Au-strip's shape dependent performance of D-shaped SPR based sensors

Abstract

D-shaped Surface Plasmon Resonance (SPR) based sensors show great promise for detecting different analytes with improved sensitivity and resolution. This work focuses on the investigation of the effect of gold (Au) strip's shape on the performance of D-shaped SPR sensor having a single mode germanium (Ge) core and microfluidic channel for analytes. Three different designs of Au strips namely, flat (design A), parabolic (design B), and combined (design C) having mixing of small flat and parabolic strips are considered here. The detailed numerical investigations are performed for all the designs using the finite element method. The highest wavelength and amplitude sensitivities are found to be 44 μm/RIU and 115.85 RIU−1, respectively at a resolution of 2.27 × 10−06 for the parabolic-shaped Au strip (i.e., design B). Alternately, design A shows reduced wavelength and amplitude sensitivities of 13 μm/RIU and 51.43 RIU−1, respectively with a resolution of 7.69 × 10−06. Similarly, design C reveals the wavelength and amplitude sensitivities of 14 μm/RIU and 45.01 RIU−1, respectively with a resolution of 7.14 × 10−06. Thus, the sensitivity of D-shaped SPR based sensors could be tuned significantly by modifying only the shape of the metal strip. This analysis would be useful in designing highly sensitive SPR based sensors.