Zirconia Sensors for Oxygen Measurement

An SOFC in reality already exists on every automobile it is the oxygen sensor device which sits in the exhaust manifold in order to control the oxygen content of the effluent mixture entering the exhaust catalyst. The composition of the effluent mixture must be controlled to near stoichiometric if the catalyst is to operate at its optimum performance. Yttria-stabilised zirconia (YSZ) is generally used as the electrolyte because this uniquely detects oxygen, and platinum is normally painted on its surface using proprietary inks to provide the electrodes. 

This process was rather like the ceramic capacitor process developed for the electronic ceramics industry. 

There were several benefits of this new device  

Oxygen sensors are now widely used in food storage, in metal processing and in flame controllers, but the main market is automobiles. Zirconia technology for sensors has been very successful in the marketplace, and it has pushed forward the development of solid oxide fuel cell materials. The main difference is that the power output of sensors is low so that partially stabilised zirconia can be used. At higher power, fully stabilised zirconia must be used if the electrolyte is to remain stable for long periods. The supply of this electrolyte material is discussed next. 

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