Research On Hybrid Filling Path Planning Method Of Hydrogel Extrusion For Biological 3D Printing

With the increasing demand for high-quality medical technology,3D printing technology has been widely used in the field of tissue engineering,and biological 3D printing technology emerges as the times require.The emergence of this technology has contributed to the research of tissue engineering and provided new ideas for the solution of medical problems such as donor organ shortage and transplant rejection.As a key part of biological 3D printing technology,printing path planning directly affects the accuracy,efficiency,intensity and cell activity of printing.The current 3D printing path planning methods have the advantages of fast planning speed and strong applicability.However,for hydrogel materials,problems such as overfilling and wiredrawing are easy to occur in the printing process,and the continuity of the printing path will affect the cell activity of hydrogel printing.Therefore,the low contour printing accuracy and path continuity of traditional path planning cannot meet the needs of hydrogel biological3 D printing.Developing a suitable path planning method for hydrogel biological 3D printing can improve the printing accuracy and cell viability of biological tissue models.This dissertation analyzes the existing problems in path planning of hydrogel extrusion biological 3D printing,studies the hybrid filling scanning method from the perspective of contour printing accuracy and path continuity,and proposes a hybrid filling path planning method based on Euler circuit.The main research contents of this dissertation are as follows:Firstly,the data analysis of 3D printing model file and slicing algorithm are studied.By constructing the mathematical model to solve the intersection line between spatial triangle mesh and slicing plane,and using the binary search algorithm,the fast slicing of STL model is realized,and the slice contour of the model is obtained.Secondly,aiming at the external contour path of the hybrid filling,a tissue contour path offset algorithm based on NURBS curve fitting is proposed.This method improves the printing accuracy and smoothness of the contour path of the tissue model,reduces the overfilling phenomenon of the hydrogel printing at the smaller angle of the contour line,and constructs the regional contour for the internal filling.Thirdly,the internal filling path of the hybrid filling is studied.Based on zigzag filling path,an adaptive region filling path planning algorithm based on Euler circuit is proposed.The exact cellular decomposition is used to realize the segmentation of the internal filling area.The sub regions divided by exact cellular decomposition are transformed into the Reeb graph,and the Euler circuit is constructed based on the Reeb graph to determine the filling order of the sub regions.At the same time,the adaptive filling templates for the sub regions filling are designed,and finally the highly continuous internal filling paths are obtained.Finally,combining the tissue contour path offset algorithm based on NURBS curve fitting with the adaptive region filling path planning algorithm based on Euler circuit,a hybrid filling path planning method based on Euler circuit is obtained.Taking human nasal tissue model as an example,through simulation and hydrogel printing experiments,it is proved that this method can improve the continuity of internal printing paths and the overall printing accuracy of printed products.