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Developing a Lob-On-a-Chip platform for manipulation and separation of microparticles

University of British Columbia

Cell/particle separation has a wide range of applications in environmental monitoring (e.g., air/water purification), food industry (e.g., microfiltration for improving food quality), oil and gas (e.g., particle separation in cyclones), and medicine/biotechnology (e.g., isolation of circulating tumor cells). Conventional procedures for separation purposes require costly infrastructure and several operational steps which are time-consuming and associated with human error. In the past two decades, there has been a tendency to develop microfluidic techniques, so-called lab-on-a-chip (LOC), to miniaturize and automate these procedures. Differences in the physical, electrical and biological properties of target cells/particles from the other components present in the fluid samples are crucial in the development of such microfluidic-based separation techniques. One of these techniques, which uses dielectrophoresis (DEP) force, is capable of the electric-based manipulation of noncharged particles in a non-uniform electric. Despite the general success, DEP still has not reached its full potential for high throughput operations. This thesis aims at studying the effect of several parameters on the performance of DEP-based microfluidic devices. In essence, prior to the separation process, particles need to be focused in a narrow region. A common approach is sheath-assisted focusing, which is numerically studied in this thesis to report the effective factors on the focusing width. COMSOL Multiphysics modeling is used to find the effect of the geometry of the electrodes (width and spacing) on the resulting DEP force. The effect of the applied voltage, channel height on the DEP-based manipulation of particles is investigated and it is shown that higher voltages and lower channel heights lead to more effective DEP manipulation. Furthermore, the effect of the length and width of the channel, the deflection angle of the electrodes, the volumetric throughput, and the particle size on the DEP-induced displacement of particles is studied and used to develop a model to predict the displacement. The applicability of these findings is shown by testing the platform with NIH 3T3 mouse fibroblast cells. Finally, the developed device is used for sheath-assisted and sheathless separation of three sizes of particles, and the throughput, as well as the separation efficiency of each design, is reported.

Text

2020-12-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/76870

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/