Light scattering in an integrated microfluidic waveguide cytometer

This dissertation presents a 2D cytometric technique for the study of light scattering from single scatterers. Compared with conventional 1D cytometric technique, this method gives a better understanding of the light scattering mechanism and is more useful for cellular diagnostics.;Finite-Difference Time-Domain (FDTD) simulations are applied in our cytometer to give 2D scatter patterns from biological cells. Experimental 2D scatter patterns are obtained from yeast and human Raji cells. These scatter patterns are compared with the FDTD simulations. Our results show that cellular microstructures generate fringes of scattered light, allowing the Fourier method to be applied to determine the yeast cell sizes. In the Raji cells the light scattered by the mitochondria dominates the scatter pattern, forming compact regions of high intensity that we term "small scale 2D structures". The analysis of these structures may ultimately be a useful diagnostic technique.;Mitochondrial aggregation in single cells is studied by FDTD simulations. Small angle forward scattering is used to differentiate normal cell models from cancerous ones. Fourier spectra of the wide angle side scattered light show that the highest dominant frequency can be used to determine cell sizes, while mitochondria contribute to lower frequency components.;In summary, we develop a 2D cytometric technique for the analysis of microscopic particles and biological cells. This technique has potential clinical applications such as detection of mitochondria-related diseases. With the advances of "lab-on-a-chip" techniques, a miniaturized inexpensive 2D cytometer can be of further interest.;An integrated microfluidic optical waveguide cytometer is developed. This addresses many interesting interdisciplinary issues such as integration of laser optics with a liquid-core waveguide and single particle immobilization in a fluidic flow. The operation of this cytometer is validated by performing analyses on polystyrene microbeads. The all planar structures without the need for an optical lens between the scatterer and the sensor simplify both the experiment and theoretical modeling of the system. The obtained 2D scatter patterns allow identification of the location of 90 degree scatter. Good agreement between experimental spectra and Mie theory simulations is obtained. A Fourier method is developed for microsize differentiation.