Gas sensor and method for manufacturing the gas sensor

摘要

A gas sensor comprises a gas detecting element (200) extending in a longitudinal direction and in which a plurality of ceramic layers are stacked, and wherein a detecting portion is provided at a leading end side of the gas detecting element (200).
The gas detecting element (200) comprises a first ceramic layer (211) having a first surface (211a) and a second surface (211b); a third ceramic layer (221) having a first surface (211a) and a second surface (211b) and having a third through hole (221h1) penetrating therethrough; a second ceramic layer (231) provided between the first surface (211a) of the first ceramic layer (211) and the second surface (221b) of the third ceramic layer (221) and having a second through hole (231h1) connected to the third through hole (221h1), the second through hole (231h1) having an opening area larger than that of the third through hole (221h1); a first connecting layer (213c) provided on the first surface (211a) of the first ceramic layer (211) and exposed in the second through hole (231h1); a second through-hole conductor (235d) provided on an inner peripheral surface of the second through hole (231h1); a second connecting layer (235f) having one end disposed on the first connecting layer (213c) and another end connected to the second through-hole conductor (235d); a third through-hole conductor (227) provided on an inner peripheral surface of the third through hole (221h1); and a third connecting layer (225c) provided on the second surface (221b) of the third ceramic layer (221) and connecting the second through-hole conductor (235d) and the third through-hole conductor (227).