18 research outputs found
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Superconducting wires
The requirement of high critical current density has prompted extensive research on ceramic processing of high-T/sub c/ superconductors. An overview of wire fabrication techniques and the limitations they impose on component design will be presented. The effects of processing on microstructure and critical current density will also be discussed. Particle alignment has been observed in extruded samples which is attributed to high shear stresses during plastic forming. Composites of superconductor and silver in several configurations have been made with little deleterious effect on the superconducting properties. 35 refs., 2 figs., 1 tab
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Effect of Fabrication Factors on Performance of Screen‐Printed/Laser Micromachined Electrochemical Nanovials
Electrochemical vials with volumes of 2.6 nL and embedded working and reference electrodes have been fabricated by coupling screen‐printing (thick‐film) technology with excimer laser micromachining. The processing parameters were varied to determine their effect on the resulting nanocell. The fabricated systems were analyzed by resistance measurements, surface profilometry, and SEM. The performance of the electrochemical nanovials was evaluated by cyclic voltammetry using hexaamineruthenium(III) chloride. The current limits of thick‐film fabrication were approached in creating very small nanocells using the methods described. The functioning small volume electrochemical cells gave voltammograms that were either peak‐shaped or sigmoidal. The shape of the voltammogram corresponded to the electrochemical surface area determined by chronoamperometry
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Electrochemistry in nanovials fabricated by combining screen printing and laser micromachining
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Microfabrication of screen-printed nanoliter vials with embedded surface-modified electrodes
A self-contained ion-selective sensing system within a nanoliter-volume vial has been developed by integrating screen printing, laser ablation, and molecular imprinting techniques. Screen printing and laser ablation are used in tandem to fabricate nanoliter-volume vials with carbon and Ag/AgCl ring electrodes embedded in the sidewalls. Using multisweep cyclic voltammetry, the surface of the carbon electrode can be modified with a polypyrrole film. By polymerizing pyrrole in the presence of nitrate, pores complementary to the nitrate anion in size, shape, and charge distribution are formed in the resulting film. Electrochemical cells modified with this nitrate-imprinted polypyrrole film show a near-Nernstian response to nitrate, and excellent reproducibility. The integration of molecular recognition and electrochemical response in the nanoliter vials is demonstrated by the detection of as little as 0.36 ng nitrate in nanoliter-volume samples. The integration of tailored molecular recognition within nanoliter vials via established fabrication and imprinting protocols should result in a number of nanosensor devices with applications in BioMEMS and micro total analysis systems