Liu Yaxiong

Preparation of chitosan–gelatin hybrid scaffolds with well-organized microstructures for hepatic tissue engineering

The structural organization of natural liver is instrumental in the multifunctionality of hepatocytes, and mimicking these specific architectures in tissue-engineered scaffold plays an important role in the engineering of an implantable liver equivalent in vitro. To achieve this goal, we have developed a novel fabrication process to create chitosan-gelatin hybrid scaffolds with well-organized architectures and highly porous structures by combining rapid prototyping, microreplication and freeze-drying techniques. The scaffolds obtained not only have analogous configurations of portal vein, central vein, flow-channel network and hepatic chambers, but also have high (>90%) porosity, with the mean pore size of 100microm. Swelling and degradation studies showed that the scaffold has excellent properties of hydrophilicity and biodegradability. A hepatocyte culture experiment was conducted to evaluate the efficiency of the well-defined chitosan-gelatin scaffold in facilitating hepatocyte growth in the inner layer of the scaffold in vitro. Scanning electron microscopy and histological analysis showed that hepatocytes could form large colonies in the predefined hepatic chambers, and these cavities could the completely filled with hepatocytes during 7 day culture. Albumin secretion and urea synthesis further indicated that the well-organized scaffolds were more suitable for hepatocyte culture.

Fabrication of customised maxillo‐facial prosthesis using computer‐aided design and rapid prototyping techniques

Purpose – This paper describes computer‐aided design (CAD) and rapid prototyping (RP) systems for the fabrication of maxillofacial implant.Design/methodology/approach – Design methods for medical RP of custom‐fabricated are presented in this paper. Helical computed tomography (CT) data were used to create a three‐dimensional model of the patient skull. Based on these data, the individual shape of the implant was designed in CAD environment and fabricate by RP process. One patient with a large mandible defect underwent reconstruction with individual prefabricated implant resulting from initial surgical failure with hand contoured reconstruction plate.Findings – Results shows that the custom made implant fit well the defect. Overall, excellent mandible symmetry and stability were achieved with the custom made implants. The patient was able to eat. There was no saliva drooling after the reconstruction. The operating time was reduced.Research limitations/implications – The methods described above suffer from ...

Customized design and manufacturing of chin implant based on rapid prototyping

Purpose – To develop a computer‐assisted prefabricated implant design and manufacturing system to improve the esthetic outcome in chin surgery.Design/methodology/approach – Design methods for medical rapid prototyping (RP) of custom‐fabricated chin augmentation implant are presented in this paper. After a careful preoperative planning based on cephalometric tracing for esthetic assessment, helical computed tomography data were used to create a three‐dimensional model of the deficient mandible. Based on these data, the inner surface of the prosthesis was designed to fit the bone surface exactly. The outer geometry was generated from a dried human mandible to create anatomically correct shape prosthesis. The inner and outer surfaces were then connected, and a solid model resulted. A RP system was used for production of the physical models. The surgical planning was performed using the implants and skull models. The resulting SLA implant is used for the production of a mold, which is used to cast the titaniu...

The customized mandible substitute based on rapid prototyping

Traditional standard bone substitutes cannot realize the individualized matching for the bones of different patients. In order to make a bone substitute match the shape of a patients bone easily, a technology based on reverse engineering (RE) and rapid prototyping (RP) is put forward to design and fabricate a customized bone substitute. By RE, the customized bone substitute is designed according to the CT sectional pictures, and the customized localizer is designed to locate the customized bone substitute in the patients body at the right position. A customized mandible substitute designed and fabricated by RE and RP has been put into clinical use and is discussed in detail. The results confirm that the advantage of RP in the field of bone restoration is that it can fabricate the customized bone substitute rapidly and accurately.

A new slicing method of reverse engineering based on the principle of refraction and reflection

The traditional slicing method of reverse engineering has been used in product measure from time immemorial. This method however has the disadvantage of low contrast of the cross-sectional pictures of an object. In order to overcome the said shortcoming, a new slicing method of reverse engineering, based on the principle of refraction and reflection of a prism, has been propounded. According to the reflectivity of the object, one of the illuminating methods—straight illuminating or inclined illuminating—is adopted. These methods can enable one to obtain the image of the cross-section of a bright object with a dark background or the opposite. Experiments have proved to show the advantages of this new slicing method for high contrast of the cross-sectional pictures. To eliminate geometrical distortions caused by the refraction and reflection of the prism, a mathematical transformation model can be set up to correct the image by using relevant software. Eventually, a RP model of a temporomandibular joint fabricated according to its slicing pictures is illustrated.