Development of continuous particle/cell manipulation and separation by optical force

Abstract

Separation of particles and biological particulates has many potential applications in the bio-chemical research field such as purification of sample, blood cell fractionation, separation of mammalian cells from normal cells and others. Due to its non-invasive nature, the optical force has been successfully used for bio-logical cell manipulation in various applications. Although several types of optical force platform has been developed and many studies for single and multiple particulates manipulation, purification and sorting pur-pose, there is some limit of throughput and non-continuous matter. This thesis presents theoretical modeling and experimental approaches of optical cell separation and practical applications of cross-type optical particle separator (COPS) for separation and manipulation of cells. First, in order to apply an cross-type optical particle separation method, a method for improving the microfluidic size separation technique known as pinched flow fractionation (PFF) has been demonstrated experimentally and analyzed by performing numerical calculations. This enhancement of separation is achieved by imposing a cross-type optical scattering force on the original PFF design. Three different polystyrene latexes (PSLs) with diameters of 2, 5, and 10 um were separated with PFF and optically enhanced PFF (OEPFF) devices. The separations achieved with the two devices were compared and enhancements in the separation distance by factors of up to approximately 15 were achieved. Theoretical calculations were also performed to interpret these results. Next developed and experimentally verified the double emulsion behavior in the cross-type optical particle separation as the simplest model of cell in the COPS. The behavior of double emulsions in a cross-type optical particle separation system was studied for different combinations of the refractive indices and different inner and outer layer radii. The radii and refractive indices of the double emulsio...