370 · CHEMICAL SENSORS: FUNDAMENTALS. VOLUME 1: GENERAL APPROACHES this problem with greater success. New device concepts and advances in sensor technologies, derived from improved theoretical understanding of both surface processes and mechanisms of the influence of metal oxide structure on response give hope that future solid-state gas sensors will be stable, simple, inexpensive, and reliable devices with high sensitivity, selectivity, and rapid response. 7. ACKNOWLEDGMENTS G. Korotcenkov thanks the Korean BK21 Program for support of his research. REFERENCES Azad A.M. and Hon N.C. (1998) Characterization of BaSnO 3 -based ceramics. Part 1. Synthesis, processing and microstructural development. J. Alloys Compounds 270, 95­106. Barret P. and Dufour L.C. (eds.) (1985) Reactivity of Solids. Elsevier, Amsterdam. Barsan N., Schweizer-Berberich M., and Gopel W. (1999) Fundamental and practical aspects in the design of nano- scaled SnO 2 gas sensors: a status report. Fresenius J. Anal. Chem. 365, 287­304. Benard S., Retailleau L., Gaillard F., Vernoux P., and Giroir-Fendler A. (2005) Supported platinum catalysts for nitrogen oxide sensors. Appl. Catal. B: Environ. 55, 11­21.