A hydrogen gas sensor is configured such that an O-ring 21 is disposed
within
a measurement chamber 11a in order to seal against a first support
element 9a and against a proton conduction layer 1. This O-ring
21 assumes the form of a rectangular frame that surrounds a first electrode
3, and a substantially circular cross section, and is elastic, heat resistant,
and durable. A first metal plate 23a and a second metal plate 23b
are disposed from the outside on opposite support elements 9a and
9b, respectively. The hydrogen gas sensor of the present embodiment
has a pair of right-hand and left-hand through-holes 29 formed therein so
as to extend along the thickness direction thereof. Bolts 31 are inserted
into the corresponding through-holes 29. By fastening the metal plates 23a
and 23b from the outside by means of the bolts 31 and
nuts 33, the opposite support elements 9a and 9b
are fastened, thereby clamping the entire hydrogen sensor in a unitary condition.
