| As an important means to save the increasing patients with heart disease,the development of blood pumps is experiencing a rapid increase.When blood contacts with the blood pump surface,blood coagulation and thrombosis may occur.In order to ensure the survival of the blood pump users,the mechanism of blood coagulation on the material surface has been investigated by researchers.Research show that blood coagulation is due to plasma protein adsorption to the surface of material,causing a series of subsequent platelet adhesion and aggregation,activation of coagulation system and fibrinolytic system,and ultimately the formation of thrombus.The previous researchers have done a large number of studies on the effect of different materials on protein adsorption and feature of blood coagulation under static conditions(no flow).However,in the actual application of blood pump,material and blood contact is under flow.This study focuses on the effect of flow near wall surface on protein adsorption.The study used viscous fluid boundary layer theory to analyze the flow of viscous sublayer.The thickness of viscous sublayer in blood pump was obtained and compared with three featured sizes of protein adsorption(the size of protein,the thickness of protein adsorption layer,and the force range of protein adsorption).Wall shear rate was then proposed as the similarityparameter of the flow near wall between the experiment and the prototype blood pump.Based on the numerical results of the flow in the blood pump,the distribution and main range of wall shear rate were obtained.According to the theory of classic tubular Hagen-Poiseuille flow,a micro tubular flow experimental system has been designed and built,which can realize the flow condition of the same wall shear rate range in blood pump.By measuring the pressure drop and flow rate of the experimental section,the velocity distribution and wall shear rate of the internal flow in the circular tube can be obtained.Stainless steel and medical polyurethane(PU)were chosen as the experimental materials of protein adsorption.In the protein adsorption experiment,40mg/mL bovine serum albumin(BSA)flew through the test tube under flow state of different wall shear rates(0~1.4×105 s-1)and static state.The amount of protein adsorption after flow was obtained by BCA method.Base on the experimental results,the difference of the protein adsorption on the material surface under the flow state and static state was analyzed.And the influence of different flow conditions near wall on the protein adsorption was discussed. |
