Broadband Terahertz Fingerprint Metasurfaces via Localized Surface Plasmon Resonance and Electromagnetically Induced Transparency Synergy

We developed a terahertz broadband sensing chip based on the synergistic enhancement effect of localized surface plasmon resonances (LSPRs) and electromagnetically induced transparency (EIT). This chip consists of a periodic array formed by cross-shaped metasurface elements of varying sizes and E-shaped metasurface elements, enabling broadband biochemical substance detection within the 0.50–2.50 THz frequency range while maintaining high sensitivity and broad spectral fingerprint resolution capability. Through analysis of electric field distribution, surface current distribution, and multipole decomposition theory, the physical mechanisms underlying near-field localization enhancement and far-field scattering regulation were systematically revealed. Experimental results demonstrate that the sensor achieves the lowest experimentally detected concentration of 5 μg/mL for lycopene. The characteristic peak sensitivities, derived from the envelope variation rate, are 10.44 × 10−3 a.u./(μg/mL) and 2.67 × 10−3 a.u./(μg/mL), respectively. This chip exhibits significant advantages in trace biochemical substance detection and broadband fingerprint recognition, offering new insights for the in-depth application of metasurface technology in the biosensing field.