ABSTRACTTERAHERTZ PHOTONIC CRYSTAL MICROFLUIDIC SENSORSByLaura Cecilia Acosta SilveiraChallenges associated with meeting needs in the pharmaceutical industry, environment monitoring and food safety are in the interrogation of small volumes of samples with high sensitivity and specificity. The use of terahertz (THz) sensors is of significant interest due to its rich spectral content. The key focus of this research is to demonstrate THz microfluidic sensors for use in continuous flow monitoring that provide high sensitivity while using small volumes of samples. In order to achieve high sensitivity, photonic crystal (PC) based structures operating at the THz spectral region, are examined. One dimension (1D) PC devices with and without defect layers are designed for continuous flow characterization of liquids and vapors. For further improvement of the sensing capabilities a 3D PC sensor is also examined. The devices are built using alternating high and low permittivity materials with characteristics (material properties and thicknesses) that regulate the THz wave through transmission. When the air region is filled with a higher permittivity sample such as a liquid or vapor, the THz wave transmission through the PC is altered. In contrast to conventional sample holders, the use of PC enhances the change in transmitted signal due to the sample being loaded into the air gaps in the PC. This sensing configuration allows for high sensitivity while using a small volume of samples. A material characterization method is developed for 1D PC based sensor in order to extract the corresponding samples dielectric properties. Details of design, fabrication and characterization of photonic crystal terahertz microfluidic sensors are presented in this thesis.
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