The Construction Of Coaxial Electrohydrodynamic Jet Printing Platform And Experimental Research

Printing is a technique that uses local energy field to pattern the structure and device on the substrate directly with functional material, which has huge potential and advantages on the complex structure of micro-nano structure manufacturing. Electrohydrodynamic jet printing (E-jet printing) is an effective method for the preparation of the fine structure, with characteristics of precise stable jet, high resolution, wide material adaptability, etc. In this paper, firstly the spray current during the E-jet printing process was measured and analyzed. Secondly the coaxial print head was designed and manufactured. Then, the experiment of coaxial electrohydrodynamic jet printing was carried out by utilizing the print head.First of all, the experimental device for measuring the spray current generated by E-jet printing has been set up and the relationship between the liquid flow rate and the spray current and the jet diameter was analyzed. It was found that the spray current and the size of jet diameter increase as the liquid flow rate increases. According to the classic scaling laws of electrospray given by Ganan-Calvo, graphene nano-suspension was chosen as experiment materials. The equations of flow rate and spray current and the equation of flow rate and jet diameter were established. On the basis of the equations, the graphene line arrays were printed on the silicon substrate and the value of measured current well matches the predicted value. In addition, the graphene membrane electrohydrodynamic deposition was studied, which used to prepare the silicon-graphene composite micro heat pipe. Then, the coaxial print head was designed and manufactured and coaxial electrohydrodynamic jet printing platform system was also built. The coaxial print head not only realizes the concentricity and exchange between the inner and outer needle, but also realizes precision adjustment on the relative position of inner and outer needle. The print platform system can meet key parameters to adjust and control, such as the flow rate, voltage and working distance, which meets the requirement of coaxial e-jet printing.Finally, the influence of key coaxial e-jet printing parameters on printing modes and structures was systematically studied. It was found that the liquid viscosity, flow rate and spray needle diameter have a great influence on the coaxial e-jet printing. As the viscosity of outer liquid increases, the stability of coaxial jet and the focus of outer liquid as well as linear of printing structure enhance greatly. As the outer liquid flow rate reduces, the jet diameter size and the printing size of double-layer structure decrease. As the inner liquid flow rate reduces, the size of formed structure size significantly reduces. As the needle size is reduced, the resolution and consistency of print structure enhance. In addition, the influence of voltage on the coaxial jet model was studied and the chart of voltage range under different jet mode also was obtained. Then silica nano-suspension and PZT Sol were selected to conduct coaxial e-jet printing. The sub-micron structures of points and lines, which made by SiO2 and PZT, were printed by using a nozzle with a 50?m inner diameter, through the optimization of jet parameters. Compared to the single needle printing, the ratio of needle diameter and print size (diameter reduction ratio) is 160, which has a huge increase on the printing resolution and diameter reduction ratio.