Terahertz Polarization‐Specific Sensing of Trace Virus Based on Halloysite Nanotubes‐Modified Microfluidic Biosensor

Abstract Terahertz microfluidic biosensors have obvious advantages in trace detection, but how to achieve high sensitivity and specific detection of tiny viruses is still a challenge. Herein, this study proposes a reflective THz microfluidic biosensor with functionalized halloysite nanotubes (HNTs) to realize the quantitative detection of the EV71 virus. The biosensor achieves a strong polarization conversion effect by cascading bilayer metasurfaces, while simultaneously modifying functionalized HNTs with a large surface area onto its structure to offer more adsorption sites for the EV71 viruses. Furthermore, the high refractive index of HNTs and the local field of metasurfaces can enhance the interaction between THz waves and biochemical substances. The experimental results show that the combination of HNTs and antibodies can enhance the specific enrichment of the EV71 virus, thus realizing the polarization sensing of trace samples, and the detection limit can reach 0.01 µg mL ⁻¹ . The results of control experiments also show that HNTs and antibodies play a key role in enhancing the sensitivity and specificity of virus sensing, with the highest detection accuracy increased by 2 and 3.2 times at 1 µg mL ⁻¹ , respectively. This study verifies the feasibility of THz polarization sensing and HNTs enhancement technology to detect viruses, providing a novel pathogen sensing paradigm.