Abstract: A gas-detecting element comprising an oxygen-ion-conductive solid electrolyte substrate, a sensing electrode fixed onto said solid electrolyte substrate and active with a detection object gas and oxygen, and a reference electrode fixed onto said solid electrolyte substrate and active with at least oxygen, for detecting potential difference between the sensing electrode and the reference electrode to determine the concentration of the detection object gas, the sensing electrode and/or the reference electrode being covered by an electrode-coating layer made of an oxygen-ion-conductive solid electrolyte, and the electrode-coating layer having a portion bonded to the solid electrolyte substrate directly or via an electrode underlayer made of an oxygen-ion-conductive solid electrolyte.

Abstract: The present invention discloses a NOx sensor for accurately detecting the total concentration of nitrogen oxides in a measured gas without being affected by interference gases. The sensor comprises a gas treatment chamber 5 arranged at the prior stage of the gas detection chamber 3, an inorganic porous member 25 loaded in the gas treatment chamber, and a NOx conversion pumping cell 14, 15 and/or an oxygen supplying pumping cell which supplies oxygen into the gas treatment chamber. When the measured gas is introduced in the gas treatment chamber, the interference gases contained in the measured gas are effectively oxidized by the supplied oxygen under the assistance of the catalytic activity of inorganic porous member. The total amount of the nitrogen oxides is measured in the gas detection chamber while NOx in the measured gas are converted into a single component (NO2 or NO) by the NOx conversion pumping cell after the interference gases are oxidized.

Abstract: A gas-detecting element comprising an oxygen-ion-conductive solid electrolyte substrate, a sensing electrode fixed onto said solid electrolyte substrate and active with a detection object gas and oxygen, and a reference electrode fixed onto said solid electrolyte substrate and active with at least oxygen, for detecting potential difference between the sensing electrode and the reference electrode to determine the concentration of the detection object gas, the sensing electrode and/or the reference electrode being covered by an electrode-coating layer made of an oxygen-ion-conductive solid electrolyte, and the electrode-coating layer having a portion bonded to the solid electrolyte substrate directly or via an electrode underlayer made of an oxygen-ion-conductive solid electrolyte.

Abstract: A gas sensor for measuring concentration of a gas component in a measured gas, including a solid electrolytic substrate and at least two electrodes fixed to the substrate. At least a first electrode of the electrodes is disposed in the environment of the measurement gas, at least one of electrodes is polarized by applying a bias current or bias voltage, and a change in the potential of the polarized electrode is measured to thereby measure the concentration of the target gas.

Abstract: A combined gas sensor of the invention is equipped with a second oxygen sensing electrode 5 active only to oxygen, which is disposed on a solid electrolyte substrate 3a such that it is directly exposed to detection gases. Sensor disorder is detected by measuring an electromotive force (signal output 2) generated between a reference electrode 7 and the second oxygen sensing electrode 5 as an oxygen concentration in an exhaust gas atmosphere, and comparing and judging the detected result with a signal output 1 corresponding to an electromotive force between a first oxygen sensing electrode 4 and the sit reference electrode 7, or with a signal output of an oxygen pump current.

Abstract: A nitrogen oxide gas sensor wherein an alloy electrode of platinum and rhodium or a cermet electrode of platinum, rhodium, and zirconia or of a rhodium alloy and zirconia is used as the gas sensing electrode. The electrode of the sensor is suitable for measuring nitrogen oxide such as NO and NO2 in an exhaust gas.

Abstract: The present invention discloses a NOx sensor for accurately detecting the total concentration of nitrogen oxides in a measured gas without being affected by interference gases. The sensor comprises a gas treatment chamber 5 arranged at the prior stage of the gas detection chamber 3, an inorganic porous member 25 loaded in the gas treatment chamber, and a NOx conversion pumping cell 14,15 and/or an oxygen supplying pumping cell which supplies oxygen into the gas treatment chamber. When the measured gas is introduced in the gas treatment chamber, the interference gases contained in the measured gas are effectively oxidized by the supplied oxygen under the assistance of the catalytic activity of inorganic porous member. The total amount of the nitrogen oxides is measured in the gas detection chamber while NOx in the measured gas are converted into a single component (NO2 or NO) by the NOx conversion pumping cell after the interference gases are oxidized.

Abstract: A nitrogen oxide sensor enabled to enhance the measurement concentration of a total of nitrogen oxides by oxidizing or reducing the nitrogen oxides on the surfaces of electrodes in addition to the control of an oxygen concentration by an oxygen pump. An electrode (3a) in a gas chamber (18) constructing an oxygen pumping portion (3) is made of a material (e.g., Pt-3 wt % Rh) having a function to oxidize a nitrogen oxide gas.

Abstract: A nitrogen oxide sensor includes a solid electrolytic substrate exhibiting oxygen ion conductivity, a noble-metal reference electrode, which is active only to oxygen, formed on one side of the solid electrolytic substrate, and a sensing electrode, which is active to NOx and oxygen, formed on the opposite side of the solid electrolytic substrate. A potential difference across the sensing electrode and the reference electrode is output as a signal indicative of NOx concentration. Nitrogen oxides in a gas to be examined or measured gas are converted to NO2 and to peroxides of nitrogen such as N2O5 and NO3, after which the nitrogen oxides in the gas to be examined or measured gas are sensed by the sensing electrode as the peroxides of nitrogen such as N2O5 and NO3 or as a mixed gas of NO2 and the peroxides of nitrogen.

Abstract: A nitrogen oxide gas sensor wherein an alloy electrode of platinum and rhodium or a cermet electrode of platinum, rhodium, and zirconia or of a rhodium alloy and zirconia is used as the gas sensing electrode. The electrode of the sensor is suitable for measuring nitrogen oxide such as NO and NO2 in an exhaust gas.

Abstract: A nitrogen oxide gas sensor wherein an alloy electrode of platinum and rhodium or a cermet electrode of platinum, rhodium, and zirconia or of a rhodium alloy and zirconia is used as the gas sensing electrode. The electrode of the sensor is suitable for measuring nitrogen oxide such as NO and NO2 in an exhaust gas.

Abstract: The present invention discloses a NOx sensor consisting of at least a pair of electrodes formed in touch with an ion conductive solid electrolyte; wherein the first electrode is composed of oxides of a metal (Cr, Mo or W) selected from 6a Group or a substance containing said oxides and an electric conductive material and the concentration of NOx in the test gas is detected by the change of the electromotive force between the first and second electrodes.

Abstract: A stable sensor designed to detect accurately the total NOx concentration under 100 ppm in terms of the NO gas concentration is made up of a first cell and a second cell with a gas diffusion aperture provided between the two cells. The first cell has a partition wall of a substrate of oxygen ion conductor containing zirconia as the main component and permitting a gas to be detected to enter the zirconia substrate; oxygen pumping electrodes are also formed on the first cell substrate which functions to expel oxygen in an atmosphere of the first cell to the outside and to reduce NO.sub.2 of the NOx gas to be detected to NO gas.

Abstract: The present invention discloses a NO.sub.x sensor consisting at least of a pair of the first and the second electrodes formed in touch with an oxygen conductive solid electrolyte; wherein at least the first elelctrode is composed of oxides of an element selected from 7a Group or 8 Group, especially from Mn, Fe, Co, and Ni or a substance containing said oxides or of hybrid oxides (including the one of oxygen deficiency expressed by ABO.sub.3, AB.sub.2 O.sub.4, A.sub.2 BO.sub.4 and ACBO.sub.4 including 7a Group and 8 Group. A NO.sub.x sensor acording to the present invention has a good sensitivity without being affected by the concentration of CO.sub.2 and detects NO.sub.x concentration in an exhaust gas at a temperature above 600.degree. C.

Abstract: The present invention discloses a NOx sensor consisting at least of a pair of the first and the second electrodes formed in touch with an ion conductive solid electrolyte; wherein at least the first electrode is selected from hybrid oxides having perovskite structure expressed by MSnO.sub.3 (M is at least an element selected from Mg, Ca, Sr, Ba, Mn, Co, Ni, Zn and Cd, hybrid oxides having pseudo-perovskite structure expressed by M.sub.2 SnO.sub.4 (M is at least an element selected from Mg, Ca, Sr, Ba, Mn, Co, Zn and Cd) or a substance containing said hybrid oxides and the second electrode is selected from a noble metal or a electro conductive ceramics which does not have electro conductivity in the atmosphere of NOx and the concentration of NOx in the test gas is detected by the change of the electromotive force between the first and second electrodes.

Abstract: A method and a detector for detecting nitrogen oxide in test gas are provided wherein test gas which contains NOx and interference gases is supplied through an oxygen feeder 4 into a measuring chamber 1a, and the interference gases are oxidized by oxygen or oxygen ion supplied to the measuring chamber 1a through oxygen feeder 4. A total amount of NOx in the test gas is detected based on a level of EMF produced between a first electrode 2 for detecting oxygen and NO2 gas and a second electrode 3 for detecting oxygen.