Evaluation of indium tin oxide based surface plasmon resonance sensor for near-IR applications

Surface plasmon resonance (SPR) based optical biosensors hold strong potential for high-speed detection of changes in optical properties resulting from the alteration of the chemical or biochemical composition of the analyte. Traditionally, noble metals have been investigated for such plasmonic properties, while alternative materials like metal oxides have recently attracted attention for the potential to be tuned for applications in different spectral regions. Our work in this paper was devoted to the design of a highly sensitive biosensor based on a conducting oxide, indium tin oxide (ITO), for sensing in the near infra-red (NIR) range, up to wavelengths as low as the ones used in telecommunications (~1.55 µm). The analysis of the sensor performance leads us to introduce a new performance parameter, the comprehensive signal quality factor of the SPR curve, which is valuable to assess the quality of sensing. Our results also demonstrate the effectiveness of rf-magnetron sputtered ITO material which has been less explored in literature for plasmonic applications.