| The fiber prepared by electrospinning technology has the advantages of small diameter,large specific surface area and high porosity.It has a good application prospect in the field of biomedicine.In recent years,the combination of electrospinning technology and additive manufacturing has provided a new method for the preparation of biological tissue engineering scaffolds.Scaffolds with good order and high accuracy can induce cell growth,which is conducive to cell growth and tissue differentiation.Compared with the solution electrospinning,the fiber obtained by the melt electrospinning has the advantages of non-toxic and good controllability in the spinning process.The obtained fiber scaffolds can provide a better growth environment for cells and are more conducive to the preparation of the ordered cell scaffold.Therefore,it has a higher application value in the field of medical and biological engineering.At present,most of the fibers prepared by the melt electrospinning technology are in the form of unordered nonwoven fabrics,and the disordered fiber arrangement restricts the application of the electrospinning technology in the fields of biological tissue engineering and robots,which require an orderly structure.In this study,the three-dimensional motion platform was introduced into the melt electrospinning technology.By using the direct writing electrospinning controllable molding device,the preparation of the one-dimensional controllable molding parameters,the high precision two-dimensional grid structure and the high precision three-dimensional structure were studied,and the high precision three-dimensional grid structure was obtained.The main contents were as follows:1.The effect of the nozzle moving speed,the spinning voltage and the collecting distance on the controlled process of direct writing electrospinning is studied by using the direct writing electrospinning controllable molding device.It is concluded that the matching of the moving speed St of the nozzle and the ejection velocity Sj in the direct writing process of the melt is the key of the fiber ordered deposition.The critical speed of the collector is different under different voltage and receiving distance.2.In the process of two-dimensional grid preparation,the influence of the receiving distance,the spinning voltage and the charge accumulation on the controllable molding precision is first studied.The electric field intensity at the nozzle is simulated by COMSOL.It is concluded that when the electric field strength of the nozzle is less than 4kV/mm,the repulsion between the fibers is small and can be repeated.Secondly,the experimental device was improved.Based on the new device,the effect of the set spacing on the parallel fiber deposition error was studied.When the set spacing was 2mm and above,the parallel fiber deposition error was minimum and within 5%.Finally,influence of the first layer area of parallel fiber formed by the grid on second layers of parallel fiber deposition error was studied.When the area of the first layer of parallel fiber is within 225mm2,the error of the second layer parallel fiber is minimal and the error value is about 15%.Finally,when the spinning temperature is 170℃,the receiving distance is 8mm,the spinning voltage is 7kV and the feeding rate of the plunger is 80 m/s,the direct writing area is set to 225mm2 and the set spacing is 2mm,and the two-dimensional grid with the lateral precision of more than 95%and the longitudinal precision of about 85%is obtained.3.The influence of the spinning voltage and setting distance on the three-dimensional structure controlled molding is studied.Under the condition of the spinning nozzle temperature 160 ℃ and the receiving distance of 8mm,when the spinning voltage is 6kV,the receiving plate corresponds to the critical moving speed of 950mm/min and the set spacing is 1.5mm,the 3D grid can deposit 15 layers,and the accuracy of 3D mesh parameters is about 95%.In this paper,the melt direct electrospinning two generation machine was used in this paper to carry out the direct writing electrospinning experiment of the melt.The high precision three-dimensional grid structure was obtained.It will serve as cell scaffold and lay a foundation for biological tissue engineering scaffold. |
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