Metal oxide (MO) gas sensors with the potential to operate at ozone concentration levels bellow the critical value of 0.04 ppm set by recognized bodies such as the OSHA and FDA in the USA have been successfully fabricated at IESL/FORTH over the last few years. They have been integrated into a dedicated test chamber equipped with a PATT module and a UV ozone generator, humidity and an air flow meter suitable for food processing tests. Ozone levels are monitored by a combination of a commercial unit and a homemade metal oxide prototype ozone detector. These MO detectors are based on non-stoichiometric InOx thin films grown by dc sputtering. Recent results have shown that films grown at moderate temperatures (~110°C) from a metallic target and in a 100 % oxygen atmosphere exhibit ozone detection levels bellow 0.02 ppm subject to film nanostructure. AFM analyses have shown the contribution of film surface topography to the achieved sensing levels utilizing conductometric techniques.
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