Single-Walled Carbon Nanotube Terahertz Metasurface Sensor Based on Spoof Surface Plasmon Resonance

Terahertz (THz) spectroscopy technology, with its attribute of low photon energy, high penetration capabilities, and distinctive fingerprint spectral features, holds considerable promise for applications in noncontact and nondestructive detection. However, the weak interaction between THz waves and samples limits further improvement of the detection sensitivity of THz spectroscopy technology. In this article, leveraging the excellent electrical and optical properties of single-walled carbon nanotubes (SWCNTs) within the THz range, we propose a subwavelength periodic symmetric “I-shaped” metasurface. This metasurface incorporates both the substrate and a unite cell layer composed of SWCNTs as integral components of THz sensor structures. The enhancement phenomenon of THz waves interacting with matter based on the resonance effect of spoof surface plasmon excitations has been observed. Furthermore, sensing experiments were carried out by applying glucose solutions of varying concentrations onto the surface of the metasurface device, revealing a clear linear relationship between glucose concentration and THz resonance spectrum amplitude. This work provides a new approach for the detection of substances using carbon-based metasurface sensors.