Comparison between PPy and PPy/TiO2 as saw sensitive films

We present for the first time, to the best of authors' knowledge, a comparison investigation between the performance of polypyrrole (PPy) and PPy/TiO₂ as surface acoustic wave (SAW) sensitive films employed in situ polymerization and self-assembly method onto ST-X cut quartz substrates for testing TiO₂ dynamically at room temperature. Both sensitive films are characterized with scanning electron microscopy (SEM) and Fourier transform infrared spectroscopic (FT-IR) techniques. The performance of the device is analyzed in terms of frequency shift, which is real time collected by Universal Counter, as a function of the gas concentrations. For the sensitivity of both films, approximately negative frequency shifts of 30 Hz are measured for PPy to 15 ppm of NO₂ but the nearly same amount of positive frequency shifts for PPy/ TiO₂ to lOppm of NO₂. And for the selectivity of both films, about negative 90 Hz and 50 Hz frequency shifts for PPy, but positive 110 Hz and 5 Hz frequency shifts for PPy/TiO₂ are observed towards 100 ppm of NO₂ and 100 ppm of H₂S, respectively.