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15 September 1995 Near- and mid-infrared chemical and biological sensors
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Polyaniline has been used as the transducer for an optical sensor by monitoring its evanescent wave spectrum in the near- and mid-IR regions as a function of pH. Cladding on silica and chalcogenide fiber optic cores was replaced with thin films of polyaniline. A low energy electronic transition in the near-IR and vibrational transitions in the mid-IR can be used to predict pH. The near-IR transitions have higher signal-to-noise ratios and are more useful for sensing pH. However, changes in the vibrational transitions observed in the evanescent wave spectra suggest extensive changes in chemical groups as a function of pH. The near-IR evanescent wave sensor was converted into a glucose sensor by immobilizing glucose oxidase on the surface of the polymer. The enzyme converted glucose to gluconic acid and the resulting pH change was used to predict glucose concentrations. Standard errors of prediction for the concentration range of 0 to 20 mM were 0.25 mM for distilled water and 0.8 mM for buffer solutions.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christopher W. Brown, Chi-Shi Chen, and Yue Li "Near- and mid-infrared chemical and biological sensors", Proc. SPIE 2528, Optical and Photonic Applications of Electroactive and Conducting Polymers, (15 September 1995);


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