Development Of 3D Bio-printing System For Skin Tissue Engineering

Based on Additive Manufacturing (AM),3D bioprinting technology slices three-dimensional tissue and organ into a series of layers to bulid, which can accurately control scaffold structure and cell distribution in the scaffold and makes it easy to construct heterogeneous tissues and organs. To provide new method for tissue engineering research, this thesis does research on development of 3D bioprinting system including mechanical system, electric control system and control program, establishment of mathematical modes for the print process and combination of the simulation and the experiment to validate the feasibility of the prototype system.In this thesis, the design goal of prototype system was made based on the analysis of function and demand. The mechanism of prototype,including three-dimensional synchronous movement platform, nozzle parts, feeding system and temperature control table was designed and modeled; The design of electrical diagram for power supply, linear motor/servo motor drive and feedback, temperature control and Input to Output isolation with CMhp controller was finished; Cascade feedback control scheme with PID algorithm was establish and program design was carried ouy to control the system using ACS programming language in the SPiiPlus MMI Application Studio. Mathematical models for the flow, porosity and strand diameter was builded with constitutive equation of pseudoplastic fluid. To validate the feasibility of Mathematical models and the prototype, the simulation with MATLAB and the experiment with sodium alginate, calcium chloride solution and the fibroblast were also carried out. Simulation and experiment results showed that mathematical models are accurate to predict the printing process parameters and the prototype system has good feasibility for cell printing to contruct the organ.In chapter 1, the aim and significance of the study in this thesis were discussed. The current research progresses on 3D bioprinting technology were reviewed. The main research subjects were presented.In chapter 2, the design goal of prototype system was made based on the analysis of function and demand. Gantry drive type double nozzle system was designed based on pneumatic nozzle extrusion principle, including three dimensional motion platform, nozzle parts, feeding system and temperature control table four. The CMhp controller was choosed using ACS advanced scripting language for program to control system.In chapter 3, the mechanism including four axis synchronous drive motion platform, nozzle structure, pressure regulating feeding system and temperature control table was designed in Solidwork. Electrical diagram for power supply, linear motor/servo motor driver and feedback, valve drive, temperature control and Input to Output isolation was designed in AutoCAD. Cascade feedback control scheme with PID algorithm was used to control liner motiors. At last, programs for system configuration, motor drive, the origin calibration, valve drive and printing process was wrote in the SPiiPlus MMI Application Studio with ACS program language.In chapter 4, to study the controllability of printing process, mathematical models of the flow, strand diameter and the porosity about variables, such as the pressure, nozzle diameter, nozzle length, consistency coefficient, flow index, etc, were builded based on constitutive equation of pseudoplastic fluid. The simulation was carried out to analyze the impact of variables on the flow, strand diameter and the porosity.In chapter 5, the experiments were introuduced. The glass glue, sodium alginate solution, CaCl2 crosslinker and fibroblasts were printed to construct three dimensional composite structure. Experiment results showed that mathematical models are accurate to predict the printing process parameters and the prototype system has good feasibility for cell printing to contruct the organ.In chapter 6, conclusions of this thesis were summarized and future research proposals were suggested.