3D PRINTING AND NANOMANUFACTURING - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 26

2.2 3D PRINTING AND NANOMANUFACTURING TECHNIQUES
With the development of computer-aided design (CAD) technology and automation techniques, rapid and
automatic additive manufacturing (AM) systems have advanced for the fabrication of complicated 3D struc-
tures over the past few decades. In general, the 3D model to be fabricated is first designed using CAD mod-
eling software, such as Solidworks and AutoCAD. Generated 3D CAD data are then processed and sliced
into layers of equal thickness, each of which is the cross-section of the 3D model at a certain level. Sliced
data are imported into the AM system to fabricate 3D objects layer-by-layer. In this fabrication process, lay-
ers are cumulated vertically and fused to form the final physical object ( Chua et al . , 2010; Tan et al . , 2005 ).
2.2.1 SELECTIVE LASER SINTERING
Selective laser sintering (SLS) ( Tan et al . , 2005; Duan et al . , 2010; Kanczler et al . , 2009; Liu et al . , 2013;
Williams et al . , 2005 ) was developed and patented in the mid-1980s ( Deckard, 1989 ). This technique uses
a laser beam (usually CO 2 laser) to sinter slices of powdered materials via repeated process of spreading
layers and selectively heating and fusing each powdered layer in order to fabricate three-dimensional struc-
tures. Thus, the objects are formed layer-by-layer from sliced CAD data. During the process, the unmelted
powders act as the support for the fused object. Figure 2.1 represents the selective laser sintering process.
FIGURE 2.1
A schematic layout of the SLS process ( Tan et al . , 2005 ).