The testing of a semiconductor-based adsorption modified photosensitive sensor for its response to a volatile organic compound, oxygen, humidity and temperature

A thin-film sensor, composed of a cadmium sulfide layer coated with rhodamine B fluorescent dye on a glass substrate, was tested for changes in photoconductivity due to exposure to different atmospheres. Two different thicknesses (approximately 0.5 and 4.5 μm) of CdS were tested with concentrations of gaseous toluene in the parts-per-million (ppm) range as well as with various mixtures including different concentrations of oxygen, nitrogen, and humidity. The effect of temperature was also explored. ensors were able to detect toluene concentrations in the parts-per-million range in the absence of oxygen. Both sensors were also useful in detecting the concentration of oxygen. The thicker sensor had a greater photoelectric response than the thinner sensor, and was able to detect toluene in the 1–30 ppm concentration range in air at room temperature.