Plasmonic hydrogen detection

A method of forming a plasmonic hydrogen detector that includes a structure, of a sensor, including a support and a plurality of nanostructure elements including a plasmonic material and a separate hydrogen sensitive material that is different from the plasmonic material, the method comprising:

• providing a source of incident radiation that emits incident radiation, the incident radiation in a wavelength range, the wavelength range being 500 nanometers (nm) to 900 nm;
• providing the sensor;
• and
• configuring the plurality of nanostructure elements on the support such that adjacent nanostructure elements are electromagnetically coupled such that, on interrogation by the incident radiation in the wavelength range, the electromagnetic field of one nanostructure element, of the plurality of nanostructure elements, spatially overlaps that of adjacent nanostructure elements, such that the structure is a plasmonic optical metamaterial;
• and
• configuring the hydrogen sensitive material to cause a change in permittivity of the plasmonic optical metamaterial in the presence of hydrogen;
• and
• detecting the change in permittivity using a permittivity sensor, the permittivity sensor operable to detect the change in permittivity of the plasmonic optical metamaterial in the presence of hydrogen.