Gas sensing device

A method comprising:

• (a) providing a gas sensing device comprising:
• a first layer and a second layer separated from each other by a gas absorption layer, said first and second layers electromagnetically interacting with each other upon illumination with light within a light frequency range, said gas absorption layer being configured for passing said electromagnetic interaction and having a variable thickness which changes upon absorption of a gas in such a way that said electromagnetic interaction is detectably affected, wherein
• (i) the first layer is a nanoparticle layer provided for generating a surface plasmon resonance within a plasmon resonance frequency range upon illumination with light within the light frequency range;
• and
• (ii) the second layer is a quantum dot layer having an absorption spectrum overlapping with said plasmon resonance frequency range of said nanoparticle layer, said quantum dot layer showing photoluminescence in a photoluminescence emission frequency range upon absorption of energy within an absorption spectrum of said quantum dot layer;
• (b) illuminating said gas sensing device at a wavelength corresponding to a plasmon resonance frequency of said nanoparticle layer;
• (c) detecting a first quantum dot luminescence signal;
• (d) exposing said gas absorption layer to a gas;
• (e) illuminating said gas sensing device at said wavelength corresponding to said plasmon resonance frequency of said nanoparticle layer;
• (f) detecting a second quantum dot luminescence signal;
• (g) calculating a difference between said first quantum dot luminescence signal and said second quantum dot luminescence signal;
• and
• (h) calculating a gas concentration from said difference between said first quantum dot luminescence signal and said second quantum dot luminescence signal.