A near-superhydrophobic surface reduces hemolysis of blood flow in tubes

The use of an external mechanical pump to sustain the circulation in a body, also known as extracorporeal circulation, is an integral part of many medical procedures such as hemodialysis and cardio-pulmonary bypass. However, the damage to red blood cells caused by the flow-induced shear stresses in the flow circuit has remained an intractable problem for many years, limiting the operational duration of extracorporeal circulation. In this study, near-superhydrophobic surfaces were investigated as a potential solution to mitigate the hemolysis of blood during extracorporeal pumping through the use of a proof-of-concept flow circuit. It was found that the thin layer of air trapped by the near-superhydrophobic surface due to the Cassie-Baxter state reduced the wall shear stress exerted on the blood flow, resulting in a corresponding decrease in the rate of hemolysis. For blood that undergoes an oscillatory flow, this reduction in the hemolysis was shown to be directly related to the mean shear rate and shear rate amplitude of the flow. Near-superhydrophobic surfaces trap circulating blood in Cassie-Baxter state, thereby reducing the contact area available for shearing of erythrocytes to take place.