Abstract: New solid state pH and sodium ion sensitive metal-oxide-type compositions, sensors and methods are disclosed. Performance thereof was demonstrated at ambient temperature with single crystals of several molybdenum bronzes (i.e. Na.sub.0.9 Mo.sub.6 O.sub.17, Li.sub.0.9 Mo.sub.6 O.sub.17, Li.sub.0.33 MoO.sub.3 and K.sub.0.3 MoO.sub.3) The pH sensors with Na-molybdenum-oxide bronzes show near ideal Nernstian behavior in the pH range 3-9. The response is not affected by the direction of the pH change.

Abstract: This invention pertains to fluorophoric compositions of a 7-amino-coumarin derivative and methods of their use for enhancing visualization of various constituents of ion selective electrodes.

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

Abstract: A new substrate for the construction of solid internal contact ion-selective electrode comprising a conductive and porous carbon matrix is described. The well-defined (i.e., fixed) interfacial potential between the organic electroactive phase and the internal reference element, coupled with the electrode's very slow change from water activity at the internal reference element, supports the well-behaved and reproducible electrode operation. Solid contact sensors for two different ions were constructed, and their potentiometric behavior was compared with their symmetric counterparts. The potentiometric response was monitored over a period of one month with excellent results for drift, base line stability, response time, selectivity, and detection limit.

Abstract: An efficient method for the microfabrication of electronic devices which have been adapted for the analyses of biologically significant analyte species is described. The techniques of the present invention allow for close control over the dimensional features of the various components and layers established on a suitable substrate. Such control extends to those parts of the devices which incorporate the biological components which enable these devices to function as biological sensors. The materials and methods disclosed herein thus provide an effective means for the mass production of uniform wholly microfabricated biosensors. Various embodiments of the devices themselves are described herein which are especially suited for real time analyses of biological samples in a clinical setting. In particular, the present invention describes assays which can be performed using certain ligand/ligand receptor-based biosensor embodiments.

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

Abstract: A sensor for hydrogen is disclosed comprising an electrically insulating substrate carrying a thin amorphous film of co-deposited nickel and zirconium and an overlying film of palladium wherein during the operation of the sensor, hydrogen in a sample gas is dissociated on the palladium film and diffuses into the nickel-zirconium film to change its electrical resistance in proportion to the amount of hydrogen in the sample to be analyzed.

Abstract: In a method for calibration of a pH measuring element whose ion-permeable, hydrophilic polymer layer is brought into contact with an aqueous solution prior to calibration, the aqueous solution is displaced or replaced by a gaseous calibrating medium, and residues of the aqueous solution remaining in the ion-permeable polymer layer. The gaseous calibrating medium contains a known amount of at least one component which is acid or basic in aqueous solution which reacts with the remaining residues of the aqueous solution in the polymer layer, such that a defined pH value is established in the polymer layer, which is employed for calibration of the measuring element.

Abstract: A solid state chemical sensing device is described in which a chemically sensitive electrode, and at least one diamond film are deposited on a conductive or insulating substrate. The device forms a sensing structure in which conduction of current through the device in the presence of a target chemical is dominated by space charged limited current, thereby providing enhanced sensitivity and selectivity.

Abstract: Ion selective ceramic membrane with high proton conductivity, which membrane is formed of lanthanide phosphate being doped with one or more metals Me from Group IIA of the Periodic Table and having a composition:Ln.sub.1-x Me.sub.x PO.sub.4whereinLn is lanthanum, cerium, praseodymium, neodymium, samarium, europium and/or gadolinium; and0<x.ltoreq.0.5.

Abstract: An oxygen concentration detector includes a one-end closed cylindrical oxygen sensing element having an inside electrode, outside electrode provided on the inner side and outer side respectively, an electrode protecting layer made up of ceramics porous member provided further outside the outside electrode, and a trap layer 1 of ceramics porous member having a surface roughness of 20 to 100 .mu.m measured according to a 10 point mean roughness measurement and provided outside the electrode protecting layer is employed. By dipping the to-be-detected gas side surface of an oxygen sensing element into a slurry with coarse heat-resisting metal oxide particles, 2 to 50 .mu.m in average grain size, dispersed, depositing the slurry on the surface of a protective layer of an oxygen sensor element, thereafter drying and baking the deposit, a porous poisonous substance trap layer, 10 to 500 .mu.m thick, is formed.

Abstract: This invention relates to a pH measuring electrode having a sensor film which is sensitive to a hydrogen ion (H.sup.+) in the solution. The pH measuring electrode of this invention has a sensor film of a metal oxide deposited on an electrically insulative ceramics substrate so that the sensor film can be very miniaturized in its size. Therefore, the entire pH measuring electrode can be made considerably small and simple in construction. Also, this invention provides another pH measuring electrode which further includes a porous film of an insulation material coated on the surface of the metal oxide sensor film so that the sensor film is not affected by any coexistent substances.

Abstract: The service life of a conventional free fluoride ion sensitive electrode can be improved by shielding the outer casing of the conventional electrode against contact with the liquid composition in which the free fluoride ions concentration is to be measured, particularly when the solution is a hot acid solution containing surfactants and/or oxidizing agents, such as is normally used for cleaning aluminum beverage containers or providing a protective surface treatment to aluminum surfaces.

Abstract: A solid state ion-selective electrode device to detect a selected ion species in solution an electrode consisting of a homogeneous solid mixture. The mixture is a solid electrolyte composition possessing ionic conductivity and polyvinyl chloride, and optionally graphite. The electrode is substantially free of metallic silver. An electrical connection operates as a contact between the electrode device and a reference source. Methods for detecting the selected ion species in solutions, such as biological samples utilizing the above described electrodes, are also disclosed.

Abstract: A member has a solid carrier and a thin oxide layer which is arranged thereon and consists of iridium oxide and/or possibly at least one oxide of at least one other metal belonging to the fifth or sixth period and to one of the subgroups 5b, 6b, 7b and 8 of the Periodic Table of chemical elements and/or zirconium oxide. The oxide layer is monocrystalline and therefore very stable. The member can serve, for example, for the formation of at least one electrode which serves as a proton donor and/or proton acceptor and/or for the measurement and/or change of the pH value and/or for a coulometric measurement or for holding biologically active molecules and at the same time as an electrode and/or optical sensor.

Abstract: Novel calibration solutions are provided which are useful, for example, with sensor assemblies used for analysis of CO.sub.2, and optionally, for concurrent analysis of O.sub.2, especially in combination infusion fluid delivery/blood chemistry analysis systems which include a sensor assembly with each of the assembly electrodes mounted in an electrode cavity in the assembly. The analysis system used in the practice of the present invention typically includes provision for delivering infusion fluid and measuring blood chemistry during reinfusion of the physiological fluid at approximately the same flow rates. The invention calibration solutions are useful for calibrating an array of sensors capable of simultaneously measuring a number of blood chemistry parameters, including the partial pressures (tensions) of carbon dioxide and oxygen, pH (hydrogen ion), sodium, potassium, ionized calcium, ionized magnesium, chloride, glucose, lactate and hematocrit, in body fluids.

Abstract: A miniaturized oxygen electrode comprising: an electrically insulating substrate; an electrolyte-containing material disposed on the substrate to form an electrolyte solution when water is introduced thereto; a set of component electrodes disposed on the substrate and connected with each other via the electrolyte-containing material; a gas-permeable membrane covering the electrolyte-containing material; the set of component electrodes including a cathode on which a reduction reaction of oxygen occurs and an anode as a counterpart of the cathode; the electrolyte-containing material being composed of a first layer and a second layer which are mutually connected, the first layer containing no electrolytes and being connected to the cathode and the second layer containing an electrolyte and being not connected to the cathode, the mutual connection of the first layer and the second layer being effected so that, during the water introduction and a subsequent holding, the electrolyte of the second layer diffuses to

Abstract: This invention relates to a pH measuring electrode having a sensor film which is sensitive to a hydrogen ion (H.sup.+) in the solution. The pH measuring electrode of this invention has a sensor film of a metal oxide deposited on an electrically insulative ceramics substrate so that the sensor film can be very miniaturized in its size. Therefore, the entire pH measuring electrode can be made considerably small and simple in construction. Also, this invention provides another pH measuring electrode which further includes a porous film of an insulation material coated on the surface of the metal oxide sensor film so that the sensor film is not affected by any coexistent substances.

Abstract: A nozzle-type analysis apparatus for sucking a sample solution in a sample vessel for analyzing the sample solution. A sample suction nozzle for sucking the sample solution stored in the sample vessel and a solution component sensor having a sensor forming portion formed integrally with a front end portion of the sample suction nozzle to be inserted into the sample vessel are provided. The integral structure of the sample suction nozzle and the solution component sensor has a size capable of being inserted into the sample vessel, the solution component sensor having a sensor output portion effected with a water-resistant insulation layer. A hydrophobic film is further formed on the surface of the sensor a coat treatment. A sample flow shut-out valve is disposed in the sample flow passage at a portion between the front end of the sample suction nozzle and the sensor forming portion of the solution component sensor.

Abstract: An ion sensor having an ion selectivity, which comprises an internal electrode of metal/metal salt, composed of an electroconductive layer of at least one metal and a layer of an insoluble salt of the metal in contact with the electroconductive layer, an ion selective membrane whose supporting membrane is composed of a hydrophobic polymer, and an intermediate layer capable of keeping water molecules, provided between the internal solid electrode and the ion selective membrane, where the organic compound having a water-keeping property is polymethylene glycol, polyethylene glycol or polypropylene glycol, each having a molecular weight of 200 to 600, and the inorganic compound having a water-keeping property is calcium chloride, gold chloride, magnesium perchlorate, magnesium fluoride or vanadium chloride dioxide, is suitable for analysis of specific ion species in a biological fluid with practically prolonged maintenance of properties of electrode.

Abstract: A miniaturized sensor component for measuring concentrations of substances in liquids comprises a support that contains cavities accommodating a membrane. The membrane is produced in situ by polymerization or by precipitation from a solution. An electric lead is either mechanically connected to or integrated into the membrane and is in contact with the membrane. The membrane support is a capillarized solid and the membrane is produced in the capillaries by impregnating the support with a liquid that subsequently either polymerizes or evaporates leaving a residue.

Abstract: An electrolyte composition for screen printing, comprising: an organic solvent; an inorganic salt in the form of a fine powder able to pass through a screen printing mesh, the salt powder being dispersed in the organic solvent; and polyvinyl pyrrolidone dissolved in the organic solvent. A miniaturized oxygen electrode having an oxygen sensing site filled with the electrolyte composition. A process for producing a miniaturized oxygen electrode, including a step of patterning or selectively removing an oxygen gas-permeable membrane at a pad region by removing or peeling off an underlying cover film formed thereunder.

Abstract: An efficient method for the microfabrication of electronic devices which have been adapted for the analyses of biologically significant analyte species is described. The techniques of the present invention allow for close control over the dimensional features of the various components and layers established on a suitable substrate. Such control extends to those parts of the devices which incorporate the biological components which enable these devices to function as biological sensors. The materials and methods disclosed herein thus provide an effective means for the mass production of uniform wholly microfabricated biosensors. Various embodiments of the devices themselves are described herein which are especially suited for real time analyses of biological samples in a clinical setting. In particular, the present invention describes assays which can be performed using certain ligand/ligand receptor-based biosensor embodiments.

Abstract: A novel series of chalcogenide glass compositions that are relatively highly selective for a specific ion in solution. When utilized as a sensing element for electrodes or similar analytical devices, a modified surface layer is formed on the surface of the glass in contact with the test solution. The surface layer being characterized by a surface ionic conductivity ranging from 10.sup.-7 to 10.sup.-2 S/cm, a diffusion coefficient ranging from 10.sup.-11 to 10.sup.-6 cm.sup.2 /s and having a ratio of electronic to ionic conductivity within the modified surface layer of not more than 1.0. Specific compositions having these unique morphology and transport properties are disclosed for the detection of cadmium, silver, thallium, mercury, copper and lead.

Abstract: A method of measuring the silver ion activity of a mixed halide solution or dispersion comprises measuring the potential difference between a silver halide coated silver electrode and a reference electrode immersed in the solution or dispersion. Prior to measuring the potential difference an electrical pulse is applied to the silver electrode which in a first phase electrochemically strips the electrode surface and in a second phase electrochemically coats the electrode with a silver halide having the halide ion ratio of the solution or dispersion.

Abstract: A method for the preparation of layered electrodes, including ultramicroelectrodes, through application of a thin film coating of an inorganic material to a conductor by use of chemical vapor deposition. The chemical vapor deposition techniques of the present invention provide a layered electrode that is efficiently and effectively manufactured in a standard reaction chamber at atmospheric pressure. The preferred conductors are carbon fibers and foams, and metal (platinum or gold) wires, meshes and foams. The precursors for the thin film deposition include those that yield thin-films of insulators, semiconductors, metals, and superconductors. During the chemical vapor deposition process, a thin film coating is formed on the conductor by the pyrolytic decomposition of the precursor vapor at the surface of the heated conductor. The hardness and rigidity of the thin film layer imparts durability and structure to the fragile and flexible conductors without significantly increasing the size of the device.

Abstract: An ion-selective electrode comprises, in order of enumerating from the measured-ion contact side: a solid electrolyte as an ion-sensitive membrane; an ionic bridge layer; and, an internal electrode. The bridge layer is prepared by mixing a salt mixture with an electrically conductive resin composition at a ratio of 1:2 to 3:1 in weight, determined after heat treatment. The salt mixture is prepared by mixing silver halide with sodium phosphate at a ratio of from 9:1 to 3:7 in weight. The electrode is very small in voltage fluctuation detected among products; easily downsized to be capable of measuring a very small amount of a sample solution; and useful in measuring activity of ion species such as Na-ion.

Abstract: An electrochemical sensor having multiple measuring zones (34) that are sequentially insulatable, disposed on the circumference of an insulating disc (1) and associated with each other by peripheral current collectors (16, 17) which extend radially inward up to central zones where they form contacts (23, 24) for a measuring apparatus. The disc-sensor also has a device (6) for rotating the disc, and guide marks for positioning (11) and for isolating (7) the measuring zones (34), and may be contained in a housing (40). The invention is useful in the quantitative analysis of glucose.

Abstract: A small sensor for an electrochemical measuring system composed of a measuring apparatus (50) having an electronic circuit (60), a connecting device (64), a positioning and advancing device (56, 57) and an eliminating device (59, 53). The apparatus is adapted to receive the sensor (40), which has a plurality of active, successively disposable measuring zones (34). The sensor has applications in the quantitative analysis of glucose in the blood.

Abstract: An improved electrode is described having a replaceable cap in which a crystal membrane is mechanically secured. Leakage around the crystal membrane is avoided. The cap can be easily and quickly replaced, as desired.

Abstract: The invention relates to a process for the determination of iodine in low concentration in a nitrate solution, particularly a uranyl nitrate solution.According to this process, to the sample to be determined is added a reducing agent such as ascorbic acid in order to maintain the iodine in the iodide state, followed by the measurement of the potential difference E.sub.1 between a selective iodide ion electrode (5) and a reference electrode (7), after which there is a successive addition of a first and a second iodide solution having known iodide concentrations and containing a reducing agent, accompanied by the measurement after each addition of the potential differences E.sub.2 and then E.sub.3 between the electrodes (5) and (7), followed by the calculation from E.sub.1, E.sub.2 and E.sub.3, the concentrations and volumes of the additions, the initial iodine concentration of the solution.

Abstract: A sensor for detecting a carbonic acid gas dissolved in body fluids has a laminated structure including an outer plate having a carbonic acid gas permeable window, a plate for a pH-electrode having a pH sensitive membrane, an intermediate plate having a cavity for accommodating an electrolyte, and a plate for a reference electrode. The plate for the pH-electrode is constituted in a manner that a pH sensitive membrane constituted by a membrane of an oxide of a platinum group metal is formed on an insulating substrate and the electrolyte contacts with the pH sensitive membrane in a groove. The pH sensitive membrane is disposed so as to oppose to the carbonic acid gas permeable window.

Abstract: An improved "all solid state" ion selective electrode device comprising a unique sensing element of triple-layer membrane construction. The first sensor layer of the sensing membrane comprising a solid electrolyte composition, the middle layer comprising a mixture of the aforesaid electrolyte composition and finely divided electronic conducting material, and the third contacting layer composed principally of the aforesaid electronic conducting material. The middle layer having a gradient of component concentration such that a substantial amount of the electrolyte composition is presented in the middle layer closest the first sensor layer and a substantial amount of the electronic conducting material is presented in the middle layer closest the third contacting layer.

Abstract: A nanostructured composite film comprising a plurality of nanostructured elements, wherein the nanostructured elements are either two-component sub-microscopic structures comprised of whiskers conformally coated with a conducting, preferentially catalytically active material or one component sub-microscopic structures comprised of a conducting preferentially catalytically active material, such that the nanostructured elements are embedded in an encapsulant, wherein the encapsulant can be a solid electrolyte. The composite film can be used as an electrode membrane in an electrochemical cell or sensor.

Abstract: The sensor apparatus of the present invention includes on a nonconducting substrate electrically conductive pathways leading to at least two analyte electrodes and one reference electrode. The analyte electrodes each have sensitivities for both analytes but each has a membrane and/or electrolyte that favors the conversion of ionic potential to electronic potential for a different analyte. The apparatus has an fluid circuit means for liquid contact between the electrodes so that electric signals can be sent by electric circuitry to an analyzing means.

Abstract: Novel calibration solutions are provided which are useful, for example, with sensor assemblies used for analysis of CO.sub.2, especially in combination infusion fluid delivery/blood chemistry analysis systems which include a sensor assembly with each of the assembly electrodes mounted in an electrode cavity in the assembly. The analysis system used in the practice of the present invention typically includes provision for delivering infusion fluid and measuring blood chemistry during reinfusion of the physiological fluid at approximately the same flow rates. The invention calibration solutions are useful for calibrating an array of sensors capable of simultaneously measuring a number of blood chemistry parameters, including the partial pressures (tensions) of carbon dioxide and oxygen, pH (hydrogen ion), sodium, potassium, ionized calcium, ionized magnesium, chloride, glucose, lactate and hematocrit, in body fluids.

Abstract: The glass electrode comprises a membrane of ion sensitive glass. The membrane comprises a composite material consisting of a matrix of ion sensitive glass and a dispersed filling material therein having higher tensile strength than the matrix. The membrane of the glass electrode is particularly resistant to mechanical stress and the glass electrode is i.a. applicable in a tc Pco.sub.2 electrode of the Severinghaus-type.

Abstract: A carbon dioxide gas detection element includes a solid electrolyte of a sodium ion conductor made of a ceramic/glass composite material.

Abstract: This invention relates to a pH measuring electrode having a sensor film which is sensitive to a hydrogen ion (H+) in the solution and method of manufacturing the same. The pH measuring electrode of this invention has a sensor film of a metal oxide deposited on an electrically conductive support so that the sensor film can be very miniaturized in its size. Therefore, the entire pH measuring electrode can be made considerably small and simple in construction. Also, this invention provides another pH measuring electrode which further includes a porous film of an insulation material coated on the surface of the metal oxide sensor film so that the sensor film is not affected by any coexistent substances.

Abstract: An electrochemical measuring cell has a three-electrode system including electrode, counter electrode and reference electrode in an electrolyte. The measuring cell has an additive promoting the electrochemical reaction and is selective and highly sensitive for the detection of hydrogen halides and also provides a stable measuring signal. A measuring cell of this kind has an additive of tetrachloroauric acid in the electrolyte for detecting hydrochloric acid with all electrodes being made of gold. The counter electrode is protected by a cation exchange membrane to provide a further improvement.

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: 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: 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: 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 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: Schottky diodes and gas sensors include a diamond layer having a Schottky contact thereon and an ohmic contact thereon, wherein the diamond layer includes a highly doped region adjacent the ohmic contact to provide a low resistance ohmic contact. Dramatically reduced frequency dependence of the capacitance/voltage characteristic of Schottky diodes and gas sensors formed thereby, compared to Schottky diodes and gas sensors which do not include the highly doped region adjacent the ohmic contact, is provided. The highly doped region is preferably boron doped at a concentration of at least 10.sup.20 atoms per cubic centimeter to form an ohmic contact with a contact resistance of less than 10.sup.-3 .OMEGA.-cm.sup.2. The ohmic contact is preferably a back contact on the face of the diamond layer opposite the Schottky contact.

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 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: Disclosed is an integrated ion sensor, which comprises at least one ion selective membrane sensitive to ions contained in a solution to be measured for detecting the concentration of the ions, a signal processing circuit for inputting a detected signal obtained by the ion selective membrane through a conductive member and fetching the detected signal through MOSFETs or the like included in an input stage to process the same, a reference electrode disposed in the measuring environment made by the solution to be measured and to be set to a predetermined voltage relationship between the reference electrode and the ion selective membrane, and a power supply having negative and positive terminals for supplying a driving power to the signal processing circuit through the terminals, one of the terminals being connected to the reference electrode, wherein the signal processing circuit is set to an active state at a voltage set to the reference electrode by controlling the threshold value of at least one of the MOSFET

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.