Date of Graduation

5-2008

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor

Hestekin, Christa N.

Abstract

Current research in mircofluidic technology is underway to develop automatic micro-analyzing chips for medical diagnostic testing. Diagnostic testing often requires separation of specific biological particles from a sample, and many of these molecules contain electric or magnetic properties. This project investigates the potential for separation in electromagnetophoretic and magnetophoretic microfluidic technology. In electromagnetophoresis, the Lorentz force acting on a current carrying medium in a homogeneous magnetic field creates a pressure gradient in the fluid, resulting in an applied force to particles present in the separation medium. This force causes the particle to have a velocity component that is perpendicular to the medium flow and results in absorption to the capillary wall. Since the force required for absorption is size-dependent, particles can be separated based on size and electrical properties. In magnetophoresis, magnetic particles are separated by the application of an inhomogeneous magnetic field. Previous research by Watarai et. al. shows that polystyrene particles and red blood cells in a paramagnetic medium could be trapped in a silica capillary by the application of an inhomogeneous magnetic field to pressure-driven flow.9 Fused silica, a widespread material used in mircofluidics, is an amorphous polymer made from silica dioxide (SiO2) and silanol (SiOH) monomers. When exposed to a buffer solution, OH- ions ionize SiOH to SiO-, resulting in a negative capillary surface charge. The negatively charged capillary wall attracts cations present in the buffer solution, forming the electric double layer (EDL). When exposed to an external electric field, the cations in the EDL migrate towards the cathode, causing a bulk fluid motion. The resulting bulk flow can serve as a pump in microfluidic technology. In this project, EOF measurements were performed to explore its potential use in magnetophoretic technology.

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