Designing Single- and Dual-Band EIT-Like Meta-Biosensors with T-Shaped Resonators for Specific Detection of Carcinoembryonic Antigens in the Terahertz Band

The biosensors based on metasurfaces have attracted significant attention for biological detection in the terahertz (THz) band due to the characteristics of rapid, label-free, and nondestructive. Benefiting from the low-loss characteristics of the electromagnetically induced transparency (EIT), we propose two single-band EIT meta-biosensors and a dual-band EIT meta-biosensor through various combinations of three designed T-shaped resonators that act as bright modes. By utilizing the excellent biocompatibility of gold nanoparticles (AuNPs), the proposed meta-biosensors modified with carcinoembryonic antigen (CEA) antibody-conjugated AuNPs achieve the specific detection of CEA within mixed tumor markers in the THz band, which indicates that the frequency shifts of the transparent peaks increase only with increasing CEA concentration, as the CEA antibody-conjugated AuNPs specifically capture the target antigens. Furthermore, we employ a mutual information feature extraction algorithm integrated with a support vector machine (SVM) to verify the discrimination of transmission spectra samples with different CEA concentrations, and the classification results show high intraclass consistency and clear interclass distinction. This work paves the way for the development of novel meta-biosensors with high sensitivity and specific target antigen recognition, which would provide technical support for cancer screening and disease diagnosis.