Microfluidic flow assay and quantification of platelet accumulation.

<p>A. Schematic of the microfluidic flow assay. Four channels (h = 50 µm, w = 500 µm) were placed over a patch of type 1 collagen. Blood was pipetted in an inlet well (large circle) and withdrawn through the outlet (small circle) at a constant flow rate to achieve the desired wall shear rate. Platelet accumulation was monitored at the upstream edge of the collagen patch by epifluorescence microscopy. B. Platelet surface coverage was measured over the course of 5 min at 150 s⁻¹ (○), 300 s⁻¹ (□), 750 s⁻¹ (⋄) and 1500 s⁻¹ (+). In addition to the final platelet surface coverage (SC), the lag time (Lag_T, black line) and the accumulation velocity (V_PLT, red dotted line) were calculated from each curve. Lag time was defined as the time to 1% surface coverage. Accumulation velocity was defined as the slope of line SC versus time from t_LAG to 5 min.