| Ink jet printing technology is a kind of technology that disperses ink into tiny droplets and forms patterns on the substrate.It originated in the field of ink-jet printing,but with the development of science and technology,it has been gradually applied in the fields of electronics,building materials,medicine,cell engineering and so on,and has become an important part of modern advanced manufacturing technology.Ink jet printing technology is mainly divided into continuous ink-jet printing technology,hot bubble ink-jet printing technology and piezoelectric ink-jet printing technology.The core of the technology is to generate various micro droplets with the volume of micro rise to flying rise through the orifice.However,when the diameter of the orifice is less than 20 μm,it is easy to cause blockage,and the manufacturing of micro pores is expensive and complicated,It greatly limits the application of printing technology in the field of microelectronics and the development of printing electronic industry.Aiming at the above problems of traditional inkjet printing,a satellite droplet ink-jet printing technology with symmetrical nozzle based on Plateau–Rayleigh Instability theory is proposed,and a systematic and in-depth research work is carried out,and the following innovative results are achieved.A satellite droplet printing system based on symmetrical nozzle was developed.The piezoelectric ceramic was driven by electric signal to deform under the effect of inverse piezoelectric effect.The ink in the liquid storage chamber was squeezed to the nozzle through the symmetrical channel and formed a liquid bridge.During the deformation recovery process of piezoelectric ceramic,the liquid bridge broke and formed satellite droplets.The droplet generation method,which is completely different from the traditional ink-jet printing technology,solves the problem that the traditional ink-jet printing method can not print small droplets with large-size orifices,and can prepare droplets less than ten or even dozens of times of the diameter of the orifices.Under the same orifice size,the droplet volume can be reduced by 3-5 orders of magnitude,which is crucial to broaden the application of ink-jet printing in the field of printing electronics and reduce production costs.In this paper,the effects of liquid properties,liquid bridge length and piezoelectric ceramic driving electrical signal on the formation process of satellite droplets are studied.It is found that the surface tension coefficient has little effect on the size of satellite droplets,but the bounce amplitude and frequency of satellite droplets increase with the increase of surface tension coefficient;High viscosity will make the liquid bridge thinner and longer,which is not conducive to the stable formation of satellite droplets;The experimental results show that the fracture process of the liquid bridge is affected by the length of the liquid bridge,and the critical point of the transition from symmetric state to asymmetric state is obtained.The diameter of the satellite droplet increases with the increase of the length of the liquid bridge until the ratio of the length of the liquid bridge to the diameter of the nozzle exceeds 2π;Compared with triangle wave and sine wave,square wave is easier to generate satellite droplets,high frequency is easier to generate satellite droplets continuously,and the diameter of satellite droplets increases with the amplitude.The formation mechanism of satellite droplets is revealed through the simulation of the formation process of satellite droplets;Based on the study of the formation process of the satellite droplet of the approximate inviscid fluid,it is proposed for the first time that the critical instability state profile of the static long liquid bridge of the approximate inviscid fluid can be approximated by the sine curve,and the geometric interpretation of the spindle formed at the critical moment of the liquid bridge can be approximated by the arc is given for the first time,and the length diameter ratio of the spindle is always slightly greater than 2π. |
