Morphology and time evolution of aggregates at the rear of pillars. (a–c) SRBCs from sample 4: pictures of aggregate formation at the rear of a pillar. For t = 10 min, only a few cells are in adhesion on the PDMS pillar. After 30 min, an aggregate has grown on both corners at the rear of the pillar. After 60 min, the two aggregates merge and the length remains stable. Scale bars, 20 μm. (d–f) Healthy RBCs deposition on pillars (sample 10). Only a few cells stick to the pillar. Scale bars, 20 μm. (g) Temporal evolution of the length of SRBCs aggregate at the rear of pillars (sample 4, red circle; sample 8, orange triangle; sample 9, green square; 25% hematocrit). The aggregate length is defined as the maximum extent from the base of the pillar and the fluctuating end. For t < 15 min, only a few cells are in adhesion on the PDMS pillar. Then the growth initiates and aggregates can reach a size of ∼40 μm. For each curve, the length is averaged over seven different aggregates. Control experiment, with healthy RBCs: only few of them stick to the PDMS pillar (blue diamonds, sample 10, 25% hematocrit). To see this figure in color, go online.