Red Blood Cell Partitioning Using a Microfluidic Channel with Ladder Structure

Figures

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  Figure 1. Geometries of microfluidic channels with the ladder structure used in the study, in which the flow directions at the inlet and outlet are reversed. The letter “P” denotes the parent channel, while “B1” to “B6” denote bifurcating channels 1 to 6. Five types of microfluidic channels were prepared by varying the parent channel width (WP), the distance between branches (LD) and the length of the bifurcating channels (LB). The bifurcating channel width (WB) was fixed in all cases. When comparing the parent channel widths, three different WP values of 10, 13, and 16 µm were prepared, corresponding to Case 1, Case 2, and Case 3, respectively. When LD varied, WP and WB were fixed at 10 µm, and LD was varied to 90 µm, and 150 µm, respectively, designated as Case 4, and Case 5. Image analysis was conducted by considering the region of interest (ROI) indicated by the red dashed frames. NP and Ni denote the number of RBCs within the ROI. Fi denotes the number of RBCs passing through the bifurcating channel Bi.

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  Figure 2. Theoretical fractional flow ratios into each bifurcating channel of the ladder structure model for five different cases.

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  Figure 3. (a) Comparison of normalized hematocrit values and (b) fractional RBC flux for each bifurcating channel at three different parent channel widths.

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  Figure 4. (a) Location of the measured cross-sections (C1–C1′ and C2–C2′). The cross-section C1–C1′ is located at the parent channel, and the cross-section C2–C2′ is located between the bifurcating channel B1 and B2. (b) Comparison of the RBC distributions at the channel cross-section C1–C1′ for different parent channel widths. (c) Comparison of the RBC distributions at the channel cross-section C2–C2′ for different parent channel widths.

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  Figure 5. (a) Comparison of the normalized hematocrit values and (b) fractional RBC flux for each bifurcating channel at three different distances between branches.

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  Figure 6. (a) Location of the measured cross-section (C3–C3′). The cross-section C3–C3 is located immediately before the bifurcating channel B2 (b) Comparison of the RBC distribution at channel cross-section C3–C3′ for different distances between branches.

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  Figure 7. (a) Normalized hematocrit values and (b) fractional RBC fluxes for each bifurcating channel at parent channel tube hematocrits of 10% and 25%. Here, the channel geometry corresponds to Case 1.