Department of Photonics, National Cheng Kung University, No. 1 University Road, Tainan 70101, Taiwan.
Department of Applied Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan.
Sensors (Basel). 2020 Nov 3;20(21):6268. doi: 10.3390/s20216268.
Gas sensing to recognize volatile liquids is successfully conducted through pipe-guided terahertz (THz) radiation in a reflective and label-free manner. The hollow core of a pipe waveguide can efficiently deliver the sensing probe of the THz confined waveguide fields to any place where dangerous vapors exist. Target vapors that naturally diffuse from a sample site into the pipe core can be detected based on strong interaction between the probe and analyte. The power variation of the THz reflectance spectrum in response to various types and densities of vapors are characterized experimentally using a glass pipe. The most sensitive THz frequency of the pipe waveguide can recognize vapors with a resolution at a low part-per-million level. The investigation found that the sensitivity of the pipe-waveguide sensing scheme is dependent on the vapor absorption strength, which is strongly related to the molecular amount and properties including the dipole moment and mass of a gas molecule.
通过在反射和无标记的方式下引导太赫兹（THz）辐射，成功实现了对挥发性液体的气体传感。管道波导的中空芯可以有效地将 THz 限制波导场的传感探头传送到存在危险蒸气的任何地方。目标蒸气会从样品位置自然扩散到管道芯中，然后基于探头和分析物之间的强烈相互作用进行检测。使用玻璃管实验性地描述了针对各种类型和密度的蒸气，THz 反射率光谱的功率变化特征。最敏感的THz 频率的管道波导可以识别具有低 ppm 级分辨率的蒸气。研究发现，管道波导传感方案的灵敏度取决于蒸气吸收强度，而蒸气吸收强度与分子数量和性质密切相关，包括气体分子的偶极矩和质量。
