Research And Design Of Micro-Fluidic Micro-Valve Working Mechanism

In recent years,the microfluidic chip technology has developed rapidly and has been widely used in the fields of biology,chemistry,medicine,and manufacturing.The core of the microfluidic chip is microfluidic manipulation.The micro-valve in the microfluidic chip can commutate and switch the fluid in the micro-channel.The pneumatic micro-valve uses the compressed gas as the power source.The micro-valve has the advantages of fast dynamic response,simple structure,and easy integration.Therefore,the research of pneumatic microvalve has very important and important significance in the research of microfluidic system.In this paper,the thin-film pneumatic microvalve as a research object,studied from the working mechanism,microfluidic flow characteristics analysis,dynamic analysis of the diaphragm deformation,micro-valve design,manufacture,packaging and micro-valve performance test experiments.The main research content is as follows:Firstly,the application of microfluidic technology in the detection and analysis of point-of-care testing(POCT),polymerase chain reaction(PCR),PCR chip products and synthesis of nanomaterials are described.The commonly used manufacturing methods for microfluidic chips and their packaging methods are described.Based on this,the research status of micro-scale flow theory and microfluidic chip technology at home and abroad are reviewed in detail.Secondly,combined with the structural features of the normally open microvalve and the laminar flow characteristics of the microchannel,the gas drive force of the control channel,the deformation of the PDMS diaphragm,and the multiphysics coupling between fluids in the liquid channel are taken into consideration.A mathematical model coupled dynamic model of diaphragm pneumatic microvalve diaphragm was established.The gas valve was put forward as the main performance index of the key actuators in the microfluidic chip.Then,numerical analysis was performed using COMSOL Multiphysics,a multiphysics modeling software based on the finite element method.For each model,the pressure inlet and velocity inlet are used respectively to analyze the flow characteristics of the fluid in the microchannel and the deformation of the diaphragm.On this basis,a kind of stress-concentrated membrane can be designed to reduce the deformation of the diaphragm,and the dynamics of the diaphragm is analyzed.Next,combining the advantages and disadvantages of the traditional microfluidic chip processing technology,a UV curing resin(photosensitive resin)is used as a material in combination with light curing 3D printing technology.A microfluidic chip with a microchannel structure capable of meeting experimental requirements was fabricated.Combining the advantages and disadvantages of the traditional microfluidic chip packaging technology,a reversible encapsulation method for the characteristics of the pneumatic microvalve structure was designed to provide the basis for subsequent theoretical and experimental research.Finally,a test experiment system for the pressure flow characteristics and response characteristics of a pneumatic microvalve was built.The pressure flow measurement of the pneumatic microvalve was accomplished by using two different drive devices,the constant pressure pump and the syringe pump.The micro-valve pressure flow test experiment was realized under different liquid channel driving modes.Based on this,the dynamic response test experiment scheme applied to the pneumatic micro-valve was designed and the dynamic response characteristics of the pneumatic micro-valve were tested.