| 摘要 |
An oxidizing gas sensor excelling in sensitivity to oxidizing gases. In particular, an oxidizing gas sensor comprising substrate (2) having space portion (21) provided in the direction of thickness thereof; insulating layer (3) provided on a surface of the substrate so as to cover the space portion (21); exothermic elements (5) provided in the interior of the insulating layer (3) at a position corresponding to the space portion (21); gas sensing element (4) provided on a surface of the insulating layer (3) at a position corresponding to the exothermic elements (5); and electrode pairs (6) provided in contact with the gas sensing element (4), wherein the gas sensing element (4) comprises thin-film sensing layer (41) composed mainly of tin oxide and air-permeable catalyst part (42) composed mainly of gold and provided on at least part of the surface of the sensing layer (41). It is preferred that the mass basis film thickness of the catalyst part (42) be in the range of 0.008 to 170 nm. Preferably, the sensing layer (41) has such a structure that columnar tin oxide crystal grains are agglomerated, the average minor axis diameter of the crystal grains being in the range of 7 to 65 nm.
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