Abstract: The filter of a gas sensor comprises an inorganic porous support supporting both an organic sulfonic acid compound including sulfo group (—SO3H) and a Lewis acid having at least a metal element of transitional metal elements, Al element, Ga element, In element, Ge element, and Sn element. The Lewis acid loaded in the inorganic porous support adsorbs low concentration siloxanes. The organic sulfonic acid compound including sulfo group polymerizes adsorbed siloxanes in the filter so as not to desorb from the filter.

Abstract: A gas sensor and the drive circuit for the sensor are installed within a mobile electronic device. The gas sensor is intermittently heated to an operating temperature for detecting gases and kept at an ambient temperature for other periods. When a sensor of the mobile electronic device detects that the device is placed in a closed space, the heating of the metal oxide semiconductor is halted. When the sensor detects that the mobile electronic device has been taken out from the closed space, the heating of the metal oxide semiconductor is resumed. The poisoning of the gas sensor by siloxanes or the like is prevented.

Abstract: An electrochemical gas sensor has a planar ceramic housing having a recess, a MEA, first and second electrically conductive gas diffusion membranes, and a metal lid fixed on the housing so as to cover the recess. The MEA is provided with an ionic conductive membrane, a first electrode on a surface of the membrane, and a second electrode on the opposite surface of the membrane. The first electrically conductive gas diffusion membrane is electrically connected to the first electrical connection. The second electrically conductive gas diffusion membrane is electrically connected to the second electrical connection. The lid presses the second electrically conductive gas diffusion membrane toward the MEA, and in the lid or in the bottom of the housing, a gas inlet is provided. The electrochemical gas sensor is easily made compact, small in the variations in the performances, and easily installed on a print circuit board.

Abstract: The output of the electrochemical gas sensor is amplified, and the ambient temperature is measured by means of a temperature sensor. When the ambient temperature is above or equal to a predetermined temperature, a standard value is generated and stored and is increased when the output of the amplification circuit is larger than the standard value, and a gas is detected according to the difference between the output of said amplification circuit and the standard value.

Abstract: An electrochemical gas sensor has a planar ceramic housing having a recess, a MEA, first and second electrically conductive gas diffusion membranes, and a metal lid fixed on the housing so as to cover the recess. The MEA is provided with an ionic conductive membrane, a first electrode on a surface of the membrane, and a second electrode on the opposite surface of the membrane. The first electrically conductive gas diffusion membrane is electrically connected to the first electrical connection. The second electrically conductive gas diffusion membrane is electrically connected to the second electrical connection. The lid presses the second electrically conductive gas diffusion membrane toward the MEA, and in the lid or in the bottom of the housing, a gas inlet is provided. The electrochemical gas sensor is easily made compact, small in the variations in the performances, and easily installed on a print circuit board.

Abstract: A CO sensor includes a solid electrolyte substrate, a sensing electrode, and a reference electrode, and outputs electromotive forces in accordance with CO concentrations. The sensing electrode and the reference electrode are provided on the same surface of the solid electrolyte substrate. The sensing electrode contains a metal oxide such as Bi2O3 that generates a positive electromotive force response when coming into contact with CO. The reference electrode contains a metal oxide such as CeO2 that generates a negative electromotive force response when coming into contact with CO.

Abstract: A gas is detected using a MEMS gas sensor. The electrical power to a heater in the gas sensor is changed between a low level, a high level suitable for detection of detection target gas, and a 0 level, and, therefore, poisonous gas is evaporated or oxidized at the low level, and the detection target gas is detected at the high level.

Abstract: A sensor body of an electrochemical gas sensor having no water reservoir is housed in a metal can including a sensing electrode on one surface of a proton-conducting membrane or a separator retaining an electrolyte and a counter electrode on the opposite surface thereof. The counter electrode is supported by and electrically connected to the metal can via a connecting member. The sensing electrode is connected to a diffusion control plate with the sensing electrode-side ring member, and the ring member is conductive and includes a hole at a center thereof that is connected to a hole of the diffusion control plate.

Abstract: A method and apparatus for diagnosing an electrochemical sensor that detects the concentration of a gas are operative for diagnosing whether or not the sensor is in an error state due to a rise in a resistance in the electrolyte of the sensor. Such detection is made on the basis of a current flowing between a sensing electrode and an opposite electrode or a voltage corresponding to the current. A method for diagnosing an electrochemical sensor having a solid or liquid electrolyte between a sensing electrode and an opposite electrode detects the concentration of the gas to be detected on the basis of a current flowing between the sensing electrode and the opposite electrode, or a voltage corresponding to the current. Whether or not the electrochemical sensor is in an error state is diagnosed on the basis of a resistance of the electrolyte between the two electrodes of the electrolyte.

Abstract: An electrochemical gas sensor includes: a disc-shaped metal bottom member; a cylindrical metal side member that extends along the axial direction of the bottom member to surround the bottom member; a ring-shaped polymer gasket that includes an opening in the center and in which both sides of the opening each have an L-shaped member in cross section, with one section of the L-shaped member being in contact with the inner side of the side member and the other section of the L-shaped member being in contact with the bottom member; a gas sensor body that is located in the opening of the gasket and whose bottom surface is in contact with the bottom member and that includes a pair of electrodes and a solid electrolyte membrane or a separator retaining a liquid electrolyte; and a metal cover that is in contact with the top surface of the gas sensor body.

Abstract: A MEA 6 having a proton conductive membrane is sandwiched by metal plates 14, 15 and they are further sandwiched by heat pressable films 20, 21. An opening 24 and an opening 18 are formed in the heat pressable film 20 and the metal plate 14, respectively so that an electrode 10 is used as the sensing electrode and exposed to atmosphere to be measured. Openings 25, 19 are formed in the heat pressable film 21 and metal plate 15, respectively so that an electrode 11 is used as the counter electrode, and water vapor is supplied to the electrode from a water pack.

Abstract: A proton conductor gas sensor whose durability at high temperature is enhanced by using gel not converted to sol even at high temperature in a water reservoir. Fine particles of silica are gelled by adding water thereto and agitating the mixture under shear force. The thus obtained gel (34) is placed in a water reservoir of proton conductor gas sensor (2) and fed through steam introduction port (30) to MEA (10).

Abstract: An aqueous solution of a Na salt of a phenol sulfonic acid polymer as a liquid electrolyte is held in a separator of a liquid electrochemical gas sensor. A sensing electrode and a counter electrode are connected to the separator to detect CO at a range from about ?40° C. to about 70° C.

Abstract: Water is stored in a metal can, and water vapor is supplied to a separator through an opening in a washer. The separator is an alkali metal salt in a sulfonated synthetic resin membrane, and KOH aqueous solution is used as the electrolyte, and the sensing electrode and the counter electrode are Pt—C, and solid proton conductive membranes are placed between the electrodes and the separator.

Abstract: An aqueous solution of a Na salt of a phenol sulfonic acid polymer as a liquid electrolyte is held in a separator of a liquid electrochemical gas sensor. A sensing electrode and a counter electrode are connected to the separator to detect CO at a range from about ?40 C.° to about 70 C.°.

Abstract: A test signal is applied in parallel with an electrochemical gas sensor for about ten seconds, while an amplifying circuit is turned off. After turning off the test signal, the amplifying circuit is turned on. If the gas sensor outputs an waveform of a predetermined shape in a predetermined period after the turning-on, the gas sensor will be judged to be normal.

Abstract: A proton conductor gas sensor whose durability at high temperature is enhanced by using gel not converted to sol even at high temperature in a water reservoir. Fine particles of silica are gelled by adding water thereto and agitating the mixture under shear force. The thus obtained gel (34) is placed in a water reservoir of proton conductor gas sensor (2) and fed through steam introduction port (30) to MEA (10).

Abstract: An electrochemical gas sensor is self-diagnosed on the basis of an output waveform that is generated when a power source of said gas sensor is turned on after said power source has been turned off for a short time and an output waveform that is generated when said power source is turned on after said power source has been turned off for a long time. In a normal gas sensor, when the power source is turned on after the power source has been turned off for the short time, a bottom will be generated in the potential of the sensing electrode side, and when the power source is turned on after the power source has been turned off for the long time, a peak will be generated in the potential of the sensing electrode side. A self-diagnosis of the electrochemical gas sensor can be done without pulse power source for self-diagnosis, and the dead time from self-diagnosis until start of detection can be shortened.

Abstract: A base is provided with a concave and three leads, and the central lead is bent to the side opposite to the concave, and the other leads are bent to the side of the concave. A central electrode of a sensor element is attached to the central lead and the bottom of the concave and a coil serving as both a heater and an electrode is attached to the other leads to support the sensor element on a small base at four points.

Abstract: A central electrode 12 is arranged in a coiled heater electrode 10. They are buried in a SnO2-based inner area 6, and the entirety is covered by a filter 8. The volume of the inner area 6 is set at from 1×10−3 mm3 to 16×10−3 mm3, the total volume of the bead 4 is set at from 15×10−3 mm3 to 70×10−3 mm3, and the ratio of the total volume of the bead 4 to the volume of the inner area 6 is set at from four to twenty to bring the sensor resistance in CO and that in methane closer to each other and increase the selectivity from hydrogen.