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.

中文翻译：

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利用抗体修饰的太赫兹超材料生物传感器检测癌胚抗原浓度

提出了一种抗体修饰的太赫兹 (THz) 超材料生物传感器来检测癌胚抗原 (CEA) 的浓度。该生物传感器在一个晶胞中具有四个金属裂环谐振器 (SRR)。有限积分时域（FITD）方法用于设计和优化结构。仿真表明，生物传感器对入射角不敏感，灵敏度达到76.5 GHz/RIU（折射率单位）。该样品使用表面微加工工艺制造，并通过太赫兹时域光谱 (THz-TDS) 系统进行表征。实验结果表明，生物传感器的共振频率随着表面分析物浓度的增加而降低。之后，用抗 CEA 修饰生物传感器并用于检测 CEA 的浓度。有趣的是，生物传感器的响应很大程度上取决于生物传感器表面修饰的 Anti-CEA 的浓度。当 Anti-CEA 浓度为 20 ng/ml 时，共振频移与 CEA 浓度呈良好的线性关系，检测限 (LOD) 达到 0.1 ng/ml。该研究为灵敏检测生物分子、癌症生物标志物和免疫反应开辟了一条新途径，这对癌症的早期诊断具有重要意义。