Propagation of acoustic waves in metal oxide nanoparticle layers with catalytic metals for selective gas detection

A novel array comprised of six Love-wave sensors based on metal oxide nanoparticles layers (ZnO and TiO2) mixed with different metals (Co and Pt) was developed to detect, discriminate and classify toxic gases. The metal oxide nanoparticles worked as guiding and sensitive layers at the same time for every sensor. The properties of the different layers of nanoparticles change due to that interaction with the gases, and consequently each sensor suffers a different frequency shift. The array has been tested with different concentrations of ammonia, toluene and xylene. Very low concentrations of these samples have been detected and discriminated by principal component analysis, such as 10 ppm of ammonia, 5 ppm of toluene and 10 ppm of xylene. A correct classification of the measurements has been carried out by means of probabilistic neural network.