生物玻璃陶瓷骨支架的光固化成形工艺与过固化研究

Forming Process and Overcure of Bioglass Ceramic Bone Scaffold by Photocuring Technology

针对光固化技术制备生物玻璃陶瓷多孔骨支架中因光散射、光叠加等原因导致内孔扩散的过固化问题,提出从“孔-面-体”3个层面来探究样件成形过程中过固化现象与工艺参数间关系的方法,并逆向建立克服过固化提高精度的多孔补偿模型。首先,采用激光共聚焦测量了骨支架中单孔在不同曝光时间和石墨浓度下的过固化值与固化深度;其次,在骨支架的面结构中采用光学影像测量仪分析了不同面孔隙率和孔隙形状下的过固化值与固化深度;然后,使用场发射扫描电镜表征了重叠层厚对骨支架整体结构中固化特性的影响;最后,通过控制骨支架的多孔尺寸,建立过固化逆向补偿模型并制备了与模型孔径相差不大于5μm的多孔样件。采用所制备的多孔支架样件进行实验验证,结果表明:单孔结构中,过固化值和固化深度均随曝光时间的对数增加而线性增加,随石墨浓度增加而减小;在单层面结构中,过固化值和固化深度均随孔隙率的增大线性减小,孔隙形状对固化深度无明显影响;在体结构中,随重叠层厚的增加,样件过固化程度增加,叠加层厚10μm为适宜分层;在相同曝光时间和石墨浓度下,过固化从孔结构-面结构-体结构过程中逐渐增加,且孔和面结构的过固化程度显著大于体结构。该方法可为高精度多孔骨支架的制备提供一种新思路。

To solve the problem of overcure caused by light scattering light superposition and others in production of bioglass ceramic porous bone scaffolds by using photocuring technology,a method based on the three levels of“pore-layer-volume”is proposed to explore the relationship between the overcure and process parameters in the forming process of such a scaffold.Moreover,a porous compensation model is established reversely to overcome overcure and improve accuracy.Firstly,the overcure value and curing depth of a single pore in the scaffold under different exposure time and graphite concentration are measured by laser confocal microscopy.Secondly,the overcure value and curing depth under different monolayer porosity and pore geometries are analyzed by optical image measuring instrument in the monolayer structure of the scaffold.Thirdly,the influence of overlapping layer thickness on the curing behaviour is characterized by field emission scanning electron microscopy in the volume structure.Finally,an overcure reverse compensation model is established by controlling the porous size of the scaffold,and a porous test sample with a diameter error less than 5μm is produced.The prepared porous scaffolds are used for experimental verification.The results show that the overcure value and the curing depth linearly increase with the logarithmic increase of the exposure time but decrease with the increase of the graphite concentration in the single-pore structure,the overcure value and the curing depth linearly decrease with the increase of the monolayer porosity,and the pore geometries have no obvious influence on the curing depth in the monolayer structure,the overcure degree increases with the increase of overlapping layer thickness,and a thickness of 10μm can be suitable for forming in the volume structure.When both the exposure time and the graphite concentration are the same,the overcure gradually increases for the single-pore structure,the layer structure and the volume structure,and the overcure degree in the formation of the pore structure and the layer structure is significantly greater than that of the volume structure.The proposed method can provide a new idea for the preparation of high-precision porous bone scaffold.