Nanostructured thick-film gas sensors for atmospheric pollutant monitoring:: quantitative analysis on field tests

Thick-film gas sensors were fabricated by screen-printing technology starting from different nanostructured semiconducting oxide powders both n-type and p-type; ultrafine and homogeneously sized ceramic powders were prepared using chemical methods such as sol-gel techniques and thermal decomposition of heteronuclear complexes. The temporal evolution of the conductivity changes in the various semiconducting oxide thick films were studied in comparison with the concentrations of CO, NO, NO2 and O-3 in the atmosphere as measured by the analytical equipment. An air quality control experiment in an urban area through some arrays of nanostructured thick-film sensors without an in situ calibration is described. Through the calibration performed directly in the field, one of the monitoring units by means of the conventional equipment, it was possible to evaluate the pollutants' concentration in various points of the city. The good results obtained with this experiment allow us to consider the feasible use of the innovative station to measure the pollution due to the automotive traffic. (C) 2001 Elsevier Science B.V. All rights reserved.