Abstract: A solid electrolyte gas sensor comprising: a base plate of a solid electrolyte, on which are disposed a detecting electrode for detecting a selected gas, a reference electrode, and a conductor portion for external connection such as an outer lead.A process of producing a joined body of a ceramic member and a hard-to-sinter oxyacid salt crystal, the process comprising the steps of: impregnating a melt of a hard-to-sinter oxyacid salt such as a sulphate or a carbonate into a porous ceramic plate having micropores extending through the entire thickness thereof; then cooling the impregnated ceramic plate to form a composite plate composed of the ceramic plate with the micropores filled with a crystal of the hard-to-sinter oxyacid salt; and joining the composite plate to a ceramic base.

Abstract: An device for monitoring workplace air comprises a monitor cell comprising a base and a removable assembly. The removable assembly comprises (1) a flat, electrically insulating substrate having a first surface, (2) an electrolyte cell having an anode and a cathode disposed on the first surface, the anode and cathode spaced apart to define a controlled volume for holding a quantity of an electrolyte, and (3) means for applying a controlled electrical potential to the cathode. The base comprises (1) an air inlet portion for sampling air, (2) an air outlet portion connected to an air sampling pump, (3) a channel connecting the air inlet and the air outlet and adapted to introduce air to the electrolyte in the electrolyte cell, (4) a reservoir for storing the electrolyte for the electrolyte cell, and (5) a wick for supplying electrolyte from the reservoir to the electrolyte cell.

Abstract: A method and apparatus are disclosed for measuring a resistance of a sensor. The apparatus injects a first test current into the sensor and then measures a substantially stable first voltage level across the sensor when the first test current is present. The apparatus then injects a second test current into the sensor, the second test current being substantially equal to but opposite in polarity to the first test current. A substantially stable second voltage level across the sensor is measured when the second test signal is present. Using the first measured voltage level and the second measured voltage level, the apparatus calculates the resistance of the sensor.

Abstract: The present invention provides a new device for use in measuring lead levels in biological and environmental samples. Using square wave coulometry and colloidal gold particles impregnated on carbon electrodes, the present invention provides a rapid, reliable, portable and inexpensive means of detecting low lead levels. The colloidal gold modified electrodes have microelectrode array characteristics and produce significantly higher stripping detection signals for lead than are produced at bulk gold electrode surfaces. The method is effective in determining levels of lead down to at least 5 .mu.g/dL in blood samples as small as 10 .mu.L.

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

Abstract: A simple potentiostat circuit for use in biasing a three-electrode electrochemical cell is described wherein a direct electrical connection is made between the sensing electrode and the reference electrode during normal operation of the cell. Preferably the electrical connection is a resistor. By selecting the resistive value properly, the zero gas current of the cell is eliminated without negatively affecting the response of the cell.

Abstract: A dialysis electrode device comprises a shank of needle-like proportions and formed from a hollow dialysis fiber membrane. The shank is closed at its distal end by a sealing plug and, at its proximal end, it is sealed to and in communication with an auxiliary chamber defined by a tubular body part. Electrolyte is supplied to the chamber in the shank through an inlet conduit and is removed via an outlet conduit connected to the auxiliary chamber. The device also includes a dialysis or first working electrode, which is insulated save for a length thereof disposed within the hollow shank, a counter electrode and a reference electrode mounted within the auxiliary chamber. It may be used in clinical medicine and the food, pharmaceutical and other industries where it is desirable to analyze or monitor the presence of chemical substances.

Abstract: A sensing element, for use in determining the presence and/or concentration of a species in a solution, comprises a flat insulating substrate (10) having at least one thin metallic electrode (16) deposited on it and overlaid with an insulating layer (20). The electrode (16) and insulating layer (20) bridge a weakening groove (12) formed in the substrate. Immediately before use, the element is broken along the groove to expose a cross-sectional surface (24) of the element, and thus a cross-sectional working surface (26) of the electrode. The thickness (T) of the element is comparable to or less than the concentration boundary layer thickness of the solution. This exposed working surface is the only part of the electrode in contact with the solution. In use, the element can be vibrated so as to improve its sensitivity.

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

Abstract: This invention relates to a microelectrode comprising graphite, oil and, additionally, a compound selected from the group of lipids, glycolipids, lipoproteins, fatty acids, fatty acid derivatives, any water insoluble species and perfluorosulfonated compounds and salts thereof. This invention also relates to a method for using the microelectrode, a device that may be employed with the microelectrode, a method for making the microelectrode, and a method for using the device with the microelectrode.

Abstract: A solid electrolyte sensor device for determining gas concentrations in measurement gases, with a sensor formed by a solid electrolyte which is arranged between at least two electrodes. The electrodes are permeable to gas and at least one of the electrodes faces the measurement gas. An electrical device is also provided for detecting and processing concentration-dependent sensor output values. For the purpose of permanently preventing disruptive adsorption of measurement gas components on the sensor or on the corresponding sensor electrode, an adjustable oxygen source is arranged in the vicinity of the sensor electrode which faces the measurement gas so that oxygen or oxygen radicals can be introduced into the measurement gas via this oxygen source for the oxidation of the measurement gas.

Abstract: A feedback control system for providing automated control of multi-component chemical concentrations in a hydrogen peroxide/ammonia (SC-1) aqueous bath or in a hydrogen peroxide/hydrochloric (SC-2) aqueous bath used for semiconductor processing. A sample from the liquid bath is routed to two sensors. Three separate schemes for determining concentrations of the two chemicals in the bath are provided by the selection of one of three separate pairs of sensors. A processor is used to monitor and control the chemical makeup of the bath.

Abstract: Apparatus and methods for quickly and easily detecting trace amounts of metallic or non-metallic, electro-active substances, and in particular trace amounts of metals, such as lead in a portable, hand-held detector system with single potential control.

Abstract: A method for determining concentrations of solutes such as alcohols, amino acids, carbohydrates, calcium, etc. in water solution. The open-circuit potential shift of an oxidatively pretreated nickel electrode in alkaline solution is used.

Abstract: A small oxygen electrode and a method of bonding a fluorine resin film are disclosed. This small oxygen electrode includes a flat electrode substrate having at least two electrodes (a working electrode and a counter electrode) formed thereon, and a container substrate having dents formed to confront the two electrodes and contain an electrolyte therein. The container substrate is bonded to the flat electrode substrate, so that the dent confronting the electrode constituting the working electrode has a through hole extending to the side opposite to the flat electrode substrate and a gas-permeable film is formed to cover the through hole. By using this dent structure, the preparation of an oxygen electrode can be conducted while maintaining a wafer form throughout the process, and formation of an electrode pattern can be facilitated.

Abstract: An electrocatalytic device for sensing gases. The gas sensing device includes a substrate layer, a reference electrode disposed on the substrate layer comprised of a nonstoichiometric chemical compound enabling oxygen diffusion therethrough, a lower reference electrode coupled to the reference electrode, a solid electrolyte coupled to the lower reference electrode and an upper catalytically active electrode coupled to the solid electrolyte.

Abstract: A method for producing electrochemical impedance spectra. Spontaneously occuring coupling current noise between an array of electrodes which may be of substantially the same material is detected. A time domain record of the detected current noise is stored and the time domain record of the detected current noise is transformed to the frequency domain. Spontaneously occurring potential noise between the array of electrodes and a further electrode is detected. A time domain record of the detected potential noise is stored and the time domain record of the detected potential noise is transformed to the frequency domain. The frequency domain current noise and potential noise transformations are then transformed to the impedance domain to produce the required electrochemical impedance spectra.

Abstract: An instrument for measuring the throwing power, electrochemical efficiency and operating current density of an electrolyte comprises a number of removable electrodes (20) arranged inside a nonconductive probe body (10) with an open end (11) and an optional solution circulation opening at its opposite end (30) with the electrodes connected via current meters (80) to a current controller (70).

Abstract: A sequential electrochemical reduction method and apparatus are provided for assessing and restoring solderability of electronic component leads. The method detects and quantifies the presence of metallic oxides that are detrimental to solderability by sequential electrochemical reduction in contact with an electrolyte in an inert atmosphere. A cathode having a high hydrogen overvoltage is placed in contact with the electrolyte. A solderable portion of the component to be tested is placed in contact with the cathode and the electrolyte. An inert counter electrode and a reference electrode are also placed in contact with the electrolyte. A current is passed between the cathode and inert electrode, and the voltage and current are measured as a function of time during reduction of metallic oxides on the solderable portions of the component.

Abstract: A level of a chemical in a fluid is accurately measured by an analyzer having an electrode assembly separated from the fluid by a membrane. The electrode assembly is energized to provide a steady state signal and a pulsed signal, both of which indicate the level of chemical in the fluid, but with only the pulsed signal being substantially unaffected by fouling of the membrane. The pulsed signal and the steady state signal are used to determine a predicted value that the steady state signal will have in the absence of fouling. The predicted value is then used to correct the steady state current to compensate for fouling of the membrane.

Abstract: A MIS diode sensor having a Pd/Cu alloy electrode is sensitive to and can detect CO, H.sub.2, C.sub.2 H.sub.2 and C.sub.2 H.sub.4. An array of MIS diode sensors having varying electrode compositions can indicate a fault in an electrical transformer by the detection of at least one of the key fault gases CO, H.sub.2, C.sub.2 H.sub.2 and C.sub.2 H.sub.4.

Abstract: A galvanic cell type gas sensor which utilizes the respective merits of galvanic cell type and polaro type gas sensors so that a plurality of gasses can be detected by one sensor. One working electrode is utilized in conjunction with two or more counter electrodes which are different in kind from each other. Each of the electrodes are individually selected corresponding to a type of gas to be detected. Also, drift in the measurement of one of the detected gasses can be corrected based upon the measurement of another of the detected gasses.

Abstract: A potentiometric biosensor, test strip, reagent and a potentiometric method for detection or measurement of an analyte from a fluid sample. The biosensor includes indicating and reference electrodes, and a reagent, which overlays a portion of the surface of the indicating electrode. The reagent generally includes an enzyme and a redox mediator. When a fluid sample (e.g., blood) containing an analyte (e.g., glucose) is added to the reagent, the enzyme (e.g., glucose oxidase) catalyzes a reaction involving enzyme, redox mediator (e.g., potassium ferricyanide), and analyte.This reaction may be monitored by monitoring the electrical potential at the indicating electrode surface. (Electrical potential at the indicating electrode surface changes as the concentration of oxidized and reduced forms of the redox mediator change at the indicating electrode surface.

Abstract: A method of improving the utility of electrochemical glucose sensors by decreasing either or both their settling time and their sensitivity to interfering compounds. In particular, the settling time of an electrochemical glucose sensor is improved by pretreating the operating electrode with a negative electric current at a constant current density. The sensor's sensitivity to intefering compounds is reduced by operating the sensor at a reduced voltage while the glucose concentration measurement is being made.

Abstract: A thin film, solid state amperometric detector for nitric oxide is provided based upon a mobile cation electrolyte that selectively transmits nitrosonium cations (NO.sup.+) therethrough. The presently most preferred embodiment employs NO-.beta.-alumina as the mobile cation electrolyte. The electrodes of the detector are preferably arranged in a bipotentiostat arrangement. The first and second working electrodes share a common reference electrode and a common counter electrode, which are positioned such that the potentials of the first and second working electrodes can be independently controlled. The first working electrode is exposed to a fluid (liquid or gaseous), whereas the second working electrode is normally isolated from the fluid. The first working electrode is set at a potential capable of oxidizing NO to NO.sup.+, the NO.sup.+ moves through the mobile cation solid electrolyte to the second electrode, and the second working electrode is set at a potential capable of reducing the NO.sup.+ back to NO.

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

Abstract: A reference electrode for an electrochemical three-electrode sensor, including a shaft, a platinum electrode embedded in the shaft, a platinum oxide coat at least partially covering the platinum electrode, and a polyhydantoin coat completely covering the platinum oxide coat and any exposed surface of the electrode not coated with platinum oxide.

Abstract: A portable, ready-for-use analyte measuring device is provided for the measurement of multiple sequential fluid samples. The device has a disposable cartridge, a calibrating fluid external to the cartridge and an analyzer. The cartridge has a housing, inlet for introduction of fluids into the housing, flow cell in fluid connection with the inlet, a waste collection area or reservoir in fluid connection to receive fluids from the flow cell, and at least one flow control means in fluid connection with the reservoir. The flow cell has a flow-through channel with one or more hydrated sensors arranged along the channel that has fluid therein. Also the flow cell has one or more spaced-apart reference electrode containment spaces in conductive contact with a contained quantity of reference fluid for the number of multiple sequential tests for the cartridge. The reference electrode containment space is spaced apart from but in conductive relation with the one or more sensors.

Abstract: A system and method of detecting the end of useful life in a gas sensor cell having a cathode, anode, one of which is consumable, and an electrolyte, and a circuit for controlling the flow of gas to the cell and a sensing resistor and circuit connected to said cathode and said anode, the consumable electrode is provided in the form of a plurality of discrete elements which are sequentially connected in circuit with the other electrode, sensing resistor and circuit. A drop in current between respective ones of the consumable electrode is an indication of the approach of the end of the useful life of the gas sensor.

Abstract: An electrochemical sensor having at least two electrodes that communicate with a liquid measurement cell electrolyte and a housing that encloses the electrodes and the electrolyte. The surfaces of the electrodes facing the electrolyte bridge web connecting the electrodes are covered with a semipermeable membrane.

Abstract: The invention relates to a method for determining the concentration of gases in a mixture of gasses by means of a gas sensor composed of three electrodes 1,2,3 and a solid electrolyte 4 upon the surface of which are secured the electrodes. A voltage Us being composed of a dc component Udc and an ac component Uac is applied to at least two electrodes, the measuring electrode 1 and the counter electrode 2. Us is controlled with reference to the reference electrode 3. The voltage components Udc and Uac of the voltage Us are chosen so that the metal salt formed by the ions of the solid electrolyte 4 with the gaseous components to be detected is again decomposed. The ion, current flowing between the electrodes is measured in dependence upon the voltage as applied. The concentration of the several gasses can be determined by known mathematical methods from the functional relation between the ion current and the voltage Us.

Abstract: In a first embodiment, a target analyte in solution is detected by exposing the solution to an electrode that includes a conducting electroactive polymer to which a periodic alternating voltage is coupled. Upon exposure to the analyte, an electrode characteristic is varied, which variation is detected by measuring electrode current as a function of time and as a function of the periodic alternating voltage. The alternating voltage waveform has an oxidizing time period and a reduction time period, which periods and waveform duty cycle may be controlled to enhance electrode sensitivity, selectivity, and to substantially eliminate electrode fouling and data hysteresis. In a second embodiment, a receptor is bound to the electrode, to which is coupled an alternating voltage waveform that permits a mating target substance to reversibly bind to the receptor such that measurement of electrode current provides a measure of such reversible binding.

Abstract: An electrochemical sensor having a substrate, conductive strips deposited on the substrate, and a layer insulating portions of the conductive strips except those portions which define a working electrode and at least one second electrode. 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.

Abstract: Apparatus for assessing solderability of electronic component leads and printed wiring boards by sequential electrochemical reduction. The apparatus detects and quantifies the oxides present on copper, solder, andintermetallics that are detrimental to solderability. A solderable portion of the component to be tested is immersed in an electrolyte to form an electrode. An inert counter electrode and a reference electrode are also placed in the electrolyte. A current is passed from the inert counter electrode to the tested component, and the potential between the component and the reference electrode is recorded as a function of time. In a plot of the electrode potential versus the total charge passed, a series of inflection points identify and quantify particular metallic oxides present on the solder. The plot is compared with previous analyses of aged specimens having known oxide compositions that correlate with degradation of solderability.

Abstract: An electrochemical detector cell includes a first block having a planar first working surface, and a first working electrode embedded in the first block member. The first working electrode includes analyte contacting surface disposed co-planarly with the first working surface. A second block member has the second working surface placeable in an opposed, adjacent relation to the first working surface, and has an inlet port disposed an opposed, adjacent relation to the analyte contacting surface of the first working electrode. The second block also includes a coupling means for permitting an analyte delivery tube to be coupled to the second block member to position an end of the analyte delivery tube adjacent to the inlet port. A generally circular circumferential channel for collecting analyte is disposed radially outwardly of the first working electrode. An outlet is disposed at the channel for conducting analyte away from the channel.

Abstract: An oxygen sensor is based on a thin film of a compound oxide supported on a substrate such as quartz. The compound oxide has a general formula ABO.sub.2.5+x, where A is an element of the lanthanum family, alkaline earth metal or their mixture, and B is a transition metal or a mixture of transition metals. X is a variable number, changing from about 0 to about 0.5 between the reversible oxygen-deplete and oxygen-rich forms of the oxide. In an elevated temperature and oxygen-containing atmosphere, the thin film can undergo reversible bulk oxidation resulting in a detectable change of its physical properties such as mass, optical transmissivity and electrical resistance.

Abstract: Multiple frequency sources are used to apply a time varying signal to a scanning tunneling microscope and a current or voltage passing between the electrodes of the microscope is measured by a microwave spectrum/network analyzer which detects simultaneously at the multiple input frequencies and combinations thereof. This permits multiple substances to be monitored simultaneously. By choosing appropriate frequencies of input signals to be mixed or combined before application to the sample, it is possible to measure at a difference frequency which may improve signal to noise ratio and possible to match generating and reaction potentials and relaxation times to render detection possible. When applied to an array of Coulomb blockade devices used as a current standard, accuracy of the standard can be tested and the signal-to-noise ratio can be improved in the measurements, or the thresholds of the devices can be detected.

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

Abstract: An electrochemical gas sensor comprises sensing and counter electrodes (1,2). A conduit (15) permits access of gas to the sensing electrode (1). An electrolyte reservoir (23). A porous, block-like body (24) is positioned in the reservoir (23) for conveying electrolyte to the sensing and counter electrodes and at least partly supporting other components of the sensor.

Abstract: A method is described for definition of peracids in the presence of hydrogen-peroxide in a solution with the following steps:(1) introducing an electrode-design, which provides at least one measurement electrode and one counter electrode into the solution,(2) Loading of the electrodes with varying potentials; and(3) Measurement of the current by using a measurement electrode.With such a method the peracid solutions always contain hydrogen-peroxide, which also shows similar reactions.In order to determine the peracid concentration, a value of the determined current is compared with a corresponding value of an earlier recorded electrode-design.

Abstract: A polarographic electrochemical cell for the measurement of oxygen in ppb. The cathode in the system is a non-depleting carbon polytetrafluoroethylene electrode catalytically specific for oxygen reduction. The anode is a composite nickel matrix. The reaction at the anode is an electrochemical oxidation reaction but there are no soluble byproducts that contaminate the electrode. The reaction at the anode is a simple oxidation, state-of-change of the nickel in the nickel composite matrix.

Abstract: An amperometric sensor device comprises in combination a sensor (21) having a planar structure obtained by photolithographic techniques and a circuit (22) for measuring the intensity of the electrochemical current generated by the sensor (21). The planar structure has an insulating substrate (23 to 25) and a set of electrodes composed of a working electrode (29), a counter electrode (30) and a reference electrode (31). A diffusion membrane (32) is deposited on the working electrode (29). Connection means (26) are provided to connect the electrodes (29,30,31) to the measuring circuit (22). According to the invention, the active conducting part of the working electrode (29), situated at the surface of the substrate (23) is entirely covered by the diffusion membrane (32) which overlaps this electrode (29) over its entire peripheral zone, whereas this membrane is entirely exposed so that, during the operation of the device (20) it is in contact with the fluid to be analysed over its entire surface.

Abstract: Disclosed herein is an improved method for measuring the presence and amount of a variety of metals contained in a sample. In the first step, all of the various forms of each metal are converted to a soluble metallic complex which is capable of being electrochemically reduced. Voltammetry is then used to determine the stripping current or charge characteristic of each metallic complex. Finally, the concentration of each metal can be calculated by insertion of the stripping current or charge value into an equation which correlates peak current or charge values with metal concentration.The metals which can be detected and quantified by using this method are gold, silver, bismuth, cadmium, thallium, and mercury.

Abstract: An arrangement determines a voltage which indicates the lambda value of an air/fuel mixture supplied to a combustion engine generating exhaust gas during the operation thereof. The arrangement includes a two-cell oxygen probe mounted in the exhaust gas flow of the engine. The two-cell oxygen probe has an exhaust-gas space for the exhaust gas and an ambient-air space for ambient air. The oxygen probe has a pump cell having two electrodes and a sensing cell having two electrodes. A switchover stage outputs a voltage indicating the electric pump current through the pump cell when a control to the lambda value deviating from one is to be made and outputs that Nernst voltage which is taken off between the electrodes of the sensing cell facing into the ambient air and one of the remaining ones of the electrodes when a control to the lambda value one is to be made. For controlling to the lambda value one, the Nernst voltage supplies a significantly more precise signal than the voltage derived from the pump current.

Abstract: In an electrochemical detection method using an apparatus including a first vessel and a second vessel, a reference electrolytic solution in the second vessel, first and second closely spaced working electrodes immersed in a sample solution for measurement in the first vessel, a stripping electrode immersed in the reference electrolytic solution, and an ionic conductor arranged between the first vessel and the second vessel, the reference electrolytic solution contains an electrolyte which can be deposited and dissolved by an electrochemical reaction by applying a potential to the stripping electrode. In a first stage, a pre-electrolysis potential is applied to the first working electrode with the stripping electrode being connected to the second working electrode to deposit the electrolyte in the reference electrolytic solution on the stripping electrode.

Abstract: An electrolytic filter system (16) is disclosed for use in treating fluid provided by a fluid source(12) to a supplied environment (14). The system includes an electrolytic cell(18) controlled by control circuit(20). Various alternative constructions of the cell are described in which the effective separation of active electrodes, as well as the effective area of the active electrodes can be altered by a switching circuit (94) and controller (96) included in the control circuit (20). The controller responds to inputs from a current sensor (92) reflecting variations in the resistivity of the water. As a result, the controller is able to alter the effective separation and area of the active electrode, in response to resistivity variations to provide optimal operation.

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.

Abstract: An electrode assembly for use in quantifying the levels of various metals in an aqueous solution. In one embodiment, the electrode assembly comprises a substrate, the substrate being a silicon chip upon which a layer of silicon dioxide has been grown. A plurality of gold bond pads and gold interconnect traces are deposited by microphotolithography onto the silicon dioxide layer. An array of iridium deposits are then patterned by microphotolithography onto the interconnect traces at predefined locations. A passivation layer is deposited by plasma enhanced chemical vapor deposition over the finished metallization to electrically insulate it from external solutions. Plasma etching is then used to expose at least a portion of each of the iridium deposits. Just prior to analytical use, one or more of the exposed iridium elements are electroplated with mercury. The present invention is also directed to a field deployable sensor including the above-described electrode assembly.

Abstract: A method and apparatus for measuring the quality of a coating on a plate. The invention uses a method of measuring the impedance of a coating on a plate, which uses the steps of placing the coating on a plate in a chamber, and then placing a counter electrode in the chamber so that the coating lies between the plate and the counter electrode. A reference electrode is placed in the chamber so that the coating lies between the reference electrode and the plate, and the chamber is filled with a fluid with an ionic substrate. A potentiostat induces a voltage between the plate and the reference electrode, and the impedance of the coating is measured to determine the quality of the coating.

Abstract: An electrochemical sensor for fluid media with at least two electrodes, which are in contact with one another via an electrolyte and are accommodated in a housing. Many different sensor variants are attainable with a few, standardized components. The housing (1) includes a plurality of modules (4a, 4b; 4c-4m), which are placed next to one another, are designed as hollow bodies, and are connected to one another, wherein at least two lateral surfaces (9) of each module (4a-4m) are suitable for connection to additional modules (4a-4m), and at least two of the modules (4a, 4b; 4c-4m) accommodate one electrode (2, 3) each, and the hollow space (16) enclosed by the modules (4a, 4b; 4c-4m) is delimited from the environment by the two electrodes (2, 3), on the one hand, and by a partial area (17) each of the inner wall (5) of the modules (4a, 4b; 4c-4m), and is provided for accommodating the electrolyte (18).