Integrated nanophotonic metasurfaces via bound states in the continuum for next-generation biomedical sensors

Photonic bound states in the continuum (BICs) are non-radiative electromagnetic modes with ultrahigh quality factors that provide extreme light confinement and exceptional refractive-index sensitivity, making them highly attractive for advanced biosensing. Here we report recent progress in the development of integrated nanophotonic biosensors based on BIC-enabled all-dielectric metasurfaces. These large-area, optically transparent platforms support high-Q resonances can be functionalized with biomolecular recognition elements, including aptamers, proteins, and molecularly imprinted polymers, enabling highly selective detection of target analytes at ultralow concentrations down to the femtomolar regime. The combination of ultrahigh sensitivity, microfluidic compatibility, and scalable fabrication underscores the strong potential of BIC metasurfaces for applications in healthcare diagnostics, personalized medicine, and high-throughput bioanalytics. We demonstrate this capability through two representative applications: ultrasensitive detection of transforming growth factor-β (TGF-β) using molecularly imprinted polymers and quantitative analysis of SPARC-albumin interactions in a microfluidic platform. The sensor is based on an all-dielectric photonic crystal slab that exploits BIC-induced high-Q resonances to enhance light-matter interactions, enabling highly specific and sensitive biomolecular detection. The results represent promising routes toward further performance improvements and the next generation of nanophotonic sensing technologies.