Gas sensor

A gas sensor for detecting a target gas to be measured 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 in an elongated plate shape, including an oxygen-ion-conductive solid electrolyte layer and a proton-conductive solid electrolyte layer, and having an insulator layer interposed between the oxygen-ion-conductive solid electrolyte layer and the proton-conductive solid electrolyte layer;
• 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 first diffusion-rate limiting path, on an inner surface of the internal cavity the oxygen-ion-conductive solid electrolyte layer and the proton-conductive solid electrolyte layer being present;
• an oxygen pump cell including:
• an intracavity oxygen pump electrode disposed on the oxygen-ion-conductive solid electrolyte layer in the internal cavity of the measurement-object gas flow cavity;
• and an extracavity oxygen pump electrode disposed at a position different from the measurement-object gas flow cavity on the base part and adjacent to the intracavity oxygen pump electrode via the oxygen-ion-conductive solid electrolyte layer;
• and
• a hydrogen pump cell including:
• an intracavity hydrogen pump electrode disposed on the proton-conductive solid electrolyte layer in the internal cavity of the measurement-object gas flow cavity;
• and an extracavity hydrogen pump electrode disposed at a position different from the measurement-object gas flow cavity on the base part and adjacent to the intracavity hydrogen pump electrode via the proton-conductive solid electrolyte layer, and
• the control unit comprises:
• a pump control part for controlling operation of the oxygen pump cell and the hydrogen pump cell;
• and
• a concentration calculating part for calculating a concentration of a target gas to be measured in a measurement-object gas, wherein
• the pump control part applies a predetermined voltage between the intracavity oxygen pump electrode and the extracavity oxygen pump electrode of the oxygen pump cell to make an oxygen pump current flow through the oxygen pump cell;
• and applies a predetermined voltage between the intracavity hydrogen pump electrode and the extracavity hydrogen pump electrode of the hydrogen pump cell to make a hydrogen pump current flow through the hydrogen pump cell;
• and
• the concentration calculating part calculates the concentration of the target gas to be measured in the measurement-object gas based on at least one of the oxygen pump current and the hydrogen pump current.