Biomedical Engineering Reference
In-Depth Information
such as manual intervention, inconsistent and inflexible process-
ing procedures, use of cytotoxic solvent, and shape and dimension
limitations for scaffolds produced, have restricted their scope of
application. 23 Therefore, designed manufacturing techniques devel-
oped in recent years are promising alternative scaffold fabrication
techniquesforachievingextensiveanddetailedcontroloverscaffold
architecture and hence properties.
45.2 Application of Rapid Prototyping Technologies to
Scaffold Fabrication
RP is a common name for a group of technologies that can gen-
erate a physical model directly from computer-aided design (CAD)
data in a layer-by-layer manner, and each layer is the shape of the
cross-section of the model at a specific level. 23 The data used to
design and fabricate tissue engineering scaffolds is usually based
on CAD systems, computer-based medical imaging technologies, or
other computer-based technologies. 24 , 25 In a typical RP operation,
computer-based data is first converted to an STL-type file format,
“STL” being derived from “stereolithography,” which is the oldest
RP technology. Then the computer-generated 2D layers are created
for building a solid model, starting from the bottom and proceed-
ing upward. Each layer is glued or otherwise bonded to the pre-
vious layer, thus producing a solid model of the object according
to the design. The advantages of RP techniques over conventional
scaffold production methods include, but are not limited to, achiev-
ing well-defined external and internal architectures of the scaffolds,
computer-controlled manufacturing processes, and high accuracy
and reproducibility.
On the basis of their working principles, RP techniques can
be divided into several categories: laser polymerization-based
techniques, such as stereolithography apparatus (SLA); nozzle
deposition-based techniques, such as fused deposition modeling
(FDM); and powder-based techniques, such as 3D printing and
SLS. 26 , 27 The techniques in each category are suitable for a specific
form of raw materials and have their own advantages and disad-
vantages. More and newer RP techniques, such as low-temperature
 
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