Abstract: A gas sensor includes a substrate, a heater member formed on the base member, a gas sensitive structure formed on the heater member by a process comprising the following steps of forming a stacked layer structure on the heater member, the stacked layer structure including at least a metal-oxide semiconductor layer and an insulating film, and carrying out a heat treatment with respect to the stacked layer structure so that a constituent of the insulating film is diffused in spaces among crystal particles of the metal-oxide semiconductor layer, and electrode layers are in contact with the gas sensitive structure.

Abstract: A gas sensor senses gas using a metal oxide semiconductor whose resistance changes depending on gas adhesion on a surface of the metal oxide semiconductor. The gas sensor includes a base structure, and a gas sensitive layer formed on the base structure and made of a metal oxide semiconductor. The gas sensitive layer has a multi-layer structure which includes at least two layer portions having mutually different grain structures.

Abstract: A gas detecting device includes a substrate and a plurality of gas sensitive elements supported by the substrate. A plurality of predetermined temperatures at which gases are detected are provided. The gas detecting device also includes a plurality of pairs of electrode leads supported by the substrate, each of the plurality of pairs of electrodes being connected to a corresponding one of the gas sensitive elements, and heater leads that are supported by the substrate and heat the plurality of gas sensitive elements so that each of the gas sensitive elements is set at a corresponding one of the plurality of predetermined temperatures.

Abstract: A gas detecting device includes a substrate and a plurality of overhang portions made from an electric insulation material and disposed in a space over the substrate. A gas sensitive film is made from a metallic oxide semiconductor material and is mounted on each of the overhang portions. A pair of detecting leads is connected to the gas sensitive film. A heater lead for heating the gas sensitive film is mounted on each of the overhang portions. The gas sensitive film of at least one of the plurality of overhang portions has a composition ratio of metal to oxygen different from that of the other gas sensitive films whereby a specified gas can be selectively detected on the basis of the response of the plurality of metallic oxide semiconductors to the gas.

Abstract: A gas detecting device includes a substrate, an insulator layer formed on the substrate, a gas sensitive layer formed the insulator layer, a pair of detection leads formed on the insulator layer, the gas sensitive layer partially overlying the pair of detection leads, a signal derived from the gas sensitive layer being sent to an external circuit through the pair of detection leads, a heater member arranged on the insulator layer in the vicinity of the gas sensitive layer, and an insulation coating layer formed on the pair of detection leads and the heater member, and partially overlying the gas sensitive layer so that the gas sensitive layer is put between the insulator layer and the insulation coating layer, and a portion of an upper surface of the gas sensitive layer is exposed to gas.

Abstract: A gas detecting device includes a substrate, an insulating layer supported by the substrate, first and second pairs of detection leads formed on the insulating layer, a heater lead formed on the insulating layer, the first and second pairs of detection leads being heated by passing a heater driving current through the heater lead, a gas sensitive layer formed of a gas sensitive material and provided so as to partially make contact with the first and second pairs of detection leads, and a passivation layer formed so as to cover the first and second pairs of detection leads and the heater lead. A gas detection signal is output from the gas sensitive layer through one of the first and second pairs of detection leads. A gas detecting system including the above gas detecting device is also provided.

Abstract: A gas detecting device includes a substrate, an insulator layer formed on the substrate, a gas sensitive layer formed the insulator layer, a pair of detection leads formed on the insulator layer, the gas sensitive layer partially overlying the pair of detection leads, a signal derived from the gas sensitive layer being sent to an external circuit through the pair of detection leads, a heater member arranged on the insulator layer in the vicinity of the gas sensitive layer, and an insulation coating layer formed on the pair of detection leads and the heater member, and partially overlying the gas sensitive layer so that the gas sensitive layer is put between the insulator layer and the insulation coating layer, and a portion of an upper surface of the gas sensitive layer is exposed to gas.

Abstract: A flow velocity sensor comprises a base, a first elongating member extending above the base and defined with a first edge at a downstream end thereof, a first heating device provided on the first elongating member along the first edge, a first heat detector provided on the first elongating member in a vicinity of the first heating device at a side away from the first edge and comprising a first metal oxide which absorbs oxygen when heated, desorbs oxygen when cooled, and changes resistivity responsive to adsorption and desorption of oxygen, a second elongating member extending above the base at a downstream side of the first elongating member and having a second edge at an upstream end thereof such that the second edge is substantially aligned with the first edge in a flow direction, a second heating device provided on the second elongating member along the second edge, and a second heat detector provided on the second elongating member in a vicinity of the second heating device at a side away from the second