Environmental monitoring field tests using screen-printed thick-film sensors based on semiconducting oxides

SnO2, TiO2, In2O3, LaFeO3, and SmFeO3 thick films have been prepared by scr een-printing technology on alumina substrates with comb-type Au electrodes, starting either from commercial or laboratory-synthesized powders. An arra y of thick-film prototype sensors has been placed beside a conventional sta tion for environmental monitoring. Field tests have been performed by measu ring the change in conductivity of the thick films exposed to real atmosphe re. Their electrical response has been compared with the results of the ana lytical instruments for environmental monitoring, approved by the internati onal standards. The same trend was observed for both systems, with very pro mising results, when nanostructured oxides have been used for the preparati on of the thick films. This allows us to consider as feasible the use of th ese sensors for cheap, innovative stations for air quality control. (C) 200 0 Elsevier Science S.A. All rights reserved.