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theses

Multiplexing is a method of analyzing multiple analytes in a biological assay in a single step. It provides advantage of shorter processing time, low sample volume and reduced cost per test. Currently, Flow Cytometers are used for blood cells enumeration, however, they are expensive, requires fluorescent tagging of cells and trained technicians to operate the instrument. We propose a non-fluorescent microfluidic architecture with single excitation and detection scheme using the barcoded particles fabricated using Stop Flow Lithography process. The barcoded particles designed with specific number of coding regions can generate numerous distinct patterns of electrical signatures and can be used in biological assays to detect multiple blood cells.

A novel design of the asymmetric rectangular barcoded particle was proposed and tested in COMSOL Multiphysics. The barcoded particle with five coding regions generated distinct bi-polar signatures in the microfluidic impedance detection system. Different configurations of the sensing system were proposed to detect the conjugated microspheres (representative of blood cells) effectively based on the site of conjugation. The bottom co-planar electrode and top-bottom electrode configurations were tested for sensitive detection of conjugated microspheres to the barcoded particle. We found that our microfluidic detection system was sensitive enough to detect the presence of a microsphere attached to the barcoded particle. Further, we also investigated the effect of microspheres conjugation orientation to the barcoded particle and their associated electrical signatures. We developed a multi-feature selection algorithm to solve the orientation problem and improved the accuracy of our sensing mechanism. Finally, we fabricated the microfluidic chips using lithography, and co-planar electrodes on glass surfaces using thin film deposition process in the clean room. Our proposed microfluidic system can enumerate multiple blood cells in a single assay using barcoded particles. The concentration of these cells provides useful information about disease onset and progression. Such sensors can be used for diagnostic and management of diseases like Sepsis, Acute Kidney Injury, HIV/ AIDS.

ETD_10284

M.S.

Includes bibliographical references

doi:10.7282/t3-rax4-3a80

ETD graduate

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