Biomedical Engineering Reference
In-Depth Information
interest for the fabrication of biomaterials. Such layers play important roles in
biological mineralization by controlling the size, orientation, and morphology of
inorganic crystals at the surface of the protein layer. This system is broadly studied
and widely believed to serve as the platform of choice to develop a variety of bio-
logical technologies.
Rapid prototyping
is the name given to a host of related technologies that are
used to fabricate physical objects directly from digital data sources. These meth-
ods are unique in that they add and bond materials in layers to form objects. Such
systems are also called solid freeform fabrication, layered manufacturing, stere-
olithography, selective laser sintering, fused deposition modeling, laminated object
manufacturing, inkjet-based systems, and 3D printing. These names are often used
as synonyms for the entire field of rapid prototyping; however, each of these tech-
nologies has its strengths and weaknesses. The general process begins with devel-
oping a computer-generated model using computer-aided design (CAD) software.
Potentially, one could use digital images obtained by computer tomography or
magnetic resonance imaging (discussed in Chapter 9) scans to create a customized
CAD model. This CAD model is then expressed as a series of cross-sectional layers.
The data is then implemented to the rapid prototyping machine, which builds the
desired object a layer at a time, similar to laser printing (Figure 6.12). The material
could be self-adhesive or one could use a small quantity of an adhesive. Once one
layer is completely traced, it is lowered by a small distance and a second layer is
traced right on top of the first. The adhesive property of the materials used cause
layers to bond to one another and eventually form a complete, three-dimensional
object after many such layers are formed. Objects can be made from multiple ma-
terials as composites, or materials can even be varied in a controlled fashion at any
location in an object. Although objects can be formed with any geometric com-
plexity or intricacy without the need for elaborate final assembly, few limitations
include manipulating the porosity of the scaffold, and the type of material that can
be printed.
Figure 6.12
Microstructure of scaffolds formed using by rapid prototyping and chitosan solution.
