Design and analysis of a highly sensitive surface plasmon resonance refractive index multi-channel sensor for multi-analyte sensing in visible to near-infrared region

Abstract

Photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensors have a unique sensing capability and can be applied over a wide refractive index (RI) range. In this research work a simple yet highly sensitive multi-channel hexagonal PCF based SPR RI sensor for detecting multiple analytes has been put forwarded. The target analytes and the plasmonic materials, such as, gold (Au), Au with Tantalum Pentoxide (Ta􀬶O􀬹) and Au with Titanium Dioxide (TiO􀬶) are employed around the exterior of the sensor for the feasibility of the operation. Twelve circular air-holes in two layers constitute the PCF structure which makes the fabrication process easy and realizable. Numerical investigations are carried out employing a full-vector finite element method (FEM) of COMSOL Multiphysics to obtain the sensing performance of the PCF-SPR structure. After optimizing the structural parameters, the sensor achieves maximum wavelength sensitivity (WS) of 38100 and 21600 nm/RIU, for channels-1 and 2, respectively. For channel-3, the sensor achieves a maximum WS of 45800 nm/RIU. To the best of our knowledge, the proposed sensor achieves better performance in terms of wavelength sensitivity, wavelength resolution, amplitude sensitivity, amplitude resolution, figure of merit, etc., compared to the existing literature. Overall, the sensor achieves RI range of 1.36 to 1.42 and within which many analytes samples fall. As a specific application, this multi-channel sensor may be employed to detect cancerous cells. In the case of cancerous cell detection, the proposed sensor achieves maximum WS and amplitude sensitivity of 12000 nm/RIU and -2440.30 RIU􀬿􀬵, respectively, for HeLa cells. It is envisaged that the proposed sensor has a high potential to detect unknown RI for different chemical and biomedical applications due to its superior performance, simple design, and multi-analyte detection ability.