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 screen-printing technology on alumina substrates with comb-type Au electrodes, starting either from commercial or laboratory-synthesized powders. An array of thick-film prototype sensors has been placed beside a conventional station for environmental monitoring. Field tests have been performed by measuring the change in conductivity of the thick films exposed to real atmosphere. Their electrical response has been compared with the results of the analytical instruments for environmental monitoring, approved by the international standards. The same trend was observed for both systems, with very promising results, when nanostructured oxides have been used for the preparation of the thick films. This allows us to consider as feasible the use of these sensors for cheap, innovative stations for air quality control. (C) 2000 Elsevier Science S.A. All rights reserved.