A gas sensor element for detecting a specific gas component in a measured gas, comprising: an element body in the form of a long plate having a gas detection part at an end thereof on a distal end face side in a longitudinal direction; and a porous protective layer covering an outer periphery of the end on said end face side of the element body, wherein in a cross section including two adjacent ones of the end face and side faces connected to the end face, an outer surface of the protective layer facing an element corner where the two faces meet has a shape with a corner part, and a ratio of an assumed diameter of a water droplet contained in the measured gas in a use environment to an effective length of the corner part in the cross section is equal to or larger than 1.5.

A gas sensor element comprising a long plate-like element body and a porous protective layer protecting a surface of the element body, wherein the element body has a gas detection part at an end thereof on one end face side in a longitudinal direction, and the protective layer includes an end face part covering the one end face in laminate, side face parts covering side faces connected to the one end face in laminate, and corner parts where two adjacent ones of the end face part and the side face parts meet. An outer surface of one or more of the end face part and the side face parts has a concave shape that is smoothly continuous with the corner parts and configured such that a layer thickness increases toward the corner parts.

A sensor element includes element main body including side surfaces, a detection unit, connector electrodes disposed on the rear end-side part of the side surfaces, a porous layer that covers at least front end-side part of the side surface, the porous layer having a porosity of 10% or more, and a water-penetration reduction portion. The water-penetration reduction portion is disposed on the side surface so as to divide the porous layer or to be located closer to the rear end than the porous layer. The length L of the water-penetration reduction portion is 0.5 mm or more. The water-penetration reduction portion includes, among a dense layer covering the side surface and having a porosity of less than 10% and a gap region in which the porous layer is absent, at least the dense layer. The water-penetration reduction portion reduces the capillarity of water.

A method for manufacturing a sensor element that includes: a pair of electrodes; a ceramic layer having a hollow space that is to be an air introduction hole; and a first layer and a second layer stacked at both surfaces of the ceramic layer, One of the electrodes is in communication with the hollow space, The method includes: preparing an unsintered ceramic sheet, and a burn-out material sheet having a thickness different from that of the unsintered ceramic sheet, the burn-out material sheet having, in a plane orthogonal to the direction of an axial line O, a cross-sectional area substantially identical to a cross-sectional area of the pre-sintering hollow space; placing the burn-out material sheet in the pre-sintering hollow space; pressing the sheets so as to have an identical thickness; and burning out the burn-out material sheet.

A gas sensor (100) extending in an axial direction AX including: a gas sensor element (120) which detects the concentration of a specific gas in a gas under measurement; a tubular metallic shell (110) having a polygonal tool engagement portion (110B) surrounding the gas sensor element (120); a tubular outer tube (103) which extends rearward from the metallic shell (110), surrounds the gas sensor element (120), and has an opening (103E) at a rear end thereof; a sealing member (191) which seals the opening (103E); and a tubular heat dissipating member (104) which surrounds the outer tube (103) and reduces the amount of heat transferred from the forward end side of the gas sensor (100) through the outer tube (103) to the sealing member (191). The maximum diameter D1 of the heat dissipating member (104) is equal to or less than the opposite side dimension D2 of the tool engagement portion (110B).

A gas sensor includes: a substrate; an insulating layer arranged over the substrate; and a solid electrolyte layer, wherein the substrate is formed with a cavity that penetrates the substrate in a thickness direction of the substrate, wherein the insulating layer has a peripheral portion arranged over the substrate around the cavity, and a membrane portion which is located over the cavity and is connected to the peripheral portion, wherein the membrane portion includes a movable portion, wherein a through-hole, which penetrates the membrane portion around the movable portion in the thickness direction, is formed such that the movable portion is capable of being displaced along the thickness direction, and wherein the solid electrolyte layer is arranged over the movable portion.

A laminated gas sensor element is provided by laminating a plurality of ceramic layers. The gas sensor element includes: a solid electrolyte body having oxygen ion conductivity; a measurement electrode provided on a first principal surface of the solid electrolyte body; a reference electrode provided on a second principal surface of the solid electrolyte body; a chamber facing the measurement electrode and into which a measured gas is introduced; and a heater heating the solid electrolyte body. The chamber comprises at least one projecting corner portion, the at least one projecting corner portion projecting, on a cross section perpendicular to a longitudinal direction of the gas sensor element, in a width direction perpendicular to both of the longitudinal direction and a laminating direction. A tip of the projecting corner portion is disposed on a side closer to the heater than a center of the chamber in the laminating direction is.

There is provided a method of manufacturing a gas sensor that includes: forming an insulating layer on a main surface of a substrate; forming a porous oxide layer on the insulating layer; and forming a porous metal layer on the porous oxide layer, wherein the forming the porous metal layer is performed by depositing a constituent material of the porous metal layer in an inclined direction with respect to a normal line of a main surface.

A sensor element for a gas sensor includes: an element base being a ceramic structure including a sensing part to sense a gas component to be measured; and a leading-end protective layer being a porous layer to surround a predetermined range from a leading end portion on a side of the sensing part of the element base. The leading-end protective layer protrudes at a first end portion thereof opposite to a portion surrounding the element base in a longitudinal direction of the element base. A/B≥1.1 where A is maximum thickness of the leading-end protective layer, and B is thickness of the leading-end protective layer in a base portion that does not protrude.

A resistance-integrated gas sensor is provided, including a substrate, a first metal oxide layer, an insulating layer, a contact metal layer, a contact hole, a second metal oxide layer, and an interdigitated electrode layer. The first metal oxide layer is disposed in the substrate. The insulating layer is disposed on the substrate and the first metal oxide layer. The contact metal layer and the contact hole are disposed in the insulating layer. The second metal oxide layer is disposed on the insulating layer. A portion of the interdigitated electrode layer is disposed on the insulating layer, and another portion is disposed in the second metal oxide layer. The contact metal layer and the contact hole connect the first metal oxide layer and the interdigitated electrode layer.