A sensor element and fabrication method thereof, the sensor element includes: a main pump cell including an inner pump electrode facing a first inner space into which a measurement gas is introduced, an external pump electrode provided on an element surface, and a solid electrolyte therebetween; an auxiliary pump cell including an auxiliary pump electrode provided facing a second inner space, the external pump electrode, and the solid electrolyte therebetween; and a measurement pump cell including a measurement electrode, the external pump electrode, and the solid electrolyte therebetween. The inner pump electrode has a porosity of 10 - 25%, the auxiliary pump electrode has a porosity of 30 - 50%, a thickness ratio of both the electrodes is 1.0 - 4.0, and current flowing to the main pump cell has a current density of 0.05 - 0.5 mA/mm.sup.2 when the measurement gas has an oxygen concentration of 20.5%.

A gas sensor includes a gate electrode; a dielectric layer covering one surface of the gate electrode; an indium (In) gallium (Ga) zinc (Zn) oxide (O) (IGZO) thin-film formed over the dielectric layer, and first and second metallic electrodes formed on a surface of the IGZO thin-film to act as source and drain, respectively. The IGZO thin-film has an In concentration of 11%+/−3%, Ga concentration of 11%+/−3%, Zn concentration of 7%+/−3%, and 0 concentration of 71%+/−3%, with a sum of the concentrations being 100%, and the gas interacts with the IGZO thin-film and changes a current through the IGZO thin-film.

A connector includes two insulators which hold contacts connected to lead wires and are arranged on two surfaces of a base end portion of a ceramic element, two spring components which have flat plate portions located on respective outer surfaces of the two insulators and spring portions supported by the flat plate portions, and a cylindrical sleeve. Each spring portion has an inclined surface which inclines in a movement direction in which the sleeve moves toward the spring components. Each spring portion is elastically deformed by the sleeve hanging over the spring portion. The two insulators hold the base end portion from two sides by being pushed by the flat plate portions in directions in which the two insulators are brought closer to each other. The contacts are pushed against the terminal electrodes.

A connector includes two insulators which hold contacts connected to lead wires and are arranged on two surfaces of a base end portion of a ceramic element, two spring components which have flat plate portions located on respective outer surfaces of the two insulators and spring portions supported by the flat plate portions, and a cylindrical sleeve. Each spring portion has an inclined surface which inclines in a movement direction in which the sleeve moves toward the spring components. Each spring portion is elastically deformed by the sleeve hanging over the spring portion. The two insulators hold the base end portion from two sides by being pushed by the flat plate portions in directions in which the two insulators are brought closer to each other. The contacts are pushed against the terminal electrodes.

A gas sensor includes: a sensor element; a ceramic housing holding a rear end portion of the sensor element and provided with metal terminals electrically connected to the sensor element; and an elastic insulating member that is fixed in the rear of the sensor element and into which a plurality of lead wires electrically connected to the metal terminals are inserted. The elastic insulating member has one or more common spaces formed in a surface of the elastic insulating member that faces the ceramic housing. Two or more of the lead wires are arranged in each common space.

A gas sensor includes a first electrode, a gas detecting layer disposed on the first electrode, and an electric-conduction enhanced electrode unit being electrically connected to the first electrode and the gas detecting layer. The electric-conduction enhanced electrode unit includes an electric-conduction enhancing layer and a second electrode electrically connected to the electric-conduction enhancing layer. The electric-conduction enhancing layer is electrically connected to the gas detecting layer and is made of an electrically conductive organic material.

A gas sensor includes a first electrode, a gas detecting layer disposed on the first electrode, and an electric-conduction enhanced electrode unit being electrically connected to the first electrode and the gas detecting layer. The electric-conduction enhanced electrode unit includes an electric-conduction enhancing layer and a second electrode electrically connected to the electric-conduction enhancing layer. The electric-conduction enhancing layer is electrically connected to the gas detecting layer and is made of an electrically conductive organic material.

An exhaust sensor includes a sensing element with a ceramic sensing element substrate and a sensing element terminal which is electrically conductive and which is supported by the ceramic sensing element substrate such that the sensing element is configured to sense constituents of exhaust gases when exposed thereto. The exhaust sensor also includes a mating terminal which is electrically conductive and which is in electrical communication with the sensing element terminal. The mating terminal has a base material and a clad material bonded to the base material such that the clad material contacts the sensing element terminal and such that the clad material is located between the sensing element terminal and the base material, thereby providing the electrical communication. The clad material is an alloy which is less than or equal to 20% iron, greater than or equal to 40% nickel, and greater than or equal to 13% chromium.

An exhaust sensor includes a sensing element with a ceramic sensing element substrate and a sensing element terminal which is electrically conductive and which is supported by the ceramic sensing element substrate such that the sensing element is configured to sense constituents of exhaust gases when exposed thereto. The exhaust sensor also includes a mating terminal which is electrically conductive and which is in electrical communication with the sensing element terminal. The mating terminal has a base material and a clad material bonded to the base material such that the clad material contacts the sensing element terminal and such that the clad material is located between the sensing element terminal and the base material, thereby providing the electrical communication. The clad material is an alloy which is less than or equal to 20% iron, greater than or equal to 40% nickel, and greater than or equal to 13% chromium.

A hydrogen gas sensor with a substrate and a zinc oxide nanostructured thin film deposited on the substrate, wherein the zinc oxide nanostructured thin film has a lattice structure with a weight ratio of low binding energy O.sup.2− ions to medium binding energy oxygen vacancies in a range of 0.1 to 1.0, and a method of fabricating a gas sensor by thermally oxidizing a metal thin film under low oxygen partial pressure. Various combinations of embodiments of the hydrogen gas sensor and the method of fabricating the gas sensor are provided.