| Micro/nano additive manufacturing has shown great application prospects in new energy devices(supercapacitors,micro batteries),tissue engineering,new generation electronic products(conformal circuits,wearable devices,3D structured electronics)and other fields,because of its unique advantages in the rapid prototyping of complex micro/nano structures and high material utilization.And electrohydrodynamic jet printing(EHD jet printing)has become the most popular micro/nano additive manufacturing methods for the advantages of low cost,good material compatibility and high precision.However,due to the poor printing stability caused by the reduction of the electric field intensity,which leads to the limited printing height.And the jet turbulence caused by the residual charge,have also become a huge problem for EHD jet printing.To solve the above typical problems,our research group has proposed the electric-field-driven jet deposition 3D printing technology(EFD jet 3D printing),which has been successfully applied in the fields of manufacturing multi-layer biological scaffolds and transparent electrodes with large aspect ratios.It shows that the stability of the electric field and the resolution of printing in the EFD jet 3D printing are significantly improved compared to the traditional EHD jet printing.On the basis of the above research,this paper establishes a theoretical model to analyze the change of electric field,aiming to solve the problem of electric field generation in electric-fielddriven micro/nano 3D printing technology.And a series of experimental results has proven that electric-field-driven jet 3D printing has advantages in maintaining electric field stability and jet stability.The main contents and innovations of this paper are as follows:(1)The relationship and difference between electrohydrodynamic jet printing and electric field-driven jet deposition micro-nano 3D printing is compared and introduced,and a theoretical analysis model for the electric field-driven jet deposition micro-nano3 D printing technology is established,including: initial electric field,composite electric field,and Mechanics Equations.The experimental parameters corresponding to different conditions are substituted into the model for calculation,and the variation trend of the space electric field during the printing process is obtained.(2)The theoretical model is verified by physical simulation and a series of experiments.The finite element model is established by COMSOL physical simulation software,and the established theoretical model is preliminarily verified by compared with the simulation results.The difference between the specific values of the two is always about 8%,and the rate of change of the electric field strength calculated by the two is nearly the same with different deposition thicknesses,which preliminarily verifies the applicability of the theoretical model.The experimental results show that in the process of increasing the printing height from 1mm to 3mm,the line width of the deposited structure in EFD 3D printing and EHD printing decreases by 16.9% and41.6%,respectively.On this basis,combined with the line width of the deposited structure under different voltage conditions and Taylor cone topography at the nozzle tip to characterize the variation trend of the electric field intensity during the actual printing process,and compare it with the results obtained from theoretical calculations.Then,the applicability of the theoretical model in different experimental parameters is further verified,and it is also proved that the electric field driven jet deposition 3D printing technology has higher efficiency when the voltage and printing height are changed.(3)The electrostatic deflection of the jet in EFD jet deposition 3D printing and EHD jet printing was investigated.By calculating the actual printing period of the prepared wire grid structure,the deflection of the jet on the conductive substrate and the non-conductive substrate in EFD 3D printing was shown to be negative.And the trends of jet deflection of the two printing methods in different printing substrates,different structure line widths and different printing heights were analyzed,and it was proved that the electric field-driven jet deposition 3D printing technology has the ability to prepare devices with higher resolution and more uniform structure.On the basis of the experimental results,an analytical model is established for the deflection of the jet in different substrates,different line widths and different printing heights,which provides a theoretical basis for further research on how to improve the printing accuracy.(4)The surface potentials of the printed structures prepared by the two printing techniques were measured by a surface potential tester,for different printing substrates and different voltage conditions.The experimental results prove the existence of residual charge in the deposition structure,and analyze the variation trend of residual charge in different experimental parameters,which lays a foundation for establishing a theoretical model of jet deflection. |
