Long-Term Stability of Polymer-Coated Surface Transverse Wave Sensors for the Detection of Organic Solvent Vapors

• Published in: Sensors (Basel, Switzerland) Vol. 17; no. 11; p. 2529
• Main Authors: Stahl, Ullrich, Voigt, Achim, Dirschka, Marian, Barié, Nicole, Richter, Christiane, Waldbaur, Ansgar, Gruhl, Friederike J, Rapp, Bastian E, Rapp, Michael, Länge, Kerstin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 03.11.2017; MDPI
• Subjects: Aliphatic hydrocarbons; Chloroform; electronic nose; gas sensor; Gas sensors; Hydrocarbons; long-term stability; organic solvents; Polymer coatings; Polymers; sensor array; Sensor arrays; Sensors; Solvents; surface acoustic wave; Surface acoustic waves; surface transverse wave; Transverse waves; vapor; volatile organic compounds; Xylene; long-term stability; organic solvents; vapor; volatile organic compounds; surface transverse wave; sensor array; gas sensor; electronic nose; surface acoustic wave
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s17112529

Arrays with polymer-coated acoustic sensors, such as surface acoustic wave (SAW) and surface transverse wave (STW) sensors, have successfully been applied for a variety of gas sensing applications. However, the stability of the sensors' polymer coatings over a longer period of use has hardly been investigated. We used an array of eight STW resonator sensors coated with different polymers. This sensor array was used at semi-annual intervals for a three-year period to detect organic solvent vapors of three different chemical classes: a halogenated hydrocarbon (chloroform), an aliphatic hydrocarbon (octane), and an aromatic hydrocarbon (xylene). The sensor signals were evaluated with regard to absolute signal shifts and normalized signal shifts leading to signal patterns characteristic of the respective solvent vapors. No significant time-related changes of sensor signals or signal patterns were observed, i.e., the polymer coatings kept their performance during the course of the study. Therefore, the polymer-coated STW sensors proved to be robust devices which can be used for detecting organic solvent vapors both qualitatively and quantitatively for several years.