Gas concentration measurement system and gas concentration measurement method

A gas concentration measurement system, comprising:

• a limiting current-type gas sensor;
• a voltage source connected to the limiting current-type gas sensor;
• a current detector connected to the limiting current-type gas sensor;
• and
• a gas concentration arithmetic unit connected to the current detector, wherein
• the voltage source is configured to supply a first voltage and a second voltage higher than the first voltage to the limiting current-type gas sensor,
• the first voltage generates a first limiting current corresponding to a first gas in the limiting current-type gas sensor,
• the second voltage generates a second limiting current corresponding to a second gas in the limiting current-type gas sensor,
• the current detector is configured to:
• acquire a first limiting current value of the limiting current-type gas sensor when the first voltage is applied to the limiting current-type gas sensor;
• and
• acquire a second limiting current value of the limiting current-type gas sensor when the second voltage is applied to the limiting current-type gas sensor,
• the gas concentration arithmetic unit includes circuitry configured to:
• acquire a difference between the second limiting current value and the first limiting current value;
• and
• obtain a concentration of the second gas on a basis of the difference, a limiting current-type gas sensor element comprising:
• a solid electrolyte,
• a first electrode disposed on the solid electrolyte,
• a second electrode disposed on the solid electrolyte,
• an insulating layer between the second electrode and the solid electrolyte, and
• a gas introduction path is a layer extending between a first part of the first electrode opposed to the solid electrolyte and a gas inlet,
• the insulating layer is disposed on each of:
• an upper surface of the solid electrolyte,
• a side surface of the solid electrolyte,
• a side surface of the first electrode, and
• a side surface of the gas introduction path, and
• the insulating layer includes an opening in which a second part of the second electrode contacts the solid electrolyte.