Sensitivity and Response of Polyvinyl Alcohol/Tin Oxide Nanocomposite Multilayer Thin Film Sensors

Nanocrystalline Tin Oxide (SnO2) is Non-Stoichiometric in Nature with Functional Properties Suitable for gas sensing. In this study, SnO2 nanoparticles were prepared by the sol gel technique, which were then characterised using X-ray diffraction. The nanoparticles showed tetragonal structure with an average crystallite size of 18 nm. The stretching and vibration modes of SnO2 were confirmed using Fourier transform infrared spectroscopy. The size of SnO2 nanoparticles was determined using particle size analyser, which was found be 60 +/- 10 nm on average. The surface morphology of the nanoparticles was investigated using scanning electron microscope, which showed irregular-sized agglomerated SnO2 nanostructures. In addition, primary particle size was evaluated using high-resolution transmission electron microscopy, which was found to be 50 nm on average. The polyvinyl alcohol/SnO2 composite thin film was prepared on a glass substrate using spin-coating method. The values of band gap energy and electrical conductance of 13-layer thin film were found to be 2.96 eV and 0.0505 mho, respectively. Sulfur dioxide (SO2) was suitably tailored to verify the sensor response over a concentration range of 10-70 ppm at room temperature. The performance, response, and recovery time of sensors were increased by increasing the layers of the thin film.