Dielectric measurements of nanoliter liquids with a photonic crystal resonator at terahertz frequencies
Dielectric measurements of nanoliter liquids with a photonic crystal resonator at terahertz frequencies
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DOI：
10.1063/1.4927242
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发表时间：
2015-07-20
影响因子：
4
通讯作者：
Klein, N.
中科院分区：
文献类型：
--
作者：
Hanham, S. M.;Watts, C.;Klein, N.
提出了一种基于光子晶体谐振器和微毛细管的高灵敏度太赫兹波段纳升液体样品复介电常数测量技术。通过使用毛细管将类似于4 nl的液体样品引入到由高电阻率硅光子晶体板中的L3谐振腔限制的谐振模式的电磁场中来表征液体。分别在100 GHz和类似于5800 GHz处监测谐振模式的谐振频率和空载Q因子的扰动，允许计算样品的介电常数。描述系统响应的微扰理论和准静态分析的基础上的毛细管内的电场的分析模型也被提出，并发现同意与有限元模拟和实验测量的各种浓度的乙醇-水混合物的液体样品的低到中等的损耗角正切。我们通过测量几种生物液体的复介电常数来证明这种方法的实用性，包括红细胞和白色血细胞的悬浮液。这些结果代表了在太赫兹频率下分析极少量生物，有毒，爆炸物和其他液体类型的芯片实验室设备的一步。(C)2015年作者。
We present a highly sensitive technique for determining the complex permittivity of nanoliter liquid samples in the terahertz band based on a photonic crystal resonator and microcapillary. Liquids are characterized by using a capillary tube to introduce a similar to 4 nl liquid sample into the electromagnetic field of a resonant mode confined by an L3 resonant cavity in a high-resistivity silicon photonic crystal slab. Monitoring the perturbation of the resonant frequency and unloaded Q-factor of the resonant mode at 100 GHz and similar to 5800, respectively, allows a sample's permittivity to be calculated. An analytical model describing the system response based on perturbation theory and quasi-static analysis of the electric field within the capillary is also presented and found to agree well with FEM simulations and experimental measurements of ethanol-water mixtures of various concentrations for low to moderate loss tangents of the liquid samples. We demonstrate the utility of this approach by measuring the complex permittivity of several bioliquids, including suspensions of red and white blood cells. These results represent a step towards a lab-on-a-chip device for the analysis of extremely small quantities of biological, toxic, explosive, and other liquid types at terahertz frequencies. (C) 2015 Author(s).