Abstract: A differential calorimetric gas sensor (10) which includes a sensing element (12) having a catalytic layer (14) disposed on a multi-layered substrate (26). Catalytic layer (14) includes an active catalyst region (14a) which oxidizes total combustibles within an exhaust gas stream and a reference catalyst region (14b) which oxidizes selective combustibles within the exhaust gas stream. An electrochemical oxygen source (18) is disposed on an opposite side of multi-layer substrate (26) from sensing element (12). An oxygen sensor cell (170) may be incorporated into electrochemical oxygen source (18). The multi-layered substrate (26) includes a plurality of overlaying insulating layers in which an intermediate layer (60) and a bottom layer (64) support primary heaters (58, 62), and in which another intermediate layer (52) supports compensation heaters (50a, 50b).

Abstract: A catalytic structure may be in the form of a ceramic support member having disposed on it a catalytic material which is a fired coating (124a-1, 124a-2) of a catalytic ink. The catalytic ink contains a liquid vehicle, at least one metal resinate compound and fine particles of a refractory metal oxide having dispersed thereon a catalytically effective amount of a catalytic metal component such as platinum or palladium or combinations of two or more catalytic metal components. The resulting catalytic structure may be employed as a catalytic gas sensor (24, 124) and further may include at least one conductor member (130, 132) which provides both temperature sensing of the fired catalytic coating (124a-1, 124a-2) to ascertain the degree of reaction taking place at the surface thereof, and heating of the support member to heat the fired catalytic coating to a temperature high enough to promote the catalytic reaction.