Planar zeolite-based potentiometric gas sensors

Titelangaben

Hagen, Gunter ; Moos, Ralf:
Planar zeolite-based potentiometric gas sensors.
In: Sensor Letters. Bd. 9 (2011) Heft 1 . - S. 110-113.
ISSN 1546-198X
DOI: https://doi.org/10.1166/sl.2011.1430

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Abstract

Zeolites are promising materials for gas sensing applications. The properties of high inner surface and catalytic activity are supplemented by internal cation mobility. Therefore, these functional materials provide measurable electrical (ion conductive) characteristics. In the present work, zeolites are applied as ion conductors in a planar potentiometric sensor setup. Two separated electrodes are micro-patterned on alumina substrates. One of them comprises a metal-oxide surface, which was applied by depositing a metal thin-film and subsequent oxidation. Both electrodes are connected by a Pt-doped zeolite thick-film cover on top which acts as the ion conductor. The sensing effect occurs at the interface between zeolite and the different electrode surfaces and is measured as an electromotive force (emf). This signal depends strongly on the gas atmosphere. In addition, the zeolite acts as a catalytic filter affecting the sensor's selectivity. This setup offers a wide range of possible sensor configurations. Electrodes with varying surface materials could be covered by different zeolites that may vary in their Pt- or ion content or in the kind of mobile ions. All manufactured sensors were characterized initially with respect to their signal changes towards hydrogen and propane. The sensor configurations that showed promising results were taken into further investigation. A hydrocarbon-sensitive sensor and a highly sensitive and selective hydrogen sensor could be achieved. The planar setup of the investigated devices leads to a fast response kinetics.