Using Antibody Modified Terahertz Metamaterial Biosensor to Detect Concentration of Carcinoembryonic Antigen

An antibody modified terahertz (THz) metamaterial biosensor is proposed to detect the concentration of carcinoembryonic antigen (CEA). The biosensor has four metal split-ring-resonators (SRR) in a unit cell. The finite integration time domain (FITD) method is used to design and optimize the structure. The simulation shows that the biosensor is insensitive to incident angles and the sensitivity reaches to 76.5 GHz/RIU (Refractive Index Unit). The sample is manufactured using a surface micromachining process and characterized by a THz time domain spectroscopy (THz-TDS) system. The experimental results indicate that the resonant frequency of the biosensor decreases with the increase of the concentration of analytes on the surface. After that, the biosensor is modified with anti-CEA and used to detect the concentration of the CEA. Interestingly, the response of the biosensor depends heavily on the concentration of the Anti-CEA modified on the surface of the biosensor. When the concentration of Anti-CEA is 20 ng/ml, the resonant frequency shift shows good linearity to the concentration of CEA and the limit of detection (LOD) reaches to 0.1 ng/ml. This study paves a new way for sensitively detection of biomolecules, cancer biomarkers and immune responses, which is important for early stage diagnosis of cancers.