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Electrohydrodynamic focusing and light propagation in 2-dimensional microfluidic devices for preconcentration of low abundance bioanalytes

Piasecki, Tomasz (2012) Electrohydrodynamic focusing and light propagation in 2-dimensional microfluidic devices for preconcentration of low abundance bioanalytes. PhD thesis, Dublin City University.

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This thesis presents work on electrohydrodynamic focusing (EHDF) and photon transmission to aid the development of species preconcentration and identification. EHDF is an equilibrium focusing method, where a target ion becomes stationary under the influence of a hydrodynamic force opposed by an electromigration force. To achieve this one force must have a non-zero gradient. In this research a novel approach of using a 2-dimensional planar microfluidic device is presented with an open 2D-plane space instead of conventional microchannel system. Such devices can allow pre-concentration of large volume of species and are relatively simple to fabricate. Fluid flow in these systems is often very complex making computer modelling a very useful tool. In this research, results of newly developed simulations using COMSOL Multiphysics® 3.5a are presented. Results from these models were compared to experimental results to validate the determined flow geometries and regions of increased concentration. The developed numerical microfluidic models were compared with previously published experiments and presented high correspondence of the results. Based on these simulations a novel chip shapes were investigated to provide optimal conditions for EHDF. The experimental results using fabricated chip exceeded performance of the model. A novel mode, named lateral EHDF, when test substance was focused perpendicularly to the applied voltage was observed in the fabricated microfluidic chip. As detection and visualisation is a critical aspect of such species preconcentration and identification systems. Numerical models and experimental validation of light propagation and light intensity distribution in 2D microfluidic systems was examined. The developed numerical mode of light propagation was used to calculate the actual light path through the system and the light intensity distribution. The model was successfully verified experimentally in both aspects, giving results that are interesting for the optimisation of photopolymerisation as well as for the optical detection systems employing capillaries.

Item Type:Thesis (PhD)
Date of Award:March 2012
Additional Information:Brett Paull and Mirek Macka (External Supervisors UTAS, Hobart, Australia)
Supervisor(s):Brabazon, Dermot
Subjects:Physical Sciences > Analytical chemistry
Engineering > Materials
Engineering > Mechanical engineering
Physical Sciences > Physics
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Engineering and Computing > School of Mechanical and Manufacturing Engineering
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
Funders:Science Foundation Ireland, Mechanical and Manufacturing Engineering, DCU
ID Code:16698
Deposited On:05 Apr 2012 11:28 by Dermot Brabazon. Last Modified 05 Apr 2012 11:28

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