Polaritonic silicon metasurfaces for deep-UV surface-enhanced spectroscopy

We present polaritonic metasurfaces based on silicon (Si) nanostructures for deep ultraviolet (DUV) spectroscopy. Si shows strong surface polariton resonance in the DUV range due to interband transitions, enabling strong field enhancement at the subwavelength scale. By employing a tadpole-like void metasurface design, we achieve strong field enhancement (~700-fold) at ~260 nm, with precise tunability through structural modifications. The metasurface shows strong enhancement for biomolecular autofluorescence and nanomaterial resonance Raman scattering. The great stability of the metasurface in common bioassay solvents also highlights its suitability for DUV biosensing applications. (Adv. Funct. Mater. 2025, DOI: 10.1002/adfm.202420439)