Plural-cell gas sensor with heater

A plural-cell gas sensor including:

• an oxygen pump cell comprising a first oxygen-ion conductive solid electrolyte ceramic layer and internal and external porous electrode layers sandwiching the first solid electrolyte ceramic layer;
• an oxygen monitor cell comprising a second oxygen-ion conductive solid electrolyte ceramic layer and inner and reference electrode layers sandwiching the second oxygen-ion conductive solid electrolyte ceramic layer;
• an internal space defined between the oxygen pump cell layer and the oxygen monitor cell;
• a gas-diffusion inlet through which a gas under measurement enters the internal space;
• a heater substrate comprising first and second insulating ceramic layers and a heating resistor embedded in the insulating ceramic layers;
• and
• a thermal conductive porous ceramic layer sandwiched by the oxygen pump cell and the heater substrate, the first insulating ceramic layer arranged closer to the thermal conductive porous ceramic layer than the second insulating ceramic layer;
• wherein the thermal conductive porous ceramic layer adjoins the external porous electrode of the oxygen pump cell and the insulating ceramic layer of the heater substrate such that oxygen inside the internal space is pumped out through the first oxygen ion conductive solid electrolyte layer and drained off from the external porous electrode of the pump cell layer via the porous ceramic layer so as to vent to an ambient gas atmosphere outside the gas sensor and such that heat from the heater substrate is directly transferred via the thermal conductive porous ceramic layer to the external electrode of the oxygen pump cell, and
• wherein the thermal conductive porous layer covers a part of the external porous electrode layer, the thermal conductive porous layer is only exposed at a lateral side of the plural-cell gas sensor, and having a longitudinally extended rod-like appearance.