Abstract: A gas-detecting apparatus includes a measurement circuit including a gas sensor and a measurement instrument and a decision circuit. Detection cells, included in the gas sensor, each include a first electrode, a second electrode having a surface exposed from an insulation layer, and a metal oxide layer disposed between the first electrode and the second electrode. The resistance values of the detection cells are each allowed to decrease by a contact of gas containing hydrogen atoms with the second electrode. The measurement instrument monitors the resistance values of the detection cells. The decision circuit decides whether the gas is detected or not based on at least one change of the resistance values.

Abstract: A gas sensor includes: a first conductive layer; a second conductive layer including a first region having a first thickness and a second region having a second thickness larger than the first thickness; a metal oxide layer disposed between the first conductive layer and the second conductive layer, the metal oxide layer including a bulk region and a local region surrounded by the bulk region, a degree of oxygen deficiency of the local region being higher than that of the bulk region; and an insulation layer covering the first conductive layer, the second region of the second conductive layer, and the metal oxide layer and not covering the first region of the second conductive layer.

Abstract: A hydrogen sensor includes: a first electrode; a second electrode; a metal oxide layer disposed between the first electrode and the second electrode and including a bulk area and a local area; a first insulation film covering the first electrode, the second electrode, and the metal oxide layer and having an opening reaching the second electrode; and a second insulation film being in contact with the second electrode in the opening.

Abstract: A gas sensor includes an insulation layer and detection cells covered with the insulation layer. Each of the plurality of detection cells includes: a first electrode; a second electrode having a surface exposed from the insulation layer; and a metal oxide layer disposed between the first electrode and the second electrode. In each of the detection cells, a resistance value of the metal oxide layer decreases with a response time, which is different in each of the detection cells, when a gas containing a hydrogen atom comes into contact with the second electrodes.

Abstract: A gas sensor includes a first electrode having a first main surface and a second main surface opposite to the first main surface; a second electrode having a third main surface facing the second main surface and a fourth main surface opposite to the third main surface; a metal oxide layer disposed between the first electrode and the second electrode, and being in contact with the second main surface and the third main surface; and an insulating film covering at least a part of the first electrode, a part of the second electrode, and at least a part of the metal oxide layer. At least a part of the fourth main surface is exposed to gas which contains a gas molecule including a hydrogen atom. A resistance value of the metal oxide layer decreases when the second electrode is in contact with the gas molecule.