Abstract: A gas sensor, disposed projecting from a wiring member serving as a mounting target and including a first wire and a second wire, the gas sensor detecting a gas that produces water in a case that the gas is combusted by being supplied with a voltage from the first wire and the second wire and measuring a resistance value using the first wire and the second wire, the gas sensor including a resistor holding a catalyst that facilitates combustion of the gas, a first electrode terminal connected between one end of the resistor and the first wire, and a second electrode terminal connected between another end of the resistor and the second wire, and the first electrode terminal and the second electrode terminal are fixed to each other and form a water vapor diffusion cavity.

Abstract: Object: To provide a gas sensor having a small size and that can suppress gas detection problems caused by frost using only a small amount of power. Solution: A first electrode terminal (12) includes at least one first connection part (121) connected to a first wire and a first arm part (123) extending from the first connection part (121) to one end (11a) of a resistor (11). A second electrode terminal (13) includes at least one second connection part (131) connected to a second wire and a second arm part (133) extending from the second connection part (131) to the other end (11b) of the resistor (11). The first electrode terminal (12) and the second electrode terminal (13) are fixed to each other and form a water vapor diffusion cavity (S2) extending from the resistor (11) to a wiring member or the vicinity of the wiring member, with at least part of the first arm part (123) and at least part of the second arm part (133) coated with insulation.

Abstract: A gas detection apparatus A comprises a signal processing circuit 20, a Wheatstone bridge circuit 21, integrating circuits 22 and 23, a differential amplification circuit 24, a direct current power supply circuit 25, a heater voltage application circuit 26. The Wheatstone bridge circuit 21 is configured of parallel combination of series circuits: one composed of a catalytic combustion type gas sensor 1 and a load resistor R1, and the other composed of a resistor R2, a variable resistor VR1 and a resistor R3. The heater voltage application circuit 26 is configured to generate a pulsed heater voltage by switching a direct current voltage of the direct current power supply circuit 25 through a transistor TR1 for applying the pulsed heater voltage to the Wheatstone bridge circuit 21. The integrating circuit 22 integrates a voltage at a connection point between the gas sensor 1 and the load resistor R1.

Abstract: A gas detection apparatus A comprises a signal processing circuit 20, a Wheatstone bridge circuit 21, integrating circuits 22 and 23, a differential amplification circuit 24, a direct current power supply circuit 25, a heater voltage application circuit 26. The Wheatstone bridge circuit 21 is configured of parallel combination of series circuits: one composed of a catalytic combustion type gas sensor 1 and a load resistor R1, and the other composed of a resistor R2, a variable resistor VR1 and a resistor R3. The heater voltage application circuit 26 is configured to generate a pulsed heater voltage by switching a direct current voltage of the direct current power supply circuit 25 through a transistor TR1 for applying the pulsed heater voltage to the Wheatstone bridge circuit 21. The integrating circuit 22 integrates a voltage at a connection point between the gas sensor 1 and the load resistor R1.