Gas detection element

1. A gas detection element for detection of a measurement target gas, the gas detection element comprising:

a gas detection layer including a chemochromic pigment, the gas detection layer having a first surface and also having adhesiveness; and

a spacer, wherein

the spacer is porous such that it is permeable to the measurement target gas and air, is disposed on the first surface of the gas detection layer, and

has an area in a plane parallel to the first surface of the gas detection layer that is smaller than an area of the first surface of the gas detection layer, and

a gap between the spacer and the gas detection layer is formed around a periphery of the spacer, the gap being an empty space fillable by the measurement target gas.

2. The gas detection element according to claim 1 , wherein the spacer is selected from a group consisting of:

paper made of pulp;

a non-woven fabric or a woven fabric, including fibers of an inorganic material selected from the group consisting of glass, ceramic, and metal, or including fibers of a polymer material;

a thermal diffusion sheet including an inorganic material selected from the group consisting of glass, ceramic, and metal, or including a polymer material;

a porous sheet including an inorganic material selected from the group consisting of glass, ceramic, and metal, or including a polymer material; and

a foam having connected pores.

3. The gas detection element according to claim 1 , wherein at least a part of an end surface of the spacer is exposed to outside.

4. The gas detection element according to claim 1 , wherein a periphery of the spacer is surrounded by the gas detection layer in top view.

5. The gas detection element according to claim 1 , wherein the spacer has a thickness in a range from 5 μm to 1000 μm.

6. The gas detection element according to claim 1 , wherein a ratio Ss/Sg is in a range from 0.02 to 0.9, in which Ss represents an area of the spacer and Sg represents an area of the gas detection layer in top view.

7. The gas detection element according to claim 1 , further comprising a release liner on the first surface of the gas detection layer.

8. The gas detection element according to claim 1 , further comprising a backing on a second surface of the gas detection layer opposite to the first surface.

9. The gas detection element according to claim 8 , wherein the backing is formed of polyimide, polyethylene (PE), polypropylene (PP), a fluorinated ethylene propylene copolymer (FEP), an ethylene tetrafluoroethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), or polyvinylidene fluoride (PVDF).

10. The gas detection element according to claim 1 , wherein the chemochromic pigment changes in color by contacting a reducing gas.

11. The gas detection element according to claim 1 , wherein the chemochromic pigment includes palladium oxide on surfaces of carrier particles, a noble metal other than palladium being carried by or doped into the palladium oxide.

12. The gas detection element according to claim 11 , wherein the carrier particles include titanium oxide.

13. The gas detection element according to claim 1 , wherein the gas detection layer includes a silicone resin.

14. The gas detection element according to claim 13 , wherein the silicone resin includes a phenylmethyl group or a dimethyl group.

15. The gas detection element according to claim 1 , wherein the gas detection element is in a form of a patch or in a form of a strip.

16. The gas detection element according to claim 1 , wherein the measurement target gas is hydrogen gas.

17. The gas detection element according to claim 1 , wherein the area of the spacer is substantially larger than an opening in an inspection member, and the measurement target gas is introduced through the opening.