Study On Droplet Formation Of Double Emulsion By Flow Focusing And Its Influence On Temperatur

Microfluidic technology has been widely used in the field of analytical science due to its superior controllability of liquid droplets.As a new technology,it has been favored by a large number of scientific researchers.As a typical type of micro droplets,double lotion droplets have been studied and developed by many scholars due to their structural characteristics such as low cross contamination and encapsulation effect.However,at present,the effect of dual lotion drops prepared by quasi two-dimensional channel flow focusing on microfluidic chips is far less than that of dual lotion drops prepared by coaxial focusing.However,because of its complex assembly,the coaxial focusing equipment requires high precision in manufacturing process,which is not conducive to the development of dual lotion drops.Based on this,the research on microfluidic chips which are easy to manufacture and efficiently prepare double lotion droplets has great research value.The main research content of this article includes the following parts:(1)Combined with the existing coaxial focused structure,the quasi-two-dimensional microchannel structure is designed according to its two-dimensional structure.At the same time,the corresponding numerical calculation model is established according to the microcurrent structure,and the numerical simulation method is introduced to verify the feasibility of the model.Build the experimental platform to determine the experimental materials,experimental instruments and devices,record the experimental data and compare and verify the numerical simulation calculation results,and determine the division grid of the numerical calculation model and the physical parameters of the calculated materials.Introduce the dimensional analysis method,determine the evaluation parameters,and get the expression of the influence parameters,as the reference formula for the subsequent articles.(2)Analyzing the influence of outer phase flow,intermediate phase flow,inner phase flow,each phase viscosity and interfacial tension on the double emulsion droplet forming process and area and forming distance,The dimensional analysis is used to fit the obtained data to obtain the specific parameter expression,As found by the analysis and comparison,Changes in the flow rate had the greatest effect on the area of the double emulsion droplets,The increase in the intermediate phase flow rate can increase the shell area to 94%;The increase of the internal phase flow rate can increase the core area by 78%;The viscosity of the three phase has more influence on the generating position than the other two parameters;However,interfacial tension influences the shape of double emulsion droplets,With the increasing interfacial tension,The shape shrinks from elastic to round.In this paper,the success rate of double emulsion droplets is 50% higher than that of traditional structures.(3)The structural parameters of the designed microfluidichannel were determined,and the influence of parameter changes on the molding process,area and forming distance were studied.In particular,the effects of the antenna,contraction ratio,outlet broad angle and the length of the mixed flow channel between the middle phase and the inner phase are analyzed.With the increase of the contraction ratio,the convection type affects and the area increases by nearly 50% and the forming distance decreases by nearly 1mm.(4)The temperature of each phase is controlled separately,and the changes of viscosity and interfacial tension are caused by the temperature difference,thus affecting the area and formation position of the double emulsion droplet.The temperature change of the middle phase and the outer phase causes the alternating change of the double emulsion droplet area.With the temperature reaches equilibrium,the droplet also decreases from 0.12mm2 to0.07mm2.Temperature has little influence on the forming mode of double emulsion droplets,and in the presence of large temperature difference between phase temperatures,the difficulty of forming double emulsion droplets increases,that is,the viscosity and interface tension of each phase are not changed,and the double emulsion droplets are unstable.