:20065514

  2. Response of microchip solid-state laser to external frequency-shifted feedback and its applications

    PubMed Central

    Tan, Yidong; Zhang, Shulian; Zhang, Song; Zhang, Yongqing; Liu, Ning

    2013-01-01

    The response of the microchip solid-state Nd:YAG laser, which is subjected to external frequency-shifted feedback, is experimentally and theoretically analysed. The continuous weak response of the laser to the phase and amplitude of the feedback light is achieved by controlling the feedback power level, and this system can be used to achieve contact-free measurement of displacement, vibration, liquid evaporation and thermal expansion with nanometre accuracy in common room conditions without precise environmental control. Furthermore, a strong response, including chaotic harmonic and parametric oscillation, is observed, and the spectrum of this response, as examined by a frequency-stabilised Nd:YAG laser, indicates laser spectral linewidth broadening. PMID:24105389

  3. Rapid separation of phosphopeptides by microchip electrophoresis-electrospray ionization mass spectrometry.

    PubMed

    Ollikainen, Elisa; Bonabi, Ashkan; Nordman, Nina; Jokinen, Ville; Kotiaho, Tapio; Kostiainen, Risto; Sikanen, Tiina

    2016-04-01

    Protein phosphorylation is a significant biological process, but separation of phosphorylated peptide isomers is often challenging for many analytical techniques. We developed a microchip electrophoresis (MCE) method for rapid separation of phosphopeptides with on-chip electrospray ionization (ESI) facilitating online sample introduction to the mass spectrometer (MS). With the method, two monophosphorylated positional isomers of insulin receptor peptide (IR1A and IR1B) and a triply phosphorylated insulin receptor peptide (IR3), all with the same amino acid sequence, were separated from the nonphosphorylated peptide (IR0) in less than one minute. For efficient separation of the positional peptide isomers from each other derivatization with 9-fluorenylmethyl reagents (either chloroformate, Fmoc-Cl, or N-succinimidyl carbonate, Fmoc-OSu) was required before the analysis. The derivatization improved not only the separation of the monophosphorylated positional peptide isomers in MCE, but also identification of the phosphorylation site based on MS/MS. PMID:26931427

  4. A Photochromic Sensor Microchip for High-performance Multiplex Metal Ions Detection

    PubMed Central

    Huang, Yu; Li, Fengyu; Ye, Changqing; Qin, Meng; Ran, Wei; Song, Yanlin

    2015-01-01

    Current multi-analytes chips are limited with requiring numbers of sensors, complex synthesis and compounds screen. It is expected to develop new principles and techniques to achieve high-performance multi-analytes testing with facile sensors. Here, we investigated the correlative multi-states properties of a photochromic sensor (spirooxazine), which is capable of a selective and cross-reactive sensor array for discriminated multi-analytes (11 metal ions) detection by just one sensing compound. The multi-testing sensor array performed in dark, ultraviolet or visual stimulation, corresponding to different molecular states of spirooxazine metal ions coordination. The facile photochromic microchip contributes a multi-states array sensing method, and will open new opportunities for the development of advanced discriminant analysis for complex analytes. PMID:25853794

  5. Polyurethane/poly(vinyl alcohol) hydrogel coating improves the cytocompatibility of neural electrodes

    PubMed Central

    Li, Mei; Zhou, Hai-han; Li, Tao; Li, Cheng-yan; Xia, Zhong-yuan; Duan, Yanwen Y.

    2015-01-01

    Neural electrodes, the core component of neural prostheses, are usually encapsulated in polydimethylsiloxane (PDMS). However, PDMS can generate a tissue response after implantation. Based on the physicochemical properties and excellent biocompatibility of polyurethane (PU) and poly(vinyl alcohol) (PVA) when used as coating materials, we synthesized PU/PVA hydrogel coatings and coated the surface of PDMS using plasma treatment, and the cytocompatibility to rat pheochromocytoma (PC12) cells was assessed. Protein adsorption tests indicated that the amount of protein adsorption onto the PDMS substrate was reduced by 92% after coating with the hydrogel. Moreover, the PC12 cells on the PU/PVA-coated PDMS showed higher cell density and longer and more numerous neurites than those on the uncoated PDMS. These results indicate that the PU/PVA hydrogel is cytocompatible and a promising coating material for neural electrodes to improve their biocompatibility. PMID:26889197

  6. Combinatorial materials research applied to the development of new surface coatings XVI: fouling-release properties of amphiphilic polysiloxane coatings.

    PubMed

    Stafslien, Shane J; Christianson, David; Daniels, Justin; VanderWal, Lyndsi; Chernykh, Andrey; Chisholm, Bret J

    2015-01-01

    High-throughput methods were used to prepare and characterize the fouling-release (FR) properties of an array of amphiphilic polysiloxane-based coatings possessing systematic variations in composition. The coatings were derived from a silanol-terminated polydimethylsiloxane, a silanol-terminated polytrifluorpropylmethylsiloxane (CF3-PDMS), 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane (TMS-PEG), methyltriacetoxysilane and hexamethyldisilazane-treated fumed silica. The variables investigated were the concentration of TMS-PEG and the concentration of CF3-PDMS. In general, it was found that the TMS-PEG and the CF3-PDMS had a synergist effect on FR properties with these properties being enhanced by combining both compounds into the coating formulations. In addition, reattached adult barnacles removed from coatings possessing both TMS-PEG and relatively high levels of CF3-PDMS displayed atypical base-plate morphologies. The majority of the barnacles removed from these coatings exhibited a cupped or domed base-plate as compared to the flat base-plate observed for the control coating that did not contain TMS-PEG or CF3-PDMS. Coating surface analysis using water contact angle measurements indicated that the presence of CF3-PDMS facilitated migration of TMS-PEG to the coating/air interface during the film formation/curing process. In general, coatings containing both TMS-PEG and relatively high levels of CF3-PDMS possessed excellent FR properties. PMID:25647177

  7. Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2

    NASA Astrophysics Data System (ADS)

    Loiko, P.; Yoon, S. J.; Serres, J. M.; Mateos, X.; Beecher, S. J.; Birch, R. B.; Savitski, V. G.; Kemp, A. J.; Yumashev, K.; Griebner, U.; Petrov, V.; Aguiló, M.; Díaz, F.; Mackenzie, J. I.

    2016-08-01

    High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77-450 K. At room-temperature, the maximum stimulated emission cross-section is σSE = 21.4 × 10-20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ in KGW is practically temperature independent at 115 ± 5 μs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ∼2.5 × 10-17 cm3/s. When cut along the Ng optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ∼4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 μm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated.

  8. Microchip amplifier for in vitro, in vivo, and automated whole cell patch-clamp recording.

    PubMed

    Harrison, Reid R; Kolb, Ilya; Kodandaramaiah, Suhasa B; Chubykin, Alexander A; Yang, Aimei; Bear, Mark F; Boyden, Edward S; Forest, Craig R

    2015-02-15

    Patch clamping is a gold-standard electrophysiology technique that has the temporal resolution and signal-to-noise ratio capable of reporting single ion channel currents, as well as electrical activity of excitable single cells. Despite its usefulness and decades of development, the amplifiers required for patch clamping are expensive and bulky. This has limited the scalability and throughput of patch clamping for single-ion channel and single-cell analyses. In this work, we have developed a custom patch-clamp amplifier microchip that can be fabricated using standard commercial silicon processes capable of performing both voltage- and current-clamp measurements. A key innovation is the use of nonlinear feedback elements in the voltage-clamp amplifier circuit to convert measured currents into logarithmically encoded voltages, thereby eliminating the need for large high-valued resistors, a factor that has limited previous attempts at integration. Benchtop characterization of the chip shows low levels of current noise [1.1 pA root mean square (rms) over 5 kHz] during voltage-clamp measurements and low levels of voltage noise (8.2 μV rms over 10 kHz) during current-clamp measurements. We demonstrate the ability of the chip to perform both current- and voltage-clamp measurement in vitro in HEK293FT cells and cultured neurons. We also demonstrate its ability to perform in vivo recordings as part of a robotic patch-clamping system. The performance of the patch-clamp amplifier microchip compares favorably with much larger commercial instrumentation, enabling benchtop commoditization, miniaturization, and scalable patch-clamp instrumentation. PMID:25429119

  9. Microchip electrophoretic separation and fluorescence detection of chelerythrine and sanguinarine in medicinal plants.

    PubMed

    Sun, Yue; Li, Yuanyuan; Zeng, Jiajian; Lu, Qixian; Li, Paul C H

    2015-09-01

    A new method has been developed for separation of chelerythrine and sanguinarine in medicinal plants used in traditional Chinese medicine (TCM). The separation is achieved by microchip electrophoresis (CE) using laser-induced fluorescence detection. The CE separation is achieved by using a hydro-organic medium as the electrolyte buffer. The experimental results are consistent with the prediction by theory in terms of resolution and migration speed because of the low Joule heat generated in microchip CE. In addition, formamide was found to have a potential for separation of molecules with similar chemical structures. Based on these findings, a run buffer containing 50% formamide was used to separate chelerythrine (CHE) and sanguinarine (SAN). The influencing factors, such as solvent of run buffer, pH of buffer, separation distance, and separation voltage, were optimized. Baseline separation of chelerythrine and sanguinarine was achieved within 120 s under an electrical voltage of 1.8 kV. Good linearity was observed in the concentration range of 0.15-550 μg mL(-1) (r=0.9993) for CHE and in the range of 0.3-600 μg mL(-1) (r=0.9998) for SAN. A low limit of detection (LOD) was achieved because of the high sensitivity achieved by laser-induced fluorescence detection (i.e. 5.0 ng mL(-1) and 2.0 ng mL(-1) for CHE and SAN, respectively). The contents of CHE are found to be 641.8±7.5 and 134.0±2.3 mg/kg in extracts of Macleaya cordata and Chelidonium majus, respectively, with good recovery of above 99%. The corresponding values for SAN found in these Chinese herbal extracts are 681.8±7.9 mg/kg and 890.5±8.9 mg/kg, respectively. PMID:26003696

  10. Simple filter microchip for rapid separation of plasma and viruses from whole blood

    PubMed Central

    Wang, ShuQi; Sarenac, Dusan; Chen, Michael H; Huang, Shih-Han; Giguel, Francoise F; Kuritzkes, Daniel R; Demirci, Utkan

    2012-01-01

    Sample preparation is a significant challenge for detection and sensing technologies, since the presence of blood cells can interfere with the accuracy and reliability of virus detection at the nanoscale for point-of-care testing. To the best of our knowledge, there is not an existing on-chip virus isolation technology that does not use complex fluidic pumps. Here, we presented a lab-on-a-chip filter device to isolate plasma and viruses from unprocessed whole blood based on size exclusion without using a micropump. We demonstrated that viruses (eg, HIV) can be separated on a filter-based chip (2-μm pore size) from HIV-spiked whole blood at high recovery efficiencies of 89.9% ± 5.0%, 80.5% ± 4.3%, and 78.2% ± 3.8%, for viral loads of 1000, 10,000 and 100,000 copies/mL, respectively. Meanwhile, 81.7% ± 6.7% of red blood cells and 89.5% ± 2.4% of white blood cells were retained on 2 μm pore–sized filter microchips. We also tested these filter microchips with seven HIV-infected patient samples and observed recovery efficiencies ranging from 73.1% ± 8.3% to 82.5% ± 4.1%. These results are first steps towards developing disposable point-of-care diagnostics and monitoring devices for resource-constrained settings, as well as hospital and primary care settings. PMID:23055720

  11. A microchip integrating cell array positioning with in situ single-cell impedance measurement.

    PubMed

    Guo, Xiaoliang; Zhu, Rong; Zong, Xianli

    2015-10-01

    This paper presents a novel microarray chip integrating cell positioning with in situ, real-time and long-time impedance measurement on a single cell. The microchip integrates a plurality of quadrupole-electrode units (termed positioning electrodes) patterned into an array with pairs of planar electrodes (termed measuring electrodes) located at the centers of each quadrupole-electrode unit. The positioning electrodes are utilized to trap and position living cells onto the measuring electrodes based on negative dielectrophoresis (nDEP), while the measuring electrodes are used to measure impedances of the trapped single cells. Each measuring electrode has a small footprint area of 7 × 7 μm(2) to ensure inhabiting only one single cell on it. However, the electrode with a small surface area has a low double-layer capacitance when it is immersed in a liquid solution, thus generating a large double-layer impedance, which reduces the sensitivity for impedance measurement on the single cell. To enlarge the effective surface areas of the measuring electrodes, a novel surface-modification process is proposed to controllably construct gold nanostructures on the surfaces of the measuring electrodes while the positioning electrodes are unstained. The double layer capacitances of the modified electrodes are increased by about one order after surface-modification. The developed microchip is used to monitor the adhering behavior of a single HeLa cell by measuring its impedance spectra in real time. The measured impedance is analyzed and used to extract cellular electrical parameters, which demonstrated that the cell compresses the electrical double layer in the process of adherence and adheres onto the measuring electrodes after 4-5 hours. PMID:26282920

  12. In vitro evaluation of a passive radio frequency identification microchip implanted in human molars subjected to compression forces, for forensic purposes of human identification

    PubMed Central

    Moreno, Freddy; Vallejo, Diego; Garzón, Herney; Moreno, Sandra

    2013-01-01

    Objective: To evaluate the in vitro behavior of a passive Radio Frequency Identification (RFID) microchip implanted in human molars subjected to compression forces to determine its technical and clinical viability. Materials and Methods: In vitro experimental study to evaluate the physical behavior of a passive RFID microchip (VeriChip™) implanted in human molars through resin restoration (Filtek P90™ Silorane 3M-ESPE®) to determine the clinical and technical possibilities of the implant and the viability to withstand compression forces exerted by the stomatognathic system during mastication. Results: Through the ANOVA test, it was found that the teeth on which a microchip was implanted show great resistance to compressive forces. It was also evident that teeth with microchips implanted in Class V cavities are more resistant than those implanted in Class I cavities. Conclusions: Although microchip dimensions are big, requiring a sufficiently large cavity, from the biomechanical point of view it is plausible to implant a microchip in a Class V cavity employing restoration material based on resin for forensic purposes of human identification. PMID:24255554

  13. A disposable laser print-cut-laminate polyester microchip for multiplexed PCR via infra-red-mediated thermal control.

    PubMed

    Ouyang, Yiwen; Duarte, Gabriela R M; Poe, Brian L; Riehl, Paul S; dos Santos, Fernando M; Martin-Didonet, Claudia C G; Carrilho, Emanuel; Landers, James P

    2015-12-11

    Infrared (IR)-mediated thermal cycling system, a method proven to be a effective for sub-μL scale polymerase chain reaction (PCR) on microchips, has been integrated with DNA extraction and separation on a glass microchip in a fully integrated micro Total Analysis System by Easley et al., in 2006. IR-PCR has been demonstrated on both glass and PMMA microdevices where the fabrication (bonding) is not trivial. Polyester-toner (PeT) microfluidic devices have significant potential as cost-effective, disposable microdevices as a result of the ease of fabrication (∼$0.25 USD and <10 min per device) and availability of commercial substrates. For the first time, we demonstrate here the thermal cycling in PeT microchips on the IR-PCR system. Undesirable IR absorption by the black-toner bonding layer was eliminated with a spatial filter in the form of an aluminum foil mask. The solution heating rate for a black PeT microchip using a tungsten lamp was 10.1 ± 0.7 °C s(-1) with a cooling rate of roughly -12 ± 0.9 °C s(-1) assisted by forced air cooling. Dynamic surface passivation strategies allowed the successful amplification of a 520 bp fragment of the λ-phage genome (in 11 min) and a 1500 bp region of Azospirillum brasilense. Using a centrosymmetric chamber configuration in a multichamber PeT microchip, homogenous temperature distribution over all chambers was achieved with inter-chamber temperature differences at annealing, extension and denaturing steps of less than ±2 °C. The effectiveness of the multichamber system was demonstrated with the simultaneous amplification of a 390 bp amplicon of human β-globin gene in five PeT PCR microchambers. The relative PCR amplification efficiency with a human β-globin DNA fragment ranged from 70% to 90%, in comparison to conventional thermal cyclers, with an inter-chamber standard deviation of ∼10%. Development of PeT microchips for IR-PCR has the potential to provide rapid, low-volume amplification while

  14. POLYDIMETHYLSILOXANE- COATED IRON AND IRON-OXIDES FOR MAGNETIC SEPARATION OF ORGANICS FROM WATER. (R827015C010)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  15. Surface modification on polydimethylsiloxane-based microchannels with fragmented poly(l-lactic acid) nanosheets.

    PubMed

    Yang, Lu; Okamura, Yosuke; Kimura, Hiroshi

    2015-11-01

    Surface modification is a critical issue in various applications of polydimethylsiloxane (PDMS)-based microfluidic devices. Here, we describe a novel method through which PDMS-based microchannels were successfully modified with fragmented poly(l-lactic acid) (PLLA) nanosheets through a simple patchwork technique that exploited the high level of adhesiveness of PLLA nanosheets. Compared with other surface modification methods, our method required neither complicated chemical modifications nor the use of organic solvents that tend to cause PDMS swelling. The experimental results indicated that the modified PDMS exhibited excellent capacity for preventing the adhesion and activation of platelets. This simple yet efficient method can be used to fabricate the special PDMS microfluidic devices for biological, medical, and even hematological purposes. PMID:26634016

  16. Patterning of gold-polydimethylsiloxane (Au-PDMS) nanocomposites by supersonic cluster beam implantation

    NASA Astrophysics Data System (ADS)

    Ghisleri, C.; Borghi, F.; Ravagnan, L.; Podestà, A.; Melis, C.; Colombo, L.; Milani, P.

    2014-01-01

    Patterned gold-polydimethylsiloxane (Au-PDMS) nanocomposites were fabricated by supersonic cluster beam implantation (SCBI) of neutral gold nanoparticles in PDMS through stencil masks. The influence of nanoparticle dose on the surface roughness and morphology of the micropatterned regions of the nanocomposite was characterized. Nanoparticle implantation causes the swelling of PDMS without affecting substantially the lateral resolution of the patterns. In order to have an insight on the mechanism and the influence of nanoparticle implantation on the polymeric matrix, large-scale molecular dynamics simulations of the implantation process have been performed. The simulations show that even a single cluster impact on PDMS substrate strongly affects the polymer local temperature and density. Our results show that SCBI is a promising methodology for the efficient fabrication of nanocomposite microstructures on polymers with interesting morphological, structural and functional properties.

  17. Hydrophobic nanopatterning on a flexible gas barrier film by using a poly(dimethylsiloxane) elastomer

    NASA Astrophysics Data System (ADS)

    Choi, Jin-Hwan; Kim, Young-Min; Park, Young-Wook; Park, Tae-Hyun; Dong, Ki-Young; Ju, Byeong-Kwon

    2009-04-01

    In this work, we fabricated a hydrophobic and transparent gas barrier film via a nanopatterned poly(dimethylsiloxane) elastomer imprinting on an ultraviolet-curable polymer resin. A Ca degradation method (water permeation rate) and surface energy measurements were used to determine the level of modification of the surface characteristics. As a result, the decreased surface energy from 25.8 to 7.29 mN m-1 led to a lower water vapor transmission rate from 3.06 × 10-1 to 6.24 × 10-2 g m-2 day-1 according to the degree of decreased Ca height from 100 nm. A tunable wettability is beneficial for application where controlling the direction of moisture flow is important, such as in flexible organic electronics.

  18. Self-patterning of a polydimethylsiloxane microlens array on functionalized substrates and characterization by digital holography

    NASA Astrophysics Data System (ADS)

    Merola, F.; Paturzo, M.; Coppola, S.; Vespini, V.; Ferraro, P.

    2009-12-01

    Microlens arrays are realized through a self-arrangement process of thin liquid polymeric polydimethylsiloxane (PDMS) film on a functionalized polar dielectric crystal substrate. The self-arrangement process is named the pyro-electro-wetting mechanism. The substrate, a LiNbO3 (LN) z-cut wafer, has been micro-engineered with periodically poled ferroelectric domains, with the aim to provide an appropriate wettability patterning induced by a thermal stimulus. Different experimental procedures have been explored demonstrating that arrays of thousands of microlenses, having a diameter size of 100 µm and focal lengths ranging between 300 and 1100 µm, can be fabricated. Furthermore, a microscope interference method based on digital holography is adopted for microlens characterization.

  19. Poly(N-vinylpyrrolidone)-modified poly(dimethylsiloxane) elastomers as anti-biofouling materials.

    PubMed

    Wu, Zhaoqiang; Tong, Weifang; Jiang, Wenwen; Liu, Xiaoli; Wang, Yanwei; Chen, Hong

    2012-08-01

    A new method for the modification of poly(dimethylsiloxane) (PDMS) elastomer surfaces with hydrophilic poly(N-vinylpyrrolidone) (PVP) has been developed. PVP chains were grafted from the PDMS surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The resulting surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM) and water contact angle measurements. It was shown that the modified surfaces were strongly hydrophilic, indicating that the PVP grafts dominate the surface and define its properties. The anti-fouling properties of the grafted surfaces were demonstrated in protein adsorption and cell adhesion experiments. Both protein adsorption and cell adhesion were inhibited significantly on the PVP-modified PDMS surfaces compared to unmodified controls. It is concluded that modification by SI-ATRP grafting of PVP is an effective method for the preparation of anti-biofouling PDMS materials. PMID:22510455

  20. Cross-Linking the Surface of Cured Polydimethylsiloxane via Hyperthemal Hydrogen Projectile Bombardment.

    PubMed

    Bao, Chao; Xu, Ke-Qin; Tang, Chang-Yu; Lau, Woon-ming; Yin, Cong-Bin; Zhu, Yan; Mei, Jun; Lee, Jonathan; Hui, David; Nie, Heng-Yong; Liu, Yu

    2015-04-29

    Cross-linking of polydimethylsiloxane (PDMS) is increasingly important with recent focus on its top surface stiffness. In this paper, we demonstrate that hyperthermal hydrogen projectile bombardment, a surface sensitive cross-linking technology, is superior in enhancing the mechanical properties of a cured PDMS surface without significantly degrading its hydrophobicity. Both water contact angle measurements and time-of-flight secondary ion mass spectrometry are used to investigate the variations in surface chemistry and structure upon cross-linking. Using nanoindentation and atomic force microscopy, we confirm that the thickness of the cross-linked PDMS is controllable by the bombardment time, which opens opportunities for tuning cross-linking degree in compliance with arising requirements from the practice. PMID:25849306

  1. Soft lithography of ceramic microparts using wettability-tunable poly(dimethylsiloxane) (PDMS) molds

    NASA Astrophysics Data System (ADS)

    Su, Bo; Zhang, Aijun; Meng, Junhu; Zhang, Zhaozhu

    2016-07-01

    Green alumina microparts were fabricated from a high solid content aqueous suspension by microtransfer molding using air plasma-treated poly(dimethylsiloxane) (PDMS) molds. The wettability of the air plasma-treated PDMS molds spontaneously changed between the hydrophilic and hydrophobic states during the process. Initial hydrophilicity of the air plasma-treated PDMS molds significantly improved the flowability of the concentrated suspension. Subsequent hydrophobic recovery of the air plasma-treated PDMS molds enabled a perfect demolding of the green microparts. Consequently, defect-free microchannel parts of 60 μm and a micromixer with an area of several square centimeters were successfully fabricated. In soft lithography, tuning the wetting behavior of PDMS molds has a great effect on the quality of ceramic microparts. Using wettability-tunable PDMS molds has great potential in producing complex-shaped and large-area ceramic microparts and micropatterns.

  2. Stretchable photo sensor using perylene/graphene composite on ridged polydimethylsiloxane substrate.

    PubMed

    Ali, Shawkat; Bae, Jinho; Lee, Chong Hyun

    2015-11-30

    To apply in wearable electronics, we propose a stretchable photo sensor that detects an inversely changed resistance by varying light intensity, which is stably operated up to 25% axial strain. Especially, the stretchabity of the proposed photo sensor is achived by using a uniform ridged substrate made of polydimethylsiloxane (PDMS). The proposed device is composed of a thin film of perylene/graphene composite, which is sandwiched between bottom and top indium tin oxide (ITO) transparent electrodes fabricated through electro-hydrodynamic (EHD) technique. The electrical conductivity of perylene is improved by blending graphene with it. The resistance of the proposed photo sensor changes from 108 MΩ to 87 MΩ within the light intensity range of 0 to 400 lux, respectively. Furthermore, the flexibility is verified through a bendability test from 16 mm down to 0 mm and a bending endurance test for more than 1000 cycles. Uniform and smooth deposition of the active layer is tested through surface morphology characterization. PMID:26698691

  3. In situ nitrogen-doped graphene grown from polydimethylsiloxane by plasma enhanced chemical vapor deposition.

    PubMed

    Wang, Chundong; Zhou, Yungang; He, Lifang; Ng, Tsz-Wai; Hong, Guo; Wu, Qi-Hui; Gao, Fei; Lee, Chun-Sing; Zhang, Wenjun

    2013-01-21

    Due to its unique electronic properties and wide spectrum of promising applications, graphene has attracted much attention from scientists in various fields. Control and engineering of graphene's semiconducting properties is considered to be key to its applications in electronic devices. Here, we report a novel method to prepare in situ nitrogen-doped graphene by microwave plasma assisted chemical vapor deposition (CVD) using PDMS (polydimethylsiloxane) as a solid carbon source. Based on this approach, the concentration of nitrogen-doping can be easily controlled via the flow rate of nitrogen during the CVD process. X-ray photoelectron spectroscopy results indicated that the nitrogen atoms doped into the graphene lattice were mainly in the forms of pyridinic and pyrrolic structures. Moreover, first-principles calculations show that the incorporated nitrogen atoms can lead to p-type doping of graphene. This in situ approach provides a promising strategy to prepare graphene with controlled electronic properties. PMID:23203220

  4. In situ nitrogen-doped graphene grown from polydimethylsiloxane by plasma enhanced chemical vapor deposition

    SciTech Connect

    Wang, Chundong; Zhou, Yungang; He, Lifang; Ng, Tsz-Wai; Hong, Guo; Wu, Qi-Hui; Gao, Fei; Lee, Chun-Sing; Zhang, Wenjun

    2013-01-21

    Due to its unique electronic properties and wide spectrum of promising applications, graphene has attracted much attention from scientists in various fields. Control and engineering of graphene’s semiconducting properties is considered to be the key of its applications in electronic devices. Here, we report a novel method to prepare in situ nitrogen-doped graphene by microwave plasma assisted chemical vapor deposition (CVD) using PDMS (Polydimethylsiloxane) as a solid carbon source. Based on this approach, the concentration of nitrogen-doping can be easily controlled via the flow rate of nitrogen during the CVD process. X-ray photoelectron spectroscopy results indicated that the nitrogen atoms doped into graphene lattice were mainly in the forms of pyridinic and pyrrolic structures. Moreover, first-principles calculations show that the incorporated nitrogen atoms can lead to p-type doping of graphene. This in situ approach provides a promising strategy to prepare graphene with controlled electronic properties.

  5. Blends of thermoplastic polyurethane and polydimethylsiloxane rubber: assessment of biocompatibility and suture holding strength of membranes.

    PubMed

    Rajan, Krishna Prasad; Al-Ghamdi, Ahmed; Parameswar, Ramesh; Nando, G B

    2013-01-01

    In the present investigation, a compatibilized blend of thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) is prepared by using copolymer of ethylene and methyl acrylate (EMA) as a reactive compatibilizer. Detailed in vitro biocompatibility studies were carried out for this compatibilized blend and the material was found noncytotoxic towards L929 mouse fibroblast subcutaneous connective tissue cell line. Microporosity was created on the surface of membranes prepared from the blend material by adopting the crazing mechanism. Cell proliferation and growth studies on the membranes surface showed that the microporous surface favoured ingrowth of the cells compared with a nonmicroporous surface. Suture holding strength studies indicate that the microporous membranes have enough strength to withstand the cutting and tearing forces through the suture hole. This blend material could be evaluated further to find its suitability in various implant applications. PMID:24454376

  6. Blends of Thermoplastic Polyurethane and Polydimethylsiloxane Rubber: Assessment of Biocompatibility and Suture Holding Strength of Membranes

    PubMed Central

    Al-Ghamdi, Ahmed; Parameswar, Ramesh; Nando, G. B.

    2013-01-01

    In the present investigation, a compatibilized blend of thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) is prepared by using copolymer of ethylene and methyl acrylate (EMA) as a reactive compatibilizer. Detailed in vitro biocompatibility studies were carried out for this compatibilized blend and the material was found noncytotoxic towards L929 mouse fibroblast subcutaneous connective tissue cell line. Microporosity was created on the surface of membranes prepared from the blend material by adopting the crazing mechanism. Cell proliferation and growth studies on the membranes surface showed that the microporous surface favoured ingrowth of the cells compared with a nonmicroporous surface. Suture holding strength studies indicate that the microporous membranes have enough strength to withstand the cutting and tearing forces through the suture hole. This blend material could be evaluated further to find its suitability in various implant applications. PMID:24454376

  7. Effect of cross-link density on carbon dioxide separation in polydimethylsiloxane-norbornene membranes

    DOE PAGESBeta

    Hong, Tao; Niu, Zhenbin; Hu, Xunxiang; Gmernicki, Kevin; Cheng, Shiwang; Fan, Fei; Johnson, J. Casey; Hong, Eunice; Mahurin, Shannon; Jiang, De -en; et al

    2015-01-01

    The development of high performance materials for CO2 separation and capture will significantly contribute to a solution for climate change. In this work, (bicycloheptenyl) ethyl terminated polydimethylsiloxane (PDMSPNB) membranes with varied cross-link densities were synthesized via ring-opening metathesis polymerization. The developed polymer membranes show higher permeability and better selectivity than those of conventional cross-linked PDMS membrane. The achieved performance (CO2 permeability ~ 6800 Barrer and CO2/N2 selectivity ~ 14) is very promising for practical applications. The key to achieving this high performance is the use of an in-situ cross-linking method of the difunctional PDMS macromonomers, which provides lightly cross-linked membranes.more » By combining positron annihilation lifetime spectroscopy, broadband dielectric spectroscopy and gas solubility measurements, we have elucidated the key parameters necessary for achieving their excellent performance.« less

  8. Multiwalled carbon nanotube/polydimethylsiloxane composite films as high performance flexible electric heating elements

    SciTech Connect

    Yan, Jing; Jeong, Young Gyu

    2014-08-04

    High performance elastomeric electric heating elements were prepared by incorporating various contents of pristine multiwalled carbon nanotube (MWCNT) in polydimethylsiloxane (PDMS) matrix by using an efficient solution-casting and curing technique. The pristine MWCNTs were identified to be uniformly dispersed in the PDMS matrix and the electrical percolation of MWCNTs was evaluated to be at ∼0.27 wt. %, where the electrical resistivity of the MWCNT/PDMS composite films dropped remarkably. Accordingly, the composite films with higher MWCNT contents above 0.3 wt. % exhibit excellent electric heating performance in terms of temperature response rapidity and electric energy efficiency at constant applied voltages. In addition, the composite films, which were thermally stable up to 250 °C, showed excellent heating-cooling cyclic performance, which was associated with operational stability in actual electric heating applications.

  9. Shape and feature size control of colloidal crystal-based patterns using stretched polydimethylsiloxane replica molds.

    PubMed

    Choi, Hong Kyoon; Im, Sang Hyuk; Park, O Ok

    2009-10-20

    In this work, we fabricated various patterns using colloidal crystals as master molds via the soft lithography method. Even though colloidal crystals consist of spherical colloidal particles, nonspherical shaped patterns such as rectangular or elongated hexagonal shaped patterns can be fabricated using a stretched polydimethylsiloxane (PDMS) replica mold. The pattern shape and feature size can be easily controlled by changing the stretching axis and ratio of the PDMS replica mold. The deformations of the PDMS mold were simulated using the finite element method, and they are consistent with experimental results. The elongated patterns were used as templates to offer new types of colloidal crystal superlattice structures. A proposed pattern-control method will significantly expand the usefulness and diversity of micro/nanopatterning technology. PMID:19821618

  10. Poly-dimethylsiloxane derivates side chains effect on syntan functionalized Polyamide fabric

    NASA Astrophysics Data System (ADS)

    Migani, V.; Weiss, H.; Massafra, M. R.; Merlo, A.; Colleoni, C.; Rosace, G.

    2011-02-01

    Poly-dimethylsiloxane (PDMS) polymers finishing of Polyamide-6,6 (PA66) fabrics involves ionic interactions between reactive groups on the PDMS polymers and the ones of the textile fabric. Such interactions could be strengthened by a pretreatment with a fixing agent to promote either ion-ion and H-bonding and ion-dipole forces. These forces could contribute towards the building of substantial PDMS-PA66 systems and the achieving of better adhesion properties to fabrics. Four different silicone polymers based on PDMS were applied on a synthetic tanning agent (syntan) finished Polyamide-6,6 fabric under acid conditions. Soxhlet extraction method and ATR FT-IR technique were used to investigate the application conditions. The finishing parameters such as pH and temperature together with fastness, mechanical and performance properties of the treated samples were studied and related to PDMS side chains effect on syntan functionalized Polyamide fabric.

  11. Effect of cross-link density on carbon dioxide separation in polydimethylsiloxane-norbornene membranes

    SciTech Connect

    Hong, Tao; Niu, Zhenbin; Hu, Xunxiang; Gmernicki, Kevin; Cheng, Shiwang; Fan, Fei; Johnson, J. Casey; Hong, Eunice; Mahurin, Shannon; Jiang, De -en; Long, Brian; Mays, Jimmy; Sokolov, Alexei; Saito, Tomonori

    2015-01-01

    The development of high performance materials for CO2 separation and capture will significantly contribute to a solution for climate change. In this work, (bicycloheptenyl) ethyl terminated polydimethylsiloxane (PDMSPNB) membranes with varied cross-link densities were synthesized via ring-opening metathesis polymerization. The developed polymer membranes show higher permeability and better selectivity than those of conventional cross-linked PDMS membrane. The achieved performance (CO2 permeability ~ 6800 Barrer and CO2/N2 selectivity ~ 14) is very promising for practical applications. The key to achieving this high performance is the use of an in-situ cross-linking method of the difunctional PDMS macromonomers, which provides lightly cross-linked membranes. By combining positron annihilation lifetime spectroscopy, broadband dielectric spectroscopy and gas solubility measurements, we have elucidated the key parameters necessary for achieving their excellent performance.

  12. Surface morphology and magnetic property of wrinkled FeGa thin films fabricated on elastic polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Zhang, Shuanglan; Zhan, Qingfeng; Yu, Ying; Liu, Luping; Li, Huihui; Yang, Huali; Xie, Yali; Wang, Baomin; Xie, Shuhong; Li, Run-Wei

    2016-03-01

    We investigated the surface morphology and the magnetic property of wrinkled Fe81Ga19 (FeGa) thin films fabricated in two different processes onto elastic polydimethylsiloxane (PDMS) substrates. The films obtained by directly depositing Ta and FeGa layers on a pre-strained PDMS substrate display a sinusoidally wrinkled surface and a weak magnetic anisotropy. The wavelength and amplitude of the sinusoidal morphology linearly increase with the metallic layer thickness, while the magnetic anisotropy decreases with increasing FeGa thickness. The other films grown by depositing FeGa layer on a wrinkled Ta/PDMS surface show a remarkable uniaxial magnetic anisotropy. The strength of magnetic anisotropy increases with increasing FeGa thickness. The magnetic anisotropy can be ascribed to the surface anisotropy, the magnetostrictive anisotropy, and the shape anisotropy caused, respectively, by the magnetic charges on wavy morphology, the residual mechanical stress, and the inhomogeneous thickness of FeGa films.

  13. Microfabrication of polydimethylsiloxane phantoms to simulate tumor hypoxia and vascular anomaly

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Ren, Wenqi; Yu, Zelin; Dong, Erbao; Zhang, Shiwu; Xu, Ronald X.

    2015-12-01

    We introduce a microfluidic approach to simulate tumor hypoxia and vascular anomaly. Polydimethylsiloxane (PDMS) phantoms with embedded microchannel networks were fabricated by a soft lithography process. A dialysis membrane was sandwiched between two PDMS slabs to simulate the controlled mass transport and oxygen metabolism. A tortuous microchannel network was fabricated to simulate tumor microvasculature. A dual-modal multispectral and laser speckle imaging system was used for oxygen and blood flow imaging in the tumor-simulating phantom. The imaging results were compared with those of the normal vasculature. Our experiments demonstrated the technical feasibility of simulating tumor hypoxia and vascular anomalies using the proposed PDMS phantom. Such a phantom fabrication technique may be potentially used to calibrate optical imaging devices, to study the mechanisms for tumor hypoxia and angiogenesis, and to optimize the drug delivery strategies.

  14. Optical limiting of high-repetition-rate laser pulses by carbon nanofibers suspended in polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Videnichev, Dmitry A.; Belousova, Inna M.

    2014-06-01

    The optical limiting (OL) behavior of carbon nanofibers (CNFs) in polydimethylsiloxane (PDMS) was studied and compared with that of CNFs in water, and polyhedral multi-shell fullerene-like nanostructures (PMFNs) also in water. It was shown that when switching from single-shot to pulse-periodic regime of laser pulses (10 Hz), the CNF in PDMS suspension retains its OL characteristics, while in the aqueous suspensions, considerable degradation of OL characteristics is observed. It was also observed that a powerful laser pulse causes the CNF in PDMS suspension to become opaque for at least three seconds, while such a pulse brings out a bleaching effect in aqueous PMFN and CNF suspensions. The processes of OL degradation in aqueous suspensions, bleaching and darkening of the studied materials are discussed herein.

  15. Parallel combinatorial chemical synthesis using single-layer poly(dimethylsiloxane) microfluidic devices

    PubMed Central

    Dexter, Joseph P.; Parker, William

    2009-01-01

    Improving methods for high-throughput combinatorial chemistry has emerged as a major area of research because of the importance of rapidly synthesizing large numbers of chemical compounds for drug discovery and other applications. In this investigation, a novel microfluidic chip for performing parallel combinatorial chemical synthesis was developed. Unlike past microfluidic systems designed for parallel combinatorial chemistry, the chip is a single-layer device made of poly(dimethylsiloxane) that is extremely easy and inexpensive to fabricate. Using the chip, a 2×2 combinatorial series of amide-formation reactions was performed. The results of this combinatorial synthesis indicate that the new device is an effective platform for running parallel organic syntheses at significantly higher throughput than with past methodologies. Additionally, a design algorithm for scaling up the 2×2 combinatorial synthesis chip to address more complex cases was developed. PMID:20216962

  16. Double Emulsion Generation Using a Polydimethylsiloxane (PDMS) Co-axial Flow Focus Device.

    PubMed

    Cole, Russell H; Tran, Tuan M; Abate, Adam R

    2015-01-01

    Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper presents a polydimethylsiloxane (PDMS) microfluidic device capable of generating water/oil/water double emulsions using a coaxial flow focusing geometry that can be fabricated entirely using soft lithography. Similar to emulsion devices using glass capillaries, double emulsions can be formed in channels with uniform wettability and with dimensions much smaller than the channel sizes. Three dimensional flow focusing geometry is achieved by casting a pair of PDMS slabs using two layer soft lithography, then mating the slabs together in a clamshell configuration. Complementary locking features molded into the PDMS slabs enable the accurate registration of features on each of the slab surfaces. Device testing demonstrates formation of double emulsions from 14 µm to 50 µm in diameter while using large channels that are robust against fouling and clogging. PMID:26780079

  17. Acoustic and relaxation behaviors of polydimethylsiloxane studied by using brillouin and dielectric spectroscopies

    NASA Astrophysics Data System (ADS)

    Lee, Byoung Wan; Ko, Jae-Hyeon; Park, Jaehoon; Shin, Dong-Myeong; Hwang, Yoon-Hwae

    2016-04-01

    The temperature dependences of the acoustic properties and the dielectric relaxation times of polydimethylsiloxane were investigated by using high-resolution Brillouin and broadband dielectric spectroscopies. The longitudinal sound velocity showed a large increase upon approaching the glass transition temperature while the acoustic absorption coefficient exhibited a maximum at ~263 K. Comparison of these results with previous ultrasonic data revealed a substantial frequency dispersion of the acoustic properties of this silicone-based elastomer. The relaxation times derived from the acoustic absorption peaks were consistent with the temperature dependence of the dielectric relaxation time of the structural a process, indicating a strong coupling between the acoustic waves and the segmental motions of the main chains.

  18. Microchip electrospray: cone-jet stability analysis for water-acetonitrile and water-methanol mobile phases.

    PubMed

    Jung, Stephanie; Effelsberg, Uwe; Tallarek, Ulrich

    2011-03-25

    Changes in mobile phase composition during high performance liquid chromatography (HPLC) gradient elution coupled to mass spectrometry (MS) sensitively affect electrospray operation modes. In this work, we identify the influences of dynamic changes in bulk conductivity on the cone-jet stability island for aqueous acetonitrile and aqueous methanol mobile phases commonly used in reversed-phase HPLC. Bulk conductivities of the mobile phases were varied by adding different amounts of formic acid. A commercial microchip-HPLC/ESI-MS configuration was modified to enable in situ electrospray diagnostics by frequency analysis of the microchip emitter current and spray imaging. This approach facilitated the detection of different spray modes together with their onset potentials. The established spray modes are described and the differences in onset potentials and stability regions explained by the physicochemical properties of the electrosprayed liquid. PMID:21333298

  19. A novel capillary electrophoresis microchip with amperometric detection using a Prussian blue-modified indium tin oxide electrode

    NASA Astrophysics Data System (ADS)

    Kim, Ju-Ho; Kang, C. J.; Kim, Yong-Sang

    2005-03-01

    A novel approach to construct a disposable capillary electrophoresis microchip is proposed. The electrocatalytic oxidation of dopamine at a Prussian blue (PB)-modified indium tin oxide (ITO) electrode was described and the amperometric detection of dopamine was then investigated. The PB film on ITO electrode was electrodeposited using FeCl3 and K3Fe(CN)6 mixed solution. Our results indicated that PB film was uniform, smooth, and defect-free. The CE-chip has been tested successfully by detecting dopamine and catechol within a very short time of around 80 sec using an electric field of 60 V/cm. The results also showed that dopamine and catechol mixtures were separated efficiently and rapidly. The microsystems gave a very good reproducibility for peak height and separation time. This microchip is cost effective and adequate for a disposable sensor.

  20. Highly efficient passively Q-switched Yb:YAG microchip lasers under high intensity laser-diode pumping

    NASA Astrophysics Data System (ADS)

    Dong, J.; Wang, G. Y.; Cheng, Y.

    2013-03-01

    A highly efficient Cr4+:YAG passively Q-switched Yb:YAG microchip laser has been demonstrated at room temperature by high-brightness single-emitter laser-diode pumping. The maximum average output power of 1.53 W was obtained at the absorbed pump power of 3.5 W. The optical-to-optical efficiency was 44% with respect to the absorbed pump power. Laser pulses with a pulse width of 2.9 ns, pulse energy of 11.3 μJ, and peak power of 3.9 kW were obtained. The high pump power intensity from a high-brightness single-emitter laser-diode plays an important role in the alleviation of thermal effects and the efficient performance of Cr4+:YAG passively Q-switched Yb:YAG microchip lasers.

  1. Is capillary electrophoresis on microchip devices able to genotype uridine diphosphate glucuronosyltransferase 1A1 TATA-box polymorphisms?

    PubMed

    Minucci, Angelo; Canu, Giulia; De Bonis, Maria; Delibato, Elisabetta; Capoluongo, Ettore

    2014-06-01

    In this commentary, we focused our attention on capillary electrophoresis. It achieves the efficient separation of molecular species by the application of high voltages to samples in solution. Actually, capillary electrophoresis can be performed on microchip devices, based on an automated and miniaturized electrophoresis system, based on lab-on-a-chip technology. By this technology it is possible to separate nucleic acid fragments (DNA or RNA) with respect to sizing accuracy and sizing resolution. Currently, two automated capillary electrophoresis on microchips devices are available: the Agilent 2100 Bioanalyzer and the Experion™ Automated Electrophoresis System. In this study, we evaluated if the CE is able to distinguish the three uridine diphosphate glucuronosyltransferase 1A1 TATA-box genotypes. PMID:24687976

  2. One-step preparation of amino-PEG modified poly(methyl methacrylate) microchips for electrophoretic separation of biomolecules.

    PubMed

    Kitagawa, Fumihiko; Kubota, Kei; Sueyoshi, Kenji; Otsuka, Koji

    2010-12-15

    A simple method for a chemical surface modification of poly(methyl methacrylate) (PMMA) microchips with amino-poly(ethyleneglycol) (PEG-NH(2)) by nucleophilic addition-elimination reaction was developed to improve the separation efficiency and analytical reproducibility in a microchip electrophoresis (MCE) analysis of biomolecules such as proteins and enantiomers. In our procedure, the PEG chains were robustly immobilized only by introducing an aqueous solution of PEG-NH(2) into the PMMA microchannel. The electroosmotic mobilities on the modified chips remained almost constant during 35 days with 37 runs without any recoating. The PEG-NH(2) modified chip provided a fast, reproducible, efficient MCE separation of proteins with a wide variety of isoelectric points within 15s. Furthermore, the application of the modified chip to affinity electrophoresis using bovine serum albumin gave a good chiral separation of amino acids. PMID:20678876

  3. Lab-on-a-robot: integrated microchip CE, power supply, electrochemical detector, wireless unit, and mobile platform.

    PubMed

    Berg, Christopher; Valdez, David C; Bergeron, Phillip; Mora, Maria F; Garcia, Carlos D; Ayon, Arturo

    2008-12-01

    In this paper, the fabrication of a wireless mobile unit containing an electrochemical detection module and a 3-channel high-voltage power supply (HVPS) designed for microchip CE is described. The presented device consists of wireless global positioning system controlled robotics, an electrochemical detector utilizing signal conditioning analog circuitry and a digital feedback range controller, a HVPS, an air pump, and a CE microchip. A graphical user interface (LabVIEW) was also designed to communicate wirelessly with the device, from a distant personal computer communication port. The entire device is integrated and controlled by digital hardware implemented on a field programmable gate array development board. This lab-on-a-robot is able to navigate to a global position location, acquire an air sample, perform the analysis (injection, separation, and detection), and send the data (electropherogram) to a remote station without exposing the analyst to the testing environment. PMID:19130571

  4. Coating Process

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A black chrome coating, originally developed for spacecraft solar cells, led to the development of an efficient flat plate solar collector. The coating, called Chromonyx, helps the collector absorb more heat. Olympic Solar Corporation was formed to electroplate the collector. The coating technique allows 95% of the sun's energy to be utilized. The process is widely used.

  5. Intensity noise properties of Nd:YVO 4 microchip lasers pumped with an amplitude squeezed diode laser

    NASA Astrophysics Data System (ADS)

    Becher, C.; Boller, K.-J.

    1998-02-01

    We report on intensity noise measurements of single-frequency Nd:YVO 4 microchip lasers optically pumped with amplitude squeezed light from an injection-locked diode laser. Calibrated homodyne measurements show a minimum intensity noise of 10.1 dB above the SQL at a frequency of 100 kHz. The measured intensity noise spectra are described with high accuracy by a theoretical model based on the quantum mechanical Langevin rate equations, including classical and quantum noise sources.

  6. Low temperature epoxy-free and flux-less bonding process applied to solid-state microchip laser

    NASA Astrophysics Data System (ADS)

    Kopp, Christophe; Gilbert, Karen

    2005-06-01

    Epoxy free bonding is decisive to improve reliability of optoelectronic devices using active components such as laser diode. Therefore soldering is usually preferred as bonding technology but it often needs components metallizing, heating over 140°C and liquid or gas fluxing which may let some corrosive residues. Thus soldering cannot be widely used on optical microchip components. Working on solid-state microchip laser bonding in a project called NANOPACK supported by the French research ministry, we have developed low temperature epoxy free bonding technology. The microchip laser is bonded onto a submount by thermocompression at low temperature and moderate relative pressure using an indium foil to form the adhesive joint. This technology uses both a unique property of indium to wet and to bond to certain non-metallics such as glass, quartz, and various metallic oxides, and fluxless soldering of indium with gold by solid-state interdiffusion bonding or solid-liquid interdiffusion bonding. This way, mean bond strength about 300g/mm2 has been obtained for 2mg chip with very good resistance to thermal aging. This epoxy free technology offers a real alternative for bonding non-metallic components which cannot stand usual soldering processes. Moreover, as it is a fluxless process, this technology is very attractive to hermetically seal lids under controlled atmosphere.

  7. Multiple-point electrochemical detection for a dual-channel hybrid PDMS-glass microchip electrophoresis device.

    PubMed

    Castaño-Alvarez, Mario; Fernández-la-Villa, Ana; Pozo-Ayuso, Diego F; Fernández-Abedul, María Teresa; Costa-García, Agustín

    2009-10-01

    A new PDMS-based dual-channel MCE with multiple-point amperometric detection has been evaluated. Electrophoresis has been optimised in a single-channel device. Pretreatment with 0.1 M NaOH is very important for increasing and stabilising the EOF. The precision is adequate for a day's work in terms of both peak current and migration time. The RSD of the peak current for five successive signals was 1.9, 2.4 and 3.1% for dopamine, p-aminophenol and hydroquinone. RSD for the migration time was always less than 1.3%, which demonstrates the stability of the EOF and the possibility of running multiple experiments in the same microchip. The adequate inter-microchip precision as well as the rapid and simple manufacturing procedure indicates the disposable nature of the PDMS microchips. A dual-channel device with very simple multiple-point amperometric detection is proposed here. Elasticity of the PDMS allows removing the polymer slightly and aligning gold wires working electrodes. Injection can be performed from each of the sample reservoirs or from both simultaneously. The distance between the separation channels is critical for obtaining adequate signals as well as the introduction of a high-voltage electrode in the buffer reservoir. Simultaneous measurement of the same analytes in both channels is possible by applying the same potential. Moreover, since no cross-separation is produced, different analytes or samples can be simultaneously measured. PMID:19802849

  8. High-power Yb:YAG/YAG microchip laser using octagonal-shape waveguide with uniform absorbed power distribution

    NASA Astrophysics Data System (ADS)

    Radmard, S.; Haghparast, A.; Arabgari, S.; Mehrabani, M. T.

    2013-06-01

    An innovative architecture for edge-pumped high power microchip laser is introduced. This geometry consists of a Yb:YAG thin disk gain media surrounded by an irregular octagonal undoped YAG cap as pumping light waveguide. The main advantages of the new geometry are high uniform absorption distribution, high absorption efficiency and simple construction to fabricate. Using the Monte Carlo ray tracing method, the pumping process and absorption profile in active medium are simulated. In addition, considering the impact of Yb+3 doping concentration and temperature on thermal conductivity, and based on the finite-difference method the conduction equation was solved and the temperature distribution in the gain media calculated. Based on these simulations, influence of active medium parameters such as core diameter, doping concentration and octagon side sizes ratio on absorption profile and efficiency as well as maximum temperature in gain medium is investigated. High absorption efficiency (over 94%) with perfect top-hat absorption profile has been predicted to be obtained from the designed microchip with optimized parameters. This microchip has a core diameter of 4 or 5 mm, 9 at% Yb3+ doping concentration and 300 μm thickness. An estimation based on laser rate equations shows that with 960 W pumping power, more than 600 W output power (optical efficiency of 66%) can be extracted from the designed system.

  9. Metal Coatings

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During the Apollo Program, General Magnaplate Corporation developed process techniques for bonding dry lubricant coatings to space metals. The coatings were not susceptible to outgassing and offered enhanced surface hardness and superior resistance to corrosion and wear. This development was necessary because conventional lubrication processes were inadequate for lightweight materials used in Apollo components. General Magnaplate built on the original technology and became a leader in development of high performance metallurgical surface enhancement coatings - "synergistic" coatings, - which are used in applications from pizza making to laser manufacture. Each of the coatings is designed to protect a specific metal or group of metals to solve problems encountered under operating conditions.

  10. SURFACE PROPERTIES AND FOULING RELEASE BEHAVIOR OF POLY(DIMETHYLSILOXANE) NETWORKS

    EPA Science Inventory

    This research is aimed toward developing coatings which have minimally adhesive surfaces with respect to attachment of marine organisms. These "fouling release" coatings are of interest to the Navy from environmental and economic standpoint. The development of nontoxic (i.e. non-...

  11. Solution processed polydimethylsiloxane/gold nanostar flexible substrates for plasmonic sensing

    NASA Astrophysics Data System (ADS)

    Shiohara, Amane; Langer, Judith; Polavarapu, Lakshminarayana; Liz-Marzán, Luis M.

    2014-07-01

    Gold nanostars can display tunable optical properties in the visible and near IR, which lead to strong electromagnetic field enhancement at their tips. We report generalized application of gold nanostars for ultrasensitive identification of molecules, based on both localized surface plasmon resonance (LSPR) and surface enhanced Raman scattering (SERS). We address the requirements of plasmonic sensors, related to sufficiently large areas where nanoparticles are uniformly immobilized with high density, as well as mechanical flexibility, which offers additional advantages for real-world applications. Gold nanostar monolayers were thus immobilized on transparent, flexible polydimethylsiloxane substrates, and their refractive index sensitivity and SERS performance were studied. The application of such substrates for LSPR based molecular sensing is demonstrated via detection of a model analyte, mercaptoundecanoic acid. We further demonstrate SERS-based pesticide detection on fruit skin, by simply covering the fruit surface with the flexible plasmonic substrate, at the area where the target molecule is to be detected. The transparency of the substrate allows SERS detection through backside excitation, thereby facilitating practical implementation.Gold nanostars can display tunable optical properties in the visible and near IR, which lead to strong electromagnetic field enhancement at their tips. We report generalized application of gold nanostars for ultrasensitive identification of molecules, based on both localized surface plasmon resonance (LSPR) and surface enhanced Raman scattering (SERS). We address the requirements of plasmonic sensors, related to sufficiently large areas where nanoparticles are uniformly immobilized with high density, as well as mechanical flexibility, which offers additional advantages for real-world applications. Gold nanostar monolayers were thus immobilized on transparent, flexible polydimethylsiloxane substrates, and their refractive index

  12. Calculating the permeability coefficients of mixed matrix membranes of polydimethylsiloxane and silicalite crystals to various ethanol-water solutions using molecular simulations.

    EPA Science Inventory

    The permeability coefficients of mixed matrix membranes of polydimethylsiloxane (PDMS) and silicalite crystal are taken as the sum of the permeability coefficients of membrane components each weighted by their associated mass fraction. The permeability coefficient of a membrane c...

  13. Integration of cell phone imaging with microchip ELISA to detect ovarian cancer HE4 biomarker in urine at the point-of-care.

    PubMed

    Wang, Shuqi; Zhao, Xiaohu; Khimji, Imran; Akbas, Ragip; Qiu, Weiliang; Edwards, Dale; Cramer, Daniel W; Ye, Bin; Demirci, Utkan

    2011-10-21

    Ovarian cancer is asymptomatic in the early stages and most patients present with advanced levels of disease. The lack of cost-effective methods that can achieve frequent, simple and non-invasive testing hinders early detection and causes high mortality in ovarian cancer patients. Here, we report a simple and inexpensive microchip ELISA-based detection module that employs a portable detection system, i.e., a cell phone/charge-coupled device (CCD) to quantify an ovarian cancer biomarker, HE4, in urine. Integration of a mobile application with a cell phone enabled immediate processing of microchip ELISA results, which eliminated the need for a bulky, expensive spectrophotometer. The HE4 level detected by a cell phone or a lensless CCD system was significantly elevated in urine samples from cancer patients (n = 19) than healthy controls (n = 20) (p < 0.001). Receiver operating characteristic (ROC) analyses showed that the microchip ELISA coupled with a cell phone running an automated analysis mobile application had a sensitivity of 89.5% at a specificity of 90%. Under the same specificity, the microchip ELISA coupled with a CCD had a sensitivity of 84.2%. In conclusion, integration of microchip ELISA with cell phone/CCD-based colorimetric measurement technology can be used to detect HE4 biomarker at the point-of-care (POC), paving the way to create bedside technologies for diagnostics and treatment monitoring. PMID:21881677

  14. TECHNICAL NOTE: Chemical bonding of multiwalled carbon nanotubes to polydimethylsiloxanes and modification of the photoinitiator system for microstereolithography processing

    NASA Astrophysics Data System (ADS)

    Zhang, Nanyan; Xie, Jining; Guers, Manton; Varadan, Vijay K.

    2004-02-01

    Oxidized multiwalled carbon nanotubes (CNT) were functionalized with polydimethylsiloxanes (PDMS) by opening epoxide groups of PDMS under ultrasonic irradiation and the acidic condition provided by ion-exchange resin. The final product is a uniform solution and allowed the wet-casting of thin film. Photoinitiator and sensitizer were added for UV curing using the Penn state microstereolithography (MSL) system which has a wavelength close to 364 nm.

  15. Micropatterned Culture and Differentiation of Human Bone Marrow Mesenchymal Stem Cells Using a Polydimethylsiloxane Microstencil.

    PubMed

    Choi, Jin Ho; Bae, Jae-Sung; Lee, Hyun; Jin, Hee Kyung; Kim, Gyu Man

    2016-02-01

    A method for fabrication of polydimethylsiloxane (PDMS) microstencils was developed and its application to localized culture of human bone marrow mesenchymal stem cells (hMSCs) was tested. Unlike conventional culture methods, which culture cells on an entire surface, microscale cell culture provides precise control of the size and shape of stem cell patterns, and minimizes consumption of cells and culture media. A PDMS microstencil was fabricated by PDMS casting using an SU-8 mold prepared by photolithography. A pattern of 500-µm dots was tested. For the test, a PDMS microstencil was placed on a glass disk and cells were seeded on the stencil at a density of 5 x 10⁴ cells/cm². The hMSCs were cultured for 2 days at 37 °C in a humidified 5% CO2 atmosphere. The PDMS microstencil was removed after 2 days and the hMSC patterns were inspected under a microscope. The results confirmed that stem cells can be cultured using a PDMS microstencil. The micropatterned hMSCs retained their ability to differentiate into osteogenic and adipogenic cells. Thus, using a PDMS microstencil, stem cells can be cultured and differentiated in micropatterns in a precisely controlled manner, in any shape and size, for research and bioengineering applications. PMID:27305770

  16. Micropatterning of neural stem cells and Purkinje neurons using a polydimethylsiloxane (PDMS) stencil.

    PubMed

    Choi, Jin Ho; Lee, Hyun; Jin, Hee Kyung; Bae, Jae-sung; Kim, Gyu Man

    2012-12-01

    A new fabrication method of a polydimethylsiloxane (PDMS) stencil embedded microwell plate is proposed and applied to a localized culture of Purkinje neurons (PNs) and neural stem cells (NSCs). A microwell plate combines a PDMS stencil and well plate. The PDMS stencil was fabricated by spin casting from an SU-8 master mold. Gas blowing using nitrogen was adopted to perforate the stencil membrane. An acrylic well plate compartment mold was fabricated using computer numerical control (CNC) machining. By PDMS casting using a stencil placed on an acrylic mold, microwell plates were fabricated without punching or the use of a plasma bonding process. By using the stencil as a physical mask for the cell culture, PNs and NSCs were successfully cultured into micropatterns. The microwell plate could be applied to the localizing and culturing of a cell. The micropatterned NSCs were differentiated into neurons, astrocytes, and oligodendrocytes. The results showed that cells could be cultured and differentiated into micropatterns in a precisely controlled manner in any shape and in specific sizes for bioscience study and bioengineering applications. PMID:23042549

  17. Long-term reduction in poly(dimethylsiloxane) surface hydrophobicity via cold-plasma treatments.

    PubMed

    Larson, B J; Gillmor, S D; Braun, J M; Cruz-Barba, L E; Savage, D E; Denes, F S; Lagally, M G

    2013-10-22

    Poly(dimethylsiloxane), PDMS, a versatile elastomer, is the polymer of choice for microfluidic systems. It is inexpensive, relatively easy to pattern, and permeable to oxygen. Unmodified PDMS is highly hydrophobic. It is typically exposed to an oxygen plasma to reduce this hydrophobicity. Unfortunately, the PDMS surface soon returns to its original hydrophobic state. We present two alternative plasma treatments that yield long-term modification of the wetting properties of a PDMS surface. An oxygen plasma pretreatment followed by exposure to a SiCl4 plasma and an oxygen-CCl4 mixture plasma both cause a permanent reduction in the hydrophobicity of the PDMS surface. We investigate the properties of the plasma-treated surfaces with X-ray photoelectron spectroscopy (XPS) and contact angle measurements. We propose that the plasma treated PDMS surface is a dynamic mosaic of high- and low-contact-angle functionalities. The SiCl4 and CCl4 plasmas attach polar groups that block coverage of the surface by low-molecular-weight groups that exist in PDMS. We describe an application that benefits from these new plasma treatments, the use of a PDMS stencil to form dense arrays of DNA on a surface. PMID:24063604

  18. Development of Polydimethylsiloxane Substrates with Tunable Elastic Modulus to Study Cell Mechanobiology in Muscle and Nerve

    PubMed Central

    Palchesko, Rachelle N.; Zhang, Ling; Sun, Yan; Feinberg, Adam W.

    2012-01-01

    Mechanics is an important component in the regulation of cell shape, proliferation, migration and differentiation during normal homeostasis and disease states. Biomaterials that match the elastic modulus of soft tissues have been effective for studying this cell mechanobiology, but improvements are needed in order to investigate a wider range of physicochemical properties in a controlled manner. We hypothesized that polydimethylsiloxane (PDMS) blends could be used as the basis of a tunable system where the elastic modulus could be adjusted to match most types of soft tissue. To test this we formulated blends of two commercially available PDMS types, Sylgard 527 and Sylgard 184, which enabled us to fabricate substrates with an elastic modulus anywhere from 5 kPa up to 1.72 MPa. This is a three order-of-magnitude range of tunability, exceeding what is possible with other hydrogel and PDMS systems. Uniquely, the elastic modulus can be controlled independently of other materials properties including surface roughness, surface energy and the ability to functionalize the surface by protein adsorption and microcontact printing. For biological validation, PC12 (neuronal inducible-pheochromocytoma cell line) and C2C12 (muscle cell line) were used to demonstrate that these PDMS formulations support cell attachment and growth and that these substrates can be used to probe the mechanosensitivity of various cellular processes including neurite extension and muscle differentiation. PMID:23240031

  19. Polydimethylsiloxane-fabricated optical fiber sensor capable of measuring both large axial and shear strain

    NASA Astrophysics Data System (ADS)

    Shen, Yu; Wang, Ziyuan; Wen, Huaihai; Zhou, Zhi

    2014-11-01

    Fiber optic sensor (FOS) has received much attention in the field of Structure Health Monitoring (SHM) due to its advantages of low weight, small size, high sensitivity multiplexing ability, free of electromagnetic interference and long durability. However, in harsh environments, structures often undergo large strain where few traditional fiber optic sensors could survive. This paper report a novel material with features of light-transparent, chemically inert, thermally stable material Polydimethylsiloxane(PDMS) fabricated large axial/shearing strain sensor. The sensor was fabricated by directly coupling a conventional signal mode fiber into half cured PDMS material using a translation stage under the inspection of a microscope. Meanwhile, a laser diode and a photo detector were used in the fabrication process to make sure the sensor achieved minimum light loss. An experiment was conducted later to investigate the sensor's transmission characteristic in 1310nm infrared laser relating with the applied axial/shearing strain. The results show that the proposed sensor survived an axial strain of 6 7.79 x 106 μɛ ; a shear of 4 6.49 x 104 μɛ with good linearity and repetition. The experiment indicates that the proposed sensor can potentially be used as strain sensing elements in Structure Health Monitoring systems under earthquake or explosion.

  20. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    PubMed Central

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-01-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient ‘green technique’, gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm−2h−1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry. PMID:25819091

  1. Disposable parallel poly(dimethylsiloxane) microbioreactor with integrated readout grid for germination screening of Aspergillus ochraceus.

    PubMed

    Demming, S; Sommer, B; Llobera, A; Rasch, D; Krull, R; Büttgenbach, S

    2011-01-01

    In this work a disposable, parallel microbioreactor (MBR) suitable for screening in batch or continuous mode is presented. The reactor consists of five parallel microchambers made of poly(dimethylsiloxane) bonded to a glass substrate. A grid structure is engraved on each chamber, allowing subsequent morphology imaging. Measurements are recorded over the entire cultivation period with constant parameters, namely, position and focus in the z-axis. The microdevice may be used for either parallel, uni- or multiparametric screening, and overcomes the drawback of gridless microwell plates which require expensive equipment such as an inverted microscope with an automatic stage. To validate the scalability from laboratory scale to microscale, and thus the cultivation protocol in the MBR, the germination of fungal spores (A. ochraceus) is evaluated for two different key magnitudes (pH and temperature) and compared to the results obtained from conventional laboratory scale systems (flasks and agar plates). Information on germination capacity with regard to interspecies' variability allows for optimization of industrial processes as optimal pH and temperature matched to the mesoscopic cultivation systems. The germination conditions therefore remain unaffected inside the MBR, while providing the following advantages: (i) dramatic reduction of medium consumption, (ii) submerged cultivation with constant oxygen supply, (iii) assured low cost and disposability, and (iv) possibility of a continuous cultivation mode. PMID:21423594

  2. Robust and Stable Transparent Superhydrophobic Polydimethylsiloxane Films by Duplicating via a Femtosecond Laser-Ablated Template.

    PubMed

    Gong, Dingwei; Long, Jiangyou; Jiang, Dafa; Fan, Peixun; Zhang, Hongjun; Li, Lin; Zhong, Minlin

    2016-07-13

    Realizing superhydrophobicity, high transparency on polydimethylsiloxane (PDMS) surface enlarges its application fields. We applied a femtosecond laser to fabricate well-designed structures combining microgrooves with microholes array on mirror finished stainless steel to form a template. Then liquid PDMS was charged for the duplicating process to introduce a particular structure composed of a microwalls array with a certain distance between each other and a microprotrusion positioned at the center of a plate surrounded by microwalls. The parameters such as the side length of microwalls and the height of a microcone were optimized to achieve required superhydrophobicity at the same time as high-transparency properties. The PDMS surfaces show superhydrophobicity with a static contact angle of up to 154.5 ± 1.7° and sliding angle lower to 6 ± 0.5°, also with a transparency over 91%, a loss less than 1% compared with plat PDMS by the measured light wavelength in the visible light scale. The friction robust over 100 cycles by sandpaper, strong light stability by 8 times density treatment, and thermal stability up to 325 °C of superhydrophobic PDMS surface was investigated. We report here a convenient and efficient duplicating method, being capable to form a transparent PDMS surface with superhydrophobicity in mass production, which shows extensive application potentials. PMID:27320020

  3. Controlled mud-crack patterning and self-organized cracking of polydimethylsiloxane elastomer surfaces

    PubMed Central

    Seghir, Rian; Arscott, Steve

    2015-01-01

    Exploiting pattern formation – such as that observed in nature – in the context of micro/nanotechnology could have great benefits if coupled with the traditional top-down lithographic approach. Here, we demonstrate an original and simple method to produce unique, localized and controllable self-organised patterns on elastomeric films. A thin, brittle silica-like crust is formed on the surface of polydimethylsiloxane (PDMS) using oxygen plasma. This crust is subsequently cracked via the deposition of a thin metal film – having residual tensile stress. The density of the mud-crack patterns depends on the plasma dose and on the metal thickness. The mud-crack patterning can be controlled depending on the thickness and shape of the metallization – ultimately leading to regularly spaced cracks and/or metal mesa structures. Such patterning of the cracks indicates a level of self-organization in the structuring and layout of the features – arrived at simply by imposing metallization boundaries in proximity to each other, separated by a distance of the order of the critical dimension of the pattern size apparent in the large surface mud-crack patterns. PMID:26437880

  4. Functionalization of polydimethylsiloxane membranes to be used in the production of voice prostheses

    NASA Astrophysics Data System (ADS)

    Ferreira, Paula; Carvalho, Álvaro; Ruivo Correia, Tiago; Paiva Antunes, Bernardo; Joaquim Correia, Ilídio; Alves, Patrícia

    2013-10-01

    The voice is produced by the vibration of vocal cords which are located in the larynx. Therefore, one of the major consequences for patients subjected to laryngectomy is losing their voice. In these cases, a synthetic one-way valve set (voice prosthesis) can be implanted in order to allow restoration of speech. Most voice prostheses are produced with silicone-based materials such as polydimethylsiloxane (PDMS). This material has excellent properties, such as optical transparency, chemical and biological inertness, non-toxicity, permeability to gases and excellent mechanical resistance that are fundamental for its application in the biomedical field. However, PDMS is very hydrophobic and this property causes protein adsorption which is followed by microbial adhesion and biofilm formation. To overcome these problems, surface modification of materials has been proposed in this study. A commercial silicone elastomer, SylgardTM 184 was used to prepare membranes whose surface was modified by grafting 2-hydroxyethylmethacrylate and methacrylic acid by low-pressure plasma treatment. The hydrophilicity, hydrophobic recovery and surface energy of the produced materials were determined. Furthermore, the cytotoxicity and antibacterial activity of the materials were also assessed. The results obtained revealed that the PDMS surface modification performed did not affect the material's biocompatibility, but decreased their hydrophobic character and bacterial adhesion and growth on its surface.

  5. Enhanced pervaporative desulfurization by polydimethylsiloxane membranes embedded with silver/silica core-shell microspheres.

    PubMed

    Cao, Ruijian; Zhang, Xiongfei; Wu, Hong; Wang, Jingtao; Liu, Xiaofei; Jiang, Zhongyi

    2011-03-15

    Pervaporative desulfurization based on membrane technology provides a promising alternative for removal of sulfur substances (as represented by thiophene) in fluid catalytic cracking (FCC) gasoline. The present study focused on the performance enhancement of polydimethylsiloxane (PDMS) membrane by incorporation of core-shell structured silver/silica microspheres. A silane coupling agent, N-[3-(trimethoxysily)propyl]-ethylenediamine (TSD), was used to chelate the Ag(+) via its amino groups and attach the silver seeds onto the silica surface via condensation of its methoxyl groups. The resultant microspheres were characterized by Zeta-positron annihilation lifetime spectroscopy (ZetaPALS), inductively coupled plasmaoptical emission spectrophotometer (ICP), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Ag(+)/SiO(2)-PDMS composite membranes were prepared by blending PDMS with the as-synthesized silver/silica microspheres. PALS analysis was used to correlate the apparent fractional free volume with permeation flux. The sorption selectivity towards thiophene was enhanced after incorporation of silver/silica microspheres due to the π-complexation between the silver on the microsphere surface and the thiophene molecules. The pervaporative desulfurization performance of the composite membrane was investigated using thiophene/n-octane mixture as a model gasoline. The composite membrane exhibited an optimum desulfurization performance with a permeation flux of 7.76 kg/(m(2)h) and an enrichment factor of 4.3 at the doping content of 5%. PMID:21288638

  6. Polydimethylsiloxane embedded mouse aorta ex vivo perfusion model: proof-of-concept study focusing on atherosclerosis

    NASA Astrophysics Data System (ADS)

    Wang, Xueya; Wolf, Marc P.; Keel, Rahel Bänziger; Lehner, Roman; Hunziker, Patrick R.

    2012-07-01

    Existing mouse artery ex vivo perfusion models have utilized arteries such as carotid, uterine, and mesenteric arteries, but not the aorta. However, the aorta is the principal vessel analyzed for atherosclerosis studies in vivo. We have devised a mouse aorta ex vivo perfusion model that can bridge this gap. Aortas from apoE(-/-) mice are embedded in a transparent, gas-permeable, and elastic polymer matrix [polydimethylsiloxane (PDMS)] and artificially perfused with cell culture medium under cell culture conditions. After 24 h of artificial ex vivo perfusion, no evidence of cellular apoptosis is detected. Utilizing a standard confocal microscope, it is possible to image specific receptor targeting of cells in atherosclerotic plaques during 24 h. Imaging motion artifacts are minimal due to the polymer matrix embedding. Re-embedding of the aorta enables tissue sectioning and immuno-histochemical analysis. The ex vivo data are validated by comparison with in vivo experiments. This model can save animal lives via production of multiple endpoints in a single experiment, is easy to apply, and enables straightforward comparability with pre-existing atherosclerosis in vivo data. It is suited to investigate atherosclerotic disease in particular and vascular biology in general.

  7. All-Polymer Electrolytic Tilt Sensor with Conductive Poly(dimethylsiloxane) Electrodes

    NASA Astrophysics Data System (ADS)

    Kyoo Lee, June; Choi, Ju Chan; Kong, Seong Ho

    2013-06-01

    In this study, an all-polymer electrolytic tilt sensor with conductive and corrosion-resistant poly(dimethylsiloxane) (PDMS) electrodes was designed and its performances were characterized. A PDMS cavity in the sensor for holding an electrolyte was fabricated by soft lithography using an ultraviolet-sensitive polymer. A conductive PDMS composite (gPDMS) with graphite powder was used for the electrode to measure the inclination angle of the electrolyte. A gPDMS composite with a graphite concentration above 40 wt % was able to function as a conductive polymer. The fabricated all-polymer tilt sensor exhibited a detectable inclination range of +/-60° and showed a relatively linear output signal compared with those exhibited by conventional micromachined tilt sensors with axis asymmetrical cavities. The maximum hysteresis of the output signal was approximately 0.1 Vrms when the sensor repeatedly tilted and leveled off. In addition to the fundamental characterization of the sensor, various characteristics of the all-polymer tilt sensor, such as time-dependent and electrolyte-volume-dependent variations in the output signal, were investigated in this study. While the performance of the proposed sensor was comparable to that of conventional silicon-micromachined tilt sensors, the sensor could be produced at a fraction of the cost required to fabricate the conventional sensors.

  8. All-Polymer Electrolytic Tilt Sensor with Conductive Poly(dimethylsiloxane) Electrodes

    NASA Astrophysics Data System (ADS)

    Lee, June Kyoo; Choi, Ju Chan; Kong, Seong Ho

    2013-06-01

    In this study, an all-polymer electrolytic tilt sensor with conductive and corrosion-resistant poly(dimethylsiloxane) (PDMS) electrodes was designed and its performances were characterized. A PDMS cavity in the sensor for holding an electrolyte was fabricated by soft lithography using an ultraviolet-sensitive polymer. A conductive PDMS composite (gPDMS) with graphite powder was used for the electrode to measure the inclination angle of the electrolyte. A gPDMS composite with a graphite concentration above 40 wt % was able to function as a conductive polymer. The fabricated all-polymer tilt sensor exhibited a detectable inclination range of ± 60° and showed a relatively linear output signal compared with those exhibited by conventional micromachined tilt sensors with axis asymmetrical cavities. The maximum hysteresis of the output signal was approximately 0.1 V\\text{rms when the sensor repeatedly tilted and leveled off. In addition to the fundamental characterization of the sensor, various characteristics of the all-polymer tilt sensor, such as time-dependent and electrolyte-volume-dependent variations in the output signal, were investigated in this study. While the performance of the proposed sensor was comparable to that of conventional silicon-micromachined tilt sensors, the sensor could be produced at a fraction of the cost required to fabricate the conventional sensors.

  9. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    NASA Astrophysics Data System (ADS)

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-03-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient `green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm-2h-1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry.

  10. Long-term characterization of neural electrodes based on parylene-caulked polydimethylsiloxane substrate.

    PubMed

    Jeong, Jinmo; Chou, Namsun; Kim, Sohee

    2016-06-01

    This study investigates the mechanical and long-term electrical properties of parylene-caulked polydimethylsiloxane (PDMS) as a substrate for implantable electrodes. The parylene-caulked PDMS is a structure where particles of parylene fill the porous surface of PDMS. This material is expected to have low water absorption and desirable mechanical properties such as flexibility and elasticity that are beneficial in many biomedical applications. To evaluate the mechanical property and electrical stability of parylene-caulked PDMS for potential in-vivo uses, tensile tests were conducted firstly, which results showed that the mechanical strength of parylene-caulked PDMS was comparable to that of native PDMS. Next, surface electrodes based on parylene-caulked PDMS were fabricated and their impedance was measured in phosphate-buffered saline (PBS) solution at 36.5 °C over seven months. The electrodes based on parylene-caulked PDMS exhibited the improved stability in impedance over time than native PDMS. Thus, with improved electrical stability in wet environment and preserved mechanical properties of PDMS, the electrodes based on parylene-caulked PDMS are expected to be suitable for long-term in-vivo applications. PMID:27165102

  11. Fabrication of Refractive Index Tunable Polydimethylsiloxane Photonic Crystal for Biosensor Application

    NASA Astrophysics Data System (ADS)

    Raman, Karthik; Murthy, T. R. Srinivasa; Hegde, G. M.

    Photonic crystal based nanostructures are expected to play a significant role in next generation nanophotonic devices. Recent developments in two-dimensional (2D) photonic crystal based devices have created widespread interest as such planar photonic structures are compatible with conventional microelectronic and photonic devices. Various optical components such as waveguides, resonators, modulators and demultiplexers have been designed and fabricated based on 2D photonic crystal geometry. This paper presents the fabrication of refractive index tunable Polydimethylsiloxane (PDMS) polymer based photonic crystals. The advantages of using PDMS are mainly its chemical stability, bio-compatibility and the stack reduces sidewall roughness scattering. The PDMS structure with square lattice was fabricated by using silicon substrate patterned with SU8-2002 resist. The 600 nm period grating of PDMS is then fabricated using Nano-imprinting. In addition, the refractive index of PDMS is modified using certain additive materials. The resulting photonic crystals are suitable for application in photonic integrated circuits and biological applications such as filters, cavities or microlaser waveguides.

  12. Studies of directed adhesion of bio-organisms on functionalized polydimethylsiloxane elastomer

    NASA Astrophysics Data System (ADS)

    Estes, Thomas G.

    This research involves the adhesion of organisms and cells to polydimethylsiloxane elastomer (PDMSe). This research is accomplished while incorporating surface modification of PDMSe. The surface properties of interest for this research are elastic modulus, chemistry and topography. Organisms that have been studied are Balanus amphitrite barnacles, Ulva spores, Bugula neritina bryozoans, human umbilical vein endothelial cells (HUVECs) and fibroblasts. Applications of this work are focused on preventing the accumulation of spores and barnacles on the hulls of boats, longer lasting synthetic vascular grafts and new diagnostic methods for cardiovascular disease. Currently, organisms on the sides of ship hulls are responsible for increased fuel consumption, increased pollution and greenhouse gasses and increased costs of cleaning. The current paint used saves $3 billion world wide, but is toxic to the environment. This approach is making use of a non toxic surface, PDMSe. PDMSe is modified and then subjected to settlement and release assays in order to further understand the mechanisms that may prevent biofouling. Cardiovascular disease is the leading cause of death in the United States. This research also involves ways to diagnose and prevent cardiovascular disease through investigation of adhesion of the cells that line the inside of our blood vessels. This is accomplished through chemistries to specifically bind endothelial cells to PDMSe. Once this has been accomplished, the cells may be counted and correlated to specific cardiovascular diseases.

  13. Structural and physical properties of Ag doped poly(dimethylsiloxane) modified silica xerogels

    NASA Astrophysics Data System (ADS)

    Chakrabarti, K.; Whang, C. M.

    2001-12-01

    The purpose of the present work is to study the effect of silver (Ag) incorporation on the structural and physical properties of poly(dimethylsiloxane) (PDMS) modified silica xerogels. PDMS was chosen as the organic component because of its similarity of backbone structure (-Si-O-) with tetraethyl orthosilicate, the inorganic component of organically modified silicates. In the present work silver was incorporated by two routes: (i) directly in the sol and (ii) silver doping was done after preformed porous matrix was obtained. The microstructures, particle size distribution, infrared spectra, and optical coloration have been studied. The utility of two methods has been discussed. It was found that the particle size was much smaller compared with that of classical gels with dispersed Ag particles. For the indirect method of silver doping the particle size distribution was found to follow log-normal distribution function. Upon exposure to humid air the samples change optical state from transparency to opacity. However, this was found to be reversible when treated above 300 °C. This phenomenon may be utilized to fabricate humidity sensor and optical switches.

  14. Bubble generation and mechanism in polydimethylsiloxane based polymerase chain reaction chip

    NASA Astrophysics Data System (ADS)

    Chen, Jingdong; Chen, Di; Xie, Yao; Chen, Xiang; Wang, Kan; Cui, Daxiang; Du, Hangxiang; Wang, Zhigang

    2015-02-01

    In order to explain the mechanism of bubble generation in polydimethylsiloxane (PDMS), we investigated the crucial factors: the surface wettability and permeability of PDMS. Two microfluidic chips were designed and fabricated: a PDMS/glass chip and a glass/PDMS/glass sandwich chip (about 1 μm in thickness of PDMS). Then, two sets of experiments were carried out: a comparison between the PDMS/glass chips untreated and treated with O2 plasma, and another comparison between a PDMS/glass chip and a glass/PDMS/glass sandwich chip. The bubble in the PDMS/glass chip was avoided by treating with O2 plasma. After the treatment, the residual gas between the PDMS surface and water was eliminated in that the PDMS surface became hydrophilic. In addition, the gas molecules required higher energy to enter the chambers due to the reduced contact angle of PDMS and water. The glass/PDMS/glass sandwich chip was treated with the vacuum processing to eliminate the residual gas. And the gas outside of the chip did not enter the chambers through the thin layer of PDMS easily. This further verified that the surface wettability and the permeability of PDMS can result in the bubble generation.

  15. Poly(dimethylsiloxane) microlens array integrated with microfluidic channel for fluorescence spectroscopy detection

    NASA Astrophysics Data System (ADS)

    Rujihan, Suparat; Damrongsak, Badin; Kittidachachan, Pattareeya

    2013-06-01

    Fluorescence spectroscopy detection has been commonly used in chemical and biochemical applications as it provides a good reliability and high sensitivity. Commercially available fluorescence spectroscopy system is typically bulky and expensive, hence making it inconvenience for on-site measurement which requires portable systems. However, the drawback of small devices is that it has a low detection volume, resulting in low fluorescence signal. In this paper, we report a microfluidic channel implemented with a microlens array for enhancing the performance of fluorescence spectroscopy detection. The microlens array was used to focus an excitation light onto the microchannel, thus expecting the increase in fluorescence detection signal. Both microchannels and microlens arrays were individually fabricated from poly-dimethylsiloxane (PDMS) using low-cost printed-circuit-board master molds. The fabrication and characterization of PDMS-based microlens arrays are discussed. In short, the microlens in plano-convex shape was designed with diameters of 700, 800 and 900 microns. The fabricated microlens arrays were characterized for radius of curvatures, SAGs and focal lengths. The plano-convex microlens array was then integrated into a microfluidic system in order to investigate the overall performance of fluorescence spectroscopy detection. Experiments were conducted with two fluorescence dyes, i.e. Rhodamine 6G and Coumarin 153. The preliminary results revealed that the PDMS microlens array implemented on the designed system shows potential for improving excitation and emission light intensity and, as a consequence, signal to background ratio of the fluorescence spectroscopy detection.

  16. Elastic poly(ε-caprolactone)-polydimethylsiloxane copolymer fibers with shape memory effect for bone tissue engineering.

    PubMed

    Kai, Dan; Prabhakaran, Molamma P; Yu Chan, Benjamin Qi; Liow, Sing Shy; Ramakrishna, Seeram; Xu, Fujian; Loh, Xian Jun

    2016-02-01

    A porous shape memory scaffold with biomimetic architecture is highly promising for bone tissue engineering applications. In this study, a series of new shape memory polyurethanes consisting of organic poly(ε-caprolactone) (PCL) segments and inorganic polydimethylsiloxane (PDMS) segments in different ratios (9 : 1, 8 : 2 and 7 : 3) was synthesised. These PCL-PDMS copolymers were further engineered into porous fibrous scaffolds by electrospinning. With different ratios of PCL: PDMS, the fibers showed various fiber diameters, thermal behaviour and mechanical properties. Even after being processed into fibrous structures, these PCL-PDMS copolymers maintained their shape memory properties, and all the fibers exhibited excellent shape recovery ratios of  >90% and shape fixity ratios of  >92% after 7 thermo-mechanical cycles. Biological assay results corroborated that the fibrous PCL-PDMS scaffolds were biocompatible by promoting osteoblast proliferation, functionally enhanced biomineralization-relevant alkaline phosphatase expression and mineral deposition. Our study demonstrated that the PCL-PDMS fibers with excellent shape memory properties are promising substrates as bioengineered grafts for bone regeneration. PMID:26836757

  17. Patterning Poly(dimethylsiloxane) Microspheres via Combination of Oxygen Plasma Exposure and Solvent Treatment.

    PubMed

    Li, Qiaoyuan; Han, Xue; Hou, Jing; Yin, Jian; Jiang, Shichun; Lu, Conghua

    2015-10-22

    Here a simple low-cost yet robust route has been developed to prepare poly(dimethylsiloxane) (PDMS) microspheres with various surface wrinkle patterns. First, the aqueous-phase-synthesized PDMS microspheres are exposed to oxygen plasma (OP), yielding the oxidized SiOx layer and the corresponding stiff shell/compliant core system. The subsequent solvent swelling and solvent evaporation induce the spontaneous formation of a series of curvature and overstress-sensitive spherical wrinkles such as dimples, short rodlike depressions, and herringbone and labyrinth patterns. The effects of the experimental parameters, including the radius and Young's modulus of the microspheres, the OP exposure duration, and the nature of the solvents, on these tunable spherical wrinkles have been systematically studied. The experimental results reveal that a power-law dependence of the wrinkling wavelength on the microsphere radius exists. Furthermore, the induced wrinkling patterns are inherently characteristic of a memory effect and good reversibility. Meanwhile, the corresponding phase diagram of the wrinkle morphologies on the spherical surfaces vs the normalized radius of curvature and the excess swelling degree has been demonstrated. It is envisioned that the introduced strategy in principle could be applied to other curved surfaces for expeditious generation of well-defined wrinkle morphologies, which not only enables the fabrication of solids with multifunctional surface properties, but also provides important implications for the morphogenesis in soft materials and tissues. PMID:26435184

  18. Systematic Investigation of the Mechanical and Surface Properties of Poly(dimethylsiloxane) Networks

    NASA Astrophysics Data System (ADS)

    Melillo, Matthew; Klein, Zoe; Walker, Edwin; Genzer, Jan

    2015-03-01

    Poly(dimethylsiloxane) (PDMS) is one of the most common elastomers. Its applications range broadly from medical devices to absorbents for water treatment, and recently it has seen rapid growth in the use of microfluidic devices. Despite extensive research and characterization of PDMS networks, the static water contact angles of these elastomers reported in the literature range broadly from a low near 90 degrees upwards to greater than 120 degrees. To investigate this large gap in reported surface properties, we have systematically studied the effects of polymer molecular weight, degree of tetra-functional crosslinker loading, end-group chemical functionality, and the extent of dilution of the curing mixture on the mechanical and surface properties of end-linked PDMS networks. The gel and sol fractions, mechanical properties, and water contact angles have been shown to vary greatly based on the aforementioned variables. This study provides insight to the factors that contribute to such a wide range of surface properties reported in the literature. Furthermore, these results demonstrate the need to fully and carefully consider the manner and environment in which PDMS networks are formed when preparing them for specific applications.

  19. An equipment-free polydimethylsiloxane microfluidic spotter for fabrication of microarrays

    PubMed Central

    Tang, Teng; Li, Gang; Jia, Chunping; Gao, Kunpeng; Zhao, Jianlong

    2014-01-01

    This paper presents a low-cost, power-free, and easy-to-use spotter system for fabrication of microarrays. The spotter system uses embedded dispensing microchannels combined with a polydimethylsiloxane (PDMS) membrane containing regular arrays of well-defined thru-holes to produce precise, uniform DNA or protein microarrays for disease diagnosis or drug screening. Powered by pre-evacuation of its PDMS substrate, the spotter system does not require any additional components or external equipment for its operation, which can potentially allow low-cost, high-quality microarray fabrication by minimally trained individuals. Polyvinylpyrrolidone was used to modify the PDMS surface to prevent protein adsorption by the microchannels. Experimental results indicate that the PDMS spotter shows excellent printing performance for immobilizing proteins. The measured coefficient of variation (CV) of the diameter of 48 spots was 2.63% and that of the intensity within one array was 2.87%. Concentration gradient experiments revealed the superiority of the immobilization density of the PDMS spotter over the conventional pin-printing method. Overall, this low-cost, power-free, and easy-to-use spotting system provides an attractive new method to fabricate microarrays. PMID:24803969

  20. A multilayer poly(dimethylsiloxane) electrospray ionization emitter for sample injection and online mass spectrometric detection.

    PubMed

    Iannacone, Jamie M; Jakubowski, Jennifer A; Bohn, Paul W; Sweedler, Jonathan V

    2005-12-01

    An ESI emitter made of poly(dimethylsiloxane) interfaces on-chip sample preparation with MS detection. The unique multilayer design allows both the analyte and the spray solutions to reside on the device simultaneously in discrete microfluidic environments that are spatially separated by a polycarbonate track-etched, nanocapillary array membrane (NCAM). In direct spray mode, voltage is applied to the microchannel containing a spray solution delivered via a syringe pump. For injection, the spray potential is lowered and a voltage is applied that forward biases the membrane and permits the analyte to enter the spray channel. Once the injection is complete, the bias potential is switched off, and the spray voltage is increased to generate the ESI of the injected analyte plug. Consecutive injections of a 10 microM bovine insulin solution are reproducible and produce sample plugs with limited band broadening and high quality mass spectra. Peptide signals are observed following transport through the NCAM, even when the peptide is dissolved in solutions containing up to 20% seawater. The multilayer emitter shows great potential for performing multidimensional chemical manipulations on-chip, followed by direct ESI with negligible dead volume for online MS analysis. PMID:16278909

  1. Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane substrate

    SciTech Connect

    Chou, Namsun; Lee, Jongho; Kim, Sohee

    2014-12-15

    This paper describes a reliable fabrication method of stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate. The electrode traces and pads were formed in out-of-plane structures to improve the flexibility and stretchability of the electrode array. The suspended traces and pads were attached to the PDMS substrate via parylene posts that were located nearby the traces and under the pads. As only conventional micro-electro-mechanical systems techniques were used, the out-of-plane electrode arrays were clearly fabricated at wafer level with high yield and reliability. Also, bi-layer out-of-plane electrodes were formed through additional fabrication steps in addition to mono-layer out-of-plane electrodes. The mechanical characteristics such as the stretchability, flexibility, and foldability of the fabricated electrodes were evaluated, resulting in stable electrical connection of the metal traces with up to 32.4% strain and up to 360° twist angle over 25 mm. The durability in stretched condition was validated by cyclic stretch test with 10% and 20% strain, resulting in electrical disconnection at 8600 cycles when subjected to 20% strain. From these results, it is concluded that the proposed fabrication method produced highly reliable, out-of-plane and stretchable electrodes, which would be used in various flexible and stretchable electronics applications.

  2. Improving acoustic streaming effects in fluidic systems by matching SU-8 and polydimethylsiloxane layers.

    PubMed

    Catarino, S O; Minas, G; Miranda, J M

    2016-07-01

    This paper reports the use of acoustic waves for promoting and improving streaming in tridimensional polymethylmethacrylate (PMMA) cuvettes of 15mm width×14mm height×2.5mm thickness. The acoustic waves are generated by a 28μm thick poly(vinylidene fluoride) - PVDF - piezoelectric transducer in its β phase, actuated at its resonance frequency: 40MHz. The acoustic transmission properties of two materials - SU-8 and polydimethylsiloxane (PDMS) - were numerically compared. It was concluded that PDMS inhibits, while SU-8 allows, the transmission of the acoustic waves to the propagation medium. Therefore, by simulating the acoustic transmission properties of different materials, it is possible to preview the acoustic behavior in the fluidic system, which allows the optimization of the best layout design, saving costs and time. This work also presents a comparison between numerical and experimental results of acoustic streaming obtained with that β-PVDF transducer in the movement and in the formation of fluid recirculation in tridimensional closed domains. Differences between the numerical and experimental results are credited to the high sensitivity of acoustic streaming to the experimental conditions and to limitations of the numerical method. The reported study contributes for the improvement of simulation models that can be extremely useful for predicting the acoustic effects of new materials in fluidic devices, as well as for optimizing the transducers and matching layers positioning in a fluidic structure. PMID:27044029

  3. Molding a silver nanoparticle template on polydimethylsiloxane to efficiently capture mammalian cells.

    PubMed

    Bai, Hai-Jing; Gou, Hong-Lei; Xu, Jing-Juan; Chen, Hong-Yuan

    2010-02-16

    Herein, a functional template made up of in situ synthesized silver nanoparticles (AgNPs) is prepared on polydimethylsiloxane (PDMS) for the spatial control of cell capture, where the residual Si-H groups in the PDMS matrix are used as reductants to reduce AgNO(3) for forming AgNPs. In virtue of microfluidic system, a one-dimensional array pattern of AgNPs is obtained easily. Further combining with plasma treatment, a two-dimensional array pattern of AgNPs could be achieved. The obtained PDMS-AgNPs composite is characterized in detail. The PDMS-AgNPs composite shows good antibacterial property in E. coli adhesion tests. The patterns possess hifi and high resolution (ca. 8 microm). Cell patterns with high efficiency and spatial selectivity are further formed with the aid of H-Arg-Gly-Asp-Cys-OH (RGDC) tetrapeptide which is grafted on the AgNPs template. Cells immobilized on the template show a good ability for adhesion, spreading, migration, and growth. PMID:20141218

  4. A novel surface modification technique for forming porous polymer monoliths in poly(dimethylsiloxane)

    PubMed Central

    Burke, Jeffrey M.; Smela, Elisabeth

    2012-01-01

    A new method of surface modification is described for enabling the in situ formation of homogenous porous polymer monoliths (PPMs) within poly(dimethylsiloxane) (PDMS) microfluidic channels that uses 365 nm UV illumination for polymerization. Porous polymer monolith formation in PDMS can be challenging because PDMS readily absorbs the monomers and solvents, changing the final monolith morphology, and because PDMS absorbs oxygen, which inhibits free-radical polymerization. The new approach is based on sequentially absorbing a non-hydrogen-abstracting photoinitiator and the monomers methyl methacrylate and ethylene diacrylate within the walls of the microchannel, and then polymerizing the surface treatment polymer within the PDMS, entangled with it but not covalently bound. Four different monolith compositions were tested, all of which yielded monoliths that were securely anchored and could withstand pressures exceeding the bonding strength of PDMS (40 psi) without dislodging. One was a recipe that was optimized to give a larger average pore size, required for low back pressure. This monolith was used to concentrate and subsequently mechanical lyse B lymphocytes. PMID:22685511

  5. Photoacoustic microscopy based on polydimethylsiloxane thin film Fabry-Perot optical interferometer

    NASA Astrophysics Data System (ADS)

    Park, Soongho; Eom, Jonghyun; Shin, Jun Geun; Rim, Sunghwan; Lee, Byeong Ha

    2016-03-01

    We present a photoacoustic microscopy (PAM) system based on a Fabry-Perot Interferometer (FPI) consisting of a transparent Polydimethylsiloxane (PDMS) thin film. Most of the PAM systems have limitations with the system alignment because the ultrasound transducers for detection are not transparent. Therefore, the excitation laser source should avoid the opaque transducer to illuminate the sample, which makes the system difficult to build-up. Especially, the system volume is highly limited to be compact. In our experiment, to solve these difficulties, a FPI based on the PDMS film has been implemented and applied to measure the acoustic wave signal. The system uses a FPI as an acoustic wave detector instead of a conventional ultrasound transducer. A tunable laser was used to choose the quadrature-point at which the signal has the highly sensitve and linear response to the acoustic wave. Also a 20Hz pulsed Nd:YAG laser was used to generate acoustic waves from a sample. When the acoustic waves arrive at the PDMS film, one of the surfaces of the film is modulated at the detecting point, which gives the tuned FPI interference signal. From the signal arriving time, the depth location of the sample is calculated. As a primary experiment using the PDMS thin film as an ultrasound transducer, a couple of narrow black friction tapes located in a water container were used as the samples. This proposed imaging method can be used in various applications for the detection and measurement of acoustic waves.

  6. Fabrication of three-dimensional microfluidic systems by stacking molded polydimethylsiloxane (PDMS) layers

    NASA Astrophysics Data System (ADS)

    Jo, Byung-Ho; Beebe, David J.

    1999-08-01

    A new technique to fabricate 3D microchannels using polydimethylsiloxane (PDMS) elastomer material is presented. The process allows for the stacking of many thin (about 100 micrometers thick) patterned PDMS layers to realize complex 3D channel paths. Replica molding method is utilized to generate each layer. The master for each layer is formed on a silicon wafer using SU-8 positive relief photoresist. PDMS is cast against the master producing molded layers containing channels and openings. To realize thin layers with openings, a sandwich molding configuration was developed that allows precise control of the PDMS thickness. The master wafer is clamped within a sandwich that includes flat aluminum plates, a flexible polyester film layer, a rigid Pyrex wafer and a rubber sheet. A parametric study is performed on PDMS surface activation in a reactive ion etching (RIE) system and the subsequent methanol treatment for bonding and aligning very thin individual components to a substrate. Low RF power and short treatment times are better than high RF power and long treatment times respectively for instant bonding. Layer to layer alignment of less than 15 micrometers is achieved with manual alignment techniques that utilize surface tension driven self alignment methods. A coring procedure is used to realize off chip fluidic connections via the bottom PDMS layer, allowing the top layer to remain smooth and flat for complete optical access. After fabricating 3D channel paths, the hydrophobic surfaces of the inside channel walls can be activated (hydrophobic to hydrophilic) an oxygen plasma RIE system.

  7. A polymeric master replication technology for mass fabrication of poly(dimethylsiloxane) microfluidic devices.

    PubMed

    Li, Hai-Fang; Lin, Jin-Ming; Su, Rong-Guo; Cai, Zong Wei; Uchiyama, Katsumi

    2005-05-01

    A protocol of producing multiple polymeric masters from an original glass master mold has been developed, which enables the production of multiple poly(dimethylsiloxane) (PDMS)-based microfluidic devices in a low-cost and efficient manner. Standard wet-etching techniques were used to fabricate an original glass master with negative features, from which more than 50 polymethylmethacrylate (PMMA) positive replica masters were rapidly created using the thermal printing technique. The time to replicate each PMMA master was as short as 20 min. The PMMA replica masters have excellent structural features and could be used to cast PDMS devices for many times. An integration geometry designed for laser-induced fluorescence (LIF) detection, which contains normal deep microfluidic channels and a much deeper optical fiber channel, was successfully transferred into PDMS devices. The positive relief on seven PMMA replica masters is replicated with regard to the negative original glass master, with a depth average variation of 0.89% for 26-microm deep microfluidic channels and 1.16% for the 90 mum deep fiber channel. The imprinted positive relief in PMMA from master-to-master is reproducible with relative standard deviations (RSDs) of 1.06% for the maximum width and 0.46% for depth in terms of the separation channel. The PDMS devices fabricated from the PMMA replica masters were characterized and applied to the separation of a fluorescein isothiocyanate (FITC)-labeled epinephrine sample. PMID:15812838

  8. Measuring interactions between polydimethylsiloxane and serum proteins at the air-water interface.

    PubMed

    Liao, Zhengzheng; Hsieh, Wan-Ting; Baumgart, Tobias; Dmochowski, Ivan J

    2013-07-30

    The interaction between synthetic polymers and proteins at interfaces is relevant to basic science as well as a wide range of applications in biotechnology and medicine. One particularly common and important interface is the air-water interface (AWI). Due to the special energetics and dynamics of molecules at the AWI, the interplay between synthetic polymer and protein can be very different from that in bulk solution. In this paper, we applied the Langmuir-Blodgett technique and fluorescence microscopy to investigate how the compression state of polydimethylsiloxane (PDMS) film at the AWI affects the subsequent adsorption of serum protein [e.g., human serum albumin (HSA) or immunoglobulin G (IgG)] and the interaction between PDMS and protein. Of particular note is our observation of circular PDMS domains with micrometer diameters that form at the AWI in the highly compressed state of the surface film: proteins were shown to adsorb preferentially to the surface of these circular PDMS domains, accompanied by a greater than 4-fold increase in protein found in the interfacial film. The PDMS-only film and the PDMS-IgG composite film were transferred to cover glass, and platinum-carbon replicas of the transferred films were further characterized by scanning electron microscopy and atomic force microscopy. We conclude that the structure of the PDMS film greatly affects the amount and distribution of protein at the interface. PMID:23819833

  9. Development of a rapid cure polydimethylsiloxane replication process with near-zero shrinkage

    NASA Astrophysics Data System (ADS)

    Badshah, Mohsin Ali; Jang, Hyungjun; Kim, Young Kyu; Kim, Tae-Hyoung; Kim, Seok-min

    2014-07-01

    Replicated polydimethylsiloxane (PDMS) micro/nanostructures are widely used in various research fields due to their inexpensiveness, flexibility, low surface energy, good optical properties, biocompatibility, chemical inertness, high durability, and easy fabrication process. However, the application of PDMS micro/nanostructures is limited when an accurate pattern shape or position is required because of the shrinkage that occurs during the PDMS curing process. In this study, we analyzed the effects of processing parameters in the PDMS replication process on the shrinkage of the final structure. Although the shrinkage can be decreased by decreasing the curing temperature, this reduction also increases the unnecessary curing time. To minimize the inherent shrinkage in the PDMS replica without an accompanying curing time increase, we propose a PDMS replication process on a high modulus substrate (glass and polymer films) with compression pressure, in which the adhesion force between the substrate and the PDMS, and the compression pressure prevent shrinkage during the curing process. Using the proposed method, a PDMS replica with less than 0.1% in-plane and vertical shrinkage was obtained at a curing temperature of 150°C and a curing time of 10 min.

  10. Novel anti-flooding poly(dimethylsiloxane) (PDMS) catalyst binder for microbial fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Chen, Guang; Hickner, Michael A.; Logan, Bruce E.

    2012-11-01

    Poly(dimethylsiloxane) (PDMS) was investigated as an alternative to Nafion as an air cathode catalyst binder in microbial fuel cells (MFCs). Cathodes were constructed around either stainless steel (SS) mesh or copper mesh using PDMS as both catalyst binder and diffusion layer, and compared to cathodes of the same structure having a Nafion binder. With PDMS binder, copper mesh cathodes produced a maximum power of 1710 ± 1 mW m-2, while SS mesh had a slightly lower power of 1680 ± 12 mW m-2, with both values comparable to those obtained with Nafion binder. Cathodes with PDMS binder had stable power production of 1510 ± 22 mW m-2 (copper) and 1480 ± 56 mW m-2 (SS) over 15 days at cycle 15, compared to a 40% decrease in power with the Nafion binder. Cathodes with the PDMS binder had lower total cathode impedance than those with Nafion. This is due to a large decrease in diffusion resistance, because hydrophobic PDMS effectively prevented catalyst sites from filling up with water, improving oxygen mass transfer. The cost of PDMS is only 0.23% of that of Nafion. These results showed that PDMS is a very effective and low-cost alternative to Nafion binder that will be useful for large scale construction of these cathodes for MFC applications.

  11. Polydimethylsiloxane microfluidic chemiluminescence immunodevice with the signal amplification strategy for sensitive detection of human immunoglobin G.

    PubMed

    Li, Huifang; Zhao, Mei; Liu, Wei; Chu, Weiru; Guo, Yumei

    2016-01-15

    A polydimethylsiloxane (PDMS) microfluidic chemiluminescence (CL) immunodevice for sensitive detection of human immunoglobin G (IgG) with the signal amplification strategy was developed in this work. The immunodevice was prepared by covalently immobilizing capture antibodies (Abs) on the silanized microchannel of microfluidic chip. Gold nanoparticles (AuNPs) functionalized with a high molar ratio of horseradish peroxidase (HRP) were used as an Ab label for signal amplification. Using a sandwich immunoassay, the multi-HRP conjugated AuNPs can catalyze the luminol-H2O2 CL system to achieve the high sensitivity. In addition, the double spiral flow-channel was adopted here, which can still contribute to the high sensitivity. Based on signal amplification strategy, the performance of human IgG tests revealed a lower detection limit (DL) of 0.03ng/mL and showed an increase of 7.4-fold in detection sensitivity compared to a commercial Ab-HRP conjugation. This microfluidic immunodevice can provide an alternative approach for sensitive detection of human IgG in the field of clinic diagnostic and therapeutic. PMID:26592629

  12. Structure and properties of thermoplastic polyurethanes based on poly(dimethylsiloxane): assessment of biocompatibility.

    PubMed

    Pergal, Marija V; Nestorov, Jelena; Tovilović, Gordana; Ostojić, Sanja; Gođevac, Dejan; Vasiljević-Radović, Dana; Djonlagić, Jasna

    2014-11-01

    Properties and biocompatibility of a series of thermoplastic poly(urethane-siloxane)s (TPUSs) based on α,ω-dihydroxy ethoxy propyl poly(dimethylsiloxane) (PDMS) for potential biomedical application were studied. Thin films of TPUSs with a different PDMS soft segment content were characterized by (1) H NMR, quantitative (13) C NMR, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), contact angle, and water absorption measurements. Different techniques (FTIR, AFM, and DMA) showed that decrease of PDMS content promotes microphase separation in TPUSs. Samples with a higher PDMS content have more hydrophobic surface and better waterproof performances, but lower degree of crystallinity. Biocompatibility of TPUSs was examined after attachment of endothelial cells to the untreated copolymer surface or surface pretreated with multicomponent protein mixture, and by using competitive protein adsorption assay. TPUSs did not exhibit any cytotoxicity toward endothelial cells, as measured by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assays. The untreated and proteins preadsorbed TPUS samples favored endothelial cells adhesion and growth, indicating good biocompatibility. All TPUSs adsorbed more albumin than fibrinogen in competitive protein adsorption experiment, which is feature regarded as beneficial for biocompatibility. The results indicate that TPUSs have good surface, thermo-mechanical, and biocompatible properties, which can be tailored for biomedical application requirements by adequate selection of the soft/hard segments ratio of the copolymers. PMID:24376027

  13. The Role of Polydimethylsiloxane in the Molecular Structure of Silica Xerogels Intended for Drug Carriers

    PubMed Central

    Czarnobaj, Katarzyna

    2015-01-01

    The aim of this study was to prepare and examine polymer/oxide xerogels with metronidazole (MT) as delivery systems for the local application of a drug to a bone. The nanoporous SiO2-CaO and PDMS-modified SiO2-CaO xerogel materials with different amounts of the polymer, polydimethylsiloxane (PDMS), were prepared by the sol-gel method. Characterization assays comprised the analysis of the composite materials by using Fourier transform infrared spectroscopy (FTIR), determining the specific surface area of solids (BET), using X-ray powder diffraction (XRD) and scanning electron microscope (SEM) techniques, and further monitoring in the ultraviolet and visible light regions (UV-Vis) of the in vitro release of the drug (metronidazole) over time. According to these results, the bioactive character and chemical stability of PDMS-modified silica xerogels have been proven. The release of MT from xerogels was strongly correlated with the composition of the matrix. In comparison with the pure oxide matrix, PDMS-modified matrices accelerated the release of the drug through its bigger pores, and additionally, on account of weaker interactions with the drug. The obtained results for the xerogel composites suggest that the metronidazole-loaded xerogels could be promising candidates for formulations in local delivery systems particularly to bone. PMID:26839836

  14. Gold nanoparticle-polydimethylsiloxane films reflect light internally by optical diffraction and Mie scattering

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    Optical properties of polymer films embedded with plasmonic nanoparticles (NPs) are important in many implementations. In this work, optical extinction by polydimethylsiloxane (PDMS) films containing gold (Au) NPs was enhanced at resonance compared to AuNPs in suspensions, Beer-Lambert law, or Mie theory by internal reflection due to optical diffraction in 16 nm AuNP-PDMS films and Mie scattering in 76 nm AuNP-PDMS films. Resonant extinction per AuNP for 16 nm AuNPs with negligible resonant Mie scattering was enhanced up to 1.5-fold at interparticle separation (i.e., Wigner-Seitz radii) comparable to incident wavelength. It was attributable to diffraction through apertures formed by overlapping electric fields of adjacent, resonantly excited AuNPs at Wigner-Seitz radii equal to or less than incident wavelengths. Resonant extinction per AuNP for strongly Mie scattering 76 nm AuNPs was enhanced up to 1.3-fold at Wigner-Seitz radii four or more times greater than incident wavelength. Enhanced light trapping from diffraction and/or scattering is relevant to optoelectronic, biomedical, and catalytic activity of substrates embedded with NPs.

  15. Stretchability of Silver Films on Thin Acid-Etched Rough Polydimethylsiloxane Substrates Fabricated by Electrospray Deposition

    NASA Astrophysics Data System (ADS)

    Mehdi, S. M.; Cho, K. H.; Kang, C. N.; Choi, K. H.

    2015-07-01

    This paper investigates the fabrication of Ag films through the electrospray deposition (ESD) technique on sub-millimeter-thick acid-etched rough polydimethylsiloxane (PDMS) substrates having both low and high modulus of elasticity. The main focus of the study is on the stretchable behavior of ESD-deposited Ag nanoparticles-based thin films on these substrates when subjected to axial strains. Experimental results suggest that the as-fabricated films on thin acid-etched rough low modulus PDMS has an average stretchability of 5.6% with an average increase in the resistance that is 23 times that of the initial resistance at electrical failure (complete rupture of the films). Comparatively, the stretchability of Ag films on the high modulus PDMS was found to be 3 times higher with 4.65 times increase in the resistance at electrical failure. Also, a high positive value of the piezoresistive coefficient for these films suggests that the resistivity changes during stretching, and thus deviation from the simplified models is inevitable. Based on these results, new models are presented that quantify the changes in resistance with strain.

  16. Low-cost formation of bulk and localized polymer-derived carbon nanodomains from polydimethylsiloxane

    PubMed Central

    Alcántara, Juan Carlos Castro; Cerda Zorrilla, Mariana; Cabriales, Lucia; Rossano, Luis Manuel León

    2015-01-01

    Summary We present two simple alternative methods to form polymer-derived carbon nanodomains in a controlled fashion and at low cost, using custom-made chemical vapour deposition and selective laser ablation with a commercial CD-DVD platform. Both processes presented shiny and dark residual materials after the polymer combustion and according to micro-Raman spectroscopy of the domains, graphitic nanocrystals and carbon nanotubes have successfully been produced by the combustion of polydimethylsiloxane layers. The fabrication processes and characterization of the byproduct materials are reported. We demonstrate that CVD led to bulk production of graphitic nanocrystals and single-walled carbon nanotubes while direct laser ablation may be employed for the formation of localized fluorescent nanodots. In the latter case, graphitic nanodomains and multi-wall carbon nanotubes are left inside microchannels and preliminary results seem to indicate that laser ablation could offer a tuning control of the nature and optical properties of the nanodomains that are left inside micropatterns with on-demand geometries. These low-cost methods look particularly promising for the formation of carbon nanoresidues with controlled properties and in applications where high integration is desired. PMID:25977844

  17. A carbon nanotube filled polydimethylsiloxane hybrid membrane for enhanced butanol recovery

    PubMed Central

    Xue, Chuang; Du, Guang-Qing; Chen, Li-Jie; Ren, Jian-Gang; Sun, Jian-Xin; Bai, Feng-Wu; Yang, Shang-Tian

    2014-01-01

    The carbon nanotubes (CNTs) filled polydimethylsiloxane (PDMS) hybrid membrane was fabricated to evaluate its potential for butanol recovery from acetone-butanol-ethanol (ABE) fermentation broth. Compared with the homogeneous PDMS membrane, the CNTs filled into the PDMS membrane were beneficial for the improvement of butanol recovery in butanol flux and separation factor. The CNTs acting as sorption-active sites with super hydrophobicity could give an alternative route for mass transport through the inner tubes or along the smooth surface. The maximum total flux and butanol separation factor reached up to 244.3 g/m2·h and 32.9, respectively, when the PDMS membrane filled with 10 wt% CNTs was used to separate butanol from the butanol/water solution at 80°C. In addition, the butanol flux and separation factor increased dramatically as temperature increased from 30°C to 80°C in feed solution since the higher temperature produced more free volumes in polymer chains to facilitate butanol permeation. A similar increase was also observed when butanol titer in solution increased from 10 g/L to 25 g/L. Overall, the CNTs/PDMS hybrid membrane with higher butanol flux and selectivity should have good potential for pervaporation separation of butanol from ABE fermentation broth. PMID:25081019

  18. Wavefront Kinetics of Plamsa Oxidation of Polydimethylsiloxane: Implications for Micropatterning Size Limits by Wrinkling

    NASA Astrophysics Data System (ADS)

    Bayley, Angus; Cabral, Joao; Lingling Liao, Joanne; Chiche, Arnaud; Stavrinou, Paul

    2013-03-01

    We investigate spontaneous wrinkling of bilayers under compressive strain as a means of producing highly ordered micropatterns that span macroscopic areas. Our focus is a fast track wrinkling method, involving plasma oxidation of pre-stretched elastomeric polydimethylsiloxane (PDMS), which when subsequently relaxed forms one-dimensionally aligned sinusoidal surface undulations. For the first time, we evaluate this micropatterning method in terms of the range of geometries of 1D wrinkles it can produce. Our investigation reveals the presence of an apparent minimum wrinkling wavelength for a given value of prestrain (approximately 600nm for a prestrain of 10%), offering clues regarding the kinetics of glassy film formation on the surface of PDMS during plasma oxidation, which is subsequently investigated. X-ray reflectometry and analysis of wrinkling behavior for a selection of PDMS samples exposed to a range of plasma doses yields evidence that this transient film growth process is not dissimilar to the process of frontal photopolymerization. With the benefit of this finding, a route to further minimization of wrinkle periodicity - increasing processing pre-strain - is identified and subsequently implemented, allowing us to access periodicities as low as 140nm. We acknowledge the EPSRC for their funding of this work.

  19. Photooxidation of plasma polymerized polydimethylsiloxane film by 172 nm vacuum ultraviolet light irradiation in dilute oxygen

    NASA Astrophysics Data System (ADS)

    Ichikawa, S.

    2006-08-01

    Plasma polymerized polydimethylsiloxane films irradiated under different partial pressures of oxygen with a 172nm vacuum ultraviolet light were investigated in order to clarify the roles of molecular oxygen and photons in photooxidation. The thickness, densities, surface roughness, elemental compositions, and molecular structures of the irradiated and unirradiated films were examined by using glazing incidence x-ray reflectivity, Rutherford backscattering, infrared, and x-ray absorption (XAS) spectroscopies. Photooxidation is hardly promoted by irradiation in a high vacuum of 1×10-4Pa, though photodesorption of the methyl group and formation of Si-H bonds were observed. Silica films thicker than 140nm were formed at room temperature by irradiating them in low pressure oxygen gases. The degree of oxidation was smaller for the oxygen pressure of 10kPa than for 83Pa. Si K-edge XAS was performed to clarify the change of coordination environment of silicon by photooxidation in dilute oxygen flow containing less than 5ppm of molecular oxygen.

  20. Enhanced performance in capacitive force sensors using carbon nanotube/polydimethylsiloxane nanocomposites with high dielectric properties.

    PubMed

    Jang, Hyeyoung; Yoon, Hyungsuk; Ko, Youngpyo; Choi, Jaeyoo; Lee, Sang-Soo; Jeon, Insu; Kim, Jong-Ho; Kim, Heesuk

    2016-03-14

    Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased dielectric properties of elastomers and simple sensor structure. We rationally design dielectric elastomers based on alkylamine modified-multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composites, which have a higher dielectric constant than pure PDMS. The alkylamine-MWCNTs show excellent dispersion in a PDMS matrix, thus leading to enhanced and reliable dielectric properties of the composites. A force sensor array fabricated with alkylamine-MWCNT/PDMS composites presents an enhanced response due to the higher dielectric constant of the composites than that of pure PDMS. This study is the first to report enhanced performance of capacitive force sensors by modulating the dielectric properties of elastomers. We believe that the disclosed strategy to improve the sensor performance by increasing the dielectric properties of elastomers has great potential in the development of capacitive force sensor arrays that respond to various input forces. PMID:26899884

  1. Biomimetic phosphorylcholine polymer grafting from polydimethylsiloxane surface using photo-induced polymerization.

    PubMed

    Goda, Tatsuro; Konno, Tomohiro; Takai, Madoka; Moro, Toru; Ishihara, Kazuhiko

    2006-10-01

    The biomimetic synthetic phospholipid polymer containing a phosphorylcholine group, 2-methacryloyloxyethyl phosphorylcholine (MPC), has improved the surface property of biomaterials. Both hydrophilic and anti-biofouling surfaces were prepared on polydimethylsiloxane (PDMS) with MPC grafted by surface-initiated photo-induced radical polymerization. Benzophenone was used as the photoinitiator. The quantity of the adsorbed initiator on PDMS was determined by UV absorption and ellipsometry. The poly(MPC)-grafted PDMS surfaces were characterized by XPS, ATR-FTIR and static water contact angle (SCA) measurements. The SCA on PDMS decreased from 115 degrees to 25 degrees after the poly(MPC) grafting. The in vitro single protein adsorption on the poly(MPC)-grafted PDMS decreased 50-75% compared to the unmodified PDMS. The surface friction of the poly(MPC)-grafted PDMS was lower than the unmodified PDMS under wet conditions. The oxygen permeability of the poly(MPC)-grafted PDMS was as high as the unmodified PDMS. The tensile property of PDMS was maintained at about 90% of the ultimate stress and strain after the poly(MPC) grafting. The surface-modified PDMS is expected to be a novel medical elastomer which possesses an excellent surface hydrophilicity, anti-biofouling property, oxygen permeability and tensile property. PMID:16797692

  2. NMR observation of the swelling process of polydimethylsiloxane networks. Average orientational order of monomeric units

    NASA Astrophysics Data System (ADS)

    Cohen-Addad, J. P.; Domard, M.; Herz, J.

    1982-03-01

    The swelling process of several polydimethylsiloxane gels was observed from the relaxation process of the magnetization transverse component of protons bound to elementary chains. Polymeric gels were studied in equilibrium with solvent vapor, using chloroform. A model of progressive swelling process from the dry gel to the equilibrium with pure solvent liquid is proposed from observed elementary chain properties. At small swelling degrees, gels behave like strongly entangled chains in concentrated solutions; then, elementary chains are desinterspersed and a packing condition may be applied from a characteristic swelling degree to equilibrium swelling. In this concentration range, gels swollen by different solvents behave the same way at a given swelling degree. Trapped entanglements are perceived. All these properties are derived from residual dipolar interactions associated with average orientational order of monomeric units induced by chain elongation. This residual energy is shown to be proportional to (r/N)2, with r the end-to-end vector and N the number of links of a chain. The C theorem proposed by De Gennes is extended to NMR properties. It is clearly shown that NMR observed on a chain segment may be sensitive to both its overall dimensions (30 Å) and its internal isomerization properties.

  3. Controlled mud-crack patterning and self-organized cracking of polydimethylsiloxane elastomer surfaces

    NASA Astrophysics Data System (ADS)

    Seghir, Rian; Arscott, Steve

    2015-10-01

    Exploiting pattern formation - such as that observed in nature - in the context of micro/nanotechnology could have great benefits if coupled with the traditional top-down lithographic approach. Here, we demonstrate an original and simple method to produce unique, localized and controllable self-organised patterns on elastomeric films. A thin, brittle silica-like crust is formed on the surface of polydimethylsiloxane (PDMS) using oxygen plasma. This crust is subsequently cracked via the deposition of a thin metal film - having residual tensile stress. The density of the mud-crack patterns depends on the plasma dose and on the metal thickness. The mud-crack patterning can be controlled depending on the thickness and shape of the metallization - ultimately leading to regularly spaced cracks and/or metal mesa structures. Such patterning of the cracks indicates a level of self-organization in the structuring and layout of the features - arrived at simply by imposing metallization boundaries in proximity to each other, separated by a distance of the order of the critical dimension of the pattern size apparent in the large surface mud-crack patterns.

  4. A dynamically modified microfluidic poly(dimethylsiloxane) chip with electrochemical detection for biological analysis.

    PubMed

    Dou, Yue-Hua; Bao, Ning; Xu, Jing-Juan; Chen, Hong-Yuan

    2002-10-01

    Separation and direct detection of amino acids, glucose and peptide in a 3.1 cm separation channel made of poly(dimethylsiloxane) (PDMS) with end-column amperometric detection at a copper microdisk electrode was developed. This system is the integration of a normal sized working electrode with electrochemical detection on a PDMS microfabricated device. The PDMS channels dynamically modified by 2-morpholinoethanesulfonic acid (MES) show less adsorption and more enhanced efficiency than that of unmodified ones when applied to separations of these biological molecules. The migration time is less than 100 s and the reproducibility of migration time is satisfactory with relative standard deviation (RSD) of 2.8% in 19 successive injections. The limits of detection of arginine (Arg), glucose, and methionine-glycine (Met-Gly) are estimated to be 2.0, 8.5, and 64.0 microM at S/N = 3, approximately 0.5-16.0 fmol, respectively. Variances influencing the separation efficiency and amperometric response, including injection, separation voltage, detection potential, or concentration of buffer and additive, are assessed and optimized. PMID:12412125

  5. The Deformation of Polydimethylsiloxane (PDMS) Microfluidic Channels Filled with Embedded Circular Obstacles under Certain Circumstances.

    PubMed

    Roh, Changhyun; Lee, Jaewoong; Kang, Chankyu

    2016-01-01

    Experimental investigations were conducted to determine the influence of polydimethylsiloxane (PDMS) microfluidic channels containing aligned circular obstacles (with diameters of 172 µm and 132 µm) on the flow velocity and pressure drop under steady-state flow conditions. A significant PDMS bulging was observed when the fluid flow initially contacted the obstacles, but this phenomenon decreased in the 1 mm length of the microfluidic channels when the flow reached a steady-state. This implies that a microfluidic device operating with steady-state flows does not provide fully reliable information, even though less PDMS bulging is observed compared to quasi steady-state flow. Numerical analysis of PDMS bulging using ANSYS Workbench showed a relatively good agreement with the measured data. To verify the influence of PDMS bulging on the pressure drop and flow velocity, theoretical analyses were performed and the results were compared with the experimental results. The measured flow velocity and pressure drop data relatively matched well with the classical prediction under certain circumstances. However, discrepancies were generated and became worse as the microfluidic devices were operated under the following conditions: (1) restricted geometry of the microfluidic channels (i.e., shallow channel height, large diameter of obstacles and a short microchannel length); (2) operation in quasi-steady state flow; (3) increasing flow rates; and (4) decreasing amount of curing agent in the PDMS mixture. Therefore, in order to obtain reliable data a microfluidic device must be operated under appropriate conditions. PMID:27322239

  6. Fabrication of microlens arrays by a rolling process with soft polydimethylsiloxane molds

    NASA Astrophysics Data System (ADS)

    Hu, Chia-Nying; Hsieh, Hsin-Ta; Su, Guo-Dung John

    2011-06-01

    In this paper, we present a new roll-to-roll method to fabricate visible light transparent microlens arrays on a glass substrate by using soft and cost-effective polydimethylsiloxane (PDMS) molds. First, we fabricated microlens array master molds by photoresist thermal reflow processes on silicon substrates. We then transferred the pattern to PDMS molds by a spin coater. After making the PDMS molds, we used a two-wheel roll-to-roll printing machine to replicate ultraviolet resin microlens arrays on glass substrates. The PDMS molds can be made easily at a low cost compared with traditional electroplating metal molds. We studied the quality of microlens arrays that were replicated by different rolling pressures of 20, 200 and 500 N cm-2. We also identified the relation between the pressure and the shape of the microlens arrays. The results showed that the best yield rate and replication performance were achieved with a pressure of approximately 200 N cm-2 and 4 min of ultraviolet light exposure.

  7. Low-cost formation of bulk and localized polymer-derived carbon nanodomains from polydimethylsiloxane.

    PubMed

    Alcántara, Juan Carlos Castro; Cerda Zorrilla, Mariana; Cabriales, Lucia; Rossano, Luis Manuel León; Hautefeuille, Mathieu

    2015-01-01

    We present two simple alternative methods to form polymer-derived carbon nanodomains in a controlled fashion and at low cost, using custom-made chemical vapour deposition and selective laser ablation with a commercial CD-DVD platform. Both processes presented shiny and dark residual materials after the polymer combustion and according to micro-Raman spectroscopy of the domains, graphitic nanocrystals and carbon nanotubes have successfully been produced by the combustion of polydimethylsiloxane layers. The fabrication processes and characterization of the byproduct materials are reported. We demonstrate that CVD led to bulk production of graphitic nanocrystals and single-walled carbon nanotubes while direct laser ablation may be employed for the formation of localized fluorescent nanodots. In the latter case, graphitic nanodomains and multi-wall carbon nanotubes are left inside microchannels and preliminary results seem to indicate that laser ablation could offer a tuning control of the nature and optical properties of the nanodomains that are left inside micropatterns with on-demand geometries. These low-cost methods look particularly promising for the formation of carbon nanoresidues with controlled properties and in applications where high integration is desired. PMID:25977844

  8. Diode radial pumped composite microchip Yb:YAG laser: output performances and thermal effects

    NASA Astrophysics Data System (ADS)

    Dascalu, Traian; Pavel, Nicolaie A.; Taira, Takunori

    2004-10-01

    A diode radial pumped microchip Yb:YAG laser that consists of a Yb-doped core surrounded by undoped YAG of slab shape is presented. Quasi-continuous wave pumping of an 800-μm thick 10-at.% Yb doped core of 2 x 2 mm2 square shape with pulses of 5-Hz repetition rate and 2.5% duty cycle delivers 66-W output peak power at 220-W input pump power with 49% slope efficiency. 112-W peak power with 63% slope efficiency and 38% optical-to-optical efficiency, were obtained from a of 1.2 x 1.2 mm2 square 15-at.% Yb:YAG core of 800-μm thickness. Continuous-wave operation with up to 90 W were obtained from a 400-μm thick Yb:YAG/YAG structure with a 10-at.% Yb:YAG square core of 2x2-mm2 area; the slope efficiency and optical-to-optical efficiency with respect to the pump power were 40% and 28%, respectively. Measurements of the optical phase distortions induced by pumping gives focus shift bellow 0.05 m and shows the absence of astigmatic effects, indicating the axial heat flow in this pumping configuration.

  9. Microchip Screening Platform for Single Cell Assessment of NK Cell Cytotoxicity

    PubMed Central

    Guldevall, Karolin; Brandt, Ludwig; Forslund, Elin; Olofsson, Karl; Frisk, Thomas W.; Olofsson, Per E.; Gustafsson, Karin; Manneberg, Otto; Vanherberghen, Bruno; Brismar, Hjalmar; Kärre, Klas; Uhlin, Michael; Önfelt, Björn

    2016-01-01

    Here, we report a screening platform for assessment of the cytotoxic potential of individual natural killer (NK) cells within larger populations. Human primary NK cells were distributed across a silicon–glass microchip containing 32,400 individual microwells loaded with target cells. Through fluorescence screening and automated image analysis, the numbers of NK and live or dead target cells in each well could be assessed at different time points after initial mixing. Cytotoxicity was also studied by time-lapse live-cell imaging in microwells quantifying the killing potential of individual NK cells. Although most resting NK cells (≈75%) were non-cytotoxic against the leukemia cell line K562, some NK cells were able to kill several (≥3) target cells within the 12-h long experiment. In addition, the screening approach was adapted to increase the chance to find and evaluate serial killing NK cells. Even if the cytotoxic potential varied between donors, it was evident that a small fraction of highly cytotoxic NK cells were responsible for a substantial portion of the killing. We demonstrate multiple assays where our platform can be used to enumerate and characterize cytotoxic cells, such as NK or T cells. This approach could find use in clinical applications, e.g., in the selection of donors for stem cell transplantation or generation of highly specific and cytotoxic cells for adoptive immunotherapy. PMID:27092139

  10. Recent advances in the analysis of therapeutic proteins by capillary and microchip electrophoresis

    PubMed Central

    Creamer, Jessica S.; Oborny, Nathan J.; Lunte, Susan M.

    2014-01-01

    The development of therapeutic proteins and peptides is an expensive and time-intensive process. Biologics, which have become a multi-billion dollar industry, are chemically complex products that require constant observation during each stage of development and production. Post-translational modifications along with chemical and physical degradation from oxidation, deamidation, and aggregation, lead to high levels of heterogeneity that affect drug quality and efficacy. The various separation modes of capillary electrophoresis (CE) are commonly utilized to perform quality control and assess protein heterogeneity. This review attempts to highlight the most recent developments and applications of CE separation techniques for the characterization of protein and peptide therapeutics by focusing on papers accepted for publication in the in the two-year period between January 2012 and December 2013. The separation principles and technological advances of CE, capillary gel electrophoresis, capillary isoelectric focusing, capillary electrochromatography and CE-mass spectrometry are discussed, along with exciting new applications of these techniques to relevant pharmaceutical issues. Also included is a small selection of papers on microchip electrophoresis to show the direction this field is moving with regards to the development of inexpensive and portable analysis systems for on-site, high-throughput analysis. PMID:25126117

  11. Electroporation on microchips: the harmful effects of pH changes and scaling down

    PubMed Central

    Li, Yang; Wu, Mengxi; Zhao, Deyao; Wei, Zewen; Zhong, Wenfeng; Wang, Xiaoxia; Liang, Zicai; Li, Zhihong

    2015-01-01

    Electroporation has been widely used in delivering foreign biomolecules into cells, but there is still much room for improvement, such as cell viability and integrity. In this manuscript, we investigate the distribution and the toxicity of pH changes during electroporation, which significantly decreases cell viability. A localized pH gradient forms between anode and cathode leading to a localized distribution of cell death near the electrodes, especially cathodes. The toxicity of hydroxyl ions is severe and acute due to their effect in the decomposition of phospholipid bilayer membrane. On the other hand, the electric field used for electroporation aggravates the toxicity of hydroxyl because the electropermeabilization of cell membrane makes bilayer structure more loosen and vulnerable. We also investigate the side effects during scaling down the size of electrodes in electroporation microchips. Higher percentage of cells is damaged when the size of electrodes is smaller. At last, we propose an effective strategy to constrain the change of pH by modifying the composition of electroporation buffer. The modified buffer decreases the changes of pH, thus enables high cell viability even when the electric pulse duration exceeds several milliseconds. This ability has potential advantage in some applications that require long-time electric pulse stimulation. PMID:26658168

  12. Constitutive computational modelling foundation of piezoelectronic microstructures and application to high-frequency microchip DSAW resonators

    NASA Astrophysics Data System (ADS)

    Wu, Zhang; Jinchun, Tang

    2002-04-01

    This paper establishes a piezoelectric constitutive computational approach based on generalized eigenvalue and multivariable finite element solutions with potential applications to accurate and effective analysis of layered piezoelectric microstructures of arbitrary geometries and different anisotropic materials, to ease the limitation of current computer capacity in analyzing large-scale high-frequency disturbed surface acoustic waves (DSAW) by mounted electrodes in piezoelectric devices such as microchip SAW resonators. A new incompatible generalized hybrid/mixed element GQM5 is also proposed for improving predictions of the piezoelectric surface mount thermal stresses that are shear-dominated. The (generalized) plane strain constitutive model is numerically verified for piezoelectric finite element computation. With the help of computational piezoelectricity (electro-mechanics) for general layered structures with metal electrodes and anisotropic piezoelectric substrates, some new interesting, reliable and fundamental constitutive finite element results are obtained for high-frequency piezoelectric and mechanical SAW propagations and can be used for further applications. The ST-cut FEA results agree quite well with available exact and lab solutions for free surface case.

  13. Experimental and numerical analysis of high-resolution injection technique for capillary electrophoresis microchip.

    PubMed

    Chang, Chin-Lung; Leong, Jik-Chang; Hong, Ting-Fu; Wang, Yao-Nan; Fu, Lung-Ming

    2011-01-01

    This study presents an experimental and numerical investigation on the use of high-resolution injection techniques to deliver sample plugs within a capillary electrophoresis (CE) microchip. The CE microfluidic device was integrated into a U-shaped injection system and an expansion chamber located at the inlet of the separation channel, which can miniize the sample leakage effect and deliver a high-quality sample plug into the separation channel so that the detection performance of the device is enhanced. The proposed 45° U-shaped injection system was investigated using a sample of Rhodamine B dye. Meanwhile, the analysis of the current CE microfluidic chip was studied by considering the separation of Hae III digested ϕx-174 DNA samples. The experimental and numerical results indicate that the included 45° U-shaped injector completely eliminates the sample leakage and an expansion separation channel with an expansion ratio of 2.5 delivers a sample plug with a perfect detection shape and highest concentration intensity, hence enabling an optimal injection and separation performance. PMID:21747696

  14. Sacrificial adhesive bonding: a powerful method for fabrication of glass microchips

    PubMed Central

    Lima, Renato S.; Leão, Paulo A. G. C.; Piazzetta, Maria H. O.; Monteiro, Alessandra M.; Shiroma, Leandro Y.; Gobbi, Angelo L.; Carrilho, Emanuel

    2015-01-01

    A new protocol for fabrication of glass microchips is addressed in this research paper. Initially, the method involves the use of an uncured SU-8 intermediate to seal two glass slides irreversibly as in conventional adhesive bonding-based approaches. Subsequently, an additional step removes the adhesive layer from the channels. This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests. Named sacrificial adhesive layer (SAB), the protocol meets the requirements of an ideal microfabrication technique such as throughput, relatively low cost, feasibility for ultra large-scale integration (ULSI), and high adhesion strength, supporting pressures on the order of 5 MPa. Furthermore, SAB eliminates the use of high temperature, pressure, or potential, enabling the deposition of thin films for electrical or electrochemical experiments. Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature. Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives. PMID:26293346

  15. Performance of HPLC/MS microchips in isocratic and gradient elution modes.

    PubMed

    Ehlert, Steffen; Trojer, Lukas; Vollmer, Martin; van de Goor, Tom; Tallarek, Ulrich

    2010-03-01

    We analyzed the chromatographic performance of particle-packed, all-polyimide high-performance liquid chromatography/mass spectrometry (HPLC/MS) microchips in terms of their hydraulic permeabilities and separation efficiency under isocratic and gradient elution conditions. The separation channels of the chips (with ca 50 microm x 75 microm trapezoidal cross-section and a length of 43 mm) were slurry packed with either 3.5 or 5 microm spherical porous C18-silica particles. A custom-built holder enveloped the chip during packing to prevent channel deformation and delamination from high pressures. It is shown that the packing conditions significantly impact the packing density of the HPLC/MS chips, which determines their performance in both, isocratic and gradient elution modes. Even with steep solvent gradients, peak shape and chromatographic resolution for the densely packed HPLC/MS chips are much improved. Our data show that the analytical power of the HPLC/MS chip is limited by the quality of the chromatographic separation. PMID:20209581

  16. Dual contactless conductivity and amperometric detection on hybrid PDMS/glass electrophoresis microchips.

    PubMed

    Vázquez, Mercedes; Frankenfeld, Celeste; Coltro, Wendell K Tomazelli; Carrilho, Emanuel; Diamond, Dermot; Lunte, Susan M

    2010-01-01

    A new approach for the integration of dual contactless conductivity and amperometric detection with an electrophoresis microchip system is presented. The PDMS layer with the embedded channels was reversibly sealed to a thin glass substrate (400 microm), on top of which a palladium electrode had been previously fabricated enabling end-channel amperometric detection. The thin glass substrate served also as a physical wall between the separation channel and the sensing copper electrodes for contactless conductivity detection. The latter were not integrated in the microfluidic device, but fabricated on an independent plastic substrate allowing a simpler and more cost-effective fabrication of the chip. PDMS/glass chips with merely contactless conductivity detection were first characterized in terms of sensitivity, efficiency and reproducibility. The separation efficiency of this system was found to be similar or slightly superior to other systems reported in the literature. The simultaneous determination of ionic and electroactive species was illustrated by the separation of peroxynitrite degradation products, i.e. NO(3)(-) (non-electroactive) and NO(2)(-) (electroactive), using hybrid PDMS/glass chips with dual contactless conductivity and amperometric detection. While both ions were detected by contactless conductivity detection with good efficiency, NO(2)(-) was also simultaneously detected amperometrically with a significant enhancement in sensitivity compared to contactless conductivity detection. PMID:20024187

  17. Amperometric Detection in Microchip Electrophoresis Devices: Effect of Electrode Material and Alignment on Analytical Performance

    PubMed Central

    Fischer, David J.; Hulvey, Matthew K.; Regel, Anne R.; Lunte, Susan M.

    2012-01-01

    The fabrication and evaluation of different electrode materials and electrode alignments for microchip electrophoresis with electrochemical (EC) detection is described. The influences of electrode material, both metal and carbon-based, on sensitivity and limits of detection (LOD) were examined. In addition, the effects of working electrode alignment on analytical performance (in terms of peak shape, resolution, sensitivity, and LOD) were directly compared. Using dopamine (DA), norepinephrine (NE), and catechol (CAT) as test analytes, it was found that pyrolyzed photoresist electrodes with end-channel alignment yielded the lowest limit of detection (35 nM for DA). In addition to being easier to implement, end-channel alignment also offered better analytical performance than off-channel alignment for the detection of all three analytes. In-channel electrode alignment resulted in a 3.6-fold reduction in peak skew and reduced peak tailing by a factor of 2.1 for catechol in comparison to end-channel alignment. PMID:19802847

  18. Sacrificial adhesive bonding: a powerful method for fabrication of glass microchips

    NASA Astrophysics Data System (ADS)

    Lima, Renato S.; Leão, Paulo A. G. C.; Piazzetta, Maria H. O.; Monteiro, Alessandra M.; Shiroma, Leandro Y.; Gobbi, Angelo L.; Carrilho, Emanuel

    2015-08-01

    A new protocol for fabrication of glass microchips is addressed in this research paper. Initially, the method involves the use of an uncured SU-8 intermediate to seal two glass slides irreversibly as in conventional adhesive bonding-based approaches. Subsequently, an additional step removes the adhesive layer from the channels. This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests. Named sacrificial adhesive layer (SAB), the protocol meets the requirements of an ideal microfabrication technique such as throughput, relatively low cost, feasibility for ultra large-scale integration (ULSI), and high adhesion strength, supporting pressures on the order of 5 MPa. Furthermore, SAB eliminates the use of high temperature, pressure, or potential, enabling the deposition of thin films for electrical or electrochemical experiments. Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature. Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives.

  19. Analysis of mutations in oral poliovirus vaccine by hybridization with generic oligonucleotide microchips.

    SciTech Connect

    Proudnikov, D.; Kirillov, E.; Chumakov, K.; Donion, J.; Rezapkin, G.; Mirzabekov, A.; Biochip Technology Center; Engelhardt Inst. of Molecular Biology; Center for Biologics Evaluation and Research

    2000-01-01

    This paper describes use of a new technology of hybridization with a micro-array of immobilized oligonucleotides for detection and quantification of neurovirulent mutants in Oral Poliovirus Vaccine (OPV). We used a micro-array consisting of three-dimensional gel-elements containing all possible hexamers (total of 4096 probes). Hybridization of fluorescently labelled viral cDNA samples with such microchips resulted in a pattern of spots that was registered and quantified by a computer-linked CCD camera, so that the sequence of the original cDNA could be deduced. The method could reliably identify single point mutations, since each of them affected fluorescence intensity of 12 micro-array elements. Micro-array hybridization of DNA mixtures with varying contents of point mutants demonstrated that the method can detect as little as 10% of revertants in a population of vaccine virus. This new technology should be useful for quality control of live viral vaccines, as well as for other applications requiring identification and quantification of point mutations.

  20. Application of an external contactless conductivity detector for the analysis of beverages by microchip capillary electrophoresis.

    PubMed

    Kubán, Pavel; Hauser, Peter C

    2005-08-01

    Quantitative total ionic analysis of alcoholic and nonalcoholic beverages was performed by microchip capillary electrophoresis with external contactless conductivity detection. An electrolyte solution consisting of 10.5 mM histidine, 50 mM acetic acid, and 2 mM 18-crown-6 at pH 4.1 was used for the determination of NH(4) (+), K(+), Ca(2+), Na(+), and Mg(2+). Fast analysis of Cl(-), NO(3) (-), and SO(4) (2-) was achieved in 20 mM 2-(N-morpholino)ethanesulfonic acid /histidine electrolyte solution at pH 6.0 and the simultaneous separation of up to 12 inorganic and organic anions was performed in a solution containing 10 mM His and 7 mM glutamic acid at pH 5.75. Limits of detection ranged from 90 to 250 mug/L for inorganic cations and anions, and from 200 to 2000 mug/L for organic anions and phosphate. Calibration curves showed linear dependencies over one to two orders of magnitude when the stacking effect was minimized by injecting standard solutions prepared in background electrolyte solutions. Total analysis times of 35 and 90 s were achieved for the determination of 5 inorganic cations and for the simultaneous determination of 12 inorganic and organic anions, respectively, which represents a considerable reduction of analysis time compared to conventional separation methods used in food analysis. PMID:16047312

  1. [IDENTIFICATION OF A NEW DIAGNOSTIC MARKERS OF PROSTATIC CANCER, USING NOTI-MICROCHIPS].

    PubMed

    Vozianov, S O; Kashuba, V I; Grygorenko, V M; Gordiyuk, V V; Danylets, R O; Bondarenko, Yu M; Vikarchuk, M V

    2016-04-01

    The biopsy material specimens were investigated in 33 patients, examined for the prostatic cancer suspicion. In accordance to the morphological investigation data, in 15 patients a benign prostatic hyperplasia was verified, and in 18--pancreatic adenocarcinoma. NotI-Microchips of 180 clones of the third chromosome were used for determination of epigenetic changes. In 50 genes of the third chromosome a high rate of the methylation state changes (from 33 to 82%) was noted. Some changed genes take part in cancerogenesis (HMGB1L5, LRRC58, GPR149, DZIP1L, C3orf77, NUDT16) and in the prostatic gland cancer occurrence (BCL6, ITGA9, FBLN2, SOX2, LRRC3B etc.). Dependence of the genes methylation state from the clinic-morphological indices in patients with the prostatic gland cancer, including, the prostate-specific antigen level, the tumor differentiation degree in accordance to Gleason, was not established. Panel, consisting of 16 new potential markers for early and differentiated diagnosis of prostatic gland cancer, was identified: BHLHE40, FOXP1, LOC285205, ITGA9, CTDSPL, FGF12, LOC440944/SETD5, VHL, CLCN2, OSBPL10/ZNF860, LMCD1, FAM19A4, CAND2, MAP4, KY and LRRC58. PMID:27434957

  2. Development of monolith Nd:YAG /Cr+4:YAG passively Q-switched microchip laser

    NASA Astrophysics Data System (ADS)

    Izhnin, Ihor; Vakiv, Mykola; Izhnin, Aleksandr; Syvorotka, Igor; Ubizskii, Sergii; Syvorotka, Ihor, Jr.

    2005-09-01

    The main features of passively Q-switched microchip lasers development are considered. The active medium of laser is an epitaxial structure combining an epitaxial layer of saturable absorber Cr4+:Y3Al5O12 (Cr:YAG) grown on substrate of generating crystal Nd:YAG by liquid phase epitaxy. The modulator layer has an initial optical absorption of 36 cm-1 at wavelength of lasing (1064 nm). The epitaxial layer grown on unworking side was mechanically removed and this substrate side was optically polished. The other one was processed precisely to needed thickness. The cavity's mirrors were deposited by electron beam technique directly on each side of the structure to form a rugged, monolithic resonator. Diode laser Model ATC-C4000 with lasing wavelength 808 nm provided the CW end pumping. The output pulses parameters were investigated by means of test bench consisting of photoelectric transducer FEK-15 and Digital Phosphor Oscilloscope TDS 5052B. The obtained laser parameter are as follows: pulse width (FWHM) about 1.3 ns, repetition rate 5.5 kHz, average output power about 10 mW, pulse energy 1.0 μJ, pick power 1.2 kW. The possible solutions for laser parameter improving and optimization are discussed.

  3. Stand-Sit Microchip for High-Throughput, Multiplexed Analysis of Single Cancer Cells.

    PubMed

    Ramirez, Lisa; Herschkowitz, Jason I; Wang, Jun

    2016-01-01

    Cellular heterogeneity in function and response to therapeutics has been a major challenge in cancer treatment. The complex nature of tumor systems calls for the development of advanced multiplexed single-cell tools that can address the heterogeneity issue. However, to date such tools are only available in a laboratory setting and don't have the portability to meet the needs in point-of-care cancer diagnostics. Towards that application, we have developed a portable single-cell system that is comprised of a microchip and an adjustable clamp, so on-chip operation only needs pipetting and adjusting of clamping force. Up to 10 proteins can be quantitated from each cell with hundreds of single-cell assays performed in parallel from one chip operation. We validated the technology and analyzed the oncogenic signatures of cancer stem cells by quantitating both aldehyde dehydrogenase (ALDH) activities and 5 signaling proteins in single MDA-MB-231 breast cancer cells. The technology has also been used to investigate the PI3K pathway activities of brain cancer cells expressing mutant epidermal growth factor receptor (EGFR) after drug intervention targeting EGFR signaling. Our portable single-cell system will potentially have broad application in the preclinical and clinical settings for cancer diagnosis in the future. PMID:27581736

  4. Stand-Sit Microchip for High-Throughput, Multiplexed Analysis of Single Cancer Cells

    PubMed Central

    Ramirez, Lisa; Herschkowitz, Jason I.; Wang, Jun

    2016-01-01

    Cellular heterogeneity in function and response to therapeutics has been a major challenge in cancer treatment. The complex nature of tumor systems calls for the development of advanced multiplexed single-cell tools that can address the heterogeneity issue. However, to date such tools are only available in a laboratory setting and don’t have the portability to meet the needs in point-of-care cancer diagnostics. Towards that application, we have developed a portable single-cell system that is comprised of a microchip and an adjustable clamp, so on-chip operation only needs pipetting and adjusting of clamping force. Up to 10 proteins can be quantitated from each cell with hundreds of single-cell assays performed in parallel from one chip operation. We validated the technology and analyzed the oncogenic signatures of cancer stem cells by quantitating both aldehyde dehydrogenase (ALDH) activities and 5 signaling proteins in single MDA-MB-231 breast cancer cells. The technology has also been used to investigate the PI3K pathway activities of brain cancer cells expressing mutant epidermal growth factor receptor (EGFR) after drug intervention targeting EGFR signaling. Our portable single-cell system will potentially have broad application in the preclinical and clinical settings for cancer diagnosis in the future. PMID:27581736

  5. Contactless conductivity detection of sodium monofluoroacetate in fruit juices on a CE microchip.

    PubMed

    Lu, Qin; Wu, Peter; Collins, Greg E

    2007-10-01

    Rapid and quantitative determination of sodium monofluoroacetate in diluted fruit juices (dilution 1:9 v/v in deionized water) and tap water was performed by microchip CE, using contactless conductivity detection. A separation buffer consisting of 20 mM citric acid and histidine at pH 3.5 enabled the detection of the monofluoroacetate (MFA) anion in diluted apple juice, cranberry juice, and orange juice without lengthy sample pretreatments. The analyte was very well separated from interfering anionic species present in juices and tap water. LODs in diluted juices and tap water were determined to be 125, 167, 138, and 173 microg/L for tap water, apple juice, cranberry juice, and orange juice, respectively, based upon an S/N of 3:1. Taking into account the dilution factor, the LODs for juice samples range from 1 to 2 mg/L, which is adequate for monitoring the toxicity of MFA in these juice beverages and tap water. The calibration curves for MFA in diluted fruit juices were linear over the range of 500 microg/L to 80 mg/L. 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. PMID:17768724

  6. A microchip laser source with stable intensity and frequency used for self-mixing interferometry.

    PubMed

    Zhang, Shaohui; Zhang, Shulian; Tan, Yidong; Sun, Liqun

    2016-05-01

    We present a stable 40 × 40 × 30 mm(3) Laser-diode (LD)-pumped-microchip laser (ML) laser source used for self-mixing interferometry which can measure non-cooperative targets. We simplify the coupling process of pump light in order to make its polarization and intensity robust against environmental disturbance. Thermal frequency stabilization technology is used to stabilize the laser frequency of both LD and ML. Frequency stability of about 1 × 10(-7) and short-term intensity fluctuation of 0.1% are achieved. The theoretical long-term displacement accuracy limited by frequency and intensity fluctuation is about 10 nm when the measuring range is 0.1 m. The line-width of this laser is about 25 kHz corresponding to 12 km coherent length and 6 km measurement range for self-mixing interference. The laser source has been equipped to a self-mixing interferometer, and it works very well. PMID:27250399

  7. Improving sensitivity for microchip electrophoresis interfaced with inductively coupled plasma mass spectrometry using parallel multichannel separation.

    PubMed

    Cheng, Heyong; Liu, Jinhua; Xu, Zigang; Wang, Yuanchao; Ye, Meiying

    2016-08-26

    We reported sensitivity enhancement using multichannel parallel separation for microchip electrophoresis hyphenated with inductively coupled plasma mass spectrometry (MCE-ICP-MS) in this study. By using 2-20 array lanes for parallel separation, the sensitivity of the MCE-ICP-MS system was proportionally improved by 2-20 folds. No significantly adverse effect of parallel separation on column efficiency and resolution was observed. Rapid separation of Hg(2+) and methylmercuric (MeHg) ion within 36s under an electric field of 800Vcm(-1) was achieved in the 2-cm twenty-channels with a background electrolyte of 5mmolL(-1) borate buffer (pH 9.2). Detection limits of Hg(2+) and MeHg by the proposed system were decreased to 6.8-7.1ngL(-1). Good agreement between determined values and certified values of a certified reference fish was obtained with recoveries ranged between 94-98%. All results prove its advantages including high sensitivity, high efficiency and low operation cost, which are beneficial to routine analysis of metal speciation in environmental, biological and food fields. PMID:27488720

  8. Microchip capillary electrophoresis instrumentation for in situ analysis in the search for extraterrestrial life.

    PubMed

    Mora, Maria F; Stockton, Amanda M; Willis, Peter A

    2012-09-01

    The search for signs of life on extraterrestrial planetary bodies is among NASA's top priorities in Solar System exploration. The associated pursuit of organics and biomolecules as evidence of past or present life demands in situ investigations of planetary bodies for which sample return missions are neither practical nor affordable. These in situ studies require instrumentation capable of sensitive chemical analyses of complex mixtures including a broad range of organic molecules. Instrumentation must also be capable of autonomous operation aboard a robotically controlled vehicle that collects data and transmits it back to Earth. Microchip capillary electrophoresis (μCE) coupled to laser-induced fluorescence (LIF) detection provides this required sensitivity and targets a wide range of relevant organics while offering low mass, volume, and power requirements. Thus, this technology would be ideally suited for in situ studies of astrobiology targets, such as Mars, Europa, Enceladus, and Titan. In this review, we introduce the characteristics of these planetary bodies that make them compelling destinations for extraterrestrial astrobiological studies, and the principal groups of organics of interest associated with each. And although the technology we describe here was first developed specifically for proposed studies of Mars, by summarizing its evolution over the past decade, we demonstrate how μCE-LIF instrumentation has become an ideal candidate for missions of exploration to all of these nearby worlds in our Solar System. PMID:22965706

  9. Recent developments in capillary and microchip electroseparations of peptides (2013-middle 2015).

    PubMed

    Kašička, Václav

    2016-01-01

    The review brings a comprehensive survey of recent developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) to analysis, micropreparation, purification, and physicochemical and biochemical characterization of peptides in the years 2013, 2014, and ca. up to the middle of 2015. Advances in the investigation of electromigration properties of peptides, in the methodology of their analysis, including sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, as well as in detection of peptides, are described. New developments in particular CE and CEC modes are presented and several types of their applications to peptide analysis are reported: conventional qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence, and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC techniques to provide important physicochemical characteristics of peptides are demonstrated. PMID:26332110

  10. Engineering the bioelectrochemical interface using functional nanomaterials and microchip technique toward sensitive and portable electrochemical biosensors.

    PubMed

    Jia, Xiaofang; Dong, Shaojun; Wang, Erkang

    2016-02-15

    Electrochemical biosensors have played active roles at the forefront of bioanalysis because they have the potential to achieve sensitive, specific and low-cost detection of biomolecules and many others. Engineering the electrochemical sensing interface with functional nanomaterials leads to novel electrochemical biosensors with improved performances in terms of sensitivity, selectivity, stability and simplicity. Functional nanomaterials possess good conductivity, catalytic activity, biocompatibility and high surface area. Coupled with bio-recognition elements, these features can amplify signal transduction and biorecognition events, resulting in highly sensitive biosensing. Additionally, microfluidic electrochemical biosensors have attracted considerable attention on account of their miniature, portable and low-cost systems as well as high fabrication throughput and ease of scaleup. For example, electrochemical enzymetic biosensors and aptamer biosensors (aptasensors) based on the integrated microchip can be used for portable point-of-care diagnostics and environmental monitoring. This review is a summary of our recent progress in the field of electrochemical biosensors, including aptasensors, cytosensors, enzymatic biosensors and self-powered biosensors based on biofuel cells. We presented the advantages that functional nanomaterials and microfluidic chip technology bring to the electrochemical biosensors, together with future prospects and possible challenges. PMID:26001888

  11. Optimization of the separation of NDA-derivatized methylarginines by capillary and microchip electrophoresis.

    PubMed

    Linz, Thomas H; Snyder, Christa M; Lunte, Susan M

    2012-02-01

    The methylated arginines (MAs) monomethylarginine (MMA), asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) have been shown to be independent predictors of cardiovascular disease. This article describes progress regarding the development of an analytical method capable of rapidly analyzing MAs using capillary electrophoresis (CE) and microchip electrophoresis (MCE) with laser-induced fluorescence (LIF) detection. Several parameters including buffer composition and separation voltage were optimized to achieve an ideal separation. The analytes of interest were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) to produce fluorescent 1-cyanobenz[f]isoindole (CBI) derivatives and then subjected to CE analysis. Baseline resolution of SDMA, ADMA, MMA, and arginine was achieved in less than 8 min. The limits of detection for SDMA, ADMA, MMA, and arginine were determined to be 15, 20, 25, and 5 nM, respectively, which are well below the expected plasma concentrations. The CE separation method was then transferred to a glass MCE device with LIF detection. MAs were baseline resolved in 3 min on-chip using a 14 cm separation channel with detection limits of approximately 10 nM for each species. To the best of the authors' knowledge, this is the first report of the separation of MAs by MCE. PMID:22357605

  12. Optimization of an oligonucleotide microchip for microbial identification studies: a non-equilibrium dissociation approach

    NASA Technical Reports Server (NTRS)

    Liu, W. T.; Mirzabekov, A. D.; Stahl, D. A.

    2001-01-01

    The utility of a high-density oligonucleotide microarray (microchip) for identifying strains of five closely related bacilli (Bacillus anthracis, Bacillus cereus, Bacillus mycoides, Bacillus medusa and Bacillus subtilis) was demonstrated using an approach that compares the non-equilibrium dissociation rates ('melting curves') of all probe-target duplexes simultaneously. For this study, a hierarchical set of 30 oligonucleotide probes targeting the 16S ribosomal RNA of these bacilli at multiple levels of specificity (approximate taxonomic ranks of domain, kingdom, order, genus and species) was designed and immobilized in a high-density matrix of gel pads on a glass slide. Reproducible melting curves for probes with different levels of specificity were obtained using an optimized salt concentration. Clear discrimination between perfect match (PM) and mismatch (MM) duplexes was achieved. By normalizing the signals to an internal standard (a universal probe), a more than twofold discrimination (> 2.4x) was achieved between PM and 1-MM duplexes at the dissociation temperature at which 50% of the probe-target duplexes remained intact. This provided excellent differentiation among representatives of different Bacillus species, both individually and in mixtures of two or three. The overall pattern of hybridization derived from this hierarchical probe set also provided a clear 'chip fingerprint' for each of these closely related Bacillus species.

  13. Morbus Coats

    PubMed Central

    Förl, B.; Schmack, I.; Grossniklaus, H.E.; Rohrschneider, K.

    2010-01-01

    Der fortgeschrittene Morbus Coats stellt im Kleinkindalter eine der schwierigsten Differenzialdiagnosen zum Retinoblastom dar. Wir beschreiben die klinischen und histologischen Befunde zweier Jungen im Alter von 9 und 21 Monaten mit einseitiger Leukokorie. Trotz umfassender Diagnostik mittels Narkoseuntersuchung, MRT und Ultraschall konnte ein Retinoblastom nicht sicher ausgeschlossen werden, und es erfolgte eine Enukleation. Histologisch wurde die Diagnose eines Morbus Coats gesichert. Da eine differenzialdiagnostische Abgrenzung zwischen Morbus Coats und Retinoblastom schwierig sein kann, halten wir in zweifelhaften Fällen auch angesichts der eingeschränkten Visusprognose und potenzieller Sekundärkomplikationen beim fortgeschrittenen Morbus Coats eine Enukleation für indiziert. PMID:18299842

  14. Mitigated reactive oxygen species generation leads to an improvement of cell proliferation on poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] functionalized polydimethylsiloxane surfaces.

    PubMed

    Yu, Ling; Shi, ZhuanZhuan; Gao, LiXia; Li, ChangMing

    2015-09-01

    In vitro cell-based analysis is strongly affected by material's surface chemical properties. The cell spreading, migration, and proliferation on a substrate surface are initiated and controlled by successful adhesion, particularly for anchor-dependent cells. Unfortunately, polydimethylsiloxane (PDMS), one of the most used polymeric materials for construction of microfluidic and miniaturized biomedical analytic devices, is not a cell-friendly surface because of its inherent hydrophobic property. Herein, a poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] (poly(GMA-co-pEGMA)) polymer brush was synthesized on a PDMS surface through a surface-initiated atom-transfer radical polymerization method. Contact angle and Fourier transform infrared characterization show that the poly (GMA-co-pEGMA) polymer brush functionalization can increase wettability of PDMS and introduce epoxy, hydroxyl, and ether groups into PDMS surface. In vitro cell growth assay demonstrates that cell adhesion and proliferation on poly(GMA-co-pEGMA) polymer brush-functionalized PDMS (poly(GMA-co-pEGMA)@PDMS) are better than on pristine PDMS. Additionally, immobilization of collagen type I (CI) and fibronectin (FN) on poly(GMA-co-pEGMA)@PDMS is better than direct coating of CI and FN on pristine PDMS to promote cell adhesion. Furthermore, increased intracellular reactive oxygen species and cell mitochondrial membrane depolarization, two indicators of cell oxidative stress, are observed from cells growing on pristine PDMS, but not from those on poly(GMA-co-pEGMA)@PDMS. Collectively, we demonstrate that poly(GMA-co-pEGMA) functionalization can enhance cell adhesion and proliferation on PDMS, and thus can be potentially used for microfluidic cell assay devices for cellular physiology study or drug screening. PMID:25711883

  15. Integration of a Graphite/PMMA CompositeElectrode into a Poly(methyl methacrylate) (PMMA) Substrate for Electrochemical Detection in Microchips

    PubMed Central

    Regel, Anne; Lunte, Susan

    2013-01-01

    Traditional fabrication methods for polymer microchips, the bonding of two substrates together to form the microchip, can make the integration of carbon electrodes difficult. We have developed a simple and inexpensive method to integrate graphite/PMMA composite electrodes (GPCEs) into a PMMA substrate. These substrates can be bonded to other PMMA layers using a solvent-assisted thermal bonding method. The optimal composition of the GPCEs for electrochemical detection was determined using cyclic voltammetry with dopamine as a test analyte. Using the optimized GPCEs in an all-PMMA flow cell with flow injection analysis, it was possible to detect 50 nM dopamine under the best conditions. These electrodes were also evaluated for the detection of dopamine and catechol following separation by microchip electrophoresis (ME). PMID:23670816

  16. A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for controllable high-order Hermite–Gaussian modes

    NASA Astrophysics Data System (ADS)

    Dong, Jun; He, Yu; Bai, Sheng-Chuang; Ueda, Ken-ichi; Kaminskii, Alexander A.

    2016-09-01

    A nanosecond, high peak power, passively Q-switched laser for controllable Hermite–Gaussian (HG) modes has been achieved by manipulating the saturated inversion population inside the gain medium. The stable HG modes are generated in a Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser by applying a tilted pump beam. The asymmetrical saturated inversion population distribution inside the Nd:YVO4 crystal for desirable HG modes is manipulated by choosing the proper pump beam diameter and varying pump power. A HG9,8 mode passively Q-switched Nd:YVO4 microchip laser with average output power of 265 mW has been obtained. Laser pulses with a pulse width of 7.3 ns and peak power of over 1.7 kW working at 21 kHz have been generated in the passively Q-switched Nd:YVO4 microchip laser.

  17. Coatings Guide

    EPA Science Inventory

    The Coatings Guide is a free online information resource that focuses on alternative, low-emission coatings for metal, plastic, and architectural substrates. Developed cooperatively by the U.S. EPA's Office of Research and Development and Research Triangle Institute (RTI) Interna...

  18. Application of capacitively coupled contactless conductivity as an external detector for zone electrophoresis in poly(dimethylsiloxane) chips.

    PubMed

    Koczka, Péter I; Bodoki, Ede; Gáspár, Attila

    2016-02-01

    In this work, lab-made PDMS microfluidic chips were matched to a capacitively coupled contactless conductivity detector (C(4) D) having external in-plane electrodes (eDAQ, Australia). The advantages of this type of C(4) D are the choice to reversibly place or remove the microchip onto/from the detector and to freely variate the position of the detection (separation length) on the microchip. The thickness of the bottom layer of the PDMS chip was optimized to achieve sensitive detection during the electrophoretic separation. PDMS chips with 100 μm bottom layer used with the C(4) D platform were tested by CZE of a mixture of seven anions and different types of real samples. Using split-flow pressure sample injection and effective length of 6.5 cm, the numbers of theoretical plates were in the range of 4000-6000 (63,000-93,000/m) and the LODs amounted to 3.66-14.7 μmol/L (0.13-2.26 μg/mL) for the studied anions. PMID:26531885

  19. Detection of immunoglobulins in a laser induced fluorescence system utilizing polydimethysiloxane microchips with advanced surface and optical properties.

    PubMed

    Schrott, Walter; Nebyla, Marek; Přibyl, Michal; Snita, Dalimil

    2011-01-01

    We developed an automated laser induced fluorescence system utilizing microfluidic chips for detection and quantification of immunoglobulins. Microchips were fabricated from polydimethysiloxane (PDMS) using the so-called "prepolymerization technique." The microchip structure helped minimize the effects of PDMS autofluorescence and light scattering. Furthermore, a thin and uniform PDMS layer forming the top of the microchip enabled proper focusing and collection of the excitation beam and the emitted fluorescence, respectively. The developed system was tested for the detection of mouse immunoglobulins. The capturing antibodies were immobilized on internal microchannel walls in the form of a polyelectrolyte. We clearly show that this immobilization technique, if correctly realized, gives results with high reproducibility. After sample incubation and washing, secondary antibodies labeled by fluorescein isothiocyanate were introduced into microchannels to build a detectable complex. We show that mouse antibodies can be quantified in a wide concentration range, 0.01-100 μg ml(-1). The lower detection limit was below 0.001 μg ml(-1) (6.7 pM). The developed laser induced fluorescence (LIF) apparatus is relatively cheap and easy to construct. The total cost of the developed LIF detector is lower than a typical price of plate readers. If compared to classical ELISA (enzyme linked immunosorbent assay) plate systems, the detection of immunoglobulins or other proteins in the developed PDMS microfluidic device brings other important benefits such as reduced time demands (10 min incubation) and low reagent consumption (less than 1 μl). The cost of the developed PDMS chips is comparable with the price of commercial ELISA plates. The main troubleshooting related to the apparatus development is also discussed in order to help potential constructors. PMID:21359027

  20. Optimization of microchip-based electrophoresis for monoclonal antibody product quality analysis revealed needs for extra surfactants during denaturation.

    PubMed

    Cai, Hui; Song, Yuanli; Zhang, Jian; Shi, Ting; Fu, Ya; Li, Rong; Mussa, Nesredin; Li, Zheng Jian

    2016-02-20

    Microchip-based electrophoresis has gained increasing popularity in biopharmaceutical development and testing laboratories because of its automation and rapid analysis capabilities. One application of microchip-based electrophoresis is the assessment of size-based variants for product purity analysis. However, monoclonal antibodies analyzed by this technique sometimes exhibited different electrophoretic behaviors. In this study, when three IgG1 and five IgG4 were analyzed using microchip-based electrophoresis under reducing conditions, one of the IgG1s, denoted as mAb1, exhibited an atypical profile attributed to its specific heterogeneity resulting in separation of its heavy chain into two main species. During investigation of the atypical profile, several parameters that were critical to optimal resolution were evaluated, and the data pointed toward incomplete denaturation of mAb1 due to lack of sufficient surfactant in the vendor provided sample buffer (0.7% surfactant). Denaturation studies demonstrated that, although typical antibody profiles could be achieved at 0.7% surfactant for most antibodies analyzed, five out of eight antibodies were not fully denatured until the surfactant concentration reached 0.9% or higher, and mAb1 required a surfactant concentration of 1.3% for complete denaturation. Molecular modeling analysis revealed features in surface charge, hydrophobicity, and structure from mAb1 that led to its unique surfactant concentration-dependent electrophoretic behaviors observed. The optimized method was further evaluated for specificity, linearity, precision, and limit of quantitation for mAb1, and compared with that of conventional CE-SDS. PMID:26704629

  1. Microchip-based terminal restriction fragment length polymorphism for on-site analysis of bacterial communities in freshwater.

    PubMed

    Yamaguchi, Nobuyasu; Matsukawa, Syuhei; Shintome, Yoko; Ichijo, Tomoaki; Nasu, Masao

    2013-01-01

    Assessing microbiological quality assurance by monitoring bacteria in various sources of freshwater used for human consumption, recreation, and food preparation is important for a healthy life. Bacterial number and their community structure in freshwater should be determined as quickly as possible, and "real-time" and "on-site" microbiological methods are required. In this study, we examined the protocol for microchip-based terminal restriction fragment length polymorphism (T-RFLP) analysis, which uses microchip electrophoresis for rapid microbial community analysis. The availability of microchip-based T-RFLP was compared with conventional T-RFLP analysis, which uses a capillary electrophoresis system, with freshwater samples (spring water, river water, groundwater, and hydroponics solution). The detection limit of targeted bacteria by on-chip T-RFLP analysis was 1% (10(3) cells/mL). The fragment sizes determined by the two analysis methods were highly correlated (r(2)=0.98). On-chip T-RFLP analysis was completed within 15 min. T-RFLP profiles of nine hydroponics solution samples were analyzed by multidimensional scaling. Considerable changes and stability in bacterial community structure during hydroponic culture were detected by both analyses. These results show that on-chip T-RFLP analysis can monitor changes in bacterial community structure, as well as conventional T-RFLP analysis. The present results indicate that on-chip T-RFLP analysis is an effective tool for rapid and "on-site" bacterial community profiling in freshwater environments, as well as freshwater used for medical and industrial purposes. PMID:23902975

  2. Enhanced performance in capacitive force sensors using carbon nanotube/polydimethylsiloxane nanocomposites with high dielectric properties

    NASA Astrophysics Data System (ADS)

    Jang, Hyeyoung; Yoon, Hyungsuk; Ko, Youngpyo; Choi, Jaeyoo; Lee, Sang-Soo; Jeon, Insu; Kim, Jong-Ho; Kim, Heesuk

    2016-03-01

    Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased dielectric properties of elastomers and simple sensor structure. We rationally design dielectric elastomers based on alkylamine modified-multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composites, which have a higher dielectric constant than pure PDMS. The alkylamine-MWCNTs show excellent dispersion in a PDMS matrix, thus leading to enhanced and reliable dielectric properties of the composites. A force sensor array fabricated with alkylamine-MWCNT/PDMS composites presents an enhanced response due to the higher dielectric constant of the composites than that of pure PDMS. This study is the first to report enhanced performance of capacitive force sensors by modulating the dielectric properties of elastomers. We believe that the disclosed strategy to improve the sensor performance by increasing the dielectric properties of elastomers has great potential in the development of capacitive force sensor arrays that respond to various input forces.Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased

  3. Contamination-resistant silica antireflective coating with closed ordered mesopores.

    PubMed

    Sun, Jinghua; Zhang, Qinghua; Ding, Ruimin; Lv, Haibing; Yan, Hongwei; Yuan, Xiaodong; Xu, Yao

    2014-08-21

    Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability. PMID:25000419

  4. Systematic characterization of degas-driven flow for poly(dimethylsiloxane) microfluidic devices

    DOE PAGESBeta

    Liang, David Y.; Tentori, Augusto M.; Dimov, Ivan K.; Lee, Luke P.

    2011-01-01

    Degas-driven flow is a novel phenomenon used to propel fluids in poly(dimethylsiloxane) (PDMS)-based microfluidic devices without requiring any external power. This method takes advantage of the inherently high porosity and air solubility of PDMS by removing air molecules from the bulk PDMS before initiating the flow. The dynamics of degas-driven flow are dependent on the channel and device geometries and are highly sensitive to temporal parameters. These dependencies have not been fully characterized, hindering broad use of degas-driven flow as a microfluidic pumping mechanism. Here, we characterize, for the first time, the effect of various parameters on the dynamics ofmore » degas-driven flow, including channel geometry, PDMS thickness, PDMS exposure area, vacuum degassing time, and idle time at atmospheric pressure before loading. We investigate the effect of these parameters on flow velocity as well as channel fill time for the degas-driven flow process. Using our devices, we achieved reproducible flow with a standard deviation of less than 8% for flow velocity, as well as maximum flow rates of up to 3 nL/s and mean flow rates of approximately 1-1.5 nL/s. Parameters such as channel surface area and PDMS chip exposure area were found to have negligible impact on degas-driven flow dynamics, whereas channel cross-sectional area, degas time, PDMS thickness, and idle time were found to have a larger impact. In addition, we develop a physical model that can predict mean flow velocities within 6% of experimental values and can be used as a tool for future design of PDMS-based microfluidic devices that utilize degas-driven flow.« less

  5. Restraining non-specific adsorption of protein using Parylene C-caulked polydimethylsiloxane.

    PubMed

    Liu, Yaoping; Zhang, Lingqian; Wu, Wengang; Zhao, Meiping; Wang, Wei

    2016-03-01

    Non-specific adsorption (NSA) of proteins on surface is a critical issue in polydimethylsiloxane (PDMS)-based microfluidics, which may either considerably decrease the efficiency of a continuous flow reaction or cause a large background noise in a heterogeneous sensing. This work introduced a new method to restrain NSA of protein by caulking PDMS with Parylene C, i.e., forming a Parylene C-caulked PDMS (pcPDMS) surface. The caulking depth of Parylene C inside PDMS matrix was characterized by laser scanning confocal microscopy based on a detectable autofluorescence intensity difference between Parylene C and PDMS after being annealed at 270 °C for 2 h in nitrogen. NSA of bovine serum albumin (BSA) on the inner surfaces of PDMS and pcPDMS microchannels was experimentally compared. The results indicated that the adsorbed BSA on the pcPDMS surface were 35.2% of that on the pristine PDMS surface after the BSA solution flowing through the microchannels at a flow rate of 2000 nL/min, a typical scenario of the continuous flow reaction. In a case mimicking the heterogeneous sensing, after a 60 min washing of phosphate buffered saline flow on a pre-saturated BSA adsorbed surface, the residual BSA on the pcPDMS surface was only 4.5% of that on the pristine PDMS surface. Adsorption/desorption coefficients of BSA on the PDMS and the pcPDMS surfaces were extracted from the experimental results based on the first-order Langmuir model, which indicated that the pcPDMS has a lower adsorption coefficient (Ka ) and a higher desorption coefficient (Kd ), compared to those of the pristine PDMS. A preliminary experiment also indicated that Taq polymerase kept 93.0% activity after flowing through a pcPDMS microchannel, while only 28.9% activity was left after passing a pristine PDMS microchannel under the same operation condition. PMID:27158294

  6. A 2-axis Polydimethylsiloxane (PDMS) based electromagnetic MEMS scanning mirror for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kim, Sehui; Lee, Changho; Kim, Jin Young; Lim, Geunbae; Kim, Jeehyun; Kim, Chulhong

    2016-03-01

    Optical coherence tomography (OCT) is a noninvasive imaging tool for visualizing cross-sectional images of biological tissues on a microscale. Various microelectromechanical system (MEMS) techniques have been applied to OCT for endoscopic catheters and handheld probes. Despite having several advantages such as compact sizes and high speeds for real-time imaging, the complexities of the fabrication processes and relatively high costs were bottlenecks for fast clinical translation and commercialization of the earlier MEMS scanners. To overcome these issues, we developed a 2-axis polydimethylsiloxane (PDMS)-based electromagnetic MEMS scanning mirror based on flexible, cost-effective, and handleable PDMS. The size of this MEMS scanner was 15 × 15 × 15 mm3. To realize the characteristics of the scanner, we obtained the DC/AC responses and scanning patterns. The measured maximum scanning angles were 16.6° and 11.6° along the X and Y axes, respectively. The resonance frequencies were 82 and 57 Hz along the X and Y axes, respectively. The scanning patterns (raster and Lissajous scan patterns) are also demonstrated by controlling the frequency and amplitude. Finally, we showed the in vivo 2D-OCT images of human fingers by using a spectral domain OCT system with a PDMSbased MEMS scanning mirror. We then reconstructed the 3D images of human fingers. The obtained field of view was 8 × 8 mm2. The PDMS-based MEMS scanning mirror has the potential to combine other optical modalities and be widely used in preclinical and clinical translation research.

  7. fs- and ns-laser processing of polydimethylsiloxane (PDMS) elastomer: Comparative study

    NASA Astrophysics Data System (ADS)

    Stankova, N. E.; Atanasov, P. A.; Nedyalkov, N. N.; Stoyanchov, T. R.; Kolev, K. N.; Valova, E. I.; Georgieva, J. S.; Armyanov, St. A.; Amoruso, S.; Wang, X.; Bruzzese, R.; Grochowska, K.; Śliwiński, G.; Baert, K.; Hubin, A.; Delplancke, M. P.; Dille, J.

    2015-05-01

    Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial as encapsulation and/or as substrate insulator carrier for long term neural implants because of its remarkable properties. Femtosecond (λ = 263 and 527 nm) and nanosecond (266 and 532 nm) laser processing of PDMS-elastomer surface, in air, is investigated. The influence of different processing parameters, including laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses, on the surface activation and the surface morphology are studied. High definition tracks and electrodes are produced. Remarkable alterations of the chemical composition and structural morphology of the ablated traces are observed in comparison with the native material. Raman spectra illustrate well-defined dependence of the chemical composition on the laser fluence, pulse duration, number of pulses and wavelength. An extra peak about ∼512-518 cm-1, assigned to crystalline silicon, is observed after ns- or visible fs-laser processing of the surface. In all cases, the intensities of Sisbnd Osbnd Si symmetric stretching at 488 cm-1, Sisbnd CH3 symmetric rocking at 685 cm-1, Sisbnd C symmetric stretching at 709 cm-1, CH3 asymmetric rocking + Sisbnd C asymmetric stretching at 787 cm-1, and CH3 symmetric rocking at 859 cm-1, modes strongly decrease. The laser processed areas are also analyzed by SEM and optical microscopy. Selective Pt or Ni metallization of the laser processed traces is produced successfully via electroless plating. The metallization process is not sensitive with respect to the time interval after the laser treatment. DC resistance is measured to be as low as 0.5 Ω mm-1. Our results show promising prospects with respect to use such a laser-based method for micro- or nano-fabrication of PDMS devices for MEMS and NEMS.

  8. One-step surface modification of poly(dimethylsiloxane) by undecylenic acid

    NASA Astrophysics Data System (ADS)

    Zhou, Jinwen; McInnes, Steven J. P.; Md Jani, Abdul Mutalib; Ellis, Amanda V.; Voelcker, Nicolas H.

    2008-12-01

    Poly(dimethylsiloxane) (PDMS) is a popular material for microfluidic devices due to its relatively low cost, ease of fabrication, oxygen permeability and optical transmission characteristics. However, its highly hydrophobic surface is still the main factor limiting its wide application, in particular as a material for biointerfaces. A simple and rapid method to form a relatively stable hydrophilised PDMS surface is reported in this paper. The PDMS surface was treated with pure undecylenic acid (UDA) for 10 min, 1 h and 1 day at 80 °C in a sealed container. The effects of the surface modification were investigated using water contact angle (WCA) measurements, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), and streaming zeta-potential analysis. The water contact angle of 1 day UDAmodified PDMS was found to decrease from that of native PDMS (110 °) to 75 °, demonstrating an increase in wettability of the surface. A distinctive peak at 1715 cm-1 in the FTIR-ATR spectra after UDA treatment was representative of carboxylation of the PDMS surface. The measured zeta-potential (ζ) at pH 4 changed from -27 mV for pure PDMS to -19 mV after UDA treatment. In order to confirm carboxylation of the surface visually, Lucifer Yellow CH fluorescence dye was reacted via a condensation reaction to the 1 day UDA modified PDMS surface. Fluorescent microscopy showed Lucifer Yellow CH fluorescence on the carboxylated surface, but not on the pure PDMS surface. Stability experiments were also performed showing that 1 day modified UDA samples were stable in both MilliQ water at 50 °C for 17 h, and in a desiccator at room temperature for 19.5 h.

  9. Field-effect flow control in a polydimethylsiloxane-based microfluidic system.

    PubMed

    Buch, J S; Wang, P C; DeVoe, D L; Lee, C S

    2001-10-01

    The application of the field-effect for direct control of electroosmosis in a polydimethylsiloxane (PDMS)-based microfluidic system, constructed on a silicon wafer with a 2.0 microm electrically insulating layer of silicon dioxide, is demonstrated. This microfluidic system consists of a 2.0 cm open microchannel fabricated on a PDMS slab, which can reversibly adhere to the silicon wafer to form a hybrid microfluidic device. Aside from mechanically serving as a robust bottom substrate to seal the channel and support the microfluidic system, the silicon wafer is exploited to achieve field-effect flow control by grounding the semiconductive silicon medium. When an electric field is applied through the channel, a radial electric potential gradient is created across the silicon dioxide layer that allows for direct control of the zeta potential and the resulting electroosmotic flow (EOF). By configuring this microfluidic system with two power supplies at both ends of the microchannel, the applied electric potentials can be varied for manipulating the polarity and the magnitude of the radial electric potential gradient across the silicon dioxide layer. At the same time, the longitudinal potential gradient through the microchannel, which is used to induce EOF, is held constant. The results of EOF control in this hybrid microfluidic system are presented for phosphate buffer at pH 3 and pH 5. It is also demonstrated that EOF control can be performed at higher solution pH of 6 and 7.4 by modifying the silicon wafer surface with cetyltrimethylammonium bromide (CTAB) prior to assembly of the hybrid microfluidic system. Results of EOF control from this study are compared with those reported in the literature involving the use of other microfluidic devices under comparable solution conditions. PMID:11700719

  10. Effect of pendent chains on the interfacial properties of thin polydimethylsiloxane (PDMS) networks.

    PubMed

    Landherr, Lucas J T; Cohen, Claude; Archer, Lynden A

    2011-05-17

    The interfacial properties of end-linked polydimethylsiloxane (PDMS) films on silicon are examined. Thin cross-linked PDMS films (∼10 μm thick) were synthesized over a self-assembled monolayer supported on a silicon wafer. By systematically varying the concentration of monofunctional PDMS in a mixture with telechelic precursor molecules, structures ranging from near-ideal elastic networks to poorly cross-linked networks composed of a preponderance of dangling/pendent chains were synthesized. Lateral force microscopy (LFM) employing bead probes was used to quantify the effect of network structure on the interfacial friction coefficient and residual force. Indentation measurements employing an AFM in force mode were used to characterize the elastic modulus and the pull-off force for the films as a function of pendent chain content. These measurements were complemented with conventional mechanical rheometry measurements on similar thick network films to determine their bulk rheological properties. All networks studied manifested interfacial friction coefficients substantially lower than that of bare silicon. PDMS networks with the lowest pendent chain content displayed friction coefficients close to 1 order of magnitude lower than that of bare silicon, whereas networks with the highest pendent chain content manifested friction coefficients about 3 times lower than that of bare silicon. At intermediate sliding velocities, a crossover in the interfacial friction coefficient was observed, wherein cross-linked PDMS films with the least amount of pendent chains exhibit the highest friction coefficient. These observations are discussed in terms of the structure of the films and relaxation dynamics of elastic strands and dangling chains in tethered network films. PMID:21495649

  11. A laser ultrasound transducer using carbon nanofibers–polydimethylsiloxane composite thin film

    SciTech Connect

    Hsieh, Bao-Yu; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning; Zhu, Jiadeng; Zhang, Xiangwu

    2015-01-12

    The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10{sup −3 }Pa/(W/m{sup 2}), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.

  12. Theoretical study of the surface properties of poly(dimethylsiloxane) and poly(tetrafluoroethylene).

    PubMed

    Michalkova, Andrea; Tulyani, Sonia; Beals, James; Leszczynski, Jerzy

    2012-01-01

    Molecular dynamics (MD) simulations of poly(dimethylsiloxane) (PDMS) and poly(tetrafluoroethylene) (PTFE) were carried out to determine their surface properties and energies. This study helps to gain better insight into the molecular modeling of PDMS and PTFE, in particular how different approaches affect calculations of surface energy. Current experimental and theoretical data were used to further understand the surface properties of PDMS and PTFE as well as to validate and verify results obtained from the combination of density functional theory (DFT) calculations (including periodic boundary conditions) and MD simulations. Detailed analysis of the structure and electronic properties (by calculation of the projected density of states) of the bulk and surface models of PDMS and PTFE was performed. The sensitivity of the surface energy calculation of these two polymers to the chemistry and model preparation was indicated. The balance between the molecular density, weight (which also reflects bond orientation in the surface region), bond flexibility, and intramolecular interactions including bond stretching was revealed to govern the results obtained. In modeling, the structural organization of polymer near a given surface (types and number of end groups and broken bonds due to application of different cut offs of the periodic structure) also significantly affects the final results. Besides the structural differences, certain simulation parameters, such the DFT functionals and simulation boxes utilized, play an important role in determining surface energy. The models used here were shown to be sufficient due to their good agreement with experimental and other theoretical data related to surface properties and surface energies. PMID:21523541

  13. Polydimethylsiloxane Core-Polycaprolactone Shell Nanofibers as Biocompatible, Real-Time Oxygen Sensors

    PubMed Central

    Xue, Ruipeng; Behera, Prajna; Xu, Joshua; Viapiano, Mariano S.; Lannutti, John J.

    2014-01-01

    Real-time, continuous monitoring of local oxygen contents at the cellular level is desirable both for the study of cancer cell biology and in tissue engineering. In this paper, we report the successful fabrication of polydimethylsiloxane (PDMS) nanofibers containing oxygen-sensitive probes by electrospinning and the applications of these fibers as optical oxygen sensors for both gaseous and dissolved oxygen. A protective ‘shell’ layer of polycaprolactone (PCL) not only maintains the fiber morphology of PDMS during the slow curing process but also provides more biocompatible surfaces. Once this strategy was perfected, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) (Ru(dpp)) and platinum octaethylporphyrin (PtOEP) were dissolved in the PDMS core and the resulting sensing performance established. These new core-shell sensors containing different sensitivity probes showed slight variations in oxygen response but all exhibited excellent Stern-Volmer linearity. Due in part to the porous nature of the fibers and the excellent oxygen permeability of PDMS, the new sensors show faster response (<0.5 s) −4–10 times faster than previous reports – than conventional 2D film-based oxygen sensors. Such core-shell fibers are readily integrated into standard cell culture plates or bioreactors. The photostability of these nanofiber-based sensors was also assessed. Culture of glioma cell lines (CNS1, U251) and glioma-derived primary cells (GBM34) revealed negligible differences in biological behavior suggesting that the presence of the porphyrin dyes within the core carries with it no strong cytotoxic effects. The unique combination of demonstrated biocompatibility due to the PCL ‘shell’ and the excellent oxygen transparency of the PDMS core makes this particular sensing platform promising for sensing in the context of biological environments. PMID:25006274

  14. Systematic characterization of degas-driven flow for poly(dimethylsiloxane) microfluidic devices

    SciTech Connect

    Liang, David Y.; Tentori, Augusto M.; Dimov, Ivan K.; Lee, Luke P.

    2011-01-01

    Degas-driven flow is a novel phenomenon used to propel fluids in poly(dimethylsiloxane) (PDMS)-based microfluidic devices without requiring any external power. This method takes advantage of the inherently high porosity and air solubility of PDMS by removing air molecules from the bulk PDMS before initiating the flow. The dynamics of degas-driven flow are dependent on the channel and device geometries and are highly sensitive to temporal parameters. These dependencies have not been fully characterized, hindering broad use of degas-driven flow as a microfluidic pumping mechanism. Here, we characterize, for the first time, the effect of various parameters on the dynamics of degas-driven flow, including channel geometry, PDMS thickness, PDMS exposure area, vacuum degassing time, and idle time at atmospheric pressure before loading. We investigate the effect of these parameters on flow velocity as well as channel fill time for the degas-driven flow process. Using our devices, we achieved reproducible flow with a standard deviation of less than 8% for flow velocity, as well as maximum flow rates of up to 3 nL/s and mean flow rates of approximately 1-1.5 nL/s. Parameters such as channel surface area and PDMS chip exposure area were found to have negligible impact on degas-driven flow dynamics, whereas channel cross-sectional area, degas time, PDMS thickness, and idle time were found to have a larger impact. In addition, we develop a physical model that can predict mean flow velocities within 6% of experimental values and can be used as a tool for future design of PDMS-based microfluidic devices that utilize degas-driven flow.

  15. Effect of meta-carborane on segmental dynamics in a bimodal Poly(dimethylsiloxane) network

    SciTech Connect

    Lewicki, J; Maxwell, R S; Patel, M; Herberg, J; Swain, A C; Liggat, J; Pethrick, R

    2008-06-11

    Bimodal networks of polydimethylsiloxane (PDMS) filled with varying amounts of icosahedral meta-carborane (m-CB) have been developed and characterized by broadband dielectric spectroscopy (BDS) and static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR). Both BDS and MQ NMR showed evidence for a decrease in the polymer chain dynamics. BDS spectra quantified a normal-mode relaxation near 40 Hz at 40 C. The frequency maximum observed for filled samples decreased with increasing m-CB content until contents greater than 5 wt. %. The width of the relaxation spectrum increased with the addition of small quantities of filler and decreased with filler contents greater that 5 wt. %. Agglomeration effects were observed at loadings greater than 5 wt % as manifest by the onset of low frequency Maxwell-Wagner-Sillars (MWS) processes. The MQ NMR data allowed the characterization of distributions of the residual dipolar couplings, <{Omega}{sub d}> and thus in the dynamic order parameter, Sb, consistent with the bimodal network architecture expected from the synthesis protocol used. Upon addition of less than 10 wt.% m-CB filler, the mean <{Omega}{sub d}> for the longer chains increased by 46% and the width of the distribution increased by 33%. The mean <{Omega}{sub d}> for the shorter chains increased by much less, indicative of preferential dispersion of the filler particles in the long chain domains of the network structure. We conclude that the mechanism of reinforcement is likely a free volume space filling at low loadings transitioning to complex molecular filler and polymer chain interaction phenomena at higher loadings.

  16. Poly(dimethylsiloxane) cross-linked carbon paste electrodes for microfluidic electrochemical sensing.

    PubMed

    Sameenoi, Yupaporn; Mensack, Meghan M; Boonsong, Kanokporn; Ewing, Rebecca; Dungchai, Wijitar; Chailapakul, Orawan; Cropek, Donald M; Henry, Charles S

    2011-08-01

    Recently, the development of electrochemical biosensors as part of microfluidic devices has garnered a great deal of attention because of the small instrument size and portability afforded by the integration of electrochemistry in microfluidic systems. Electrode fabrication, however, has proven to be a major obstacle in the field. Here, an alternative method to create integrated, low cost, robust, patternable carbon paste electrodes (CPEs) for microfluidic devices is presented. The new CPEs are composed of graphite powder and a binder consisting of a mixture of poly(dimethylsiloxane) (PDMS) and mineral oil. The electrodes are made by filling channels molded in previously cross-linked PDMS using a method analogous to screen printing. The optimal binder composition was investigated to obtain electrodes that were physically robust and performed well electrochemically. After studying the basic electrochemistry, the PDMS-oil CPEs were modified with multi-walled carbon nanotubes (MWCNT) and cobalt phthalocyanine (CoPC) for the detection of catecholamines and thiols, respectively, to demonstrate the ease of electrode chemical modification. Significant improvement of analyte signal detection was observed from both types of modified CPEs. A nearly 2-fold improvement in the electrochemical signal for 100 μM dithiothreitol (DTT) was observed when using a CoPC modified electrode (4.0 ± 0.2 nA (n = 3) versus 2.5 ± 0.2 nA (n = 3)). The improvement in signal was even more pronounced when looking at catecholamines, namely dopamine, using MWCNT modified CPEs. In this case, an order of magnitude improvement in limit of detection was observed for dopamine when using the MWCNT modified CPEs (50 nM versus 500 nM). CoPC modified CPEs were successfully used to detect thiols in red blood cell lysate while MWCNT modified CPEs were used to monitor temporal changes in catecholamine release from PC12 cells following stimulation with potassium. PMID:21698305

  17. Surface-enhanced Raman scattering (SERS) characterization of trace organoarsenic antimicrobials using silver/polydimethylsiloxane nanocomposites.

    PubMed

    Olavarría-Fullerton, Jenifier; Wells, Sabrina; Ortiz-Rivera, William; Sepaniak, Michael J; De Jesús, Marco A

    2011-04-01

    Organoarsenic drugs such as roxarsone and 4-arsanilic acid are poultry feed additives widely used in US broilers to prevent coccidosis and to enhance growth and pigmentation. Despite their veterinary benefits there has been growing concern about their use because over 90% of these drugs are released intact into litter, which is often sold as a fertilizing supplement. The biochemical degradation of these antimicrobials in the litter matrix can release significant amounts of soluble As(III) and As(V) to the environment, representing a potential environmental risk. Silver/polydimethylsiloxane (Ag/PDMS) nanocomposites are a class of surfaceenhanced Raman scattering (SERS) substrates that have proven effective for the sensitive, reproducible, and field-adaptable detection of aromatic acids in water. The work presented herein uses for the first time Ag/PDMS nanocomposites as substrates for the detection and characterization of trace amounts of roxarsone, 4-arsanilic acid, and acetarsone in water. The results gathered in this study show that organoarsenic species are distributed into the PDMS surface where the arsonic acid binds onto the embedded silver nanoparticles, enhancing its characteristic 792 cm(-1) stretching band. The chemisorption of the drugs to the metal facilitates its detection and characterization in the parts per million to parts per billion range. An extensive analysis of the distinct spectroscopic features of each drug is presented with emphasis on the interactions of the arsonic acid, amino, and nitro groups with the metal surface. The benefits of SERS based methods for the study of arsenic drugs are also discussed. PMID:21396190

  18. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2012-2014).

    PubMed

    Breadmore, Michael C; Tubaon, Ria Marni; Shallan, Aliaa I; Phung, Sui Ching; Abdul Keyon, Aemi S; Gstoettenmayr, Daniel; Prapatpong, Pornpan; Alhusban, Ala A; Ranjbar, Leila; See, Hong Heng; Dawod, Mohamed; Quirino, Joselito P

    2015-01-01

    One of the most cited limitations of capillary (and microchip) electrophoresis is the poor sensitivity. This review continues to update this series of biannual reviews, first published in Electrophoresis in 2007, on developments in the field of on-line/in-line concentration methods, covering the period July 2012-July 2014. It includes developments in the field of stacking, covering all methods from field-amplified sample stacking and large-volume sample stacking, through to ITP, dynamic pH junction, and sweeping. Attention is also given to on-line or in-line extraction methods that have been used for electrophoresis. PMID:25330057

  19. Capillary-driven self-assembly of microchips on oleophilic/oleophobic patterned surface using adhesive droplet in ambient air

    NASA Astrophysics Data System (ADS)

    Chang, Bo; Sariola, Veikko; Aura, Susanna; Ras, Robin H. A.; Klonner, Maria; Lipsanen, Harri; Zhou, Quan

    2011-07-01

    This letter describes a capillary-driven self-assembly technique using oleophilic/oleophobic patterned surface and adhesive in ambient air environment. We use a topographical microstructure of porous ormocer functionalized with a fluorinated trichlorosilane for the oleophobic area and gold patterns for the oleophilic area. The resulted oleophilic/oleophobic patterns show significant wettability contrast for adhesive (Delo 18507), with a contact angle of 119° on oleophobic part and 53° on the oleophilic part. Self-alignment of SU-8 microchips on the oleophilic/oleophobic patterns has been demonstrated. The results provide a promising solution for self-alignment of microparts using commercial adhesives in ambient air environment.

  20. Low-power 100-ps microchip laser amplified by a two-stage Nd:YVO4 amplifier module

    NASA Astrophysics Data System (ADS)

    Agnesi, Antonio; Carrà, Luca; Pirzio, Federico; Reali, Giancarlo

    2012-12-01

    We report the amplification of a low-power 4-mW microchip Nd:YVO4 laser at 1064 nm, passively Q-switched with a semiconductor saturable absorber mirror (SESAM). An end-pumped two-stage amplifier module with small-signal gain of 56 dB has been designed to boost the power, generating 6 W at 550 kHz with 100-ps pulses and M 2 = 1.2. Second-harmonic generation in critically phase-matched LBO yielded 3 W at 532 nm, with pulse stability comparable to that of the fundamental frequency.