Abstract: Disclosed is a NOx 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 measurement gas 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 cermet electrode composed of a Pt—Rh alloy and a ceramic component is used as the detecting electrode.

Abstract: A composite gas sensor comprises a pump cell, a NOx sensor cell and an oxygen sensor cell. The NOx sensor cell is connected to a first ammeter and a constant power source to measure the NOx concentration of a sample gas. The pump cell is connected to a second ammeter and a variable power source to measure an air-fuel ratio of the sample gas. The oxygen sensor cell is connected to a voltmeter. A controller adjusts the variable power source to produce a constant value from the voltmeter.

Abstract: A method and arrangement is described for determining oxidizable constituents in a gas mixture by using a solid electrolyte cell with at least one reference electrode and at least one working electrode made of electrically conducting mixed oxides which is sensitive to the oxidizable constituents, with the current between the reference electrode and the working electrode induced by electrochemical oxidation of a gas constituent to be determined being measured.

Abstract: A method and apparatus for detecting a functional condition of an NOx occlusion catalyst using an NOx sensor. In order to compensate for variations in oxygen concentration of the exhaust gas which would otherwise affect the detected NOx concentration downstream of the NOx occlusion catalyst, a relative value is calculated as the difference between the detected NOx concentration and the value of the detected NOx concentration initially after start of operation control of an internal combustion engine at a lean air-fuel ratio. The occlusion capability of the NOx occlusion catalyst is judged to have deteriorated when an increase in the relative value exceeds a predetermined value. On the other hand, the NOx occlusion catalyst is judged to have suffered an anomaly when the rate of increase in the relative value becomes greater than a predetermined allowable value.

Abstract: A sensor for measuring nitrogen oxide (NOx) in a gas by decomposing NOx in the gas and measuring an amount of oxygen generated by the decomposition includes: means for introducing the gas to a first inner space under a first diffusion resistance and connected with an external space, means for controlling an oxygen partial pressure in an atmosphere in the first inner space to be a predetermined low value at which NO is not decomposed substantially by a main pump means, means for introducing a controlled atmosphere of the first inner space into a second inner space which is connected with the first inner space and which is under a second diffusion resistance, and means for converting the atmosphere into an electric signal corresponding to the quantity of oxygen generated by decomposition or reduction of NOx contained in the atmosphere by an electric signal conversion means.

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 method for determining relative amounts of O2 and N2O in gas mixtures by quantitative electrochemical reaction including feeding a gas mixture containing O2 and N2O to a zinc-air cell having electrodes connected to a circuit consisting of a plurality of diodes and resistors, which circuit is set to have an electrochemical working range corresponding to each of the O2 and N2O; and measuring current flowing in the respective working range to determine the relative proportions of O2 and N2O in the gas mixture. An electrochemical cell including a casing capable of containing a gas mixture, including O2 and N2O a zinc-air cell in the casing, and a circuit connected to electrodes of the zinc-air cell, the circuit containing a plurality of diodes, resistors and tap points; means for measuring current to determine the relative proportions of O2 and N2O in the gas mixture.

Abstract: Disclosed is a method for controlling a gas sensor comprising the steps of pumping-processing oxygen contained in a measurement gas introduced from external space into a first chamber by using a main pumping cell so that a partial pressure of oxygen in the first chamber is controlled to have a predetermined value at which a predetermined gas component as a measurement objective is not decomposable; decomposing the predetermined gas component contained in the measurement gas in a second chamber by the aid of a catalytic action and/or electrolysis by using a detecting pumping cell to pumping-process oxygen produced during the decomposition; and measuring the predetermined gas component contained in the measurement gas on the basis of a pumping current which flows during the pumping process; wherein the oxygen to be pumped out by the detecting pumping cell is pumped out toward an inner pumping electrode which is fixed to have a base electric potential (ground electric potential), of the main pumping cell.

Abstract: A gas sensor is disclosed in order to decrease the offset value to a degree in which no trouble occurs in the measurement without causing any reduction of NOx so that the measurement accuracy for NOx is improved. In the gas sensor, NOx contained in a measurement gas introduced into a second chamber is decomposed by means of catalytic action and/or electrolysis to pumping-process oxygen produced by the decomposition so that NOx is measured on the basis of a pumping current flowing through a measuring pumping cell thereby. The gas sensor has the following pattern of a heater. That is, a minute pitch is provided for a pattern at a portion corresponding to the forward end of a sensor element, a coarse pitch is provided for a pattern at a central portion, and a pattern is removed at a portion corresponding to the backward end of the sensor element. Thus, the measuring pumping cell is allowed to have a resistivity of electronic conduction of not less than 1 M&OHgr; after conversion into a resistance value.

Abstract: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region thereof which is capable of forming complexes with nitric oxide, for example, nitrosyl complexes. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, thereby leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. Most preferably, the electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are advantageously conditioned in saline solution at +675 mV for about two hours.

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: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region capable of forming complexes with nitric oxide. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. The electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are pre-conditioned at a potential, or potentials, different than the working potential of the electrode, followed by further conditioning at the working potential. Direct response to nitric oxide has been observed for ruthenium electrodes at or below potentials about +675 mV vs. Ag/AgCl, while ruthenium electrodes paradoxical response to nitric oxide has been observed at potentials above +675 mV vs. Ag/Cl.

Abstract: A method for measurement of nitrogen oxides using a gas sensor. To reliably measure nitrogen oxides, the sensor has a reference electrode representing a constant oxygen partial pressure, at least two electrode pairs, with common a electrode associated with each pair of electrodes, and solid electrolytes arranged between the two electrodes of an electrode pair directly at the electrodes. The solid electrolyte between a first electrode pair is gas-permeable, while the solid electrolyte between a second electrode pair is gastight, whereby the second electrode pair is adapated for potentiometric or amperometric measurement of nitrogen oxides, and the first electrode pair is adapted for application of a current or a voltage to pump oxygen. The second electrode of the second electrode pair is constructed as a reference electrode on the reference gas side of the solid electrolyte of the second electrode pair. The sensor also has electrical leads for connection and for take-away of electric measurement signals.

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: Exhaust gas analyzers are disclosed for analyzing the exhaust gases from a combustion process including a sensor unit mounted for direct contact with the exhaust gases in which the sensor unit includes a number of sensors such as lambda sensors, NOx sensors, oxygen sensors, and residual heat sensors, mounted on a common substrate for detecting specific gases and temperatures in the exhaust gases and generating signals based thereon, the substrate being an oxygen-ion-conductive ceramic material and the sensors elements including conductive patterns applied to the common substrate, and a common analyzer connected to the sensor units for analyzing the signals generated by the sensor elements.

Abstract: A process and apparatus for selective detection of NO in fluid media, particularly exhaust gases of internal-combustion engines. This process comprises the steps of positioning a nitrosonium-conducting solid electrolyte between two porous electrodes, acting upon one of the two electrodes with the NO-containing fluid medium, and measuring a voltage difference between the two electrodes as an indication of the NO-concentration in the NO-containing fluid medium.

Abstract: Apparatus for detecting the NOx concentration includes a first measurement chamber 20 communicating with the gas under measurement via a diffusion rate defining layer 4d and a second measurement chamber 26 communicating with the first measurement chamber 20 via diffusion limiting layers 6d, 22d. A first pump current IP1 is controlled so that an output of a Vs cell 6 will be equal to the reference voltage VCO for controlling the oxygen concentration in the first measurement chamber 20 to a pre-set low value. A constant voltage is applied across the second pump cell 8 for decomposing the NOx component in the second measurement chamber 26 for pumping out oxygen for detecting the NOx concentration from a second pump current IP2. The sensor temperature is detected from the internal resistance of the Vs cell for controlling the current supplied to the heaters 12, 14. If the temperature of the gas under measurement is changed rapidly, the sensor temperature is changed.

Abstract: An NOx sensor capable of accurately determining the concentration of NOx contained in a gas to be analyzed (measurement gas) using a simple circuit. The NOx sensor includes a first measurement space and a second measurement space. The first measurement space communicates with the measurement gas via a first diffusion controlling layer, and the second measurement space communicates with the first measurement space via a second diffusion controlling layer. A first pumping current IP1 is controlled such that an output from a Vs cell is used as a reference voltage VC0 to control the amount of oxygen flowing into the second measurement space at a constant level. A constant voltage is applied to the second pumping cell so as to decompose the NOx component of the measurement gas contained in the second measurement space, and to pump out the resulting oxygen from the second measurement space. Accordingly, the concentration of NOx contained in the measurement gas can be obtained from second pumping current IP2.

Abstract: This is a method and apparatus for accurately determining a NOx concentration of a measurement gas that contains H2O and/or CO2, without being affected by a dissociation of H2O and/or CO2.

Abstract: Using a sole Nox sensor Nox concentration and oxygen concentration are measured accurately. A measurement device for measuring NOx concentration and oxygen concentration comprises an NOx sensor 2 having a first measurement chamber 20 communicating via a diffusion rate regulating layer 4d with the gas under measurement and a second measurement chamber 26 communicating with the first measurement chamber 20 via diffusion rate regulating layers 6d, 22d. A first pump cell 4 and an oxygen concentration measurement Vs cell 6 are formed on the first measurement chamber 20, while a second pump cell 8 is formed on the second measurement chamber 26. Inside of the first measurement chamber 20 is controlled to a constant low oxygen concentration by controlling the first pump current IP1 so that output of Vs cell 6 will equal a reference voltage VC0. By applying a constant voltage across the second pump cell 8 NOx in the second measurement chamber 26 is decomposed to pump out oxygen.

Abstract: A galvanic solid electrolyte sensor for measuring gaseous anhydrides includes a ceramic solid electrolyte that has a material that conducts electrons, a measuring electrode that includes a pure or doped alkaline or alkaline earth salt and a reference electrode spatially separated from the measuring electrode and sealed off from the anhydride measuring gas by a gas-tight enclosure. The reference electrode is made of a metal material that conducts electrons. The gas-tight enclosure is made of a layer of a glass containing zirconium and lead that covers only the material of the reference electrode, with only a marginal area of this layer abutting the solid electrolyte.

Abstract: The invention relates to a galvanic cell comprising a) an oxygen-ion-conducting solid electrolyte, b) a gas-sensitive material which contains at least one salt having the structural formula Mem(XOn)p, where Me is a metal, X stands for C, S or N, and the symbols m, n and p characterize the respective stoichiometric relations, c) a material, interposed between the oxygen-ion-conducting solid electrolyte and the gas-sensitive material, which allows conduction both by cations of the metal Me and by electrons and which seals off a potential-determining area of the solid electrolyte surface from the surroundings, making it impervious to gases therein, and d) two electronically conductive potential taps at surface areas of the oxygen-ion-conducting solid electrolyte.

Abstract: A method and apparatus for identifying an unknown reactive gas in a carrier gas, utilizing a sensor with a diffusion limited inlet. After a signal is established for the carrier gas, a flow of the mixture of carrier gas and reactive gas is passed to the sensor and a steady state signal S is established. Then, the input to and output from the sensor are closed, and the steady state signal decays as a known volume of reactive gas is consumed. The decay curve of the signal is integrated to produce an integrated response .SIGMA., and the ratio S/.SIGMA. is proportional to the diffusion coefficient for the reactive gas. By comparing this ratio to the ratio for a known reactive gas, the identity of the unknown reactive gas can be determined.

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: Disclosed is a gas sensor comprising a main pumping cell for pumping-processing oxygen in a first chamber; an auxiliary pumping cell for pumping-processing oxygen in a second chamber; and a measuring pumping cell for pumping-processing oxygen in a measurement gas introduced through a third diffusion rate-determining section; wherein a NOx component contained in the measurement gas is measured on the basis of a pumping current flowing through the measuring pumping cell. The gas sensor further comprises a heater for heating at least the main pumping cell, the auxiliary pumping cell, and the measuring pumping cell to predetermined temperatures; an impedance-detecting circuit for detecting an impedance between an inner pumping electrode and an auxiliary pumping electrode; and a self-diagnosis unit for comparing an impedance value detected by the impedance-detecting circuit with a prescribed value to decide whether or not any trouble occurs, on the basis of a result of comparison.

Abstract: Disclosed are a gas sensor and a gas concentration controller each comprising a comparative amplifier for comparing a reference voltage with a terminal voltage between a reference electrode and an inner pumping electrode to obtain a difference therebetween, and amplifying the difference with a predetermined gain to make an output. Wiring connection is arranged so that the output voltage from the comparative amplifier is applied, as a pumping voltage to an oxygen pump, between the electrode and an outer pumping electrode. A resistor for detecting a pumping current is inserted and connected between an output terminal of the comparative amplifier and the electrode of the oxygen pump. A short circuit is formed between both ends of the resistor by using a capacitor. One electrode of the capacitor is connected to a non-inverting terminal of a differential amplifier, and the other electrode is connected to an inverting terminal of the differential amplifier.

Abstract: Methods for determining the amount of volatile electrolyte present in an aqueous liquid sample comprise transferring the electrolyte from the aqueous liquid sample to an absorber solution across a gas-permeable membrane which is non-passable to the aqueous liquid sample and measuring the change in electrical conductivity of the absorber solution during the transfer period. The absorber solution contains a solute which enhances the transfer of the electrolyte. Apparatus for conducting such methods include an absorber solution containing a solute which enhances the transfer of the electrolyte.

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: A gas sensor using oxygen-ion-conductive solid electrolyte layers measures a concentration of a constituent gas such as NOx in a gas mixture such as an exhaust gas mixture of an internal combustion engine. The gas sensor includes a pair of oxygen pumping cells and a sensor cell. Before the constituent gas concentration is measured by the sensor cell, oxygen gas contained in the gas mixture has to be purged because the oxygen gas adversely affects the measurement of the constituent gas concentration. Two pumping cells disposed to face a chamber, into which the gas mixture is introduced, pump out the oxygen gas contained in the gas mixture so that the oxygen concentration is reduced substantially zero. Then, the gas mixture is diffused to the sensor cell where the constituent gas concentration is measured without the adverse influence of the oxygen gas. A marginal ion current which is proportional to the constituent gas concentration is measured by the sensor cell with a high accuracy and sensitivity.

Abstract: A gas sensor is provided, having an electrolyte membrane, a sensing electrode, a counter electrode, a diffusion barrier for controlling access of gases to the sensing electrode, and in situ means for removing molecular oxygen from the gases to which the sensing electrode is being exposed.

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 method for measuring nitrogen oxide (NOx) in a gas by decomposing NOx in the gas and measuring an amount of oxygen generated by the decomposition includes: introducing the gas to a first inner space under a first diffusion resistance and connected with an external space, controlling an oxygen partial pressure in an atmosphere in the first inner space to be a predetermined low value at which NO is not decomposed substantially by a main pump means, introducing a controlled atmosphere of the first inner space into a second inner space which is connected with the first inner space and which is under a second diffusion resistance, and converting the atmosphere into an electric signal corresponding to the quantity of oxygen generated by decomposition or reduction of NOx contained in the atmosphere by an electric signal conversion means.

Abstract: A system is constructed such that a voltage between an inner pumping electrode and a reference electrode is measured to determine a difference between a measured voltage and a reference voltage so that a pumping voltage is controlled by using the differential voltage. Specifically, a comparative amplifier is provided for comparing the reference voltage with the terminal voltage between the reference electrode and the inner pumping electrode, and amplifying the difference therebetween with a predetermined gain to make an output. The system is wired and connected such that the output voltage (differential voltage) from the comparative amplifier is applied, as the pumping voltage supplied to an oxygen pump, between the inner pumping electrode and an outer pumping electrode. The inner pumping electrode is grounded. Accordingly, for example, when the oxygen pump is used, it is possible to effectively avoid the oscillation phenomenon in the feedback control system for the control voltage for the oxygen pump.

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: A process for removing NO from exhaust in which NO-containing exhaust is guided to a first electrode on which the NO is anodically oxidized to NO.sup.+, the NO.sup.+ is subsequently transported through an NO.sup.+ -conducting solid electrolyte to a second electrode on which the NO is cathodically reduced.

Abstract: Disclosed is a method for controlling a gas sensor comprising the steps of pumping-processing oxygen contained in a measurement gas introduced from external space into a first chamber by using a main pumping cell so that a partial pressure of oxygen in the first chamber is controlled to have a predetermined value at which a predetermined gas component as a measurement objective is not decomposable; decomposing the predetermined gas component contained in the measurement gas in a second chamber by the aid of a catalytic action and/or electrolysis by using a detecting pumping cell to pumping-process oxygen produced during the decomposition; and measuring the predetermined gas component contained in the measurement gas on the basis of a pumping current which flows during the pumping process; wherein the oxygen to be pumped out by the detecting pumping cell is pumped out toward an inner pumping electrode which is fixed to have a base electric potential (ground electric potential), of the main pumping cell.

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: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region thereof which is capable of forming complexes with nitric oxide, for example, nitrosyl complexes. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, thereby leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. Most preferably, the electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are advantageously conditioned in saline solution at +675 mV for about two hours.

Abstract: Disclosed is a gas sensor comprising a main pumping cell including a solid electrolyte layer contacting with an external space, and an inner pumping electrode and an outer pumping electrode formed on inner and outer surfaces of the solid electrolyte layer, for pumping-processing oxygen contained in a measurement gas introduced from the external space on the basis of a control voltage applied between the electrodes; a feedback control system for adjusting the control voltage to give a predetermined level of a voltage between the inner pumping electrode and a reference electrode disposed at a reference gas-introducing space; and a heater for heating at least the main pumping cell to a predetermined temperature; wherein the outer pumping electrode is connected to a negative side lead wire of the heater.

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: A gas sensor for measuring a quantity of specific component in a measuring gas includes a main pump means which has an electrochemical pump cell. The electrochemical pump cell includes a solid electrolyte partition exposed to external space, an inner pump electrode and an outer pump electrode formed on the inner surface and outer surface of the solid electrolyte partition, respectively. The main pump means treats oxygen contained in the measuring gas introduced from the outer space by pumping processing on the basis of a control voltage applied between the inner pump electrode and the outer pump electrode. An RLC element which has a specific electric characteristic value corresponding to a characteristic value of the electrochemical pump cell is connected in parallel with the electrochemical pump cell.

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: The present invention provides an electrochemical gas sensor for the detection of nitrogen dioxide comprising a housing and a working electrode and a counter electrode disposed within the housing. Each of the working electrode and the counter electrode are fabricated from an electrically conductive carbon. The present sensor also preferably comprises a reference electrode fabricated from an electrically conductive carbon.

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: An electrochemical measuring sensor for selectively determining nitrogen oxides in a gas mixture including oxygen and nitrogen oxides, includes a solid electrolyte layer; a cover layer; and a diffusion channel which is defined between the solid electrolyte layer and the cover layer, and through which the gas mixture diffuses in a diffusion direction. The solid electrolyte layer has provided on a surface thereof a first cathode and a second cathode disposed one after the other in the diffusion direction of the gas mixture within the diffusion channel and exposed to the gas mixture in the order recited, and has provided on an opposite surface thereof at least one anode. The diffusion channel forms a diffusion barrier for the second cathode. The first and second cathodes and the at least one anode are gas permeable and consist of one of a precious metal or a precious metal alloy. The first cathode is provided with a coating which completely covers same, which is impermeable to nitrogen oxides (NO.sub.

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.

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: A gas analyzer includes a gas sensor, a drive section that pumps oxygen in first to third processing zones of the gas sensor, an operating section that operates a pumping current flowing in a third electro-chemical pump cell into a gas value to be measured, a display output section that displays a value operated by the operating section, or outputs the value as an electrical output to the external, and a heater drive section that heats the gas sensor to a predetermined temperature.

Abstract: A method for monitoring the constituents present in conversion coating bath solutions. The method involves using specific ac and dc voltammetry and using platinum or other noble metal working electrodes. First, a selected dc potential is applied to a working electrode which has been subjected to pretreatment and which is present as an in-tank sensor in the bath being analyzed. A constant ac signal is superimposed on the dc potential. The dc potential is then swept over a chosen range at a selected sweep rate. The various constituents in the bath are then monitored by measuring dc current and the ac current at one or more reference phase angles with respect to the constant ac signal between the working electrode and a reference electrode as the dc potential is varied. The resulting dc and ac spectra provide a useful measurement of the make-up of the constituents in the bath solutions.

Abstract: A method of calibrating and using a device for the determination of the concentration of an active gas in a mixture of gases wherein the device incorporates a gas sensor (4) and has gas diffusion barrier means (A) and (B), one of which may be closed by a valve (12). The signal from the sensor is recorded at first and second times after closing the valve, and a value for the concentration of an active gas is calculated from the signals and the time difference.