Abstract: A flowing junction reference electrode comprising a liquid junction member matched with a filter. The junction member and the filter are situated between a reference electrolyte solution and a sample solution. An array of nanochannels spans the junction member and provides fluid communication between the electrolyte solution and the sample solution. The filter is configured to allow a greater flux of electrolyte than that associated with the junction member. Preferably, the number of pores is greater than the number of nanochannels. The filter is preferably configured to have pores with an inner diameter that is the same or less than the inner diameter of the nanochannels. In some embodiment, the resistance of the filter is made lower relative to the resistance of the junction member by selecting suitable length, number, and inner diameter size for the pores of the filter relative to the nanochannels of the junction member.

Abstract: A reference electrode includes a conductive substrate having a first surface and an ionically insulating, hydrophobic layer adjacent to the first surface having a plurality of non-selective ion exchange sites.

Abstract: The present invention provides an improved ion measuring composite electrode, measuring instrument incorporating the composite electrode, and a manufacturing method for forming a preform of a composite double glass pipe for forming the ion measuring composite electrode. A hollow inner pipe and a hollow outer pipe are axially aligned with an elongated member having liquid absorption capacity. The inner pipe is welded to the outer pipe to form an annular space there between for receiving reference electrode liquid. The elongated member insures electrical conductivity even in the presence of air bubbles so that the measuring instrument is operatable and an appropriate weld can be easily manufactured to improve productivity.

Abstract: Disclosed are combination glass pH electrodes, the standard potential of which is stabilized by means one or more of the following structural modifications: (a) incorporating a noble metal internal element in the pH half-cell; (b) incorporating a noble metal internal element in the reference half-cell; (c) incorporating an internal pH bulb electrolyte with stable pH and oxidation-reduction potential; (d) incorporating an homogenous reference electrolyte with stable oxidation-reduction potential and equitransferent salt; (e) incorporating a liquid junction composed of a porous, inert material; (f) incorporating a reference electrolyte compartment vent; (g) incorporating a storage sleeve, with or without an absorbent medium located therein.

Abstract: A reference electrode traps silver ions and chloro complex ions leaching to an internal filling solution so that the blocking of the liquid junction can be prevented. A silver/silver chloride electrode can be provided as an internal electrode in an internal filling solution; and a tube which houses, in order from top to bottom, the internal electrode, an inorganic cation exchanger for trapping silver ions and/or chloro complex ions from leaching from the internal electrode, and a ceramic member for preventing the diffusion of the silver ions and/or the chloro complex ions to the internal filling solution.

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: For simplified supply of potentiometric sensors with a reference electrolyte, a sensor plug head for connecting to a cable connection piece of a potentiometric sensor is provided. The sensor plug head including, besides the usual electric connections, a supply connection for connecting to a reference container of the potentiometric sensor. The supply connection includes, preferably, an electrolyte line and the reference container an opening, with the electrolyte line being connectable to the opening, in order to supply the reference container with electrolyte.

Abstract: A pressure-resistant reference electrode for electrochemical measurements includes both a half cell and a primary current bridge, provided for closing an electrochemical contact between the half cell and a measurement medium, which current bridge contains a primary electrolyte. The half cell has a reference electrolyte and a lead-off element, dipped into the reference electrolyte, which are disposed in a half-cell chamber that is provided with a primary junction leading to the primary current bridge and is otherwise embodied as medium-proof. The half-cell chamber furthermore has a flexible wall region, which is embodied such that a pressure difference between the primary current bridge and the half cell can be compensated for essentially without convection by the primary junction.

Abstract: A system for monitoring a pH level of a sample medium is disclosed herein as including a pH probe having a pH-sensitive electrode, a reference electrode and a temperature electrode arranged within a housing of the pH probe. The probe housing generally includes a flexible inner tube and a flexible outer tube, the inner tube being concentrically arranged within the outer tube. Preferably, a size of the probe housing minimizes the amount of trauma introduced by insertion of the pH probe into physiological tissues, muscles or fluids. The system also includes a processing means, which is coupled to the pH probe for determining the pH of the sample medium. A method of forming a pH-sensitive electrode, a method of manufacturing a pH probe, and a method for using a pH probe are also disclosed herein.

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 relates to planar electrochemical sensors with membrane coatings used to perform chemical analyses. The object of this invention is to provide unit-use disposable sensors of very simple and economical construction, preferably with only a single membrane coating on an electrode. The invented devices are potentiometric salt-bridge reference electrodes constructed with a heterogeneous membrane coating of a conductor. The heterogeneous membrane is a formulation that concurrently supports non-volatile species transport through an electrolyte compartment and gas transport through a hydrophobic compartment.

Abstract: An electrochemical cell assembly including a plurality of testing cells, a reference cell, and fluid connections between the testing cells and the reference cell. Each of the testing cells includes a working electrode, which is a rotating disk or ring-disk electrode, and a counter electrode. A chemical composition, whose intrinsic kinetic properties under defined mass-transfer are to be investigated, is deposited on the working electrode. The reference cell holds a reference electrode that serves as a common reference electrode for each of the testing cells. The assembly permits simultaneous testing of many chemical compositions under identical environment.

Abstract: A flowing junction reference electrode comprises a microfluidic liquid junction member situated between a pressurized reference electrolyte solution and a sample solution. This liquid junction member has an array of nanochannels spanning the member and physically connecting the electrolyte and the sample. While the electrolyte flows through the nanochannels and into the sample, the sample does not substantially enter the nanochannels via diffusion, migration, convection or other mechanisms. The number of nanochannels in the array can be between 10 and 108. Preferably, the nanochannels are substantially straight and parallel to one another. The nanochannels can have widths of between 1 and 500 nanometers, and the width of any one nanochannel is substantially equal to the width of any other nanochannel. The member can be manufactured out a polymer such as polycarbonate and polyimide, and may also be made of silicon, glass, or ceramic.

Abstract: The present invention disclose a method for fabricating planar reference electrodes. Particularly, the present invention relates to the planar reference electrode comprising plate (4); electrode connection (1); electrode (3); insulating membrane (2); inner reference solution (5); junction (7 or 9); and protecting membrane (6, 8 or 9), and processes for fabrication thereof, in which the junction is composed of porous material such as cotton thread, glass fiber, cellulose nitrate, cellulose acetate, filter paper and any material that can produce capillary action; porous polymer membrane; or a capillary either directly printed on the substrate or inserted with a thin film. The planar reference electrode of the present invention exhibit stable electric potential and short activation period, and may be used in both potentiometry and voltammetry. The planar reference electrodes of the present invention can be easily miniaturized and mass produced.

Abstract: Disclosed are systems and methods that include a flow-cell that includes porous conductive material(s) that provides a working electrode(s), an inlet connected to the flow-cell to deliver a solution continuing an analyte(s), an outlet connected to the flow-cell to allow the solution to exit the flow-cell, a counter electrode positioned proximate to the outlet, and a voltage source(s) coupled to the working electrode(s) and the counter electrode. The methods can include delivering a solution containing an analyte(s) through an inlet to a flow-cell that includes porous conductive material(s) that provides a working electrode(s), connecting the flow-cell to an outlet for allowing the solution to exit the flow-cell, placing a counter-electrode proximate the outlet, and supplying a voltage from a voltage source(s) to the working electrode(s) and/or the counter-electrode.

Abstract: A method and apparatus for automatically refilling reference electrodes used in chemical analysis. The apparatus generally includes a reference electrode including an outer chamber with an electrolyte contained therein, an adapter to secure the plumbing to the reference electrode, and a computer to control the refill unit. The refill unit further includes a pump, a refill bottle, and plumbing to connect the refill bottle to the pump and the pump to the reference electrode. The method generally includes drawing refill electrolyte from a refill bottle and pumping the refill electrolyte to the reference electrode. Embodiments of the invention further include an automatically refillable reference electrode.

Abstract: The invention relates to a durable and reliable miniature liquid junction reference electrode for use with at least one electrode (e.g., an electrochemical sensor cartridge) for measuring certain characteristics of a fluid sample such as blood or other body fluid.

Abstract: The invention concerns an electrode device comprising an ion selective material, a solid state, inner reference system of sodium vanadium bronze and a contact material, where sodium may be reversibly intercalated, in the bronze. Such an electrode device may for instance be sensitive to ions, such as H+, Na+, K+and Ca2+. It may also include a reactive material in which a particular analyte is reacted to form an ion product, to which the ion selective material is sensitive, such as in electrode devices of the Severinghaus-type or in biosensors. The electrode device according to the invention can be prepared by thick film printing.

Abstract: A flowing junction reference electrode comprising a liquid junction member matched with a filter. The junction member and the filter are situated between a reference electrolyte solution and a sample solution. An array of nanochannels spans the junction member and provides fluid communication between the electrolyte solution and the sample solution. The filter is configured to allow a greater flux of electrolyte than that associated with the junction member. Preferably, the number of pores is greater than the number of nanochannels. The filter is preferably configured to have pores with an inner diameter that is the same or less than the inner diameter of the nanochannels. In some embodiment, the resistance of the filter is made lower relative to the resistance of the junction member by selecting suitable length, number, and inner diameter size for the pores of the filter relative to the nanochannels of the junction member.

Abstract: A modular reference electrode assembly having a constrained-diffusion liquid junction between a liquid junction solution and a sample solution having separate flow paths, said assembly comprising a flow cell having attached thereto a constraint comprising a region of porous material permeable to water and salts; a remote reservoir for holding said liquid junction solution; a means for moving said liquid junction solution from said reservoir to said constraint; and a reference contact region is provided. This unique configuration provides a reference electrode device of the constrained-diffusion liquid junction type useful in pH and/or ion-selective electrode (ISE) potentiometric sensors and is particularly suitable for use in a mini-integrated electrochemical analyzer.

Abstract: Disclosed is a polymeric reference electrode membrane comprising (a) one selected from a porous polymer or a hydrophilic plasticizer; (b) a lipophilic polymer; and optionally an adhesion-enhancing material. A reference electrode equipped with the polymeric reference electrode membrane can be shortened the preconditioning time, and extended lifetime for storage and use owing to excellent adhesion, and showed reproducibility and good yield. So, a miniaturized multi-potentiometric sensor can be fabricated comprising a solid-state reference electrode of the present invention and a set of ion-selective electrodes, thus being useful in the potentiometric fields, including clinical, environmental, food and industrial analysis.

Abstract: A hand-held portable drug monitoring system to detect and quantitate cocaine and other organic drugs in saliva, sweat, and surface wipes by using an ion selective electrode or an array of ion selective electrodes. The ion selective electrode has a cast membrane reference electrode and a sensing electrode with a hydrophobic polymer, a plasticizer, and an ionophore selective for the organic drug to be tested. The ion selective electrode can be connected to a converter that coverts a voltage reading from the ion selective electrode to a quantitative drug concentration level. Also disclosed is the related method of using an ion selective electrode to detect an organic drug in saliva, sweat, and surface wipes, the method of testing electrical contact in an ion selective electrode, and the method of making a cast membrane reference electrode.

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: A potentiometric sensor for wellbore applications having a permanent aqueous contact between measuring and reference electrode, whereby contact is ensured by discharging the internal solution from the reference electrode directly onto a measuring (ion-sensitive) membrane and protecting the reference junction of the reference electrode with water wet porous material, such as sintered glass. It is advantageously applied to oil-water mixtures under high pressure and/or temperature.

Abstract: A reference electrode assembly having a constrained-diffusion liquid junction between a liquid junction solution and a sample solution having separate flow paths, said assembly comprising a flow cell having attached thereto a constraint comprising a region of porous material permeable to water and salts; a remote reservoir for holding said liquid junction solution; a means for moving said liquid junction solution from said reservoir to said constraint; and a reference contact region is provided. This unique configuration provides a reference electrode device of the constrained-diffusion liquid junction type useful in pH and/or ion-selective electrode (ISE) potentiometric sensors and is particularly suitable for use in a mini-integrated electrochemical analyzer.

Abstract: Sensors and methods of making the same are disclosed. Sensors are microfabricated with multiple working electrodes and a single, common counter electrode. The multiple working electrodes can be fabricated in different geometrical configurations for advantageously analyzing multiple components simultaneously in the same microcell sensor. Furthermore, sensors according to certain embodiments of the invention include openings to allow photometric analysis along with electroanalytical methods.

Abstract: The present invention relates to a device and method for measuring the level of an oxidant or antioxidant analyte in a fluid sample. The device comprises a disposable electrochemical cell, such as a thin layer electrochemical cell, containing a reagent capable of undergoing a redox reaction with the analyte. When the device or method is to be used with slow-reacting analytes, heat may be applied to the sample by a resistive heating element in the device or by an exothermic material contained within the electrochemical cell. Application of heat will accelerate the rate of the redox reaction between the reagent and the analyte and thus facilitate the electrochemical measurement of slow-reacting analytes.

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

Abstract: A flowing junction reference electrode comprises a microfluidic liquid junction member situated between a pressurized reference electrolyte solution and a sample solution. The liquid junction member has an array of nanochannels spanning the member and physically connecting the electrolyte and the sample. The number of nanochannels in the array can be between 10 and 108. Preferably, the nanochannels are substantially straight and parallel to one another. The nanochannels can be coated to facilitate the flow of the electrolyte solution through the junction member. The nanochannels can have widths of between 1 and 500 nanometers, and the width of any one nanochannel is substantially equal to the width of any other nanochannel. The member can be manufactured out a polymer such as polycarbonate and polyimide, and may also be made of silicon, glass, or ceramic. In one embodiment, the reference electrode includes means for pressurizing the electrolyte solution.

Abstract: A flowing junction reference electrode comprises a microfluidic liquid junction member situated between a pressurized reference electrolyte solution and a sample solution. This liquid junction member has an array of nanochannels spanning the member and physically connecting the electrolyte and the sample. While the electrolyte flows through the nanochannels and into the sample, the sample does not substantially enter the nanochannels via diffusion, migration, convection or other mechanisms. The number of nanochannels in the array can be between 10 and 108. Preferably, the nanochannels are substantially straight and parallel to one another. The nanochannels can have widths of between 1 and 500 nanometers, and the width of any one nanochannel is substantially equal to the width of any other nanochannel. The member can be manufactured out a polymer such as polycarbonate and polyimide, and may also be made of silicon, glass, or ceramic.

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: Disclosed is an electrochemical sensor comprising a work electrode and a reference electrode, said sensor adapted to measure the characteristics of a liquid under test, based on the relative electric potential difference and electric current between the work electrode and the reference electrode both immersed in the liquid under test, said work electrode comprising a substrate that reacts to the liquid under test for generating an electric potential according to the concentration of the liquid under test, and said reference electrode comprising a substrate that reacts to the liquid under test for generating a fixed electric potential. According to the present invention, at least one of the work electrode and the reference electrode comprises said substrate coated with a function film for serving to generate the electric potential through the intervention of the film between said substrate and the liquid under test.

Abstract: A reference electrode traps silver ions and chloro complex ions leaching to an internal filling solution so that the blocking of the liquid junction can be prevented. A silver/silver chloride electrode can be provided as an internal electrode in an internal filling solution; and a tube which houses, in order from top to bottom, the internal electrode, an inorganic cation exchanger for trapping silver ions and/or chloro complex ions from leaching from the internal electrode, and a ceramic member for preventing the diffusion of the silver ions and/or the chloro complex ions to the internal filling solution.

Abstract: A polymer electrolyte for an electrochemical half cell, in particular for a reference half cell, contains a polymer which as a first monomer component contains at least one alkyl methacrylate. The alkyl methacrylate has a substituted alkyl group with from three to seven carbon atoms and at least two substituents. The aforementioned substituents are selected from the group comprising OR1 and NR2R3, in which R1, R2 and R3 are selected from the group comprising hydrogen, methyl, and ethyl, on the condition that the substituted alkyl group contains the substituent OH at most once.

Abstract: A pressure-resistant reference electrode for electrochemical measurements includes both a half cell and a primary current bridge, provided for closing an electrochemical contact between the half cell and a measurement medium, which current bridge contains a primary electrolyte. The half cell has a reference electrolyte and a lead-off element, dipped into the reference electrolyte, which are disposed in a half-cell chamber that is provided with a primary junction leading to the primary current bridge and is otherwise embodied as medium-proof. The half-cell chamber furthermore has a flexible wall region, which is embodied such that a pressure difference between the primary current bridge and the half cell can be compensated for essentially without convection by the primary junction.

Abstract: A method and apparatus for automatically refilling reference electrodes used in chemical analysis. The apparatus generally includes a reference electrode including an outer chamber with an electrolyte contained therein, an adapter to secure the plumbing to the reference electrode, and a computer to control the refill unit. The refill unit further includes a pump, a refill bottle, and plumbing to connect the refill bottle to the pump and the pump to the reference electrode. The method generally includes drawing refill electrolyte from a refill bottle and pumping the refill electrolyte to the reference electrode. Embodiments of the invention further include an automatically refillable reference electrode.

Abstract: A flowing junction reference electrode exhibiting heretofore unattainable potentiometric characteristics is described, comprising a microfluidic liquid junction member that is situated between a reference electrolyte solution and a sample solution. This microfluidic liquid junction member has an array of nanochannels spanning the member and physically connecting the reference electrolyte solution and a sample solution, but while the electrolyte solution flows through the array of nanochannels and into the sample solution at a linear velocity, the sample solution does not substantially enter the array of nanochannels via the mechanisms of diffusion, migration, convection or other known mechanisms. The number of nanochannels in the array is preferably between approximately 108 and approximately 100. Also preferably, the nanochannels are substantially straight and are substantially parallel to one another; such an array of nanochannels is herein described as anisotropic.

Abstract: A silver/silver halide electrode composed of a non-electroconductive support sheet, a silver metal layer and a silver halide layer in order, is improved in its sensitivity by making the silver halide layer almost free from heavy metal element, for instance, by oxidizing the silver metal layer on its surface side with an oxidizing compound containing no heavy metal element or a chelated ferric oxidizing compound in the presence of a halide containing no heavy metal element.

Abstract: A flowing junction reference electrode exhibiting heretofore unattainable potentiometric characteristics is described, comprising a microfluidic liquid junction member that is situated between a reference electrolyte solution and a sample solution. This microfluidic liquid junction member has an array of nanochannels spanning the member and physically connecting the reference electrolyte solution and a sample solution, but while the electrolyte solution flows through the array of nanochannels and into the sample solution at a linear velocity, the sample solution does not substantially enter the array of nanochannels via the mechanisms of diffusion, migration, convection or other known mechanisms. The number of nanochannels in the array is preferably between approximately 108 and approximately 10. Also preferably, the nanochannels are substantially straight and are substantially parallel to one another; such an array of nanochannels is herein described as anisotropic.

Abstract: A neural control logic scheme based on prediction and pattern recognition techniques is used to control electrochemical processes such as aluminum electrolytic cells. The predictive capacity of feedforward neural networks is used to predict the future values of decision variables to be used by the cell's control logic, enabling the control logic to apply anticipated actions to cells in different conditions, thus avoiding anode effects and improving cell stability. The pattern-recognition capacity of LVQ-type neural networks is used to provide a closed-loop control structure to the feeding of the cell as a function of cell resistance, alumina concentration and cell condition. The closed-loop control structure enables the cell to operate at a near-optimal regime regardless of the condition of the cell.

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 flowing junction reference electrode exhibiting heretofore unattainable potentiometric characteristics is described, comprising a microfluidic liquid junction member that is situated between a reference electrolyte solution and a sample solution. This microfluidic liquid junction member has an array of nanochannels spanning the member and physically connecting the reference electrolyte solution and a sample solution, but while the electrolyte solution flows through the array of nanochannels and into the sample solution at a linear velocity, the sample solution does not substantially enter the array of nanochannels via the mechanisms of diffusion, migration, convection or other known mechanisms. The number of nanochannels in the array is preferably between approximately 108 and approximately 100. Also preferably, the nanochannels are substantially straight and are substantially parallel to one another; such an array of nanochannels is herein described as anisotropic.

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: The present invention relates to a filtration-detection device for detecting or quantifying an analyte in a test sample including a filtration device having a first binding material immobilized thereto, wherein the first binding material is capable of binding to a portion of the analyte, and a detection assembly positioned relative to the filtration device to detect or quantify analyte bound to the first binding material. The present invention also relates to methods of using the filtration-detection device.

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: The invention relates to reference electrodes for use in voltammetric measuring chains for oxidative as well as reductive detection of analytes, which are open with respect to the measuring medium. A metal-containing phthalocyanine or a metalloporphyrin is employed as potential-determining electrode material for reference electrodes of the invention used in oxidative detection. A fourth period metal, preferably copper, and a salt of said metal is employed as potential-determining electrode material for reference electrodes of the invention used in reductive detection. The potential-determining electrode material is coated as a layer or component of a layer on a planar support. The open reference electrodes according to the invention are particularly suited for voltammetric chemo- or biosensors having a planar structure.

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

Abstract: 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: The reference electrode comprises an electrode plug and a chamber (16) closed at the rear containing an electrolyte. The chamber (16) has an aperture (23) covered by a membrane (26) of a material permitting diffusion of ions therethrough, but whose surface is closed for proteins and similar macromolecular substances. A diffusion tight diaphragm element (27) having a through-going orifice (30) located radially within the aperture is situated on the outer side of the ion diffusion membrane (26) relative to the chamber, and the orifice (30) is smaller than the aperture (23).

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.