Abstract: An ion-measuring apparatus for use in processes, characterized by comprising 3 or more ion-measuring electrodes for measuring a same one ion contained in a same one sample, means for computing a mean value of measured values obtained by means of said ion-measuring electrodes, an indicating portion for indicating the computed result, means for judging an existence of an abnormality in the ion-measuring electrodes and an alarm for emitting a maintenance alarm when the abnormality occurs in any one of the ion-measuring electrodes so that the ion-measuring electrode, which has been judged to be abnormal, may be excluded to continue a measurement by means of remaining ion-measuring electrodes.

Abstract: The apparatus employs a method for accurate, reproducible analytical solution evaluation eliminating the need for a reference sensor by determining the activity of selected species employing species specific sensors and species combination sensors in conjunction with Nernst-type equations. The apparatus includes sensor structures for elimination of edge effects to signals thereby yielding accurate, reproducible measurements, and a cartridge structure adapted to incorporate an array of the new sensors for employment of the new method where the cartridge is particularly adapted for miniaturization, maintaining a fixed volume of solution for analysis and providing an anaerobic testing environment. Lastly, a compact instrument embodying miniaturization especially adapted for field use and use of the cartridge is provided herein.

Abstract: A coated polarographic sensor is calibrated by exposing the sensor to calibration media having known temperatures and species chemical potentials. The sensor is allowed to equilibrate with respect to the calibration media. After equilibration, the sensor is polarized with respect to a reference electrode and the resulting transient and steady state electrochemical currents are monitored. A transient calibration equation characterizing transient sensor performance is derived from the transient electrochemical current, and a quasi-steady state calibration equation characterizing steady state sensor performance is derived from the steady state electrochemical current. The transient current of the sensor is independent of the thermophysical properties of the species in the medium so that the transient current can serve to correct the quasi-steady state calibration equation for the sensor in situ.

Abstract: An output correction method for a proportional-output type O.sub.2 sensor including an oxygen concentration detecting element formed by an oxygen-pumping element and a cell element, each of the oxygen-pumping element and the cell element being composed of a wall of a solid electrolytic material having oxygen ion-conductivity, and a pair of electrodes having the wall interposed therebetween. The oxgen-pumping element is supplied with an output voltage corresponding to a difference between a voltage developed between the electrodes of the cell element and a predetermined reference voltage, and current flowing in the oxygen-pumping element is detected. A correction resistance supplies information indicative of a deviation of an air-fuel ratio detected by the sensor with respect to a predetermined reference air-fuel ratio. A correction value is determined on the basis of the information and the direction of flow of the current. The detected current is corrected by the use of the determined corrected value.

Abstract: In a real time, on-line pH measurement of a process solution, a system provides a continuous data of the physical condition of the pH sensor. The system includes a pH sensor having a glass membrane disposed in the process solution and two electrodes in the solution adjacent the sensor. The two electrodes in the solution are periodically driven by a short time duration dc signal producing a dc current between the two electrodes. This action results in electrolysis ofo the H.sub.2 O molecules of the solution at the two electrodes and a resulting decrease in hydrogen ion concentration (a rise in pH value) in the region of the sensor. The sensor response to the increase in pH in the solution is a direct indicator of the complete sensor and system performance and is monitored and analyzed. Visual readouts and threshold alarm circuits are provided which indicate changes in the sensor response to the pH change indicative of a sensor or system degradation or fault.

Abstract: The air-fuel (A/F) ratio controller of an internal combustion engine related to the invention detects occurrence of abnormal condition in a heater on the basis of the resistance value of this heater which heats an oxygen sensor generating a specific voltage responsive to the difference of oxygen concentration between atmosphere and exhaust gas of the engine and of an oxygen pump allowing the pump current flow in order that the voltage can be the predetermined value. If abnormal condition arises in the heater, the A/F ratio controller stops fuel feedback control operation. The A/F ratio controller related to the invention forms a Wheatstone bridge circuit which includes the heater mentioned above and detects occurrence of an abnormal condition in the heater on the basis of the equilibrium condition of signal outputted from the Wheatstone bridge circuit.

Abstract: A measuring probe in which the electrolyte is in the form of a highly viscous gel produced in situ from an ion-permeable polymer and a neutral salt suspension. Homogeneously suspended neutral salt particles in the gel cause the gel to have a turbid appearance which disappears progressively as the suspended neutral salt particles pass into solution, thus indicating at all times the state of aging of the electrolyte. The additional presence of silica gel renders the probe potential resistant to pressures in excess of 10 bars.

Abstract: Quantitative determination of ozone contained in a fluid by an amperometric method comprises the steps of:(A) providing an amperometric cell having a sensing electrode, a counter electrode, an aqueous electrolyte in contact with the sensing electrode and the counter electrode, and a membrane that is substantially impermeable to the electrolyte but permeable to gaseous media including ozone and oxygen for containing the electrolyte within the cell and for separating it from the fluid maintained external to the cell;(B) providing in the aqueous electrolyte a redox catalyst for chemically transforming the ozone upon its permeation through the membrane into an intermediary electroactive species capable of generating upon reaction with the sensing electrode an indicative electrical signal in proportion with a concentration of the ozone in the fluid;(C) applying a predetermined potential across the sensing electropde and the counter electrode;(D) measuring a cell current generated by reaction of the intermediary el

Abstract: A method and system are provided for validating monitoring instruments whereby the validating solution contains other analytes normally present in an industrial liquid. The solution is checked for water purity prior to addition of other analytes and is checked for homogeneity after mixing the analytes.

Abstract: A two-part test cartridge for use in a centrifugal analyzer for measuring the concentration of different electrolytes in blood or blood serum samples has one part which is disposable and which is characterized by a sample entry port, one or more filled calibrant chambers, a waste chamber and passages between various chambers; and a second, mating part which is reusable and which is characterized by an ISE, a power supply and circuitry therefor, and a series of chambers and passages adapted for communication with the series of chambers and passages in the disposable part.

Abstract: A modular multi-channel automated medical analyzer device is disclosed, characterized by use of an ion selective electrode and/or enzymatic electrode/wash cell system which permits rapid analysis of various substances of interest contained within undiluted body fluids such as whole blood, serum and/or plasma. The ion selective electrode and/or the enzymatic electrode are disposed upon a probe which automatically axially reciprocates downwardly in a simple manipulative motion between an open-ended reference wash cell and a sample cup bearing the body fluid specimen to be analyzed. The wash cell includes an inlet port and one or more outlet ports through which is circulated an aqueous solution bearing a known concentration of the substance to be measured to provide a reference calibration medium as well as a probe washing medium.

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: A system for real time, on-line dissolved oxygen (DO) measurement of a process solution provides continuous data of the physical condition of the DO sensor and of the entire system performance. A DO sensor is disposed in the solution with two external electrodes adjacent thereto. A time-varying low level signal is applied to one electrode producing a current through the sensor membrane and grounded electrode, which is detected by a cross-correlation circuit to monitor the membrane impedance. The other electrode is periodically driven by a short, low level dc pulse, producing electrolysis of the water between the two electrodes, and generating a small, repeatable amount of oxygen ions. The sensor response is analyzed providing a direct indication of the sensor and system performance.

Abstract: A method and system are provided for validating monitoring instruments whereby the validating solution contains other analytes normally present in an industrial liquid. The solution is checked for water purity prior to addition of other analytes and is checked for homogeneity after mixing with analytes.

Abstract: A simple inspection device is constituted for inspection of an analyzer for measuring ionic activity by using an ionic activity measuring device provided with at least one ion selective electrode pair for generating potential corresponding to ionic activity fo a predetermined ion, and a porous bridge for associating the electrodes of the ion selective electrode pair with each other, and by contacting potential difference measuring probes respectively with the electrodes of the ion selective electrode pair, thereby to measure a difference in potential between the electrodes. The simple inspection device comprises a supporting member having outer dimensions approximately equal to ther outer dimensions of the ionic activity measuring device, and an electrically conductive member supported on the supporting member for short-circuiting across the potential difference measuring probes when the potential difference measuring probes are contacted with the electrically conductive member.

Abstract: Disclosed is a method and apparatus which can detect progress of degradation of a sodium-sulfur cell and predict possibility of final breakdown of the cell in a very near future before such a final breakdown of the cell actually occurs. The method and apparatus for diagnosing the presence or absence of an abnormal state in the sodium-sulfur cell, containing a porous electrical conductive material impregnated with molten sulfur or sodium polysulfide as its positive electrode reactant and containing sodium as its negative electrode reactant, comprises observing the operating voltage of the cell during charging and discharging so as to detect occurrence of a minute ripple in the operating voltage, and, when the amplitude of the ripple and the frequency of occurrence of the ripple increases as a result of repeated cycles of charging and discharging, deciding that degradation of the cell has progressed to an extent that final breakdown of the cell will occur in a very near future.

Abstract: This invention relates to solid-state electrode or micro-electrode sensor apparatus for measuring certain characteristics of an aqueous sample such as a body fluid or a blood sample and more particularly to such apparatus which employs a disposable cartridge containing a sensor or a bank of sensors for such characteristics and reagents used to calibrate the sensors.

Abstract: In a resistive-sensor type indicator having a resistive sensor whose resistance changes according to a quantity to be measured and an indicator for indicating a sensor output voltage developed across the resistive sensor, when the resistive sensor is open due to disconnection or malconnection of the resistive sensor, the indicator indicates a maximum reading, thus resulting in a problem such that the user cannot recognize the abnormal state. To overcome this problem, a novel trouble detecting circuit is additionally incorporated in the indicator. The circuit comprises a comparator for outputting an abnormal signal when the sensor voltage exceeds a reference voltage and a transistor for grounding the resistive sensor in response to the abnormal signal. Therefore, the indicator indicates a minimum reading in case of resistive sensor trouble.

Abstract: The combination of a measured value transmitter unit, a metering unit and a control unit enables all maintenance measures which become necessary during the course of process monitoring, to be carried out with little expenditure of labor and time and without removing the sensor from the container containing the measured medium. In addition, this combination, in which all functions necessary for carrying out the maintenance can be initiated and/or controlled by pneumatic signals, permits at least partial automation of the maintenance.

Abstract: A simple inspection device is constituted for inspection of an analyzer for measuring ionic activity by using an ionic activity measuring device provided with at least one ion selective electrode pair for generating an electrical potential corresponding to ionic activity of a predetermined ion, and a porous bridge for associating the electrodes of the ion selective electrode pair with each other, and by contacting potential difference measuring probes respectively with the electrodes of the ion selective electrode pair, to thereby measure a difference in potential between the electrodes. The simple inspection device employs a supporting member having outer dimensions approximately equal to the outer dimensions of the ionic activity measuring device, and an electrically conductive member supported on the supporting member for short-circuiting across the potential difference measuring probes when the potential difference measuring probes are contacted with the electrically conductive member.

Abstract: A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein.

Abstract: A clinical chemistry analyzer system for blood chemistry analysis is disclosed. Two major parts comprise the system. One part is a discardable sensor cartridge which contains a bank of sensors, calibration fluid containers, conduit means and an external peristallically pumpable tube section. The other part is an analysis machine which interfaces with the discardable cartridge and has means to drive the peristaltic pump as well as means to interface with the sensors of the cartridge to provide a readout therefrom. The system is adapted to be made part of a heart/lung machine sustaining a patient in order to sample and monitor the venous and arterial blood flow thereof.

Abstract: The present invention is an improved method and apparatus for condition sensing and displaying a numeric value associated with the sensed condition wherein the improvement comprises (1) circuitry calibrating the display of the numerical value associated with the sensed condition to a numerical value associated with the sensed condition in a normal ambient environment, while the sensor is within the normal ambient environment; and (2) circuitry for calibrating the display of the numerical value of the sensed condition to a numerical value associated with the sensed condition in a known offset environment which is different than the normal ambient environment, while the sensor is in the known offset environment.

Abstract: A testing method and apparatus for testing the condition of electrodes and their conductors in ion sensitive measuring or controlling systems, wherein the measuring circuit is disruptive and replaced by an impedance measuring circuit containing only one electrode, so that also failures of, for example, reference electrodes, soiling and deposits, and electrolyte loss, can be determined. The arrangement has sufficient accuracy to detect faults, defects and failures as they slowly come into existence.

Abstract: Method for the protection and/or monitoring of a reference system with reference electrode in analytical measuring techniques, and reference system therefor, wherein an additional monitor electrode is provided for self-monitoring the outer bridge electrolyte (16) for contamination, the additional monitor electrode being arranged to permit measuring of the pH value (pX value) of the bridge electrolyte which is adjusted to the same pH value (pX value) as the reference electrolyte. A fault signal is released when a potential difference occurs between the additional electrode and the real reference electrode of the reference system. Further, the bridge electrolyte is preferably connected with the measured solution in pressure-balancing relationship via a flexible diaphragm arranged in the wall of the vessel containing the bridge electrolyte which diaphragm may also be designed to serve as mounting for the said first diaphragm.

Abstract: A system for testing plastic cuvette belts for leak holes in the cuvettes comprises an array of conductive probes which are inserted into respective ones of a group of adjacent cuvettes. Alternate probes are biased to opposite high potentials sufficient to create arcing between the probes through any faulty seal in the cuvettes. A grounded electrode outside the cuvette enables holes to the outside to be detected also.

Abstract: Analysis of a series of samples is carried in an electrode cell (10) containing an ion-selective electrode (11). A base solution, to which a trace of the ion to be measured has previously been added, is run into the cell (10). To perform an analysis a small volume of solution, containing a known concentration of the ion is added, followed by an identical volume of sample. The pX or mV measurement before and after each of the two additions is recorded and the analytical result calculated. After analyzing the first sample, the cell is drained, without rinsing and the second sample analyzed in the same way. No blank determination is required. In more sophisticated versions of the technique, at least two additions of standard are made, one before and one after the sample.

Abstract: A single-use sensing device for a clinical chemistry analyzer system includes a carrier which supports a capillary passage. Species selective sensors are located within a test chamber portion of the capillary passage. A rotatable multichamber reservoir having a calibrant chamber for holding calibrant fluid and a sample chamber for containing a sample fluid is rotated first to a calibrant test position and then to a sample test position. In the calibrant test position, the calibrant chamber is connected to the inlet end of the capillary passage to draw calibrant fluid into the test chamber. In the sample test position, the sample chamber is connected to the inlet end to draw sample fluid into the test chamber and purge the calibrant fluid from the test chamber. A set of sensor readings are taken at each position, and concentration values are derived from the two sets of readings.

Abstract: A testing module is provided having units which can be arranged seriatim to provide narrow through passageways linked to each other for quantitative determination of analytes passing through the units as by electrical testing with electrodes. Auxiliary passageways are preferably used in one unit to allow flushing of a first sample chamber without contamination from a second sample chamber. An electrode holder carries a membrane backed by a gel to aid in electrically linking the membrane to an electrode and to support the membrane in a substantially planar condition in use.

Abstract: A monitor (26) for use in a vehicle to check the operation of an oxygen sensor (20). The monitor (26) has a regulator (64) that changes the fluctuating voltage associated with a vehicle electrical system into a stable voltage source. An amplifier (68) receives an output signal from the oxygen sensor (20) and generates a buffered output signal. A comparator (70) compares the buffered output signal with a reference signal. When the buffered output signal is equal to the reference signal, the source voltage from the regulator (64) activates a diode (40) to inform an operator that the output voltage of the oxygen sensor (20) is within acceptable operating limits.

Abstract: A halogen ion concentration in a solution is measured by bringing halogen ion-selective detection means comprising a silver/silver halide electrode, and a reference electrode into a solution whose halogen ion concentration is to be measured, and measuring an electromotive force of the halogen ion-selective detection means in the presence of silver ions dissolved in the solution. The electromotive force corresponds to the halogen ion concentration in the solution.

Abstract: Apparatus for calibrating an ion analyzer comprises a calibration cell having defined therein a first volume for measuring an ion concentration of a sample when the instrument is operated in a monitoring and a second volume for measuring the ion concentration when the instrument is operated in a calibration mode. The first volume is included in, and forms part of, the second volume so that the matrix for the calibration measurement is essentially identical to that for the sample measurement. A double known-addition is used during the calibration mode to determine the calibration parameters.

Abstract: A conductive metal oxide electrode can be calibrated by immersing the electrode and a reference electrode in a solution of known pH and applying to them a setting potential which is approximately equal to the steady state potential that would be observed for that electrode with respect to the reference electrode in a solution of that value of pH.

Abstract: To permit calibrating and testing a current-limiting sensor in situ, the sensor is exposed, from time to time, to ambient air forming a standard gas, and the output thereof compared with a standard, for example by connecting a resistor (4) of standard value in circuit therewith or for recalling from a memory (23) in a microcomputer (22) standard conditions; upon determination of a deviation between output from the sensor (2) when exposed to the standard gas--typically air--and the theoretical value as stored, the theoretical or reference value is reset if the deviation is within a predetermined limit or, otherwise, an alarm output is provided. The tolerance limits can be set in such a way that a first alarm output is provided in a narrow tolerance, thus indicating drift of the sensor toward eventual malfunction, and permitting utilization of the sensor for long lifetime, while providing advance warning of imminent failure.

Abstract: The disclosed apparatus quickly measures ionic concentration of an electrolyte with an ion sensitive electrode means, by using a number of measuring cups disposed along a circle on a turntable and a series of treating stages fixed along but outside the turntable so as to face different measuring cups as the turntable stops at different angular positions, whereby various treatments necessary for the ionic concentration measurement are carried out simultaneously in parallel at different measuring cups, so as to shorten the measuring time of the ionic concentration.

Abstract: Systems and methods for detecting and eliminating latent and existing short circuit current paths through photovoltaic devices of the type including at least one semiconductor region overlying a substrate and a layer of conductive light transmissive material overlying the at least one semiconductor region are disclosed. The latent paths are first converted to existing short circuit current paths by applying a bias voltage to the devices. The short circuit current paths which are eliminated extend through the at least one semiconductor region from the substrate to the layer of conductive light transmissive material. The resistivity of the short circuit current paths is increased substantially at the interface between the conductive light transmissive material and the semiconductor region by isolating electrically the conductive light transmissive material from the short circuit current path.

Abstract: A compensator device for providing direct and automatic correction of electrolytic gas sensor performance anomalies caused by exposure of the sensor to high levels of ionizing radiation. The compensator device, which compensates for changes in sensor performance while operating in a radiation field, provides an electromotive force which directly cancels that portion of the electromotive force developed by the active electrolytic gas sensor produced by the radiation rather than by presence of the gas. The compensating device is constructed in the same configuration as the active electrolytic sensor with the exception that the sensing electrode of the compensating device is not exposed to the sample gas environment. The sensor and compensator device are connected in a circuit such that their electromotive forces oppose one another, thereby determining the difference between the signals so that the radiation induced component is removed, and only the signal representing the partial pressure of gas remains.

Abstract: An electrochemical sensor system includes a high impedance ion selective electrode and an electrode test circuit that has an isolation capacitor connected between the output signal lead from the ion selective electrode and a test voltage terminal, and a monitoring circuit connected to respond to the output signal from the electrode. The isolation capacitor is a high quality capacitor and provides a shunt impedance that is much higher than the maximum electrode impedance. A voltage transition at the test voltage terminal is coupled by the isolation capacitor to the output lead and the resulting decay rate of the voltage transition on the output lead is monitored to provide an indication of the quality of the electrode.

Abstract: This invention provides a calibration unit for generating known concentrations of an oxidizing or a reducing gas in an inert carrier gas. THe gas-generating electrode is sandwiched between an ion-exchange membrane and a porous diffusion membrane for minimizing the liquid layer thickness around the electrode and for regularizing the rate of diffusion of the gas generated. The present invention is especially useful for calibrating gas sensors which detect, measure, and monitor the concentration of a gas in the atmosphere, and for providing an accurate low concentration of gas for use wherever desired.

Abstract: A method for in situ recalibration of a polarographic type electrochemical measuring system having a fourth electrode which includes adjusting the sensitivity of the system so that the measured value of a standard sample is correct and then measuring the transient response of the cell under those known sample conditions. A measurement of the transient response is then made for recalibration under unknown sample conditions with a readjustment of the sensitivity of the system in accordance with the change in the value of the transient response.

Abstract: A method for detecting low levels of plastic deformation in metal articles comprising electrolytically etching a flow free surface of the metal article with nital at a current density of less than about 0.1 amp/cm.sup.2 and microscopically examining the etched surface to determine the presence of alternating striations. The presence of striations indicates plastic deformation in the article.

Abstract: The measuring electrode to be checked is polarized cyclically with an alternating voltage and the maximum amplitude of the electrode current as occuring during cyclical polarization is directly used as a measure for the metrologically relevant condition of the electrode.

Abstract: The present invention relates to electro-analytical measuring equipment for the determination--by means of one or more measuring cells comprising sensing elements of chemical similar composition, being in constant galvanic contact with each other--of the concentration and ion-activity of solutions or of the partial pressure of gases. The sensing elements are in contact with sample or with one or more standardizing media separated in time or space. At least two reference electrodes are in direct or in indirect contact--through electrolite--with sample and standardizing medium. The reference electrodes join, in a given case, to electronic signal processor comprising arithmetic unit calculating, by fault compensation, value of one or more parameters to be measured.

Abstract: An air/fuel ratio control system including an oxygen sensor disposed in the exhaust gas to provide a feedback signal. The oxygen sensor is of the solid electrolyte concentration cell type having a heater and is operated with supply of a DC current to the concentration cell to maintain a reference oxygen partial pressure therein. A fuel feed control circuit in this system shifts its closed-loop control function to open-loop aiming at a lower air/fuel ratio if the output of the oxygen sensor continues to indicate that actual air/fuel ratio remains on one side of the intended air/fuel ratio due to breaking of the heater.

Abstract: An electro-analytical measuring process and apparatus for the determination of the concentration and the ion-activity of stationary or flowing solutions or of the partial pressure of gases. The measuring cell of the measuring equipment--connected to an electronic signal processor--comprises, in addition to one or several sensing elements and reference electrodes, at least one fluid clutch capable of galvanically short-circuiting one or more parts of the measuring chain. The measuring cell of the measuring equipment comprises, in a given case, integral sensing unit and standardizing media, being in contact with sensing elements. Further, a control unit for programming short-circuiting belongs to the measuring cell, a fault compensating unit producing signals is connected to the control unit--for calculating the value of the parameter to be measured--is connected to the output of the fault compensating unit.

Abstract: A method and apparatus are disclosed for determining sulfur dioxide content in a gas sample. The apparatus is a polarographic- type one having first and second tubular chambers. The first chamber has a gas inlet. Gas coming therein causes an electrolyte to circulate around the two chambers with the second chamber having a sensing electrode and a counter electrode therein.

Abstract: Methods and apparatus are provided for sensing gases in the environment wherein electrochemical sensing procedures are utilized not only for monitoring ambient continuously for the presence of such gases; but also, for the periodic automatic recalibration and self-adjustment of the sensing instrument, as required, to accommodate changing conditions with time. Such accommodation includes not only changes in the instrument itself, but also changes in the environment affecting the accuracy of the monitoring function. The instrument is connected with a microprocessor, or other information storage or retrieval instrumentation which controls the periodic recalibration by measuring, separately from the monitoring function, the electrochemical response to a sample of the gas being monitored, and by adjusting the subsequent instrument readings to reflect the recalibration. During this recalibration procedure, the instrument can be adjusted to zero reading for accommodating drift, as will be understood.