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UBC Theses and Dissertations

Development of digital microfluidic device for dielectrophoretic manipulation of particles Chowdhury, Ovee Zaman


This thesis presents the development of a parallel plate lab-on-a-chip (LOC) device for manipulating biological/surrogate particles in droplet based digital microfluidic (DMF) platforms. A fundamental principle, known as dielectrophoresis (DEP), is used to manipulate the particles in a non-uniform electric field based on their polarizability. DEP can be observed as positive (pDEP) and negative (nDEP), moving particles toward the high and low intensity electric fields, respectively. Binary separation of two particles (Polystyrene beads and E.coli) has been shown on DMF platform by combining pDEP and nDEP. Polystyrene beads are trapped along the edge due to pDEP whereas cultured E.coli is repelled away from the edges due to nDEP. Although capturing the particles using pDEP is easier, for most biological applications requiring a high conductivity buffer medium, nDEP traps must be used to preserve the physiological characteristics of the particle. This thesis also contains the study of developing nDEP traps on DMF devices. The relation between the nDEP traps and the particle size has been demonstrated based on experimental results. Characterization of these traps of two different shapes (circular and squared) results in defining lifting and trapping zones. This study also yields in optimizing the trap size for single particle immobilization which is important for cell printing and growth applications. The ratio of trapping zone to the total area has been presented with a limiting factor K, which is proposed as a parameter to define the maximum trapping zone. Design of experiment has been used as an additional tool to show the relationship between the trapping zone and the total trap.

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Attribution-NonCommercial-NoDerivatives 4.0 International