Abstract: An electrochemical cell includes a working electrode in contact with an aqueous electrolyte solution, a counter electrode in contact with the aqueous electrolyte solution, and a reference electrode in contact with the aqueous electrolyte solution. The working electrode comprises a plasma modified epitaxial synthesized graphene surface fabricated on SiC.

Abstract: An electrochemical H2S sensor comprises a housing, an electrolyte disposed within the housing, and a plurality of electrodes in contact with the electrolyte within the housing. The plurality of electrodes comprises a working electrode and a counter electrode. A surface area of the working electrode in contact with the electrolyte is less than a surface area of the counter electrode in contact with the electrolyte.

Abstract: A gas sensor for detecting one or more contaminants in a refrigerant includes a housing having disposed therein a membrane electrode assembly comprising a sensing electrode, a counter electrode, and a solid polymer electrolyte disposed between the sensing electrode and the counter electrode. The sensing electrode comprises nanoparticles of a first catalyst comprising noble metal. The counter electrode comprises nanoparticles of a second catalyst comprising noble metal. The sensing electrode in the sensor has been preconditioned by exposure under a positive voltage bias to a preconditioning gas comprising the contaminant(s) or their precursors or derivatives.

Abstract: A hydrogen sulfide (H2S) detecting apparatus for measuring the concentrations of hydrogen sulfide species in a given sample is disclosed. The hydrogen sulfide detecting apparatus can comprise a plurality of reaction chambers separated from a plurality of trapping chambers by a (H2S) permeable membrane, with the reaction chambers and trapping chambers each having buffer component(s) and/or reactive agents that expose the incoming sample to a particular pH and chemical environment in order to allow for the selective liberation and trapping of hydrogen sulfide from the sample.

Abstract: The present disclosure relates to methods and devices for gas sensing. A gas sensor includes a sensing element comprising at least an ionic liquid. The gas sensor also includes a set of electrodes for polarizing the sensing element and an electric power source for powering the set of electrodes, thus generating an impedimetric response signal from the sensing element. The gas sensor additionally includes readout circuitry for separately analyzing resistive and capacitive components in the impedimetric response signal. A method includes exposing a gas sensor to a gas. The gas sensor includes a sensing element including at least an ionic liquid. The method also includes polarizing the sensing element with an electrical signal at a first frequency, measuring an impedimetric response signal of the sensing element, separating the signal into resistive and capacitive components, and determining the composition of the gas based at least on the resistive and capacitive components.

Abstract: An electrochemical sensor measuring concentration of an analyte in a test fluid at 50° C. or above by voltammetry uses electrodes in contact with an electrolyte containing the analyte and a redox-active species electrochemically convertible between reduced and oxidised forms. At least one form of the redox active species is present within surfactant micelles. The surfactant micelles enhance thermal stability of the redox active species and may also solubilise a species with poor water solubility, such as t-butylferrocene. A downhole tool incorporating such a sensor comprises a barrier, permeable to the analyte, to separate the electrolyte from subterranean reservoir fluid, so that the sensor directly measures analyte which has passed through the barrier and thereby indirectly measures analyte in the test fluid.

Abstract: The disclosed invention relates to an amperometric gas sensor for measuring the concentration of an analyte, comprising: a solid support; and a working electrode in contact with the solid support; wherein the analyte comprises a dopant which when in contact with the solid support increases the electrical conductivity of the solid support. A sterilization process employing the amperometric gas sensor is disclosed.

Abstract: An electrochemical sensor incorporates a ferrocenophane which is a compound with at least one bridging group covalently attached to and connecting the two cyclopentadiene rings associated with the same iron atom. This bridging group maybe tetramethylene. As compared to an equivalent sensor with ferrocene, the tolerance of elevated temperature is improved and so is the working life at ambient temperature.

Abstract: A chronoamperometric method and device to determine concentration of an electrochemically active species in a fluid and pH of the fluid. A plurality of sets of calibration relationships may be determined for a sensor in an aqueous solution, the sensor having one or more working electrodes and one or more reference electrodes. A first plurality of potentials may be applied across the working and reference electrodes of the sensor in solution, and a first plurality of currents and current differences obtained as a function of the applied first plurality of potentials. Concentration of an electrochemically active species may then be determined as a function of the obtained first plurality of currents and current differences using the plural sets of calibration relationships, and pH of the solution may be determined as a function of the obtained first plurality of currents and current differences using the plural sets of calibration relationships.

Abstract: A gas sensor includes a housing having disposed therein a membrane electrode assembly comprising a sensing electrode, a counter electrode, and a polymer membrane disposed between the sensing electrode and the counter electrode. The polymer membrane comprises an ionic liquid retained therein. The sensor also includes a catalyst support that can be stable in a range of potentials to allow for detection mode and catalyst regeneration mode to be operative. The sensor further includes a circuitry and algorithm to implement the catalyst regeneration mechanism electrochemically. The sensor further includes a chamber for reference gas to which the counter electrode is exposed, and a chamber for test gas to which a gas to be tested is exposed. The sensor also includes a pathway for test gas to enter the chamber and a measured electrical circuit connecting the sensing electrode and the counter electrode.

Abstract: A carbon nanotube-based micron scale chemical sensor or sensor array is provided that enables the remote detection of hydrogen sulfide and other chemicals in a gas stream. The sensor is suitable for use in harsh environments of high temperature and pressure such as those encountered during petrochemical exploration and recovery. Multiplex sensor devices detect two or more chemical agents simultaneously, or they can detect conditions such as pressure, salinity, humidity, pH, or scale-forming ions. Incorporation of read out electronics and an RF signal generator into the sensor device enables it to communicate to a relay station or receiver for 3D mapping or other analysis. Methods are also provided for fabricating the chemical sensor device and using the device for detection.

Abstract: Technologies are generally described for gas filtration and detection devices. Example devices may include a graphene membrane and a sensing device. The graphene membrane may be perforated with a plurality of discrete pores having a size-selective to enable one or more molecules to pass through the pores. A sensing device may be attached to a supporting permeable substrate and coupled with the graphene membrane. A fluid mixture including two or more molecules may be exposed to the graphene membrane. Molecules having a smaller diameter than the discrete pores may be directed through the graphene pores, and may be detected by the sensing device. Molecules having a larger size than the discrete pores may be prevented from crossing the graphene membrane. The sensing device may be configured to identify a presence of a selected molecule within the mixture without interference from contaminating factors.

Abstract: A sulfur concentration detection system for detecting a sulfur concentration in a liquid includes a sensor having a conductive metal substrate and zinc oxide microstructures deposited on and protruding from the conductive metal substrate, a current source, and a voltage detector. An electrical resistivity of the zinc oxide microstructures is configured to change as a function of an amount of sulfur in the liquid available to react with zinc in the zinc oxide microstructures. The current source and the voltage detector are connected to the conductive metal substrate and configured to detect a change in the electrical resistivity of the zinc oxide microstructures.

Abstract: A sensor is disclosed for determining a sulfur concentration in a liquid, such as a liquid fuel. The sensor includes a substrate that is at least partially coated with zinc oxide and, more specifically, zinc oxide microstructures. The zinc oxide microstructures have a crystal lattice structure that is oriented in the (002) plane, are oxygen-deficient and have a rod-like microstructure. If the substrate is conductive, it may be connected directly to a working electrode which is connected to a potentiometer which, in turn, is connected to a reference electrode. If the substrate is non-conductive, the conductive layer can be deposited on the substrate prior to deposition of the zinc oxide to form a working electrode. An application of a constant current (or voltage) to either electrode will result in a voltage across (or current flow between) the working and reference electrodes.

Abstract: A measurement system is disclosed for determining a sulfur concentration in a liquid, such as a liquid fuel. The measurement system includes a first electrode that is at least partially coated with zinc oxide and, more specifically, zinc oxide microstructures. The zinc oxide microstructures have a crystal lattice structure that is oriented in the (002) plane. The first electrode may be connected to an electrometer which, in turn, may be connected to a second electrode. The second electrode may be disposed on a common substrate with the first electrode or may be in the form of a plate disposed substantially parallel to the first electrode.

Abstract: The disclosed invention relates to an amperometric gas sensor for measuring the concentration of an analyte, comprising: a solid support; and a working electrode in contact with the solid support; wherein the analyte comprises a dopant which when in contact with the solid support increases the electrical conductivity of the solid support. A sterilization process employing the amperometric gas sensor is disclosed.

Abstract: A gas sensor includes a housing having disposed therein a membrane electrode assembly comprising a sensing electrode, a counter electrode, and a polymer membrane disposed between the sensing electrode and the counter electrode. The polymer membrane comprises an ionic liquid retained therein. The sensor also includes a catalyst support that can be stable in a range of potentials to allow for detection mode and catalyst regeneration mode to be operative. The sensor further includes a circuitry and algorithm to implement the catalyst regeneration mechanism electrochemically. The sensor further includes a chamber for reference gas to which the counter electrode is exposed, and a chamber for test gas to which a gas to be tested is exposed. The sensor also includes a pathway for test gas to enter the chamber and a measured electrical circuit connecting the sensing electrode and the counter electrode.

Abstract: An electrochemical sensor measuring concentration of an analyte in a test fluid at 50° C. or above by voltammetry uses electrodes in contact with an electrolyte containing the analyte and a redox-active species electrochemically convertible between reduced and oxidised forms. At least one form of the redox active species is present within surfactant micelles. The surfactant micelles enhance thermal stability of the redox active species and may also solubilise a species with poor water solubility, such as t-butylferrocene. A downhole tool incorporating such a sensor comprises a barrier, permeable to the analyte, to separate the electrolyte from subterranean reservoir fluid, so that the sensor directly measures analyte which has passed through the barrier and thereby indirectly measures analyte in the test fluid.

Abstract: An electrochemical sensor is provided especially for gases. The electrochemical sensor has a mediator compound, which is both dissolved in an electrolyte (9) in a saturated form and is present as an excess solid (10) in the electrolyte (9).

Abstract: A wellbore tool has an electrochemical sensor for measuring the amount of hydrogen sulphide or thiols in a fluid downhole in a wellbore. The sensor comprises a temperature- and pressure-resistant housing containing a flow path for the fluids. The fluids flow over one side of a gas permeable membrane the other side of the membrane being exposed to a chamber containing at least two electrodes and containing a reaction solution which together with the hydrogen sulphide or thiols create a redox reaction resulting in an electrical current dependent upon the amount of hydrogen sulphide or thiols in the fluid. Measurement is made by passing formation fluid along the flow path and repeatedly applying varying potential to one electrode and measuring the peak current flowing between that electrode and a second electrode.

Abstract: Refinery feedstocks can be characterized based on any of: dissociation of acids in the crude, breakup of naphthenic acid molecular associations, and/or dissociation of sulfur compounds in the feedstocks. The characterization is performed as a function of temperature via any of electrical resistivity measurement, vibrational spectroscopic analysis, voltammetry, electrochemical impedance spectroscopy (EIS) and combinations thereof The method can be practiced in any of refinery, terminal, and laboratories. It can be used in conjunction with models and hardware to optimize the usage of refinery feedstocks in the blending and valuation of the feedstocks. In one embodiment, the characterization of refinery feedstocks is via the use of EIS.

Abstract: A mediator-based electrochemical gas sensor reacts selectively with hydrogen sulfide. The gas sensor has an electrolyte solution (9), which contains a mediator compound in the form of metallates of transition metals.

Abstract: An electrochemical sensor for measurement of hydrogen sulfide is described. The electrochemical sensor comprises an electrolyte; an electrolyte container comprising a hydrogen sulfide permeable membrane; a working electrode and a reference electrode both disposed in the electrolyte; and an instrument capable of maintaining a fixed DC potential in the range of 0 mV to 1,000 mV between the working electrode and the reference electrode. Also a method of detecting hydrogen sulfide in a sample. The method comprises providing an electrochemical sensor; at least partially immersing the gas permeable membrane in the sample; and detecting hydrogen sulfide in the sample. The detection may be qualitative or quantitative.

Abstract: The application generally describes devices, systems, and methods for determination of one or more analytes. Embodiments described herein may be useful as sensors for analytes such as explosives, chemical warfare agents, and/or toxins. In some cases, chemiresistor or chemFET sensor devices for monitoring volatile organics, especially chemical warfare agents such as sarin, are described. Some embodiments comprise functionalised carbon nanotube/conjugated polymer composites (6) as sensing material. In some embodiments, the polymer is poly(3-hexylthiophene), 3PHT, optionally substituted with calixarenes, or hexafluoroisopropanol susbstituted polythiophene, HFIP-PT. Biosensing embodiments are also described, as well as methods of manufacturing the devices.

Abstract: An electrochemical gas sensor, a method for making the sensor and methods for the detection of a gaseous species. The electrochemical gas sensor is a solid-state gas sensor that includes a solid polymer electrolyte. A working electrode is separated from a counter electrode by the solid polymer electrolyte. The sensor can include a multilaminate structure for improved detection properties, where electrode microbands are disposed within the solid polymer electrolyte.

Abstract: Exposure of diffusion limited sensors to target gas concentrations above their range can result in non-linearity and slow recovery times. Applications where both a high concentration and a low concentration need to be measured in succession are problematic if the high concentration gas adversely affects the response of the sensor to low gas concentrations. By employing two sensors, one for high range and one for low range gas concentrations, and a means to isolate the low range sensor from the gas source whenever the concentration exceeds a threshold value as determined by the high range sensor and reengage the low range sensor when the target gas concentration falls below the threshold, allows both the measurement of target gas to high concentrations as well as the high resolution measurement of target gas at low concentrations.

Abstract: A wellbore tool has an electrochemical sensor for measuring the amount of hydrogen sulphide or thiols in a fluid downhole in a wellbore. The sensor comprises a temperature- and pressure-resistant housing containing a flow path for the fluids. The fluids flow over one side of a gas permeable membrane the other side of the membrane being exposed to a chamber containing at least two electrodes and containing a reaction solution which together with the hydrogen sulphide or thiols create a redox reaction resulting in an electrical current dependent upon the amount of hydrogen sulphide or thiols in the fluid. Measurement is made by passing formation fluid along the flow path and repeatedly applying varying potential to one electrode and measuring the peak current flowing between that electrode and a second electrode.

Abstract: An electrochemical sensor for measuring the amount of hydrogen sulphide or thiols in a fluid in a wellbore comprises a temperature- and pressure-resistant housing containing a flow path for the fluids. The fluids flow over one side of a gas permeable membrane made of zeolite or a suitable ceramic material, the other side of the membrane being exposed to a chamber containing a reaction solution which together with the hydrogen sulphide or thiols create a redox reaction resulting in an electrical current dependent upon the amount of hydrogen sulphide or thiols in the fluid.

Abstract: An electrochemical sensor and method of detecting gaseous analytes are provided, which involve the use of a working electrode comprising edge plane pyrolytic graphite.

Abstract: An electrochemical gas sensor is provided with a carbon-based measuring electrode (3) that it can be used for a large number of electrochemical detection reactions and can be manufactured at a low cost. The measuring electrode (3) contains carbon nanotubes.

Abstract: A gas sensing device (nanosensor) includes a substrate with at least a pair of conductive electrodes spaced apart by a gap, and an electrochemically functionalized semiconductive nanomaterial bridging the gap between the electrodes to form a nanostructure network. The nanomaterial may be single-walled carbon nanotubes (SWNTs) functionalized by the deposition of nanoparticles selected from the group consisting of an elemental metal (e.g., gold or palladium), a doped polymer (e.g., camphor-sulfonic acid doped polyaniline), and a metal oxide (e.g. tin oxide). Depending on the nanoparticles employed in the functionalization, the nanosensor may be used to detect a selected gas, such as hydrogen, mercury vapor, hydrogen sulfide, nitrogen dioxide, methane, water vapor, and/or ammonia, in a gaseous environment.

Abstract: A device is provided for measuring the gas content in a molten metal, the device including an immersion end having a gas-collecting body, a gas supply line opening on the immersion end, and a gas discharge line for the gases passing through the gas-collecting body. The gas-collecting body contains materials, which in contact with the molten metal do not form liquid reaction products.

Abstract: In one embodiment, the present invention is directed to a pulsed electrochemical detection method comprising (a) flowing a liquid sample stream including at least one analyte past a working electrode in a flow-through cell; (b) applying at least three pulsed electrical potentials to the working electrode, (1) a first conditioning potential, (2) a second detection and oxidative cleaning potential, and (3) a third reductive cleaning potential, said second potential being higher than said first and third potentials and said first potential being higher than said third potential; and (c) detecting the output from said working electrode during the time period of applying said second potential.

Abstract: An electrochemical sensor for measurement of hydrogen sulfide is described. The electrochemical sensor comprises an electrolyte; an electrolyte container comprising a hydrogen sulfide permeable membrane; a working electrode and a reference electrode both disposed in the electrolyte; and an instrument capable of maintaining a fixed DC potential in the range of 0 mV to 1,000 mV between the working electrode and the reference electrode. Also a method of detecting hydrogen sulfide in a sample. The method comprises providing an electrochemical sensor; at least partially immersing the gas permeable membrane in the sample; and detecting hydrogen sulfide in the sample. The detection may be qualitative or quantitative.

Abstract: A method of adjusting the output of an electrochemical sensor includes the steps of: simulating the presence of an analyte gas electronically; measuring a response of the sensor to the electronic simulation; and adjusting the output of the sensor as a function of the measured response to the electronic simulation. The method of adjusting the output of an electrochemical sensor having a working electrode and a counter electrode preferably includes the steps of: electronically causing a current flow between the working electrode and the counter electrode; measuring a response of the sensor to the current demand; and using the measured response to adjust the sensor output during sampling of an analyte gas.

Abstract: The 3-mercaptopropylsulfonic acid (MPSA) breakdown product of the bis(sodiumsulfopropyl)disulfide (SPS) additive used in acid copper plating baths accelerates copper electrodeposition and can be detected by cyclic voltammetric stripping (CVS) analysis. In the presence of oxygen, MPSA decomposes rapidly in acid copper sulfate baths so that the CVS stripping peak area (Ar) decreases on successive cycles. The slope of a plot of Ar vs. CVS cycle number (or time) or logarithm of the CVS cycle number (or time) provides a measure of the initial MPSA concentration.

Abstract: An electrochemical gas sensor is provided with a carbon-based measuring electrode (3) that it can be used for a large number of electrochemical detection reactions and can be manufactured at a low cost. The measuring electrode (3) contains carbon nanotubes.

Abstract: An electrochemical sensor, especially for gases, is provided having a mediator compound based on transition metal salts of polybasic acids and/or transition metal salts of polyhydroxycarboxylic acids. The electrochemical sensor also contains a DLC, BDD or a precious metal thin-layer measuring electrode (3). The electrochemical sensor may be used for determining SO2 and H2S.

Abstract: An electrochemical cell for applications such as electrochemical fuel cells, or electrochemical cell gas sensors used for detection of target gas species in environments containing or susceptible to presence of same. The electrochemical cell utilizes an ionic liquid as an electrolyte medium, thereby achieving a broader range of operational temperatures and conditions, relative to electrochemical cells utilizing propylene carbonate or other conventional electrolytic media.

Abstract: Provided are methods of producing an electrode capable of binding an analyte thereto comprising: providing a substrate capable of binding a dithiol molecule thereto; electrochemically treating the substrate using cyclic voltammetry to provide a treated substrate having a fractal dimension of greater than about 2; and contacting the treated substrate with dithiol molecules to produce an electrode having dithiol groups attached thereto and capable of binding an analyte to be detected thereto. Also provided are methods of accumulating and detecting analytes using the electrodes produced via the methods of the present invention.

Abstract: A sensor for determining the concentration of sulphur compounds in a liquid includes: a working electrode in contact with the liquid to be analyzed; a referenced electrode insulated from the liquid to be analyzed; a liquid-impermeable membrane located between the working electrode and the reference electrode and permeable to an ion that may form a chemical compound with the sulphur compounds in the liquid to be analyzed; and a reference material in contact with the reference electrode or forms the reference electrode.

Abstract: The present invention relates to a method for determining concentration of brightener and leveler contained in an aqueous acid metal electroplating solution, by firstly determining the concentration of the brightener at a first set of measurement conditions, and secondly determining the concentration of the leveler at a second set of measurement conditions, provided that the first set of measurement conditions differ from the second set of measurement conditions on the rotation speed of a rotating disc electrode used for measuring plating potential of said aqueous acid metal electroplating solution, and optionally, the electroplating duration at which the plating potential of said aqueous acid metal electroplating solution is measured, provided that the first rotation speed is lower than the second rotation speed, and that the first electroplating duration is shorter than the second electroplating duration.

Abstract: The concentration of dithionite can be fast and accurately measured in a sample by a method wherein a predetermined amount of peroxide is added to said sample, following which catalase is added to said sample in an incrementally growing dose during a predetermined time, monitoring the production of oxygen in the sample, and recording the onset of oxygen production as well as the amount of oxygen produced as a function of time. The recorded values are then taken as a measure of the amount of dithionite present in the sample.

Abstract: The present invention relates to a device and method for measuring the level of an oxidant or antioxidant analyte in a fluid sample. The device comprises a disposable electrochemical cell, such as a thin layer electrochemical cell, containing a reagent capable of undergoing a redox reaction with the analyte. When the device or method is to be used with slow-reacting analytes, heat may be applied to the sample by a resistive heating element in the device or by an exothermic material contained within the electrochemical cell. Application of heat will accelerate the rate of the redox reaction between the reagent and the analyte and thus facilitate the electrochemical measurement of slow-reacting analytes.

Abstract: An apparatus for determining a component present in a liquid sample in free state or bound to constituents, preferably for measuring the SO2 content in the sample, has a locating space for the liquid sample, a sensor preferably responding selectively to the component, preferably based on an electrochemical cell, and a gas piping system via which a carrier gas can be passed from the locating space through the sensor (FIG. 1).

Abstract: A thick film electrochemical micro-sensor device for detecting or monitoring sulfur dioxide, comprising a substrate to which is applied a working electrode, a counter electrode, a reference electrode, and optionally a heater and a temperature detector, wherein a portion of the electrodes is covered with an insulator, and a portion of the electrodes is covered with an electrolyte. The device is especially useful for detecting or monitoring sulfur dioxide in emission gases. A method of detecting or monitoring sulfur dioxide emissions using the electrochemical micro-sensor device includes contacting the emission gas with the sensor of the present invention, measuring the current output of the sensor, determining if the current output indicates the presence of sulfur dioxide, and generating a signal, that can be used to actuate a scrubber system when a pre-determined level of sulfur dioxide is detected.

Abstract: Acid copper electroplating baths used to form ultra-fine circuitry features on semiconductor chips contain suppressor, anti-suppressor and leveler additives that must be closely controlled in order to obtain acceptable copper deposits. Cyclic voltammetric stripping (CVS) methods are available to measure the concentrations of the suppressor and anti-suppressor based on the effects of these additives on the copper electrodeposition rate. The present invention is a method that also uses measurements of the copper electrodeposition rate to determine the concentration of the leveler additive. The other two additives are included in the measurement solution at concentrations determined to provide the optimum compromise between minimal interference, high sensitivity and good reproducibility for the leveler analysis.

Abstract: A gas sensor for measuring an amount of a measurement gas component, including a solid electrolyte having an internal space, a gas-introducing port for introducing measurement gas from an external space into the internal space, diffusion rate-determining means between the internal space and the gas-introducing port, and inner and outer pumping electrodes for pumping-processing oxygen contained in the measurement gas. The diffusion rate-determining means includes slits each having, when viewed in a plane substantially perpendicular to a longitudinal extension axis thereof, two dimensions, with at least one dimension of each slit being not more than 10 microns.

Abstract: Disclosed are methods for analyzing additive breakdown products in electroplating baths as well as methods of controlling the presence of such breakdown products in electroplating baths.

Abstract: A low cost room temperature electrochemical gas sensor with humidity compensation for sensing CO, alcohol vapors and other toxic analyte gases has a solid protonic conductive membrane with a low bulk ionic resistance. A sensing electrode and a counter electrode, optionally a counter electrode and a reference electrode, which are separated by the membrane, can be made of mixed protonic-electronic conductors, or can be made of a thin electrically conducting film such as platinum. A reservoir of water maintain the solid protonic conductive membrane at constant 100 percent relative humidity to compensate for ambient humidity changes. Embodiments of the inventive sensor also include an electrochemical analyte gas pump to transport the analyte gas away from the counter electrode side of the sensor.