Design And Experimental Research Of Piezoelectric Micropump System Based On Insulin Precision Infusion

In recent years,piezoelectric micropump,as a kind of pumping unit different from traditional ones,has the advantages of simple structure,anti-electromagnetic interference,low cost,and easy integration.Therefore,it is gradually becoming a research hotspot for researchers at home and abroad.Specifically,the small size and high precision characteristics of the piezoelectric micropump can be used for the accurate infusion of drugs,such as insulin infusion,which can more accurately adjust the dosage,speed and target of the infusion.However,in the current research on the piezoelectric micropump system based on insulin precision infusion,the driving voltage of the micropump is high or it is not easy to integrate,and its infusion precision and accuracy need to be further improved.In addition,the precise insulin infusion control of piezoelectric micropump system remains to be studied.This work is supported by the National High-tech Research and Development Program(863 Program)project‘Blood Glucose Monitoring and insulin injection Microsystem’(project number:2011AA040406)and the horizontal project‘Piezoelectric precision infusion micropump prototype and its control technology Development’(project number:2020DQ0184).The aim is to develop a low cost,small volume,low voltage and high performance insulin precision infusion system.The key technologies of design,optimization,drive control,insulin infusion system integration and performance experiment of piezoelectric micropump were studied.In this paper,a double-valve piezoelectric micropump(hereinafter referred to as"piezoelectric micropump")structure suitable for insulin infusion was proposed,which can provide high precision and accuracy of insulin infusion under small volume and low voltage conditions.The precision infusion control of the integrated system was realized.The main research contents are as follows:(1)Aiming at the small volume and high output performance of the piezoelectric micropump,the piezoelectric vibrator with small diameter,thin shape and high performance parameters was selected as the driving source of the micropump.The piezoelectric vibrator is driven by square wave signal with high and low level conversion speed and high energy density.The theoretical analysis,simulation,and experimental test explore the working characteristics of the selected piezoelectric vibrator,which lays a foundation for the subsequent design,manufacture,and test.In addition,the cantilever valve was analyzed from multiple angles,including dynamic and natural frequency analysis based on van der Waals forces.The structure of multi-plate cantilever valve was proposed.The experimental results show that the multi-plate cantilever valve has strong rectification performance,especially the working efficiency is improved compared with the traditional type.It is beneficial to improve the output performance of piezoelectric micropump.(2)The working principle and characteristics of the proposed piezoelectric micropump were analyzed.The simplified working model of the micropump was presented,and the working characteristics and important influencing factors were defined.The characteristics of the local flow field of the micropump were defined by theoretical analysis and simulation.The feasibility of the proposed ramp flow channel for reducing fluid resistance and improving the comprehensive output performance of the micropump by using fluid inertia combined with the action of multi-valve plate cantilever valve was illustrated by comparison.The fluid-structure coupling analysis of the whole micropump was carried out to simulate its working condition.The working process of the micropump was analyzed through the distribution of internal flow line and velocity field,and its overall working characteristics were defined.(3)Piezoelectric micropump prototypes were developed.According to the experimental test results,the effects of pump structure(chamber height,inlet and outlet diameter,and diversion groove depth)size,valve and diaphragm stiffness on the output performance of the micropump were explored,and the micropump structure was optimized.The output performance of the optimized micropump prototype was tested,including self-priming,frequency,voltage,and pressure-flow characteristics.The fluid delivery capability of the proposed micropump under small volume and low voltage was investigated.The experimental test results show that the output flow rate and pressure of the micropump under the conditions of 36V and 230Hz are 3ml/min and23k Pa,respectively.Further,its output performance at 60V,230Hz reaches 4.8ml/min and 40k Pa,and its volume is only 12×12×3mm~3.(4)A special driving power supply for piezoelectric micropump was developed,which includes two parts:control module and drive module.According to the function characteristics of CA51F003N2 chip,the precise control of insulin infusion by piezoelectric micropump was realized.Furthermore,a variety of control forms were set up for the drive module.The output power of micropump and drive power system was tested by theoretical and experimental means.The efficiency and power advantages of the drive board and micropump system were identified.The portable power supply was provided for the subsequent application research of piezoelectric micropump system based on insulin precision infusion.According to the test results,when the mechanical efficiency of the micropump reaches 86.25%,the system power is only 20mw.(5)The piezoelectric micropump,embedded soft needle and special drive power were integrated into the insulin precision infusion system to explore the function and effect of piezoelectric micropump system in the precision,speed and convenience of insulin precision infusion.First of all,the interaction between the embedded needle and human skin(soft tissue)involves a complex mechanical state.The main mechanical properties of needle body when inserted into soft tissue were analyzed theoretically,and the analytical expressions of nonlinear displacement and related strain were derived.Subsequently,analysis and experimental studies were conducted using the integrated insulin precision infusion system,including evaluation of the system’s infusion capacity and simulation of basal rate and premeal high-dose infusion.The experimental results show that the flow resolution of the micropump system reached 0.15μl,that is,the minimum resolution of the system’s insulin infusion is 0.01U～0.02U,and the infusion deviation fluctuates only about±3%.To sum up,this paper realizes the high performance output of piezoelectric micropump under the condition of small volume and low voltage through technical means.The micropump system can satisfy the medical requirement of precision insulin infusion.The system has better flow resolution and infusion accuracy.In this paper,the theory and experiment of piezoelectric micropump system for insulin precision infusion were studied,and the application of micropump in the field of drug infusion was explored.At the same time,it provides a research basis for the design,analysis and application of this type of piezoelectric micropump system.In addition,it provides theoretical reference and experimental feasibility analysis for constructing continuous subcutaneous insulin infusion scheme based on piezoelectric micropump system(traditional form or patch insulin pump).