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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/3919

Title: Microfabricated quantum dot linked immuno-diagnostic assay (QLIDA) biosensor with electrothermally accelerated biomolecular binding
Authors: Yu, Chengjie
Keywords: Biomedical engineering;Immunoassay--Quantum dots;Biosensors--Optical properties
Issue Date: Dec-2011
Abstract: Optically transduced microfluidic immunoassays have proven to be a highly sensitive and rapid method to assess the concentrations of analytes in a biological fluid. Although microfluidic immunoassays facilitate higher throughput and automation than standard microtiter plates, the immunoreaction within such devices remains diffusion-limited unless the analyte concentration is high enough to compensate the diffusion limit. We aim to circumvent this issue and accelerate the immunoreaction by developing a microfluidic immunosensor with an integrated set of electrodes to facilitate perpendicular electrothermal flow due to joule heating. In this work, 1) particle behaviors under AC electrohydrodynamic conditions, especially eletrothermal effect (ETE), has been studied, and 2) microfluidic biosensor devices with electrothermal mixing elements have been designed and developed. The Maxwell stress tensor method was used to understand dielectrophoretic particle-particle interactions. We applied the results of this to the interpretation of particle behaviors under dielectrophoresis (DEP) and electrothermal effect (ETE) conditions. Distinct particle behaviors ETE are presented and analyzed. Moreover, diverse particle-particle interactions are observed in experiments. These include particle clustering wherein particles keep a certain distance from each other, chain formation, and disc formation. These behaviors are explained by numerical simulation data (COMSOL Multiphysics v3.5a). After studying fluid motion under AC electrohydrodynamic condition, microelectrodes, the key elements to generate ETE, was integrated into microfluidic immune-biosensor using microfabrication technique. Microfluidic channels serve as solid phase in immunoassay, that were fabricated on inexpensive poly methylmethacrylate (PMMA) sheets by a solvent-based polymer imprinting and binding method. The microfluidic biosensors take advantage of quantum dots (QDs) as fluorescence probes. A low cost UV-LED was used as an excitation source, and data were collected by a CCD camera. Electrothermal effect increases the possibility of antibody-antigen binding by actively transporting analyte to the sensing part. With the enhancement of ETE, the time spent on the core part of immunoassay has been significantly reduced from 3.5 hours to 30 minutes.
Description: Thesis (M.S., Biomedical engineering)--Drexel University, 2011.
URI: http://hdl.handle.net/1860/3919
Appears in Collections:Drexel Theses and Dissertations

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