Patent ID: 6660145
Filing Date: 2003-12-09
Classification: G01N

Abstract:
An oxygen sensor element comprising:an oxygen ion conductive solid electrolyte body; a target gas electrode provided on a surface of said solid electrolyte body so as to be exposed to a gas to be measured; a reference gas electrode provided on a surface of said solid electrolyte body so as to be exposed to a reference gas; an electrode protective layer provided to cover said target gas electrode, said electrode protective layer having a porosity of 6 to 30% and a thickness of 70 to 500 &mgr;m; a catalytic layer provided to cover said electrode protective layer, said catalytic layer being made of heat resisting ceramic grains which hold thereon catalytic metal grains whose average grain size is 0.3 to 2.0 &mgr;m, a weight of catalytic metal grains per unit area of said catalytic layer, as defined by projecting the target gas electrode on a plane, is 10 to 200 &mgr;g/cm2; and a catalytic protective layer provided to cover said catalytic layer; wherein said catalytic protective layer has a porosity of 30 to 60% and a thickness of 20 to 150 &mgr;m.