Numerical Simulation Of Coaxial Electrohydrodynamic Jet And Printing Experimental Research

Electrohydrodynamic jet(E-Jet)printing,as a new type of printing manufacturing method,can be used to print high-resolution microstructures(<1?m),making it a research hotspot for domestic and foreign experts.However,it is difficult to break the resolution to the nanoscale(<100nm)due to the limitation of the properties of solution and the needle size.In addition,there are many factors that affect the stability and the printing results of E-Jet,including the voltage applied to the needle,the printing height,the flow rate of solution,the solution properties(viscosity,density,relative permittivity)and so on.These factors increase the cycle and difficulty of the printing experiments.Therefore,this paper first carried out the numerical simulation of the coaxial electrohydrodynamic jet(coaxial E-Jet)and the effects of key parameters on the printing results were obtained through the simulation results.Then coaxial E-Jet printing experiments were carried out using coaxial needles designed and manufactured by own and nanostructures with a size of less than 100 nm were printed.Firstly,numerical simulation of coaxial E-Jet was performed in this paper.A force model was established for coaxial E-Jet and the effects of each force on the jet were analyzed.The motion equation,the electric field equation and the interface tracking equation between fluids were derived using the Navier-Stokes equation and the Maxwell pressure tensor method.The physical model was transformed into a geometric model and boundary conditions were set.The numerical simulation of the coaxial E-Jet was performed to analyze the influence of the key printing parameters on the jet and the impact of the needle voltage on the jet was studied.The results show that the jet diameter is inversely proportional to the voltage and is proportional to the printing height and the inner flow rate.Then,different needles were simulated and a coaxial needle was developed for coaxial EJet printing experiments.The needle was simulated to obtain the optimal shape and length of the needle.A reasonable coaxial needle structure was designed,which can adjust the coaxiality of the coaxial needle and the length of the inner and outer needles to ensure the stability of coaxial jet and the uniformity of printing results.Adjustment accuracy reaches 0.01 mm.The corresponding accessories were processed and purchased to complete the assembly and debugging of the coaxial E-Jet printing needles.The coaxial needle fixture was designed to achieve the fixation and adjustment of the inner and outer needles.Finally,the simulation results were used to guide the printing experiments.The coaxial EJet printing experiments were carried out and the experiment results were compared with the simulation results to verify the correctness of the simulation model.The coaxial E-Jet printing experiments were carried out by using the photoresist and PZT sol as the inner liquid and the high-viscosity silicon oil as outer liquid.The inner needle with a diameter of 130 um was used.At last,nanoscale photoresist line arrays(200nm)and PZT line arrays(85nm)were formulated respectively by optimizing the key parameters through the simulation.