Gas sensors based on nanoparticle WO/sub 3/ thick films

The gas sensing properties of chemical sensors based on nanoparticle WO/sub 3/ thick films, doped with indium and bismuth, are studied. Commercial WO/sub 3/ nanopowder with spherical diameter up to 33.1 nm was mixed with either InCl/sub 3/ or BiCl/sub 3/. The sensing films of the sensors were prepared using three different concentrations of each doping metal (1.5 wt.%, 3.0 wt.% and 5.0 wt.%, respectively). The performance of the sensors was tested for different concentrations of ammonia, nitrogen dioxide and carbon monoxide diluted in synthetic dry air. The sensors were operated at 250/spl deg/C, 300/spl deg/C and 350/spl deg/C in order to analyze the effect of the temperature on their responses. The score plot of a principal component analysis (PCA) showed a linear separation between the three investigated gases. The response characteristics of the produced sensors are discussed on the basis of the structural properties of screen-printed nanoparticle WO/sub 3/ thick films. The results obtained show the possibility to classify and quantify between different gases with nanoparticle WO/sub 3/-doped gas sensors.