Subwavelength sensing elements from film-coupled silver nanocubes

The extreme sensitivity of the plasmon resonance excited between a silver nanocube and an Ag film to spacer layer thickness is utilised to create a novel sub-wavelength sensing element. Using the highly moisture-sensitive polymer Nafion we have created a sensor that responds to changes in humidity though a shift of the plasmon resonance. This architecture could be easily adapted to detect a variety of other gases.