| A design strategy for developing fiber-optic chemical sensors, FOCS, by combining the advantages of fluorescent indicating chemistries and specific polymer properties is described. This strategy is applied to the preparation of sensors for environmental and medical applications.;FOCS and supporting field-portable instrumentation have been developed that are capable of in situ, continuous measurements of volatile organic compounds in groundwater and soil samples. The sensors are based on the absorption of organic vapors by polymers which results in fluorescence enhancement of an immobilized fluorophor. Laboratory tests and preliminary in situ field data are presented from a jet fuel contamination site.;A novel chemical sensor has been developed using ethylene vinyl acetate as a controlled-release system to deliver reagents to the sensing region of an optical fiber for a homogeneous competitive immunoassay based on fluorescence energy transfer. The technique allows irreversible indicating chemistries to be used in the construction of chemical sensors that can measure continuously for long periods. Data are presented for a model system employing a fluorescein-labeled antibody and Texas Red-labeled immunoglobin G (IgG).;A ratiometric fiber optic pH sensor has been developed by coimmobilizing a pH-sensitive fluorophor and a pH-insensitive fluorophor, to the distal end of an optical fiber. Two distinct emission peaks are produced for ratioing at one excitation wavelength, using nonradiative energy transfer. The sensor has improved calibration stability during daily, continuous, and intermittent use as compared to conventional absolute intensity sensors.;A novel technique has been developed that allows the design of multianaltye FOCS based on the selective photopolymerization of indicating chemistries on the distal face of an imaging-fiber. Data from a sensor that contains three individual pH-sensitive areas are presented. In addition, data are presented of a true multianalyte sensor with pO... |
