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  21.05.2015 - Nanoparticle sensors for security, environment and health protection

 Giovedì 28 maggio p.v., alle ore 10.00, presso l'aula F7, il Dr. Stefan Luby (Institute of Physics SAS, Bratislava, Slovakia) terrà un seminario dal titolo:
" Nanoparticle sensors for security, environment and health protection"

Abstract:Semiconducting metal oxides belong to the frequently used materials in gas sensing both in environmental protection and in medicine. Amongst the broad variety of well established oxides, like SnO2, TiO2, WO3, ZnO, iron oxide γ-Fe2O3 and cobalt – iron oxide CoFe2O4 attract attention because of complex magnetic and electric properties and high chemical reactivity. Moreover, innovative sensors are built from nanoparticle (NP) arrays. These devices with high surface/volume ratio are more sensitive. Our sensors are appropriate for oxidizing NO2 gas. With γ-Fe2O3 the response R = Iair/Igas is 38 at NO2 concentration Cg = 500 ppb and working temperature Tw = 350oC. This result is comparable with the top published sensitivities. With CO and acetone (studied as a marker of diabetes in the patient’s breath) the sensitivities are lower. With CO R = 2.8 at Cg = 100 ppm and Tw = 350oC, with acetone R = 1.8 at Cg = 5 ppm at Tw = 500oC. High sensitivity of NP sensors to oxidizing gases and lower sensitivity to reducing gases was explained by charge carrier self-exhaustion of NPs by surface traps. For the further progress in the field the mechanism of conductivity of NP arrays is of considerable interest.

Ref. Prof. M. Martino