Abstract: Herein described is an exhaust gas sensor that is used to detect gas concentration in a “lean only” exhaust stream. The gas sensor comprises a single cell within a dielectric substrate. The cell has an electrolyte with an inner and outer electrode disposed against opposite sides of the electrolyte. A porous protective layer is disposed against the outer electrode. Gases can enter and exit the galvanic cell through the porous protective layer. A voltage is applied across the electrodes, and ions are actively pumped out of the cell. The applied current can be used to determine a specific gas concentration in the exhaust stream.

Abstract: The present invention relates to an improved oxygen sensor and particularly to oxygen sensors used as exhaust sensors in vehicles. The oxygen sensor, which has an improved lean-rich response time and operability at lower temperatures, has been chemically etched and electrically treated, or chemically etched with a non-hydrofluoric acid solution.

Abstract: The invention includes the use of a pre-equilibration zone on an exhaust gas sensor to provide catalytic site to catalyze non-reacted components of the exhaust gas prior to the gas sample reaching the sensor's outer electrode. The pre-equilibration zone has microcomposite which preferably includes a precious metal in a porous carrier such as a ceramic oxide. The invention also includes a method of making an exhaust sensor including a pre-equilibration zone, and a method of sampling an exhaust gas by passing the same through a pre-equilibration zone.