Research On The Liquid Infiltration And Electrohydrodynamic Jet Behavior On Silicon Tip

In recent years,with the rapid development of micro-electromechanical technology,micro-nano-scale printing technology has been widely used in the manufacture of various micro-devices.However,current electrospray printing can only increase the print resolution by reducing the inner diameter of the print nozzle,which can result in clogging of the orifice and also limit the type of electrospray print solution.In order to solve these problems,based on the traditional electrospray printing technology,a novel structure based on silicon tip-infiltrated focusing electro-jet printing nozzle was designed.The liquid infiltration on the silicon tip and its electrospray behavior were studied.(1)Based on the traditional electrospray printing technology,the structure of silicon tip infiltration focused electrospray print head was designed.The model of the designed silicon tip print head was simulated and the liquid film infiltration was analyzed.The effects of various parameters of printing solution on liquid film infiltration were discussed in detail.The response surface analysis model of printing solution parameters and print droplet size was constructed by numerical simulation of fluid mechanics and Box-Behnken method.The model was used to analyze the properties of printing solution in detail.The effect of the printing solution parameters on the print droplet size is obtained.(2)In order to prepare high-quality nano-silicon tip to improve the printing resolution,the effect of etching temperature on the shape of etched silicon tip in wet anisotropic etching silicon tip was firstly investigated.The silicon tip etch parameters were used to prepare a silicon tip with a radius of curvature of 67 nm and successfully integrated into the silicon tip printhead.At the same time,a silicon cup ink reservoir having a depth of 50 ?m and a cross beam groove having a width of 878 ?m were prepared by wet anisotropic etching as an ink supply flow path.Then,titanium metal having a thickness of 150 nm was sputtered by RF magnetron sputtering and patterned as a silicon tip electrode.Finally,the UV-modified technology was used to modify the contact angle of the metallized silicon tip surface with water from the initial 54° to the 10 ° super-hydrophilic state,and the preparation of the silicon tip print head was successfully completed.(3)According to the principle of electro-jet printing,the gantry-type three-dimensional servo motion platform was designed and the whole precision three-dimensional printing platform system was built.On the basis of the established experimental system,the capillary infiltration test in the early stage of printing was completed.The surface modified silicon tip has a good infiltration effect and meets the experimental design requirements.By printing tests on different printing solutions,structural patterns of different shapes such as dots,straight lines,spirals,etc.are obtained,and a line with a minimum line width of 2.75 ?m can be printed by using an acetic acid solution of PEO.The feasibility of silicon tip infiltration focused pulse electrospray printing technology was preliminarily verified,which indicated that the technology can adapt to the printing of physical and chemical indicators such as density,viscosity and surface tension,which can increase the type of printing ink and expand the applicable range of electrospray printing.