Long-term capability of polymer-coated surface transverse wave sensors for distinguishing vapors of similar hydrocarbons

Arrays with polymer-coated sensors have successfully been introduced for the detection of volatile organic compounds (VOC). The VOCs are typically identified via the signal pattern delivered by the sensor array. Therefore, if the VOCs are to be monitored over a longer period, long-term stability of all polymer layers within the array is required. In this study, an array of eight surface transverse wave resonators coated with different polymers was used for semi-annual measurements within one year. The sensor array was used to distinguish between either two aromatic hydrocarbons, i.e., xylene and toluene, or two aliphatic hydrocarbons, i.e., octane and cyclohexane. The polymer coatings proved to be robust as no significant time-related changes of sensor signals and signal patterns were observed. The polymer-coated sensors enabled differentiation of similar aromatic and similar aliphatic hydrocarbons, respectively, as well as subsequent quantification of the VOCs during the complete one-year study.