Apparatus and associated methods relate to a one-piece structure for a solid electrolyte chemical sensor (SECS) having a first surface defining a cavity designed to receive a substrate that retains a solid electrolyte, an internal water impermeable coating on at least a portion of the first surface, a second surface that is substantially coplanar with an adjacent peripheral edge of a top surface of the substrate when the substrate is received in the cavity, and a plurality of electrical contacts disposed on the second surface adapted to electrically couple with the electrodes on the substrate when the substrate is received in the cavity and electrical paths are provided between respective electrical contacts and electrodes. In an illustrative example, the internal water impermeable coating may include a metallic material, such as gold. In various embodiments, the one-piece structure may advantageously prevent water loss from both the sensor substrate and the SECS.

A sensor element includes an element body that contains a measurement-object gas flow section and a heat generation portion. The measurement-object gas flow section includes a main pump chamber, an auxiliary pump chamber, and a measurement chamber. A distance X1 in a left-right direction between a part of a first inner linear portion and a part of a second inner linear portion of the heat generation portion that overlap a main pump chamber projection region is equal to or more than ⅓ of a width Wp of the main pump chamber projection region in the left-right direction. A distance X2 in the left-right direction between a part of the first inner linear portion and a part of the second inner linear portion that overlap an auxiliary pump chamber projection region is equal to or more than 0.4 times the width Wp.

A sensor element for detecting a target gas to be measured in a measurement-object gas includes: an element body including an oxygen-ion-conductive solid electrolyte layer; and a protective layer covering at least a part of a surface of the element body. The protective layer includes a porous material that has a pore inside; and, in the pore in the protective layer, a ratio (Lt/Lf) of a pore length (Lt) in a thickness direction perpendicular to the surface of the element body to a pore length (Lf) in a surface direction perpendicular to the thickness direction is 0.6 to 0.9.

A thermochemical sensor is provided. The thermochemical sensor comprises: a substrate structure comprising a thermoelectric surface having concave portions and convex portions; a base fiber disposed on the thermoelectric surface of the substrate structure; and a catalyst layer that conformally covers the thermoelectric surface of the substrate structure and the base fiber.

A gas sensor element includes a solid electrolyte having oxygen-ion conductivity, a first electrode film located on one side of the solid electrolyte, a second electrode film located on the other side of the solid electrolyte. At least one of the first electrode film and the second electrode film includes noble metal particles, solid electrolyte particles having oxygen-ion conductivity, and pores, and a capacitance in the electrode film is 80 μF or less. A gas sensor includes the gas sensor element.

A gas sensor element includes: a first ceramic structure (100A) having a detection cell (120); a second ceramic structure (100B) having a pump cell (110) disposed apart from the first ceramic structure in a lamination direction; and a third ceramic structure (100C) having a frame-shaped body (200) surrounding a space (150a) formed between the first and second ceramic structures, the frame-shaped body including a gas introduction portion (151) and a peripheral wall portion (141). A gap (150b) connected to the space (150a) is formed between an opposed surface (151b1) and the second ceramic structure. A ceramic buffer layer (300) having a lower shrinkage start temperature than a material for forming the gas introduction portion is formed on the opposed surface so as to overlap a boundary portion X between an edge (150b1) on the external side of the gap and the second ceramic structure when viewed in the lamination direction.

In order to suppress a deterioration in the measurement precision while also reducing the manufacturing cost of a gas sensor element, an aspect of the present invention is directed to a gas sensor element including: a stack formed by stacking a plurality of oxygen ion-conductive solid electrolyte layers, and including an internal space configured to receive a measurement target gas from the outside, a first face adjacent to the internal space, and a second face adjacent to an external space; a first pump electrode provided on the first face; a second pump electrode provided on the second face; a first lead formed on the first face so as to extend from the first pump electrode; and a second lead formed on the second face so as to extend from the second pump electrode and configured to be electrically connected to the first lead. At least one of the first and second leads has a shape with a maximum current density of 3.5 A/mm.sup.2 or less.

Disclosed is a manufacturing method of a gas sensor. The gas sensor has a plate-shaped sensor element with at least one pair of electrode pads, a separator disposed around the sensor element, and at least one pair of opposed metal terminals held in an insertion hole of the separator and electrically connected at contact regions thereof to the respective electrode pads. The manufacturing method includes mounting the metal terminals in the insertion hole of the separator with use of a mounting jig. The mounting jig has a flat portion interposed between the contact regions of the metal terminals during the mounting of the metal terminals in the separator so as to prevent contact and entanglement of the opposed metal terminals.

A gas sensor includes a sensor element, an elastic insulating member, a plurality of lead wires, a plurality of metal terminals, and a ceramic housing. The plurality of lead wires are inserted in the elastic insulating member. The plurality of metal terminals each have a first end electrically connected to the sensor element, and a second end electrically connected to a corresponding one of the plurality of lead wires. The ceramic housing includes a plurality of insertion portions each including a through hole in which a corresponding one of the plurality of metal terminals is inserted, and at least one of the plurality of insertion portions has a different height from other insertion portions.

A gas detection device includes a housing, a top disk, an electrochemical sensor, a gasket, and an electrically resistive material, the top disk, electrochemical sensor, gasket and electrically resistive material are located in the housing and the electrically resistive material is located between the housing and the gasket, between the gasket and the top disk, or dispersed through the gasket.