Sensitivity Enhanced Plasmonic Biosensor Using Bi 2 Se 3 -Graphene Heterostructures: A Theoretical Analysis.

This study provided a theoretical insight for designing novel plasmonic biosensors using bismuth selenide (Bi 2 Se 3 )-Graphene heterostructures. It was a van der Waals (vdWs) stacked configuration composed of gold (Au) film, few quintuple layer (QL) Bi 2 Se 3 and few-layered graphene. In particular, the proposed biosensor was created by Goos-Hänchen (GH) shift rather than phase, resulting in a more sensitive biosensing response. Under the excitation of 632.8 nm, significant sensitivity enhancement performance was obtained via varying the thickness of Bi 2 Se 3 -Graphene heterostructures. The best configuration was 32 nm Au film-2-QL Bi 2 Se 3 -3-layer graphene, generating the largest GH shift, as high as -1.0202 × 10 4 µm. Moreover, the highest detection sensitivity was determined to be 8.5017 × 10 6 µm/RIU, responding to a tiny refractive index (RI) change of 0.0012 RIU (RIU, refractive index unit). More importantly, our proposed biosensor has shown a theoretical feasibility of monitoring virus samples. For example, there was an efficient linear detection range for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, 0~13.44 nanomole (nM)) and its Spike (S) glycoprotein (0~59.74 nM), respectively. It is expected that our proposed plasmonic biosensor has a potential application in performing sensitive detection of SARS-CoV-2.