An NO.sub.2 sensor comprises a sensing electrode material that includes a compound consisting essentially of one or more elements selected from the group consisting of Mn, Co, and Fe; an element selected from the group consisting of Si and Ti; and oxygen. In an alternate embodiment, the sensing electrode material includes a compound consisting essentially of one or more elements selected from the group consisting of Mn, Co, and Fe; an element selected from the group consisting of Si and Ti; an element selected from the group consisting of Mg, Al, Li, Na, and K; and oxygen. Sensors made with these sensing electrode materials demonstrate good NO.sub.2 sensitivity and reduced sensitivity to cross-interference from NO and NH.sub.3.

The present invention relates to a gas sensor electrode including a conductive particle phase made of Pt or Pt alloy and a ceramic particle phase being mixed and dispersed, wherein a rate of content of the ceramic particle phase is 6.0 to 22.0 mass %, and a void ratio is 2.5 to 10.0%, and a dispersion degree of the conductive particle phase per length of 25 μm on the electrode surface is 0.60 to 0.85 μm, and a dispersion degree of the conductive particle phase in the electrode cross section per length of 100 μm in a direction parallel to the electrode surface is 2.0 to 4.0 μm. This electrode can be produced by firing a metal paste made by dispersing, in a solvent, a conductive particle having a core/shell structure in which a core particle such as Pt is covered with a ceramic shell and ceramic powder. The gas sensor electrode according to the present invention has a high electrode activity.

A method for manufacturing a sensor element for detecting (i) a gas component in a measuring gas or (ii) a temperature of the measuring gas includes: introducing at least one functional element into at least one slip at least once in such a way that a slip layer is applied to the functional element, the functional element including at least one solid electrolyte and at least one functional layer; sintering the slip layer on the functional element; grinding the slip layer at least in the area of the at least one functional layer; impregnating the slip layer; and thermally treating the impregnated slip layer.

Provided is a flat plate-type oxygen sensor element. The flat plate-type oxygen sensor element according to an exemplary embodiment of the present invention includes: a first electrolyte layer having a sensing electrode exposed to a target gas; a second electrolyte layer on which a reference electrode is disposed; and a heating unit having a heating resistor surrounded by an insulating layer and disposed between the sensing electrode and the reference electrode, wherein the heating unit is disposed so that the heating resistor is located at a position ranging from 40 to 60% of a total height from an upper surface of the first electrolyte layer to a lower surface of the second electrolyte layer.

The gas sensor includes a sensor element, a first insulator inside which the sensor element is inserted, a second insulator disposed on a proximal side of the first insulator so as to cover a proximal side of the sensor element, and a contact member held by the second insulator and sandwiching the sensor element. A proximal end portion of the first insulator and a distal end portion of the second insulator abut on each other in an axial direction. Each the proximal end portion and the distal end portion is provided with a positioning structure. The positioning structure is configured to restrict a relative movement between the first and second insulators in a sandwiching direction in which the sensor element is sandwiched by the contact member and in an orthogonal direction perpendicular to the sandwiching direction and in the axial direction.

A gas detection device including a vessel, wherein the vessel contains an aqueous solution, and a sensing element operably coupled to the vessel, wherein the sensing element is not in direct contact with the aqueous solution.

A protector includes an inside protector having an inside peripheral wall and a front end wall in a front end side thereof and a tubular outside protector which surrounds the inside protector. In an outside peripheral wall of the outside protector, a plurality of outside introducing ports through which an external part of the outside protector communicates with a gas separating chamber are formed at equal intervals along a circumferential direction. The outside introducing ports are formed at positions nearer to the front end side than positions where inside introducing ports of the inside protector are formed. The outside introducing ports extend in the circumferential direction of the outside peripheral wall and formed in shapes of lateral holes in which opening lengths in the circumferential direction are larger than opening lengths in the direction perpendicular to the circumferential direction.

A sensor element includes a base part including a plurality of oxygen-ion-conductive solid electrolyte layers stacked; a measurement-object gas flow part for introduction and flow of a measurement-object gas through one end part in a longitudinal direction of the base part; a main pump cell including an inner main pump electrode disposed on an inner surface of the measurement-object gas flow part, and an outer pump electrode; a target-gas-decomposing pump cell including a target-gas-decomposing pump electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; a residual-oxygen-measuring pump cell including a residual-oxygen-measuring electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; and a reference electrode. The target-gas-decomposing pump electrode comprises a metal material that has catalytic activity of decomposing a target gas to be measured.

A CO sensor includes a solid electrolyte substrate, a sensing electrode, and a reference electrode, and outputs electromotive forces in accordance with CO concentrations. The sensing electrode and the reference electrode are provided on the same surface of the solid electrolyte substrate. The sensing electrode contains a metal oxide such as Bi.sub.2O.sub.3 that generates a positive electromotive force response when coming into contact with CO. The reference electrode contains a metal oxide such as CeO.sub.2 that generates a negative electromotive force response when coming into contact with CO.

A gas concentration detection apparatus is provided with a measuring gas chamber, a solid electrolyte body, a pump cell, a sensor cell, a pump cell controller and a sensor cell detection section. The pump cell controller applies an elimination voltage to the pump cell at a start-up point, before a gas concentration is detected. The water in the measuring gas chamber is decomposed and hydrogen is generated by application of the elimination voltage. Oxygen occluded in a sensor electrode of the sensor cell is removed by the hydrogen.