Detection of nitrous oxide using infrared optical plasmonics coupled with carbon nanotubes

Interest in gas sensing using functionalised carbon nanotubes is a major area of research that utilises changes in their electrical properties induced by the reaction with a specific gas. This paper describes specific gas sensing on an optical platform consisting of a 2-dimensional nano-structured plasmonic array of nano-antennae/nanowires, with topological dimensions of mean radius of 130nm, typical length of 20µm and a period of 500nm. The array is created by the spatial compaction of germanium oxides when the material interacts with ultra-violet irradiance, it can support infra-red localised surface plasmons. Carbon nanotubes are deposited upon the surface of the plasmonic platform followed by the application of the polyethyleneimine polymer. The resulting nanomaterials–photonic platform gives rise to the selective response to nitrous oxide gases, which are a major contributor to atmospheric degradation. We achieve the device sensitivity up to 100% atmosphere of nitrous oxide with a detection limit of 109ppm, a maximum response time of nineteen seconds and yielding a full-scale deflection of +5.7nm. This work demonstrates that the optical properties of specific carbon nanotubes can be used in a wide range of sensing applications offering a new sensing paradigm.