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Published September 12, 1996 | public
Journal Article Open

Array-Based Vapor Sensing Using Chemically Sensitive, Carbon Black−Polymer Resistors


We describe herein the construction of a simple, low-power, broadly responsive vapor sensor. Carbon black−organic polymer composites have been shown to swell reversibly upon exposure to vapors. Thin films of carbon black−organic polymer composites were deposited across two metallic leads, and swelling-induced resistance changes of the films signaled the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements were constructed, with each element containing the same carbon black conducting phase but a different organic polymer as the insulating phase. The differing gas−solid partition coefficients for the various polymers of the sensor array produced a pattern of resistance changes that can be used to classify vapors and vapor mixtures. This type of sensor array resolved common organic solvents, including molecules of different classes (such as aromatics from alcohols) as well as those within a particular class (such as benzene from toluene and methanol from ethanol). The response of an individual composite to varying concentrations of solvent was consistent with the predictions of percolation theory. Accordingly, significant increases in the signals from array elements were observed for carbon black−polymer composites that were operated near their percolation thresholds.

Additional Information

© 1996 American Chemical Society. Received January 22, 1996. Revised Manuscript Received April 15, 1996. Publication Date (Web): September 12, 1996. This work was supported in part by the Caltech Consortium in Chemistry and Chemical Engineering, the E.I. DuPont de Nemours and Co., Inc. and the Eastman Kodak Co., and by the National Aeronautics and Space Administration and the National Science Foundation, Grant CHE-9202583. M.C.L. acknowledges Caltech for an Arthur Amos Noyes Fellowship and B.J.D. acknowledges the Natural Science and Engineering Research Council of Canada for a 1967 Centennial Fellowship and the O'Brien Foundation for financial support.

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August 19, 2023
August 19, 2023