A Hybrid Metasurface Microfluidic Sensor Empowered by Quasi-Bound States in the Continuum for High-Sensitivity Biosensing

This paper reports a metal-dielectric hybrid metasurface biosensor operating via the quasi-bound state in the continuum (qBIC) mode. The proposed structure overcomes the limitations of weak field localization in alldielectric systems and high optical losses in plasmonic platforms. Experimental results with various analytes and concentrations demonstrate a maximum bulk refractive index sensitivity of$538.8 ~\text{nm} / \text{RIU}$, which aligns well with simulated predictions. When integrated with a microfluidic system, the sensor enables efficient analyte delivery to the sensing region, facilitating high-throughput, and quantitative biological detection. Furthermore, through surface functionalization, the device achieves rapid and specific detection of the SARS-CoV-2 spike protein. These findings highlight the potential of metasurface-based sensing platforms for applications in chemical analysis and health monitoring.