Study On Accurate Control Of Axial Bending Deposition Of Melt Near-field Electrospinning

The meandering and buckling fiber,as a kind of spring-like structure with x/y unidirectional super ductile material,has been extensively studied and used in the manufacture of stretchable/flexible electronic devices and micro-optical fibers.However,the application of serpentine structures in bio-tissue engineering scaffolds has not been deeply studied,and it is still a huge challenge to realize the precise manufacture of micro-scale high-uniform serpentine structures.The structure,morphology,mechanical properties and other parameters of meander fibers are difficult to achieve real-time closed-loop control.At the same time,the existing preparation process of such fibers also limits the precise manufacturing of the microstructure of the fiber scaffold.Therefore,there is an urgent need to propose a new strategy that can stably and accurately manufacture a meandering microstructure.Fortunately,the axial bending effect common in nature can use viscous fluid to flow on the surface of the collecting plate at a certain height,which can produce a variety of different coil patterns,such as straight lines,sinusoidal windings and "8" shapes.Using this characteristic,a serpentine structure sensor and tissue scaffold with super elasticity,negative Poisson's ratio and super ductility can be designed.In the near-field electrospinning micro-nano manufacturing process,the phenomenon of axial bending also occurs and a three-dimensional serpentine structure in space can be formed.Based on this,this paper proposes a new method for manufacturing micro-scale serpentine structures that combines melt near-field electrospinning and axial bending effect.This method uses polymer materials with low cost,good biocompatibility,and excellent degradability to manufacture high-performance composite serpentine structures based on high-viscosity molten polymer materials.The principle of this method is based on the controllable deposition of melt near-field electrospinning,and controls the spinning voltage,the moving speed of the receiving plate,the height of the needle and the diameter of the needle.And combined with the axial bending of the jet during the falling process,the serpentine deposits with different morphologies can be obtained.The main research contents of this paper are as follows:(1)A new method for preparing a serpentine structure by axial bending of melt near-field electrospinning is proposed.Mechanical analysis of jet deposition and fluid axial bending phenomenon in nature.On this basis,the axial bending phenomenon of the jet when voltage is applied is theoretically deduced.Finally,it is clarified that the influencing factors of the morphology of the melt near-field direct writing axial bending meandering are the speed of the collecting plate(V),the voltage(U),the height of the needle(H)and the diameter of the needle(D).Lay a theoretical foundation for the subsequent simulation and experimental investigation.(2)Use the simulation software COMSOL Multiphysics to simulate and analyze the axial bending process of melt near-field electrospinning.First,the Young's modulus of the molten PCL is calculated and set to simulate the jet.Then,according to the simulation principle of the electrostatic field and solid mechanics module,the electric potential and electric field distribution characteristics are analyzed,and the solid and electric field are used to simulate the meandering and buckling process of the jet.Finally,it is determined that the electric field has a positive effect on the axial bending of the jet.(3)Through experiments,the applicable scope of various influencing parameters of controllable meander deposition and the change mechanism of meander morphology with the change of parameters have been obtained.Based on four sets of comparative experiments,the influence mechanism of the change of needle diameter,voltage change,speed of receiving plate and change of needle height on the change of serpentine deposition morphology was found,and the control method of order serpentine deposition was found.Then,a two-factor three-level variance experiment was carried out,and the F value test showed that the voltage and the speed of the collector have a significant effect on the morphology of the serpentine deposit.And successfully printed flexible cell culture scaffolds for cell culture experiment.(4)The space expansion of the method of preparing meandering deposition by melt near-field electrospinning combined with axial bending effect.One is to propose a large-scale preparation method of meandering deposited fibers through the field interference simulation of the array needles and the double needle deposition experiment.The second is to propose a near-field electrospinning device with a deflection collecting plate.That is,through the deflection of the receiving plate in different directions,the combined preparation of several morphological serpentine depositions can be realized at the same time,or a serpentine deposition with gradual morphology can be obtained.