Abstract: The present invention pertains to an apparatus and a means of constructing a pH sensor that can detect changes in pH levels of humidified gases and liquid samples. When electronically connected to a computerized or analog display means, sensitive quantitative measurements can be obtained. Given the construction of current pH devices available today, there is a need in the field for a novel, miniaturized, self-condensing pH probe that can be used in fluid or humidified gases.

Abstract: The present invention describes a new electrochemical biosensor comprising (i) a biocatalyst producing a pH change when interacting with the analyte to be determined and (ii) a compound exhibiting different redox properties both in its protonated and non-protonated forms (pH-sensitive redox compound). The elements described above are integrated in a biosensor system composed of a working electrode and a reference electrode connected to an ammeter. When the analyte is present, the system produces a current change that is proportional to the concentration of the analyte. The biosensors described herein can be used in the accurate detection of a wide range of analytes. They can be used in diagnostics, industrial processes, food and feed quality control, biotechnology, pharmaceutical industry, environmental monitoring and so on.

Abstract: An automatable measuring, cleaning and calibrating device for pH-electrodes or electrodes for measuring redox potentials, specifically in process engineering, having an electrode armature which keeps the measuring electrode in an operating position or in a maintenance position, whereby the electrode is retained in the maintenance position in a rinsing chamber in which a cleaning and calibration procedure can be performed. The device has a pump device to supply cleaning fluid and calibration solutions to the rinsing chamber over a delivery line connecting the pump device and the rinsing chamber. In order to configure the device more compactly, the pump device includes several feeds on its intake side, and a device is furnished to selectively activate a particular feed, and the media (cleaning fluid, calibration solution, etc.) brought selectively over the particular feeds to the pump device reach the rinsing chamber over the common delivery line.

Abstract: An inexpensive, high-performance pH sensor measure the surface of a solid substance in a simple manner, comprising an ion sensing part 2 which responds to pH, a reference electrode 3, a gel-form ion permeable substance 10, which has a predetermined pH value and covers the ion sensing part 2 and reference electrode 3, and a cover member 9, which houses the ion permeable substance 10 and has an opening 9a formed at a position near the abovementioned ion sensing part 2.

Abstract: A pH electrode having a pH-sensitive region on an electrically conductive support, said pH-sensitive region comprising a mixture of between 50% and 85% of the total mixture by weight of particles of a Group VA or Group VIII metal incorporated in, or applied to, a polymer substrate of a non-shrinking plastic selected from polyimides, the polymer substrate having a resistivity of 10 to 100 Kohms/square the metal particles including antimony particles and, when said particles are incorporated into said resistive polymer substrate, having said pH-sensitive region abraded to expose said particles.

Abstract: A method and apparatus estimate hydrogen concentration in a reformate stream produced by a fuel processor of a fuel cell. A sensor measures carbon monoxide, carbon dioxide, and water in the reformate stream. A fuel meter controls fuel input to the fuel processor. An air meter controls air input to the fuel processor. A water meter controls water input to the fuel processor. A transport delay estimator recursively estimates transport delay of the fuel processor. A hydrogen estimator associated with the transport delay estimator, the air, water and fuel meters, and the sensor estimates hydrogen concentration in the reformate stream. The hydrogen estimator includes a fuel processor model that is adjusted using the estimated transport delay. The carbon monoxide, the carbon dioxide and the water are measured using a nondispersive infrared (NDIR) sensor.

Abstract: A potentiometric sensor device for measuring pH value is provided, which sensor device has two electrodes situated on a substrate and applied with the aid of thick-film technology. The two electrodes form an interdigital comb structure on the substrate.

Abstract: A galvanic probe comprises a sensor electrode and a reference electrode. The sensor electrode has an exposed surface that comprises a noble metal or antimony or bismuth, and, optionally, an oxide or hydroxide thereof. The reference electrode is spaced apart from the sensor electrode and has an exposed surface that comprises zinc or magnesium, and, optionally, an oxide or hydroxide thereof. The probe may be incorporated into a device for controlling the pH and/or ORP of a fluid in a vessel to a desired pH and/or ORP level, incorporated into methods for measuring the pH and/or ORP of a fluid, or used as a galvanic cell.

Abstract: Disclosed is a microchip-based differential-type potentiometric oxygen gas sensor, which comprises a working electrode and a reference electrode. The working electrode is composed of a cobalt-plated electrode, a buffered hydrogel, and an ion sensitive gas permeable membrane while the reference electrode is composed of an oxygen non-sensitive silver chloride electrode and the same ion-selective gas-permeable membrane of working electrode. By taking advantage of the corrosion potential, the microchip-based oxygen gas sensor can accurately and quickly detect the content of dissolved oxygen in a sample solution. With this structure, the oxygen gas sensor is applied to a microchip-based all potentiometric multi-sensor capable of detecting two or more ions and gas species on a single chip.

Abstract: A galvanic probe comprises a sensor electrode and a reference electrode. The sensor electrode has an exposed surface that comprises a noble metal or antimony or bismuth, and, optionally, an oxide or hydroxide thereof. The reference electrode is spaced apart from the sensor electrode and has an exposed surface that comprises zinc or magnesium, and, optionally, an oxide or hydroxide thereof. The probe may be incorporated into a device for controlling the pH and/or ORP of a fluid in a vessel to a desired pH and/or ORP level, incorporated into methods for measuring the pH and/or ORP of a fluid, or used as a galvanic cell.

Abstract: A pH sensor including a reference electrode, a measuring electrode operatively connected to said reference electrode, a fluid conduit for containing an electrolyte in electrolytic contact with said reference electrode, a reservoir in fluid communication with said fluid conduit, a reference junction encasing said reference electrode, and an external junction, wherein said electrolyte comprises a viscous silica suspension to maintain a flow of said electrolyte from said reservoir to reduce inward diffusion through said external junction.

Abstract: Systems and methods are provided herein for improving the selectivity and productivity of sensors via digital signal processing techniques. According to one illustrative embodiment, in an electrochemical method for monitoring of a select analyte in a mixed sample with an interfering analyte, an improvement is provided that includes applying a large amplitude potential stimulus waveform to the sample to generate a nonlinear current signal; and resolving a signal contribution from the select analyte in the generated signal by a vector projection method with an analyte vector comprising a plurality of real and imaginary parts of one or more Fourier coefficients at one or more frequencies of a reference current signal for the select analyte.

Abstract: An electrochemical sensor includes an electrochemically active sensor layer (sensor spot), which is applied by means of thick film techniques in at least one region of an electrically insulating, planar substrate, the surface of the sensor layer being brought into contact in a measuring area with the aqueous sample to be determined. At least one conductive path for signal pick-up is also applied on the substrate by means of thick film techniques. The sensor layer contains at least one oxide of metal from subgroups 7 and 8 wof the Periodic Table as sensor component. The contact between the electrochemically active sensor layer and the conductor is effected via an electrically conductive bridge layer which extends from the measuring area in a direction essentially parallel to the surface of the substrate. The bridge layer consists of corrosion-resistant material.

Abstract: Disclosed are combination glass pH electrodes, the standard potential of which is stabilized by means one or more of the following structural modifications:

Abstract: A chemical sensor (1) for selectively detecting an analyte in a solution as described. The sensor comprises a flow-through chamber (2), a selective membrane (3), a transducer means (4), an inlet (5) for a liquid flow containing a recognition element, and an outlet (6). There is also described a method of selectively detecting an analyte in a solution, wherein a recognition element is contacted with the solution containing the analyte via a selective membrane, said contact resulting in a response detectable by transducer means. The recognition element is injected into a flow, the flow is passed into a flow-through chamber comprising a transducer means and the selective membrane, where it is contacted with the analyte passing from the solution outside the selective membrane, whereby the recognition element and the analyte interact to provide a signal which is detected by the transducer means.

Abstract: A reference junction for a reference half-cell, the reference junction including an ion-barrier membrane and being sized and shaped for removable receipt within a receptacle of a reference half-cell housing. The reference junction may be included in an electrochemical potential measurement sensor for use in making pH, other selective ion activity, oxidation-reduction potential, and other electrochemical potential measurements.

Abstract: A reference electrode (1) for electrochemical measurements includes a metallic palladium-containing electrode component (3) which is covered by a layer (4) formed of or containing a palladium compound poorly soluble in aqueous media. Positioned on layer (4) is a reference electrolyte (5) which contains anions of this palladium compound in dissolved form (FIG. 4).

Abstract: A flexible pH probe device is provided for use in hot water and other high temperature environments up to about 590° F. The pH probe includes a flexible, inert tubular probe member, an oxygen anion conducting, solid state electrolyte plug located at the distal end of the tubular member, oxide powder disposed at the distal end of the tubular member; a metal wire extending along the tubular member and having a distal end in contact with the oxide powder so as to form therewith an internal reference electrode; and a compression fitting forming a pressure boundary seal around a portion of the tubular member remote from the distal end thereof. Preferably, the tubular member is made of polytetrafluoroethylene, and the solid state electrolyte plug is made of stabilized zirconia. The flexibility of the probe member enables placement of the electrode into the area of interest, including around corners, into confined areas and the like.

Abstract: In a pair of electrodes where a potential difference is changed in accordance with acidity or basicity of oil, a reference electrode is made of cobalt or a cobalt alloy, and a sensitive electrode is made of tungsten or a tungsten alloy. The sensitive electrode is used in combination with the reference electrode. Accordingly, it is possible to provide a pair of electrodes for detecting the acidity or the basicity of the oil which use a novel electrode material not hazardous to the environment and at the same time, suited for use in a semiconductor fabrication technique.

Abstract: The present invention is an improved yttria-stabilized zirconia electrode having a ceramic tube (12). The electrode is improved by replacing the method of sealing the electrode with an epoxy seal (24) and filling the tube with a ceramic glue (42) without completely filling the tube. The ceramic glue is added in a small amount and the ceramic glue is heated in the tube before a next small amount of ceramic glue is added, until the final amount of ceramic glue is added and heated. Also, an area of cover on a wire (18) in an area between a top of the ceramic glue and a top of the tube is partially removed. A sealing glue above the top of the ceramic glue that adheres to the wire at the removed area of the cover, adheres to the tube and seals the top of the tube. Finally, an outside portion of the wire which extends beyond the top of the tube is gripped with a CONAX fitting (26), instead of the fitting gripping the tube.

Abstract: An electrochemical sensor for detecting the presence and amount of acetate in cell culture and fermentation media. The electrochemical sensor has a pH electrode, an internal reference electrode, a special high-tensile strength gas permeable membrane, and internal reference electrolyte such that acetate concentration can be measured using a pretreatment buffer having a pH of about 5.5.

Abstract: The invention provides a sensor with a reference electrode and a flowing electrolyte which is particularly useful for measuring the ion concentration of a process solution. The invention includes a sensor having a pressurized reservoir which provides flow of an electrolyte, a non-metallic solution ground and a resistance temperature device bonded to a non-metallic solution ground. The invention provides sensors with greater accuracy and stability by minimizing or eliminating ingress of contaminants from a process solution through the external junction of the sensor.

Abstract: A test method and apparatus for determining the content of carboxylic acid-based corrosion inhibitors in a coolant or heat exchange fluid. The amount of acidic reagent added to the coolant or fluid between two pH equilibrium points is measured to determine the amount of inhibitors. The refractive index can be measured to determine the amount of freezing point depressant.

Abstract: A pH sensor is provided capable of readily determining the pH of a solution of a small amount. The pH sensor includes a semiconductor substrate, an oxide film provided on the semiconductor substrate, a solution storage part for holding a solution on the oxide film, and an electrode to be in contact with the solution in a vicinity of the oxide film. To determine the pH of a solution, a capacitance-voltage characteristic is initially monitored by the sensor between the electrode in contact with the solution and another electrode provided on the back surface of the semiconductor. Then the pH of the solution is derived from a flat band voltage which is obtained based on the capacitance-voltage characteristic.

Abstract: A pH electrode having a pH-sensitive region on an electrically conductive support, said pH-sensitive region comprising

Abstract: The present invention is drawn generally to an improved electrochemical sensor. The reference cell within the sensor can be a salt bridge comprising at least two chambers for containing an electrolyte fluid, preferably containing a semipermeable plug impregnated with an electrolyte, an essentially fluid impermeable plug for separating the at least two chambers, and a narrow opening through the plug providing a non-axial flow path for ionic communication between the at least two chambers when the electrolyte fluid is present.

Abstract: A sensor for measuring pH of a solution includes a housing with an exterior surface for exposure to the solution. A measuring glass electrode within a tubular circuit ground electrode extends through the exterior surface. A reference glass electrode is received in a neutral pH solution in the housing and is coupled by a salt bridge to the exterior surface. An electric circuit within the housing has a first preamplifier connected by a first conductor to the measuring glass electrode and has a second preamplifier connected by a second conductor to the reference glass electrode. The first and second conductors have substantially equal lengths so that ambient electrical noise equally affects signals from the electrodes. The electrical cable that carries output signals from the electric circuit passes through a ferrite sleeve which inhibits high frequency electric noise that is induced in the cable from reaching the electric circuit.

Abstract: The present invention provides a means to substantially decrease the pH bias that is commonly observed with pH data obtained using ion selective electrode (ISE) containing instruments that have a solvent polymeric membrane based ISE pH electrode. The pH bias is reduced by utilizing the discovery that the presence of protein in a liquid sample induces an apparent interference with the pH value.

Abstract: There is provided a microchip-based differential-type carbon dioxide gas sensor for detecting dissolved carbon dioxide levels. It functions with at least one working electrode composed of an unbuffered hydrogel membrane containing a certain amount of sodium bicarbonate and a pH-sensitive gas-permeable membrane; and a reference electrode composed of a buffered hydrogel membrane and a pH-sensitive gas-permeable membrane. The unbuffered hydrogel membrane contains carbonic anhydrase, which reduces the time period for the hydration of carbon dioxide, thereby allowing the quick measurement of the level of carbon dioxide. In addition to being significantly improved in stabilization, sensing, and recovering time periods, the differential-type carbon dioxide gas sensor can be fabricated in small sizes and quickly measure levels of carbon dioxide dissolved in sample solution.

Abstract: An apparatus is disclosed for electrolytic desilvering of photographic processing solutions, more particularly fixing solutions or bleach-fixing solutions, comprising an electrolysis unit equiped with a monitoring system comprising a cathode, an anode and a reference electrode, characterized in that said reference electrode is a pH sensitive electrode. The desilvering is preferably performed under potentiostatic conditions. Whe using a pH sensitive reference electrode the cathodic plating potential is automatically corrected for pH changes. A preferred pH sensitive electrode is a glass electrode.

Abstract: A detector assembly for detecting a plurality of different properties at the same location at the same time is provided by integrating onto a single semiconductor substrate a first detector unit for measuring a first property and a second detector unit for measuring a second property. The first and second detector units can share, for example, a common element, such as a sensor device that can provide electrical output signals representative of, respectively, the first property and the second property. The common element can include a diaphragm with a pyroelectric element to provide a measurement of temperature and pressure.

Abstract: The apparatus of the invention includes a flow chamber having an inlet, an outlet, and a removable cover. The cover includes fittings for mounting a reference electrode assembly, a measuring electrode assembly, and a combined counter electrode/thermistor probe. According to the one illustrative embodiment invention, the flow chamber is substantially cylindrical with the inlet located near the bottom of the chamber and the outlet located near the top of the chamber. The axes of the inlet and outlet lie in the same plane as and are parallel to a diameter of the chamber. The inner diameter of the inlet is reduced to approximately ⅛″ so that the velocity of water entering the chamber is increased. The inner diameter of the outlet is approximately ¼″ so that the velocity of water exiting the chamber is less than the velocity of water entering the chamber.

Abstract: Electrochemical cell having a porous substrate and a first and a second electrodes separated by an ion diffusion inhibiting partition is disclosed. The ion diffusion inhibiting partition between the two electrodes is defined by compressing the substrate and/or blocking pores of the substrate so as to inhibit but not entirely block ion diffusion between the two electrodes.

Abstract: An acidity measuring apparatus includes a measuring container for accommodating an electrolyte solution including one of a 1,2-benzoquinone derivative and a 1,4-benzoquinone derivative, an organic solvent, an electrolyte and an acid-containing subject for measurement; a working electrode, a counter electrode and a reference electrode section provided in the measuring container and immersed in the electrolyte solution; and a control section for sweeping a potential of the working electrode within a prescribed range and for detecting a value of a pre-peak current generated by the acid and flowing between the working electrode and the counter electrode.

Abstract: A pH electrode arrangement comprises an inner wire electrode of silver sulfide, and a fill solution comprising a solution of sodium thiosulphate, a buffer, and an antioxidant. The arrangement has a fast response to a change in temperature, a half cell near .+-.500 mV, and an isopotential point near 7 pH.

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: Tests for elevated pH and volatile amines in aqueous fluids are disclosed, including tests useful in the diagnosis of bacterial vaginosis and in other biological conditions. By using formulated indicators and indicators held in matrices that are permeable to gas but not to liquid, the tests provide clear and sharp transitions detectable by visual or machine-readable means rather than by subjective judgments such as small gradations in color or olfactory determinations. The tests lend themselves readily to iconic readouts of the test indications and to the inclusion of positive and negative controls.

Abstract: Described is a combination, PVC-membrane, Ion-Selective Electrode (ISE) with a replaceable sensing module and a single-junction, sleeve-type reference electrode. pH and ion-selective electrodes (ISEs) in the "Combination" configuration, i.e., single probes containing both the sensing and reference half-cells, are more convenient, more economical, and can be used to analyze smaller samples than an equivalent pair of separate half-cell electrodes.

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: The invention pertains to linear electrochemical functional elements which consist of strip-shaped ion-exchange membranes (IEMs) and/or hydrogen-diffusion electrodes accessible at the ends which are enclosed on all sides in an insulating manner by a jacket of a solid material. The invention describes the structure, production and use of the functional elements in electrochemical measuring techniques.

Abstract: A method of producing a medium-tight connection between interior and exterior concentrically-arranged glass tubes includes the steps of providing a longitudinally extending electrical conductor strip between the interior and exterior tubes, forming a bulge extending radially outwardly from the interior tube by heating the tube, inserting the interior tube into the exterior tube, and forming a constriction in the exterior tube which extends radially inwardly and connects with the radially outwardly extending bulge to form a closure area, whereby the conductor strip passes through the closure area. An electrochemical sensor for measuring pH values or redox potentials formed according to this method includes an elongated housing which contains an interior chamber defined by the interior tube, a glass membrane cap, and a closure member, and an annular exterior chamber defined by the interior and exterior tubes.

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: Analyzers determine the concentration of a test substance by measuring the change of pH in a sample liquid after reaction of the test substance with a reactant. The analyzers have a tube connected between first and second microcapillary pH electrodes. In a first embodiment, the tube functions as a reaction chamber by having a reactant immobilized on a wall of the tubing or confined within the tubing. In a second embodiment, the reactant and test substance are mixed upstream relative to the first and second microcapillary pH electrodes, with the tubing serving as a delay circuit for a kinetic measurement. Output signals of the microcapillary flow-through electrodes are used to determine a change in pH, the change in pH being indicative of the concentration of the test substance.

Abstract: A sensor for measuring pH and conductivity for liquids is disclosed. The sensor includes a housing having a pH cell and a conductivity cell. A pH fluid flow path is defined between a pH cell fluid inlet and pH cell fluid outlet. An aperture within the pH cell is adapted to receive an electronic pH probe therein. The aperture is configured to position an end of the pH probe having a pH sensing area therein and juxtaposition to the pH fluid flow path so that fluid flowing within the flow path is exposed to the pH sensing area of the electronic pH sensor. A conductivity cell is adapted for placement of a conductivity sensor therein. The conductivity sensor is disposed between a conductivity cell fluid inlet and conductivity cell fluid outlet so that fluid flowing therethrough contacts the conductivity sensor.

Abstract: An electrochemical sensor capable of detecting and quantifying urea in fluids resulting from hemodialysis procedures. The sensor is based upon measurement of the pH change produced in an aqueous environment by the products of the enzyme-catalyzed hydrolysis of urea. The sensor may be fabricated using methods amenable to mass fabrication, resulting in low-cost sensors and thus providing the potential for disposable use. In a typical application, the sensor could be used in treatment centers, in conjunction with an appropriate electronics/computer system, in order to determine the hemodialysis endpoint. The sensor can also be utilized to allow at-home testing to determine if dialysis was necessary. Such a home monitor is similar, in principle, to devices used for blood glucose testing by diabetics, and would require a blood droplet sample by using a finger prick.

Abstract: The invention relates to a sensor electrode connected to a card module that can be received within an industry standard plug-in receptacle of a selected computer to enable a combination capable of very exhaustive data detection, processing, storage and the like for whatever the selected data sensor and particular card module.

Abstract: An improved active electrode for use in planar sensors has been discovered, the electrode prepared by a process comprising combining a base component with a metal paste and heating the paste in the presence of air for a time sufficient to oxidize a portion of the electrode to produce the metal/metal oxide electrode. The electrodes may be incorporated into various planar sensor formats, particularly pH and CO.sub.2 sensors.

Abstract: A pH-measuring method and device for monitoring and then correcting for electrode drift is provided. The device includes a pH-measuring electrode and more than one reference electrode. During operation, the pH-measuring device is place in contact with a sample. The pH value measured at each electrode pair is due to the electrical potential difference between the pH electrode and the reference electrode. The maximum and minimum pH values are determined, and then the remaining pH values are averaged together to generate an overall average pH. The maximum and minimum pH values are subtracted from the average pH to generate a difference which is then compared to a user-defined drift level to determine if a particular electrode is deficient. The pH values from deficient electrodes are not considered when the overall pH of the sample is determined.

Abstract: A device for measuring the parameters of a sample of fluid comprising exchangeable containers for calibrating fluids and an oxygen electrode. The device comprising a measuring chamber having at least two measuring channels with measuring electrodes for determining the acid-base equilibrium parallel introduced into the measuring channel of the device and connected with a common electronic system. The exchangeable containers for calibrating fluids each comprising an elastic, impermeable container for gases with an elastic joint for ensuring tightness of the connection between the container and a device. The oxygen electrode comprising an oxygen electrode of a Clark's electrode system with an anode made of an element selected from the VIB group of the periodic system of chemical elements.

Abstract: An apparatus for adjusting the pH of an electrolytically dissociated process stream is disclosed. The apparatus includes a matrix of pH adjusting chemical and an erosion rate modifier. The pH adjusting chemical is preferably citric acid and the erosion rate modifier is preferably polyethylene glycol. A porous material such as a sponge may be interposed between the matrix and the process stream to further modify the erosion rate.