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

Abstract: An ion sensitive electrode device and method of its use in analytical and clinical chemistry are provided for measuring the concentration of an ionizable analyte contained in an aqueous medium. The device with external circuit means includes an electrode pair adapted to be placed in electrochemical contact with the medium. The electrode pair includes a polarographically active base metal/metal oxide working electrode and a reference electrode. The external circuit means is adapted to measure the voltage generated by the electrode pair in open circuit and to measure the closed circuit current flow at a preselected impedance and including means for comparing said voltage and current flow values with predetermined reference standards to provide a third value representative of said analyte concentration.

Abstract: The present invention describes devices capable of sensing changes of acidity in a non-aqueous medium. The devices are particularly useful for determining the alkaline reserve in a motor vehicle lubricating oil.

Abstract: Disclosed is a method of determining the state of charge and discharge of a host material, e.g., a hydride forming hydrogen storage material, or the interstitial content of an alloy material by the high frequency measurement of the time varying transfer function thereof.

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

Abstract: An electrochemical sensor capable of determining the partial pressure of various gases (e.g., CO, CO.sub.2, H.sub.2 S, alcohol vapors, hydrocarbons, NO.sub.x, etc.) and, optionally, substantially concurrently, but independently, oxygen content in gases and liquids. The sensor measures the amount of chemisorbent species formed either electrochemically by partial reduction (such as "Reduced-CO.sub.2 " in the case of CO.sub.2) or partial oxidation (in the case of alcohol) or non-electrochemically via specific adsorption (in the case of CO and hydrocarbons) on platinum or other metals. The charge required to oxidize this chemisorbed species is proportional to the amount of adsorbate on the electrode surface which is made a reproducible and reliable function of the partial pressure of the gas to be measured. By the proper selection of the sensor construction and electrical parameters, high sensitivity, fast response time, and high selectivity can be obtained.

Abstract: Several types of new microelectronic devices including diodes, transistors, sensors, surface energy storage elements, and light-emitting devices are disclosed. The properties of these devices can be controlled by molecular-level changes in electroactive polymer components. These polymer components are formed from electrochemically polymerizable material whose physical properties change in response to chemical changes, and can be used to bring about an electrical connection between two or more closely spaced microelectrodes. Examples of such materials include polypyrrole, polyaniline, and polythiophene, which respond to changes in redox potential. Each electrode can be individually addressed and characterized electrochemically by controlling the amount and chemical composition of the functionalizing polymer. Sensitivity of the devices may be increased by decreasing separations between electrodes as well as altering the chemical environment of the electrode-confined polymer.

Abstract: The measuring device (10) comprises an ISFET (12) used as a chemically selective ion sensor, a reference electrode (20) positioned adjacent the ISFET (12), an amplifier (22) coupled to the ISFET and control/correction circuitry (30) coupled to the ISFET (12), to the reference electrode (20) and to the amplifier (22). The control/correction circuitry (30) is operable to maintain the drain-source current I.sub.DS of the ISFET (12) at a constant value and to correct drift effects of the ISFET (12) on the basis of the logarithmic equation:.DELTA.V.sub.p =A 1n(t/t.sub.o +1 )where:.DELTA.V.sub.p =potential driftA=scale factor for drift and amplitudet.sub.o =time constant defining the dependence on timet=time during which the sensor is operative in the event of continuous operation.

Abstract: The precipitation or deposition of particles from a solution in a cell (61) which an electric field is applied between an anode (65,67,68) and a cathode (66), typically an electrolysis cell for the co-precipitation of mixed oxides but also cells for electrodeposition or the electrophoretic deposition of colloidal particles, is controlled by measuring the pH of the solution in the cell using a probe (72) shielded in a tube (73) from the migrating electric current and from gas bubbles. The pH of the solution is then adjusted to a selected value as a function of the measured pH, e.g. by varying the electrolysis current or by bubbling in acid vapor, air or base vapor.

Abstract: A sensor system for measuring the pH level in a process flow pipe, such system utilizing a sensing electrode that fits within, and is protected by, a rugged cylindrical metallic sheath. The sensing electrode is slid by an insertion tube through a ball valve into the process flow pipe. Two spaced collars with two pairs of restraint cables cooperate to retain the sensor system in alignment during the insertion procedure. After insertion, the sensor system is held in position by the pair of shorter restraint cables extending between the collars, while a compression nut is advanced onto a tube fitting to mechanically join the insertion shaft to the sensor system.

Abstract: A multiple combination electrode with associated multi-point plug mount, wherein the three measuring systems provided are arranged in a single electrode shaft provided on its one end with the measuring plane and carrying on its other end a plug-mount part forming, together with an associated matching plug-mount part fixing the connection cable, a triple plug unit with concentrically arranged plug contacts.

Abstract: A normal pH sensitive glass electrode is deactivated by exposure to thermal treatments at relatively high temperatures of approximately 190.degree. C. for predetermined periods of time until the nominal electrode sensitivity is reduced to very low levels such that the output potentials of such deactivated glass electrode approach the characteristics desired for a theoretically perfect reference electrode.Additionally, a method of forming a deactivated pH glass electrode including the steps of exposing a normal pH or other ion sensitive glass electrode to high temperatures in the order of 190.degree. C. or higher for predetermined periods of time is disclosed.

Abstract: The continuous monitoring of an element in a molten substance containing same is effected by monitoring the electromotive force generated between a first electrode in contact with the substance and a second electrode in contact with a reference material which is separated from the substance by a solid electrolyte. The reference material comprises a metal and at least one salt selected from the group consisting of (a) a combined salt of the metal and a monovalent metal, (b) a mixture of a first salt of the metal and a second salt of the monovalent metal, the first and second salts having a common anion, (c) a mixture of the first salt and the combined salt, and (d) a mixture of the second salt and the combined salt, the at least one salt being present in the form of a slurry containing a liquid phase in equilibrium with a solid phase, the liquid phase containing the metal and monovalent metal in ionic form and the solid phase containing the first salt, second salt or combined salt.

Abstract: A combination pH/reference electrode is provided with the two electrochemical references being symetrically thermally insulated from the sensing membrane and being thermally adjacent each other. The portion of the pH fill buffer in contact with the inner surface of the sensing membrane is thermally insulated, as by KCl crystals, to rapidly equilibrate in temperatures with the sample solution.

Abstract: An oxygen probe for measuring the carbon potential of endothermic gas in a heat treating furnace. The probe uses a readily available, automative-type oxygen sensor having a solid electrolyte element. The sensor is mounted on a heat conducting base plate. The sensor element is surrounded by a gas flow tube extending from the base plate. Exit ports around the base of the sensor element extend through the base plate and into the area defined by the gas flow tube causing an axial, radially symmetric flow of gas around the sensor element. The tip of the element is heated above the temperature of the gas while the base of the element is conductively cooled by the base plate. A temperature gradient is thus caused along the length of the sensor element, increasing its sensitivity.

Abstract: The present invention includes a system for mounting a sensor probe through the wall of a chemical vessel or other fluid container such that a sensing element can be located within. The system includes means for maintaining the sensing probe within the vessel in a fluid-tight, elevated temperature-resistant and corrosion-resistant seal. The system further includes provisions for removing, from the exterior of the reactor vessel, the sensing probe from the fixed sensing probe holder assembly which is within the interior of the reactor vessel. Further, means are included by which a sensing probe of an extended length which is mounted through the top of a chemical reactor vessel, can be inserted into and removed from the reaction vessel even with a low overhead situation above the uppermost portion of that reactor vessel.

Abstract: A pH sensor includes a substrate formed of an electrically conductive carbon material. A hydrogen ion-sensitive layer is formed on the substrate surface. The layer is formed of an electrooxidation polymer of a nitrogen-containing aromatic compound selected from the group consisting of 1-aminopyrene and a mixture of 1-aminopyrene and pyridine.

Abstract: A pH measurement device includes working and reference electrodes. The working electrode has a linear electrically conductive substrate, at least a distal end surface of which consists of platinum, and a selective hydrogen ion permeable layer formed on the distal end face of the substrate. The reference electrode includes an electric conductor formed to be insulated from the working electrode and surrounding the working electrode, a polymer-silver (I) complex layer formed on the outer circumferential surface of the conductor, and an ion-conductive layer containing an anionic compound and formed on the complex layer. The pH of a solution is measured in accordance with a difference between a potential of the working electrode and that of the reference electrode.

Abstract: An improved solid state electrode system for measuring the pH of fluids at temperatures as high or even higher than that corresponding to the critical point of water (374.2.degree. C.). A stabilized metal oxide based ceramic member having a predetermined thickness is coupled to a first metallic conductor by a uniform, solid oxygen-free electrolyte to serve as a pH sensing electrode. A body of an electrochemically inert material, which preferably comprises a stabilized metal oxide based ceramic member having a lesser thickness or a greater porosity, is coupled to a second metallic conductor by a similar uniform solid electrolyte to serve as a reference electrode. Together the pH and reference electrodes form an electrode system that is suitable for use in applications in which the temperatures and/or pressures of the test solution preclude the use of conventional electrodes. A variety of configurations and compositions are disclosed which allow the electrode system to be fabricated in an improved manner.

Abstract: A selectively permeable film directly applied to coat the surface of an electroconductive element, said electively permeable film comprising a polymer which is derived from at least one aromatic compound selected from the group of nitrogen-containing aromatic compounds or from the group of hydroxy aromatic compounds. The nitrogen-containing aromatic compounds are aniline, 2-aminobenzotrifluoride, 2-aminopyridine, 2,3-diaminopyridine, 4,4'-diaminodiphenyl ether, 4,4'-methylenedianiline, tyramine, N-(o-hydroxybenzyl)-aniline and pyrrole. The film coated on the electrode surfaces permits selective passage of ions and the electrode can be used as an ions sensor for measuring the concentration of ions in solutions.

Abstract: A solid state electrode that includes a graphite core as both the internal reference and the electrical conductor that is preferably formed of graphite threads maintained as a bundle that in one embodiment, has an end thereof coated with a mixture of antimony and antimony oxide as a sensor element, the graphite junction forming the internal reference to that sensor element, and in another embodiment, the graphite core is wrapped tightly around a sensor formed from section or "shot" of a mixture antimony and antimony oxide, the graphite junction forming the internal reference thereto. The connected graphite core and antimony/antimony oxide sensor are then covered with an impermeable non-conductive plastic sheath, leaving a section of the antimony/antimony oxide sensor surface exposed, and the junction of that sheath to the antimony/antimony oxide sensor is preferably sealed as with an epoxy.

Abstract: A new reference electrode assembly is provided that includes a hydrogen ion specific electrode which is encapsulated in a polymer matrix. The bulk of the polymer matrix has an open cell structure within which a liquid is contained as the electrode potential producing agent, while its surface is such that it forms a barrier preventing a free and open connection to the environment of the reference electrode. The reference electrode assembly is especially suitable for in vivo measurements, and it may be designed so that it is substantially insensitive to pH variations of the solution being measured by the instrument of which the reference electrode assembly is a part.

Abstract: A cylindrical closed housing formed of clear material provides a test flow cell for monitoring the halogen and pH level in a flowing liquid stream. The cylindrical housing includes a circumferential, longitudinally extending side surface with front and back end surfaces secured to the circumferential cylindrical surface to form the closed, hollow housing test cell. The housing has a first inlet opening at one side for the liquid stream; an outlet opening for the liquid stream at the top of the housing and a second inlet opening for acid at the bottom of the housing. A pair of additional openings, one on each side of the outlet opening receives and positions electronic sensing probes diagonally within the test flow cell; the probes terminate between the top outlet and bottom second inlet openings and opposite the first inlet side opening.A controller includes circuitry which enables the halogen and pH levels desired in a reservoir of water to be preset.

Abstract: A transcutaneous blood carbon dioxide sensor together with a method for making such a sensor and for making electrodes used in the sensor. The sensor comprises a palladium/palladium oxide junction type electrode and a silver/silver halide junction type electrode applied to an electrically nonconductive substrate, partially coated with an insulative dielectric and partially coated with a polymeric membrane material including a bound electrolyte, the polymeric membrane material being permeable to carbon dioxide. The Pd/PD0 electrode was made cathodic prior to terminating the electro-oxidizing conditions.

Abstract: A method and apparatus for rapidly detecting toxicants via the use of a ft CO.sub.2 sensing cell and a second reference CO.sub.2 sensing cell, with each sensing cell including a first chamber and a second chamber, separated by a CO.sub.2 permeable membrane, and a pH sensor disposed in each of the second chambers. The method includes the step of placing distilled water in the first chamber of each cell, and allowing its dissolved CO.sub.2 to become equilibrated with the water in the second chamber, from which it is separated by the CO.sub.2 permeable membrane. Next, exact amounts of a microorganism and sugar are added to small dishes in the first chambers along with control vegetation for one dish and vegetation to be tested to the other dish. Then the first chambers are completely filled with distilled water and the dishes are agitated to facilitate a solution of microorganisms and sugar.

Abstract: A method of electrometrically monitoring the pH of an electrolyte in an electrolytic cell with a pH sensor having a reference electrode with a porous membrane is provided by placing the pH sensor in the electrolyte flow stream, floating the reference electrode at the cell potential, and monitoring the pH sensor readings via potential measuring apparatus.

Abstract: Process and apparatus for directly measuring the ion strength of an electrolyte solution is disclosed. The pH value of the electrolyte is measured by means of a first measurement with a first indicator dependent on the ion strength and by means of a second measurement with a second indicator dependent on ion strength in a manner different from the first indicator whereby the ion strength is computed by means of the approximation ##EQU1## J=ion strength Jo=ion strength upon calibrationpH'(N)=pH value, measured with a first indicator N dependent on the ion strength (HPTS)pH'(X)=pH value, measured with a second indicator X dependent on the ion strength, the ion strength dependence of which is different from that of the first indicatorW(N)=valency of the first indicatorW(X)=valency of the second indicatorwith ##EQU2## The ion strengths of other ions and of unknown electrolyte may also be computed.

Abstract: There is provided an ISFET structure and a method for manufacturing that structure such that external electrical contact to the P+ source and drain regions is made through individual holes etched from the back to the source and drain regions with sidewall isolation being provided in the holes and metallization covering the surface of said sidewalls and extending to contact pads on the back of the ISFET.

Abstract: An electrochemical cell is provided with plural identical selective electrodes and at least one chemical reactor for the indirect measurement of clinical-chemical parameters. The electrodes are ion-selective for the same ionic species or gas-selective for the same gaseous species. One of the two electrodes can be used as a measuring electrode and the other as a reference electrode. In the case of gas-selective electrodes, the reference electrode can be selective for a different ionic species. A third electrode with just electrical conducting properties can be provided. The chemical reactor can utilize immobilized enzymes, or immobilized substrates, or ion exchange resins, and is preferably connected to the measuring electrode only. Two fluidic paths may be provided in the electrochemical cell, as well as one input and two outputs, or two inputs and just one output in sequence.

Abstract: A process and apparatus for the determination of the activity of carbon in furnace atmospheres involves the measuring of the ratio of the partial pressure of oxygen in the furnace gas with respect to a reference gas with the aid of an electric potential furnished by oxygen ion conducting solid state cells. The reference gas comprises the furnace gas brought into a Boudouard equilibrium at the furnace temperature. The exchange takes place in a comparison chamber with a time constant 1/10 of that of the furnace. Thus, the activity of carbon may be calculated or calibrated by a formula which includes the electric potential furnished by the solid cells and the absolute temperature, but which does not include the CO content or the pressure. The process may thus be operated without regard for the CO content in the furnace atmosphere.

Abstract: A pH electrode which is capable of withstanding repeated exposures to sterilizing temperatures. An electrode body having a pH sensing member is at least partially filled with a bed of electrochemically inert particles. After an internal reference is inserted into the particle bed, the bed is injected with a quantity of electrolyte which is sufficient to establish continuity between the sensing member and the internal reference, but which is not sufficient to produce destructive internal pressures when the electrode is subjected to sterilizing temperatures. The electrode is completed by forming a seal between the electrode body and the internal reference.

Abstract: The invention relates to methods of controlling the precipitation or depositing of particles from a solution in a cell in which an electric field is applied between an anode and a cathode, in particular the precipitation of metal compounds such as oxides and hydroxides and the coprecipitation of mixed metal oxides from a solution of the metal salt(s) in an electrolysis cell, but also the electrolytic deposition of cathodic metal deposits as well as the electrophoretic deposition of colloidal particles.

Abstract: An ion measuring device (pH meter) is adapted to store and discharge standardizing solution, as well as to provide measurements of the hydrogen or other ion concentrations of unknown samples; the device including a working electrode of known construction and a reference electrode adjacent to the working electrode; and further including at least one storage reservoir for containing a standardizing solution, and a measuring or standardizing chamber located at the lower end of the reservoir with means, preferably in the form of a valve, for permitting communication between the reservoir and standardizing chamber such that standardization and calibration can be carried out.

Abstract: A reference electrode (102), standard calibration solutions (72 and 76) and a sample solution (80) are all placed in liquid contact with one another and a reference solution (70). Contact between the reference solution (70), the sample (80) and the calibration solutions (72 and 76) is made through salt bridges (82, 74 and 78). A special conical shaped solution container (FIG. 5) having a porous plug or other salt bridge extending through the container wall at the apex provides special advantage.

Abstract: A transcutaneous gas measuring assembly is described in which a glass electrode is formed by a body of highly insulating material and a bottom by a glass membrane. The membrane is provided with a conductive layer on the inner surface thereof and a preamplifier is disposed within the glass electrode and electrically connected to the conductive layer. A reference electrode is disposed around the glass electrode. All of the above form a measuring portion of the gas measuring assembly.

Abstract: A pH sensor comprising a sleeve assembly having at least first and second spaces, a partition separating the two spaces from each other with a water tight seal, and a barrel including a flange, a reference electrode accommodated in the first space and including a liquid junction, a glass electrode having a sensor unit disposed adjacent to the liquid junction, liquid grounding means mounted adjacent to the liquid junction, and a cable disposed in the second space with a watertight seal, the cable being electrically connected to the reference electrode, glass electrode and liquid grounding means. The pH sensor can be used for continuous flow, immersion or submersion types of installations, and can be fabricated inexpensively and is easily maintained. The sensor unit of the pH sensor can be easily cleaned by a cleaning unit which includes a rotatable shaft to which is connected a vane and a brush at one end.

Abstract: A PH electrode is provided with an ISFET for generating a potential difference according to the PH value of an electrolyte to be measured, and includes a cell for driving the ISFET, so that the PH electrode can be used, as it is, with a conventional, potential difference type PH meter.

Abstract: Apparatus is disclosed for measuring the electrochemical activity of a liquid, for example, the hydrogen ion activity or pH value of blood. A disposable cartridge includes spaced indicating and reference electrodes which develop electrical properties as a function of the electrochemical activity. The cartridge carries a capsule containing an electrolyte solution. A machine for measuring the electrochemical activity includes a socket in a pivoting door for receiving the cartridge. When the door is pivoted into a closed position, the capsule is automatically crushed thereby covering the electrodes with the solution. The breaking of the capsule triggers an electronic measurement of the resultant electrical properties that develop between the two electrodes. This calibration factor is stored and used to compute the electrochemical characteristics of the sample when it is introduced into the cartridge to cover the indicating electrode.

Abstract: An electrode for measuring the pH of a liquid at high temperatures and pressures comprises a first hollow electrode formed of the ceramic which exhibits a pH-dependent potential thereacross and a second electrode provided with a porous ceramic junction. Two flexible-walled members are in fluid communication with the hollow interior of the two electrodes and are surrounded by a chamber whose pressure is kept substantially the same as that to which the electrodes are exposed. However, the chamber is thermally insulated from the hot solution whose pH is being measured. The interiors of the hollow electrodes and the flexible-walled members are filled with the same buffered solution and measuring electrodes are disposed within each of the flexible-walled members. The construction enables the measuring electrodes to be kept at substantially room temperature, thereby reducing chemical attack thereon and eliminates errors in potential measurement due to streaming and thermal diffusion potentials.

Abstract: A probe system is provided which may be removably installed in-line in a pressurized pipe line to determine the pH of the fluid flowing therethrough. The probe system comprises a mounting means exteriorly secured to the pipe line, a valve means in said mounting means and a cap means secured to the mounting means and having an opening therein. An elongated pH probe is inserted through said opening and is secured by said mounting means while the probe tip is disposed within the pipe line. The probe includes a transducer for converting the acidity of the fluid flowing through the pipe line to an electrical signal representing the acidity, and a smooth, adherent plastic coating is provided on said probe to define an elongated sheath with a uniform, round circumference. A sealing means seals against the sheath to prevent fluid flow past the cap means, said sealing means permitting movement of the sheath relative to said cap means upon installation and removal of the probe within the pipe line.