Ultrasensitive detection of traumatic brain injury biomarkers using a high- Q optical metasurface

Abstract

High- Q metasurfaces based on surface lattice resonances (SLRs) offer a viable route to mitigating the limited interaction volume of conventional near-field sensing by enabling stronger field confinement and enhancement within the sensing region. Here, we designed and fabricated a gold nanopillar array metasurface that simultaneously supports pronounced near-field enhancement and a high- Q resonance, with measured Q factors exceeding 200, and the refractive-index sensitivity reaches 319 nm/RIU. Moreover, in biomarker assays targeting BSA, S100β, and GFAP, the limits of detection were determined to be 8.46 fg/mL, 0.06 fg/mL, and 0.94 fg/mL, respectively. These results highlight the proposed SLR’s gold metasurface as a robust and generalizable nanophotonic sensing platform that combines high- Q resonances with practical bioassay performance for ultrasensitive, multiplex-compatible biomarker detection.