Abstract: An improved structure of a gas sensor is provided which is designed to provide for firm installation of the protective cover assembly on a cover mount of a housing. The cover assembly made up of an outer cylindrical cover and an inner cylindrical cover each of which includes an open end portion and a body portion. The body portion of the inner cylindrical cover is disposed within the body portion of the outer cylindrical cover in a non-contact fashion. The open end portion of at least one of the outer and inner cylindrical covers has a shoulder which is placed in line contact with the open end portion of the other cylindrical cover to secure portions of the outer and inner cylindrical covers installed on an end side wall of the housing.

Abstract: The invention is directed to an electrochemical measuring cell for detecting hydride gases, preferably arsine and phosphine. The measuring cell includes at least one working electrode (3) made of a catalytically inactive material and a reference electrode (4) in an electrolyte chamber (6) filled with an electrolyte containing sulphuric acid. The measuring cell is improved as to the cross sensitivity with respect to other toxic gases. The working electrode is configured as a carbon electrode (3) and an electrolyte additive of silver sulphate is provided in saturated solution in the electrode (9).

Abstract: An operational amplifier (34) has its inverting input connected to a electrochemical gas sensor (38) for amplifying the current produced thereby in response to presence of a predetermined gas. In order to determine whether a sensor (38) is indeed present and that a sensor present is serviceable, a transient is applied to the non-inverting input of the operation amplifier (34). The presence or absence of the sensor (38) alters the transfer function of the operational amplifier (34) in respect of the test signal. If a serviceable sensor (38) is present, the gain of the operational amplifier (34) is high for the transient resulting at square pulse output. However, if a serviceable sensor (38) is not present, the gain of the operational amplifier (34) is relatively low and the transient retains its original form. Consequently the presence of a serviceable sensor (38) can be determined from the output of the operational amplifier (34) in response to the transient test signal.

Abstract: An electrochemical sensor is described for the analysis of ammonia in air functioning in an amperometric measuring operation. The cell consists of either an immobilized organic electrolyte or a water based electrolyte having in both cases a dissolved Mn2+ salt, which is immediately oxidized by an electrochemical process at a measuring electrode of the cell to Mn4+ ion, if a pH-shift of the electrolyte in the presence of ammonia takes place. The sensor consists of three electrodes comprising a catalytic active carbon measuring electrode, a second carbon auxiliary electrode (counter electrode) in contact with the electrolyte and a third electrode in contact with the electrolyte, which acts as reference electrode. The sensor can be used for ammonia over a wide range and can be adapted for other uses, such as volatile amines.

Abstract: An electrochemical gas sensor including a sensor body having a cavity, an electrolyte in the cavity, an auxiliary electrode in contact with the electrolyte, a sensing electrode in contact with the electrolyte, and a blocking electrode in contact with the electrolyte. At least a portion of the blocking electrode is positioned intermediate the auxiliary electrode and the sensing electrode, and the blocking electrode reduces electroactive materials within the electrolyte. Also disclosed is a method for sensing a partial pressure of a target gas in a sample gas, the method including introducing the sample gas into a gas sensor, applying different potentials to the auxiliary electrode, sensing electrode and blocking electrode, reducing electroactive materials present in the electrolyte to prevent the electroactive materials from contacting the sensing electrode, and outputting an electrical signal from the gas sensor representative of the target gas partial pressure.

Abstract: The present invention provides an electrochemical sensor for the detection of hydrogen chloride. In general, the electrochemical sensor comprises a housing having disposed therein a working electrode, a reference electrode and a counter electrode. The electrochemically active surface of the working electrode preferably comprises a gold film having a thickness of approximately 1000 to 3000 .ANG.. Electrical connection is maintained between the working electrode and the counter electrode via an electrolyte present within the housing. The electrochemical gas sensor preferably further comprises circuitry for maintaining the working electrode at a potential in the range of approximately 1025 to approximately 1400 mV versus the normal hydrogen electrode. The present invention also provides a method of using such a sensor to detect hydrogen chloride.

Abstract: A simple, reliable, and leak-proof electrochemical sensor for detection of toxic gases. The sensor comprises a housing having an electrochemical gas sensor cell with an electrolyte and first and second electrodes bonded to conductive plastic. Each of the first and second electrodes is a membrane formed from a fluoropolymer film having a layer adhered thereto of a catalyst-impregnated fluoropolymer. The layers of each of said first and second electrodes are bonded to conductive plastic, and are separated by an absorbent material having an electrolyte absorbed therein. The sensor is particularly intended for detection of carbon monoxide, but may be used to detect other gases.

Abstract: A method and apparatus for measuring ethanol vapor concentration wherein a cell output is plotted with respect to time. The gradient of the steady rate portion of the plot is determined and an ethanol vapor concentration signal is generated from the determined gradient.

Abstract: A simple, reliable, and leak-proof three-electrode electrochemical sensor for detection of toxic gases. The sensor comprises a housing having an electrochemical gas sensor cell with an electrolyte and sensing, counter and reference electrodes bonded to conductive plastic. Each of the electrodes is a membrane formed from a fluoropolymer film having a layer adhered thereto of a fluoropolymer-impregnated catalyst. The layers of each of the electrodes are bonded to conductive plastic, and are separated by an absorbent material having an electrolyte absorbed therein. The sensor is particularly intended for detection of carbon monoxide, but may be used to detect other gases.

Abstract: An apparatus and method for sensing a concentration of oxygen in a flow of gas in a breathing circuit for a patient. A biasing voltage is provided across a zinc-air cell so that the zinc-air cell produces a current having a magnitude, wherein the magnitude of the current corresponds to the concentration of oxygen in the gas.

Abstract: The present invention provides an electrochemical sensor for the detection of hydrogen cyanide. In general, the electrochemical sensor includes a housing having disposed therein a working electrode, a reference electrode and a counter electrode. The electrochemically active surfaces of the working electrode and reference electrode preferably comprise silver. Electrical connection is maintained between the working electrode and the counter electrode via an organic electrolyte present within the housing. The electrochemical gas sensor preferably further comprises circuitry for maintaining the working electrode at a potential in the range of approximately +40 mV to approximately -40 mV versus the silver reference electrode. Most preferably, the electrochemical gas sensor comprises circuitry for maintaining the working electrode at a potential of approximately 0 mV versus the silver reference electrode. The present invention also provides a method of using such a sensor to detect hydrogen cyanide.

Abstract: The invention relates to an electrochemical sensor to determine the concentration of a gas to be quantified, comprising a housing, a measuring electrode comprising a catalystically active material which causes a reaction of the gas to be quantified, a counterelectrode comprising a carbon material, and a solid electrolyte in contact with the measuring electrode and the counterelectrode, wherein the solid electrolyte is prepared by swelling a solid matrix comprising an acrylate polymer with an electrolytic solution comprising at least one acid, and wherein the carbon material in the counterelectrode has a specific surface of at least 40 m.sup.2 /g and comprises reversibly oxidizable or reducible electrochemically active surface compounds.

Abstract: Accordingly, the present invention provides an electrochemical sensor comprising at least two electrochemically active electrodes, a non-aqueous electrolyte system and a diffusion barrier membrane through which the analyte in its gas phase is mobile but through which the non-aqueous electrolyte system is substantially immobile. The diffusion barrier membrane thus allows an analyte in its gas phase to enter the sensor, while substantially preventing the non-aqueous electrolyte from exiting the sensor.

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: A gas sensor including a substrate that is porous at least in a region thereof to permit permeation of gas. At least first and second porous electrodes are formed as planar elements on the substrate. The substrate is bonded to a housing in a peripheral area of the sensor. A portion of the first electrode extends into this peripheral area and is rendered non-porous to prevent the leakage of electrolyte therethrough.

Abstract: The present invention provides an electrochemical sensor for the detection of hydrogen chloride. In general, the electrochemical sensor comprises a housing having disposed therein a working electrode, a reference electrode and a counter electrode. The electrochemically active surface of the working electrode preferably comprises a gold film having a thickness of approximately 1000 to 3000 .ANG.. Electrical connection is maintained between the working electrode and the counter electrode via an electrolyte present within the housing. The electrochemical gas sensor preferably further comprises circuitry for maintaining the working electrode at a potential in the range of approximately 1025 to approximately 1400 mV versus the normal hydrogen electrode. The present invention also provides a method of using such a sensor to detect hydrogen chloride.

Abstract: The present invention provides an electrochemical gas sensor for the detection of nitrogen dioxide comprising a housing and a working electrode and a counter electrode disposed within the housing. Each of the working electrode and the counter electrode are fabricated from an electrically conductive carbon. The present sensor also preferably comprises a reference electrode fabricated from an electrically conductive carbon.

Abstract: The present invention provides an electrochemical sensor for the detection of an analyte, wherein the output or response of the electrochemical sensor approximates the dose-response behavior of a living organism upon exposure to the analyte. The electrochemical sensor comprises a housing including an inlet port therein to allow the analyte to enter the housing. The electrochemical sensor further comprises at least a first electrode and a second electrode within the housing. Electrical conductivity is maintained between the first electrode and the second electrode via an electrolyte system present within the housing. The electrochemical sensor further comprises a resistor in series electrical connection with the first electrode and the second electrode.

Abstract: An electrochemical measuring cell for detecting oxidizing gases, containing an electrode with a redox mediator, which is oxidized by the gas to be detected. A measuring electrode is employed made of an inert material, and a counterelectrode is provided. The dynamics and reproducibility of the measured signal are improved by providing the counterelectrode formed of an anodically oxidizable material and is arranged behind the measuring electrode in the direction of diffusion in a sandwich-like arrangement.

Abstract: An electrochemical measuring cell for detecting phosgene, with at least one measuring electrode made of silver and with a counterelectrode in an electrolyte, which contains an organic solvent and to which a conductive salt is added, is improved in terms of the detection of low concentrations of phosgene by adding an amine to the electrolyte.

Abstract: An electrochemical gas sensor comprises sensing and counter electrodes mounted on the same side of a planar support. An electrolyte is in contact with the sensing and counter electrodes. A capillary controls the access of gas to the sensing electrode. A barrier layer extends over the sensing and counter electrodes, the barrier layer being positioned relative to the capillary and the support being non-electrically conductive and being sufficiently porous such that gas from the capillary is guided transversely and laterally through the support first to reach the sensing electrode and then to reach the counter electrode.

Abstract: It is an of this invention to provide an electrochemical measurement cell capable of measuring the concentration of gaseous and charged or neutral compounds in a liquid. Accordingly, the present invention consists in one aspect in an electrochemical measurement cell having a working and a counter electrode surrounded by an electrolyte space filled with an electrolyte with a high viscosity, wherein the electrolyte space is at least partly delimited by a hydrophilic membrane. It has been surprisingly discovered by the present invention that charged or neutral compounds in a liquid, as well as gases, can be determined by means of an electrochemical measurement cell having a hydrophilic membrane and an electrolyte with a high viscosity.

Abstract: A gas sensor has at least a measuring electrode and a counter electrode on an electrolyte layer. This gas sensor is improved with respect to the complete extent of the electrochemical reaction achieved of the gas molecules, which are to be detected, at the measuring electrode by the manner of determining an electrical charge developed or accumulated thereat. To solve this task, the invention provides that the measuring electrode (14) has component electrodes (14a, 14b) which enclose the electrolyte layer (11, 12) in the manner of a sandwich.

Abstract: A sensing surface for a sensing cathode electrode useful in electrochemical gas sensors for sensing active gases in a gas mixture. The gas sensors are utilized in sensing oxygen or exhaust gases from a motor vehicle, so that there is a potential for causing deposits on the sensing surface of the electrode of either lead oxide species or lead carbonate thereon. The sensing surface is plated with rhodium or platinum for rejecting or prolonging the formation of any of the deposits thereon leading to an increase in rated life for the gas sensor greater than heretofore thought possible.

Abstract: The present invention pertains to an electronic measuring cell for detecting components in fluid media. Such a measuring cell is to be improved such that hermetic sealing of the contact wires leading out of the measuring cell is possible in a housing of a slightly modified design to prevent electrolyte from escaping. To achieve this, an annular space extending in parallel to the circumferential direction of the housing between the measuring cell cover and the housing is filled with an electrolyte- and temperature-resistant sealing material, and the contact wires are led through.

Abstract: An electrochemical, galvanic type, oxygen sensor including scavenging electrodes for continuously reacting any unreacted or partially reacted active gases, such as oxygen, to remove the active gases prior to being dissolved or have been dissolved in the electrolyte resulting in less than accurate output signals. The use of the scavenging electrodes permits the gas sensor to detect active gases in a gas mixture in sub-parts per billion level accurately and without the need for external sparging of the electrolyte with a pure inert gas. The liquid electrolyte may be stored in the a sol-gel medium formed in sensor container and holding the electrolyte in voids or pockets in the medium thereby rendering the oxygen sensor portable with the stored electrolyte and usable within a few minutes of operation.

Abstract: The present invention provides a low-cost alternative to currently available electrochemical sensors. In general, the present invention provides an electrochemical sensor for the detection of an analyte comprising a first metallic housing member and a second metallic housing member. The first metallic housing member and the second metallic housing member are brought together in sealed connection to create a sealed enclosure therebetween. Contained within the enclosure are a first electrode, at which the analyte reacts, and a second electrode, at which a reaction complimentary to the reaction of the analyte at the first electrode takes place. An acidic electrolyte is also contained within the enclosure of the first metallic housing member and the second metallic housing member.

Abstract: In this carbon monoxide sensor, particularly for measuring carbon monoxide in flue gases, which must be operated in a controlled-potential bias circuit and which comprises a working electrode, a counter electrode, and a reference electrode, all of platinum black, as well as an electrolyte connected with these three electrodes, the hydrogen cross-sensitivity is drastically reduced by providing two layers enriched by mercury and/or mercury ions, one on a surface of the working electrode and one of a surface of the reference electrode. These two electrodes are treated with mercury or a mercury compound before or after incorporation into the sensor.

Abstract: An electrochemical gas sensor assembly comprises an electrochemical gas sensor; an electrolyte reservoir (3); and at least one capillary (9) defined by substantially rigid, non-porous walls for conveying electrolyte between the reservoir and the gas sensor.

Abstract: A measuring device for determining the concentration of low-molecular alcohols in water or acid having the following construction:a porous anode for the electrochemical oxidation of alcohola cathode for the electrochemical reduction of oxygenan ion-conducting membrane arranged between the anode and cathodea diffusion-limiting membrane arranged on the side of the anode facing away from the ion-conducting membrane.

Abstract: A gas sensing assembly from which a number of gas sensing devices can be constructed for determining the concentration of an active gas in a gas mixture. The assembly comprises a self-contained sensing unit including a sensing element at which active gas reacts and is consumed, an output signal being produced proportional to the rate of reaction of active gas. A number of different control members are provided each defining a respective gas diffusion barrier, each member being separately securable to the sensing unit and detachable therefrom while leaving the sensing unit intact to enable gas sensing devices of different sensitivities to be constructed from the same sensing unit.

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: A sensor is proposed for detecting nitrogen oxides (NO, NO.sub.2, N.sub.2 O.sub.4) in a test gas, having a semiconducting metal oxide layer (3) which is deposited on a ceramic substrate (10) and whose electrical resistance provides information about the concentration of nitrogen oxides (NO, NO.sub.2, N.sub.2 O.sub.4) in the test gas. The main components of the sensor are a converter layer (4) which is deposited on the metal oxide layer (3) and is made of a material which causes the oxidation of combustible components of the test gas and converts the nitrogen monoxide (NO) contained in the test gas into nitrogen dioxide (NO.sub.2) or dinitrogen tetroxide (N.sub.2 O.sub.4), which then reaches the metal oxide layer (3), as well as a heating device (5) which heats the metal oxide layer (3) and the converter layer (4). The converter layer is suitably constituted of titanium oxide (TiO.sub.2) and/or zirconium oxide (ZrO.sub.2) and/or silicon oxide (SiO.sub.2) and/or aluminum oxide (Al.sub.2 O.sub.

Abstract: A biomedical sensor (20) is formed on a semiconductor substrate (22). Insulated dielectric layers (23, 24) are formed on the face and backside of the semiconductor substrate (22). Metal leads (26, 28) contact the substrate (22) through openings in the dielectric layer (23). The leads (26, 28) are also each connected to a set of interleaved longitudinal contact fingers (27, 29). A pair of contacts (30, 32) are formed on the opposite side of the substrate (22) from the contact figures (27, 29). A conductive biologic sample is placed over the interleaf fingers (27, 29), electrical measurements can be made through backside contacts (30, 32) so resistance measurements can be taken.

Abstract: Disclosed is an apparatus and method of equilibrating the dissolved gas composition of an aqueous fluid to reflect the predetermined gas composition contained in a gas equilibration reservoir. The equilibrated aqueous fluid can be used in a method of determining the concentration of a dissolved gas in a fluid sample. In one embodiment, the disclosed method is used to control the equilibrated gas composition of a calibrant fluid which, in turn, is used to measure the concentration of a dissolved gas, such as oxygen and carbon dioxide, in a sample fluid, such as whole blood.

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: Disclosed is an apparatus and method of equilibrating the dissolved gas composition of an aqueous fluid to reflect the predetermined gas composition contained in a gas equilibration reservoir. The equilibrated aqueous fluid can be used in a method of determining the concentration of a dissolved gas in a fluid sample. In one embodiment, the disclosed method is used to control the equilibrated gas composition of a calibrant fluid which, in turn, is used to measure the concentration of a dissolved gas, such as oxygen and carbon dioxide, in a sample fluid, such as whole blood.

Abstract: Disclosed is an apparatus and method of equilibrating the dissolved gas composition of an aqueous fluid to reflect the predetermined gas composition contained in a gas equilibration reservoir. The equilibrated aqueous fluid can be used in a method of determining the concentration of a dissolved gas in a fluid sample. In one embodiment, the disclosed method is used to control the equilibrated gas composition of a calibrant fluid which, in turn, is used to measure the concentration of a dissolved gas, such as oxygen and carbon dioxide, in a sample fluid, such as whole blood.

Abstract: An electrode sensor which may be used to specifically and quantitatively measure nitric oxide is provided, as well as a method of preparing and using such an electrode sensor to measure nitric oxide concentration in solution. A nitric oxide (NO) microsensor based on catalytic oxidation of NO comprises a thermally-sharpened carbon fiber with a tip diameter of about 0.5-0.7 .mu.m coated with several layers of p-type semiconducting polymeric porphyrin and cationic exchanger deposited thereon. The microsensor, which can be operated in either the amperometric, voltammetric or coulometric mode utilizing a two or three electrode system, is characterized by a linear response up to about 300 .mu.M, a response time better than 10 msec and a detection limit of about 10 nM. The sensor of the present invention also discriminates against nitrite, the most problematic interferant in NO measurements.

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: A sensor element for determining concentration of at least one constituent of a gas mixture operates on an electro-chemical measuring process and includes a gas measuring chamber; a pair of electrodes and an electrode chamber located between the pair of electrodes; and a diffusion conduit adjoining the electrode chamber and having a gas input which connects with the gas measuring chamber, having a gas output which connects with the electrode chamber, and having at least one cross-sectional area including a height, w, and a length, L, which height, w, has a preselected minimum value, and which length, L, has a value which is equal to or greater than the preselected minimum value of the height, w.

Abstract: The invention concerns a novel electrochemical sensor with which to measure gas concentrations and comprising a measuring electrode and an associated electrode containing a carbonaceous material with a specific surface of at least 40 m.sup.2 /g and with electrochemically active surface compounds which can be reversibly oxidized/reduced.

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 gas sensor comprises a substrate on which are mounted three cells. Each cell includes an interdigitated capacitor defined by a pair of comb structure, electrically conductive tracks with the fingers of the combs interleaved. The tracks of each capacitor are covered by an insulating and chemically inert protective coating of an electrolyte. A monitor monitors one of a resistive component and a capacitive component of the relative dielectric constant of the electrolyte independently of the other component.

Abstract: An amperometric sensor detects acidic and alkaline gases utilizing a first pH-dependent reversible redox system on a measuring electrode 4. A reduction current occurs between the measuring electrode 4 and a counter electrode 6 for a constant potential and is used as a measurement variable of the concentration of the gas to be detected. In addition, a reference electrode 5 is disposed in an electrolyte 7 together with the measuring electrode 4 and the counter electrode 6. The gas to be detected penetrates through the permeable membrane 2 and is dissolved while being dissociated. The amperometric sensor is improved with respect to its permanent stability. This is provided in that the first pH-dependent redox system is coupled to a second redox system and the redox potential of the second redox system is so selected that the reaction product is chemically regenerated again to the educt via the second redox system. The reaction product is electrochemically formed at constant potential by the first redox system.

Abstract: A polarographic sensor for determining concentration of certain components including oxygen or combustible fractions, such as hydrocarbons, hydrogen and carbon monoxide, in the exhaust gas of an internal combustion engine, includes a pump cell having an anode, a cathode, and an oxygen ion-conducting solid electrolyte provided between the anode and the cathode, wherein the cathode is provided with a diffusion barrier, wherein the anode is provided with a diffusion barrier, and wherein the concentration of the certain components is determined by measurement of a limiting current through the electrolyte and across one of the diffusion barriers to the corresponding anode or cathode.

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: An apparatus for detecting a given compound or changes in the concentration of such compound from a baseline concentration by means of a solid phase, film electrolyte, and being operable in a dissociative, galvanic or amperometric mode.

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.