Numerical investigation of IgG sensing through nanoscale topological-assisted metasurface for liquid biopsy

Abstract Topological photonics offers tightly confined, defect-immune optical modes ideal for biosensing, where sensitivity, spectral resolution, and fabrication tolerance must coexist. Conventional Guided-Mode Resonances (GMRs) sensors typically exhibit limited Q -factors, whereas high- Q photonic crystal cavities require complex fabrication and lack robustness. To bridge this gap, we present a refractive-index sensor based on a Jackiw-Rebbi topological resonance at the interface of two oppositely phased 2D GMR gratings. Under normal-incidence transverse-magnetic excitation, the device achieves Q > 1,600, bulk sensitivity of 97 nm/RIU, and a figure of merit (sensitivity × Q ) of 1.7 × 10 5 across 870–970 nm. The enhanced tolerance to fabrication deviations, together with high- Q , high-amplitude resonant behavior and a fully planar, photolithography-compatible geometry, makes the proposed topological GMR platform a strong candidate for next-generation label-free biosensing implementations.