Gas sensor and method for manufacturing the same

A gas sensor for determining a concentration of specific gases included in measurement target gases comprising:

• a measurement target gas chamber into which the measurement target gases are supplied
• a reference gas chamber into which reference gases are supplied;
• a solid electrolyte that has oxygen ion conductivity, and the solid electrolyte is disposed between the measurement target gas chamber and the reference gas chamber;
• a pump electrode and a sensor electrode that are formed on a surface at a side of the measurement target gas chamber on the solid electrolyte;
• and
• a reference electrode that is formed on a surface at a side of the reference gas chamber on the solid electrolyte,
• wherein the solid electrolyte, the pump electrode and the reference electrode constitute a pump cell for reducing an oxygen concentration of the measurement target gases,
• wherein the solid electrolyte, the sensor electrode and the reference electrode constitute a sensor cell for determining the concentration of the specific gases included in the measurement target gases of which the oxygen concentration is reduced by the pump cell,
• wherein the pump electrode includes Pt, Au and an aggregate,
• wherein in the pump electrode, a pore is set to be 5.2 vol % or less, a surface roughness Ra is set in the range of 0.5 μm to 9.1 μm, and a content ratio of the aggregate is set to be 4.9 vol % or more in a state that the pump electrode has not been heated to an activation temperature of the solid electrolyte yet after the gas sensor has been manufactured.