Design And Experimental Study Of Magnetic Driven Micropump

Micropump is an important part of microfluidic system.Its main function is to transfer liquid flow and distribute liquid flow.It is widely used in micro sensors,microbiology,chemical analysis and various kinds of microfluidic transportation.Magnetic driven micropump is a kind of micropumps.The electromagnetic driven micropump and ferrofluidic driven micropump are all magnetic driven micropumps.The magnetic force drives magnets as driving force.The electromagnetic field of electromagnetic driven micropump is derived from the electromagnet.The principle of electromagnetic driving micropump is simple,but its technology is complex,the cost is high and the volume is large.The magnetic field of ferrofluidic driven micropump is derived from permanent magnet material,and magnetic force is produced by ferrofluid which is magnetized by permanent magnet material.The motion control of ferrofluid driven micropump is flexible and the pumping process is simple,but its pumping flow is not high and its structure is complex.In recent years,the research of magnetic drive micropump mainly focuses on the design and optimization of its structure and reducing the difficulty of the manufacturing process.In the first chapter,the micropump is classified according to the driving mode,and the design methods,driving principles and working characteristics of the micropump,such as piezoelectric drive,electrostatic drive,pneumatic drive,electromagnetic drive,electroosmotic drive,surface tension drive,hot bubble drive and ferrofluid drive.Several representative micropumps at domestic and overseas are introduced.Summarizing and compareing its structures,component sizes and performance parameters,and the development trend of the micropump is summarized,which will provide reference for the design of micro fluid driven micropumps in the future.The system structure and working characteristics of electromagnetic drive and ferrofluidic drive are analyzed.The manufacturing process and performance parameters of electromagnetic driving and ferrofluidic drive are compared in detail,and the development trend of the micropump is summarized,which will provide reference for the design of micro fluid driven micropumps in the future.In the second chapter,the magnetic field of the electromagnetic driven micro pump is the electromagnet.The magnetic field of the electromagnet directly affects the working characteristics of the micropump.Therefore,the theories of electromagnetic field are analyzed,including the magnetic field on the axis of the current coil,the magnetic field in the current solenoid,and the magnetic force of the current solenoid to the permanent magnet.The COMSOL software is used to simulate the magnetic field distribution of the current carrying solenoid.In order to overcome the shortcomings of the electromagnetic driving micro pump,such as complex process,high cost and large volume,an electromagnetically actuated tube type micropump was designed.The micropump was made by MEMS process.The test system of micropump is designed and built,and the flow rate and backpressure of the micropump are tested.When the working current is 0.6A,the electromagnetic driving force of the micropump is about 1.32 mN.When the working current is 0.3A,0.4A,0.5A,and the driving frequency is 5Hz,the maximum flow rate of the micropump is 194.15μL/min,201.23μL/min and 208.75μL/min,and the maximum back pressure of the micropump is 490 Pa,519.4Pa and 539 Pa.Compared to other planar film structures,the electromagnetic driven micropump has higher reliability,smaller volume,no dead volume,easier to manufacture,and less coil turns.In the third chapter,the magnetic field of the ferrofluidic driven micropump is the permanent magnet material.The ferrofluid is magnetized by the permanent magnet,thus producing the magnetic force.The working characteristics of the ferrofluid directly affect the performance of the micropump.Therefore,the classification of the ferrofluid and its material properties are summarized.In order to overcome the disadvantages of ferrofluidic driven micropump,which is difficult to realize large pump flow and difficult to manufacture,a ferrofluid driven micropump with C shaped baffle structure is designed.The micropump is made by MEMS technology.The FLUENT software is used to simulate the flow velocity of the micropump.A test system of micropump is built,and the pump flow and back pressure of micropump under different driving frequency are tested.The maximum pumping flow is 49.32μL/min,and the maximum pumping backpressure is 1125.9Pa.Because the external drive system with permanent magnet is reusable,the micropump only needs PDMS top cover,glass substrate and a small amount of ferrofluid,and the cost is low.Therefore,the ferrofluidic driven micropump can be applied to the experiment of microfluidic system which needs multiple applications.The advantages of the micropump assembly are not only reducing the complexity and cost of the manufacturing process,but also improving the reliability of the micropump.