Controllable Droplet Generation At A Microfluidic T-Junction Using Electric Field

Microfluidic technology is a technology that precisely controls and manipulates microscale fluids,and plays an important role in chemical analysis and biomedicine.Droplet microfluidic technology has been developed for many years and is based on continuous discontinuous flow microfluidic technology developed by the flow microfluidic system,that is,the technology uses two mutually incompatible fluids to generate discrete microscale droplets through some way or method.This technology has the advantages of high throughput,small volume,saving samples,and no crosscontamination,so it is widely used in many fields such as cell analysis,drug screening,molecular diagnostics,chemical synthesis,and nanomaterial preparation.This technology uses the controlled production of droplets in the microfluidic channel and combines a series of subsequent operations,which has reached our complex needs in actual engineering.Controlling the size of microfluidic droplets is particularly important in many fields.The size of microfluidic droplets is determined by the geometry and flow of the microfluidic channel.Therefore,we must increase the complexity of the microfluidic chip.To achieve more external control,such as using thermal or magnetic effect systems to achieve the purpose of control,but these methods have strong limitations in the biological field.Therefore,using an electric field to drive and control is a very promising method.First,the integration of the electrodes on the microfluidic chip can be completed using simple techniques.Second,the method of driving and controlling is relatively simple and easy to operate.In addition,we know that the structure of droplets can be divided into three types:(1)T-type structure;(2)flow convergence type;(3)coaxial focusing method,where the T-type structure is to generate microfluids The most commonly used method of droplets.Therefore,this article mainly studies the influence of electric field on the generation of microfluidic droplets in T-structures,to accurately control the generation of microscale fluids,and to apply the principle of impact to the actual generation of microfluidic fluids on demand Drops in the system.This paper mainly studies the difference between the effects of alternating current(AC)and direct current(DC)electric fields on the generation of microfluidic droplets,and uses theory to explain why they differ.At the same time,it compares Newtonian fluids and non-Newtonian fluids What is the difference between the fluids,and it is found through comparison that the conductivity of the dispersed phase in the electric field affects the generation of microfluidic droplets.Secondly,we found that under the effect of AC electric field,the frequency of the electric field also affects the generation of microfluidic droplets,but the effect is different for dispersed phases with different electrical conductivity.Therefore,in the T-shaped structure,the influencing factors that affect the generation of microfluidic droplets are the frequency of the electric field and the conductivity of the dispersed phase.Finally,we use the equivalent principle of dielectric capacitance to study the complex three-dimensional model of the T-shaped structure into a simple two-dimensional circuit model.The theoretical calculation and calculation of the power supply frequency and the dispersed phase conductance are performed.How the rate affects the generation of microfluidic droplets,and the relatively accurate prediction of the critical conductivity of the dispersed phase when the T-structure reaches the PDMS wall breakdown voltage validates the reliability of our model.