Design And Experimental Study Of Gasassisted Electrostatic Focusing Electrohydrodynamic Printhead

Electrohydrodynamic jet printing technology has sub-micron resolution with largerange viscous inks,and has received extensive attention and application in recent years.Due to the polarization and charge accumulation of the insulating substrate and the influence of the non-planar substrate on the electric field,the printing performance of the electrohydrodynamic jet printing on the insulating and non-planar substrates is poor.In this paper,a gas-assisted electrostatic focusing electrohydrodynamic printhead is proposed.The Electric field and flow field of the printhead are theoretically analyzed and structurally designed.The gas-assisted electrostatic focusing electrohydrodynamic printhead is fabricated,which realized the accurate and stable printing of electrohydrodynamic jet printing on the insulated/non-planar substrate.This greatly broadens the range of applications for electrohydrodynamic jet printing.The main work of this paper includes:Firstly,a new type of electrostatic focusing electrohydrodynamic printhead is proposed.The theoretical model of electrostatic focusing electrohydrodynamic printhead is established,and the theoretical formula of electric field potential distribution in the printhead is derived.Then the preliminary design range of the printhead parameters is obtained.On the basis of this,numerical simulation is used to analyze the influence of printhead design parameters on the movement of charged droplets in the electric field of the printhead.The design method of the electrostatic focusing electrohydrodynamic printhead are obtained.And the feasibility of the printhead for continuous jet printing is verified by electrohydrodynamic simulation,and the reliability of the printhead design method is preliminarily verified experimentally.Secondly,aiming at the problem of jet adhesion in near-field spinning of electrostatic focusing electrohydrodynamic printhead,the gas assisted method is introduced into the printhead structure,and the model of gas assisted near-field spinning is established.The electrospinning jet is analyzed in the gas field.The force of the electrospinning jet in the flow field is analyzed.The stability of the charged jet is analyzed by the flow velocity distribution.The flow field optimization conditions for improving the jet stability are obtained.On this basis,the optimization design of the gas structure is completed by CFD numerical simulation and analysis,which provides a basis for the structural design of the printhead.Thirdly,the gas-assisted electrostatic focusing electrohydrodynamic printhead is designed and manufactured.Based on the design of electrostatic focusing and gas assisted structure,combined with simulation and analysis,the electrode structure and the overall flow field structure inside the printhead are designed.After comprehensive analysis of the design basis of each structure,the overall structure of the gas-assisted electrostatic focusing electrohydrodynamic printhead is designed and manufactured.The whole gas channel inside the printhead is analyzed by simulation,which ensures the uniformity and stability of the gas at the tip of the printhead.Fourthly,the printing performance of the gas-assisted electrostatic focusing electrohydrodynamic printhead on the non-planar/insulating substrate is analyzed and verified experimentally.Aiming at the typical printing mode(continuous direct writing,drop-on-demand printing,near-field spinning)in electrohydrodynamic jet printing,the effects of electrostatic focusing and gas assisting functions on printing performance are analyzed experimentally.On the insulated non-planar substrate,the gas-assisted electrostatic focusing electrohydrodynamic printhead realizes accurate and stable printing of three printing modes.