Plasmonic Nanograin Metasurface with Disorder‐Enhanced Biosensing for SARS‐CoV‐2 Variant and Antibodies

Abstract Recently, the concept of introducing disorder into ordered metasurfaces or periodic metastructures has shown great potential in improving their performance for light extraction, scattering, reflection, and radiation. However, its use in optical biosensing enhancement is still barely reported. Here, a kind of plasmonic biosensors based on disorder‐enhanced nanograin metasurfaces (DENMs) are proposed, and utilized for high‐sensitivity detection of SARS‐CoV‐2 Omicron variant and vaccine‐induced total antibodies. With the aim to elucidate the physics of short‐range‐disordered meta‐elements in long‐range‐ordered metastructures, the meta‐atom evolution is deduced from periodic nanohole metasurfaces to DENMs and totally disordered nanograin metasurfaces. It is found that the disorder of nanograin plays a critical role in elevating the DENM surface sensitivity of biomolecules. The DENM‐based biosensing demonstrates an extremely high diagnostic specificity with the probability P < 0.0001 on distinguishing the Omicron variant from other respiratory viruses. Moreover, these biosensors are used as a convenient tool to monitor vaccine efficacy for inoculators with the third booster injections. This study implies the promise of disorder‐enhanced metasurfaces on biomedical detection and will guide their applications on virus early discovery and prevention for future mobile healthcare.