Dual channel D-shaped SPR sensor for efficient detection of change in refractive index of analytes

Over the past ten years, significant advancements have been made in the field of D-shaped Surface Plasmon Resonance (SPR)-based optical fiber refractive index (RI) sensors which can be effectively used in chemical, biological, and health monitoring applications. Among single and dual/multi-channel SPR sensors, single-channel SPR sensors require analyte filling, emptying, and cleaning stages which is time-consuming and expensive. This work focuses on the design and performance investigation of a dual-channel D-shaped SPR sensor that can be used for the efficient detection of changes in the RI of analytes between two channels. The finite element method is used for the performance evaluation of the designed sensor, where the RI of the analyte of one channel is kept constant and that of the other channel is varied to observe the effect of change in RI difference from the known value. The proposed sensor can effectively detect the RI of analytes in the range of 1.33–1.40. The maximum wavelength and amplitude sensitivities are found to be 46000 nm/RIU and 6.96 RIU -1 , respectively. In addition, it exhibits comparable wavelength and amplitude resolutions of 1.30 × 10­ −05 RIU and 1.75 × 10 −08 RIU, respectively with asymmetrical RIs in two channels. Besides, the single-channel D-shaped SPR sensor having the same design parameters as the dual channel shows the maximum wavelength and amplitude sensitivities of 44000 nm/RIU and -59.22 RIU -1 , with wavelength and amplitude resolutions of 2.27 × 10 −6 RIU and 1.01 × 10 −09 RIU, respectively. Thus, the designed dual-channel D-shaped SPR sensor has the provision for determining the RI differences of analytes, which could be used to check the consistency of RI among different batches of analytes for the same biological sample.