Abstract-High Electric Field-Enhanced Terahertz Metamaterials with Bowtie Triangle Rings: Modeling, Mechanism, and Carbohydrate Antigen 125 Detection

 

Ning Cui, Min Guan, Mengke Xu, Chenfeng Zhao, Hongyan Shao, Yang Zhang,  Yiping Zeng,

https://pubs.acs.org/doi/full/10.1021/acs.jpcc.1c05483

Spatial overlap between the electromagnetic field and analytes is a key factor to improve the sensitivity of label-free optical sensors. However, the overlap and sensitivity are limited by the plasma local field or the decaying resonant mode outside the cavity. In this paper, by constructing a bowtie triangle ring (BTR) metal microstructure array, a high electric-field enhanced terahertz (THz) metamaterials (MMs) absorber is proposed and demonstrated. By tuning the length and splits of the BTR structure, the greatly confined electromagnetic fields could be obtained in the channel, resulting in a significantly enhanced interaction between the analytes and terahertz. The split BTR (S-BTR) generates an additional dipole resonant, and the maximum calculating sensitivity of 498 GHz/RIU is obtained. Meanwhile, two kinds of THz MMs biosensors are fabricated and used to detect the breast cancer marker carbohydrate antigen 125 (CA125). The S-BTR has a resonance shift of 46.8 GHz (20 μg/mL), which is larger than the unbroken BTR (U-BTR). Therefore, the combination of electric-field enhancement with a dipole resonant could further improve the sensitivity of the MMs sensor. This BTR MMs sensor has great potential in the detection of proteins and small molecules.

Abstract-Design and application of terahertz metamaterial sensor based on DSRRs in clinical quantitative detection of carcinoembryonic antigen

Ning Cui, Min Guan, Mengke Xu, Weihao Fang, Yang Zhang, Chenfeng Zhao, and Yiping Zeng

(a) Schematic diagram of THz MMs biosensor chip; (b) Detection principle and the equivalent circuit for the DSRRs. (The capacitance of substrates and sample are expressed as 𝐶sub$C\text{sub}$ and 𝐶sam$C\text{sam}$, respectively. 𝐿𝑠$Ls$ is expressed as inductance of DSRRs.)

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-11-16834

The terahertz (THz) metamaterial biosensor has great potential for label-free and rapid specificity testing. Here, we designed two highly sensitive structures to detect the carcinoembryonic antigen (CEA) of the cancer biomarker in early stages. There was about 29 GHz (500 ng/ml) resonance shift for CEA with an insert grate metamaterial, which was consistent with simulation results. Moreover, the concentration of CEA was gained through the relationship between the cancer marker concentration and frequency shift (Δƒ). Our design and detection methods may provide a potential route for the early warning stages of cancer.

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