流体微挤出/堆积制备组织工程支架过程形态调控机理研究

In this project, the dynamic process for preparation tissue engineering scaffold based on fluid micro-extrusion/stacking is researched. To overcome the drawbacks of scaffold prepared by RP techniques such as the over-size of pore and low porosity, it is raised a modeling and control schemes coupling multi-field, multi-parameters for the fabricating process , and the strategies are carried out as follows:1)Deeply research the material' rheological characteristic in the process of extrusion, distribution, spreading and cross linking, and the law of its influences on scaffold structure morphology; 2)Develop the extrusion- flow-prediction model of scaffold material under micro/nano dimension as the foundation of flow control; 3)Create the form-prediction model based on the fabrication process under multi-physic fields to support the theoretical basis for scaffold form control; 4)Formulate the decoupled control strategies of scaffold form, research the compensation control schemes to cooperative control the material extrusion flow, spreading and cross linking, micro-pipe/nozzle's motion in order to improve the morphology index of scaffold's prototyping for once. It is explored deeply that the mechanism and key technology of preparing the tissue engineering scaffold based on micro-extrusion/stacking in theory, at the same time, it is provided the guidance for the optimization of scaffold's preparation in practice. Therefore, the project has a profound academic meaning as well as a realistic application prospect.

以基于流体微挤出/堆积制备组织工程支架过程为研究内容，为克服现有利用RP技术制备的支架孔隙尺寸偏大、孔隙率难以提高的缺陷，提出面向制备动态过程的多场、多参数耦合建模与形态补偿控制研究方案，并制定如下策略：1）多物理场下支架材料非线性流变学特性表征，深入研究支架材料在挤出、布施、铺展、交联过程中的流变学行为及其对支架微观孔隙结构形态的影响规律；2）构建微/纳尺度下支架材料微挤出流量预测模型，作为流量控制的基础；3）构建多物理场下面向制备过程的支架形态预测模型，为形态控制提供理论依据；4）制定面向制备过程的支架形态解耦控制策略，研究挤出流量、材料铺展交联、微管/喷头运动协同补偿控制方案，以提高支架一次成形的结构形态指标。在理论上对基于微挤出/堆积制备组织工程支架的机理和关键技术进行深入探索，在应用上又为困扰高孔隙率组织工程支架制备技术优化提供指导。因而，项目具有深远的学术意义和现实的应用前景。

本项目以3D打印过程为研究对象，重点研究了多物理场下组织工程支架材料非线性流变学特性，在此基础上，综合考虑微尺度壁面滑移、粘性耗散的影响，建立了微尺度下3D打印流量预测模型，并给出了模型参数的标定方法；研究了微滴喷射打印过程挤出、布施、铺展、沉积过程中的流变学行为，建立了多层微滴固化时间预测模型，并深入研究了固化时间、固化角、微滴间碰撞速度、基板温度等对多层微滴固化性能的影响；在研究支架打印材料物理特性基础上，研究了打印工艺参数及材料特性对微滴可成形性、支架微观结构的影响规律，建立了结构预测模型，实现了对支架孔隙尺寸和孔隙率的预测，并揭示了对支架微孔尺寸的调控途径及规律；在以上研究基础上，进一步探索了3D打印宏观尺寸进行预测与控制的方法，以打印直线轮廓为对象，研究并建立了微滴尺寸、打印速度、加速度、频率、喷嘴与打印层距离综合影响下的构件宏观尺寸构成及其影响因素的作用规律，为打印支架的尺寸控制提供了理论支撑。以上研究对基于微挤出/堆积制备组织工程支架的机理和关键技术进行了深入探索，在应用上又为困扰高孔隙率组织工程支架制备技术优化提供指导，同时还可为其他需要对粘性流体微量精密配发的过程提供指导。因而，研究结果具有一定的学术意义和现实的应用前景。