Abstract: The inventive electrochemical sensor for determining the concentration of an oxidising gas in the studied gas or liquid comprises a body containing an electrolyte and measuring and counter electrodes contacting said electrolyte. The counter electrode contains carbon material and has a potential equal to or higher than 750 mV when it is measured in relation to a hydrogen reference electrode in the same electrolyte. The inventive method for producing said electrochemical sensor and determining the oxidising gas in the studied gas is also disclosed.

Abstract: Oxygen concentration measurement is carried out over a broad range by an instrument utilizing a zinc-air cell having a lower-than-nominal potential difference imposed across its electrodes by a shunt branch incorporating the source-drain circuit of a field effect transistor (FET). A feedback circuit is used to improve linearity of the output and cell life without sacrificing the broad dynamic range achieved by the use of the FET shunt branch.

Abstract: A multi-gas sensor device for the detection of dissolved hydrocarbon gases in oil-filled electrical equipment. The device comprising a semiconductor substrate, one or more catalytic metal gate-electrodes deposited on the surface of the semiconductor substrate operable for sensing various gases, and an ohmic contact deposited on the surface of the semiconductor substrate. The semiconductor substrate comprises one of GaN, SiC, AlN, InN, AlGaN, InGaN and AlInGaN. A method for sensing gas in an oil-filled reservoir of electrical equipment, comprising providing a sensor device, immersing the sensor device in the oil-filled reservoir, allowing the gases emitted from the oil to interact with the one or more catalytic metal gate-electrodes, altering the gas as it contacts the catalytic metal gate-electrodes and altering the sensitivity of the sensor.

Abstract: A chemical sensor selectively detects an analyte in a solution. The sensor comprises a flow-through chamber, a selective membrane, a transducer, an inlet for a liquid flow containing a recognition element, and an outlet. To detect an analyte in a solution, a recognition element is contacted with the solution containing the analyte via a selective membrane. This results in a response detectable by a transducer. The recognition element is injected into a flow, and the flow is passed into a flow-through chamber comprising the transducer and the selective membrane, where it contacts the analyte passing from the solution outside the chamber. The recognition element and the analyte interact to provide a signal that is detected by the transducer. The chemical sensor is used for detecting analyte(s) in a reactor system, a flow system or in an in vivo system.

Abstract: The concentration of dithionite can be fast and accurately measured in a sample by a method wherein a predetermined amount of peroxide is added to said sample, following which catalase is added to said sample in an incrementally growing dose during a predetermined time, monitoring the production of oxygen in the sample, and recording the onset of oxygen production as well as the amount of oxygen produced as a function of time. The recorded values are then taken as a measure of the amount of dithionite present in the sample.

Abstract: A sensor is described for determining the concentration of a gas in gas mixtures. The sensor has a measurement electrode and a reference electrode, as well as a polymer layer which is in contact with the gas mixture and the measurement electrode. A pH-sensitive electrode is provided as the measurement electrode.

Abstract: A sensor (1) for measuring O2 concentrations in liquids (2) has a working electrode (3), with a counterelectrode (4) and with a reference electrode (5), wherein the working electrode (3) and the counterelectrode (4) are in contact with the liquid (2). The reference electrode (5) is separated from the liquid (2) by a diaphragm (6). The reference electrode (5) measures a polarization voltage effectively acting at the working electrode (3) and is connected to a potentiostat regulating the potential between the working electrode (3) and the counterelectrode (4). The reference electrode (5), the working electrode (3) and the counterelectrode (4) are arranged coaxially to one another, wherein the working electrode (3) and the counterelectrode (4) are arranged around the reference electrode (5).

Abstract: An electrochemical sensor (A, A′) is specific for the detection of peroxyacetic acid in a solution which also contains hydrogen peroxide. A potential is applied between a reference electrode (120, 120′) and a working electrode (118, 118′). A read voltage (FIG. 7) is selectively pulsed across a counter electrode (122, 122′) and the working electrode. The current flowing between the working electrode and the counter electrode is dependent on the peroxyacetic acid concentration in the solution (FIG. 6). By careful selection of the read voltage, the contribution of hydrogen peroxide to the current flow is virtually negligible. The sensor effectively measures peroxyacetic acid concentrations in the range generally employed in sterilization and disinfection baths (100-3000 ppm.).

Abstract: An apparatus for determining a component present in a liquid sample in free state or bound to constituents, preferably for measuring the SO2 content in the sample, has a locating space for the liquid sample, a sensor preferably responding selectively to the component, preferably based on an electrochemical cell, and a gas piping system via which a carrier gas can be passed from the locating space through the sensor (FIG. 1).

Abstract: An electrochemical cell that receives an inlet stream of air and produces an outlet stream of a high oxygen concentration of gas. The cell is made up of a plurality of layers and preferably a porous electrolyte comprised of yttria stabilized zirconia (YSZ) that allows only oxygen ions to pass therethrough and which is covered on its sides with electrodes comprised of lanthanum strontium manganate (LSM) which in turn are coated with a layer of platinum to aid in the even distribution of the electrical current. An electrical current is passed through the electrodes to produce a voltage difference therebetween. The layers of YSZ and LSM are formed by a sol-gel process.

Abstract: A gas sensor element which may be employed in measuring the concentration of gas such O2, NOx, or CO. The gas sensor element consists of an electrochemical cell made up of a solid electrolyte body formed by a partially stabilized zirconia and a pair of electrodes disposed on the solid electrolyte body. The electrochemical cell is subjected to an aging treatment in which the dc current is applied to the electrodes at a given voltage to enhance the activation of the electrochemical cell.

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

Abstract: A method for detection of a bubble in a liquid which is placed in a measuring chamber and is in contact with a sensor for measuring the partial pressure of a particular gas in a liquid is provided. The method includes performing a first measurement of the partial pressure of the particular gas in the liquid at a first pressure in the measuring chamber. Next, the pressure in the measuring chamber is changed to a second pressure. A second measurement of the partial pressure of the gas in the liquid at the second pressure in the measuring chamber is performed. An expected result of the second measurement based on the first measurement and assuming that no bubbles are present in the measuring chamber during any of the measurements is provided. The actual result of the second measurement is compared with the expected result and a conclusion is drawn on the presence of a gas bubble in the liquid based on the comparison. An apparatus for measuring the content of a particular gas in a liquid is also provided.

Abstract: The invention relates to a method and a device for detecting leaks in the wall of a test object, container or similar, by measuring and evaluating changes that occur in a partial gas pressure. The invention aims to simplify the detection of leaks. To this end, changes that occur in partial pressures of oxygen are detected and evaluated using an oxygen sensor (4).

Abstract: The invention relates to an electrochemical gas sensor with a working electrode, which is designed as a thin-film electrode, and at least one counterelectrode, which are in electrical contact via an electrolyte. The electrochemical gas sensor is characterized in that the electrolyte is alkaline and preferably comprises a solution of a salt of a weak acid. The electrochemical gas sensor according to the invention may preferably be used to determine the oxygen concentration in a gas mixture.

Abstract: The presence of biological contaminants in a liquid coating composition is determined by measuring the carbon dioxide content of the atmosphere above the liquid and comparing the measured carbon dioxide level to a baseline carbon dioxide level. A biocide can be added to the liquid when the measured carbon dioxide level reaches a predetermined value to control the level of biological contaminants in the liquid coating composition.

Abstract: A CO sensor and a CO-concentration measurement method which enables accurate measurement of CO concentration irrespective of the hydrogen concentration of a gas under measurement. By applying a first predetermined voltage between first and second electrodes 7 and 8, hydrogen contained in a gas under measurement which has been introduced into a first measurement space 2 via a first diffusion-controlling section 1 dissociates, decomposes, or reacts with another element to generate protons. The thus-generated protons are transported from the first electrode 7 to the second electrode 8 via a first proton-conductive layer 5 or protons are transported from the second electrode 8 to the first electrode 7 via the first proton-conductive layer 5 (when the hydrogen concentration of the measurement gas is extremely low), so that the hydrogen concentration within the first measurement space 2 is controlled to a constant level.

Abstract: An electrochemical deposition and testing system consisting of individually addressable electrode arrays, a fully automated deposition head, and a parallel screening apparatus is described. The system is capable of synthesizing and screening millions of new compositions at an unprecedented rate.

Abstract: The sensor electrode has a sensing surface intended to contact a liquid medium for continuous measuring, in combination with a counter electrode and a reference electrode, of the hydrogen peroxide concentration over a concentration range from 0.005 mole/liter to 3 mole/liter, said sensor consisting of a carbon electrode having an open circuit potential between -65 and -85 mV, said open circuit potential being measured with respect to a Ag/AgCl/saturated Cl.sup.- reference electrode in an alkaline solution having a pH between 10.5 and 14, said solution containing hydrogen peroxide at a concentration of more than 0.5 mole/liter.

Abstract: There is provided a concentration sensor for measurement of concentrations of one or plural target substances in a system, with a detection electrode of conductive diamond. The measuring method with the concentration sensor involves measuring the reaction potentials of plural target substances in a sample containing and determining the concentrations of the plural substances by use of the difference between the resulting reaction potentials of the respective substances. The measuring method can also determine the concentration of a single substance in a sample containing one kind of target substance.

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 CO gas sensor according to the present invention includes a gas collecting container for collecting a measured gas therein; a detecting section provided within the gas collecting container and having at least a pair of electrodes positioned through electrolyte; and a voltage applying apparatus for applying voltage to the detecting section. One of the electrodes of the detecting section is a detection electrode having the capability of adsorbing at least one of hydrogenous gas and CO gas when a voltage is applied and then oxidizing it. By introducing a measured gas into a gas collecting container of the CO gas sensor and carrying out electrolysis according to a potential sweep method or a pulse method with the measured gas being in contact with the detecting section, a CO gas concentration in the measured gas can be measured based on an electrical current value obtained at the detecting section and changes of the electrical current with elapse of time.

Abstract: A method for calibrating an instrument for the analysis of blood gases which possesses ion-sensitive electrodes and gas-sensitive electrodes and is used for the determination, in a biological fluid, of the concentration of electrolytes and metabolites in solution, and of the pH, pO.sub.2 and pCO.sub.2, the said calibration being carried out with at least one buffered solution containing O.sub.2, a known or tonometer-measured amount of CO.sub.2 and known concentrations of the electrolytes and metabolites to be determined, in which calibration the pO.sub.2 titer is determined beforehand using atmospheric oxygen as reference.

Abstract: A new method which employs a mixed-valence cluster of M.sub.y.sup.z+ [Fe(II)(CN).sub.6 ] coated on an electrode surface to determine hydrogen peroxide concentration electrochemically is developed. M of the mixed-valence compound can be Co, Ni, Cr, Sc, V, Cu, Mn, Ag, Eu, Cd, Zn, Ru or Rh; z is the valence state of M; and y=4/z. In addition, this invention also reveals a new approach to determine a concentration of a hydrogen peroxide precursor, wherein a catalyst is immobilized in the matrix or on the surface of the mixed-valence compound on the electrode. In a typical biochemical system, the catalyst can be a glucose oxidase and blood sugar is catalyzed to form hydrogen peroxide.

Abstract: The CaCO.sub.3 content of a scrubbing suspension, especially for a desulfurizing apparatus for flue gas is measured by injecting an acid into a constant mass flow of the suspension circulating along a bypass and measuring the pH before and after such injection. The change in pH is compared with reference measurements and used as a basis for calculating the CaCO.sub.3 concentration.

Abstract: Methods are described for extending the service life of implantable sensors having a silver-containing anodic reference electrode maintained at a high impedance, at least one noble metal cathodic working electrode, and at least one noble metal anodic counter electrode maintained at a low impedance, particularly sensors for the in vivo detection of oxygen and/or glucose in bodily fluids. The methods described involve increasing the input impedance of the reference electrode up to a maximum for implanted circuitry and shielding said electrode, and/or alternating the operating roles of the reference and working electrodes, switching the working electrodes with counter electrodes in the circuit, reversing the polarities of the reference and working electrodes, and sequentially activating each electrode in a plurality of working and/or reference electrodes in the circuit.

Abstract: An electrode characterized by a layer of at least one polymer containing ferrocenylalkyl groups. The electrodes are useful in detecting hydrogen peroxide, organic (hydro)peroxides and lipid hydroperoxides.

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

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

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

Abstract: A carbon monoxide sensor in the form of a composite material including a transparent substrate, and a metal oxide layer provided over a surface of the substrate and containing nickel oxide and cobalt oxide in an amount providing an atomic ratio Ni/Co of 99:1 to 1:2. Carbon monoxide contained in an oxygen-containing gas is detected by a change in transmittace of light with a wave length of 350-1,500 nm passing through the composite material maintained at a temperature of 200.degree.-350.degree. C.

Abstract: A Clark-type gas detection apparatus includes a sensor electrode and a reference electrode exposed to an aqueous electrolyte solution which is isolated from a liquid medium surrounding the apparatus by a semi-permeable membrane. A preferred reference electrode for use in Clark-type apparatus comprises silver/silver chloride. Through the addition of an effective amount of a sulphate-based co-electrolyte to an electrolyte solution having a relatively low chloride ion content, it is possible to obtain an electrolyte solution having an ionic conductivity comparable to that of chloride-based electrolyte solutions currently used in Clark-type sensors while retaining sufficient chloride ion to drive the oxidation reaction near the reference electrode. The relatively low chloride ion content of the electrolyte solution of the present invention tends to suppress the dissolution of silver chloride from the reference electrode, and, consequently, the deposition of silver on the indicating electrode.

Abstract: The electrode of the present invention has metallic surface within a laser produced opening where the metallic surface extends into an electronic metallic conductive pathway and the pathway is covered for electric insulation by an encapsulant layer. The encapsulant layer around the metallic surface has the opening to allow the exposure of the metallic surface from the encapsulant layer. The metallic pathway and encapsulant are resident on a substrate, and are produced from layered circuitry. The electrochemical cell has the aforementioned electrode juxtaposed to another electrode. This electrode is part of the patterned metallic layer that is produced by layered circuitry. The electrode extends into an electronic metallic conductive pathway that is spaced apart and electronically insulated from the other pathway. The insulation can be supplied by a covering of encapsulant material that covers the pathway except does not cover the second electrode.

Abstract: Disclosed is an apparatus and method of equilibrating the dissolved gas composition of an aqueous fluid to reflect the predetermined gas composition contained in a gas equilibration reservoir. The equilibrated aqueous fluid can be used in a method of determining the concentration of a dissolved gas in a fluid sample. In one embodiment, the disclosed method is used to control the equilibrated gas composition of a calibrant fluid which, in turn, is used to measure the concentration of a dissolved gas, such as oxygen and carbon dioxide, in a sample fluid, such as whole blood.

Abstract: Disclosed is an apparatus and method of equilibrating the dissolved gas composition of an aqueous fluid to reflect the predetermined gas composition contained in a gas equilibration reservoir. The equilibrated aqueous fluid can be used in a method of determining the concentration of a dissolved gas in a fluid sample. In one embodiment, the disclosed method is used to control the equilibrated gas composition of a calibrant fluid which, in turn, is used to measure the concentration of a dissolved gas, such as oxygen and carbon dioxide, in a sample fluid, such as whole blood.

Abstract: The method of electrochemical determination of oxygen partial pressure in ionic melts includes providing a metal/metal oxide reference electrode consisting of an electrode body made of a metal selected from the group consisting of Mo, W, Hf, Nb and Ta and alloys thereof and a layer of an oxide of that metal on the electrode body; immersing a pure platinum electrode and the metal/metal oxide reference electrode in a glass melt; measuring a potential across the metal/metal oxide reference electrode and the pure platinum electrode immersed in the glass melt to obtain a measured potential characteristic of the oxygen partial pressure in the glass melt; obtaining a calibration curve relating the potential across said reference electrode and the pure platinum electrode to the oxygen partial pressure in the glass melt as a function of temperature; and obtaining the oxygen partial pressure in the glass melt from the measured potential and the calibration curve.

Abstract: A CO.sub.2 electrode can be calibrated with two PCO.sub.2 calibration standard solutions having known pH values and known bicarbonate ion source concentrations. An O.sub.2 electrode can be calibrated using air as one calibration standard and a solution containing an excess of an O.sub.2 depleting agent as a second calibration standard.

Abstract: An apparatus and method of electrochemically determining an oxygen concentration with an oxygen sensor that includes a working electrode. The working electrode has a potential profile that includes a first potential step (a first measuring potential), a second potential step (a second measuring potential) and a third potential step. A measuring period is provided at the first and second measuring potentials. The currents flowing at the first and second measuring potentials are calculated and integrated over time. One of the two measuring potentials may be varied, depending on the difference between the two integrals of the currents flowing at the first and second measuring potentials, until the two integrals equal 0. An oxygen concentration is then determined from the value of a potential which thereby results.

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

Abstract: A method for correcting an output from an electrochemical cell sensor, having an output responsive to a concentration of sensed species in a stream, a pressure and a temperature in an interactive non-linear relationship, comprising the steps of providing a pressure sensor for producing an output responsive to a pressure in proximity to the electrochemical sensor; providing a temperature sensor for producing an output responsive to a temperature of said electrochemical sensor; and processing the outputs of the electrochemical sensor, pressure sensor and temperature sensor in a neural network having an output function which compensates said electrochemical sensor for changes in pressure and temperature to indicate a concentration of the sensed species.

Abstract: The invention concerns a novel electrochemical sensor with which to measure gas concentrations and comprising a measuring electrode and an associated electrode containing a carbonaceous material with a specific surface of at least 40 m.sup.2 /g and with electrochemically active surface compounds which can be reversibly oxidized/reduced.

Abstract: An electrode system and method, including a measurement electrode, a reference electrode and a counterelectrode, for measuring hydrogen peroxide concentration in a solution. For the measurement electrode, an electrode made from titanium, zirconium, tantalum or niobium is used.

Abstract: A new electrochemical biosensor and method of its use. The electrochemical biosensor has a pair of electrodes consisting of a working electrode and a counter electrode made of the same electrically conducting materials. The counter electrode may be the same size or smaller than the working electrode. The biosensor includes a sample receiving portion wherein a portion of the electrode surfaces is covered by a reagent that includes a redox mediator and an enzyme. A fluid that contains an analyte is added to the sample receiving portion. A reaction involving the analyte, enzyme and redox mediator occurs. After this reaction is complete, an electrical potential difference is applied between the electrodes. Diffusion limited current is measured and correlated to the concentration of analyte in the fluid.

Abstract: Novel calibration solutions are provided which are useful, for example, with sensor assemblies used for analysis of CO.sub.2, and optionally, for concurrent analysis of O.sub.2, especially in combination infusion fluid delivery/blood chemistry analysis systems which include a sensor assembly with each of the assembly electrodes mounted in an electrode cavity in the assembly. The analysis system used in the practice of the present invention typically includes provision for delivering infusion fluid and measuring blood chemistry during reinfusion of the physiological fluid at approximately the same flow rates. The invention calibration solutions are useful for calibrating an array of sensors capable of simultaneously measuring a number of blood chemistry parameters, including the partial pressures (tensions) of carbon dioxide and oxygen, pH (hydrogen ion), sodium, potassium, ionized calcium, ionized magnesium, chloride, glucose, lactate and hematocrit, in body fluids.

Abstract: A biosensor for the detection and determination of the concentration of toxins by use of enzyme inhibition. Inhibition biosensors are affected by non-specific denaturation and substrate utilization which both result in a limited operational lifetime. These problems are mitigated by providing in an environment an enzyme which is oxidized by hydrogen peroxide the oxidized enzyme being reduced by an electron transfer agent, such as ferrocene, which is itself oxidized in the process. The electron transfer agent is capable of regeneration back to the reduced state and the extend of electron transfer regeneration gives a measure of enzyme inhibition by toxin. Electro-chemical technique allows for the generation of hydrogen peroxide from oxygen in aqueous media and the reduction of oxidized electron transfer agent. Immobilization of the enzyme to an electrode increases efficiency while potentially reducing denaturation. The biosensor can be used for the environmental determination of toxins like cyanide.

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