Nanostructured oxides on porous silicon microhotplates for NH3 sensing

Low power micromachined gas sensors based on suspended micro-hotplates are presented in this work. The sensors were fabricated using Porous Silicon Technology. Two different metal-modified nanostructured sensitive materials were deposited on top of the active area of the micro-hotplates, using the micro-dropping technique: SnO2:Pd and WO3:Cr. For the characterization of both gas sensors, measurements in NH3 ambient took place, in isothermal mode of operation. Improved sensors characteristics were obtained for SnO2:Pd sensors, compared to WO3:Cr, for these operating conditions.