As an example, we present the use of pH indicators for the selective and reversible detection of NH3 in air (one relevant gas contributing to bad odors) using gas-sensitive layers dip coated on glass substrates. Our results show that the method can be adapted to detect NH3 concentrations lower than 1 ppm, with measure-to-result times in the range of a few minutes. We demonstrate that the color measurements can be carried out with the optical signals of RGB sensors, without losing quantitative performance.
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K. Schmitt, K. Tarantik, C. Pannek, I. Benito-Altamirano, O. Casals, C. Fàbrega, A. Romano-Rodríguez, J. Wöllenstein, J. D. Prades, "Colorimetric sensor for bad odor detection using automated color correction," Proc. SPIE 10246, Smart Sensors, Actuators, and MEMS VIII, 102461F (2 June 2017);