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: 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: 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 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.

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 4 to 20 to bring the sensor resistance in CO and that in methane closer to each other and increase the selectivity from hydrogen.

Abstract: A package for mounting a semiconductor device comprises a base plate and a conductive layer laminated onto the base plate via an adhesive layer. The modulus of elasticity at 25.degree. C. of the adhesive layer is 10 kg/mm.sup.2 or less.