Piezo-electrohydrodynamic Nozzle Design And Printing Equipment Development

Electrohydrodynamic jet printing is a new type of inkjet printing technology that applies an electric field between the nozzle and the substrate to “pull” the solution out of the nozzle,enabling micron to nanoscale resolution.Currently available on the market,the frequency of the electrohydrodynamic printing equipment is limited by the process limitations of the electrohydrodynamic jet printing when realizing the DOD jet printing,so the printing efficiency is low.;Conventional ink-jet printing can achieve up to 20 KHz print frequency through piezo-electric drive or thermal bubble drive,and the printing efficiency is higher,but the piezoelectric ink-jet printing is limited by the size of the nozzle and its resolution is only up to 30μm..This paper proposes a high-efficiency,high-resolution piezoelectric nozzle driven by a mixture of “squeezing” piezoelectric and “stretched” currents.The nozzle uses a piezoelectric diaphragm to drive the solution during the printing process.A meniscus is periodically formed at the nozzle,and an electric field is applied between the nozzle and the substrate to form a Taylor cone in the meniscus and further form a cone jet.Therefore,the nozzle has high resolution and high-frequency jet performance.It is of great significance to the industrial application of electro-jet printing.The main work of this paper includes:(1)The dynamic model of piezo-actuated diaphragm in the piezo-electrohydrodynamic nozzle was established,and the key factors influencing the internal volume change of the cavity in the ink jet process were analyzed;Piezoelectric ink jet,electrospray dot jet,piezoelectricity The integrated jet printing process was simulated by finite element method,revealing the jet formation process,printing process parameters,jet frequency,and jet volume of the three jet printing modes.It was verified that the piezo-electrohydrodynamic nozzle can be combined with both high resolution and high frequency.(2)The structural parameters of the piezo-electrohydrodynamic nozzle were calculated by numerical simulation and theoretical model.Based on the piezoelectric diaphragm mechanics model,the parameters of the piezoelectric diaphragm satisfying the design requirements of the nozzle were obtained.The ideal size of the nozzle was obtained through the dynamic model of the piezoelectric diaphragm and numerical simulation.Then the axial dimension of the piezo-electric nozzle was obtained using the fluid dynamic model and the acoustic model,and the section shape of the ink supply chamber and the nozzle was optimized.Finally,a piezo-electrohydrodynamic nozzle was designed and fabricated,And integrated into the self-developed electrohydrodynamic printing prototype equipment for performance verification.(3)Developed a desktop integrated electrohydrodynamic printing software system ME-JET DT that is highly integrated and compatible with piezo-electrohydrodynamic jet printing.Detailed analyzed the hardware composition and index of the desktop electrohydrodynamic printing platform,described the desktop electrohydrodynamic printing platform software system requirements and build a software system framework,using shared memory technology to improve the software data processing capabilities,and memory Pool technology improves the overall stability of the software.Test results show that the above-mentioned two key technologies with good results.(4)A systematic verification experiment was performed on the piezoelectrohydrodynamic nozzle using the desktop electrohydrodynamic printing platform and the ME-JET DT software system.The high-speed camera shooting process and the observation of the lattice deposited on the substrate by the microscope demonstrated that the developed piezoelectric-electron body jet reached a high frequency of 5000 Hz;in the resolution characteristic experiment,a piezo-electrohydrodynamic nozzle is used to perform electrohydrodynamic jet printing and piezo jet printing at frequencies of 500 Hz,1000Hz,2000 Hz,and 2500 Hz respectively.The diameters of the dots deposited on the substrate were counted,and the statistical results show that the electrohydrodynamic inkjet printing has a higher resolution than the piezo ink-jet printing.