Abstract: An exhaust gas sensor element has an electrolyte body, an inner electrode disposed on an inner surface of the electrolyte body, an outer electrode disposed on an outer surface of the electrolyte body, and a ground isolating coating disposed over the outer electrode. The ground isolating coating is typically alumina and extends from an active end of the electrolyte body toward an opposing end of the electrolyte body. The invention also includes a method for constructing a gas sensor element, the steps of which comprise forming an electrolyte body having an inner surface and an outer surface, applying an electrode ink to the inner surface to form an inner electrode and to the outer surface to form an outer electrode, and depositing a combination poison resistant/ground isolating coating, which is typically alumina, over the outer surface such that the combination coating extends from an active end of the electrolyte body toward an opposing end of the electrolyte body.

Abstract: A gas sensor element is provided which is used in a gas sensor such as an oxygen sensor. The gas sensor element includes a solid electrolyte body, a target gas electrode provided on a surface of the solid electrolyte body so as to be exposed to a gas to be measured, and a reference gas electrode provided on a surface of the solid electrolyte body so as to be exposed to a reference gas. Each of the target gas electrode and the reference gas electrode is made up of a plurality of crystal grains defined by grain boundaries. The total length of the grain boundaries in each of the target gas electrode and the reference gas electrode is 1000 &mgr;m or more in a surface area of 1000 &mgr;m2. This ensures a sufficient degree of diffusion of the gasses in the target and reference gas electrodes, thereby providing a rapid response rate to the gas sensor element.

Abstract: A sensor for determining gas components and concentrations in a gas mixture that is particularly suitable for analyzing HC, NOx and CO in exhaust gases of internal combustion engines in the sensor, an outer electrode, that is separated from an MOx electrode by an electrolyte layer, is applied on a substrate. In this context, the outer electrode and the MOx electrode are in communication with the gas mixture to be analyzed. In addition, the outer electrode contains a region that is in contact with a gas-permeable tunnel layer which in turn contains a region that is directly exposed to the gas mixture to be analyzed, so that the gas to be analyzed can be supplied to the outer electrode via the gas-permeable tunnel layer.

Abstract: An exhaust gas sensor element having an electrochemical cell, a protective material in fluid communication with the electrochemical cell, and a reactive inhibitive coating disposed over the protective material. The reactive inhibitive coating prevents the reaction of compounds with acids(e.g., phosphates) in the exhaust gas, which may form a dense glass layer on the outside of the gas sensor. The reactive inhibitive coating is either an alkaline earth oxide ethoxide, and/or carbonate that is deposited on the gas sensor to a thickness so as to preferably provide an excess of either the alkaline earth material.

Abstract: A device and method for measuring combustible-gas concentration and a device and method for measuring hydrocarbon-gas concentration, which exhibit low dependence on oxygen concentration variations as well as low temperature dependence. Paste is applied to the inner surface of a closed-bottom cylindrical solid electrolyte element, thereby forming a layer serving as a reference electrode. Plating with platinum is performed, so as to form a layer serving as a first detection electrode, on the outer surface of the solid electrolyte element only at a portion extending from an end portion of the solid electrolyte element to the vicinity of the interface between a heating resistor and a heating-resistor lead portion, which are formed within a heater element contained in the cylindrical solid electrolyte element. Paste which contains gold powder and 10 parts of indium oxide is applied onto the platinum-plating layer so as to form a layer serving as a second detection electrode, followed by firing.

Abstract: A gas sensor comprising a housing and arranged such that a gas flow resistant member engages the housing and is sealably positioned to restrict the flow of gas into the opening leading to the cavity. Where the sensor is installed into a cell holder of the gas analyzer, the cell holder may include a gas flow resistant member opener to open the gas resistant member after being contained therein. In this way, the amount of gas to which the sensor is exposed during the transition period is substantially reduced. Accordingly, the amount of gas that diffuses into the electrolyte solution that would, otherwise, adversely affect the accurate and precise measurement of low concentrations of gas at the early stages of operation, is greatly diminished. As a result, the recovery time required for the excess gas to diffuse from the electrolyte is substantially reduced.

Abstract: A sensor element containing a porous layer is provided for detecting a physical magnitude of a measured gas, such as for determining the concentration of a gas component of an exhaust gas of an internal combustion engine. The porous layer includes pores of a first pore type whose diameters correspond to at least half the layer thickness of the porous layer.

Abstract: An emission control system is disclosed for determining a concentration of oxygen in a flow of gas which has a sensor. The sensor has a diffusion barrier, an electrolyte material, and a counter-electrode. The counter-electrode is configured to support the diffusion barrier, and the electrolyte material is disposed between the diffusion barrier and the counter electrode. Also disclosed is a method of producing the sensor and emission control system.

Abstract: Disclosed is a method for fabricating biosensors, using hydrophilic polyurethane. Bio-active reagents, including enzymes, antibodies, antigens, cells and receptors, are mixed with hydrophilic polyurethane and the mixture is directly coated over a signal transducer to form a sensing film which serves as a signal detector. The method using hydrophilic polyurethane allows the simplification of the fabrication of biosensors without conducting complicated chemical reactions and washing steps, such as crosslinking. The bio-active reagent entrapped within the hydrophilic polyurethane film can retains its high activity for an extended period of time and the intrinsic potentiometric response of the underlying ion-selective polymeric membrane is not affected by the bio-active reagent immobilized polyurethane film coated on its sensing surface. Therefore, the biosensors are superior in specificity, selectivity, and stability.

Abstract: An electrode system, particularly for installation in an exhaust line, has a holding body made of an insulating material, on which at least one operating electrode is positioned. The holding body has a heating device for facilitating easy cleaning in the installed position.

Abstract: A gas sensing element has a solid electrolytic body, a reference gas side electrode provided on a surface of the solid electrolytic body so as to be exposed to a reference gas, and a measured gas side electrode provided on another surface of the solid electrolytic body so as to be exposed to a measured gas. A crystal face strength ratio of the measured gas side electrode according to X-ray diffraction is 0.7≦{I(200)/I(111)} or 0.6≦{I(220)/I(111)}.

Abstract: A hardened powder ring, being a hardened block of talc powder, is inserted into an annular end space between a housing and a sensing element. A pushing member presses and crashes the hardened powder ring into talc powder, thereby stuffing the talc powder into the annular end space. An inner radius rp and an outer radius Rp of the pushing member have the relationship 0.275 mm≦rp−R&thgr;≦0.375 mm and 0.15 mm≦rh−Rp≦0.25 mm with respect to an outer radius R&thgr; of the sensing element and an inner radius rh of the housing. A press portion of pushing member has an inner curved surface having a curvature radius of 0.3˜0.4 mm and an outer curved surface having a curvature radius of 0.3˜0.5 mm.

Abstract: A sensor is disclosed that comprises an electrolyte disposed between and in intimate contact with a sensing electrode and a reference electrode. A protective coating is disposed on the protective layer adjacent to the sensing electrode. The protective coating comprises a mixture of a metal oxide, a zeolite, and an alumina. A method for making the sensor is also disclosed.

Abstract: The sensor comprises an electrolyte disposed between a sensing electrode and a reference electrode, with a protective layer contacting the sensing electrode. At least one of the sensing electrode and the reference electrode has a porosity of about 15% or greater. The method for manufacturing the sensor comprises employing a slip. The slip is applied to the electrolyte to form the electrodes, and the electrolyte is heated to a temperature of less than about 1,500° C.

Abstract: One embodiment of a method of fabricating a sensor element for an exhaust gas sensing device, comprises disposing an electrolyte in ionic communication with a sensing electrode and a reference electrode to form the sensor element. The sensing electrode comprises an activator comprising silica and an oxide of an element. The element is selected from the group consisting of alkaline earth elements, rare earth elements, and combinations comprising at least one of the foregoing elements.

Abstract: An amperometric electrochemical gas sensor includes a permanent electrical resistance means disposed between two electrodes, one of which is the working electrode, the electrical resistance means having an electrical resistance of between about 10&OHgr; and 200 k&OHgr;. This resistance means provides a permanent shorting link between the electrodes, and constantly maintains the sensor in a ready-to-work condition.

Abstract: A detector for an air/fuel ratio sensor, which is comprised of a structure formed by stacking an oxygen reference electrode, a dense zirconia solid electrolyte, a negative electrode, a porous zirconia solid electrolyte, a positive electrode and a porous protection film on one another, is formed over a ceramic substrate having a heater built therein. Thus, a combined air/fuel ratio sensor can be obtained which is operated in a short time (about 5 seconds or less) after power-on so as to comply with emission control applied immediately after startup and provides low power consumption and a high degree of reliability.

Abstract: An amperometric electrochemical gas sensor includes a permanent electrical resistance means disposed between two electrodes, one of which is the working electrode, the electrical resistance means having an electrical resistance of between about 10 &OHgr; and 200 k&OHgr;. This resistance means provides a permanent shorting link between the electrodes, and constantly maintains the sensor in a ready-to-work condition.

Abstract: An emission control system for determining a concentration of oxygen in a flow of gas which has a sensor. The sensor has a diffusion barrier, an electrolyte material, and a counter-electrode. The counter-electrode is configured to support the diffusion barrier, and the electrolyte material is disposed between the diffusion barrier and the counter-electrode.

Abstract: The present invention relates to an electrochemical sensor, which has a sensor element (10), and is used to determine a gas concentration of a gas to be analyzed. The sensor element (10) has a first solid electrolyte layer (30), an electrode (34) that includes an electrode surface (32) and an electrode lead (33), and a second solid electrolyte layer (40); a gas channel (31) being introduced into the first solid electrolyte layer (30) in such a manner, that the electrode (34) is situated in a first, clamped region (50) between the first and the second solid electrolyte layers (30, 40), and in a second, open region (51) between the second solid electrolyte layer (40) and the gas compartment (31). In a transition region (52) between the clamped region (50) and the open region (51), the electrode (34) borders on a layer pattern, which is constructed in such a manner, that the electrode (34) is subjected to a lower pressure during a laminating procedure.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: An exhaust gas sensor element having an electrochemical cell, a protective material in fluid communication with the electrochemical cell, and a reactive inhibitive coating disposed over the protective material. The reactive inhibitive coating prevents the reaction of compounds with acids(e.g., phosphates) in the exhaust gas, which may form a dense glass layer on the outside of the gas sensor. The reactive inhibitive coating is either an alkaline earth oxide ethoxide, and/or carbonate that is deposited on the gas sensor to a thickness so as to preferably provide an excess of either the alkaline earth material.

Abstract: A method for making a sensor is disclosed comprising using a sensing electrode having a first and second side. Using a reference electrode having a first and second side and a second electrical lead in electrical communication with the reference electrode. Disposing an electrolyte between the first side of sensing electrode and the first side of reference electrode. Disposing a first side of a protective layer adjacent to the side of sensing electrode. Mixing a metal oxide, a fugitive material, and a solvent to form a mixture. Applying the mixture to a second side of the protective layer and calcining the sensor to form the protective coating on the protective layer second side.

Abstract: A sensor element has a solid electrolyte body holding a reference gas side electrode and a measurement gas side electrode on surfaces thereof. The measurement gas side electrode is covered with a porous protective layer including a component as a lead getter, which reacts with lead contained in measurement gas. Accordingly, lead is removed from measurement gas by the protective layer not to be attached to the measurement gas side electrode. As a result, the sensor element can be used in measurement gas containing lead, without deteriorating responsibility and output thereof.

Abstract: A gas sensing element includes a solid electrolytic substrate having oxygen ion conductivity, a measured gas side electrode provided on a surface of the solid electrolytic substrate so as to be exposed to a measured gas, and a reference gas side electrode provided on another surface of the solid electrolytic substrate so as to be exposed to a reference gas. The measured gas side electrode is covered by a porous electrode protecting layer. A limit current density of the electrode protecting layer is in a range from 0.04 mA/mm2 to 0.15 mA/mm2 on a unit area of the reference gas side electrode.

Abstract: A gas sensor and a method for its manufacture are described. The gas sensor has a solid electrolyte having at least one measuring electrode and one porous protective coating. The measuring electrode has an electrically conductive base layer and a further layer, the further layer god being deposited in the pores of the porous protective coating adjacent to the base layer via galvanic deposition. In order to deposit the further layer via galvanic deposition, the basic body, which has been fused with the base layer and the protective coating via vitrification, is immersed in a galvanizing bath, the base layer being connected as the cathode.

Abstract: An oxygen sensor element is provided which may be used in an oxygen sensor designed to measure the concentration of oxygen contained in exhaust gasses of an automotive internal combustion engine. The gas sensor element includes a solid electrolyte body, a target gas electrode, a reference gas electrode, and a catalytic layer formed over the target gas electrode. The catalytic layer is made of heat resisting ceramic grains which hold thereon catalytic metal grains whose average grain size is 0.3 to 2.0 &mgr;m, a weight of catalytic metal grains per unit area of the catalytic layer, as defined by projecting the target gas electrode on a plane, is 10 to 200 &mgr;g/cm2. This facilitates the reaction of exhaust gasses such as H2, NOx, and HC with O2 over the target gas electrode, thus resulting in improved accuracy of a sensor output over a wide temperature range.

Abstract: The time profile of the output signal of an NOx measurement transducer arranged downstream of the NOx storage catalyst is used, during and after the regeneration phase, to derive a criterion as to whether the quantity of regeneration agent to be supplied to the NOx storage catalyst in a regeneration phase must be changed in order to achieve an optimum action of the exhaust-gas purification system. The output signal is picked off at the amperometric NOx measurement transducer at two electrodes. The measurement transducer exhibits the two-position behavior necessary for the method.

Abstract: A structural arrangement for NOx sensors including a first selectively oxygen ion-conductive layer and a second gas-permeable, nonconductive layer, the latter having a porous spinel structure or porous platinum. The oxygen ion-conductive layer made from a mixed-conductive ceramic can have an additional layer of a material which is catalytically inactive to NOx.

Abstract: A detecting element is configured such that a second electrode is disposed on one side of a plate-like first electrode with a first solid electrolyte layer positioned therebetween and a third electrode is disposed on the other side of the first electrode with a second solid electrolyte layer positioned therebetween, thereby detecting migration of oxygen ions between the first electrode and the second electrode and migration of oxygen ions between the first electrode and the third electrode. Since the second electrode is disposed on one side of the plate-like first electrode with the first solid electrolyte layer positioned therebetween and the third electrode is disposed on the other side of the first electrode with the second solid electrolyte layer positioned therebetween, both planes of the detecting element functions as detecting planes and, to thus extend the directivity of detection in two directions.

Abstract: A gas sensor is provided for measurement of oxygen and/or the air-to-fuel lambda ratio and hydrocarbons and/or carbon monoxide in gas mixtures. To reliably measure a plurality of gaseous components, the sensor is provided with a reference electrode representing a constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, the measuring electrodes and the reference electrode being mounted directly on the solid electrolyte and having electrical leads for connection and for take-away of electrical measurement signals. The solid electrolyte (1) is constructed with a measurement gas side exposed to the gas mixture and a reference gas side separated from the gas mixture.

Abstract: A gas sensor and a method for its manufacture are described. The gas sensor has a solid electrolyte (11) having at least one measuring electrode (15) and one porous protective coating (16). The measuring electrode (15) has an electrically conductive base layer (25) and a further layer (27), the further layer (27) being deposited in the pores of the porous protective coating (16) adjacent to the base layer (25) via galvanic deposition. In order to deposit the further layer (27) via galvanic deposition, the basic body (10), which has been fused with the base layer (25) and the protective coating (16) via vitrification, is immersed in a galvanizing bath, the base layer (25) being connected as the cathode.

Abstract: A plate-shaped sensor element is proposed, in particular for determining the oxygen level in exhaust gases of internal combustion engines. The sensor element has at least one measuring cell with an oxygen-ion-conducting solid electrolyte and a heating element, the measuring cell and the heating element being connected with an electrical insulation layer. The material of the insulation layer is made of at least one crystalline, non-metallic material and at least one glass-forming material, a glazing filled with the crystalline, non-metallic material being formed when the sensor element is sintered.

Abstract: A gas sensor comprises a first pump cell 6 including first internal and external electrodes 10 and 11 so formed as to face from inside and outside a first flow passage 2, respectively, for pumping oxygen out from, and into, the first flow passage, and a second pump cell 8 including second internal and external electrodes 14 and 15 so formed as to face from inside and outside a second flow passage 4 communicating with the first flow passage through a diffusion resistance, wherein a measurement gas component undergoes reaction inside the second flow passage 4 and a current corresponding to the concentration of the measurement gas component flows between the electrodes 14 and 15 through the oxygen ion conductor. At least a part of the first internal electrode 10 contains a platinum group element and Cu.

Abstract: A method of measuring oxygen and/or the air-to-fuel lambda ratio and hydrocarbons and/or carbon monoxide in gas mixtures using a gas sensor is provided. To reliably measure a plurality of gaseous components, the sensor is provided with a reference electrode representing a constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, the measuring electrodes and the reference electrode being mounted directly on the solid electrolyte and having electrical leads for connection and for take-away of electrical measurement signals. The solid electrolyte is constructed with a measurement gas side exposed to the gas mixture and a reference gas side separated from the gas mixture.

Abstract: A second protective layer is a ceramic porous protective layer comprising coarse particles and fine particles structurally arranged in such a manner that interparticle cavities formed between the coarse particles are filled with the fine particles. At least either of the coarse particles and the fine particles contain at least one selected from the group consisting of &ggr;-Al2O3, &thgr;-Al2O3, &dgr;-Al2O3 and solid solution having the same crystal structure as those of &ggr;-Al2O3, &thgr;-Al2O3, &dgr;-Al2O3.

Abstract: A multilayered air-fuel ratio sensing element comprises a solid electrolytic substrate having oxygen ion conductivity. A measuring gas sensing electrode is provided on one surface of the solid electrolytic substrate so as to be exposed to a measuring gas. A reference gas sensing electrode is provided on another surface of the solid electrolytic substrate so that the reference gas sensing electrode is exposed to a reference gas introduced into a reference gas chamber. The measuring gas sensing electrode is covered by a porous diffusive resistor layer. And, a hollow space is provided between the measuring gas sensing electrode and the porous diffusive resistor layer.

Abstract: An oxygen sensor is constituted by a ceramic separator being placed so that the rear thereof enters the inside of a filter holding part and the front enters the inside of a casing and formed with a plurality of lead insertion holes axially penetrating the ceramic separator and an elastic seal member being fitted elastically into a rear opening of the filter holding part and having seal lead insertion holes for inserting leads for sealing the gap between the outer faces of the leads and the inner face of the filter holding part. The rear end face of the ceramic separator is positioned on the rear side behind a gas introduction hole in the axial direction and a predetermined gap is formed between the elastic seal member and the ceramic separator at least at the lead insertion position.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: A multilayered air-fuel ratio sensor consists of a plurality of substrate layers. At least one heterogeneous boundary layer is interposed between the plurality of substrate layers. The heterogeneous boundary layer has a thickness in a range of 10 to 100 &mgr;m. The heterogeneous boundary layer absorbs thermal shocks or any other stresses acting on the substrate layers and stops the growth of cracks.

Abstract: A coating system and a method for its manufacture are provided. An electrically conductive base coat and a porous overcoat lying over the base coat are arranged on a ceramic substrate. At least one additional deposited layer is arranged on the base coat in such a way that the additional layer is formed in the pores of the porous overcoat adjacent to the base coat. The additional layer is deposited either by currentless or electrolytic deposition. For electrolytic deposition of the additional layer, the ceramic substrate sintered with the base coat and the overcoat is submerged in an electrolytic bath and the base coat is connected as a cathode. The currentless deposition takes place from a solution of the metal to be deposited with the addition of a reducing agent.

Abstract: Disclosed is a gas sensor for measuring a NOx concentration comprising a main pumping cell and a detecting electrode, the main pumping cell including an electrode (an inner pumping electrode and an outer pumping electrode) having no decomposing/reducing ability for NOx or a low decomposing/reducing ability for NOx, to be used so that an oxygen concentration in a first chamber is controlled to have a predetermined value at which NO is not substantially decomposable, and the detecting electrode having a certain decomposing/reducing ability for NOx or a high decomposing/reducing ability for NOx, to be used so that NOx is decomposed to measure the NOx concentration by measuring an amount of oxygen produced during this process, wherein a buffering space is provided between a gas-introducing port and the first chamber. Accordingly, it is possible to avoid any influence of exhaust gas pressure pulsation generated in a measurement gas and improve the measurement accuracy on the detecting electrode.

Abstract: Disclosed is a NOx concentration-measuring apparatus for measuring a NOx concentration by using a main pumping cell including an electrode (inner pumping electrode and outer pumping electrode) having no or low decomposing/reducing ability with respect to NOx to control an oxygen concentration in a measurement gas to have a predetermined value which substantially does not affect measurement of NOx component, and using a detecting electrode having certain or high decomposing/reducing ability with respect to NOx to decompose NOx so that an amount of oxygen produced during this process is measured, wherein the detecting electrode is a cermet electrode composed of an alloy of Pt—Rh and a ceramic component, and Pt and Rh are contained in a weight ratio of Pt:Rh=20:80 to 1:99.

Abstract: A Nernstian-type gas sensor for monitoring changes in a concentration of oxygen present in an environment. One embodiment includes a mass of solid-electrolyte material, and first and second electrodes. The first and second electrodes are each in fluid communication with the environment and are arranged to generate a signal therebetween indicative of a difference between an oxygen concentration at the first electrode and an oxygen concentration at the second electrode. The sensor may be free of a temperature control device.

Abstract: The present invention provides a gas sensor element having properties capable of detecting methane and carbon monoxide selectively with 1 sensor by improving gas selectivity of the semiconductor gas sensor. The present invention relates to a gas sensor element, which has a carbon monoxide sensor layer with an ability to function as a catalyst film that blocks carbon monoxide, which impedes detection of methane at the underlying methane sensor, and has a layer-built structure where the surface of a methane sensor is covered with the carbon monoxide gas sensor which can be obtained by a gas-phase method.

Abstract: It is intended to avoid invasion of oxygen through any route except for an introducing port for a measurement gas so that the amount of oxide or inflammable gas contained in the measurement gas may be measured highly accurately. Insulative layers are provided for respective lead wires at positions corresponding to portions at which the temperature of the oxygen ion-conductive solid electrolyte is increased due to heat generation effected by a heater. Each of the insulative layers is formed to have a pattern in which one end is exposed to a first chamber or a second chamber, and the other end terminates at a position separated by a predetermined distance from a corresponding through-hole. At least the lead wires, which lead to an auxiliary pumping electrode and a detecting electrode, are densified. Preferably, the insulative layers for these lead wires are also densified.

Abstract: A sensor element for an electrochemical sensor, in particular for determining the oxygen content in exhaust gases of an internal combustion engine. The sensor element has at least one measuring electrode exposed to a measuring gas, at least one reference electrode exposed to a reference gas, at least one heating device having one heating conductor and two heating conductor leads, and a reference gas channel. The heating conductor has at least two heating circuit trace segments outside the vertical projection of the reference gas channel, the two heating circuit trace segments being connected by a connecting segment routed over the reference gas channel. The circuit trace cross section of the connecting segment is larger than the cross section of one of the heating circuit trace segments.

Abstract: A solid electrolyte fuel cell has an air electrode, a fuel electrode and a solid electrolyte film disposed between the air electrode and the fuel electrode. The solid electrolyte film is formed of yttria-stabilized zirconia in which alumina is added, the concentration of the supplemented alumina at a surface layer section of the solid electrolyte film being larger than that at a center layer section of the solid electrolyte film.

Abstract: There is disclosed an oxygen sensor disposed before an exhaust gas purifying catalyst of an engine which uses a hydrocarbon containing fuel with a H/C ratio of three or more. An oxygen sensor 1 is provided with a solid electrolytic body 2 which can generate a difference in oxygen concentration with reference gas and measured gas, a reference electrode 3 and a detection electrode 4 formed on inner and outer surfaces of the solid electrolytic body 2, and a porous protective layer 5 for covering the detection electrode 4. The detection electrode 4 is formed only of a metal like Pt which promotes oxidizing reaction of methane to have a thickness of 1 to 2 &mgr;m. In the protective layer 5, only a second protective layer 5b carries Pt catalyst 6 which promotes oxidizing reaction of hydrogen, and the amount of carried catalyst is in the range of 0.5 to 7 mol % relative to the whole of the second protective layer 5b.

Abstract: A sensor serves to determine the concentration of oxidizable components in a gas mixture, in particular for determining saturated and unsaturated hydrocarbons by measuring the voltage between at least one measuring electrode and a reference electrode. The material for the measuring electrode is based on compounds of the eschynite class, including eschynites, euxenites and samarskites with general formula AB2O6, which have the general empirical formula A1-xB2-yB′y (O,OH,F)6±z and may be partially doped or may have occupancy defects.