Dynamic wetting of human blood and plasma on various surfaces

Surface fouling from coagulated blood is a major challenge in medical industry. However, the wetting physics and dynamics of blood on surfaces are not well understood nor are the quantitative influences due to surface and fluid properties. The present study investigates the effect of surface wetting and dynamics resulting for human blood and plasma, namely hemophobicity, on surfaces with different wettability. To examine effects of fluid properties, the wetting characteristics for liquids with Ohnesorge number similar to that of blood and plasma are also considered. Among the tested surfaces, a superhydrophobic, non-fluorinated, nanocomposite coating based on an inexpensive spray application of a polymer/nanoparticle dispersion provided a very high degree of blood and plasma repellency. This was evidenced by advancing contact angles greater than 153° and roll-off angles less than 18°, for both fluids, and no evidence of a blood trail. However, air exposure during the contact angle measurements led to the formation of a thin gel-like protein skin on the surface (even though an anti-coagulant was added), which distorted the receding droplet curvature. This previously unreported feature did not modify the static contact angle but appears to have caused a significant increase in contact angle hysteresis.