Performance enhancement of waveguide-coupled and metamaterial surface plasmon resonance sensors based on silver-bismuth ferrite and graphene

In this study, conventional SPR sensors based on silver (Ag)-graphene and waveguide-coupled surface plasmon resonance (WCSPR) sensors based on Ag-BFO (Bismuth Ferrite)-Ag-graphene with and without a metamaterial (Meta) layer are examined. The numerical results demonstrate a significant increase in the depth of the reflectance dip, detection accuracy, and electric field penetration depth caused by the use of the metamaterial layer in the considered structures. This effect is more significant in the WCSPR-type structure. Furthermore, adding a thin coating of titanium oxide (TiO2) to the base structures yields the best sensitivity with a minimum reflectivity (R-min)<0.01 and resonance angles of less than 80 degrees for all structures. The sensitivity of considered structures such as Ag-TiO2-graphene structure are 192 degrees/RIU, 232 degrees/RIU for Ag-BFO-Ag-TiO2-graphene, 280 degrees/RIU for Ag-Meta-TiO2-graphene, and 364 degrees/RIU for Ag-BFO-Ag-Meta-TiO2-graphene. With resonance angles below 80 degrees and R-min<0.02, the structures Ag-meta-TiO2-graphene and Ag-BFO-Ag-Meta-graphene acquired the most impressive sensitivity, with sensitivities and quality factors of 512 degrees/RIU and 514 degrees/RIU and 45.36 and 47.27, respectively. The proposed sensors can detect changes in the sensing medium as small as 0.001 RIU. Therefore, the proposed study is extremely promising and provides a new avenue in the fields of medical biology and chemistry, based on the findings achieved.

Automated summary

This study compares conventional SPR sensors based on Ag-graphene and WCSPR sensors based on Ag-BFO-Ag-graphene with and without a metamaterial layer. The results show that the addition of a metamaterial layer significantly increases the depth of the reflectance dip, detection accuracy, and electric field penetration depth. The best sensitivity is obtained by adding a thin coating of TiO2 to the base structures. The proposed sensors can detect changes in the sensing medium as small as 0.001 RIU.