SEPARATION OF CELLS AND CELL-SIZED PARTICLES BY CONTINUOUS SPLITT FRACTIONATION USING HYDRODYNAMIC LIFT FORCES

The use of hydrodynamic lift forces for the separation of particles ac cording to size by continuous SPLITT fractionation is explored. The me chanism for particle separation in the transport mode of SPLITT fracti onation is first explained. This is followed by a discussion of the hy drodynamic lift forces that act upon particles entrained in fluid flow between the parallel bounding walls of the SPLITT cell. The effect of the bounding walls on particle motion both parallel and perpendicular to the direction of flow is explained. Computer simulations of partic le trajectories are presented that predict extremely high size selecti vity for the method. A parallel experimental study was carried out usi ng both polystyrene latex particles and red blood cells. The experimen tal selectivity was found to be smaller than that predicted theoretica lly. This discrepancy is attributable to nonidealities in the construc tion of the SPLITT cell. Nonetheless, the results are promising. Suspe nsions of polystyrene particle standards (from 2 to 50 mum in diameter ) demonstrate that fast and relatively clean size separations are poss ible provided particles differ sufficiently in size and flow condition s are properly optimized. It is also shown that the system has the pot ential to quickly and gently separate blood cells from plasma.