Plasmonic nanopatch array with integrated metal–organic framework for enhanced infrared absorption gas sensing

In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal–organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO₂) with high capacity. Experimental results show that this hybrid plasmonic–MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. The demonstration of infrared absorption spectroscopy of CO₂ using the hybrid plasmonic–MOF device proves a promising strategy for future on-chip gas sensing with ultra-compact size. (letter)