| The field of microfluidics is capable of producing useful biological tools. Cell separation is one aspect of that larger biological tool, capable of isolating cells of interest from a complex background. This thesis describes two approaches for microfluidic cell separation, magnetic, and size-based. The first approach, magnetic separation, is achieved by selectively attaching magnetic beads to cells or cell populations, then altering their path using micro-fabricated ferromagnetic objects. This technique is primarily useful in selecting certain populations of cells that can be differentiated by the chemicals on their surfaces. This thesis describes the first demonstration of this type of microfluidic cell separation.; The second method, size-based cell separation, is achieved using a recently described method called deterministic lateral displacement, in which particles of different sizes follow one of two paths, through a micro-fabricated array of posts. This method can be used as a sort of continuously operable filter, separating large particles from small particles, or it can be used to measure the size of objects. This thesis describes numerous applications of the technique to the separation of blood components and the measurement of blood cells.; The two methods complement one another in that magnetic separation takes advantage of differences in surface chemical properties, while the size separation takes advantage of morphological properties. |
