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: A sensor which may be immersed in a fluid to measure the pH and the ORP potential of the fluid is taught. The sensor has three solid state electrodes, a pH sensing electrode, a reference electrode and an ORP potential sensing electrode, which extend from a fluid-tight enclosure. The enclosure further contains a display means for indicating the pH measurement and the ORP potential measurement.

Abstract: A plant operational status monitoring supervisory system comprising; means for extracting information directly relating to water quality of an objective portion consecutively for a period of time by means of an electrochemical water quality sensor installed in an objective portion to monitor in-situ in a plant; means for evaluating water quality based on thus extracted information; means for comparing an obtained water quality evaluation result with a reference value for a predetermined plant operation procedure; and means for displaying or storing necessary portion out of said comparison results; is disclosed.

Abstract: A device for automatically and continually monitoring the pH characteristic of a water based printing ink which uses a housing for a pH probe, which housing is placed in a flow line through which such ink is flowing, the housing having a main channel for ink flow and a recessed channel into which a pH probe member is inserted. A baffle is provided to direct a portion the flowing ink into the recessed channel in contact with the probe to continually monitor the pH of the flowing ink. A portion of the ink remains in the recessed channel when ink flow is stopped so that the probe surface is covered by the remaining ink and cannot dry out and reduce or destroy the effectiveness of the probe.

Abstract: The present invention comprises an electrochemical metering apparatus that provides for convenient storage and presentation of the analytical electrode, simple assembly, and two calibration modes. The apparatus includes an electrode storage and presentation assembly that permits the user to introduce the electrode into a sample solution while simultaneously observing the meter's output, and store the electrode when not in use. All structural components are intended to fit together with interlocking tabs and windows. A serial port fits within the construction of the main housing without the need for bolts, and battery clips that depend directly from the circuit board obviate the need for wiring connections. The present invention also features two calibration modes. A "segment addition" mode permits separation of the voltage/concentration curve into individually plotted regions, the number of which depends on the number of reference solutions used in the calibration procedure.

Abstract: Batch injection analysis comprises apparatus and method for injecting and transporting analytes toward a detector immersed in a confined, inert electrolyte. Passage of the analyte over the detector surface provides measurement of sample concentrations. Detectors normally comprise selective electrodes, such as biologically or chemically modified surfaces, ion-selective probes, optical or thermal devices, thus eliminating conduits, valves, and pumps.

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: A device for in situ cleaning a fouled membrane of a sensor disposed in an aqueous process solution includes a first electrolysis electrode disposed in the process solution immediately adjacent the membrane, a second electrolysis electrode disposed in the process solution and spaced apart from the first electrolysis electrode, and a controllable power source for passing a current between said first and second electrodes. The current produces a heavy concentration of ions at a surface of the fouled membrane. The polarity of the current is selectable to produce negative or positive ions for reacting to decompose deposited salts, or to scrub contaminates from the membrane surface.

Abstract: An analyzing apparatus for the purpose of analyzing samples of body fluids, comprising a sample feeding device and a measuring channel in which measuring probes are contained. In order to attain good reproducibility and uniform conditions of treatment of the samples the measuring channel is separated by means of a valve from a storage tank communicating with the sample feeding device.

Abstract: A pH sensor includes a unitary cylindrical semi-porous plug which is formed with a central bore and is also formed with a cavity near a first end of the plug. A pH electrode is positioned in the central bore and extends outwardly from the second end of the plug for contacting a specimen fluid, and a reference electrode is positioned in the cavity. The plug is saturated with an electrolyte to establish electrochemical conductivity between the reference electrode and specimen fluid. To prevent ions from the specimen fluid from migrating through the plug and contaminating the reference electrode, a plurality of notches are radially machined part way through the plug and filled with ion-impermeable epoxy. The notches are preferably oriented at oblique angles relative to the axis of the plug to form "dead end" ion traps that will immobilize and impede a substantial proportion of contaminating ions, thus prolonging the life of the electrode.

Abstract: A reference electrode is formed of lead, zinc, tin, indium, cadmium, magnesium, or any alloy thereof. A pair of electrodes comprising the reference electrode and a responding electrode made of a conductive solid, when placed in oil, develop a potential difference varying with the acidity or basicity of the oil and thus enable the efficient determination of the acidity or basicity.

Abstract: In connection with a method for generating a constant derivation potential in analytical chemistry by means of a pH measuring chain containing a reference electrode, in particular for a pH test electrode for use in the meat-processing industry or for measurements in semi-solid substances such as cheese, pastes, in which for carrying out the measurement at least the pH measuring electrode is introduced into the medium to be measured by a corresponding movement, it is proposed that every time the pH measuring electrode is introduced into the medium to be measured, the electrolyte solution of the reference electrode, which is to be brought into contact with the medium to be measured via a diaphragm, be compressed whereby the diaphragm of the reference electrode, which gets into contact at least with the outer surface of the medium to be measured, is subjected to a cleaning action due to the pressure rise in the electrolyte solution occurring simultaneously with such compression.

Abstract: An apparatus and method for measuring the buffering capacity of a fluid which utilizes a pH electrode that is positioned at the surface of a smooth metal working electrode. Measured changes in pH of the metal-water interface at known potentials which are applied to the working electrode are used to calculate the fluid buffering capacity.

Abstract: A method for analyzing water or other liquid, in particular rain water, comprises the steps of providing a collector comprising at least first and second volumetric cells and a mechanism for causing water to flow selectively into the cells and for causing water to flow selectively from the cells. Water is caused to flow into a first one of the cells while it is prevented from flowing into the other one of the cells. The water collected in the first cell is caused to flow to a property determining cell when the first cell has been filled to a predetermined volume, and simultaneously water is prevented from flowing into the first cell while it is now permitted to flow into the second volumetric cell. The water collected in the second cell is then permitted to flow to a property determining cell when the second cell has been filled to a predetermined volume, and simultaneously the water is prevented from flowing to the second cell while it is now permitted to flow to the first cell.

Abstract: A luminescent probe complex for measuring pH comprising, polypyridine ligands having ion dissociable substituents on their carbon rings and a transition metal ion selected from the elements of the VIII group of the periodic table.Also disclosed is a luminescent probe membrane for measuring pH wherein the probe complex is contained in a macromolecular membrane. Further disclosed is a device for measuring pH wherein the probe membrane is immobilized at the tip of an optical fiber.A method for measuring pH using the above are also disclosed. The present invention enables measurement of pH of microenvironments.

Abstract: A solid state pH sensor having an indicator electrode of metal/metal oxide and a reference electrode of metal/metal salt applied to electrically conductive conductors, such as electrically conductive cermet conductors and electrically conductive metal pins, imbedded in an electrically non-conductive substrate, such as electrically non-conductive ceramic substrates including S-glass substrates. 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 electrically conductive conductor imbedded therein. These indicator or reference electrodes may be utilized with each other or with prior art indicator or reference electrodes.

Abstract: The present invention comprises an electrochemical metering apparatus that provides for convenient storage and presentation of the analytical electrode, simple assembly, and two calibration modes. The apparatus includes an electrode storage and presentation assembly that permits the user to introduce the electrode into a sample solution while simultaneously observing the meter's output, and store the electrode when not in use. All structural components are intended to fit together with interlocking tabs and windows. A serial port fits within the construction of the main housing without the need for bolts, and battery clips that depend directly from the circuit board obviate the need for wiring connections. The present invention also features two calibration modes. A "segment addition" mode permits separation of the voltage/concentration curve into individually plotted regions, the number of which depends on the number of reference solutions used in the calibration procedure.

Abstract: Precalibrated, disposable electrochemical sensing devices can be constructed so as to utilize a housing shaped so as to internally include at least two separate half cells, one of which is capable of serving as a reference half cell and the other of which is capable of serving as a sensing half cell. The housing is shaped so as to include a top depression capable of being used as a container which is in communication with the interiors of the half cells. The depression is capable of holding for a sample to be analyzed using the device. The housing is preferably mounted on a board which is capable of being plugged into a female socket. This board carries electrodes which are connected to electrodes in the half cells.

Abstract: A safe failure ion selective combination electrode in which a signal unit provides a signal if combination electrode output falls outside a predetermined range.

Abstract: A sensor system for determining the pH or carbon dioxide concentration of a liquid medium comprising, in combination, a pH-insensitive fluorescent indicator and a PH-sensitive fluorescent indicator which act in concert or a single fluorescence indicator which emits fluorescent signals of different wavelengths in different carriers, which system(s) produce diverging signals, the ratio of which provides an accurate and stable determination of the parameter being measured. A method for determining pH and CO.sub.2 concentration is also disclosed.

Abstract: A pH-measuring system using a Barnacle electrode (e.g. Ni--NiO.sub.2) in an electrolyte to abstract hydrogen from a metal electrode in the same electrolyte, and produces data as to the time t.sub.max required for the current density at the exposed surface of the metal electrode to reach its maximum value j.sub.max after an external circuit between the two electrodes is closed. From t.sub.max and j.sub.max the pH in the bulk of the electrolytes is determined, for display or for control purposes.

Abstract: The surface of an electrically conductive substrate (1) is provided with a redox layer (5) by an electrolytic polymerization process, and the surface of the resulting member is further provided with an ion carrier membrane (6) which includes polyvinyl chloride, a plasticizer and an ion carrier, thereby forming an ion sensor. Used as the plasticizer is one selected from among phthalate plasticizers, maleate plasticizers, adipate plasticizers, carboxylate plasticizers and polycaprolactone plasticizers, or one selected from among plasticizers comprising modified ethylene-- vinyl acetate copolymer. The ion sensor obtained has low solubility in the plasticizer of the redox layer and therefore is highly stable. Since the ion sensor has little toxicity, it can be used in vivo.

Abstract: A method for measuring trace amounts of analyte substance(s), which utilize a pH electrode is disclosed. This method is by far simpler than conventional optical detecting systems. The apparatus for practicing the method is also disclosed. By the use of pH electrode, the apparatus is compact, inexpensive and easy to operate, and hence usable in small-size and medium-size hospitals or clinical laboratories and by patient's bedside.

Abstract: Monitoring acidity at the ppm level in phenol-acetone-cumene process streams on a continuous basis is accomplished with a standard hydrogen electrode and a double-junction reference electrode with an external body solution comprising phenol, acetone, water, and a tetraalkyl- or tetraarylammonium salt, which provide a time invariant voltage without the necessity of adding any external solvent to the process stream. Phenol/acetone ratios can be varied from 1:10 to 10:1 which encompass the 1:1 ratio produced by the phenol-acetone process. A direct correlation of the electrode potential with the acidity of the medium is obtained. With the aqueous mixture isolated by a low flow ceramic junction from the process stream, no contamination of the process stream occurs.

Abstract: A probe (14) comprises a tubular electrical conductor (15) supported by a sleeve of insulating material (16). The two ends of the conductor are connected to couplings (23, 24) for the circulation of a reducing gas through the entire length of the conductor, as well as to an electric circuit (20) kept at a constant voltage and hence permitting measurement of the resistance in a segment (15c) of the conductor which is exposed to the atmosphere of a furnace, the resistivity of the segment varying as a function of the carbon content of the wall of the conductor.

Abstract: An electrode, preferably of a conductive polymer, has on its surface, preferably over all of its surface, an ion exchange material, preferably of significant thickness. Such a coated electrode may be used for sensing the presence or measuring the concentration of an ionic species, or for removal from or release of an ionic species into an electrode.

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: A sensor for the determination of the concentration of a dissolved substance in an aqueous medium comprising an optical fiber having on the distal end thereof an adherent, water-insoluble organic polymer having a plurality of fluorescent organic substituents, which may be the same or different, covalently bonded to said polymer through ester or amide linkages.

Abstract: An apparatus for the detection of chemical equalization processes in aqueous solutions, in particular for the determination of pH values and/or redox potentials, is described. The apparatus, a so-called interchangeable probe, includes an essentially cylindrical probe body, with a calibrating chamber and with an immersion pipe axially displaceable in a bore of the probe body and having at its front end a protective cylinder, the area adjacent to the immersion pipe being perforated in a basket-like manner. An electrode is set into the immersion pipe with the head of the electrode being located within the basket like perforated area of the protective cylinder. An annular gap between the immersion pipe and the inner wall of the probe body is sealed by at least three gaskets, located on the inner wall of the probe body.

Abstract: An electrode for measuring the activity of ionic species. The electrode comprises a material which is chemically sensitive to at least one ionic species. The material comprises an insulating component and a conductive component of lower resistivity than the insulating component. The insulating component has a density of proton binding sites sufficiently large to be sensitive to the ionic species. The conductive component comprises particles, the size of which are sufficiently small to modify the bulk conductive properties such that the susceptibility of the particles to redox interference in the operation of the electrode is decreased, while maintaining sufficient conductivity to operate in Faradaic electrode configurations. Illustratively, the insulating component is tantalum oxide, zirconium oxide or aluminum oxide and the conductive component is iridium, platinum, ruthenium, palladium, rhodium or osmium oxide.

Abstract: An electrode device for the determination of the partial pressure of CO.sub.2, Pco.sub.2, in particular an electrode device for transcutaneous determination of Pco.sub.2.The interior electrolyte of the electrode device is adapted to the exterior electrolyte in such a manner that the potential difference measured over the exterior reference electrode and the interior reference electrode is substantially temperature-independent with a temperature dependence for the CO.sub.2 partial pressure determination in the range of -1%/.degree.C.-+1%.degree.C.The interior electrolyte preferably contains a pH-buffer system based on phenyl phosphonic acid.

Abstract: In a method for the electrical measurement of the concentration of acids a measurement electrode (11) consisting at least predominantly of crystalline graphite is arranged in an acid (12) having anions which form graphite intercalation compounds with graphite. The measurement electrode (11) is then intercalated by generating in the measurement electrode (11), at a variable positive potential, a current of such a size that the anions of the acids (12) can from graphite intercalation compounds with the graphite. The current is maintained until the intercalation compounds have formed at the surface. The potential at the measurement electrode (11) is then measured and used as a measure for the acid concentration. The measurement electrode (11) is subsequently deintercalated again.

Abstract: The present invention provides an electrolyte solution, a reference half-cell, and a complete electrochemical cell particularly useful in making pH measurements of industrial and waste streams having suspended solids or high salt concentrations. An electrolyte solution containing water; at least one lithium salt, e.g. lithium chloride; and at least one ionic species at a constant electrochemical potential, e.g. silver chloride, buffered to a constant pH, is used in the half-cell and complete electrochemical cell. A high concentration of total ions in the electrolyte solution provides a flow direction out of the cell into the test stream, thereby reducing or eliminating the problems of cell contamination and plugging previously encountered. A second solution of high total ionic concentration, e.g. lithium nitrate, is also provided as a salt bridge in the cells to further insure diffusion of the cell electrolyte solution out into the stream being tested.

Abstract: In a sheet type reference electrode having a gelatinized internal solution, a liquid junction surface of the gelatinized internal solution is coated with a hydrophilic porous thin film. Alternatively, a liquid junction member contacts the gelatinized internal solution and is coated with a hydrophilic porous thin film. In either event, the thin film controls the diffusion of ions from the gelatinized internal solution. A liquid junction portion is also provided by impregnating a chemically stabilized, hydrophilic, high molecular porous material with a gelatinized composition which remains wet.

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: A fiber-optic probe for measuring the partial pressure of CO.sub.2 in a medium includes a single optical fiber having a distal end; a mirror; a hydrolyzed dye/gel polymer, the dye being in contact with a bicarbonate solution; a solution permeable membrane covering the fiber distal end, hydrogel and mirror; and a gas-permeable membrane covering the solution permeable membrane.

Abstract: Novel microelectrochemical devices are provided which consist of closely spaced microelectrodes coated with metal ion based inorganic redox active material such as oxides or mixed oxides of any of the following transition metals: W, Ni, Ru, Co, Rh, Ir, Nb, Mo, V, or any other metal that undergoes a change in electrical conductivity upon electrochemical oxidation or reduction, in contact with an electrolyte. Additionally, other metal based redox materials whose conductivity changes as a function of the movement of ions into or out of the material can be used in the construction of microelectronic devices, for example, Prussian Blue, Fe.sub.4 [Fe(CH).sub.6 ].sub.3."Metal ion-based microelectrochemical devices" encompasses all devices based on an inorganic redox active material which incorporate an active "gate" region or "channel", or exhibit rectification.

Abstract: Electrochemical devices constructed according to the present invention can be used to convert an ion flux into an electric current for determination of ion concentration. The devices are operated without the need for a reference electrode and are specific based on known ion transfer agents. Operation of the devices involves the use of pairs of electrodes modified with electroactive redox materials overlaid with ion selective coatings. An applied potential between a pair of appropriately modified electrodes results in the flow of an electric current between the electrodes which is dependent on the concentration of the ion to be sensed.Devices constructed by combining electrodes overlaid with electroactive polymers and different ion selective films allow simultaneous determination of diverse ions. For example, these devices are useful for measuring the concentration of total cations, total anions, H.sup.+, Li.sup.+, K.sup.+, Ca.sup.2+, Na.sup.+, HCO.sub.3.sup.-, Cl.sup.

Abstract: A reference electrode, optionally in combination with a measuring electrode to form a combination electrode, is disclosed in which the salt bridge comprises anionic and cationic ion exchange polymer. This polymer may be a diaphragm forming the liquid junction structure of the reference electrode. Polymer is preferably a mixture of anionic and cationic ion exchange polymer which may be either water insoluble or water soluble and is preferably converted to a form which binds equitransferent ions. When the polymer is substantially insoluble, a water-soluble thickener polymer may be incorporated in the polymer composition. Methods of measuring pH using the electrodes of the invention are also disclosed, particularly in high purity deionized water.

Abstract: An electrochemical cell comprising two electrodes, wherein one of said electrodes is suitable for use as a reference electrode in electrochemical measurements, said device comprising (a) a capillary fill cell capable of receiving a small volume of aqueous sample liquid, said cell incorporating (b) a redox electrode located within said capillary fill cell, and (c) a reagent layer comprising quinhydrone located in said cell in a dry adherent water-soluble layer adherent to an inner surface of said cell opposite to or overlying said redox electrode and capable of dissolving during use in aqueous sample liquid in the region of said redox electrode.

Abstract: A device capable of being mounted in a small opening in a reactor vessel, after having been inserted through a manway, which permits the continuous sampling of the contents of the reactor during a reaction, and continuous monitoring of the pH factor or other characteristic of interest. Electrical probe replacement is possible without disconnecting the device from the reactor vessel, and requires only a minimum of down time.

Abstract: A porous composite membrane comprises a base membrane of high mechanical strength and a coating of a hydrophilic polymer on the surface of the membrane and on the walls of the pores. The invention includes a method to prepare the membrane and a biosensor including the membrane.

Abstract: (a) Apparatus for regulating the concentration of an oxidizing solution, particularly a solution containing disinfecting molecules.(b) Apparatus characterized in that it comprises a secondary pipe (6) branched to a main pipe (1) upstream of a readjustment pipe (5) to which is fitted a measuring cell (2), as well as an addition pipe (12) connected to a reservoir (8) containing an adapting solution (7).

Abstract: A process control system for a filter press membrane electrochemical cell is provided that utilizes a microcomputer for multi-tasking functions to concurrently execute four programs to control the cell operation and self-correct out-of-tolerance conditions or shut cell operation down if not corrected within the allotted time period. A core process control program intercommunicates with a timer program, an alarm monitoring program and at least one sequence program in the process control system.

Abstract: An efficient electrolytic recovery system, having several safety mechanisms, for recovering precious metals from a liquid medium is described. The system includes at least oen electrolysis cell unit having a plurality of reticulate metal foam cathodes. The system of the invention will efficiently recover such precious metals as Au, Ag and Pt. The system may also include a pH adjust means and a means for oxidizing cyanide in the liquid medium.

Abstract: A dual lumen CO.sub.2 catheter is formed of medical grade dual lumen silicone rubber tubing which has been impregnated with tridodecyl amine. The silicone tubing is gas permeable, and an external reference electrode is used to monitor the potential across the impregnated outer wall of the dual lumen tubing as a function of pH. The analyte to be monitored is selected from the group consisting of CO.sub.2, NH.sub.3, SO.sub.2, NO.sub.2, H.sub.2 S, and HCN, the internal reference and electrolyte solutions contained in the lumens being selected in response to the particular analyte desired to be monitored. In a CO.sub.2 embodiment, the reference lumen is filled with a buffered internal reference solution, and the response lumen is filled with a bicarbonate filling solution. Reference wires formed of Ag/AgCl in respective ones of the lumens forms the internal electrodes.

Abstract: A combination pH and CO.sub.2 sensor employs separate sensors. Each sensor has a wire with an electrochemically active layer, an electrolyte layer and a membrane between the electrolyte layer and the fluid to be tested. Each electrolyte layer is constructed of a dried residue which can be easily stored and which must be rehydrated prior to the first use. The electrolyte layer in the pH sensor when hydrated forms an aqueous solution buffered against changes in pH due to changes in the dissolved CO.sub.2 concentration and is preferably formed of 2-(n-morpholino) ethanesulfonic acid, 2-(n-morpholino) ethanesulfonic acid - sodium salt and potassium chloride. The electrolyte layer in the CO.sub.2 sensor when hydrated forms an aqueous solution having bicarbonate ions and is preferably formed of polyvinyl alcohol, sodium chloride and sodium bicarbonate. The electrical potential at the pH sensor is proportional to the pH of the fluid. The electrical potential difference between the CO.sub.

Abstract: A junction-type metal/metal oxide solid state indicator electrode wherein the sensing portion of the electrode is coated with a perfluorocarbon copolymer, and a pH sensor made of the indicator electrode and a reference electrode.

Abstract: Partition membranes which are permeable to blood electrolytes fabricated from crosslinked polyetherurethane compositions having from 20 to 50% hard segments. The membranes absorb from 50 to 120% of their dry weight of water and have electrolyte diffusion constants of up to 1.times.10.sup.-6 cm.sup.2 /sec. The membranes are included in electrochemical, fiber optic and solid state blood electrolyte sensors to provide blood compatible surfaces and to ensure that blood components deleterious to analysis of electrolyte in the blood remain separated from the sensing elements.