The development of a chip-based sensor array composed of individually addressable polystyrene-poly(ethylene glycol) and agarose microspheres has been demonstrated. The microspheres are selectively arranged in micromachined cavities localized on silicon wafers. These cavities are created with an anisotropic etch and serve as miniaturized reaction vessels and analysis chambers. A single drop of fluid provides sufficient analysis media to complete approximately 100 assays in these microetch pits. The cavities possess pyramidal pit shapes with trans-wafer openings that allows for both fluid flow through the microreactors/analysis chambers and optical access to the chemically sensitive microspheres. Identification and quantitation of analytes occurs via colorimetric and fluorescence changes to receptor and indicator molecules that are covalently attached to termination sites on the polymeric microspheres. Spectral data are extracted from the array efficiently using a charge-coupled device allowing for the near-real-time digital analysis of complex fluids. The power and utility of this new microbead array detection methodology is demonstrated here for the analysis of complex fluids containing a variety of important classes of analytes including acids, bases, metal cations, metabolic cofactors, and antibody reagents.

1218 Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 1999 0935-9648/99/1410-1218 $ 17.50+.50/0 Adv. Mater. 1999, 11, No. 14 was dried only to about 30 % of its weight before the crosslinking step. A drop of 1 M MgSO4 was added for the crosslinking, and after about 15 min the electrode was equilibrated with aqueous 0.25 M MgSO4 for at least 2 h. The PPy was grown on the polymer gel as described above. The unswelled PEDOT-PSS/PPy electrode was prepared by electropolymerizing pyrrole on an uncrosslinked PEDOT-PSS-coated electrode from acetonitrile solution containing 0.25 M pyrrole and 0.1 M LiClO4 at a constant potential of 0.85 V vs. an Ag/AgCl electrode. The PPy-coated electrode was prepared by growing PPy on a gold electrode under the same conditions as in the case of PEDOT-PSS/PPy electrodes. The electrochemical cell in the supercapacitor geometry for the cyclic voltammetric and the chrono-potentiometric studies was a two-electrode set-up, with two identical electrodes face to face and parallel, in aqueous 1 M Na2SO4. For the swelled-polymer electrodes, i.e., in the cases where high power-density was applied the electrodes were at a fixed separation of 1 mm, whereas in other cases, the distance was about 1 cm. The cells were in ambient atmospheric conditions. The chrono-potentiometric studies of galvanostatic charging±discharging were carried out in the potential range of 0 V to 0.8 V. For calculation of the energy and power densities, the first discharge curve after equilibration of the cell at 0.8 V was analyzed, and the dry mass of the polymeric material on a single electrode was considered. The mass of the PEDOT-PSS was determined from the weight of the dispersion of known concentration that was applied to the electrode. The mass of PPy was calculated from the coulomb of charge passed for its electropolymerization, assuming 2.25 electrons per pyrrole unit are needed for the polymerization of PPy at 25 % doping level.

A unique corrugated-thin-metal-film structure suitable for integration with semiconductor photodetectors, is investigated. For fluorescent spectral monitoring, this structure provides a number of important detection features including fluorescence enhancement for molecules located near the surface of the sensor, excitation wavelength shielding and narrow bandpass filtering of detected wavelengths. Surface dielectrics with chemical or biological-specific properties may also be incorporated into the sensor for additional selectivity.

The thermal diffusivity of a thin organic dye layer deposited atop thin films of the high temperature superconductor YBa2Cu3O7−δ is measured using a pulsed laser flash method. Here, the underlying superconductor acts as a highly sensitive temperature transducer after appropriate conversion of the transient voltage response from 7 ns optical pulses. Film surface temperature decays for several thicknesses of the dye layers were evaluated; these decays exhibited a linear dependence of the time at half temperature maximum versus thickness squared. Three dimensional finite difference modeling was used to study and extract the thermal diffusivity values of the thin organic layers as well as to investigate the transient temperature distributions within the dye and superconductor areas.

A strategy for increasing the wavelength selectivity and responsivity of hybrid dye/superconductor optical sensors is described. Here, reflective 'mirror layers' deposited on the top surface of YBa2Cu3O7-(delta ) thin film devices are used to enhance the optical performance characteristics of such hybrid sensors. Quantification of the wavelength-selectivity for such detector structures is detailed for both dye/high-Tc superconductor and dye/mirror-layer/high-Tc superconductor systems. Optical response studies of the structures suggest that the inclusion of the mirror layer serves to enhance the wavelength-selectivity of the detector. Consequently, only the on-resonance signals captured by the dye layer are effectively sensed by the superconductor element. Measurements of the spectral response properties of the mirror layer-modified hybrid detectors show that energy transfer between the dye and superconducting elements is not diminished by the presence of this reflective layer.

Utilization of the high temperature superconductor, YBa2Cu3O7-delta, in commercial applications is becoming increasingly feasible. Before full advantage of this material can be taken, however, the lifetime, oxygen stability and processability of this ambient reactive superconductor must be improved. Corrosion resistance of YBa2Cu3O7-delta and a cation substituted compound, Y0.6Ca0.4Ba1.6La0.4Cu3O7-delta, were studied and their lifetimes in aqueous environments were determined. Results indicate a dramatic enhancement in the stability against environmental degradation for the cation substituted phase. Important mechanistic factors responsible for the enhanced corrosion resistance of the substituted phase over the parent compound are discussed.

A new method for enhancing the wavelength selectivity and responsivity of hybrid dye/superconductor optical sensors is described. Here, reflective ''mirror layers'' deposited atop the high-temperature superconductor, YBa2Cu3O7-delta, are used to enhance the optical performance characteristics of such hybrid sensors. Quantification of the wavelength selectivity for such detector structures is detailed for both dye/high-T-c superconductor and dye/mirror-layer/high-T-c superconductor systems. Optical studies suggest that the inclusion of the mirror layer serves to enhance the wavelength selectivity by reducing the amount of off-resonance signal generated by the detector. On the other hand, the on-resonance signals captured by the dye layer are effectively sensed by the superconductor element. Measurement of the wavelength-dependent optical responsivity of the mirror-layer-modified. hybrid detectors shows that energy transfer between the dye and superconducting elements is not diminished by the presence of this reflective layer.

This paper describes the design, construction and operation of hybrid dye/superconductor optical sensors. A reflective mirror layer positioned between the dye and superconductor components is used as a means to reject light signals that are not absorbed strongly by the dye. On resonance signals are shown to couple effectively with the underlying superconductor where they evoke measurable responses. These structures form the basis for color selective optical sensors.

A cosubstitution of Ca2+ for Y3+and La3+ for Ba2+ in YBa2Cu3O7−δ is found to improve the corrosion resistance of this high- Tc superconductor. The reactivity characteristics of bulk and thin film samples of Y1−zCazBa2−yLayCu3O7−δ indicate that the corrosion resistance in water environments increases with increasing degree of cation substitution up to z=y=0.4. The composition of Y0.6Ca0.4Ba1.6La0.4Cu3O6.96 with a Tc of 80 K is found to be at least 100 times more stable than YBa2Cu3O6.94. Possible contributing factors that could be responsible for the marked improvement in the corrosion resistance of this high-Tc phase are discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemically Tailored, Corrosion Resistant, High-Tc PhasesJi-Ping Zhou, Steven M. Savoy, Jianai Zhao, David R. Riley, Y. T. Zhu, A. Manthiram, Rung-Kuang Lo, Damon Borich, and John T. McDevittCite this: J. Am. Chem. Soc. 1994, 116, 20, 9389–9390Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://pubs.acs.org/doi/10.1021/ja00099a090https://doi.org/10.1021/ja00099a090research-articleACS PublicationsRequest reuse permissionsArticle Views65Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

High temperature superconductors provide enhanced sensitivity capabilities as chemical/biological agent detectors. State-of-the-art advances in ruggedizing superconducting platforms make them much more robust for field applications. In addition, microminiaturization and advances in refrigeration have enabled the systems engineering of portable, durable, survivable, low power requirement devices. This presentation describes a prototype system employing YBCO (yttrium barium copper oxide) superconducting quantum interference devices (SQUIDS) with specific biolayer detection dye coatings. These devices may be deployed as specific stand-off detectors, or potentially reconfigured as point sensors. A library of pattern recognition algorithms provides the reference template for the system. The human-system interface will provide a 'yes/no' agent confirmation for the environment being queried, and associated confidence value. This prototype detection system has great potential for deployment in support of hostage rescue/rapid response teams, DMAT, and urban search and rescue. The preparation and characterization of a new generation of optical sensors fabricated from high-temperature superconductor (HTSC) thin films is reported herein. These new hybrid devices are fashioned using HTSC thin films which are coated with organic dye overlayers. These systems are shown to respond selectively to those wavelengths which are absorbed strongly by the molecular dye. Methods for fabricating the superconductor element and depositing the dye layer are discussed. Moreover, resistivity versus temperature measurements before and after dye deposition are utilized to characterize these hybrid structures. The unique optical response properties of these hybrid sensors are also detailed.