Gas sensor

A gas sensor for detecting a hydrogen gas in a measurement-object gas, the gas sensor comprising a sensor element and a control unit for controlling the sensor element, wherein

• the sensor element comprises:
• a base part including a first solid electrolyte having proton conductivity, and a second solid electrolyte arranged at least partly in contact with the first solid electrolyte and having a lower resistance value of proton conduction than the first solid electrolyte;
• a measurement-object gas flow cavity having a gas inlet that opens on a surface of the base part;
• and an internal cavity that communicates with the gas inlet via a diffusion-rate limiting path, on an inner surface of the internal cavity at least the second solid electrolyte being present;
• a current measurement pump cell including:
• an intracavity measurement electrode disposed on the second solid electrolyte in the internal cavity of the measurement-object gas flow cavity;
• and an extracavity measurement electrode disposed at a position different from the measurement-object gas flow cavity on the base part, and adjacent to the intracavity measurement electrode via the second solid electrolyte;
• a reference gas chamber formed inside the base part, and being separated from the measurement-object gas flow cavity, on an inner surface of the reference gas chamber at least the first solid electrolyte being present;
• and
• a voltage detection sensor cell including:
• a reference electrode disposed on the first solid electrolyte in the reference gas chamber;
• and a detection electrode disposed at a position different from each of the reference gas chamber and the measurement-object gas flow cavity on the base part, and adjacent to the reference electrode via the first solid electrolyte or via the first solid electrolyte and the second solid electrolyte, and
• the control unit comprises:
• a pump control part for controlling the current measurement pump cell;
• and
• a concentration calculating part for calculating a hydrogen concentration in a measurement-object gas, wherein
• the concentration calculating part calculates the hydrogen concentration in the measurement-object gas based on an electromotive force generated in the voltage detection sensor cell;
• and/or calculates the hydrogen concentration in the measurement-object gas based on a current flowing through the current measurement pump cell.