Biomedical Engineering Reference
In-Depth Information
4
Fabrication and
Antibacterial Performance of
Graded Nano
-
Composite Biomaterials
Anping Xu and Dongbin Zhu
School of Mechanical Engineering, Hebei University of Technology, Tianjin,
China
1. Introduction
Solid freeform fabrication (SFF), also termed as layered manufacturing, produces parts
directly from a computer model without part-specific tooling and human intervention
(Sachlos et al., 2003; Leong et al., 2003; Kim et al., 2009; Dwivedi and Kovacevic, 2004; Cai et
al., 2003; Tian et al., 2002; Guo et al., 2002; Cawley, 1999; Calvert et al., 1998; Alimardani and
Toyserkani, 2008; Alemohammad et al., 2007; Li, 2005; Bryant et al., 2003). It has great
potential to fabricate functionally graded materials (FGMs).
Through selective slurry extrusion (SSE) based technique of SFF, Xu et al. successfully
fabricated multi-material dental crown (Xu et al., 2005) and further proposed a novel
approach (as shown in Figure 1), termed as equal distance offset (EDO), to representing and
process planning for SFF of functionally graded materials so as to meet the requirement of
modelling and fabricating 3D complex shaped FGM objects (Xu and Shaw, 2005).
In EDO (Xu and Shaw, 2005), a neutral arbitrary 3D CAD model is adaptively sliced into a
series of 2D layers. Within each layer, 2D material gradients are designed and represented
via dividing the 2D shape into several sub-regions enclosed by iso-composition contours. If
needed, the material composition gradient within each of the sub-regions can be further
specified by applying the equal distance offset algorithm to each sub-region. Using this
approach, an arbitrary-shaped 3D FGM object with linear or non-linear composition
gradients can be represented and fabricated via suitable SFF machines. The process
planning for SFF of FGM objects is shown in Figure 2.
In recent years, the inkjet colour printing based SFF technology has been of great interests in
tissue engineering (Calvert et al., 2007; Xu et al., 2006; Saunders et al., 2008; Sanchez et al.,
2008; Roth, 2004; Hasenbank et al., 2008; Cui and Boland, 2009), as it can fabricate 3D
complex shaped graded material with smooth gradients (Wang and Shaw, 2006).
Human teeth have some very good properties such as high hardness and wearability, good
heat insulation, high strength, etc. These properties are related to its graded structure.
Figure 3 (Tooth anatomy, (2011). http://www.mydr.com.au/first-aid-self-care/tooth-
anatomy) shows a drawing of a healthy tooth cut in half lengthways, which shows the
layers of the tooth and its internal structure, as well as how the tooth relates to the gum and
surrounding jaw bone.
