Stock material or miscellaneous articles – Hollow or container type article – Glass – ceramic – or sintered – fused – fired – or calcined metal...
Reexamination Certificate
2000-02-03
2003-05-13
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Glass, ceramic, or sintered, fused, fired, or calcined metal...
C428S690000, C428S034100, C428S034400, C372S053000
Reexamination Certificate
active
06562424
ABSTRACT:
The present invention relates to photochemical sensors and methods for the production thereof.
BACKGROUND OF INVENTION
More particularly, the present invention relates to an indicator dye nanoporous photochemical sensor composite glass films and processes for the preparation thereof, as well as to the use thereof in the preparation of a fiber optic and/or wave-guiding photochemical sensor for detecting environmental impurities.
The present invention enables the preparation of stable, multi-use remote sensors for detection systems for environmental impurities which allow monitoring in situ of traces of impurities such as ammonia, acid rain and bases in the atmosphere, the water and the ground, and chlorinated hydrocarbons in ground waters and soils, based on the introduction of indicator dyes into a novel composite glass film from which sensitive waveguides are fabricated.
The concept of applying optical guides and fiber optical sensors to the detection of various environmental impurities is not new, and has been pursued for over a decade. (See, e.g., W. R. Seitz, “Chemical Sensors Based on fiber Optics,”
Anal. Chem.,
Vol. 56, p. 16A (1984); D. W. Luebbers and N. Opitz, “Optical Fluorescence Sensors for Continuous Measurements of Chemical Concentration in Biological Systems,”
Sensors Actuators,
Vol. 4, p. 641 (1983); and E. J. Poziomek, “Fiber Optic Sensors, A Review,”
Proc. of the Third Biennial Dept. of Defense Fiber Optics Conference,
pp. 115-119, McLean, Va., U.S.A. (March 1992).)
The use of optical fibers for remote spectroscopy predates the use of fibers in communication systems, and continues to be an important technique in environmental, biomedical and process-control sensing. Recent progress in fiber optic chemical sensing, including the development of optically active sensors, intrinsically sensitive fibers, new sensor chemistries, and sensors based on integrated optic devices, has greatly expanded the range of application of chemical and environmental fiber optic sensors.
Two main configurations can be considered, using either the end fiber or the evanescent wave technique. In the first case, a dye-doped material (polymer or porous glass) is attached to the end of an optical fiber which is only used to relay the sensitive dye fluorescence (or absorption) signal. In the second case, the fiber itself becomes part of the sensing element, which consists of a dye-doped cladding coated onto the fiber core. The evanescent field of a guided radiation can excite the dye, which interacts selectively with the analyte and modulates the light signal. This approach offers a shorter response time and a distributed sensing; a spatial profile of the analyte concentration is provided along the length of the fiber.
Though it may not be apparent in first examination of current work on development of fiber optic sensors for hazardous materials, much of this research involves immobilization of the indicator molecules. Examples of substrates examined recently include porous glass and porous polymers (see, e.g., M. Bocci, F. Baldwin and S. Bracci, “Spectroscopic Behavior of Acid-Base Indicators after Immobilization on Glass Supports,”
Appl. Spectrosc.,
Vol. 45, No. 9, pp. 1508-1515 (1991); and M. B. Tabacco, Q. Zhou, K. Rosenblum and M. R. Shahriari, “Chemical Sensors for Hazardous Waste Monitoring,”
Proc. of the Second International Symposium on Field
-
Screening Methods for Hazardous Wastes and Toxic Chemicals,
U.S. Environmental Protection Agency, Las Vegas, Nev., U.S.A. (February 1991)); M. Bocci, F. Baldinin and S. Bracci, “Spectroscopic Behavior of Acid-Base Indicators after Immobilization on Glass Supports,”
Appl. Spectrosc.,
Vol. 45, No. 9, pp. 1508-1515 (1991); and C. Rottman, M. Ottolengi, R. Zusman, et al., “Doped Sol-Gel Glasses as pH Sensors,”
Matt. Lett.,
Vol. 13, pp. 293-298 (1992)); linear-chain, rigid-rod polymers (W. P. Carey and B. S. Jorgensen, “Optical Sensors for High Acidities Based on Fluorescent Polymers,”
Appl. Spectrosc.,
Vol. 45, No. 5, pp. 834-838 (1991)); polybenzimidazol and Formvar
R
(L. C. Baylor and P. E. O'Rourke, “Fiber Optic pH Sensors,”
NUCL
89,
Abstracts of Papers,
201st American Chemical Society National Meeting, Atlanta, Ga., U.S.A. (April 1991)); cellulose acetate (T. P. Jones, S. J. Coldron, W. J. Deninger and M. D. Porter, “A Field-Deployable Dual Wavelength Fiber Optic pH Sensor Instrument Based on Solid-State Optical and Electrical Components,”
App. Spectrosc.,
Vol. 45, No. 8, pp. 1271-1276 (1991)); quartz powder (M. F. McCurley and W. R. Seitz, “Fiber Optic Chemical Sensors Based on Polymer Swelling,”
ANYL
61,
Abstracts of Papers,
201st American Chemical Society National Meeting, Atlanta, Ga., U.S.A. (April 1991)); poly(vinyl alcohol) with oxiran group (J. Reichert, R. Czolk, W. Sellien and A. J. Ache, “Chemical Sensors in Environmental Analysis: Ammonium and Cadmium Sensors,”
NATO ASSI Ser.,
Ser G 1991, pp. 195-211 (
Chem. Abstr.
115:84318p)); dimethyl silicone powder (S. M. Barnard and D. R. Walt, “Fiber Optic Organic Vapor Sensor,”
Environ. Sci. Techn.,
Vol. 25, No. 7, pp. 1301-1304 (1991)); and cellulose triacetate (C. Jian and W. R. Seitz, “Membrane for In Situ Optical Detection of Organic Nitro Compounds Based on Fluorescence Quenching,”
Anal. Chim. Acta,
Vol. 237, No. 2, pp. 265-271 (1991)).
Ethyl cellulose has been proposed as a coating standard for mass sensors, but could be used as a “standard” substrate for fiber optic sensors as well (see, e.g., E. J. Poziomek, J. Li, H. Wohitjen and N. L. Jarvis, “Ethyl Cellulose as a Coating Standard for Mass Sensors,”
Third International Symposium on Field Screening Methods for Hazardous Wastes and Toxic Chemicals,
Las Vegas, Nev., U.S.A. (February 1993)).
However, design of immobilized indicator materials, and meeting needs of sensitivity and selectivity are not trivial, as pointed out and explained by E. J. Poziomek, “Technology Barriers in the Development of Fiber Optic and Other Chemical Sensors for Field Screening,”
Oak Ridge National Laboratory Life Sciences Symposium,
Gatlinburg, Tenn., U.S.A. (May 1990), published in
Hazardous Waste Site Investigation,
R. B. Gammage and B. A. Berven, Eds., Lewis Publishers, Ann Arbor, Mich., U.S.A. (1992).
Furthermore, there is a severe drawback in incorporating the organic indicator dyes into the traditional host matrices. Depending on the nature of the polymer, the sensor probe is not necessarily inert with respect to the dye, as free radicals tend to be formed under photo-excitation. These radicals tend to strongly reduce the absorption and luminescence characteristics of the dyes. The polymeric matrices may also provide a reductive atmosphere, which will react with the photo-excited states of the dyes and will change their chemical constitution with time. It is therefore of vital interest to develop inert, highly transparent host matrices which are stable and which can be used for remote sensors for environmental and biological impurities.
Purely inorganic matrices, on the other hand, furnish too polar environment for entrapped organic indicator molecules, which may cause them to agglomerate at high concentrations and thus prevent high sensitivity.
In 1990, the present inventor and others published an article, entitled “Oxazine-170 in Sol-Gel Glass and PMMA Films as a Reversible Optical Waveguide Sensor for Ammonia and Acids,” (V. Chernyak, R. Reisfeld, R. Gvishi and D. Venezky,
Sensors and Materials,
Vol. 2, No. 2 pp. 117-126 (1990)). In this article, there were described sensors for ammonia and acids based on Oxazine-170 dye, incorporated into sol-gel glasses prepared from tetraethoxysilane. However, the kinetics of the ammonia diffusion was too slow to be used for practical purposes, if the films were not thin enough. On the other hand, Oxazine-170, incorporated into polymethylmethacrylate (PMMA) gave a very good response; however, the sensor was not stable enough and deteriorated quickly.
Earlier in 1993, the present inventor published a further article, entitled “Photochemical SeBased on Malachite G
Reisfeld Renata
Shamrakov Dimitri
Miggins Michael C.
Pyon Harold
Sughrue & Mion, PLLC
Yissum Research Development Company
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