Patent ID: 8834693
Filing Date: 2014-09-16
Classification: G01N

Abstract:
1. A gas sensor element including a solid electrolytic substance having a bottomed cylindrical shape and oxygen ion conductivity, a reference electrode arranged on an inner side surface of the solid electrolytic substance, a measuring electrode arranged on an outer side surface of the solid electrolytic substance, and a protective layer which covers the outer side surface of the solid electrolytic substance together with the measuring electrode and which allows gas to be measured to pass through the protective layer, wherein an end side of the gas sensor element is formed of a leg portion whose profile line is straight on an axial cross section, which is a cross section parallel to an axis of the gas sensor element, and a bottom portion whose profile line is curved, the film thickness of the protective layer of the bottom portion is larger than the film thickness of the protective layer of the leg portion, a porosity of the protective layer of the bottom portion is higher than that of the leg portion, the protective layer is formed of at least two layers, an undermost layer of the protective layer, which contacts the measuring electrode, includes a metallic oxide whose chief ingredient includes at least one of alumina, alumina magnesia spinel, and titania, and the gas sensor element further comprises a catalyst layer which covers an outer surface of the protective layer and is formed of a metallic oxide whose chief ingredient includes at least one of alumina, alumina magnesia spinel, and zirconia.