Date of Award

5-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Bioengineering

Committee Member

Dr. Guigen Zhang, Committee Chair

Committee Member

Dr. Bruce Gao

Committee Member

Dr. Rodrigo Martinez-Duarte

Committee Member

Dr. Xiangchun Xuan

Abstract

Dielectrophoresis (DEP) has been a subject of active research in the past decades and has shown promising applications in Lab-on-Chip devices. Currently researchers use the point dipole method to predict the movement of particles under DEP and guide their experimental designs. For studying the interaction between particles, the Maxwell Stress Tensor (MST) method has been widely used and treated as providing the most robust and accurate solution. By examining the derivation processes, it became clear that both methods have inherent limitations and will yield incorrect results in certain occasions. To overcome these limitations and advance the theory of DEP, a new numerical approach based on volumetric-integration has been established. The new method has been proved to be valid in quantifying the DEP forces with both homogeneous and non-homogeneous particles as well as particle-particle interaction through comparison with the other two methods. Based on the new method, a new model characterizing the structure of electric double layer (EDL) was developed to explain the crossover behavior of nanoparticles in medium. For bioengineering applications, this new method has been further expanded to construct a complete cell model. The cell model not only captures the common crossover behavior exhibited by cells, it also explains why cells would initiate self-rotation under DEP, a phenomenon we first observed in our experiments. To take a step further, the new method has also been applied to investigate the interaction between multiple particles. In particular, this new method has been proved to be powerful in elucidating the underlying mechanism of the tumbling motion of pearl chains in a flow condition as we observed in our experiments. Moreover, it also helps shed some new insight into the formation of different alignments and configurations of ellipsoidal particles. Finally, with the consideration of the Faradic current from water electrolysis and effect of pH, a new model has been developed to explain the causes for the intriguing flow reversal phenomenon commonly observed (but not at all understood) in AC-electroosmosis (ACEO) with reasonable outcomes.

Share

COinS