Fig. 1: Metamaterials-based spectral enhancement from UV to THz optical bands.

a Sensing applications of SEF spectroscopy. Left: A representative schematic of tumor-derived extracellular vesicles captured on the gold nanowell surface. Reproduced with permission¹⁰⁷. Copyright 2023, Wiley. Right: Lateral-flow immunoassay sensor based on metal-enhanced fluorescence. Reproduced with permission¹¹⁰. Copyright 2023, American Chemical Society. b Substrates and application of SERS. Left: Au Octahedral Nanoheptamers for SERS. Reproduced with permission¹⁴³. Copyright 2024, American Chemical Society. Right: Schematic illustration of the three-dimensional hexaplex-coated paper-based substrate sensor integrated with saliva collection tube for applications in human saliva sensing and lung cancer diagnosis. Reproduced with permission¹⁵⁴. Copyright 2024, Elsevier. c Metamaterials-based THz sensing. Left: Metallic hole arrays-complementary asymmetry split ring metamaterial with graphene integrated into the microfluidic cell for sensing applications. Reproduced with permission³⁰⁸. Copyright 2021, Elsevier. Right: Terahertz meta-biosensor for lung cancer detection. Reproduced with permission³⁰⁹. Copyright 2022, Elsevier. d Metamaterials for refractive index sensing. Left: Periodic Aluminum nanohole arrays for measuring cell growth. Reproduced with permission³¹⁰. Copyright 2021, American Chemical Society. Right: Optofluidic biosensors based on dielectric metamaterials for detecting extracellular vesicles by tracking the resonance wavelength or by the intensity change at a fixed probing wavelength. Reproduced with permission¹²⁵. Copyright 2021, Springer Nature. e Metamaterials for chiral sensing. Left: design of Born-Kuhn type plasmonic nanodimers to achieve sensitive response to analytes corresponding to expected circular dichroism. Reproduced with permission²⁰⁵. Copyright 2023, American Chemical Society. Right: A chiral plasmonic sensor composed of a racemic mixture of gammadions with no intrinsic circular dichroism (CD). Reproduced with permission¹⁹⁷. Copyright 2018, American Chemical Society. f Surface-enhanced infrared metamaterial. Left: Representative plasma nanoantennas. Reproduced with permission¹⁷³. Copyright 2023, Wiley. Right: Gradient high-Q dielectric metamaterial that comprises pairs of tilted Ge ellipses. Reproduced with permission¹⁸³. Copyright 2024, Wiley