MATERIALS AND METHODS: A custom microfluidic platform was developed to generate a linear WSS gradient from 16 to 130 Pa. Microchannels were patterned with reverse cones and hemispheres in small (1-3 µm) and large (3-9 µm) sizes using two-photon polymerization and nanoimprinting. Human blood was perfused through the microchannels, and platelet deposition was quantified over time as the area coverage ratio (Aₚₗₜ/Aₜₒₜ) and area under the curve (AUC). Platelet detachment events were counted as an indicator of thrombus stability, and computational simulations supported the interpretation of local shear conditions.
RESULTS: Consistent trends emerged, although no statistical differences were observed relative to flat controls. Aₚₗₜ/Aₜₒₜ increased with WSS for all surfaces. At 16 Pa, small and large cones reduced platelet adhesion by approximately 84 and 98%, respectively, compared to flat controls. At 49 Pa, the reduction was about 95% for small cones and 80% for large cones. Conical geometries also promoted platelet washout at higher WSS. Small hemispherical features showed more than 50% lower platelet adhesion than flat surfaces for WSS > 16 Pa, with limited thrombus growth.
CONCLUSION: Conical micropatterns may be most effective at limiting platelet adhesion at lower WSS, while small hemispheres may perform better at higher WSS. These trends suggest a surface-shear interaction that warrants further investigation for LVAD surface optimization.