Abstract: A zirconium oxide shell forms a chamber of fixed volume, and a controller monitors voltage across the shell indicative of difference between inside and outside oxygen levels, applying a signal to pump oxygen. Pumping is effected to empty the chamber, to develop an internal reference, for example by comparison to ambient air, for calibration, and thereafter to substantially continuously null the difference, i.e., to track the oxygen level of a sample environment. Integrated pump current yields a measure of the oxygen added to or removed from the chamber. A suitable material for forming the sensor is a mixture of about 91% zirconium oxide and 9% yttrium oxide, which is formed to shape as a paste or slurry and sintered at about 1400° C., and then platinum coated, for example by a CVD process, to form porous electrodes on each surface. The controller may apply a sequence of current pulses, and check the Nernst cell output indicative of &Dgr;P across the wall, until &Dgr;P=0.

Abstract: Disclosed is a gas sensor comprising a main pumping cell for pumping-processing oxygen contained in a measurement gas introduced into a first chamber, an auxiliary pumping cell for pumping-processing oxygen contained in the measurement gas introduced into a second chamber, a measuring pumping cell for pumping-processing oxygen in the measurement gas introduced via a third diffusion rate-determining section, an ammeter for detecting a pumping current generated depending on an amount of oxygen pumping-processed by the measuring pumping cell, a heater for heating at least the main pumping cell, the auxiliary pumping cell, and the measuring pumping cell to a predetermined temperature, an impedance-detecting circuit for detecting an impedance between an inner pumping electrode and an auxiliary pumping electrode, and a heater control circuit for controlling electric power application to the heater on the basis of a value of the impedance detected by the impedance-detecting circuit.

Abstract: An external conductive protection tube has in a front half wall thereof a front opening formed therein with a front open area large enough to leave molten metal running in due course to inflow therethrough inside the protection tube and advance as it moves, substantially passing by a dipped length of a solid electrolyte tube installed in the protection tube, spreading between the tubes, and in a rear half wall thereof a rear opening formed therein with a rear open area large enough to leave the inflowing molten metal advancing as it moves to pass therethrough, flowing outside the protection tube.

Abstract: A process for measuring the oxygen potential in a silicon melt uses an electrochemical potential probe which dips into the melt. The probe voltage is measured using this potential probe which is made of an SiO.sub.2 glass tube in which graphite is in direct contact with SiO.sub.2 glass. The graphite has a wire making contact with it at the graphite upper end. The probe is dipped into the silicon melt only to an extent such that the graphite/wire contact point contained in the SiO.sub.2 glass tube lies above the silicon melt.

Abstract: Disclosed is a gas sensor comprising a first internal space for making communication with the external space via a first diffusion rate-determining section, a first electrochemical pumping cell for controlling the oxygen concentration in the atmosphere in the first internal space to have a predetermined value, a second internal space for making communication with the first internal space via a second diffusion rate-determining section, a second electrochemical pumping cell for finely adjusting the oxygen concentration in the atmosphere in the second internal space to have a predetermined value, a third internal space for making communication with the second internal space via a third diffusion rate-determining section, a third electrochemical pumping cell for pumping out oxygen produced by reduction or decomposition of a component having bound oxygen in the measurement gas in the third internal space, and an ammeter Ip for detecting a pumping current which is allowed to flow in accordance with the pumping ope

Abstract: A sensor cleaning method and a detection apparatus enabling easy and correct measurement for an uninterrupted prolonged time duration of the gas concentration.The method is based on the value of a limiting current generated on applying a dc voltage across a pair of positive and negative electrodes of a sensor in which the electrodes are formed of a porous material and arranged in intimate contact with the surface of a solid electrolyte substrate exhibiting oxygen ion conductivity and in which pores of the negative electrode are used simultaneously as gas diffusion limiting holes for limiting the amount of diffusion of the gas for measurement. If the limiting current characteristics of sensor versus applied voltage are deteriorated, a voltage opposite to that used during measurement is applied for restoring the characteristics to a normal value.

Abstract: Disclosed is an oxide sensor in which O.sub.2 contained in a measurement gas introduced into a first chamber through a first diffusion rate-determining section is removed by the aid of a pumping voltage applied between pumping electrodes, and then the measurement gas is introduced into a second chamber through a second diffusion rate-determining section to remove excessive O.sub.2 by the aid of auxiliary pumping electrodes. A detecting electrode is arranged to satisfy d.gtoreq.t provided that d represents a distance from an end of the auxiliary pumping electrodes on the side of the second diffusion rate-determining section to an end of the detecting electrode on the side of the second diffusion rate-determining section, and t represents a height of the second chamber. A predetermined pumping voltage is applied to the detecting electrode to decompose oxides contained in the measurement gas by the aid of the detecting electrode or a catalyst.

Abstract: A carbon dioxide gas sensor for detecting carbon dioxide gas concentration wherein the carbon dioxide gas detection part consists essentially of a carbonate, a carbonate decomposition catalyst and a semiconductor oxide, particularly preferably BaCO3, CeO.sub.2 and CuO mixed in a specific molar ratio.A process for producing the carbon dioxide detection part of a carbon dioxide gas sensor, wherein the raw-materials in the form of acetic acid salts are uniformly dissolved in a solvent, then dried and ground to produce a ceramic material with a small average particle diameter.

Abstract: A solid electrolyte gas analyzer is equipped with a diagnostic circuit that intermittently measures an impedance of the solid electrolyte measurement cell as an indication that the cell is in need of calibration or replacement. The diagnostic operation is performed on the cell in situ, i.e., while the solid electrolyte cell is exposed to the gas to be measured and heated to a controlled elevated temperature. Preferably the cell impedance is measured at a predetermined frequency by injecting a modulated current through the cell and measuring the resulting voltage drop.

Abstract: The invention pertains to a solid-state chemical sensor with a substrate support. On one side of the support is mounted a heating element with branch circuit connections. On the other side interdigital electrodes are arranged and thereon a carbon dioxide-sensitive material, which comprises CuO and TiO.sub.3, as well as additional metal oxides, in the form of a thick film of approximately 20-200 .mu.m.

Abstract: The invention relates to an electrochemical sensor to determine the concentration of a gas to be quantified, comprising a housing, a measuring electrode comprising a catalystically active material which causes a reaction of the gas to be quantified, a counterelectrode comprising a carbon material, and a solid electrolyte in contact with the measuring electrode and the counterelectrode, wherein the solid electrolyte is prepared by swelling a solid matrix comprising an acrylate polymer with an electrolytic solution comprising at least one acid, and wherein the carbon material in the counterelectrode has a specific surface of at least 40 m.sup.2 /g and comprises reversibly oxidizable or reducible electrochemically active surface compounds.

Abstract: The invention relates to a reference electrode for electrolytic cells having an ion-conducting solid electrolyte, to sensors comprising the reference electrode of the invention and to their use of the reference electrode for analyzing gases.

Abstract: The invention relates to a a reference electrode for electrolytic cells, comprising a combination of (a) titanium dioxide and an alkali-metal or alkaline-earth-metal titanate or (b) tin dioxide and an alkali-metal or alkaline-earth-metal stannate as a homogeneous mixture.

Abstract: An electrochemical sensor is provided on a substrate whereby a precious metal layer is arranged in an inner region under an electrolyte layer that is surrounded by a polyimide structure. A hydrophobic layer is surrounded by an outer polyimide structure and further is located on top of the electrolyte layer and extends laterally beyond the electrolyte layer. A lead for electrical connection of the precious metal layer extends under the hydrophobic layer laterally from the electrolyte layer is sealed from the hydrophobic layer by a protective layer. The protective layer prevents the penetration of analysis fluid into the gap between the hydrophobic layer and the surrounding polyimide structure into the inner region of the sensor. The material of the protective layer is preferably a double layer of PECVD oxide and PECVD nitride.

Abstract: An oxygen concentration sensor having excellent sealing performance between a lead wire and a lead wire insertion hole includes a sensor element disposed insertedly into a housing, protective covers disposed at an end portion of the housing, lead wires inserted into the protective covers, and an elastic insulating member disposed inside the protective covers and having a lead wire insertion hole for inserting the lead wires. The lead wire insertion hole in the elastic insulating member has a rib protruding in the radial direction. The elastic insulating member is caulked and fixed by the protective covers.

Abstract: An apparatus or method of the present invention measures carbon monoxide included in a hydrogen-rich reactant gas with high precision, and also measures a lower alcohol or another organic compound included in the reactant gas. A carbon monoxide sensor (1) includes an electrolyte membrane (10), a pair of electrodes (12,14) arranged across the electrolyte membrane (10) to form a sandwich structure, a pair of holders (20,22) for supporting the sandwich structure as well as pair of metal plates (16,18), and an insulating member 24 for connecting the holders (20,22) with each other. A gas flow conduit (28) is joined with one holder (20), and a gaseous fuel is fed to the electrode (12) via the gas flow conduit (28). The electrode (14) supported by the other holder (22) is exposed to the atmosphere. A resistor (34) is connected to detection terminals (20T,22T) of the holders (20,22), and a potential difference between both terminals of the resistor (34) is measured with a voltmeter (32).

Abstract: An apparatus for measuring a combustible gas component of a subject gas in an external subject gas space, including a first processing zone communicating with the subject gas space, 58), a second processing zone communicating with the first processing zone, and a first and a second pumping cell exposed to the first and second processing zones, respectively, each cell including an oxygen ion conductive solid electrolyte layer and a pair of electrodes one of which is exposed to the first or second processing zone, wherein the first pumping cell pumps oxygen out of the first processing zone to control oxygen partial pressure in the first processing zone at a value at which the combustible gas component cannot be burned, while the second pumping cell pumps oxygen into the second processing zone to thereby burn the combustible gas component in the second processing zone, and the concentration of the combustible gas component is determined based on a current flowing or a voltage between the electrodes of the second

Abstract: An electrochemical oxygen sensor comprises an impermeable substrate and a plurality of conductive layers applied thereto by thick film deposition. At least one conductive layer comprises an electrode and a conductor connected to the electrode. The electrode may have a covering layer of an ion exchange polymer.

Abstract: A sensor having a working electrode, a solid electrolyte and a counter electrode forming an electrolytic cell within a protective casing is provided. The sensor is utilized for monitoring the concentration of a specific constituent within a sample fluid by measuring the electrical potential difference between the electrode exposed to the sample fluid, which is the working electrode, and the counter electrode, which is exposed to a reference fluid. A protective casing shields the electrolytic cell from the sample fluid and access to the working electrode is provided by sample fluid ports provided in the protective casing. To minimize the surface area of the working electrode exposed to the sample fluid, a restricter is placed in the channel defined by the protective casing and the working electrode.

Abstract: The invention relates to a method and a circuit arrangement for actuating a measuring sensor for determining an oxygen concentration in a gas mixture, particularly in exhaust gases of internal combustion engines, wherein a detector voltage corresponding to the oxygen concentration and supplied by a reference probe is transferred into a pump voltage for a measuring probe by a circuit arrangement.It is provided that a curve of the detector voltage (U.sub.D) is used directly for determining the curve of the pump voltage (U.sub.P), with a first input (38) of the circuit arrangement (36) being connected to a first input (46) of an adder (48) at whose second input (50) an add voltage is applied and whose output (54) is connected to the second input (40) of the circuit arrangement (36) via an amplifier (58).

Abstract: The invention relates to a method as well as to an electrochemical sensor for measuring the concentration of at least one predetermined gas in a gas mixture by means of an electrolyte provided with a first and a second surface-mounted electrode, which are exposed to the gas mixture together with the electrode connected to a voltage source, wherein the voltage source causes an electrical current flowing through the electrodes and electrolyte, which is dependent upon the ion concentration and is measured as an indicator of the gas concentration.

Abstract: The invention relates to a method to measure an electro-chemical activity of a non-metallic liquid layer lying on a molten bath by means of a measuring cell with an electro-chemical element which has an active part and with a counter electrode. The invention also relates to a measuring cell to measure an electro-chemical activity. In order to achieve exact measuring results of an electro-chemical activity with the least possible expenditure, the measuring cell is dipped through a non-metallic liquid layer into a molten bath, the active part of the electro-chemical element being surrounded by the non-metallic liquid layer of the material of this layer on insertion, this material being held at the electro-chemical element until after measuring the electro-chemical activity and the measurement being carried out after dipping the electro-chemical element into the molten metal within the molten bath. The electro-chemical element is especially developed to enable that the material to be measured adheres to it.

Abstract: A sensor for O.sub.2 and CO.sub.2 gases. The gas sensor includes a plurality of layers driven by a cyclic voltage to generate a unique plot characteristic of the gas in contact with the sensor. The plurality of layers includes an alumina substrate, a reference electrode source of anions, a lower electrical reference electrode of Pt coupled to the reference source of anions, a solid electrolyte containing tungsten and coupled to the lower reference electrode, a buffer layer for preventing flow of Pt ions into the solid electrolyte and an upper catalytically active Pt electrode coupled to the buffer layer.

Abstract: A CO.sub.2 gas sensor using a solid reference electrode in combination with a lithium ion conductive solid electrolyte which is at dissociative equilibrium with CO.sub.2 gas, characterized in that the solid reference electrode is made of a lithium containing, mixed transition metal oxide conductor which is of the same conduction type as the solid electrolyte. Further, the solid electrolyte comprises a complex carbonate containing LiAlO.sub.2 as an aggregate. Furthermore, a mixed electrode is used for the solid-electrolyte type gas sensor, which is prepared by the steps of: mixing a Au powder or paste with a powder of an oxide excluding Al.sub.2 O.sub.3 ; rendering a resultant mixture to a paste; applying the paste onto a solid electrolyte; and sintering the applied paste.

Abstract: A CO.sub.2 sensor includes a body of solid electrolyte ceramic with alkali ion conductivity, and two electrodes of conductor material being inert with respect to the solid electrolyte ceramic. At least one of the electrodes is at least partially permeable, and the solid electrolyte ceramic is galvanically prepolarized. A measurement circuit configuration includes the CO.sub.2 sensor and a voltage measuring device coupled to the electrodes of the solid electrolyte ceramic body.

Abstract: The lithium ionic conducting glass thin film of the present invention comprises a glass containing 20 to 80 mol % of an Li.sub.2 O component. This glass thin film has a dense structure which shuts off gas and can be used as a solid electrolyte in a carbon dioxide sensor.The thin carbon dioxide sensor of the present invention comprises the above lithium ionic conducting glass thin film as a solid electrolyte. This sensor enables complete elimination of noise attributed to gas permeation by virtue of the lithium ionic conducting glass thin film having a dense structure with the result that the accuracy of carbon dioxide concentration measurement can be enhanced. Further, the lithium ionic conducting glass is formed into a thin film, so that the sensor has a low internal resistance, acts at low operating temperatures and exhibits a high response speed.

Abstract: A cell block for housing a sensor cell within a gas analyzer is mounted on the front panel of the analyzer, holding the sensor within a horizontal plane. The cell block is made of inexpensive and non-permeable material such as aluminum which is brazed and anodized. Entry and exit of sample gas is unique as is sample gas exposure to the sensor. Dead space is minimized and response time is improved. An insulated thermister in the cell block maintains accuracy over a wide range of temperatures. The device is RFI and EMI protected.

Abstract: Amperometric electrochemical sensors for detection of an analyte gas in air are disclosed. The sensors can be used in a gas detector to detect the analyte gas and to compensate for the relative humidity and temperature of the air. In addition, an electrochemical sensor having high surface area electrodes, and an increased sensitivity, is disclosed.

Abstract: A method is provided for measuring the concentration of a sample gas in an oxygen-containing carrier gas by continuously flowing the oxygen-containing carrier gas which also contains the sample gas whose concentration is to be measured, into and through a central, solid electrolyte inner detector tube, having a particular configuration to eliminate back-diffusion of air thereinto, the inner detector tube having an internal electrode, provided with a first, electrically-conductive output lead, in contact with its interior surface, and an external electrode, provided with a second, electrically-conductive output lead, in contact with its external surface. This bathes a first interface comprising the internal electrode and the interior of the inner detector tube with only the continuously flowing oxygen-containing carrier gas, at a predetermined temperature.

Abstract: Disclosed is a multi-functional voltammetric or amperometric sensor useful for sensing components of the exhaust stream of a combustion system. The disclosed sensor (110) includes a solid oxide ion-conductive electrolyte membrane (112) having two sides (114,116). On one side is a working electrode (120), preferably covered by a diffusion barrier (126) exposed to the exhaust stream. On the other side (116), preferably exposed to air, is a counter-electrode (122) and, optionally, an reference electrode (124). Meters are provided to measure a current flex between the working and counter-electrodes.

Abstract: A low cost room temperature electrochemical gas sensor with humidity compensation for sensing CO, alcohol vapors and other toxic analyte gases has a solid protonic conductive membrane with a low bulk ionic resistance. A sensing electrode and a counter electrode, optionally a counter electrode and a reference electrode, which are separated by the membrane, can be made of mixed protonic-electronic conductors, or can be made of a thin electrically conducting film such as platinum. A reservoir of water maintain the solid protonic conductive membrane at constant 100 percent relative humidity to compensate for ambient humidity changes. Embodiments of the inventive sensor also include an electrochemical analyte gas pump to transport the analyte gas away from the counter electrode side of the sensor.

Abstract: Sensors (10, 40) accurately measure the concentration of an oxide compound, such as nitrogen oxide NO.sub.x, in a gas mixture (11) which can include oxygen O.sub.2. The sensors (10, 40) each comprise a chamber (12, 42) adapted to receive the gas mixture (11) as well as first and second electrochemical cells (16, 17) for consuming oxygen and/or the oxide compound in the chamber (12, 42). The first electrochemical cell (16) comprises a first internal electrode (16a) inside the chamber (12, 42), a first external electrode (16b) outside the chamber (12, 42), and a first electrolyte body (14') therebetween. The second electrochemical cell (17) comprises a second internal electrode (17a) inside the chamber (12, 42), a second external electrode (17b) outside the chamber (12, 42), and a second electrolyte body (14") therebetween. The first and second electrolyte bodies (14', 14") are permeable to oxygen ions.

Abstract: An oxygen sensor is provided with a virtual point contact electrode to improve performance, extend operational life and to minimize thermal shock breakage; it is also provided with reduced annular space between the protective sheath and zirconia electrolyte, and minimized communicating openings to the furnace atmosphere, in order to reduce burnoff air flow during probe conditioning.

Abstract: An oxygen measuring probe for use with molten metal baths for the manufacture of glass which probe comprises a probe body (4) comprising an elongate tubular member (6) closed at one end by a separate tip part (8) formed of stabilised zirconia which constitutes a solid electrolyte through which oxygen ions can pass, said tubular member (6) being formed of a heat-resistant material different from said zirconia, a first electrode (16) connected to the inner surface of the zirconia tip part (8), earthing means adapted for connection to earth out of contact with the molten metal and voltage measuring means (24) connected between the first electrode (16) and said earthing means (26).

Abstract: A method and apparatus are disclosed for measuring atmospheric pressure in conjunction with an air-fuel ratio sensor of the type comprising a concentration cell with atmospheric air and exhaust electrodes on opposite sides of a solid-state electrolyte having oxygen ion conductivity. During an atmospheric pressure measuring cycle, oxygen ions are pumped from the atmospheric air electrode to the exhaust electrode, in a quantity which is either predetermined at a fixed value, or is sufficient to bring the cell to an equilibrium state. Atmospheric pressure is then calculated from measured emf of the cell, using an experimentally derived functional relationship. In a second embodiment, ions are pumped until a predetermined change of the concentration cell emf is achieved, and atmospheric pressure is determined based on the amount of time required to achieve such change. The atmospheric pressure measuring mode is operated on a time shared basis with the air-fuel ration detection mode.

Abstract: A low cost room temperature electrochemical gas sensor for sensing CO and other toxic analyte gases has a solid protonic conductive membrane with a low bulk ionic resistance. A sensing electrode and a count counter electrode, which are separated by the membrane, can be made of mixed protonic-electronic conductors. Embodiments of the inventive sensor also include an electrochemical analyte gas pump to transport the analyte gas away from the counter electrode side of the sensor. Analyte gas pumps for the inventive sensor include dual pumping electrodes situated on opposite sides of the membrane, and include a means for applying a DC power across the membrane to the sensing and counter electrodes. Another embodiment of the inventive sensor has first and second solid protonic conductive membranes, one of which has a sensing electrode and a counter electrode separated by the first membrane, and the other of which has dual pumping electrodes situated on opposite sides of the second membrane.

Abstract: Electrochemical sensors and methods for their use are provided for the detection of the pH and/or oxygen concentration in an aqueous medium. The subject sensors comprise a closed-end cylinder shaped fluoride based solid-state electrolyte having an inner and outer surface. In contact with the inner surface of the electrolyte is a solid reference electrode. In a preferred embodiment, the electrolyte is described by the formula La.sub.0.95 X.sub.0.05 F.sub.2.95, wherein X is an alkaline earth metal. In addition to finding use in the detection of the pH or oxygen concentration of a medium where one these factors is known, at least two of the subject sensors may be used in conjunction, where the reference electrode differs between the two sensors, to determine the pH and oxygen concentration of a medium where both of these values are unknown.

Abstract: A control device and associated methodology select from at least two on-line sensors to assure an accurate and reliable feedback input to control the heat treating conditions within a furnace. The device and methodology also serve to provide an "alert" or "early warning" of gradual degradation of sensor performance, before ongoing heat treating operations are adversely affected.

Abstract: The invention is directed to a method of operating an exhaust-gas probe having a pumped reference atmosphere in a relatively closed volume. In this method, the oxygen ion current, which carries the pump current Ip to the reference atmosphere, is temporarily increased under specific conditions. In this way, an adulteration of the reference atmosphere can be more rapidly eliminated. This adulteration can occur because of fuel particles which diffuse in.