Abstract: The invention relates to an electrochemical gas sensor having improved response time and sensitivity. The electrochemical gas sensor includes a substrate for providing a surface upon which a film of conductive material may be deposited, a pair of electrodes deposited on the substrate for permitting a measurement of current, and an electrolytic material for providing an electrical connection between the electrodes. The electrochemical gas sensor further includes a passage in the surface for holding or transporting gas received from a gas source, whereby sensing occurs at a three way interface where the gas, electrolytic material, and electrodes come in direct contact with one another.

Abstract: The use of impedance measurements to detect the presence of pathogens attached to antibody-coated beads. In a fluidic device antibodies are immobilized on a surface of a patterned interdigitated electrode. Pathogens in a sample fluid streaming past the electrode attach to the immobilized antibodies, which produces a change in impedance between two adjacent electrodes, which impedance change is measured and used to detect the presence of a pathogen. To amplify the signal, beads coated with antibodies are introduced and the beads would stick to the pathogen causing a greater change in impedance between the two adjacent electrodes.

Abstract: The invention provides a mechanically stable substrate having at least one through-opening, a perforated membrane which is integral or fluid-tightly connected with the substrate and which extends across the through-opening, and at least one semi-permeable layer which is applied in firmly adhering manner to one or both sides of the membrane, at least in the perforated region thereof, in that the semi-permeable layer or semi-permeable layers is/are secured mechanically in the adjacent perforations and/or by chemical-structural and/or physical adhesion and/or adhesive intermediate layers and/or covalent surface bonding to the adjacent surfaces of the membrane, optionally of the substrate, or of a metallic film optionally additionally applied to one or both sides of the membrane. The invention further provides a process for the production of this sensor- and/or separating element and the use thereof.

Abstract: A high throughput screening device for combinatorial chemistry, comprising a membrane electrode assembly, an array of sensor electrodes and one or more common electrodes, wherein a total cross-sectional area of the one or more common electrodes is greater than a sum of the cross-sectional areas of the sensor electrodes is disclosed. This device obtains performance data from each and every array electrode simultaneously and does not require the movement of any electrode during data acquisition. Some application among many possible applications of the device of this invention is in the development and evaluation of catalysts (anode and cathode catalysts) for fuel cells and electrolysis systems.

Abstract: A gas sensor for sensing NOx having electrochemical cells wherein dielectric material surrounds electrolytes except where electrodes are attached. Thereby, the exhaust gas is effectively prevented from contacting the electrolytes of the sensor's electrochemical cells. With the use of this technique, signal cross talk is minimized while enhancing NOx sensing sensitivity. Further, the total number electrodes needed are reduced which allows for more complex sensors structures.

Abstract: The present invention provides an evaluation method and an evaluation system of free halogen concentration which eliminate the necessity of early exchanging or recycling of catalysts, as compared with a conventional method or system. In the present evaluation method of free halogen concentration, a main flow path of a sample liquid for evaluation and a sub-region that communicates with the main flow path are formed, a potential-measuring electrode is installed in the main path, while a reference electrode is installed in the sub-region at a position where free halogen in the sample liquid has been decomposed. Moreover, free halogen in the sample liquid is decomposed by a free-halogen decomposing substance in the sub-region, and the free halogen concentration is evaluated from the electric potential difference between the reference electrode and the potential-measuring electrode.

Abstract: A testing and calibrating device for an evaluation circuit of a linear oxygen probe (S) of an internal combustion engine is disclosed. Said device comprises a probe equivalent circuit (SES) having the same terminals (Vs+, Vs−/Vp−, Vp+ and Rc) as the oxygen probe (S). The probe equivalent circuit can largely emulate the electrical and chemical behaviors of the oxygen probe (S) and simulate probe faults and, at least during a testing and calibrating process, is connected to the evaluation circuit in place of the oxygen probe (S) or is connected parallel to said oxygen probe.

Abstract: A voltametric flow cell for measuring chemical species having improved reliability and accuracy under the high pressure conditions of deep sea water is disclosed. The cell has a three electrode arrangement positioned in a durable polymer for measurement of a wide variety of redox chemicals and ions.

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: A nanostructure based material is capable of accepting and reacting with an alkali metal such as lithium. The material exhibits a reversible capacity ranging from at least approximately 900 mAh/g-1,500 mAh/g. The high capacity of the material makes it attractive for a number of applications, such as a battery electrode material.

Abstract: A gas concentration measuring apparatus is provided which measures the concentration of two kinds of gas components such as O2 and NOx contained in exhaust gasses of an internal combustion engine of automotive vehicles. The apparatus has a gas sensor which includes a first cell responsive to application of a voltage to discharge O2 in the exhaust gasses to the outside and produce an electric current as a function of concentration of the discharged O2 and a second cell responsive to application of a voltage to produce an electric current as a function of concentration of NOx in the exhaust gasses from which the O2 is discharged by the first cell. The apparatus offsets an error component of the electric current produced by the second cell which depends upon O2 contained in the exhaust gasses.

Abstract: Arrangement and method for detecting the end of life of an aqueous bath utilized in semiconductor processing, the bath containing water, an amount of hydrogen peroxide and an amount of a predetermined chemical species, which is either an acid or a base, in accordance with the following steps: adding a predetermined additional amount of the hydrogen peroxide and/or the predetermined chemical species at predetermined time intervals, measuring at least one parameter of the aqueous bath, thereby obtaining a measured parameter value, the at least one parameter being selected from a set of parameters including bath pH and bath conductivity; reading a predicted value of said at least one parameter from a memory storing a curve of predicted values of said at least one parameter as a function of time, said curve depending on said predetermined additional amount of said hydrogen peroxide and/or said predetermined chemical species, and depending on said predetermined time intervals; establishing the end of life of said

Abstract: A nanostructure based material is capable of accepting and reacting with an alkali metal such as lithium. The material exhibits a reversible capacity ranging from at least approximately 900 mAh/g-1,500 mAh/g. The high capacity of the material makes it attractive for a number of applications, such as a battery electrode material.

Abstract: The invention provides a mechanically stable substrate having at least one through-opening, a perforated membrane which is integral or fluid-tightly connected with the substrate and which extends across the through-opening, and at least one semi-permeable layer which is applied in firmly adhering manner to one or both sides of the membrane, at least in the perforated region thereof, in that the semi-permeable layer or semi-permeable layers is/are secured mechanically in the adjacent perforations and/or by chemical-structural and/or physical adhesion and/or adhesive intermediate layers and/or covalent surface bonding to the adjacent surfaces of the membrane, optionally of the substrate, or of a metallic film optionally additionally applied to one or both sides of the membrane. The invention further provides a process for the production of this sensor- and/or separating element and the use thereof.

Abstract: A gas concentration measuring apparatus is provided which measures the concentration of two kinds of gas components such as O2 and NOx contained in exhaust gasses of an internal combustion engine of automotive vehicles. The apparatus has a gas sensor which includes a first cell responsive to application of a voltage to discharge O2 in the exhaust gasses to the outside and produce an electric current as a function of concentration of the discharged O2 and a second cell responsive to application of a voltage to produce an electric current as a function of concentration of NOx in the exhaust gasses from which the O2 is discharged by the first cell. The apparatus offsets an error component of the electric current produced by the second cell which depends upon O2 contained in the exhaust gasses, or which in related operations, depends upon any residual oxygen remaining in the second cell without being discharged by the first cell.

Abstract: In order to prevent a catalyst for an internal combustion engine from decreasing efficiency by deterioration after long time use of the catalyst, the decreased efficiency of the catalyst is determined, and the internal engine is controlled based on results of the determination so as to maintain high efficiency of the catalyst. The catalyst is installed in an exhaust pipe of the engine. Sensors for detecting conditions of exhaust gas both at upstream side and downstream side of the catalyst are provided, respectively. As for the sensor, for example, an oxygen sensor of which output varies stepwise at &lgr;=1, or a sensor of which output varies in proportion to air-fuel ratio can be used. Detected values of the sensors are taken into a control unit, eliminating efficiency and deteriorating degree of the catalyst are estimated by comparison of the detected values, and the engine is controlled so that the eliminating efficiency becomes maximum.

Abstract: An electrolyte comprises a composite of a polymer and a molten salt electrolyte immobilized within the polymer. The electrolyte is stable and ionically conducting at a temperature substantially equal to the melting point of the molten salt electrolyte. In this form, the electrolyte is suitable for use in electrochemical cells, supercapacitors or electrochromic windows and displays.

Abstract: A Lambda probe type gas sensor for use in determining the oxygen content of exhaust gases produced by an internal combustion engine includes a sensor element of the electrochemical, solid electrolyte, metallic oxide semiconductor or Lambda air-fuel ratio variety, which sensor element is arranged in a metallic housing and is contacted by connecting cables that are brought out of the metallic housing. These connecting cables are each surrounded by cable insulation that is made of PTFE (Polytetra-fluoroethylene). The surface of the cable insulation has, at least in certain areas, a gas-permeable section that allows a reference atmosphere to arrive inside the cable insulation and, from there, in the metallic housing. The gas-permeable section, on the other hand, prevents ingress of liquids such as fuel, condensed water, etc., This is achieved, for example, by an additionally applied, PTFE film that is placed over the gas-permeable section.

Abstract: An oxygen electrode having: an electrode substrate; a first electrode and a first lead wire formed on the electrode substrate; an insulating layer formed on the electrode substrate covering the first lead wire; a second electrode and a second lead wire formed on the electrode substrate, and on the insulating layer; a container substrate bonded to the electrode substrate, and having a first recess with an opening over the first and second electrodes for containing electrolyte; and an oxygen permeable film covering the opening. The oxygen electrode may be provided with lead plates and partially molded in an insulating and fixing resin. An oxygen electrode for measuring an oxygen concentration having a novel structure is provided which can be made more compact and/or be used more easily.

Abstract: A method of determining an analyte in the gaseous or vapour phase and in which a bioreceptor or biomimic is retained at an electrode. The bioreceptor or biomimic is preferably retained at a support at the electrode which comprises a solid or gel matrix of an electrolyte, especially organic salt electrolytes. Electrochemical detection of analytes in this way has several advantages over existing methods which rely on solution monitoring. For example gas sensors can be prepared for monitoring an analyte by the occurrence of a reaction with a bioreceptor or biomimic, in addition to monitoring the presence of toxins due to inhibition of the bioreceptor or biomimic reaction. Furthermore, the invention enables gas or vapour analyte monitoring with increased sensitivity and speed and greater stability of the sensors can be achieved. The invention also relates to novel media for carrying out bioelectrochemical reactions.

Abstract: An oxygen concentration detection apparatus for an internal combustion engine is capable of starting feedback control of an air-fuel ratio in the shortest time possible after the engine has been started, thereby preventing the blackening of an oxygen concentration sensor 1, incorrect determination of the air-fuel ratio immediately after start of the current supply to a heating element 20, and damage to the oxygen concentration sensor 1 due to a temperature rise of the heating element 20 when the engine is cold started. A heating state of the heating element 20 of a variable resistance type, which heats the oxygen concentration sensor 1, is detected so that the current supply to an oxygen pumping device 18 is controlled in accordance with the detected state of the heating element 20.

Abstract: A polarographic sensor for determining concentration of certain components including oxygen or combustible fractions, such as hydrocarbons, hydrogen and carbon monoxide, in the exhaust gas of an internal combustion engine, includes a pump cell having an anode, a cathode, and an oxygen ion-conducting solid electrolyte provided between the anode and the cathode, wherein the cathode is provided with a diffusion barrier, wherein the anode is provided with a diffusion barrier, and wherein the concentration of the certain components is determined by measurement of a limiting current through the electrolyte and across one of the diffusion barriers to the corresponding anode or cathode.

Abstract: A solid electrolyte sensor device for determining gas concentrations in measurement gases, with a sensor formed by a solid electrolyte which is arranged between at least two electrodes. The electrodes are permeable to gas and at least one of the electrodes faces the measurement gas. An electrical device is also provided for detecting and processing concentration-dependent sensor output values. For the purpose of permanently preventing disruptive adsorption of measurement gas components on the sensor or on the corresponding sensor electrode, an adjustable oxygen source is arranged in the vicinity of the sensor electrode which faces the measurement gas so that oxygen or oxygen radicals can be introduced into the measurement gas via this oxygen source for the oxidation of the measurement gas.

Abstract: An air fuel ratio detecting device which is improved in accuracy as compared to similar prior art devices comprises a sensor cell for developing an electrical signal in response to the difference between the concentration of oxygen within an exhaust gas and the concentration of oxygen within a reference gas, a controlling means for developing an electrical control signal having a polarity determined from the output of the sensor cell, a pump cell for moving oxygen ions in response to the electrical control signal received from the controlling means, a control current detecting means for detecting control current flow between the controlling means and the pump cell, an air fuel ratio detecting means for detecting an air fuel ratio from the control current flow, a stoichiometric air fuel ratio detecting means for detecting the direction of the control current flow so as to determine the stoichiometric air fuel ratio, a storage means for storing therein a linear air fuel ratio value which is determined from a pr

Abstract: A chemical sensor includes a diode or a transistor fabricated in diamond. A diamond-based diode chemical sensor includes a first diamond layer of first conductivity type and a second diamond or non-diamond layer of second conductivity type. A relatively highly doped region is formed in the first diamond layer, adjacent an electrical contact to reduce the frequency dependance of the sensor's capacitance/voltage characteristic. A diamond-based transistor sensor includes a controlling electrode such as a gate which is configured to allow a chemical external to the transistor to alter the characteristics of the transistor. Relatively highly doped regions are formed adjacent the transistor's controlling electrodes, such as the source and drain. A heater is thermally coupled to the sensor for heating the sensor to a predetermined operating temperature. A temperature monitor is also coupled to the sensor for monitoring the sensor temperature.

Abstract: A sensor element for broad band sensors to determine the .lambda.-value of gas mixtures is suggested. This sensor element can be manufactured in ceramic-sheet and screen-printing technology and is provided in the diffusion gap (7) downstream from a pair of pump electrodes (8,8"), arranged on both sides of the diffusion gasp (7), with a Nernst electrode (9) which functions as an exhaust gas electrode. Due to this arrangement of the Nernst electrode (9), it is possible in a simple manner to effectively protect the pump cell formed by the interior pump electrodes (8,8') from overload and to prevent falsification of the sensor signal.

Abstract: An air/fuel ratio sensor with a sensing element having an electrochemical oxygen pumping cell including a first oxygen ion-conductive solid electrolyte body, and a first and a second electrode formed on the first solid electrolyte body, an electrochemical oxygen sensing cell including a second oxygen ion-conductive solid electrolyte body, and a third and a fourth electrode formed on the second solid electrolyte body, the second and third electrodes being exposed to exhaust gases which are produced as a result of combustion of an air-fuel mixture and which are introduced into the sensing element, under a predetermined diffusion resistance.

Abstract: An automatic chemistry analyzer includes a flow cell mounted so that flow through the cell and tubing connected to the cell is visible from the front of the housing. The electrolytes to the cell are removably plugged into the cell from their rear. The probe aspirating sample fluid into an injection cell is simultaneously washed by diluent and the diluent mixes with the fluid sample. Waste fluid from the flow cell is fed to a basin which then feeds under gravity to a waste drain. A ratio pump is formed by selected syringes which are band driven to deliver accurately prerequisite volumes of reagents to the flow cell. The solution ground to the system is on the inlet line for sample adjacent the entrance to the flow cell of fluid thereby minimizing electronic noise. Only two motive means are necessary, one to effect horizontal and rotational movement of the sample tray, and a second to effect vertical motion of a crane mounted probe operative between sample cups and an injection cell.

Abstract: The invention is directed to a measuring sensor for detecting gaseous components which operates in the diffusion limit current region. The measuring sensor includes a support body and has an electrolyte chamber partitioned by a diffusion membrane from the ambient containing the gaseous components. The measuring electrode of the measuring sensor is improved so that a simpler manipulation for covering the electrolyte chamber with a membrane is possible without endangering the mechanical stability of the membrane. During operation, the detection operation is intended to take place completely at that electrode surface which is in direct electrochemical exchange communication with the electrolyte supply. For this purpose, the coating is configured as an adherence joiner to the support body so that it forms an impermeable adherence region in the lateral direction between coating and support body.

Abstract: An oxygen ion conductive solid-electrolyte plate (1) has first and second opposite surfaces. A plurality of negative electrodes (21b, 22b) and positive electrodes (21a, 22a) are formed on the first and second surfaces of the solid-electrolyte plate (1), respectively, and each of the plurality of negative electrodes (21b, 22b) is opposed to each of the plurality of positive electrodes (21a, 22a). A spacer (5 or 7) is hermetically secured to the first surface of the electrolyte plate (1) and at the same time surrounds each of the plurality of negative electrodes (21b, 22b). A sealing plate (3) is also hermetically secured to the spacer (5 or 7). A plurality of closed spaces (61, 62) are thus defined as spaces surrounded by the solid-electrolyte plate (1), spacer (5 or 7) and sealing plate (3). A plurality of windows (41, 42) are provided in the sealing plate.

Abstract: A sensor element for limiting current sensors for determination of the .lambda.-value of gas mixtures is proposed, which has at least one outer pumping electrode and one inner pumping electrode, on a solid electrolyte in platelet or foil form, conducting O.sup.2- ions, of which the inner pumping electrode is arranged in a diffusion channel for the measuring gas. It consists of a porous three-dimensional precious metal electrode having a supporting structure, the thickness of which electrode corresponds to the height of the diffusion channel. Characteristic of the inner pumping electrode is a greatly improved load-bearing capacity in comparison with electrodes of sheet-like design, whereby the service life of the sensor element is increased. A further advantage of the three-dimensional design of the inner pumping electrode is that it takes on a supporting function during lamination in the production of the sensor element by ceramic foil and screen printing techniques.

Abstract: The amount of ionizable substance within a stream can be continuously monitored through the use of an ionizable substance detector. The substance is ionized at an electrode producing ions and free electrons. The ions are transported across an ion exchange membrane, while the free electrons flow through a power source. The current, produced by the electrons, is proportional to the amount of substance in the stream. Continuous monitoring can be useful in early detection of problems, or system fluctuations.

Abstract: A method and device for measuring energy in fuel gas comprises a solid electrolyte oxygen pump for generating an amount of oxygen in response to current being supplied to the pump. A sample of the gas is mixed with the oxygen from the pump to produce a mixture which is subjected to complete combustion in a catalytic combustor. An oxygen sensor is connected to the catalytic combustor for measuring excess oxygen in the exhaust gas from the combustor. A signal from the oxygen signal is compared to a known and desired amount of excess oxygen in the exhaust gas. If there is too much or too little oxygen inthe exhaust gas, a feedback signal is used to adjust the amount of current being supplied to the oxygen pump until the actual amount of excess oxygen is equal to the selected amount of excess oxygen. The selected amount of excess oxygen is indicative of complete combustion of the sample mixture.

Abstract: A disposable cartridge for use in a clinical sensing arrangement interfaces electrically with a host instrument capable of responding to electrical signals generated by detector devices incorporated in the cartridge upon exposure to calibrant fluids and/or clinical fluids under examination. The cartridge includes a passage linking a reservoir of calibrant fluid to the detector devices and further linking the device to a closed container for fluid which has been conveyed past the devices. A fluid under test can be introducted into the cartridge through the passage wall at a location disposed between the reservoir and the detector devices.

Abstract: For use on automobiles, the invention provides a compact device for measuring the concentration of a nitrogen oxide in a combustion gas such as an exhaust gas of an internal combustion gas. The device has an ion pumping cell using an oxygen ion conductive solid electrolyte to adjust the partial pressure of oxygen in a gas diffusion chamber and a sensor such as an oxygen concentration cell using a solid electrolyte to detect the partial pressure of oxygen in the chamber. The pumping cell or the concentration cell is provided with a catalyst which decomposes the nitrogen oxide in the diffusion chamber only when the partial pressure of coexisting oxygen is sufficiently low.

Abstract: An NOx concentration measuring apparatus employing first and second wide-range air/fuel ratio sensors for measuring an NOx concentration of gases introduced thereto through a first passage. First and second restricted orifices are provided in the first passage upstream of the first and second sensors. A second passage is connected to the first passage between the first and second orifices. A suction pump is connected to the first passage downstream of the first and second sensors for producing a suction vacuum in the first passage and is also connected to the second passage for producing a suction vacuum in the second passage. The first and second orifices are effective to prevent momentary gas pressure fluctuations from affecting the accuracy of measurement of the first and second sensors.

Abstract: A process and apparatus for continuously monitoring of concentrations of gaseous components in gas mixtures, with the exception of O.sub.2. The desired concentration values are obtained simultaneously and separately for the individual gas components, without disruption and with relatively greater accuracy, by a direct path. The concentration of the gaseous component is continuously measured with the aid of at least one electrochemical cell having at least one solid body which contains oxygen-ion-conducting material and a metal-oxide-containing electrode, and generates electrical signals which are a function of the concentration of the component. The measurement signals are electronically and automatically evaluated in a computer which converts them into concentration values. The converted values are compared with reference values of a program which has been programmed into the computer earlier.

Abstract: A limiting current-type oxygen sensor including (a) a pair of oxygen ion-permeable substrates made of a zirconia solid electrolyte; (b) at least one diffusion pore provided in at least one of the substrates, which extends substantially along the thickness of the substrate for causing oxygen diffusion through the diffusion pore to be a rate-determining step; (c) a sealing member for fixing the pair of substrates such that a closed chamber is defined between the substrates; and (d) a pair of porous electrodes provided on both outer and inner surfaces of each electrode.

Abstract: An NOx sensor having an electrochemical cell having a solid electrolyte body and a first and a second electrode, a portion that permits restricted communication of the first electrode with an external measurement gas space, a catalyst disposed adjacent the first electrode for decomposing NOx, a device for applying a current between the first and second electrodes, a current measuring device for detecting a current flowing between the first and second electrodes, an oxygen partial pressure measuring device for detecting an oxygen partial pressure of the atmosphere surrounding the first electrode, and a control device for calculating the concentration of NOx contained in the measurement gas in the external space, based on a first and a second current value.

Abstract: A device for detecting and measuring the concentration of a gas in a mixture of gas such as oxygen in the exhaust gas of an internal combustion engine and circuits for using that measurement to control the air-fuel ratio supplied to the engine. The detecting device has two separate gas residence chamber with different diffusion resistance openings for each chamber and separate pairs of electrodes for each chamber whereby the measurement can be separately made in each chamber. The particular chamber selected for measurement may be done on the basis of whether the air-fuel ratio is lean or rich whereby a substantially linear reading results for all ratios or on the basis of the transition-state or steady-state operating condition of the engine to provide either more rapid or more accurate readings.

Abstract: An air fuel ratio detecting device which is improved in accuracy as compared to similar prior art devices comprises a sensor cell for developing an electrical signal in response to the difference between the concentration of oxygen in the exhaust gas and the concentration of oxygen in a reference gas, a controlling means for developing an electrical control signal having a polarity determined from the output of the sensor cell, a pump cell for moving oxygen ions in response to the electrical control signal received from the controlling means, a control current detecting means for detecting control current flow between the controlling means and the pump cell, an air fuel ratio detecting means for detecting the air fuel ratio from the control current flow, a stoichiometric air fuel ratio detecting means for detecting the direction of the control current flow so as to determine the stoichiometric air fuel ratio, a storage means for storing therein a linear air fuel ratio value which is determined in a predetermi

Abstract: A multi-layer oxygen pump having a one-piece, monolithic ceramic structure affords high oxygen production per unit weight and volume and is thus particularly adapted for use as a portable oxygen supply. The oxygen pump is comprised of a large number of small cells on the order of 1-2 millimeters in diameter which form the walls of the pump and which are comprised of thin, i.e., 25-50 micrometers, ceramic layers of cell components. The cell components include an air electrode, an oxygen electrode, an electrolyte and interconnection materials. The cell walls form the passages for input air and for exhausting the oxygen which is transferred from a relatively dilute gaseous mixture to a higher concentration by applying a DC voltage across the electrodes so as to ionize the oxygen at the air electrode, whereupon the ionized oxygen travels through the electrolyte and is converted to oxygen gas at the oxygen electrode.

Abstract: A moisture (H.sub.2 O) measuring device for high temperature gas deriving the moisture content by taking a difference between measured values of oxygen concentration by an operational process. The one value of the an oxygen concentration is for oxygen content originally included in the measuring gas and the other value of the oxygen concentration is one additionally including oxygen content obtained by electrolysis of the moisture in the measuring gas. The two measured values are controlled by applying voltage for the oxygen pump.

Abstract: An air-fuel ratio sensor in which the temperature dependence as well as the pressure dependence of a detection signal obtained by the air-fuel ratio sensor are suppressed to thereby improve the accuracy in air-fuel ratio by the air-fuel ratio sensor, which is not influenced by deposits in an exhaust gas and which is high in durability. The suppression is achieved by using a gas-diffusion limiting portion having such critical parameters as 10-30% porosity, 1-3 micrometers mean pore size and 200-1000 micrometers thickness. Alternatively the parameters may be 15-25% porosity, 0.1-7 micrometers pore size and 400-800 micrometers thickness.

Abstract: An electrochemical device for detecting a measurement fluid, which includes a planar solid electrolyte body, a first electrode formed on the planar solid electrolyte body and substantially exposed to the measurement fluid, a second electrode formed on the planar solid electrolyte body and substantially isolated from the measurement fluid, a porous layer disposed in direct contact with the second electrode, and a device for applying an electric current so as to flow from the second electrode to the first electrode. The device may further include a third electrode, and a fourth electrode substantially directly exposed to the measurement fluid. In this case, the first and third electrodes are exposed to the measurement fluid through a thin flat space or porous layer having a predetermined diffusion resistance to the measurement fluid, and a current regulating device is connected between the third and fourth electrodes, for controlling an atmosphere adjacent to the first electrode.

Abstract: An oxgen sensor for detecting a measurement gas such as exhaust gases existing in an external space, which has a sensing element having a gas-diffusion space which communicates with the external space. The gas-diffusion space has a predetermined resistance to diffusion of the measurement gas therethrough, and includes a first portion to which the measurement gas diffuses along a first diffusion path, and a second portion to which the measurement gas diffuses through the first portion along a second diffusion path which has a larger length than the first diffusion path.

Abstract: Hydrogen Sulphide is a toxic gas present in many environments. It is necessary for a detector to be highly sensitive and not to respond to other common gases. The sensor is made up of electrodes (5) coated with a thin layer (6) of material comprising the oxides of molybdenum and tungsten and in the presence of hydrogen sulphide gas, changes its resistance. The layer is formed in such a way that a bronze-like ordered lattice is formed, containing molybdenum, tungsten and oxygen ions.

Abstract: An oxygen sensor is provided with an electrolyte tube formed in two parts, one part is an elongated tube and the other part is a sacrificial pellet which thermally insulates the tube from thermal shock which can cause cracks in the tube.

Abstract: An electrochemical device including an electrochemical cell having a first solid electrolyte, and at least one pair of electrodes formed on the first soild electrolyte, and a heating portion having a second solid electrolyte, a first elctrically insulating ceramic layer formed on the second solid electrolyte, and a heater electrically insulated from the second solid electrolyte by the first insulating layer. The device further includes a second electrically insulating ceramic layer interposed between the first and second solid electrolytes, so as to electrically insulate these solid electrolytes from each other, and a protective electrode formed in contact with the second solid electrolyte of heating portion. The protective electrode is electrically connected to at least one of the of electrodes of the electrochemical cell.

Abstract: An oxygen conductive solid electrolyte plate has first and second opposite surfaces, First and second electrodes fixedly extend on the first and second surfaces of the electrolyte plate respectively. A spacing frame hermetically secured to the first surface of the electrolyte plate surrounds the first electrode. The spacing frame has an opening. A sealing plate hermetically secured to the spacing frame defines a chamber in conjunction with the electrolyte plate and the spacing frame. The chamber accommodates the first electrode and opens into an environment only via a window defined by the opening in the spacing frame. The window allows oxygen molecules to flow from the environment into the chamber by diffusion.