Electronic noses, a different approach to the sensitivity and selectivity issues

Many approaches have been made during the past years to the gas sensing tas k. It may be addressed using one sensor or a set of arranged sensors. Solid state chemical sensing has been systematically used for the development of gas sensor devices, based on semi conducting metal oxides. There are three major issues related to chemical sensing: sensitivity, selectivity and sta bility. Selectivity may be improved by the use of sensor arrays (also refer red as electronic noses), while the use of additives may improve sensitivit y (pure doped materials or porosity control). In this paper we describe our current work about the sensitivity and selectivity issues. A tentative exp lanation of the observed resistance and impedance changes by porosity contr ol is given. (C) 1999 Elsevier Science Limited. All rights reserved.