Abstract: An electrochemical sensor system and membrane and method thereof for increased accuracy and effective life of electrochemical and enzyme sensors.

Abstract: Semiconductor materials having a porous texture are modified with a recognition element and produce a photoluminescent response on exposure to electromagnetic radiation. The recognition elements, which can be selected from biomolecular, organic and inorganic moieties, interact with a target analyte to produce a modulated photoluminescent response, as compared with that of semiconductor materials modified with a recognition element only.

Abstract: Single-channel thin film devices and methods for using the same are provided. The subject devices comprise cis and trans chambers connected by an electrical communication means. At the cis end of the electrical communication means is a horizontal conical aperture sealed with a thin film that includes a single nanopore or channel. The devices further include a means for applying an electric field between the cis and trans chambers. The subject devices find use in applications in which the ionic current through a nanopore or channel is monitored, where such applications include the characterization of naturally occurring ion channels, the characterization of polymeric compounds, and the like.

Abstract: Semiconductor materials having a porous texture are modified with a recognition element and produce a photoluminescent response on exposure to electromagnetic radiation. The recognition elements, which can be selected from biomolecular, organic and inorganic moieties, interact with a target analyte to produce a modulated photoluminescent response, as compared with that of semiconductor materials modified with a recognition element only.

Abstract: There is provided a sample preparation device and method for preparing a sample of liquid for detection of impurities. First (40) and second (38) electrodes are provided, located for immersion in a liquid under test. A semipermeable membrane (42) is positioned to protect the first electrode (40) from a body of liquid under test (32). The semipermeable membrane allows the liquid under test to pass therethrough to reach the first electrode, while preventing solids carried in the liquid from reaching the first electrode, the first electrode being positioned to affect the liquid under test in the vicinity of a sensor (36). Particular embodiments feature a hydrophilic membrane to protect the electrodes from suspended solids in the sample, a thin electrode assembly to achieve a faster response and the addition of a heater for temperature control to achieve consistent detection conditions and improved anti-fouling properties.

Abstract: The present invention relates to a membrane for use in detecting the presence of an analyte. The membrane comprises an array of closely packed self-assembling amphiphilic molecules and a plurality of first and second receptor molecules, the first receptor molecules being reactive with one site on the analyte and second receptor molecules being reactive with another site on the analyte. The first receptor molecules are prevented from lateral diffusion within the membrane whilst the second receptor molecules are free to diffuse laterally within the membrane. The membrane is characterized in that the ratio of first receptor molecules to second receptor molecules is 10:1 or greater.

Abstract: There is provided a method of evaluating an electrode body impregnated with a non-aqueous electrolyte, comprising a positive electrode and a negative electrode wound or laminated with a separator inserted in between. The discharge limit of the electrode body is evaluated by means of affinity of the non-aqueous electrolyte for the separator. This method is capable of selecting an optimal combination between a separator and non-aqueous electrolyte and evaluating a discharge limit of the electrode body before finally manufacturing a lithium secondary cell.

Abstract: The present invention includes a method and sensor that is easy to assemble and can operate to effectively detect an air borne or exogenously introduced analyte. In one embodiment, the assembled sensor includes a top cap capable of receiving a first electrolyte and a bottom cap capable of receiving a second electrolyte. The assembled sensor also includes a flexible boot that holds together the top cap, the bottom cap and a membrane. The membrane is located between the first electrolyte and the second electrolyte and enables an electrical device to detect an analyte (e.g., hazardous chemical) which originally entered the sensor through a passage in the top cap and interacted with the membrane.

Abstract: An improved membrane based biosensor incorporates sensing and reference electrodes and a dc electrical potential produced by a counter electrode. The biosensor incorporates ionophores. The conductivity of the membrane is dependent on the presence or absence of an analyte. A functional reservoir exists between the sensing electrode and a lipid membrane deposited on the sensing electrode. The invention also includes the method of detecting the presence or absence of the analyte by use of the biosensor.

Abstract: A rotating electrode configuration lowers the detection limits of polyion-sensitive membrane electrodes. Planar potentiometric polycation and polyanion-sensitive membrane electrodes were prepared by incorporating tridodecylmethylammonium chloride and calcium dinonylnaphthalene sulfonate, respectively, into plasticized PVC or polyurethane membranes, and mounting discs of such films on an electrode body housed in a rotating disk electrode apparatus of the type used in voltammetry. Due to the unique non-equilibrium response mechanism of such sensors, rotation of the polyion-sensitive membrane electrodes at 5000 rpm resulted in an enhancement in the detection limits toward heparin (polyanion) and protamine (polycation) of at least 1 order of magnitude (to 0.01 U/ml for heparin; 0.02 &mgr;g/ml for protamine) over that observed when the EMF responses of the same electrodes were assessed using a stir-bar to achieve connective mass transport.

Abstract: A simple analytical method for determining antioxidant level in food product and body fluids such as urine is based on reduction of elemental iodine. The method adds an aqueous solution of iodine and an iodophor to the sample to be tested. Polyvinylpyrrolidone is a preferred iodophor. Antioxidant materials in the sample reduce the elemental iodine and the reaction is monitored by measuring either a decrease in iodine or an increase in iodide ion. A preferred method of practicing the invention is to measure the change in iodide ion with an ion selective electrode and an appropriate electronic meter. The method rapidly and inexpensively produces antioxidant measurements that are comparable to those produced by my more complex and cumbersome methods.

Abstract: Improved dry-operative ion-selective electrodes and their use are described. The dry-operative ion-selective electrodes include an internal reference electrode comprising a water-soluble salt dispersed in a polymer binder consisting essentially of a monomer having at least one carboxyl group and a hydrophobic monomer. The polymer provides reduced brittleness, good interlayer adhesion and high salt tolerance.

Abstract: The present invention provides a means to substantially decrease the pH bias that is commonly observed with pH data obtained using ion selective electrode (ISE) containing instruments that have a solvent polymeric membrane based ISE pH electrode. The pH bias is reduced by utilizing the discovery that the presence of protein in a liquid sample induces an apparent interference with the pH value.

Abstract: An apparatus for identifying an unknown reactive gas in a carrier gas, utilizing a sensor with a diffusion limited inlet. The apparatus includes a manifold of predetermined volume having an inlet and outlet, an inlet valve in the manifold inlet, an outlet valve in the manifold outlet, a gas detector in communication with the manifold, a diffusion barrier disposed between the manifold and the gas detector for limiting diffusion of gas from the manifold into the gas detector, means for opening and closing the inlet and outlet valves, means for detecting an output signal from the gas detector, means for determining a coefficient of diffusion for the reactive gas from the output signal, and means for identifying and quantifying the reactive gas from the determined coefficient of diffusion.

Abstract: A chemical sensor (1) for selectively detecting an analyte in a solution as described. The sensor comprises a flow-through chamber (2), a selective membrane (3), a transducer means (4), an inlet (5) for a liquid flow containing a recognition element, and an outlet (6). There is also described a method of selectively detecting an analyte in a solution, wherein a recognition element is contacted with the solution containing the analyte via a selective membrane, said contact resulting in a response detectable by transducer means. The recognition element is injected into a flow, the flow is passed into a flow-through chamber comprising a transducer means and the selective membrane, where it is contacted with the analyte passing from the solution outside the selective membrane, whereby the recognition element and the analyte interact to provide a signal which is detected by the transducer means.

Abstract: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region thereof which is capable of forming complexes with nitric oxide, for example, nitrosyl complexes. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, thereby leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. Most preferably, the electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are advantageously conditioned in saline solution at +675 mV for about two hours.

Abstract: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region capable of forming complexes with nitric oxide. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. The electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are pre-conditioned at a potential, or potentials, different than the working potential of the electrode, followed by further conditioning at the working potential. Direct response to nitric oxide has been observed for ruthenium electrodes at or below potentials about +675 mV vs. Ag/AgCl, while ruthenium electrodes paradoxical response to nitric oxide has been observed at potentials above +675 mV vs. Ag/Cl.

Abstract: Single-channel thin film devices and methods for using the same are provided. The subject devices comprise cis and trans chambers connected by an electrical communication means. At the cis end of the electrical communication means is a horizontal conical aperture sealed with a thin film that includes a single nanopore or channel. The devices further include a means for applying an electric field between the cis and trans chambers. The subject devices find use in applications in which the ionic current through a nanopore or channel is monitored where such applications include the characterization of naturally occurring ion channels, the characterization of polymeric compounds, and the like.

Abstract: A method and apparatus for identifying an unknown reactive gas in a carrier gas, utilizing a sensor with a diffusion limited inlet. After a signal is established for the carrier gas, a flow of the mixture of carrier gas and reactive gas is passed to the sensor and a steady state signal S is established. Then, the input to and output from the sensor are closed, and the steady state signal decays as a known volume of reactive gas is consumed. The decay curve of the signal is integrated to produce an integrated response .SIGMA., and the ratio S/.SIGMA. is proportional to the diffusion coefficient for the reactive gas. By comparing this ratio to the ratio for a known reactive gas, the identity of the unknown reactive gas can be determined.

Abstract: Apparatus for carrying out patch clamp technique utilized in studying the effect of certain materials on ion transfer channels in biological tissue, and more particularly patch clamp apparatus utilizing an autosampler, such as those utilized with HPLC apparatus, to provide high throughput, is disclosed. The invention additionally includes novel microperfusion chamber assemblies capable of utilizing only small amounts of material to be tested and only small amounts of liquid carrier, thereby enabling many tests to be completed in a short period of time. The invention more broadly relates to a novel electrophysiology drug handling and application set up for screening of chemical substances while providing high throughput and requiring only low volume of solutions and samples to be tested. The invention also comprises several novel procedures for utilizing the apparatus of the invention.

Abstract: The invention provides an electrochemical reaction wherein a controlled amount of a first reagent is generated electrochemically at an electrode in electrical contact with a solution of an electrochemically inert salt, comprising applying a suitable electrical potential to the electrode for a suitable time to generate a controlled amount of the first reagent by electrochemical reaction between the electrode and a species in solution producing a localized thin layer environment comprising the first reagent in the vicinity of the electrode; and monitoring the amount or presence of the first reagent or a further species produced in solution in response to production of the first reagent. The method invention thus involves generating the first reagent in situ at an electrode.

Abstract: An electrochemical test device is provided for determining the presence or concentration of an analyte in an aqueous fluid sample. The electrochemical test device includes a working electrode and a counter electrode made of an amorphous semiconductor material. The working electrode is overlaid with a reagent capable of reacting with an analyte to produce a measurable change in potential which can be correlated to the concentration of the analyte in the fluid sample. The test device optionally contains a reference electrode made of an amorphous semiconductor material having a reference material on the reference electrode.

Abstract: Nitric oxide-specific electrodes are useful for in situ detection of nitric oxide in biomedical applications and have at least a surface region thereof which is capable of forming complexes with nitric oxide, for example, nitrosyl complexes. The nitric oxide complexes formed at the surface of the electrodes apparently increase the concentration of nitric oxide available for detection, thereby leading to significantly improved relative responses as compared to other known nitric oxide electrode materials. Most preferably, the electrode has at least an exterior surface region which contains ruthenium and/or at least one oxide of ruthenium. The electrodes are advantageously conditioned in saline solution at +675 mV for about two hours.

Abstract: A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery. The probe comprises an integrated membrane-sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s).

Abstract: An electrochemical measuring cell for the simultaneous detection of different gas components in a gas sample, with a plurality of measuring electrodes (4, 5, 6) behind a diffusion barrier (7), with a common reference electrode (8) and counterelectrode (9) in an acid electrolyte, and with a potentiostatic evaluating circuit. Improvements in terms of service life for a sensor for the simultaneous detection of oxygen and carbon monoxide is provided with a reference electrode formed of a sintered mixture of metal and its metal oxide, preferably from the platinum group, the iridium group or gold and the potential of the CO-measuring electrode (5) relative to the reference electrode (8) is set at about 0 to 300 mV, and that of the O.sub.2 -measuring electrode (4) is set at a value between -300 and -800 mV.

Abstract: The invention provides an electrochemical reaction wherein a controlled amount of a first reagent is generated electrochemically at an electrode in electrical contact with a solution of an electrochemically inert salt, comprising applying a suitable electrical potential to the electrode for a suitable time to generate a controlled amount of the first reagent by electrochemical reaction between the electrode and a species in solution producing a localized thin layer environment comprising the first reagent in the vicinity of the electrode; and monitoring the amount or presence of the first reagent or a further species produced in solution in response to production of the first reagent. The method invention thus involves generating the first reagent in situ at an electrode.

Abstract: A device (10) is disclosed for measuring the concentration of metal ions in solution, particularly lead in blood. The device comprises a mercury free electrode (16), which is separated from the test solution (21) by a layer of material (20) which permits passage therethrough of the ions to be measured. In preferred embodiments an insulating layer (18) having an array of photoablated holes (19) is disposed between the electrode and the ion-permeable layer (20). Also disclosed are methods for operating the device and measuring ion concentration using anodic stripping voltametry, and assay kits incorporating devices as described together with appropriate meters and circuitry.

Abstract: A method for detecting and identifying a chemical substance in various phases such as a vapor phase and a liquid phase. The chemical substance being measured is diffused into a predetermined phase. Then, an electric state at an electrode existing in the predetermined phase is detected as a change with time based on the diffusion and absorption of the chemical substance on the electrode. A pattern of the change of the electric state with time is prepared. A fitting function based on the pattern is set and parameters of the chemical substance being measured are found. A distance between the parameters of the chemical substance being measured and parameters of the reference substance which is detected is determined.

Abstract: A method of measuring the concentration of ions in a solution, for example the concentration of solvated H.sup.+ ions i.e. the pH, comprises applying an a. c. signal across an ion-sensitive material immersed in the solution and measuring the complex impedance of the ion-sensitive material at a frequency at which the out-of-phase component of the impedance is sensitive to changes in pH. A probe for use in the method comprises two metal electrodes encased in pH sensitive glass, or two electrodes coated independently with ion-sensitive glass, then fritted together.

Abstract: When determining an activity of particular predetermined ions in a sample liquid by use of a device for measuring ionic activity including a pair of ion-selective electrodes which are selectively responsive to particular predetermined ions, a pair of spotting holes through which a sample liquid and a reference liquid are respectively supplied to the ion-selective electrodes and a porous bridge which communicates the spotting holes with each other so as to permit the sample liquid and the reference liquid spotted to the spotting holes to electrically contact with each other, for instance, the sample liquid is first spotted to one of the spotting holes of the device for measuring ionic activity with a first spotting tool, and at least one of the first spotting tool and the device for measuring ionic activity is thereafter moved to remove the first spotting tool away from the device for measuring ionic activity.

Abstract: A compact electrochemical cell utilized for the detection of numerous toxic gases. The cell includes working and counter electrodes, surrounded by a liquid electrolyte, all of which is enclosed behind a gas permeable, hydrophobic membrane. The working electrode may be a single electrode or may be composed of multiple glassy carbon electrodes arranged in a planar electrode array. The counter electrode is either spatially separated from the array or comprises one or more electrodes in the array. The electrolyte composition varies with the type of gas to be detected and can be aqueous, partially aqueous, or substantially non-aqueous. The electrolyte includes an alkali metal halide. A fixed potential applied between the working and counter electrodes is sufficient to initiate electrochemical reactions in the presence of the gas to be detected without interfering reactions of the electrolyte or air.

Abstract: The invention provides fittings for the ends of electrochromatography cols. Each fitting includes an annular electrode surrounding one end of the passage electrical fields to be applied. The fitting also contains a passageway for eluant flowing into or out of the column, an annular chamber for the electrode and a membrane separating the passageway from the annular electrode chamber. The membrane prevents gases and electrolytic products from entering the column eluent going through the chromatographic column. The membrane also isolate the electrodes from the compounds such as proteins and macromolecules being separated. A buffer solution was pumped through the electrode chamber to remove the gases and electrode products. The buffer flow through the electrode chamber maintains a constant pH and conductivity so that the electrical field applied by each electrode is constant. The buffer flow also serves to remove the heat generated in the electrode chamber.

Abstract: The invention is directed to a method for detecting error sources in an amperometric measuring cell 1 which includes at least a measuring electrode 2 and a counter electrode 3 within an electrolyte chamber 4 filled with an electrolyte solution 6. A permeable membrane 7 closes off the electrolyte chamber 4 with respect to the measuring sample. The method includes the steps of: providing a voltage source 10 outputting a voltage U to apply across the electrodes to generate a sensor current i(t) between the electrodes; starting with the voltage U across the electrodes at a reference voltage U.sub.0 with a reference current i.sub.0, increasing or decreasing the voltage U to a first voltage U.sub.1 during a first time span T.sub.1 ; shortly after the voltage U assumes the first voltage U.sub.1, measuring a first sensor current i.sub.1 and/or, toward the end of the first time span T.sub.1, measuring a second sensor current i.sub.2 ; and, comparing the sensor currents i.sub.1 and/or i.sub.

Abstract: The invention relates to a method for operating an amperometric measuring cell which includes at least a measuring electrode 2 and a counter electrode 3 in an electrolyte chamber 4 filled with an electrolyte. The measuring cell is closed off by a permeable membrane 7 with respect to the measurement sample to be detected. The method of the invention improves the run-in performance of the measuring cell 1. The method includes the step of applying a voltage U.sub.1 across the electrodes (2, 3) during a first time span T.sub.1 starting at a reference time T.sub.0. A reference voltage U.sub.0 is assumed at the start of the measurement and the voltage U.sub.1 is increased relative to the reference voltage U.sub.0.

Abstract: An electrochemical gas sensor assembly comprises an electrochemical gas sensor for sensing a selected gas. A filter is provided through which gas to be sensed must pass before reaching the sensor, the filter being adapted to prevent at least one non-selected gas from reaching the sensor but permitting passage of the selected gas. A temperature control system controls the temperature of the filter.

Abstract: This invention relates to a novel geo-electro-chemical sampling electrode and process. More specifically, this invention pertains to a novel ion collection electrode, and process, which can be used in the remote sampling of ions contained in ground water. This invention consists of a geo-electrochemical sampling apparatus comprising a hollow electrically non-conductive casing; an opening in the casing for enabling ions to be transported from the exterior of the casing to the interior of the casing, a cathode positioned in the interior of the casing, and electrically connected to the exterior of the casing; and, ion exchange resin contained in the interior of the casing between the cathode and the opening.

Abstract: Sensor devices for detecting components in fluid samples, especially by electrolytic analytical methods, comprising a detecting means (usually an anode, especially one of platinum) surrounded by a selectively permeable membrane barrier composed of a mixture of polyvinyl chloride and polyaryl sulphone polymers. Preferred proportions of the polymers are 1 to 9 parts of polyaryl sulphone for each part of polyvinyl chloride, and the mixture may be formed into membranes by solution casting. Preferably this barrier is used with an inner membrane, especially of porous polycarbonate. In use, these polymer mixtures are especially useful in their selective permeability to glucose. Also provided are methods for their use in analysis, and the polyvinyl chloride/polyaryl sulphone polymer compositions themselves and membranes made from them.

Abstract: Sensor devices comprising enzyme electrodes incorporating a microporous membrane coated with the carbonaceous material known as "diamond-like carbon" (most conveniently deposited by decomposition of a hydrocarbon, induced by radiation or a high electric field). The membrane material is preferably a polycarbonate and its thickness preferably less than 10 microns, and the coating is preferably 0.01 to 5 .mu.m thick. The preferred porosity is provided by pores of the order of 0.05 to 0.01 microns. The coated membrane imparts high resistance to fouling by contact with whole blood, extends the linearity of the electrode response over a substantially greater range, e.g. in the analytical determination of glucose in blood, and combines a high degree of restriction to passage of interferents while retaining high permeability to hydrogen peroxide and oxygen. Most conveniently used for amperometric measurements, especially using a Clark electrode pair, with an "active" anode of platinum.

Abstract: A gas sensor including an electrochemical sensor cell which has a anion-eange solid polymer electrolyte membrane with three attached electrodes is provided. The sensor cell contains no liquid electrolyte and is operated in the potentiostatic as well as the potentiodynamic modes to detect alkaline reactive gases, including vapors, such as hydrazines and derivatives thereof and ammonia. These sensor cells together with electronic circuitry, a pump and a power supply, fit into a compact, pocket-sized container to define the gas sensor of the invention which can detect traces of the above gases including 10 ppb of hydrazine and its derivatives and 10 ppm of ammonia. The invention includes the above gas sensor and the methods of operating same.

Abstract: A sensitive and rapid electrochemical sensor monitors motor oil deterioration, particularly antioxidation property, by determining the antioxidant and antiwear agent level remaining in an oil formulation. The electrochemical sensor is a two- or three-electrode electrochemical cell having a conductive electrolyte liquid or gel-like interphase over the electrode surfaces. The degree of deterioration of a motor oil in service is monitored by measurements of antioxidation or antiwear capacity of the oil. The electrochemical sensor can be used for monitoring other lubricants and hydrocarbons which contain electroactive additives. The electrochemical sensor allows measurements to be performed in-situ, without any chemical or physical pretreatment of the oil.

Abstract: A planar, solid-state electrochemical oxygen sensor having a substrate, conductive strips deposited on the substrate, and a dielectric layer insulating portions of the conductive strips except those portions which define a working electrode and at least one second electrode. The working electrode may be defined by an open printed region of the dielectric, or by a needle-punched or laser-burned hole or opening in the dielectric which exposes a small region of one of the conductive strips. A solid electrolyte contacting the electrodes is covered by a semipermeable membrane which may comprise an acrylonitrile butadiene copolymer or an acrylate-based copolymer. A sample chamber is defined by the membrane, a cover member, and a gasket therebetween, and has a volume of from about 1 to about 2 .mu.l. The gasket is formulated from the highly cross-linked polymerization product of epichlorohydrin. All sensor components are selected such that a sensor operable for at least 2 days under normal conditions is produced.