Cross-linked poly(4-vinylphenol) in thin-film transistors for water analysis

Irregular housing and, consequently, the discharge of sewage in water reservoirs lead to algae proliferation. After their decomposition, they release substances that cause flavor and odor to the water. In this context, this work focused on the development of organic thin film transistors for the analysis of water supplied by the Basic Sanitation Company of the State of São Paulo (SABESP). Electrical devices with fully patterned electrodes were processed over glass substrates. Seeking higher compatibility with flexible substrates, cross-linked poly(4-vinylphenol), a high dielectric constant material, was used. It was demonstrated that only the cross-linked polymer could withstand both electrode photolithography and semiconductor deposition. Subsequently, the performance of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) in gas sensors was investigated. Results obtained in triode regime showed high sensitivity to isoborneol. A current variation greater than 20% in response to 10 ppm of isoborneol represents an important step in the development of a low-cost electronic nose for real-time water quality monitoring.