Gas sensor element, gas sensor, and production method thereof

A gas sensor which works to measure a given component of gas comprising:

• a gas sensor element including (a) an insulating ceramic member which has surfaces opposed to each other and a through hole formed therein, (b) a solid electrolyte body which is disposed in the hole of the insulating ceramic member and works to conduct to at least a given ion, the solid electrolyte body having a first major surface and a second major surface, (c) a measuring electrode disposed on the first major surface of the solid electrolyte body to be exposed to the gas, (d) a reference electrode disposed on the second major surface of the solid electrolyte body to be exposed to a reference gas, and (e) a heating element disposed on one of the opposed surfaces of the insulating ceramic member on the same side as the second major surface of the solid electrolyte body, the heating element working to activate the solid electrolyte body;
• a first and a second signal line leading to the reference electrode and the measuring electrode, respectively, for transmitting a sensor output to an external detection circuit;
• a first and a second conductor leading to the heating element for establishing electric connections with an external power supply control circuit to control supply of electric power to the heating element;
• and
• a housing in which the gas sensor element, the first and second signal line, and the power supply conductors are retained, the housing being designed to hold the gas sensor element to be exposed to the gas.

A gas sensor element production method comprising:

• forming an insulating ceramic member which is planar and made of an electrically insulating ceramic material, the insulating ceramic member having opposed surfaces and a through hole;
• forming a solid electrolyte body in the through hole of the insulating ceramic member, the solid electrolyte body being made of a ceramic material which conducts at least a given ion and having a first major surface and a second major surface;
• forming a measuring electrode disposed on the first major surface of the solid electrolyte body to be exposed to the gas;
• forming a reference electrode disposed on the second major surface of the solid electrolyte body to be exposed to a reference gas;
• arranging a heating element disposed on one of the opposed surfaces of the insulating ceramic member on the same side as the second major surface of the solid electrolyte body, the heating element working to activate the solid electrolyte body;
• preparing a hollow cylindrical ceramic member which is made of an electrically insulating ceramic material and has a closed end and an open end, the hollow cylindrical ceramic member also having a window formed in a peripheral surface thereof;
• wrapping the insulating ceramic member around the hollow cylindrical ceramic member with the reference electrode facing the window of the hollow cylindrical ceramic member;
• and
• firing the hollow cylindrical ceramic member around which the insulating ceramic member is wrapped.