Korea Institute of Science and Technology

Chong Hak Jung

Hyung Jin Jung

Tae Song Kim

A plate-type NO.sub.x gas sensor having a WO.sub.3 sensing film which are capable of preventing temperature variation of a sensing thin film depending on gas flow to decrease heat loss thereof, whereby extending the life span of batteries of a portable gas sensor. The plate-type NO.sub.x gas sensor includes a Pt thin film electrode formed on a front surface of an alumina substrate, a tungsten oxide thin film for sensing NO.sub.x gas deposited on the front surface of the substrate on which the Pt thin film electrode is formed, a heater formed on a back surface of the alumina substrate for holding a portion of the tungsten oxide thin film for sensing NO.sub.x gas within a predetermined temperature range, a conducting wire for connecting between the Pt thin film electrode and the heater and a sheet made of at least one material selected from a group composed of Al.sub.2 O.sub.3, mullite, codierite, magnesia and zirconia, coated on the back surface of the substrate on which the heater is formed, for burying completely the heater from an exterior atmosphere to protect the heat dissipation. The NO.sub.x gas sensor may be fabricated as a bar type and also have a catalytic layer on the sensing layer to enhance the sensing characteristics of the sensor.

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Seoul, South Korea

Chong Hak Jung