THE THICK-FILM ROUTE TO SELECTIVE GAS SENSORS

Some new routes to gas selectivity are investigated with the help of thick-film screen-printing technology. Selectivity to phosphine is achieved by the gaseous pretreatment of a thick layer of semiconductive iron oxide. Selectivity to methane uses the differential catalytic activity of palladium and platinum versus the combustion of methane in various thick-film sensors: semiconductor oxides, pellistors and combinations of both devices. Finally, a short proposal is presented for improving solid-electrolyte screen-printed sensors, which in contrast to previous ones are basically selective, but normally have an unreliable sensitivity.