Abstract: An electrochemical gas sensor has at least one measuring electrode (5), a reference electrode (11) and an auxiliary electrode (7) in an electrolyte (3) and a diffusion membrane. The diffusion membrane (4) is formed from a polymer (Teflon® AF) containing bis-2,2-trifluoromethyl-4,5-difluoro-1,3-dioxol. The diffusion membrane (4) faces the ambient atmosphere.

Abstract: Electrochemical sensor for determining analyte in the presence of interferent, particularly carbon monoxide in the presence of hydrogen. An electrochemical cell is designed so that current flow resulting from reference electrode potential shift caused by interferent cancels out the current flow caused by interferent at the working electrode. Another electrochemical cell corrects for interferent concentration using the potential difference between a reference electrode in contact with interferent and a referent electrode not affected by inteferent.

Abstract: In an electrode system, particularly for electrochemical sensors, which comprises a working electrode, a counterelectrode and an electrolyte, the counterelectrode is constituted by a material containing an elementary carbon, whereby the long-term stability of the electrode system is considerably increased.

Abstract: A method for identifying an unknown gas using a diffusion limited sensor providing an electrical signal output when exposed to the gas. According to the method, a sensor is disposed in a chamber of fixed volume and having a gas input and gas output through which the gas flows, and the chamber is connected to a source of a known test gas of known concentration and known diffusion coefficient Dk. The input to the chamber is opened, causing the sensor to be exposed to the known test gas until a steady state electrical signal output from the sensor is obtained. The time Tk necessary for the sensor to attain a predetermined percentage of the steady state output is determined. The chamber is then connected to a source of unknown gas, and the input is opened, and time Tu necessary for the sensor to attain the predetermined percentage of a steady state output for the unknown gas is determined.

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

Abstract: 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: An electrochemical gas sensor including a sensor body having a cavity, an electrolyte in the cavity, an auxiliary electrode in contact with the electrolyte, a sensing electrode in contact with the electrolyte, and a blocking electrode in contact with the electrolyte. At least a portion of the blocking electrode is positioned intermediate the auxiliary electrode and the sensing electrode, and the blocking electrode reduces electroactive materials within the electrolyte. Also disclosed is a method for sensing a partial pressure of a target gas in a sample gas, the method including introducing the sample gas into a gas sensor, applying different potentials to the auxiliary electrode, sensing electrode and blocking electrode, reducing electroactive materials present in the electrolyte to prevent the electroactive materials from contacting the sensing electrode, and outputting an electrical signal from the gas sensor representative of the target gas partial pressure.

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

Abstract: A simple, reliable, and leak-proof electrochemical sensor for detection of toxic gases. The sensor comprises a housing having an electrochemical gas sensor cell with an electrolyte and first and second electrodes bonded to conductive plastic. Each of the first and second electrodes is a membrane formed from a fluoropolymer film having a layer adhered thereto of a catalyst-impregnated fluoropolymer. The layers of each of said first and second electrodes are bonded to conductive plastic, and are separated by an absorbent material having an electrolyte absorbed therein. The sensor is particularly intended for detection of carbon monoxide, but may be used to detect other gases.

Abstract: A method is disclosed for reliably calibrating a sensor used in diagnostic sensing of a predetermined parameter, e.g., CO.sub.2 partial pressure, O.sub.2 partial pressure, or pH, of a solution such as blood, the method compensating for expected variations over time in the value of the parameter in a calibration solution. The parameter of the calibration solution has a predetermined initial value, and the solution is initially located within a container that is configured to allow the value of that parameter to vary over time in a predetermined manner. Supplying the calibration solution to the sensor causes the sensor to produce a calibration solution signal, which is compared with a calculated value for the parameter based on its expected variation over time, to produce a calibration factor. Thereafter supplying the test fluid to the sensor causes the sensor produces a test fluid signal, and this test fluid signal then is adjusted in accordance with the calibration factor.

Abstract: A simple, reliable, and leak-proof three-electrode electrochemical sensor for detection of toxic gases. The sensor comprises a housing having an electrochemical gas sensor cell with an electrolyte and sensing, counter and reference electrodes bonded to conductive plastic. Each of the electrodes is a membrane formed from a fluoropolymer film having a layer adhered thereto of a fluoropolymer-impregnated catalyst. The layers of each of the electrodes are bonded to conductive plastic, and are separated by an absorbent material having an electrolyte absorbed therein. The sensor is particularly intended for detection of carbon monoxide, but may be used to detect other gases.

Abstract: An apparatus and method for sensing a concentration of oxygen in a flow of gas in a breathing circuit for a patient. A biasing voltage is provided across a zinc-air cell so that the zinc-air cell produces a current having a magnitude, wherein the magnitude of the current corresponds to the concentration of oxygen in the gas.

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

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

Abstract: A method 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: An electrochemical oxygen sensor with a measuring electrode, an atmospheric oxygen electrode as a reference electrode, and an auxiliary electrode in an electrolyte is improved such that a stable measured signal is obtained even during changes in the position of the measuring cell. To accomplish this, the auxiliary electrode is arranged in the vicinity of the measuring electrode and a protective electrode is provided between the measuring electrode and the auxiliary electrode.

Abstract: The present invention is a sensor having an electrode formed in electrical contact with a subminiature through hole. Because of the small diameter of the through hole, the material that fills the through hole and the through hole itself have an essentially negligible effect on the sensor. A relatively large number of sensors can be formed on the surface of the substrate within a relatively small fluid flowcell. Thus, more information can be attained using less analyte. The sensors of the present invention are preferably disposed on an alumina substrate which is essentially impervious to aqueous electrolytes and blood over long periods of storage in potentially corrosive environments.

Abstract: The present invention is directed to an electrochemical gas sensor network. The network includes a gas sensor for receiving a gas and for generating a target gas concentration signal. The gas sensor has an output terminal for providing an output signal that is a product of the target gas concentration signal and a first transfer function. The network also includes a compensation circuit having an input terminal connected to the output terminal of the gas sensor. The compensation circuit also has an output terminal which provides an output signal that is a product of the output signal from the gas sensor and a second transfer function. The second transfer function is approximately an inverse of the first transfer function. The present invention also contemplates a method of compensating for the attenuation of a high frequency component of an output signal of a gas sensor.

Abstract: The invention relates to an electrochemical sensor to determine the concentration of a gas to be quantified, comprising a housing, a measuring electrode comprising a catalystically active material which causes a reaction of the gas to be quantified, a counterelectrode comprising a carbon material, and a solid electrolyte in contact with the measuring electrode and the counterelectrode, wherein the solid electrolyte is prepared by swelling a solid matrix comprising an acrylate polymer with an electrolytic solution comprising at least one acid, and wherein the carbon material in the counterelectrode has a specific surface of at least 40 m.sup.2 /g and comprises reversibly oxidizable or reducible electrochemically active surface compounds.

Abstract: Accordingly, the present invention provides an electrochemical sensor comprising at least two electrochemically active electrodes, a non-aqueous electrolyte system and a diffusion barrier membrane through which the analyte in its gas phase is mobile but through which the non-aqueous electrolyte system is substantially immobile. The diffusion barrier membrane thus allows an analyte in its gas phase to enter the sensor, while substantially preventing the non-aqueous electrolyte from exiting the sensor.

Abstract: An electrochemical measuring cell for the simultaneous detection of different gas components in a gas sample, with a plurality of measuring electrodes (4, 5, 6) behind a diffusion barrier (7), with a common reference electrode (8) and counterelectrode (9) in an acid electrolyte, and with a potentiostatic evaluating circuit. Improvements in terms of service life for a sensor for the simultaneous detection of oxygen and carbon monoxide is provided with a reference electrode formed of a sintered mixture of metal and its metal oxide, preferably from the platinum group, the iridium group or gold and the potential of the CO-measuring electrode (5) relative to the reference electrode (8) is set at about 0 to 300 mV, and that of the O.sub.2 -measuring electrode (4) is set at a value between -300 and -800 mV.

Abstract: The present invention is an electronic wiring substrate for sensors formed over a subminiature through hole. Because of the small diameter of the through hole, the material that fills the through hole and the through hole itself have an essentially negligible effect on the sensor. Only a small amount of conductive material which fills each through hole is in contact with each associated electrode. Therefore, the purity of the electrode is not significantly altered by the conductive material coupled to the electrode. A relatively large number of sensors can be formed on the surface of the substrate within a relatively small fluid flowcell. Thus, more information can be attained using less blood. The substrate is essentially impervious to aqueous electrolytes and blood over long periods of storage in potentially corrosive environments.

Abstract: A method and apparatus for measuring the content of carbon dioxide in an aqueous medium, particularly boiler condensate from an electrical power plant. The apparatus comprises a container or housing defining an elongated vertical indicator chamber and a parallel vertical reference chamber which are connected by a generally horizontal passage. An indicator electrode and a reference electrode are mounted in the indicator chamber and reference chamber, respectively. The lower end of the indicator chamber is open, and the open end is enclosed by a membrane of microporous polytetrafluoroethylene. The lower end of the indicator electrode is flat or planar and is located in close proximity to the inner face of the membrane. A filling liquid consisting of pure water is located within both chambers in contact with the respective electrodes. The apparatus can be mounted in a condensate bleed line of a power plant. The condensate in the bleed line is in initially adjusted in pH to a value of about 4.

Abstract: An oxygen sensor based on a metal-air cell, typically a commercially available zinc-air battery of the type used in hearing aids. The cell, which admits oxygen to generate electric current at its cathode is disposed in a mechanical housing which restricts the flow of oxygen to the cell, and is connected to an electrical circuit which provides a variable resistance load, the load increasing as current flow through the circuit decreases, to prevent hydrogen evolution at the cathode. Current flow through the cell is measured, and is proportional to oxygen concentration.

Abstract: An electrochemical sensor is provided on a substrate whereby a precious metal layer is arranged in an inner region under an electrolyte layer that is surrounded by a polyimide structure. A hydrophobic layer is surrounded by an outer polyimide structure and further is located on top of the electrolyte layer and extends laterally beyond the electrolyte layer. A lead for electrical connection of the precious metal layer extends under the hydrophobic layer laterally from the electrolyte layer is sealed from the hydrophobic layer by a protective layer. The protective layer prevents the penetration of analysis fluid into the gap between the hydrophobic layer and the surrounding polyimide structure into the inner region of the sensor. The material of the protective layer is preferably a double layer of PECVD oxide and PECVD nitride.

Abstract: The invention is directed to an electrochemical measuring cell to detect different gas components. The measuring cell includes several measuring electrodes (12, 15, 18) and a counter electrode 30 in an aqueous electrolyte 3. The measuring cell is improved with respect to the selectivity of the detection of the different gaseous components. A step-like offset 34 is provided between one of the measuring electrodes 12 and another measuring electrode 15.

Abstract: An electrochemical gas sensor having a temperature sensitive element such as a thermistor arranged within the gas sensor in a temperature insulative fashion for preventing any variations in the temperature of the applied gases to be sensed to be immediately conveyed to the temperature sensitive element thereby providing accurate temperature compensation signals to be combined with the generated sensor electrical output signals. The temperature sensitive element or thermistor is mounted in a heat sink to the expansion membrane of the gas sensor to be responsive only to changes in the temperature variations imparted by the sensor electrolyte and not by the variations in the temperature of the gas sensor body and associated elements thereby providing correct temperature compensation signals without error producing time delays.

Abstract: An electrochemical-enzymatic sensor for the determination of substances, in particular glucose, in body fluids, which possesses a good long-term stability, includes: a sensor electrode of electrocatalytically inactive carbon, a counterelectrode, a reference electrode, an enzyme-containing layer located before the sensor electrode, and a diaphragm of biocompatible, hydrophilic, oxygen-permeable material covering the enzyme layer toward the body fluid and retaining the enzyme.

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

Abstract: A polarographic sensor device to determine the partial pressure of a gas in a sample medium is disclosed. The device comprises a) a substantially hydroscopic electrolyte composition joining a pair of spaced apart electrodes, one of the pair of electrodes being a sensing electrode; b) a membrane permeable to gas but impermeable to the electrolyte, the membrane having a front section for separating the electrodes and the electrolyte from the sample medium; and c) a fastener comprising a sleeve having a body portion and a lip, the body portion retaining the fastener and a side section of the membrane, and the lip retaining a portion of the front section of the membrane and holding substantially the entire front section in a spaced apart relationship from the sensing electrode.

Abstract: A cell block for housing a sensor cell within a gas analyzer is mounted on the front panel of the analyzer, holding the sensor within a horizontal plane. The cell block is made of inexpensive and non-permeable material such as aluminum which is brazed and anodized. Entry and exit of sample gas is unique as is sample gas exposure to the sensor. Dead space is minimized and response time is improved. An insulated thermister in the cell block maintains accuracy over a wide range of temperatures. The device is RFI and EMI protected.

Abstract: The invention is directed to an electrochemical measuring cell 1 for detecting different gas components. The electrochemical measuring cell includes several measuring electrodes (8, 12, 13), a common counter electrode 21 and a common reference electrode 20 in an aqueous electrolyte 3. The measuring electrodes each include a diffusion membrane (7, 11) and individual diaphragms (9, 14) limiting the inflow of gas to the individual measuring electrodes (8, 12). The diffusion membranes (7, 11) cover the measuring electrodes (8, 12, 13). The measuring cell 1 is so improved that the selectivity of the detection of different gas components is improved. An electrolyte barrier 19 is provided at least between one of the measuring electrodes 8 and the remaining measuring electrodes (12, 13). The electrolyte barrier 19 prevents lateral diffusion within the diffusion membrane (7, 11).

Abstract: Method and device for determining the concentration of one or more gases, e.g. O.sub.2 or CO.sub.2 or an anaesthetic gas, in a fluid e.g. a body fluid or a gas mixture. A membrane (12) permeable to the gases retains a solvent (22) e.g. dimethylsulphoxide. In contact with the solvent is a working electrode (24) of a surface area preferably less than 10 .mu.m.sup.2. The potential of the working electrode is sept, over a range to reduce each of the one or more gases, and at a rate to minimize cross-reactions between gases and their reduction products.

Abstract: A solid state, multi-use electrochemical sensor having an electrically nonconductive substrate, a working electrode, and a semi-permeable membrane covering the working electrode. The working electrode includes an electrically conductive material adhered to a portion of the substrate. A first portion of the conductive material is covered with an electrically insulating dielectric coating, and a second portion of the conductive material is covered with an active layer. The active layer includes a catalytically active quantity of an enzyme carried by platinized carbon powder particles, which are distributed throughout the active layer. A sensor package for incorporating a sensor is provided.

Abstract: The present invention provides a low-cost alternative to currently available electrochemical sensors. In general, the present invention provides an electrochemical sensor for the detection of an analyte comprising a first metallic housing member and a second metallic housing member. The first metallic housing member and the second metallic housing member are brought together in sealed connection to create a sealed enclosure therebetween. Contained within the enclosure are a first electrode, at which the analyte reacts, and a second electrode, at which a reaction complimentary to the reaction of the analyte at the first electrode takes place. An acidic electrolyte is also contained within the enclosure of the first metallic housing member and the second metallic housing member.

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: An electrode sensor which may be used to specifically and quantitatively measure nitric oxide is provided, as well as a method of preparing and using such an electrode sensor to measure nitric oxide concentration in solution. A nitric oxide (NO) microsensor based on catalytic oxidation of NO comprises a thermally-sharpened carbon fiber with a tip diameter of about 0.5-0.7 .mu.m coated with several layers of p-type semiconducting polymeric porphyrin and cationic exchanger deposited thereon. The microsensor, which can be operated in either the amperometric, voltammetric or coulometric mode utilizing a two or three electrode system, is characterized by a linear response up to about 300 .mu.M, a response time better than 10 msec and a detection limit of about 10 nM. The sensor of the present invention also discriminates against nitrite, the most problematic interferant in NO measurements.

Abstract: A planar, solid-state electrochemical oxygen sensor having a substrate, conductive strips deposited on the substrate, and a dielectric layer insulating portions of the conductive strips except those portions which define a working electrode and at least one second electrode. The working electrode may be defined by an open printed region of the dielectric, or by a needle-punched or laser-burned hole or opening in the dielectric which exposes a small region of one of the conductive strips. A solid electrolyte contacting the electrodes is covered by a semipermeable membrane which may comprise an acrylonitrile butadiene copolymer or an acrylate-based copolymer. A sample chamber is defined by the membrane, a cover member, and a gasket therebetween, and has a volume of from about 1 to about 2 .mu.m. The gasket is formulated from the highly cross-linked polymerization product of epichlorohydrin. All sensor components are selected such that a sensor operable for at least 2 days under normal conditions is produced.

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: A method of manufacturing a gas-permeable membrane for an amperometric gas electrode comprising demetallizing areas of a metallized film to obtain a regular array of gas-permeable micropores.

Abstract: A planar bicarbonate sensor has been discovered that has a dried residue internal electrolyte layer comprising a bicarbonate source and a halide salt of potassium, lithium, or sodium. The flow-through sensor is capable of providing bicarbonate level of a liquid sample, and when coupled with a pH sensor, may be used to determine the partial carbon dioxide level in the sample. The sensor provides many commercially desirable characteristics including an adequate lifetime, good response time, and good stability upon first usage.

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: A probe is disclosed for use with a dissolved gas meter, which is capable of measuring the concentration of dissolved gas in a fluid by measuring the permeation of gas through a membrane into an electrolyte solution. The probe includes an inner member, preferably tubular, disposed inside an outer member, preferably tubular, each tubular member having an open top end. Preferably, the inner tubular member and the outer tubular member are coaxially located such that an annular space is formed between the inner and outer tubular member. The probe further includes a plurality of electrodes operably connected inside the probe to the meter. A counter electrode extends into the central chamber of the inner tubular member, along the central axis. A working electrode is wrapped around the outer tubular member. A reference electrode is wrapped around the inner tubular member.