Study On The Method Of Measuring The Mechanical Properties Of Red Blood Cells With Blood Injury In Artificial Heart Based On Dielectrophoresis And Biological Microimage Analysis

Heart failure is one of the main causes of death in patients with cardiovascular diseases.For patients with severe heart failure,the effect of drug therapy is limited,and heart transplantation is limited by donor sources.Artificial heart has gradually become an important treatment method.Over the years,artificial heart technology has made great progress,but the blood damage caused by artificial heart is still an important problem,which seriously affects the life and quality of life of patients,and also hinders the wide application of artificial heart.At present,hemolysis injury modeling is mainly used to evaluate the degree of artificial heart injury to human body in the research of artificial heart blood injury.These studies can neither accurately explain the mechanism of artificial heart blood damage nor deeply study the process of artificial heart blood damage from the microscopic point of view.Therefore,in view of the limitations of artificial heart hemolytic injury research and the particularity of red blood cell image analysis,this thesis proposes a new idea of blood injury research:A method for measuring the mechanical properties of red blood cells based on dielectrophoresis and biological microimage analysis was established.Theoretical modeling and experimental research were combined to explore the mechanism of subhemolysis injury of artificial heart,expecting to provide support for theoretical in-depth and technical realization of artificial heart related research.The main research contents and innovations of this thesis are as follows:Firstly,the mechanical properties of red blood cells damaged by artificial heart blood were modeled,and the damage of RBC membrane structure,decrease of RBC mechanical stability,and increase of RBC hardness were deeply analyzed under the non-physiological shear stress of artificial heart,and the process of mechanical properties change of RBC under the shear stress was theoretically explained.Second,the formation principle and influencing factors of Dielectrophoresis(DEP)were analyzed,DEP force was calculated and modeled,a series of DEP microfluidic chips such as cell multi-angle stretching and trapezoidal parallel electrode were designed,and the feasibility of the measurement of mechanical properties of red blood cells based on dielectric electrophoresis was verified by numerical simulation and experimental study.Thirdly,aiming at the problems such as small difference between red blood cells and background,easy adhesion and overlap,and difficult edge recognition in the red blood cell microimage,the research on the mechanical property detection method of red blood cells based on microimage is carried out,and the deep learning technology is used to quickly and accurately identify and extract the mechanical properties of red blood cells,so as to lay a foundation for the research and interpretation of the mechanism of artificial heart subhemolytic damage.Finally,a series of cardiopulmonary bypass experiments were performed on the artificial heart,and the experimental study of measuring the mechanical properties of red blood cells for subhemolytic injury of the artificial heart was carried out based on DEP and micro fluidic technology.The red blood cell strain,Young’s modulus and shear modulus at 6 hours after CPB test were significantly different from those at 0 hours,indicating that the elasticity of red blood cells decreased with the increase of CPB test time,and the deforming ability of red blood cells decreased with the increase of CPB test time.These results further demonstrate the cumulative sclerosing effect of erythrocytes under the non-physiological shear stress of artificial heart circulation.The experimental results show that:The red blood cells of the shear modulus increases with the increase of shear stress,and then achieve the same saturation range(G=39.9～41.9 Pa),the result confirmed that the shear modulus of red blood cell skeleton network is largely affected by the external load hypothesis.Under the action of extremely high non-physiological shear stress,the spectrin network was overstretched and broke after exceeding the maximum shear modulus,resulting in irreversible deformation of RBC and subhemolysis injury.The experimental results not only proved the feasibility of using the mechanical properties of red blood cells to study the hemolysis of artificial heart,but also verified the effectiveness of the proposed model of mechanical properties of red blood cells damaged by artificial heart.The measurement and analysis of mechanical properties of erythrocyte stretching process in artificial heart can comprehensively evaluate the damage of erythrocyte subhemolysis caused by non-physiological shear stress of artificial heart.The innovations of this thesis include:designing a series of novel microfluidic chips for cell mechanical properties measurement integrated with DEP technology,which can measure cell mechanical properties with low cost,high throughput and no damage;The red blood cells were measured by dielectrophoresis,and the image information of red blood cells was automatically extracted efficiently and accurately by deep learning target detection technology;The mechanical properties of artificial heart hemolytic RBC were modeled to explain the process and mechanism of hemolytic RBC injury.The mechanical properties of RBC can be used as an important index to measure hemolytic RBC injury.The proposed method of measuring the mechanical properties of red blood cells of artificial heart based on dielectrophoresis and biological microimage analysis and the experimental study and mechanism explanation can lay a certain theoretical basis and technical support for the development of artificial heart.