Design And Experimental Research Of Multi-Axial Electrohydrodynamic Direct-Write System

As an emerging micro/nano jet printing technology,Electrohydrodynamic Direct-Write(EDW)has a wide range of applications in micro/nano sensors,biological engineering,new materials and other fields for its easy to process,good flexibility and good material compatibility.Overcoming the disturbances in patterned deposition,establishing the online controlling strategy to improve the deposition accuracy and uniformity,promoting the precise direct-write printing of functional micro/nano patterned structures,has become the key to the industrialization EDW applications.In this work,an integrated control system of EDW is established.The movement and the electrical behavior of the ejecting jet are studied.A closed loop control system for EDW is built to realize precise patterned deposition.Applications of functional direct-written patterns are explored.An EDW platform with visual and current testing is established.The electrospinning current and jet evolution behaviors are studied.The controlling parameters of EDW such as applied voltage and platform velocity are matched and optimized.It is found that with the increase of applied voltage,the current increases and four jet ejection modes occur sequentially:droplet ejection mode,Taylor cone ejection mode,retractive ejection mode and forked ejection mode.Inhibition of electrospinning current fluctuations helps to reduce the distribution range of electrospun nanofiber diameters.The Taylor cone ejection mode is suitable for long time stable direct-writing.Continuous stable and uniform micro/nano patterns can be obtained when the velocity of platform is 12.6-23.3 mm/s.An integrated EDW system which contains both completed multi-axial direct-writing movement platform and integrated control software is constructed,through which the detection and real-time monitoring for EDW parameters including electrospinning current,jet morphology,collecting plate moving velocity and trajectory,is realized.Fuzzy control algorithm is introduced into the self-adapting closed-loop control program,which enables closed-loop control of both the current and the jet mode.Construction of closed-loop control system greatly enhances the stability of EDW jet.With the double feedback of the control system,the distribution range of fiber diameters reduces by 70%,and the fluctuation range of current reduces from 35%to 14%.Based on the advantages of accurate patterned deposition and facilitation for complex patterns,direct-writing of functional patterns is explored to print band and annular velocity encoders..Experimental results for velocity measurement show that the error of band encoder is less than 4.76%,and 1.65%for the annular encoder.In this paper,a closed loop control system for EDW is developed.The precise printing of jet ejection and the controlling law of micro/nano pattern direct-writing are investigated.Accurate patterned deposition of EDW and printing of functional micro/nano structures are achieved.The proposed system is promising in the promotion of the industrialization of EDW technology.