Abstract: The concentration of an ionic species (e.g. K.sup.+) is determined using an ion sensitive electrode having an appropriate membrane (e.g. valinomycin in plasticised PVC). In place of a conventional reference electrode, the half cell is completed with an electrode having an identical membrane but lacking the constituent producing the ion-selective response (e.g. plasticised PVC). The working and reference electrodes can then be made in substantially the same manner to null of interferents. The difficulties associated with double junctions are avoided.

Abstract: A sensor for measuring the concentration of an analyte in a solution is disclosed. The sensor may be adapted for use as either an amperometric or a potentiometric sensor. It includes a membrane having a biologically active protein immobilized within. The membrane is attached and reliably sealed to a housing by means of ultrasonic welding, either directly or indirectly. Further, the membrane may be compressed to a fraction of its original dimensions. Metallic parts of the device may, optionally, be physically isolated from the sample solution to reduce corrosion. These features operate synergistically so that the claimed device exhibits relatively fast response and recovery times, is reliably leak-proof, and may be constructed in relatively small sizes.

Abstract: Ion sensor having an ion-selective electrode and a reference electrode, both being unified, without internal liquid solution. The ion-selective electrode part has a solid solution of halogenide of conducting ions of solid electrolyte and halogenide of metal for an internal electrode, e.g., NaCl-AgCl solid solution. The reference electrode part has a solid solution of halogenide of the group Ia or IIa, e.g., Na, K, and a halogenide of metal for an internal electrode, e.g., NaCl-AgCl solid solution. The electrode parts are supported by an insulating substrate. A solid electrolyte such as NASICON or ionophore such as valinomycin is used as an ion-sensitive membrane.

Abstract: A measuring circuit with a biosensor utilizing ion sensitive field effect transistors having a simplified structure and is advantageous to integration. The measuring circuit comprises two ion sensitive FET input devices composed of an enzyme FET having an enzyme sensitive membrane on the gate and a reference FET, and a differential amplifier for amplifying the outputs of the enzyme FET and the reference FET. The drift phenomena of the ISFETs due to the use of a non-stable quasi-reference electrode as well as the temperature dependence thereof can be eliminated by the differential amplifier consisting of MOSFETs having the same channel as the ISFETs. The ISFET biosensor and the measuring circuit can be integrated into one chip.

Abstract: In a miniaturizable, capacitively measuring chemical semiconductor-based sensor system consisting of a sensor and a reference element which are to be brought into contact with the electrolyte to be measured, the reference element being connected in series with the sensor, the reference element consists of a highly doped semiconductor substrate or metal/semiconductor substrate which is covered with a membrane, and the sensor consists of an insulator/semiconductor substrate which is coated with a sensitive membrane, and the sensitive membrane of the sensor is more sensitive than that of the reference element.The sensor and the reference element of this sensor system may either be applied to one and the same chip or consist of individual components which are readily interchangeable with one another.

Abstract: A method for separately detecting tastes of a plurality of similar samples by using a taste sensor employing a lipid membrane includes first, second, third, and fourth steps. In the first step, a reference solution having a taste identical or similar to one of the plurality of samples is prepared. In the second step, the reference solution is measured by using the taste sensor. In the third step, one of the plurality of samples is measured by using the taste sensor. In the fourth step, a relative value Vi-V0 of the sample is calculated from the measured value V0 of the reference solution and the measured value Vi of the sample. The second to fourth steps are repeatedly performed for each of the plurality of samples.

Abstract: The present invention relates to a combined semiconductor gas sensor, this sensor is constituted by combining two portions, each of the portions is made of a different gas sensitive material, their resistance exhibit different variation with the variation of the density of a specific gas, a detecting signal is led out from the junction of the two portion. Because of the mutual compensation and propagation effect of the two portions of the above mentioned gas sensor, the stability and/or sensitivity as well as the stability to temperature and humidity and the initial relaxation time can be improved. Gas sensors of different characteristics can be obtained by different combinations of two different gas sensitive materials selected according to need.

Abstract: Small quantities of liquid are conveyed, either for the purpose of filling micropipettes or to function as an electrolyte in an ion selective electrode, in a flexible non-metallic capillary tube which is mounted, at a first end, in an adapter fitting. The fitting defines a socket for coupling to a source of liquid, a hypodermic syringe for example, or for receiving an electrochemical half-cell which will contact an electrolyte in the tube. A filter may be interposed between the fitting and hypodermic syringe so as to frictionally engage both when the device is employed for filling micropipettes.

Abstract: A combination sampling/electrochemical analysis cell comprises an enclosure having a hollow therein, at least one inlet leading to the hollow, a vent leading from the hollow, at least one testing electrode, at least one counter electrode, and at least one reference electrode, all disposed at least in part in the hollow. A testing reagent is also contained in the hollow.

Abstract: The invention relates to measuring the concentration of ions in a medium. The potentiometric sensor of the invention comprises a body (7) in the form of a matrix body made of a single type of material which does not conduct electricity, which is chemically inert, and which is suitable for being filled with various materials in the dispersed, the dissolved, or the grafted state. A sensitive zone of the matrix body comprises a layer or thickness (9) of an ionically conductive material for being put into contact with the measurement solution, an underlayer or thickness (10) of an electronically conductive material, and an intermediate layer or thickness (11) providing intimate connection between said layer (9) and said underlayer (10). A conductor (12) passes through a portion of the matrix body (7) in sealed manner and is inserted into the underlayer (10). The sensor is particularly applicable to measuring biological fluids.

Abstract: An electrode for a biosensor (e.g., a glucose biosensor) has a layer of an electrically insulating polymer formed in situ on its operating surface by electropolymerization. For example, a diaminobenzene and a dihydroxybenzene (e.g., 1,3-diaminobenzene and resorcinol) are copolymerized on the electrode's surface by immersing the electrode in a circulating dilute solution of the monomers in deaerated phosphate buffer, and applying a small, continuously cycling voltage between that electrode and another electrode (e.g., from 0.00 V to 0.80 V) until current flow between the electrodes decreases to a minimum. Because the polymer is electrically insulating, polymerization ceases while the polymer layer is still very thin (e.g., 10 nm). An analyte sensing agent, e.g., an enzyme such as immobilized glucose oxidase, is imbedded in the polymer, but with a number of its analyte recognition sites unblocked.

Abstract: An improved solid-state ion-selective electrode has greater uniformity of asymmetric potential and high sensitivity and selectivity for the cation of interest. The electrode comprises: (1) a porous element comprising graphite; (2) an electrochemical reference in substantially dry form on at least a portion of the element, the reference comprising: (a) an oxidant and (b) a reductant that is the conjugate of the oxidant, the oxidant and reductant being present in about equimolar quantities; and (3) a polymeric membrane comprising an ion-selective ionophore in electrochemical contact with the electrochemical reference. The electrode can be prepared to be selective for one of a number of cations, including lithium and ammonium. Methods for preparing these electrodes are also disclosed.

Abstract: A combination sampling/electrochemical analysis cell comprises an enclosure having a hollow therein, at least one inlet leading to the hollow, a vent leading from the hollow, at least one testing electrode, at least one counter electrode, and at least one reference electrode, all disposed at least in part in the hollow. A testing reagent is also contained in the hollow.

Abstract: A solid state pH sensor having an indicator electrode of metal/metal oxide and a reference electrode of metal/metal salt applied to inert, electrical conductors imbedded in an electrically non-conductive substrate, such as a ceramic substrate. The sensing portion of the sensor preferably has a coating of an annealed perfluorocarbon copolymer. Alternatively, the indicator or reference electrodes may be formed on separate electrically non-conductive substrates with each having an inert electrical conductor imbedded therein. These indicator or reference electrodes may be utilized with each other or with prior art electrodes.

Abstract: A sensor 13 is inserted into a connector 14. A constant voltage required to obtain a response current is applied across the connector 14 by a voltage applying source 15 at timings required. A response current of the sensor 13 inserted into the connector 14 is converted into a voltage by a current-to-voltage converter 16, and the amount thereof is determined by a microcomputer, the analysis results being displayed onto a display unit.

Abstract: An improved enzyme electrode includes a three-dimensional redox polymer network having redox enzymes bound thereto, and also having a protein excluding polymeric coating.

Abstract: The present invention provides a biosensor comprising an electrical insulating substrate, a main electrode system formed on the substrate and having a working electrode and a counter electrode, a reaction layer provided in contact with or in the vicinity of the main electrode system and containing an oxidoreductase, and a sub electrode system as a reference provided with an interval from the main electrode system and having a working electrode and a counter electrode.

Abstract: An improved enzyme electrode includes a three-dimensional redox polymer network having redox enzymes bound thereto, and also having a protein excluding polymeric coating.

Abstract: An iodide-doped, polythienylene coated electrode suitable for a potentiometric iodide ion sensor and a method for its manufacture are disclosed. The electrode is prepared by polymerizing the polythienylene on a working surface thereof. To this end, the working surface is contacted with a monomer solution of thiophene monomer and an electrolyte dissolved in organic solvent. Thereafter the solution is subjected to either a substantially constant potential of about 1.6 volts to about 1.8 volts vs. Ag/AgCl or to a cycling potential between -0.1 volts and +1.8 volts vs. Ag/AgCl for a time period sufficient to polymerize a polythienylene film of the desired thickness onto the working surface of the electrode.The polythienylene film on the working surface is then doped with I.sub.2 by placing the coated electrode in an aqueous solution of iodide salt under applied potential conditions of about +0.6 volts to about +1 volt vs. Ag/AgCl for a period of time sufficient to dope the polymer.

Abstract: An electrolytic cell for the labeling of proteins, peptides and other organic molecules employs a cathodic half cell and an anodic half cell, where a porous working electrode is located in one half cell and a counter electrode is located in the other of the half cell, the two half cells being divided by a separator. A reference electrode located in the half cell containing the working electrode, and placed outside the current path between the working electrode and the counter electrode confers precise control of the working electrode potential, which allows the maximum rate of labeling to be achieved while minimizing oxidative damage to the protein, peptide or organic molecules. Saturation of the working electrode with non-radioactive label coupled with a ratio of working electrode surface area to volume of half cell containing the working electrode between 0.001 cm.sup.-1 to about 10 cm.sup.-1 minimizes the problem of loss of activity of radiolabel due to adsorption on the working electrode.

Abstract: Switching devices (10) comprise a micro-electrode (12 or 16a') coated with a templated polymer (14). For example, the template molecule is glucose and the bulk polymer is a thiophene/boronic acid-substituted thiophene copolymer. The switch is activated or inactivated by the concentration of glucose in a solution (38) contacting the coated micro-electrode. Advantageously, the dimensions of the switch may be very small, 10.sup.-6 or less.

Abstract: Phosphate ion-sensitive composition and ion-selective electrode are disclosed incorporating an ionophore having the formula:R.sub.1 -X (a)orX-Z-X (b)wherein R.sub.1 is H or a hydrophobic substituent, Z is a spacing unit and X is represented by the formula: ##STR1## wherein n=0 or 1 and R.sub.2 and R'.sub.2 are independently selected from the group consisting of CH.sub.2, C(O) or C(S).

Abstract: Radiation-sensitive compositions are disclosed of a type suitable for preparing ion sensitive membranes for electrochemical ion sensors. The compositions are comprised of a radiation-sensitive polymer containing radiation-sensitive recurring units having an ionophore group and recurring units having a crosslinking group. In preparing a membrane the radiation-sensitive composition is coated onto a sensor, exposed to activating radiation to produce crosslinking in areas where the membrane structure is desired, and removed in any remaining non-exposed areas.

Abstract: An ionophore according to the general formula I wherein the substituents are chosen such that the ionophore is either also polymerized in the matrix of a membrane selective for metal ions or interwoven therewith. Thus obtained is a membrane having a long useful life for use in diverse sensors such as ISFET, ion-selective electrode, and the like.

Abstract: An anion exchange membrane for ionic macromolecules, specifically heparin, which is formed of a polymeric matrix material, an anion exchange material suitable for heparin detection, and a plasticizer can be employed in an electrochemical sensor arrangement to directly measure the concentration of heparin ions in blood or blood fluid. Potentiometric response to heparin has been observed with membranes comprising 30-70 wt. % polymeric matrix material, such as polyvinyl chloride, 0.1-12 wt. % quaternary ammonium salt, such as tridodecyl methyl ammonium chloride, and 30-70 wt. % of a plasticizer, such as dioctyl sebacate.

Abstract: An enzyme sensor, which comprises an enzyme-modified electrode and a counter electrode, wherein the enzyme-modified electrode comprises, as electrode components, an enzyme and/or an enzyme-containing substance and mediator. The enzyme sensor is useful in analysis, such as the analysis of compounds in foods or components in the living body, the diagnosis of diseases and the control of reaction processes. The preparation of the enzyme-modified electrode is also described.

Abstract: An apparatus for the simultaneous measurement of a plurality of ionic concentrations can utilize a test station having a common support sheet for supporting a plurality of ion selective electrodes, reference electrode and pH responsive electrode. Simultaneous measurements can be taken at the same time from a single sample and the pH reference electrode can validate the operative range of an ion selective electrode.

Abstract: The present invention provides a biosensor comprising at least one lipid membrane, each membrane including at least one gated ion channel. The membranes comprise a closely packed array of self-assembly amphophilic molecules and the gated ion channel has a conductance which is dependent upon an electric field applied across the membrane. The biosensor of the present invention may comprise a plurality of discrete membranes each including at least one gated ion channel. The conductance of each of the membranes is measurable independently of the conductance of the other membranes.

Abstract: A polyviologen modified electrode which comprises an insoluble film of polyviologen polymerized on a base electrode by electrochemical reduction and electrodeposition of monomer represented by the formula (I) ##STR1## Wherein R.sup.1 is a divalent group selected from the groups consisting of alkylene, cycloalkylene, arylene and arylalkylene or a trivalent group selected from the groups consisting of alkanetriyl, cycloalkanetriyl, arylalkanetriyl and aryltriyl; X.sup.- is a counter anion; m is 2 or 3, which electrode has no performance problem in connection with the solubility to water and organic solvent and the annealing phenomenon.

Abstract: A body fluid sample is diluted with a diluent which comprises an aqueous solution containing bis(2-hydroxyethyl)-iminotris(hydroxymethyl)methane and boric acid to obtain a diluted body fluid sample, and the ion concentration in the diluted body fluid sample is determined with ion-selective electrodes, whereby the variation width of pH in the diluted body fluid sample can be held down to a narrow range. As a result the determination can be made without exerting adverse effects on the ion-selective electrodes, and errors in determination can be markedly reduced as compared with cases where the conventional diluents are used.

Abstract: An enzyme electrode is prepared with a composite coating on an electrical conductor. The composite coating is formed from a casting solution of a perfluorosulfonic acid polymer, an enzyme, and a carbon supported catalyst. The solution may be cast directly on the conductor surface or may be formed as a membrane and applied to the surface. The perfluorosulfonic acid ionomer formed from the casting solution provides an insoluble biocompatible protective matrix for the enzyme and acts to retain the enzyme for long term availability in the electrode structure. The carbon supported catalyst provides catalytic sites throughout the layer for the oxidation of hydrogen peroxide from the enzyme reactions. The carbon support then provides a conductive path for establishing an electrical signal to the electrical conductor.

Abstract: This invention relates to a semiconductor substrate having a porous surface nd to the amperometric receptor-based sensors formed with the substrate. More specifically, this invention pertains to the substrate in the form of a bipolar junction transistor having a porous hydrophilic surface directly on its base wherein the surface forms a support for an amperometric sensor. The invention also pertains to the methods of making and using the substrate and sensor.

Abstract: Self-assembly of a chemically insensitive redox material, such as ferrocenyl thiol, and a chemically sensitive redox material, such as a quinone thiol, onto microelectrodes forms the basis for a two-terminal, voltammetric microsensor having reference and sensor functions on the same electrode. Detection is based on measuring the potential difference of current peaks for oxidation and reduction of the reference (ferrocene) and indicator (quinone) in aqueous electrolyte in a two-terminal, linear sweep voltammogram using a counterelectrode of relatively large surface area. Use of microelectrodes modified with monolayer coverages of reference and indicator molecules minimizes the size of the counterelectrode and the perturbation of the solution interrogated. Key advantages are that the sensor requires no separate reference electrode and the sensor functions as long as current peaks can be located for reference and indicator molecules.

Abstract: The present invention relates generally to the immobilization or incorporation of polypeptides, especially enzymes or other bioactive polypeptides into polymeric matrixes, especially polyurethane, membranes produced by said polymers, and the utilization of such membranes in biosensors. A preferred type of biosensor is the needle sensor designed for in vivo monitoring of glucose which comprises a core platinum anode (2) coated with an insulating lacquer (3), the anode (2) is situated inside a stainless steel reference cathode (4) which is insulated from the anode (2) by a layer of epoxy resin (5) At one end, of the tip, the electrode (1) has a detection surface (6) which is in an acute angle to the general direction of the electrode (1). At the other end, the base, the electrode (2) is provided with terminals (7) and (8) for the anode (2) and cathode (4), respectively.

Abstract: A system for analyzing the ion level of a fluid sample including an analyzer instrument, containing electrical circuitry for analyzing the ion level of the fluid sample, in electrical communication with a sensor unit having an ion selective electrode in communication with the fluid sample and electrical contacts for communication with the analyzer instrument. A recharger unit for the analyzer instrument is also disclosed.

Abstract: A pH sensor has a core of an electrochemically inert insulating or semi-conductive material, and is coated with an electrically conductive, electrochemically sensitive coating. The preferred core is insulating and made of alumina, with a thin coating of iridium oxide deposited over at least a portion of the outer surface of the core. The coating is carried to a surface remote from the sensing surface and is used for making electrically conductive connections that lead to remote circuitry. The core is made in a form that can be supported and held in an insulating, electrochemically inert, deformable material that is sealed around the outer surface of the coating on the core to prevent leakage of chemicals being sensed. The body also permits sealing quite easily onto access ports on which the sensor housing is mounted. Various connections to the electrode coating can be made quite easily to provide for a unique sensor assembly.

Abstract: Disclosed is a method of measuring glucose concentration of a sample solution using a glucose sensor having an ion-sensitive field-effect transistor which can detect pH change in the sample solution provided with a glucose oxidase-immobilized film formed on the ion-sensing section thereof, which comprise a step of measuring the output of the glucose sensor under a low level of dissolved oxygen in the enzyme-immobilized film; a step of measuring the output of the glucose sensor under a high level of dissolved oxygen in the enzyme-immobilized film; and a step of determining the glucose concentration of the sample solution from the difference between said two output values. The measuring system can be simplified and working efficiency can be improved since the present measuring method requires neither a buffer nor correct measuring of the sample solution or buffer.

Abstract: A reference electrode for generating a reference potential on an ion sensor is disclosed. The reference electrode has a lamination film covering a surface of an electrically conductive substrate and formed by alternately laminating silver halide thin films and hydrophobic resin thin films.

Abstract: A lithium ion sensor includes a FET, a redox layer having a redox function covering a gate isolating membrance of the FET, and a lithium ion-sensitive layer selectively sensing lithium ion covering the redox layer.

Abstract: A film-coated sensor is formed by providing an electrically conductive substrate (2), which has a sectional area of less than 10.sup.-5 cm.sup.2, connected to a lead wire (5) at one end of an insulative capillary (1) and inscribed in the capillary (1), and providing a coating film (7) at another end, which is open, of the capillary (1) by an electrolytic polymerization process.The film-coated sensor obtained has a surface which is uniform, the film coating is easy to control, and since the sensor is not readily susceptible to flow of a specimen fluid, there is little drift and response is quick. Owing to its small size, the sensor is capable of measuring very small samples and of performing measurement upon being directly inserted into a living body or tissue.The sensor can be used also as an enzyme sensor by coating the surface of the film-coated sensor with a fixing enzyme film.

Abstract: An electrolytic sensor is set forth for measuring the amounts of an ionic and of a vaporous species in a liquid. The system has an electrode sensitive to an ionic species and another electrode sensitive to a vaporous species. A unitary membrane covers the electrodes and the requisite electrolyte with the membrane being permeable to the vaporous species, impermeable to the liquid and having dispersed in it an ionophore which senses the ionic species via selective transfer into the membrane of a quantity of the ionic species determined by the concentration of the ionic species in the liquid. Such quantities as hydrogen ion concentration, carbon dioxide concentration and oxygen concentration can be determined by a single electrolytic cell structure.

Abstract: The invention relates to a reference electrode for chemical sensors based on ion-selective field-effect transistors (CHEMFETs) in an electrolyte/insulator/semiconductor system. The reference electrode is essentially composed of a polyglutamate-coated insulator/semiconductor substrate or of a polyglutamate-coated phthalocyaninato-polysiloxane polymer film applied to an insulator/semiconductor substrate.

Abstract: Phosphate ion-sensitive composition and ion-selective electrode are disclosed incorporating an ionophore having the formula:R.sub.1 --X (a)orX--Z--X (b)wherein R.sub.1 is H or a hydrophobic substituent, Z is a spacing unit and X is represented by the formula: ##STR1## wherein n=0 or 1 and R.sub.2 and R'.sub.2 are independently selected from the group consisting of CH.sub.2, C(O) or C(S).

Abstract: A heavy metal-free composition and its method of use in an ion selective electrode-based assay are disclosed. The heavy metal-free composition includes a borate compound and an alkalinity adjusting compound, and is used to dilute a test sample; buffer the test sample; and substantially reduce the effects of interferents present in the test sample on the ion selective electrode-based assay. The heavy metal-free composition and its method of use are especially useful in an ion selective electrode-based assay for carbonate ion concentration in a test sample, like blood serum, blood plasma, urine or cerebrospinal fluid.

Abstract: An electrode for a coulometric type of electrochemical detector, comprising a porous carbon product having the following physical properties (1) to (3):(1) an average pore size in the range of 5 to 70 .mu.m,(2) a specific surface area in the range of 0.1 to 3 m.sup.2 /g, as determined by the BET method, and(3) a stack thickness of crystallite (Lc(002)) of 40 .ANG. or less, as determined by X-ray diffractometry.

Abstract: Enzyme electrodes are disclosed consisting essentially of a uniform homogeneous layer of a finely divided platinum group metal or oxide, preferably preadsorbed onto the surface of an activated carbon or grapite powder, and deposited from suspension upon the surface of an electrically conductive substrate and in admixture with an enzyme and optionally a water soluble or water-dispersible binder. Preferably the enzyme electrodes are produced by coating the substrate with a suspension of the enzyme, the finely divided platinum group metal, and if present the carbon or graphite powder and binder, and drying at a temperature below that at which the enzyme is deactivated.

Abstract: A description is given, together with relative preparation processes, of a sensor containing an immunochemical membrane and a device of EOS or CHEMFET type containing surface silicon oxide adhering to said membrane via a polysiloxane matrix, characterized in that the immunochemical membrane is formed from a functionalized antigen or from the same functionalized antigen bonded to a protein, said immunochemical membrane being bonded chemically to the polysiloxane matrix by functional groups present on the same antigen or by bifunctional coupling agents.

Abstract: A portion of a board (1) on which copper wiring is printed is provided with a carbon coating, the board (1) and lead wires (2) are joined by solder (3), the portion having the solder (3) is insulated with a silicone resin (4), and the carbon-coated printed wiring portion (10a) is successively coated with a redox layer (11) obtained by electro-oxidation of 2,6 xylenol and an ion-selective layer (12), thereby forming an ion sensor (20).Since the ion sensor can be formed on a printed wiring board, various devices which include an ion sensor can readily be fabricated on a board.

Abstract: An electrochemical cell is formed by immersing an electrochemical ion sensor and a reference electrode into a solution of interest, the electrochemical ion sensor exhibiting ion selectivity with respect to an ion of interest and having a high electrode resistance. A current which flows through the electrochemical cell is measured while the potential of the electrochemical ion sensor is held to a constant potential with respect to the reference electrode. The current so obtained are proportional to the logarithm value of the concentration of the ion.

Abstract: An ion sensor of the type wherein a specific type of ion in an aqueous solution is measured by potential response. The sensor includes a conductor base, and a reversible redox polymer film formed directly on a surface of said conductor base. An ion carrier film is formed directly on a surface of said redox polymer film. The carrier film contains an ion carrier substance for allowing the specific type of ions to permeate from the aqueous solution to said polymer film.