Abstract: An apparatus for detecting a failure of an exhaust gas sensor disposed in an exhaust manifold is provided. The apparatus comprises a control unit. The control unit compares detection values of the exhaust gas sensor detected under different element temperatures of the exhaust gas sensor. The control unit detects a failure of the exhaust gas sensor based on the comparison result. In one embodiment, the different states include a state in which the element temperature is maintained at higher level and a state in which the element temperature is maintained at lower level. The element temperature can be controlled by a response assignment control scheme. In one embodiment, the detection values are subjected to a filtering process and/or a statistical process using a successive least squares method. The control unit compares the statistically processed detection values to detect a failure of the exhaust gas sensor.

Abstract: A gas concentration measuring apparatus is provided which includes a gas concentration sensor consisting of a pump cell, a sensor cell, and a monitor cell. The pump cell works to determine the concentration of O2. The sensor cell works to decompose an oxygen containing gas such as NOx and provide an output indicative of the concentration of NOx. The apparatus also includes an applying voltage determining circuit which looks up a predetermined voltage-to-current relation to determine a target voltage to be applied to the pump cell as a function of the current produced by the pump cell so as to preclude the pump cell from decomposing the oxygen containing gas component, thereby minimizing an error in determining the concentration of oxygen containing gas as a function of the output of the sensor cell.

Abstract: The invention provides a deterioration detector for an exhaust gas sensor capable of detecting an amount of change with age of an internal resistance and conducting deterioration judgment taking into consideration fluctuation between products and temperature dependency of the internal resistance of the exhaust gas sensor.

Abstract: An apparatus and method for determining the concentration of a medically significant component of a biological fluid comprise providing a cell supporting a chemistry which reacts with the medically significant component. Placement of first and second terminals of the cell in contact with first and second terminals, respectively, of an instrument permits the instrument to assess the reaction. The instrument determines a first response of the cell to a first signal, and determines based upon the first response whether to proceed with the determination of the concentration of the medically significant component of the biological fluid. If the determination is to proceed, the instrument determines the type of sample that has been applied.

Abstract: The invention relates to gas sensors, particularly electrochemical gas sensors. The reliability of such gas sensors has been ascertained by regular tests, which involve exposing a sensor to a gas for test or calibration purposes. However, it has been difficult to provide a known quantity or concentration of gas. Another problem has been that blockage of a gas inlet has rendered the gas sensor unreliable. The invention provides a gas sensor having a self test capability and first and second electrodes, arranged so that test gas arrives at a separate instant at each electrode so as to generate two electric currents, the ratio of which currents provides an indication of the status of at least one electrode.

Abstract: The present invention is to provide a concentration measuring apparatus, a test strip for the concentration measuring apparatus, a biosensor system and a method for forming terminals of the test strip, whereby a component to be measured can be measured by the test strip fit to the target component to be measured. A type judgement electrode is provided separately from a positive electrode and a negative electrode in a measuring apparatus so as to judge the type of a set test strip with the measuring apparatus. Thus only when a test strip matching the measuring apparatus is set, the type judgement electrode is electrically connected to a terminal of the set test strip, enabling the measuring apparatus to measure a component to be measured in a liquid test sample.

Abstract: The invention relates to an amperometric electrochemical cell having a first insulating substrate carrying a first electrode, a second insulting substrate carrying a second electrode, said electrodes being disposed to face each other and spaced apart by less than 500 &mgr;m, and defining a sample reservoir therebetween, and wherein at least one, and preferably both, insulating substrates and the electrode carried thereon include an electromagnetic radiation transmissive portion in registration with said reservoir. The walls of the electrochemical cell may be formed from a thin metallic portion on a transparent substrate. Such cells are useful in providing visual confirmation of the validity of the electrochemical measurement.

Abstract: A chemical detection system performs controlled exposures to diagnose the pneumatic components and chemical sensors prior to measuring a chemical emission. A control module provides the system control and data processing to perform the diagnosis. The control module manipulates an emission sample retrieval system to provide precise exposure during the diagnostic routines. A sensor interface circuit interrogates the chemical sensors and stores the data for analysis. The chemical sensor exhibits predictable changes in response during predetermined exposure scenarios. By utilizing numerous time domain signal processing techniques, both system and sensor level fault conditions are determined.

Abstract: A device for measuring the internal resistance (Ris) of a linear lambda probe (S) of an internal combustion engine is disclosed. The device comprises a voltage amplifier (V6) for amplifying an alternating voltage (VOSZ), which declines to the internal resistance (Ris) and which is induced by an alternating current applied to the first probe terminal Vs+. The inventive device also comprises a synchronous demodulator (V7) for rectifying the amplified alternating voltage (VEIN) and a successive filtering whose amplification factor can be switched over with the frequency of the alternating voltage (VOSZ).

Abstract: This invention relates to an apparatus for and method of making electrical measurements on cells, liposomes or similar small objects suspended in a medium. More particularly the invention relates to an apparatus and method for making electrophysiological measurements on cells.

Abstract: The invention provides a test meter (1) that may be calibrated using a calibration member (16). The calibration member (16) has at least one conductive region (38) of predetermined electrical resistance. The test meter (1) has at least two calibration electrodes (24), processor (34) and dispensing mechanism (22). The dispensing mechanism (22) can be used to dispense a calibration member (16) from the test meter (1). The conductive regions (38) of the calibration member make contact with the electrodes (24) as it is dispensed. The processor (34) receives a signal from the electrodes (24) as the calibration member (16) is dispensed. The processor (34) then processes said signal and generates a calibration signal to calibrate the test meter (1). The invention extends to a method of calibrating a test meter, a cartridge (18) for a test meter and a calibration member (16).

Abstract: The invention relates to a circuit arrangement for measuring the current consumption of a transistor-controlled load, in particular of an electromotor, whereby a load current (IL) is detected by measuring the controlling current (IT2) of an output bipolar transistor (T1). The controlling current (IT2) is detected using the voltage drop across an internal measuring shunt (R1). As the controlling current (IT2) is substantially smaller than the load current, the power losses are negligible in comparison with a measuring shunt that is connected in series to the load. In addition, there is no need for a controlling unit input, to which an external measuring-circuit voltage is applied.

Abstract: According to the present invention, there is provided: a sensor element including an oxygen concentration detection section consisting of solid electrolyte for outputting a detection signal corresponding to an oxygen concentration in a hollow chamber to which an exhaust of an internal combustion engine is introduced and an oxygen pump section for controlling an electric current to be applied to a solid electrolyte wall that divides the hollow chamber from an exhaust side of the engine so that the oxygen concentration in the hollow chamber becomes a predetermined oxygen concentration, to flow oxygen into/out of the hollow chamber; an air-fuel ratio detection circuit for outputting an air-fuel ratio detection value based on the electric current applied to the solid electrolyte wall by the oxygen pump section; and a pump current cut off circuit for cutting off the power supply to the solid electrolyte wall by the oxygen pump section, and a detection value of air-fuel ratio is corrected based on an output value o

Abstract: A combined toxic gas sensor and an oxygen sensor includes a sensor body 1 with a top plate 2 provided with a toxic gas diffusion barrier 3 leading to a chamber 7 from having an outlet aperture 5 registering with the diffusion barrier 6 of the oxygen sensor.

Abstract: A gas sensor including a housing containing at least a sensing electrode, a counter electrode, a test electrode, and electrolyte means in contact with such electrodes. The housing permits gas from the environment to flow to the sensing electrode. The gas sensor is operable either in a normal mode of operation in which potentials are applied to the electrodes for detecting when a gas to be sensed is present at the sensing electrode, or in a test mode of operation in which potentials are applied to the electrodes so that the test electrode generates a gas which flows to the sensing electrode to enable an indication whether the sensor is operating correctly.

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: The present invention relates to a reference electrode for a potentiometric electrode system, characterized in that the junction in contact with a sample solution is enlarged and an ion-sensitive membrane containing an ion selective material as a protective membrane for the inner reference solution is employed, which comprises a substrate; a metal layer; an insoluble metal salt layer; an insulating film for insulating the metal layer from an aqueous solution; a hydrogel serving as an inner reference solution; the junction on the hydrogel contacting with a sample solution; the ion-sensitive, protective membrane formed over all surface areas of the hydrogel, except for the junction, to separate the sample solution from the inner reference solution or act as an ion-sensing membrane upon the contamination of the junction, whereby the operational abnormality caused by junction contamination may be easily checked and fast activation may be achieved.

Abstract: Before starting an air-fuel ratio feedback control utilizing an air-fuel ratio sensor, activation of a wide-range air-fuel ratio sensor in an internal combustion engine is diagnosed by calculating heat transferred to and from the air-fuel ratio sensor, the output value of the wide-range air-fuel ratio sensor varies in response to oxygen concentration in exhaust which varies according to the air-fuel ratio of an intake air-fuel mixture of the internal combustion engine. The activation time from the starting of the engine until the air-fuel ratio sensor is activated is estimate based on the calculated result of the heat transfer. Alternatively, activation of the sensor is diagnosed under the condition that an output voltage of the oxygen concentration detecting unit of the sensor is fixed to a value either equal to or above a rich-side set voltage or equal to or under a lean-side set voltage, before starting the air-fuel ratio feedback control.

Abstract: This invention provides a method for monitoring the function and/or regeneration of a gas probe. The invention includes a measurement of first and second pump currents of the gas probe and a determination of a difference between the first and second pump currents (&Dgr;I). If &Dgr;I exceeds a pregiven value, then a saturation pump voltage is applied and the difference between a resulting pump current and a previously stored minimum pump current (&Dgr;I plus) is determined. If &Dgr;I plus exceeds a pregiven value, then a regeneration voltage is applied.

Abstract: Disclosed is an electrochemical sensor for detecting the concentration of an analyte such as glucose in a fluid test sample. The sensor involves a base as flow path for the fluid test sample having a working and counter electrode on its surface. The base is mated with a cover to form a capillary space to capture the fluid and the counter electrode has a sub-element located upstream in the flow path. When there is detected electrical communication only between the sub-element and the working electrode the meter, with which the sensor is in electrical communication senses that the capillary space has not completely filled with test fluid.

Abstract: A biosensor comprises a space part for sucking and housing a sample formed of two upper and lower plates, the two plates being stuck together by an adhesive layer, the space part for sucking and housing the sample being constituted so as to be partially opened in the peripheral part and partially closed by the adhesive layer, and has a working electrode having at least glucose oxidase immobilized thereon and a counter electrode on the same plane of the plate.

Abstract: An O2-sensor fault diagnosis apparatus and method therefor, which are capable of detecting wire breaking of an O2-sensor with reliability and successively performing fault diagnosis with minimal effect on an exhaust gas. An O2-sensor 19 detects concentration of oxygen contained in an exhaust gas of an engine 1. An ECU 20 controls a quantity of fuel supplied to the engine 1 through feedback control according to an output signal of the O2-sensor. A fault diagnosis portion changes an input resistance value of an input circuit that is connected to the O2-sensor 19 and constitutes the ECU 20 each time a control condition for determining that the O2-sensor 19 is in an inactive state is satisfied, determines that wire breaking occurs in the O2-sensor 19 only if the output voltage of the O2-sensor 19 exceeds a predetermined voltage, and activates an informing portion to send a notice showing that there is a fault in the O2-sensor 19.

Abstract: A measuring arrangement for measuring product parameters of a component in the epitaxial layer (28) of a wafer comprises measuring probe (3) on whose contact side (23) a recess (24) is installed, into which an electrolyte can be poured. The electrolyte produces an electrical connection between a contact body (11), which is charged with a signal from a pulsed-current source, and the surface (22) of the wafer (2). A detector (16) serves for detecting the light which is emitted by the component.

Abstract: The invention provides a bicarbonate-containing, crosslinker-free reagent composition which reverses and/or reduces sample handling effects, such as aeration-induced shrinkage and storage-induced swelling of cells in a whole blood sample, particularly for a blood sample requiring repeated sampling and/or subjected to long-term storage. The reagent composition serves as a diluent medium for a blood sample, or an aliquot or portion thereof. The pH of the reagent is in the range of about 7.2 to about 7.5, preferably 7.3. The stability of the pH 7.2-7.5 bicarbonate-containing reagent over time is maintained by storing the reagent in a flexible collapsible container which is impermeable to carbon dioxide and is comprised of a multilayered flexible material, preferably plastic, and attachable to a hematology analyzer.

Abstract: The invention relates to an amperometric electrochemical cell having a first insulating substrate carrying a first electrode, a second insulting substrate carrying a second electrode, said electrodes being disposed to face each other and spaced apart by less than 500 &mgr;m, and defining a sample reservoir therebetween, and wherein at least one, and preferably both, insulating substrates and the electrode carried thereon include an electromagnetic radiation transmissive portion in registration with said reservoir. The walls of the electrochemical cell may be formed from a thin metallic portion on a transparent substrate. Such cells are useful in providing visual confirmation of the validity of the electrochemical measurement.

Abstract: A gas sensor is described which is particularly well suited as a carbon monoxide (CO) sensor in a self test gas sensor. The sensor includes a number of aspects which may or may not be used in conjunction with one another. A first aspect is an embodiment which reduces electrical interference (or cross-talk) between a test or gas generating cell and a sensing cell. In one embodiment, baffles are provided to prevent cross-talk. In another embodiment a switching circuit ensures that a test gas generator is operational only when the gas sensor is disconnected from a current source. A second aspect is an embodiment which includes an improved wick which is in close proximity with an electrode and ensures electrolyte is always in contact with the electrode. In an alternate embodiment a solid polymer electrolyte is used between the electrodes. A third aspect is an improved catalyst which reduces the reaction energy and thereby renders the sensor more sensitive. The catalyst is also cheaper than platinum.

Abstract: A method and apparatus for determining the operating condition of a gas sensor apparatus including an amperometric electrochemical sensor operating normally in a potentiostat mode. By coating the sensor with a conductive coating or by varying one or more operating conditions, a response of the sensor can be determined and compared with sensor response while operating normally. This testing enables abnormalities in sensor operation to be determined, and failure of the sensor to be predicted.

Abstract: The invention provides a deterioration detector for an exhaust gas sensor capable of detecting an amount of change with age of an internal resistance and conducting deterioration judgment taking into consideration fluctuation between products and temperature dependency of the internal resistance of the exhaust gas sensor.

Abstract: The present invention provides a method and system for management of chemical materials by a company comprising providing a first data set containing which substances comprise the materials, providing a second data set containing which of the substances are to be controlled, providing a third data set containing a ratio of discharge of the controlled substances in a process and analyzing a preset amount of the materials in the process and determining a quantity of the controlled substances utilizing the first and second data set and determining an emissions quantity of the controlled substances utilizing the ratio and the quantity of the controlled substances, wherein the data sets are provided by an outsource company through a network.

Abstract: The quality of electrochemical measuring sensors with at least one measuring electrode, for example pH-sensors is checked in that the frequency response of the sensor impedance is measured over a frequency range (f1, f2). The frequency response or the value of an equivalent circuit diagram of the measuring circuit (1) computed from the frequency response are compared to reference values. Deviations from the reference values indicate an impairment or damage of the measuring electrode (2). Simultaneously proceeding from the membrane impedance the temperature (T) of the measuring electrode (2) and thus of the measuring fluid (F) is determined.

Abstract: A measuring probe for potentiometric measurements has a housing (2) of an electrically insulating material surrounding an enclosed space (4). Inside the space (4) are a primary reference element (6), a secondary reference element (8), an electrolyte (10), and an ion-permeable, micro-porous, high-viscosity polymer substance which, in combination with the electrolyte (10), forms a filler mass (16). The housing (2) has at least one opening (12) to the outside, through which the electrolyte (10) can be brought into contact with a sample solution on which a measurement is to be performed. The secondary reference element (8) is arranged so that the boundary (52) of an electrolyte-deficient region (54) advancing over time from the opening (12) towards the primary reference element (6) arrives at the secondary reference element (8) before reaching the primary reference element (6).

Abstract: Disclosed is an improved electrochemical sensor having a base bearing a working and counter electrode which provides a flow path for a fluid test sample. The working electrode has a reaction layer on its surface which contains an enzyme capable of reacting with an analyte to produce electrons which are received by the working electrode. The base is mated with a cover to form a capillary space into which the test fluid is drawn. The improvement involves configuring the working and counter electrodes so that a major portion of the counter electrode is located downstream on the flow path from the working electrode with the exception of a small sub-element of the counter electrode which is in electrical communication with the primary portion of the counter electrode and located upstream of the working electrode.

Abstract: A gas sensor comprises a main pumping cell for pumping-processing oxygen contained in a first chamber, a feedback control system for comparing a partial pressure of oxygen in the first chamber with a first reference value to control the main pumping cell so that the partial pressure of oxygen has a predetermined value at which NO is not decomposable, an auxiliary pumping cell for pumping-processing oxygen in the second chamber, and a measuring pumping cell for pumping-processing oxygen produced by decomposition of NOx.

Abstract: A method of determining remote gas concentration values from remote gas sensors. The method is particularly applicable to heated metal oxide sensors; however, it is not restricted to this type of sensor. A polynomial fit is made of a sensor's gas response curve for each sensor in the system. Usually this is a third order polynomial; however, any other order can be used. The sensors response at zero concentration is a zero or root of the polynomial. This root is factored out of the polynomial reducing it one degree. It is possible to factor out more than one real root if such a root is known further reducing the order of the polynomial. The coefficients of the reduced polynomial are scaled and stored as absolute values in binary words at the remote. At least one additional word is used to store exponents and signs. These words are transmitted to a central location on demand so that the gas response curve can be recreated.

Abstract: Periodic forced stimulations are asserted on setpoint values for a lambda control and a system response of a lambda control loop is simulated by a model that includes a sensor delay time as the model parameter. Amplitude gains of the model and the system are compared with each other and adapted according to the result of the comparison of the model parameters. If the adaptation value lies above a threshold, a lambda probe is classified as defective.

Abstract: A failure determining apparatus of a gas-insulated electrical appliance determining a failure, having a cylindrical metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spaces insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprising a high-speed developing sensor which detects a high-speed phenomenon caused by a failure such as a ground-fault or a short-circuit within the gas sections; a first failure determining circuit which determines the presence of a failure from an output of the high-speed developing sensor; a low-speed developing sensor which detects a low-speed phenomenon caused by a failure such as a ground-fault or a short-circuit within the gas sections; a second failure determining circuit which determines the presence of a failure from an output of the low-speed developing sensor; and an arithmetic control circuit which identifie

Abstract: In order to correct the characteristic of a linear lambda probe which is arranged in an emission control system of an internal combustion engine upstream of a catalytic converter, in an overrun fuel cut-off phase the throttle valve and/or at least one gas exchange valve of the internal combustion engine is opened, and the signal of the lambda probe is assigned to the lambda value corresponding to the oxygen concentration of the ambient air. It is then possible, together with a conventional trimming controller which corrects the assignment of the signal to lambda=1, to correct the gradient of the characteristic.

Abstract: Apparatus for measuring concentration of oxygen includes a plurality of status displays, identifying concentration status relative to a plurality of thresholds, an alarm for immediate and prominent identification of status relative to a threshold of particular significance, and a quantitative display indicative of an actual concentration. Although measurements are performed and results are indicated relative to a number of thresholds, only a single calibration procedure is required, using only a single calibration gas. The apparatus is calibrated by adjusting a circuit parameter of one of the circuit components to vary a sensed output value to correspond to a narrow range surrounding the known concentration of the calibration gas. Both the circuit parameter and the actually sensed output value are stored. In a monitoring operation, the circuit parameter is retrieved to reset the circuit component to its calibrated setting.

Abstract: An electrochemical cell sensing circuit for an electrochemical cell having a working electrode, a counter electrode and a reference electrode in an electrolyte, which in use, when a gas to be analysed is introduced into the cell, generating a current between the counter electrode and the working electrode, and a potential at a position in the electrolyte is sensed by the reference electrode.

Abstract: An operational amplifier (34) has its inverting input connected to a electrochemical gas sensor (38) for amplifying the current produced thereby in response to presence of a predetermined gas. In order to determine whether a sensor (38) is indeed present and that a sensor present is serviceable, a transient is applied to the non-inverting input of the operation amplifier (34). The presence or absence of the sensor (38) alters the transfer function of the operational amplifier (34) in respect of the test signal. If a serviceable sensor (38) is present, the gain of the operational amplifier (34) is high for the transient resulting at square pulse output. However, if a serviceable sensor (38) is not present, the gain of the operational amplifier (34) is relatively low and the transient retains its original form. Consequently the presence of a serviceable sensor (38) can be determined from the output of the operational amplifier (34) in response to the transient test signal.

Abstract: The invention is directed to a diagnostic arrangement for a potentiometric, electrical exhaust-gas probe for the control of combustion processes with a periodic change of the composition of the combusting air/fuel mixture between oxygen deficiency and oxygen excess. The exhaust-gas probe is heated by an electric heater and outputs a probe signal when the exhaust-gas probe operates without fault which changes between a first region of high signal values (oxygen deficiency) and a second region of low signal values (oxygen excess) with the first region and the second region being separated by a third region of values. A fault announcement is outputted when the probe signal lies within the third region longer than a pregiven longest duration. A fault announcement is also outputted when changes of the current supplied to the electric heater occur within the pregiven longest duration and when the probe signal has temporarily left the third region of values after the change of the heater current.

Abstract: A method and device for testing the quality of a sheet-like element comprising a membrane are presented. The quality test is limited to a part-area of the sheet-like element. A useful material is fed to one side of the sheet-like element via an outlet orifice corresponding to the part are to be tested. The method can be used in the production of large-area membranes or membrane/electrode units (MEU) provided for use in fuel cells. The quality test can take place in a simple way even during production of these sheet-like elements. Faults during production can be detected at an early stage and the production parameters changed accordingly. In the case of testing an MEU for a fuel cell, fuel gas can be applied to one side of the MEU in a punctiform manner. Oxygen of the ambient atmosphere located on the other side can serve as an oxidation gas.

Abstract: A highly accurate, long life, low cost gas sensor is disclosed, particularly useful for measuring carbon monoxide and other toxic gases in an environment. The gas sensor has a first, sensing electrode and a second, counting electrode. Positioned between the first and second electrodes is an ion conducting, solid electrolyte membrane. In response to the presence of a toxic gas introduced to the first electrode, an electric signal is produced between the first electrode and the second electrode. The electric signal changes in response to changes in the concentration of the toxic gas. Detection circuitry measures the electric signal to determine the concentration of the toxic gas. An electrically conductive, hydrophobic top membrane electrically connects the first electrode to the detection circuitry while preventing liquid water from contacting the first electrode. An electrically conductive, hydrophobic bottom membrane electrically connects the second electrode to the detection circuitry.

Abstract: A modified universal exhaust gas oxygen sensor, referred to herein as a CEGA sensor, is provided which can be used to measure the concentration of a variety of components of a gaseous fuel emission including CO, CO.sub.2, O.sub.2, H.sub.2, and H.sub.2 O. The CEGA sensor employs at least one additional electrode on a ceramic substrate which possess a different catalytic activity relative to the electrodes that normally found on a UEGO sensor. The ceramic substrate may be made of any suitable ceramic and is preferably made of zirconia. The difference in catalytic activity between the additional electrode(s) and the electrodes native to the UEGO sensor create an oxygen gradient which enables a measure of combustion completeness to be calculated. In combination with an air/fuel ratio measured by the sensor, the concentrations of different components in the emission can be calculated.

Abstract: An air-fuel ratio sensor system is diagnosed for the presence/absence of an abnormality on the basis of a reference voltage appearing at one end of a current detecting resistor and a detection voltage appearing at the other end of the current detecting resistor for detecting a current output by an air-fuel ratio sensor. If the reference voltage is outside a normal range and higher than the detection voltage, the air-fuel ratio sensor system is determined to be in a rich abnormality. If the reference voltage Vafon is outside the normal range and lower than the detection voltage, the air-fuel ratio sensor system is determined to be in a lean abnormality. If the reference voltage is within the normal range and a state of the detection voltage being close to a power supply voltage has been continuing for a predetermined period of time, the air-fuel ratio sensor system is determined to be in a circuit-shorting.

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: A method of detecting a deteriorated condition of a wide range air-fuel ratio sensor is provided. Firstly, a current is applied to an electromotive force cell to detect a voltage Vs0 across electrodes on opposite side surfaces of the cell. Application of the current is suspended, and a voltage drop Vsd1 across the electrodes is detected after lapse of a time ranging from 10 .mu.s to 1 ms after the application of the current is suspended. Based on the voltage drop Vsd1 is detected a first resistance value Rvs1 equated to the temperature of the electromotive force cell. Further, after lapse of a time ranging from 10 ms to 50 ms after the application of the current to the electromotive force cell is suspended, a voltage drop Vsd2 across the electrodes of the electromotive force cell is detected. Based on the voltage drop Vsd2 is detected a second resistance value Rvs2 equated to an internal resistance of the electromotive force cell including a resistance component resulting from deterioration.

Abstract: A method by which an oxygen measuring instrument can test the functionality of the oxygen sensor. Oxygen sensors of the galvanic type operate by consumption of an internal easily oxidizable anode, such as lead or cadmium. Failure of the sensor due to complete consumption of all of the anode material, such that the oxygen sensor is no longer able to detect oxygen, is often rapid with little warning. This invention describes an electrical test, which may be performed in-situ on the oxygen sensor by the instrument, which provides a means for detection of an imminent failure, while the sensor is still operational.

Abstract: A gas sensor comprises a main pumping cell for pumping-processing oxygen contained in a first chamber, a feedback control system for comparing a partial pressure of oxygen in the first chamber with a first reference value to control the main pumping cell so that the partial pressure of oxygen has a predetermined value at which NO is not decomposable, an auxiliary pumping cell for pumping-processing oxygen in the second chamber, and a measuring pumping cell for pumping-processing oxygen produced by decomposition of NOx.

Abstract: A calibrated medical sensing catheter system in which a catheter-mounted sensor may be calibrated in a simple and reliable manner. In one embodiment the calibration may be performed using a disposable vessel containing two volumes of calibrating fluid, each volume separately accessible by the sensor to be calibrated. Preferably, such a vessel takes the form of an elongated tube having a first volume at one end and a second volume at the other end, each volume containing distinct calibrating fluids. Each volume may be accessed through the respective ends of the tube by introducing a sensor through a pierceable membrane, such as a foil-plastic membrane or seal. In an alternative embodiment the calibrated vessel takes the form of an elongated cylinder having two separate volumes of calibrating fluid separated by a common pierceable membrane or seal.