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.