Separation of Leukocytes from Blood Using Spiral Channel with Trapezoid Cross-Section

Abstract

Inertial microfluidics has recently drawn wide attention as an efficient, high-throughput microfluidic cell separation method. However, the achieved separation resolution and throughput, as well as the issues with cell dispersion due to cell-cell interaction, have appeared to be limiting factors in the application of the technique to real-world samples such as blood and other biological fluids. In this paper, we present a novel design of a spiral inertial microfluidic (trapezoidal cross-section) sorter with enhanced separation resolution and demonstrate its ability in separating/recovering polymorphonuclear leukocytes (PMNs) and mononuclear leukocytes (MNLs) from diluted human blood (1-2% hematocrit) with high efficiency (>80%). PMNs enriched by our method also showed negligible activation as compared to original input sample, while the conventional red blood cell (RBC) lysis method clearly induced artificial activation of the sensitive PMNs. Therefore, our proposed technique would be a promising alternative to enrich/separate sensitive blood cells for therapeutic or diagnostic applications.

Continuous separation of blood cells in spiral microfluidic devices

“…8. This translates to a throughput of $3.6 ll/min of whole blood (45% hct) which is comparable to the recent blood sorting work by Han et al 43 where they showed >90% efficiency of enrichment of WBCs. Although platelets could not be separated, there is an almost complete separation of leukocytes and erythrocytes.…”

“…Further, since the throughput and efficiency was calculated using only the viable cells collected at the outlets, the throughput is indicative of cell viability. As such blood cells are quite robust as shown in the previous work by Toner et al 1 and Han et al 43 …”

“…Sun et al 41 showed sorting of spiked HeLa cells and 20Â diluted blood cells in a double/fermat spiral with a $90% efficiency, but only $80% recovery rate of sorted HeLa cells. Spiral channels with trapezoidal cross section have also been used by Han et al 43 for >90% WBCs enrichment, but the trapezoidal cross-section has complicated fabrication process which requires that the master for PDMS (polydimethylsiloxane) casting be milled rather than patterned on a wafer.…”

Particle Focusing in Curved Microfluidic Channels

“…These forces allow for the precise alignment of particles in a flow at throughputs orders of magnitudes higher than in previous microfluidic technologies. The high throughput nature of inertial focusing has enabled a range of microfluidic technologies for biomedical applications from separation technologies [8][9][10][11][12] , to automated sample preparations 13,14 , to novel cell analysis techniques such as cell deformability cytometry 15 and the isolation of circulating tumor cells from blood 16,17 .It is generally accepted that inertial focusing in straight channels is dependent on two main parameters: Reynolds number, defined as Re C 5 rU Max D h /m, where r is the fluid density, m is the fluid viscosity, U Max > 3/2U Avg is the maximum velocity of the fluid and D h is the hydraulic diameter of the channel defined as D h 5 2hw/(h 1 w) where h and w are the height and width of the channel cross section respectively, and the particle confinement ratio, l 5 a/D h , where a, is the particle size. Prior research has determined a minimum threshold for inertial focusing to occur such that l .…”

“…These forces allow for the precise alignment of particles in a flow at throughputs orders of magnitudes higher than in previous microfluidic technologies. The high throughput nature of inertial focusing has enabled a range of microfluidic technologies for biomedical applications from separation technologies [8][9][10][11][12] , to automated sample preparations 13,14 , to novel cell analysis techniques such as cell deformability cytometry 15 and the isolation of circulating tumor cells from blood 16,17 .…”