Wang Chen, Huang Yuxin, Zhou Ruiyun, Xie Lijuan, Ying Yibin
Opt Express. 2020 Apr 13;28(8):12001-12010. doi: 10.1364/OE.389517.
Terahertz (THz) spectroscopy has the advantages of non-ionization and spectroscopic fingerprint, which can be used for biological and chemical compound analysis. However, because of the strong absorption of water in the THz region, it is still a challenge for THz waves to realize aqueous solution detection. In this study, taking a doxycycline hydrochloride (DCH) aqueous solution as the target, we proposed a THz metallic mesh device (MMD) based reflection platform for the first time for sensing. The angle characteristics of the THz MMD was investigated through numerical simulations and experimental measurements to get an optimized configuration for the platform. When the projection of THz electric field polarization onto the MMD plane gets parallel to latitudinal direction of the MMD apertures, a strong resonant surface mode can be achieved, and our proposed platform can be successfully used to detect the DCH solution with a concentration as low as 1 mg L. The sensing mechanism of our platform was also explored by analyzing the influences of the immersion depth into the MMD holes and the extinction coefficient of droplets on the reflection spectra. Our work presents a rapid, low-cost, and practical platform for antibiotic solution sensing using THz radiation, which opens new avenues for the microanalysis of chemicals or biomolecules in strongly absorptive solutions in the THz region.
太赫兹（THz）光谱具有非电离和光谱指纹的优势，可用于生物和化合物分析。然而，由于太赫兹波段水的强吸收特性，太赫兹波实现水溶液检测仍是一项挑战。在本研究中，我们首次以盐酸多西环素（DCH）水溶液为目标，提出了一种基于太赫兹金属网器件（MMD）的反射式传感平台。通过数值模拟和实验测量研究了太赫兹MMD的角度特性，以获得该平台的优化配置。当太赫兹电场极化在MMD平面上的投影与MMD孔径的横向平行时，可实现强共振表面模式，我们提出的平台能够成功检测浓度低至1 mg/L的DCH溶液。通过分析MMD孔内的浸入深度和液滴消光系数对反射光谱的影响，还探究了我们平台的传感机制。我们的工作展示了一种利用太赫兹辐射进行抗生素溶液传感的快速、低成本且实用的平台，为太赫兹区域强吸收溶液中的化学物质或生物分子的微量分析开辟了新途径。
