Biomedical Engineering Reference
In-Depth Information
an intended biological purpose upon matrix degradation. Examples of this type of
application will be dealt with Sect.
13.4.1
.
13.3.6
Fabrication Techniques
Knowledge from physical chemistry, materials science, process engineering, laser
technology and recent innovative technological techniques has been used for the
construction of scaffolds. Traditional methods of fabricating scaffolds include
sol-
vent-casting and particulate (salt or ice crystals)-leaching, gas foaming, thermally
induced phase separation (TIPS), fiber meshes/fiber bonding, melt moulding, emul-
sion freeze drying, solution casting and freeze drying
. These methods create isotrop-
ically distributed voids and connecting pores, much like in a sponge, but have
been largely unsuccessful in controlling the internal architecture to a high degree
of accuracy or homogeneity [
405
,
420
].
Currently, rapid prototyping techniques or SFF fabrication technologies are used
with the aim of creating scaffolds with identical internal architectures so as to
facilitate the mechanobiological characteristics of the construct. These technolo-
gies include stereolithography, selective laser sintering, fused deposition modeling
and three-dimensional printing (see Chap.
7
and [
412
,
420
]). Representative exam-
ples of both traditional and solid free-form (SFF) fabrication techniques are shown
in Figs.
13.4
and
13.5
, respectively.
In attempting to mimic the ECM, composed largely of collagen fibers in the
range of 50-500 nm in diameter, considerable effort has been devoted in producing
Fig. 13.4
SEM photograph of a poly-lactic-glycolic acid copolymer foamy scaffold with almost
spherical pores, 280-315
m in diameter, produced by leaching of paraffin spheres. Smaller
surface and porosity features can also be seen. Adapted from http://vascuplug.teltow.gkss.de
