Ultra-high precision refractometric sensing via metasurface-enabled visualized vector beam characteristics

Biosensors are indispensable tools for personalized, public, and global healthcare applications. State-of-the-art nanostructure empowered biosensors are able to achieve label-free detection of biomarkers by means of wavelength shifts, or intensity changes. However, these advanced sensor platforms suffer from the need for high-Q resonators, expensive measuring instruments, or complex data processing algorithms. Here, we propose what we believe to be a novel sensing metrology method capable of achieving ultra-high precision refractometric sensing via visualized vector field characteristics. The metasurface-enabled sensor platform is intricately designed to impart distinct phase shifts on the two spin components, thereby converting the refractive index disparity into visually discernible patterns of the generated vector beam. By analyzing the patterns, high-precision and real-time refractometric sensing can be directly read out without expensive instruments and complex data processing. Moreover, the detection precision and detection range of our visualized sensor platform are customizable, showing superior performance compared to the state-of-the-art counterparts. The designed sensing platform enables compact, ultra-high precision, and affordable refractometric sensing, holding significant applications in various fields such as biomedicine, environmental monitoring, and quantum sensing.