Nitrogen-oxide gas sensor with long signal stability

A nitrogen-oxide gas sensor comprising:

• an oxide ion conductive solid electrolyte;
• a first film that contacts the solid electrolyte and is made of a p-type semiconductor metal oxide;
• a second film that contacts the solid electrolyte and is made of a p-type semiconductor metal oxide;
• an n-type semiconductor metal oxide that is included in at least one of the first and second films;
• a power source that applies electric power to the first and second films by electrically connecting a first node to the first film and a second node to the second film;
• a measurement unit that measures the electric potential difference between the first and second nodes;
• and
• a first electrode that is formed on a surface of the first film facing the solid electrolyte and is formed of a conductive metal.

A nitrogen-oxide gas sensor comprising:

• an oxide ion conductive solid electrolyte;
• a first film that contacts the solid electrolyte and is made of a p-type semiconductor metal oxide;
• a second film that contacts the solid electrolyte and is made of a p-type semiconductor metal oxide;
• an n-type semiconductor metal oxide that is included in at least one of the first and second films;
• a power source that applies electric power to the first and second films by electrically connecting a first node to the first film and a second node to the second film;
• a measurement unit that measures the electric potential difference between the first and second nodes;
• and
• a second electrode that is formed on a surface of the second film facing the solid electrolyte and is formed of a conductive metal.