Gas detection device, gas sensor system, fuel cell vehicle, and hydrogen detection method

A hydrogen detection method using a gas sensor,

• the gas sensor including:
• a first electrode;
• a second electrode;
• a metal-oxide layer that is disposed between the first electrode and the second electrode, and includes a bulk region and a local region surrounded by the bulk region, the local region having a degree of oxygen deficiency higher than a degree of oxygen deficiency of the bulk region;
• and
• an insulating film that covers the first electrode, the second electrode, and the metal-oxide layer, and has an opening that exposes part of a main surface of the second electrode,
• the hydrogen detection method comprising:
• detecting gas containing hydrogen atoms by detecting a decrease in a resistance value of the metal-oxide layer;
• determining whether the resistance value of the metal-oxide layer falls outside a predetermined range that is set within a range of resistance values of the metal-oxide layer before the gas contacts the second electrode, and
• when it is determined that the resistance value falls outside the predetermined range, applying a predetermined voltage between the first electrode and the second electrode to restore the resistance value of the metal-oxide layer back into the predetermined range.