Rapid Prototyping

As a more advanced technique for scaffold manufacturing, rapid prototyping (RP), also known as solid free-form technique (SFF), is computer-controlled fabrication technique that can rapidly produce 3D architectures by using a layer-by-layer additive method [244, 245]. Since biomedical devices were developed by using a custom-built 3D printing (3DP) machine in the early 1990s, numerous SFF technologies, such as fused deposition modeling [246], stereolithography [247], and selective laser sintering [248] have been utilized to fabricate scaffolds. By the year 2000, computer-aided tissue engineering (CATE) has emerged to produce

Fig. 2.12 Schematic of the experimental setup [86] (Adapted with permission from Ref. [86]. Copyright 2012 Elsevier Ltd) multi-functional scaffolds. PR technology uses the computer added design (CAD) software to express the designed scaffold as a series of cross-sections [249], then lays down a layer of material from the bottom and moves up a layer at a time to build complex 3D scaffolds that correspond to each cross section. According to the state of materials before forming, the RP technology can be divided into the liquid- based, solid sheet and discrete particle technologies.

RP is an efficient to produce the scaffolds with desired properties. At present, metal, polymer and ceramic can be used as materials to create 3D models by this technology. The advantage of RP is that not only the matrix architecture of scaffolds, such as size, shape, inter connectivity, branching, geometry and orientation, but also the mechanical properties, biological effects and degradation kinetics of scaffolds can be designed similar to the original structure with different material composition [250, 251]. In addition, it is also used for the preparation of reinforced scaffolds. For example, Agrawal et al. [86] used the 3D RP technology to form crossed “log-piles” of elastic fibers that were then impregnated with an epoxy-based hydrogel in order to form the fiber-reinforced gel, as shown in Fig. 2.12. Lian et al. [252] developed a method based on RP technology to produce chitosan fiber CPC composites (CF/CPC) as scaffold materials for bone tissue engineering applications. Alge et al. [253] also used RP technology to prepare poly(propylene fuma- rate) reinforced dicalcium phosphate dihydrate cement composites for bone tissue engineering. Yong et al. [254] utilized RP technology to form collagen scaffolds reinforced with PCL/beta-TCP nanofibres to obtain the high efficiency of cell seeding and enhanced mechanical properties for bone tissue regeneration.

RP technique can be easily combined with imaging techniques to produce the scaffolds. The main inherent shortcoming of this technique is the limited material selection and inadequate resolution. Most of RP systems are too expensive, which is an important factor confining the use of RP technique. In addition, educing product costs and manufacturing time is also the long-term aim of the project.