On-chip magnetophoretic isolation of CD4 + T cells from blood.

This paper presents the design, fabrication, and testing of a magnetophoretic bioseparation chip for the rapid isolation and concentration of CD4 + T cells from the peripheral blood. In a departure from conventional magnetic separation techniques, this microfluidic-based bioseperation device has several unique features, including locally engineered magnetic field gradients and a continuous flow with a buffer switching scheme to improve the performance of the separation process. Additionally, the chip is capable of processing significantly smaller sample volumes than conventional methods and sample losses are eliminated due to decreased handling. Furthermore, the possibility of sample-to-sample contamination is reduced with the disposable format. The overall dimensions of the device were 22 mm by 60 mm by 1 mm, approximately the size of a standard microscope slide. The results indicate a cell purity of greater than 95% at a sample flow rate of 50 ml/h and a cell recovery of 81% at a sample flow rate of 10 ml/h. The cell purity was found to increase with increasing the sample flow rate. However, the cell recovery decreases with an increase in the flow rate. A parametric study was also performed to investigate the effects of channel height, substrate thickness, magnetic bead size, and number of beads per cell on the cell separation performance.