Design And Experimental Research Of Piezoelectric Pumps With Flexible Valves

In recent years,with the rapid development of tissue engineering and precision processing,organ-on-a-chip,with microfluidic chip technology as the core,is becoming a highly distinctive emerging field in biomedicine.To simulate the actual physiological environment in the body,micropumps are used to supply nutrients to the cells and discharge waste during dynamic culture.This process requires a simple and easy-to-integrate micropump without damaging cells.The micropump driven by piezoelectricity has simple structure,rapid reaction and high energy density.However,existing piezoelectric pumps with valves have a high operating frequency,and valves are mostly made of hard materials.The hard valve is easy to damage the living cells flowing through the valve,and it is difficult to transport the living cell culture fluid.These limitations restrict its potential in application of organ-on-a-chip.Based on the working principle of the heart aortic valve and venous valve,piezoelectric pumps with flexible valves have been proposed in this paper to transport living cell culture fluid.The electro-solid-fluid coupling models of the piezoelectric pumps with flexible valves are presented based on the moving mesh.The vibration characteristics of piezoelectric vibrator,the dynamic characteristics of the flexible three-leaflet valve and the transient flow characteristics of the internal flow field are analyzed.Finally,the working characteristics and applications of the piezoelectric pumps with flexible valves are systematically analyzed through the cut-off performance test of the flexible valves,the output performance of the piezoelectric pumps,the viscous medium transfer and cell culture fluid delivery.The above work provides a design reference for living cells delivery and expands the application of piezoelectric pump.The main studies are as follows.1.The background and significance of the research in this paper are described,and the current development of piezoelectric pumps with valves is reviewed.The applicability and limitations of various integrated valves in piezoelectric pumps are summarized,and the problems that still need further research are presented.2.In response to the limitations of existing piezoelectric pumps for cell culture fluid delivery,piezoelectric pumps with flexible valves are proposed,which have enriched the structure types of piezoelectric pumps.A simplified dynamic model of piezoelectric pumps with flexible valves are established,and the relationship between the parameters of the flexible valve and the output performance of the piezoelectric pump is elucidated.3.The finite element model of the piezo-pump with flexible three-leaflet valve is established based on the electro-solid-liquid multi-physical field simulation with moving mesh,and the vibration characteristics of piezoelectric vibrator,the dynamic characteristics of the flexible threevalve and the transient flow characteristics of the internal flow field are systematically analyzed.Meanwhile,a series of tests show that the miniaturized piezoelectric pump with flexible two-leaflet valve has a higher flow rate and a wider range of working frequencies.This result proves the effectiveness of the miniaturized design of the piezoelectric pump with flexible valve.4.The structure of a flexible three-valve piezoelectric pump has been miniaturized.The vibration characteristics of the piezoelectric vibrator,the dynamic characteristics of the flexible two-leaflet valve and the transient flow characteristics of the internal flow field are analyzed using multi-physics field simulations.The effectiveness of the miniaturized design of piezoelectric pump with flexible valve is verified by comparing the valve performance test,pump output performance test and viscosity medium delivery test.5.Yeast cell culture fluid has been transported by the piezoelectric pump with flexible valve.By comparing the cell survival rate before and after transfer,it is shown that the piezoelectric pump with flexible valve maintained a high cell survival rate when transferring yeast cell culture solution.Meanwhile,the performance and application effect of the piezoelectric pump for cell culture fluid delivery are verified.The application field of the piezoelectric pump is also expanded.