Abstract: An insulator, airtightly supported via an annular metallic packing on a cylindrical housing, has a small-diameter portion and a large-diameter portion. A tapered surface extends in a radially outer direction from a small-diameter cylindrical surface to a large-diameter cylindrical surface. A receiving surface, formed on an inside wall of the housing, supports the tapered surface via the metallic packing. The tapered surface is brought into line contact with the metallic packing at its outer or inner circumferential portion.

Abstract: A method and apparatus for selectively removing oxygen from a gas stream containing NOx and oxygen by contacting the gas stream with an electrochemical cell made from an electrode consisting of La1-XMXFeO3, (where M is selected from the group consisting of Sr, Ba, Ca, and combinations thereof, and X is between 0.05 and 0.5), a solid oxide electrolyte and a counter electrode, wherein the La1-XMXFeO3 electrode is on one side of a solid oxide electrolyte, and a counter electrode is on the opposite side of the solid oxide electrolyte, and applying a voltage to the electrochemical cell. The apparatus is preferably employed in a two chambered NOx sensor utilizing solid electrolyte electrochemical cells, wherein an electrochemical cell capable of catalyzing oxygen reduction without catalyzing NOx decomposition is formed as integral to the first chamber.

Abstract: A method for detection of a bubble in a liquid which is placed in a measuring chamber and is in contact with a sensor for measuring the partial pressure of a particular gas in a liquid is provided. The method includes performing a first measurement of the partial pressure of the particular gas in the liquid at a first pressure in the measuring chamber. Next, the pressure in the measuring chamber is changed to a second pressure. A second measurement of the partial pressure of the gas in the liquid at the second pressure in the measuring chamber is performed. An expected result of the second measurement based on the first measurement and assuming that no bubbles are present in the measuring chamber during any of the measurements is provided. The actual result of the second measurement is compared with the expected result and a conclusion is drawn on the presence of a gas bubble in the liquid based on the comparison. An apparatus for measuring the content of a particular gas in a liquid is also provided.

Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected.

Abstract: The measuring range of a fuel cell based concentration sensor can be extended by decreasing the load across the fuel cell terminals and by increasing the amount of oxidant supplied to the fuel cell. In this way, such a sensor avoids saturation, for example, when measuring methanol concentrations from 0 M to over 4 M in liquid aqueous solution. Such a sensor is suitable for use in measuring fuel concentrations in the recirculating fuel stream of certain fuel cell stacks (for example, direct methanol fuel cell stacks).

Abstract: An electrochemical gas sensor. One embodiment of the sensor may include a sensor body having a cavity, an electrolyte solution in the cavity, an auxiliary electrode in contact with the electrolyte solution, a sensing electrode in contact with the electrolyte solution, and a first baffle mounted within the cavity. The baffle comprises a plate with at least one aperture and serves to form a partial barrier for delaying the mixing process when liquid is added to the electrolyte solution. The sensor may also include a second such baffle. Also a method for mixing a liquid with electrolyte solution of an electrochemical sensor. The method includes forming a first barrier within the cavity and controlling the flow of the liquid introduced through the first barrier. The method may include forming a second such barrier and controlling the flow of the liquid through the first and second barriers.

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

Abstract: A gas sensor is provided, for example, a sensor for determining the concentration or the temperature of a gas component. The gas sensor has a housing, in which a sensor element having at least one contact surface is arranged. The contact surface is conductively connected to a conductor element. The sensor element having the contact surface and the conductor element is arranged between two contact supports situated opposite one another. A spring element contacting the contact supports presses the conductor element onto the contact surface. Each of the contact supports, on sides facing one another, has at least one recess and at least one protuberance, the protuberance of one contact support engaging in the recess of the other contact support, and vice versa.

Abstract: Disclosed is a method for fabricating biosensors, using hydrophilic polyurethane. Bio-active reagents, including enzymes, antibodies, antigens, cells and receptors, are mixed with hydrophilic polyurethane and the mixture is directly coated over a signal transducer to form a sensing film which serves as a signal detector. The method using hydrophilic polyurethane allows the simplification of the fabrication of biosensors without conducting complicated chemical reactions and washing steps, such as crosslinking. The bio-active reagent entrapped within the hydrophilic polyurethane film can retains its high activity for an extended period of time and the intrinsic potentiometric response of the underlying ion-selective polymeric membrane is not affected by the bio-active reagent immobilized polyurethane film coated on its sensing surface. Therefore, the biosensors are superior in specificity, selectivity, and stability.

Abstract: The invention relates to a sensor for measuring ion concentration or gas concentration, with a gas- or ion-sensitive layer (6) that has two sensitive partial areas (20 and 21), two conducting areas (1b and 2b), each coupled capacitively through air gaps (9and 10) with one of the sensitive partial areas (20 and 21), with the capacitances of the couplings being different, and a comparison circuit (1a, 2a, 3, 4, 5) which has at least one first transistor (T1) connected with the first conductive area and a second transistor (T2) connected with the second conductive area, and at least one output at which a signal can be tapped that depends on the potential of sensitive layer (6).

Abstract: A gas sensor element is inserted into a housing having a base end and is fixed with respect to the housing. Terminal electrodes are provided on the base end of the sensor element. An atmosphere-side cover including an insulator with terminal accommodation holes is provided on the base end of the housing. The insulator also has an element accommodation hole (communicating with the terminal accommodation holes) in which the base end of the sensor element is placed. The insulator has ribs forming inner surfaces defining the element accommodation hole. The rib thickness is smaller than that of the sensor element base end. Metal terminals are at least partially placed in respective terminal accommodation holes and have connecting portions with leads for external electrical connection. The ribs are located between the metal terminals to form spaces between the metal terminals.

Abstract: A gas detector having a sealed sensor assembly is only exposed to the ambient atmosphere when the detector is to be placed in the service. The detector is placed in the service by removing an elongated planar adhesive backed sealing member. The gas sensor also incorporates a replaceable biomemetic sensing material which is carried within a housing within the detector. The housing contains an internal region wherein the gas sensing material is located. The internal region is sealed where the housing is attached to a printed circuit board on one hand and by the removable sealing planar member on the other hand so as to protect the gas sensitive material from contamination or exposure to the atmosphere until the unit is placed into service.

Abstract: A sensor is disclosed that comprises an electrolyte disposed between and in intimate contact with a sensing electrode and a reference electrode. A protective coating is disposed on the protective layer adjacent to the sensing electrode. The protective coating comprises a mixture of a metal oxide, a zeolite, and an alumina. A method for making the sensor is also disclosed.

Abstract: Temperature of a heater is controlled by switching an increasing rate of a resistance value of a heating unit of the heater. During a period T1 from a time point when heating of the heater is started until the resistance value of the heating unit reaches a reference value, the increasing rate is changed in multiple heating stages. In this manner, temperature and the resistance value of the heating unit are increased. During a period T2 from a time point when the resistance value of the heating unit reaches the reference value, feedback control is performed such that the resistance value is kept at the reference value as a target value.

Abstract: An amperometric electrochemical gas sensor includes a permanent electrical resistance means disposed between two electrodes, one of which is the working electrode, the electrical resistance means having an electrical resistance of between about 10&OHgr; and 200 k&OHgr;. This resistance means provides a permanent shorting link between the electrodes, and constantly maintains the sensor in a ready-to-work condition.

Abstract: An alcohol sensor having gas-sensitive layers made of polymers or inorganic oxides wherein a signal is read out by means of work function change which is produced in the form of a field-effect transistor.

Abstract: An amperometric electrochemical gas sensor includes a permanent electrical resistance means disposed between two electrodes, one of which is the working electrode, the electrical resistance means having an electrical resistance of between about 10 &OHgr; and 200 k&OHgr;. This resistance means provides a permanent shorting link between the electrodes, and constantly maintains the sensor in a ready-to-work condition.

Abstract: A method for making a sensor is disclosed, comprising mixing a metal oxide with a polymer to create a composition. The composition is applied to at least a portion of the sensing element comprising two electrodes with an electrolyte disposed therebetween, and calcined to form a protective coating. A gas sensor created in accordance with the above-referenced method is also disclosed.

Abstract: A method and apparatus for selectively removing oxygen from a gas stream containing NOx and oxygen by contacting the gas stream with an electrochemical cell made from an electrode consisting of La1-XMXFeO3, (where M is selected from the group consisting of Sr, Ba, Ca, and combinations thereof, and X is between 0.05 and 0.5), a solid oxide electrolyte and a counter electrode, wherein the La1-XMXFeO3 electrode is on one side of a solid oxide electrolyte, and a counter electrode is on the opposite side of the solid oxide electrolyte, and applying a voltage to the electrochemical cell. The apparatus is preferably employed in a two chambered NOX sensor utilizing solid electrolyte electrochemical cells, wherein an electrochemical cell capable of catalyzing oxygen reduction without catalyzing NOX decomposition is formed as integral to the first chamber.

Abstract: A gas sensor comprises: an electrochemical cell comprising an electrolyte disposed in ionic communication with a sensing electrode and a reference electrode, wherein the reference electrode comprises an inhibitor that reduces a first catalytic activity with selected sensing gas constituents without substantially affecting a second catalytic activity with oxygen; a heater disposed in thermal communication with the electrochemical cell; and at least one insulating layer disposed in contact with the heater. Methods for making and using the gas sensor with a selective reference electrode comprising an inhibitor are also disclosed.

Abstract: A electrochemical sensor for the detection of traces of HF and/or other acid gases in air, comprising a measuring electrode of an electrochemically active metal oxide powder, a reference electrode for fixing the potential of the measuring electrode close to the equilibrium potential of the oxidation/reduction system of MeOn/Mem+, and a counter electrode. The electrodes are in communicative contact with a hygroscopic electrolyte. The measured gas component changes the pH of the electrolyte, and thus the electrochemical equilibrium of the measuring electrode, to produce a measurable electrical current that is proportional to the concentration of the detected acid gas.

Abstract: Disclosed is a microchip-based differential-type potentiometric oxygen gas sensor, which comprises a working electrode and a reference electrode. The working electrode is composed of a cobalt-plated electrode, a buffered hydrogel, and an ion sensitive gas permeable membrane while the reference electrode is composed of an oxygen non-sensitive silver chloride electrode and the same ion-selective gas-permeable membrane of working electrode. By taking advantage of the corrosion potential, the microchip-based oxygen gas sensor can accurately and quickly detect the content of dissolved oxygen in a sample solution. With this structure, the oxygen gas sensor is applied to a microchip-based all potentiometric multi-sensor capable of detecting two or more ions and gas species on a single chip.

Abstract: The present invention is a method by which the deterioration judgement and the correction of an electrochemical carbon monoxide gas sensor are simply carried out without using the correction gas. The method of the present invention is that: the voltage is applied from the outside so that the working electrode of the electrochemical carbon monoxide gas sensor is operated as the negative electrode, and the counter electrode is operated as the positive electrode, and hydrogen is generated from the working electrode, and oxygen is generated from the counter electrode; after that, the potential of the working electrode and the counter electrode is returned to the operation potential as the sensor; and by using the reaction on the hydrogen remained in the vicinity of the working electrode, the sensor current is generated, thereby, it is tested whether the sensor is normally operated.

Abstract: Sensor for measuring the partial pressure of a gas in a gaseous medium, comprising an electrochemical cell (2) and a diffusion barrier comprising a porous membrane (10) situated above an orifice (7) made in a component surmounting a casing (1) enclosing said electrochemical cell (2).

Abstract: A gas concentration measuring apparatus is provided which includes a gas concentration sensor consisting of a pump cell, a sensor cell, and a monitor cell. The pump cell works to determine the concentration of O2. The sensor cell works to decompose an oxygen containing gas such as NOx and provide an output indicative of the concentration of NOx. The apparatus also includes an applying voltage determining circuit which looks up a predetermined voltage-to-current relation to determine a target voltage to be applied to the pump cell as a function of the current produced by the pump cell so as to preclude the pump cell from decomposing the oxygen containing gas component, thereby minimizing an error in determining the concentration of oxygen containing gas as a function of the output of the sensor cell.

Abstract: An electrochemical measuring cell for detecting hydrocyanic acid is improved in such a manner that a stable measurement signal is provided after a short time. The measuring cell includes a measuring electrode (1) of sintered gold and a counter electrode (2). A measuring cell housing (4) accommodates the measuring electrode (1) and the counter electrode (2). An electrolyte is in the measuring cell housing (4) and includes sulphuric acid with an additive of silver sulphate. A diffusion membrane (5) is disposed between the measuring electrode (1) and the substance to be detected.

Abstract: A gas sensor 1 includes a casing 10 which covers a sensing element 2 and includes two cylindrical members. The cylindrical members are axially disposed in such a manner as to overlap each other. Examples of the cylindrical members are a protector 11 (outer member) and a protector attachment portion 9a (inner member) of a metallic shell 9. A diameter-reduced portion 81 is circumferentially formed on the outer member 11 through, for example, caulking. A weld zone 83 is circumferentially formed at the diameter-reduced portion 81 so as to weld the outer member 11 onto the inner member 9a. Through formation of the diameter-reduced portion 81, a gap between the outer member 11 and the inner member 9a as measured at the position of the weld zone is reduced, thereby improving adhesion therebetween. As a result, possibility of a weld defect arising can be suppressed.

Abstract: An analyzer for continuously measuring the H2S content of a gas stream which utilizes a drying module for drying the gas, a compressor for compressing the gas, a means for diluting the compressed sample and an electrical chemical sensor. The invention is also a device for regulating the flow rate of air to a H2S oxidation system which utilizes the analyzer to control the ratio of air to H2S stream entering the process.

Abstract: A gas sensor (1) comprises: a pair of porous electrode layers (2b and 2c); a detector element (2) between the porous electrode layers (2b and 2c), wherein the detecting element (2) comprises an oxygen ion conductive solid electrolyte comprising zirconium oxide as a major component, and one of the porous electrode layers is a detecting-side electrode (2b) to be exposed to a gas to be measured; and a ceramic protecting layer (2p) covering the surface of the detecting-side electrode (2b), wherein the ceramic protecting layer (2p) comprises a magnesia.alumina spinel component, an excess magnesium oxide component not involved in the magnesia.alumina spinel component, and a zirconium oxide component.

Abstract: An electrochemical measuring sensor for determining gas components and/or gas concentrations in gas mixtures, having a sensor element which has at least one signal-forming electrode having a supply lead of the signal-forming electrode and at least one electrical element whose electrical potential differs from the electrical potential of the supply lead of the signal-forming electrode. The supply lead of the signal-forming electrode is at least regionally surrounded by an electrically conducting shielding, so that fault currents appearing because of the potential difference between the supply lead of the signal-forming electrode and the electrical element flow at least predominantly between the electrical element and the shielding.

Abstract: A sensing element, in particular for an electrochemical sensor for determining gas concentrations, having at least one three-dimensional electrode arrangement, applied on a support plate and forming trenches of a depth for measuring changes in capacitance and/or conductivity in a gas-sensitive layer arranged to a height in the trenches, the height of the gas-sensitive layer being less than the depth of the trenches.

Abstract: A gas sensor and a process are provided for manufacturing a gas sensor with an oxygen ion-conducting solid electrolyte, which has a measurement gas side and a reference gas side and which separates a measurement gas space from a reference gas space, at least one measurement electrode being arranged on the measurement gas side of the solid electrolyte and at least one reference electrode being arranged on the reference gas side of the solid electrolyte, and with a support which is gas-permeable at least in the area of the electrodes. The problem presents itself of providing an economical gas sensor, in which the gas supply to the electrodes takes place through a gas-permeable support, as well as providing a simple process for manufacturing the gas sensor. The problem is solved for the gas sensor in that the oxygen ion-conducting solid electrolyte and the electrodes are constructed as thin layers and are arranged on the gas-permeable support.

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

Abstract: The subject method and apparatus pertains to the accurate determination of a composition of gases, over a very wide range of compositions. The subject invention can utilize an ionic electrolyte (1), which separates gases of different compositions, a source of potential difference (2) which is applied across the ionic electrolyte, means for reversing the current, and means (3) for measuring the respective currents. The ratio of currents is a function of the ratio of the gas compositions on opposite sides of the electrolyte. By varying the applied potential, the sensitivity of the apparatus can be increased.

Abstract: A method for determining relative amounts of O2 and N2O in gas mixtures by quantitative electrochemical reaction including feeding a gas mixture containing O2 and N2O to a zinc-air cell having electrodes connected to a circuit consisting of a plurality of diodes and resistors, which circuit is set to have an electrochemical working range corresponding to each of the O2 and N2O; and measuring current flowing in the respective working range to determine the relative proportions of O2 and N2O in the gas mixture. An electrochemical cell including a casing capable of containing a gas mixture, including O2 and N2O a zinc-air cell in the casing, and a circuit connected to electrodes of the zinc-air cell, the circuit containing a plurality of diodes, resistors and tap points; means for measuring current to determine the relative proportions of O2 and N2O in the gas mixture.

Abstract: An objective gas to be measured is introduced into first and second chambers which are connected via a diffusion resistive passage. A first electrochemical cell is provided in the first chamber for pumping in and out oxygen in accordance with an applied voltage. A second electrochemical cell is provided in the second chamber and responsive to application of a predetermined voltage for generating a sensor current representing a specific gas concentration in the objective gas. The first electrochemical cell is located between the first chamber and a reference gas chamber so that oxygen pumping in and out operation can be performed between the first chamber and the reference gas chamber.

Abstract: Disclosed is a NOx gas detecting apparatus which is capable of detecting a NOx gas at a low concentration with high accuracy over a long period of time even if Au or impurities contained in exhaust gas adheres to a cathode of a NOx detecting cell, and which is excellent in startability and responsivity. The NOx detecting apparatus comprises an oxygen pumping cell for removing oxygen from a measurement gas, and a NOx detecting cell. The NOx detecting cell includes, as a cathode, a cermet electrode composed of a Pt-Pd alloy, a Pt-Au-Pd alloy, or a Pt-Pd-Rh alloy along with a ceramic component. An addition amount of Pd to the alloy is preferably from 1 to 90 wt %. A weight ratio of Pd to Au in the Pt-Au-Pd alloy is preferably not less than 1.67. An addition amount of Rh in the Pt-Pd-Rh alloy is not more than 30 wt %.

Abstract: A detector assembly for detecting a plurality of different properties at the same location at the same time is provided by integrating onto a single semiconductor substrate a first detector unit for measuring a first property and a second detector unit for measuring a second property. The first and second detector units can share, for example, a common element, such as a sensor device that can provide electrical output signals representative of, respectively, the first property and the second property. The common element can include a diaphragm with a pyroelectric element to provide a measurement of temperature and pressure.

Abstract: The present invention provides a combinatorial approach for preparing arrays of chemically sensitive polymer-based sensors which are capable of detecting the presence of a chemical analyte in a fluid in contact therewith. The described methods and devices comprise combining varying ratios of at least first and second organic materials which, when combined, form a polymer or polymer blend that is capable of absorbing a chemical analyte, thereby providing a detectable response. The detectable response of the sensors prepared by this method is not linearly related to the mole fraction of at least one of the polymer-based components of the sensors, thereby making arrays of these sensors useful for a variety of sensing tasks.

Abstract: A gas sensor includes a sensor element and a housing having an accommodation hole in which the sensor element is disposed. The housing has at an axial end thereof a cold crimped portion which cooperates with a shoulder portion of the accommodation hole to fixedly hold therebetween the sensor element. The cold crimped portion has an inward flange section, a hollow cylindrical section and a bent section between the inward flange section and the cylindrical section. The cold crimped portion is shaped so as to vary in thickness suddenly at or adjacent the bent section so that the cold crimped portion is assuredly bent at a predetermined position. A method of producing a gas sensor is also provided.

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 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: A microsensor for identifying a change in a characteristic of an environment having temperatures of up to approximately five hundred degrees Centigrade includes a substantially flat insulator layer made of silicon oxide. A base layer made of silicon is integrally attached to one side of the insulator layer and a support layer is integrally attached to the other side of the insulator layer. Together the base layer and the support layer stabilize the support layer which is only about one thousand angstroms thick. A sensor element is mounted on the exposed surface of the support layer, and opposite the insulator layer, to generate a signal in response to the change in the environmental characteristic. Additionally, there is an electronic element which is processed into the support layer. This electronic element is electrically connected directly with the sensor element to process the signal and indicate an appropriate response.

Abstract: A seal arrangement for a sensing element of a gas sensor, in particular for determining the oxygen content in exhaust gases of internal combustion engines, includes a packet made up of several seal elements, packed one on top of another, which immobilize the sensing element in a longitudinal bore of a metallic probe housing. A funnel-shaped diversion element lying in the axial direction of the sensor is integrated into the seal elements packed one above another in such a way that gas permeability between the diversion element and the inner wall of the probe housing is ensured. Toward the measured-gas end of the sensor, a small gap remains open between the sensing element and the diversion element.

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

Abstract: In this invention, a new, simple and small-size hydrogen-sensitive palladium (Pd) membrane/semiconductor Schottky diode sensor has been developed and fabricated. First, a high quality undoped GaAs buffer layer and an n-type GaAs epitaxial layer with the carrier concentration of 2.times.10.sup.17 cm.sup.31 3 is grown by molecular beam epitaxy (MBE) on a semi-insulated GaAs substrate. Then a thin Pd membrane is evaporated on the surface of the n-type GaAs epitaxial layer by the vacuum evaporation technique. It is well-known that palladium metal has excellent selectivity and sensitivity on hydrogen gas. When hydrogen gas diffuses to the Pd membrane surface, the hydrogen molecules will dissociate into hydrogen atoms. Some of the hydrogen atoms diffuse through the thin metal layer and form the palladium hydride near the metal-semiconductor interface. The hydride may effectively lower the work function of Pd metal.

Abstract: A biological gas sensor for measuring a carbon dioxide partial pressure in an alimentary canal while excluding the influences of hydrogen sulfide and/or weak acid is disclosed. The gas sensor comprises a sensor which has in the sensitive part thereof a bicarbonate buffer solution held by a gas permeable membrane and detects a carbon dioxide partial pressure based on the hydrogen ion concentration of the bicarbonate buffer solution, a liquid holding part which is formed of a gas permeable tube having in the inside thereof the sensitive part of the sensor, an isotonic solution which is held in the liquid holding part and is isotonic with the bicarbonate buffer solution, and a metallic member (e.g., a coil of copper wire) so that hydrogen sulfide entering the liquid holding part may react with the metal and precipitate.

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: Methods for determining the amount of volatile electrolyte present in an aqueous liquid sample comprise transferring the electrolyte from the aqueous liquid sample to an absorber solution across a gas-permeable membrane which is non-passable to the aqueous liquid sample and measuring the change in electrical conductivity of the absorber solution during the transfer period. The absorber solution contains a solute which enhances the transfer of the electrolyte. Apparatus for conducting such methods include an absorber solution containing a solute which enhances the transfer of the electrolyte.

Abstract: A CO gas sensor according to the present invention includes a gas collecting container for collecting a measured gas therein; a detecting section provided within the gas collecting container and having at least a pair of electrodes positioned through electrolyte; and a voltage applying apparatus for applying voltage to the detecting section. One of the electrodes of the detecting section is a detection electrode having the capability of adsorbing at least one of hydrogenous gas and CO gas when a voltage is applied and then oxidizing it. By introducing a measured gas into a gas collecting container of the CO gas sensor and carrying out electrolysis according to a potential sweep method or a pulse method with the measured gas being in contact with the detecting section, a CO gas concentration in the measured gas can be measured based on an electrical current value obtained at the detecting section and changes of the electrical current with elapse of time.