Experimental And Application Research Of High Voltage Electrostatic Focusing Electrohydrodynamic Printing

As a new technology for fabricating micro and nano structures and devices,electrohydrodynamic printing has attracted more and more attention in the past few years.However,due to the effect of high pressure on the substrate to produce electric field,the substrate constantly accumulates the charge in the liquid and the polarization problem,the pattern printed on the substrate is of poor quality when electrohydrodynamic printing is carried out.In this paper,an electrohydrodynamic nozzle based on high voltage electrostatic focusing is proposed.Theoretical analysis and numerical simulation are carried out around the electric field and flow field of the nozzle,and the high voltage electrostatic focusing electrohydrodynamic nozzle is built on the experimental platform for experiments,which provides a new method for high resolution pattern printing of low viscosity and high conductivity printing solution.The technique is also applied to the preparation of flexible ion gel strain sensor,which greatly broadens the application range of electrohydrodynamic printing technology.The main research contents of this paper are as follows:(1)By analyzing the basic equations of hydrodynamics and electrodynamics,the basic theories of electrohydrodynamic printing are systematically expounded,and the force of Taylor cone in the process of electrohydrodynamic printing and the influencing factors of cone jet are analyzed.Finally,the structure model of high voltage electrostatic focusing electrohydrodynamic nozzle is established according to the theory of electrostatic focusing.The feasibility of improving the resolution of printing pattern is analyzed.(2)According to the electrostatic focusing effect of charged particle optics,a novel high-pressure electrostatic focusing electrohydrodynamic nozzle is proposed.Numerical simulation method is used to construct the numerical model of the highpressure electrostatic focusing electrohydrodynamic jet under the coupling effect of the flow field and static electric field.The influence of the surface charge density,electric field distribution,voltage and flow velocity of Taylor cone on the jet morphology in the simulation process of high voltage electrostatic focusing electrohydrodynamic jet is analyzed.The focusing effect of electrostatic focusing electric field generated by the high voltage electrostatic focusing lens on the charged jet in the process of jet injection is verified by the simulation results.(3)In order to realize the electro-hydrodynamic printing method to prepare highresolution patterns of low viscosity and high conductivity printing solution,PEDOT:PSS mixed solution was used as printing solution,and the influence of voltage and flow rate on jet morphology was referred to in the simulation results.PEDOT:PSS wire was sprayed on paper by traditional electrohydrodynamic printing method and high voltage electrostatic focused electrohydrodynamic printing method respectively to explore the influence of different voltages and flows,as well as the substrate speed,an important process parameter in practical operation,on the printing line width.In order to more directly compare the resolution of the two printing methods,the PEDOT:PSS conductive pattern was printed on the photographic paper,and the line width of the two printing methods was compared to verify that the high voltage electrostatic focusing electrohydrodynamic method has a higher resolution of the micro-pattern printing.(4)The high voltage electrostatic focusing electrohydrodynamic printing technology is applied in the preparation of flexible ion gel sensor,the ion gel film is prepared in the PDMS mold,and then polymerized into the ion gel film with double network(DN)structure under the induction of ultraviolet light(UV).The mechanical and electrical properties of ionic gels prepared by conventional gel preparation technology were analyzed.The freeze resistance and stability of CS-(AA-HEMA)-DN ionic gel prepared by high voltage electrostatic focused electrohydrodynamic spray were tested.In addition,as a flexible strain sensor,it can also monitor the electrical signals generated by human movement at different temperatures.In conclusion,flexible ion gel flexible sensors with high tensile property,high conductivity and strong frost resistance can be prepared by high voltage electrostatic focused electrohydrodynamic printing method,which has a broad application prospect in the field of flexible electronics.