Fig. 1

Platelet [Ca²⁺]_c activation is dependent on free-flow trajectory and occurs at initial flow acceleration at stenosis entry. A, B Color maps showing velocity (U m s⁻¹) and strain rate (\(\dot{\gamma}\) s⁻¹) distributions within an x,y plane 50 μm from the microchannel floor (derived from CFD modelling of blood flow; Q = 200 μL/min) at a prototypical stenosis with θ_e = 80°. White lines on the strain rate map show T1-, T4-, and T14-predicted platelet trajectories (2 μm particles) (see Methods). C Representative trajectory-dependent platelet [Ca²⁺]_c profiles for trajectories T1, T4, and T14 (B). D CFD-derived velocity profiles for T1, T4, and T14. E CFD-derived strain rate profiles for T1, T4, and T14. F CFD-derived shear stress profiles for T1, T4, and T14. G Coordinate system showing trajectories T1, T4, and T14 and 10 μm Ø subsampling regions of interest as a function of position within the microfluidic. H Ca²⁺ sampling along T1, T4, and T14 for 10 μm Ø ROIs defined as Baseline—− 3 mm upstream of stenosis apex center-point; Acc1—at start of flow acceleration zone; Acc2—mid-acceleration zone; Acc3—end of flow acceleration zone; Apex—center-point of stenosis apex; Vortex—average [Ca²⁺]_c at center of predicted vortex zone for T14 only; Post-apex—3 mm downstream of stenosis apex center-point (N = 20 independent experiments)