A sensor element includes: an element base made of an oxygen-ion conductive solid electrolyte; an internal space provided inside the element base; an electrochemical pump cell configured to pump oxygen in and out between the internal space and outside; a porous thermal shock resistant layer provided to an outermost peripheral part in a predetermined range at one end part of the element base, at which a gas inlet is provided; and a buffer layer adjacent to the thermal shock resistant layer on a pump surface and a heater surface. A thermal diffusion time in a thickness direction of the thermal shock resistant layer is 0.4 sec to 1.0 sec inclusive, and a total thermal diffusion time in a stacking direction of the thermal shock resistant layer and the buffer layer is 0.2 sec to 1.0 sec inclusive.

A sensor element includes an element base made of an oxygen-ion conductive solid electrolyte, an internal space provided inside the element base, an electrochemical pump cell that pumps oxygen in and out between the internal space and outside, and a porous thermal shock resistant layer provided to an outermost peripheral part in a predetermined range at one end part of the element base, at which a gas inlet is provided. A thermal diffusion time in a thickness direction of the thermal shock resistant layer is 0.4 sec to 1.0 sec inclusive. A thermal diffusion time at a leading end part of the thermal shock resistant layer covering the gas inlet at a farthest leading end position at the one end part is longest, and a thermal diffusion time at a pump surface is longer than a thermal diffusion time at a heater surface.

There is presented an electrochemical sensor (100) for sensing an analyte in an associated volume (106), the sensor comprising a first solid element (126), a second solid element (128) being joined to the first solid element, a chamber (110) being placed at least partially between the first solid element and the second solid element, a working electrode (104) in the chamber (110), a reference electrode (108), and wherein one or more analyte permeable openings (122) connect the chamber (110) with the associated volume (106), and wherein the electrochemical sensor (100) further comprises an analyte permeable membrane (124) in said one or more analyte permeable openings, wherein the one or more analyte permeable openings are placed at least partially between the first solid element and the second solid element.

A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having an inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the gas inlet; and an electrochemical pump cell including an outer electrode, an inner electrode facing the chamber, and a solid electrolyte therebetween, and a porous leading-end protective layer covering a leading end surface and four side surfaces in a predetermined range of the element base on the one end portion, wherein the protective layer has an extension extending into the gas inlet and fixed to an inner wall surface of the ceramic body demarcating the gas inlet, and a gap communicating with the gas inlet is located in the protective layer, with demarcated by a portion of the protective layer continuous with the extension.

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 an element body including an oxygen-ion-conductive solid electrolyte layer, the element body having a longitudinal direction, a measurement electrode disposed in the element body, a reference electrode disposed in the element body so as to come into contact with a reference gas, and a heater configured to heat the solid electrolyte layer. A center of gravity of the reference electrode overlaps the measurement electrode as viewed in a thickness direction of the solid electrolyte layer. A length of each of the reference electrode and the measurement electrode in a front-rear direction is less than or equal to 1.1 mm, the front-rear direction being a direction along the longitudinal direction of the element body. An area of the reference electrode as viewed in the thickness direction is greater than or equal to 1.0 mm.sup.2.

A limiting current-type gas sensor element including a plurality of stacked ceramic layers and configured to output a limiting current value which depends on a concentration of a specific gas in a gas to be measured when a certain voltage is applied. The gas sensor element includes a solid electrolyte member having oxygen ion conductivity; a heater that heats the solid electrolyte member; a measurement electrode and a reference electrode provided on the solid electrolyte member; a chamber facing the measurement electrode and into which the gas to be measured is introduced; a gas inlet located to a tip side of the chamber in a longitudinal direction; and a diffusion resistance part provided in the gas inlet. A heating center of the heater is located further to the tip side than an electrode center of the measurement electrode is.

A sensor element and fabrication method thereof, the sensor element includes: a main pump cell including an inner pump electrode facing a first inner space into which a measurement gas is introduced, an external pump electrode provided on an element surface, and a solid electrolyte therebetween; an auxiliary pump cell including an auxiliary pump electrode provided facing a second inner space, the external pump electrode, and the solid electrolyte therebetween; and a measurement pump cell including a measurement electrode, the external pump electrode, and the solid electrolyte therebetween. The inner pump electrode has a porosity of 10 - 25%, the auxiliary pump electrode has a porosity of 30 - 50%, a thickness ratio of both the electrodes is 1.0 - 4.0, and current flowing to the main pump cell has a current density of 0.05 - 0.5 mA/mm.sup.2 when the measurement gas has an oxygen concentration of 20.5%.

A electrochemical sensor (100) for sensing an analyte in an associated volume (106), the sensor comprising a first solid element (126), a second solid element (128) being joined to the first solid element, a chamber (110) being placed at least partially between the first solid element and the second solid element, a working electrode (104) in the chamber (110) and wherein one or more analyte permeable openings (122) connect the chamber with the associated volume (106) and wherein the electrochemical sensor (100) further comprises an analyte permeable membrane (124) in said one or more analyte permeable openings, and wherein the one or more analyte permeable openings are arranged so that a distance from any point in at least one cross-sectional plane to the nearest point of a wall of said opening is 25 micrometer or less.