Sheathless inertial cell ordering for extreme throughput flow cytometry

Abstract

Rapid and accurate differentiation of cell types within a heterogeneous solution is a challenging but important task for various applications in biological research and medicine. Flow cytometry is the gold standard in cell analysis and is regularly used for blood analysis (i.e., complete blood counts). Flow cytometry, however, lacks sufficient throughput to analyze rare cells in blood or other dilute solutions in a reasonable time period because it is an inherently serial process. In this study, we exploit inertial effects for label- and sheath-free parallel flow cytometry with extreme throughput. We demonstrate a microfluidic device that consists of 256 high-aspect (W = 16 microm, H = 37 microm) parallel channels yielding a sample rate up to 1 million cells s(-1), only limited by the field-of-view of our high-speed optical interrogation method. The particles or cells flowing through the channels are focused to one uniform z-position (SD = +/-1.81 microm) with uniform downstream velocity (U(ave) = 0.208 +/- 0.004 m s(-1)) to reduce the probability of overlap and out-of-focus blur and provide similar cell signature images for accurate detection and analysis. To demonstrate a proof-of-concept application of our system operating at these throughputs, we conducted automated RBC and leukocyte counts on diluted whole blood and achieved high counting sensitivity and specificity (86-97%) compared to visual inspection of raw images. As no additional external forces are required to create ordered streams of cells, this approach has the potential for future applications in cost-effective hematology or rare-cell analysis platforms with extreme throughput capabilities when integrated with suitable large field-of view imaging or interrogation methods.

Engineering fluid flow using sequenced microstructures

“…5b), which are both useful operations to prepare cellular samples for downstream analysis. In these applications we also simultaneously make use of inertial focusing of particle streams that is dependent on particle size 11,16,21 . In this case while 10 mm particles maintain their preferred inertial focusing position due to larger inertial lift forces, smaller 1 mm particles or dye molecules, which experience two orders of magnitude weaker inertial lift forces, follow the flow streamlines away from the channel centre.…”

Cell phones go cellular—Current scale‐down lab‐in‐your‐pocket applications

“…Sheath flow that supports hydrodynamic focusing is possible in optofluidic designs but perhaps the most promising solution is the massive parallelization of the interrogation channel. The insertion at the sample inlet of a 256 parallel straight channel ''filter'' was shown to produce the ordered flow of cells in an equal amount of parallel tracks (14). Large field-of-view imaging solutions like afforded by the lensless approaches can then be used to interrogate cells flowing at rates up to a million cells per second.…”

Self-organizing microfluidic crystals

“…Moreover, they can be harnessed for microuidic and lab-on-a-chip applications. Orderly ow eases recognition and interrogation of suspended objects in cytometry 7 and bioassays. 8 Flowing crystals could be used as dynamically programmable metamaterials, assembled with high throughput in continuously operating microdevices, or as tunable diffraction gratings.…”