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Fluid and microfluidic dielectric measurement using a cavity perturbation method at microwave C-band.

机译：使用腔扰动方法在微波C波段进行流体和微流体介电测量。

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摘要

The utilization of cavity perturbation technique in dielectric property measurement of fluid and micro-fluid is investigated in this thesis to better assist the ever-growing needs of science and technology for analysis and characterization of such materials in various applications from genetics, MEMS devices, to consumer product industry. Development of different techniques for measuring complex dielectric properties of fluid and micro-fluids at Giga (10 9)-Hz frequencies is of significant importance as their usage is increasingly coupled with infrared and microwave electromagnetic wavelengths. Conventional cavity perturbation method could provide a sensitive and convenient system for measuring fluids of low (e.g., epsilonr <10) permittivity that meets the assumptions of negligible perturbation to the electromagnetic field distribution in the cavity. Developing a methodology that uses conventional cavity perturbation method that is however suitable for a sensitive, accurate, and reliable measurement of high permittivity polar liquids at microwave C-band is the goal in the current work. Systematic studies are carried out, using de-ionic (DI) water as test specimens, to evaluate the influence of sample's container, volume, dimension, and temperature on the sensitivity and reliability of microwave dielectric measurement. The cavity perturbation measurement of DI water in a 1 mm diameter capillary tube showed well-defined temperature dependence of dielectric permittivity and loss coefficients of water. Observation of a permittivity peak in temperature range tested at 4GHz around -10 °C implies an important relaxation in low temperatures at microwave C-band, which corresponds to a critical slowing down of polarization reorientation in crystallized (icy) H2O. Numerical simulations using Finite Element Analysis (FEA) COMSOL suites were conducted to established the optimum amount of liquid water for cavity perturbation testing at microwave C-band (in perfectly conducting condition). The results showed at TE103 mode the tube D4= 4mm diameter (272 muL liquid volume capacity) provides the best measurement sensitivity in terms of resonant shift and low loss while for TE105 the 2mm 68 (muL liquid volume capacity) tube is the most promising. The experimental results yielded a shape factor of around 2 and 1 for epsilon' and epsilon", respectively. The examination of epsilon' and epsilon" interdependence using Kramers-Kronig concept showed the permittivity loss values is 4 times more dependent to the quality factor of resonant peak than permittivity. On the other hand, the dielectric permittivity dependence to resonant frequency was calculated around 2 times bigger than dielectric loss which signifies the importance of epsilon" in high loss liquid measurement by the cavity resonant perturbation method.
机译：本文研究了腔扰动技术在流体和微流体介电特性测量中的应用，以更好地满足科学和技术不断增长的需求，以分析和表征此类材料，从遗传学到MEMS器件，再到消费品行业。随着在千兆位（10 9）-Hz频率下测量流体和微流体的复杂介电特性的不同技术的发展具有重要意义，因为它们的使用越来越与红外和微波电磁波长耦合。常规的腔扰动方法可以提供一种灵敏且方便的系统，用于测量低介电常数（例如epsilonr <10）的流体，该流体满足对腔中电磁场分布可忽略不计的扰动的假设。当前工作的目标是开发一种使用常规腔体扰动方法的方法，该方法适用于微波C波段高介电常数极性液体的灵敏，准确和可靠的测量。使用去离子（DI）水作为测试样品进行了系统的研究，以评估样品容器，体积，尺寸和温度对微波介电测量灵敏度和可靠性的影响。在直径为1 mm的毛细管中去离子水的腔扰动测量表明，介电常数和水的损耗系数具有明确的温度依赖性。在-10°C左右4 GHz的温度下测试的温度范围内的介电常数峰值的观察结果表明，微波C波段的低温显着松弛，这对应于结晶（冰状）H2O中极化重新定向的严重减慢。进行了使用有限元分析（FEA）COMSOL套件进行的数值模拟，以确定在微波C波段（处于完全传导条件下）进行腔扰动测试的最佳液态水量。结果表明，在TE103模式下，D4 = 4mm直径（272μL液体体积容量）的管在共振偏移和低损耗方面提供了最佳的测量灵敏度，而对于TE105，2mm 68（μL液体体积容量）的管是最有前途的。实验结果表明，ε和ε的形状因子分别约为2和1。使用Kramers-Kronig概念检查ε和ε的相互依赖性，表明介电常数损耗值与质量因子的相关性高4倍。共振峰比介电常数大。另一方面，计算出介电常数对共振频率的依赖性大约是介电损耗的2倍，这表明在通过腔共振扰动法进行的高损耗液体测量中，ε的重要性。

著录项

  • 作者

    Asghari, Aref.;

  • 作者单位

    The University of Texas at San Antonio.;

  • 授予单位 The University of Texas at San Antonio.;
  • 学科 Materials science.;Electromagnetics.
  • 学位 M.S.
  • 年度 2015
  • 页码 59 p.
  • 总页数 59
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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