Biomedical Engineering Reference
In-Depth Information
Table 9.4
Hydrogel materials explored in printer-based systems.
Printer-based systems
Hydrogel material
Cell encapsulation
References
3DP™
Starch/cellulose/dextrose
×
[
220,
221
]
Starch/cellulose fi bre/sucrose/
maltodextrin
×
[
234
]
Corn starch/gelatine/dextran
×
[
221
]
Starch/polyurethanes/PEG
×
[
220
]
PEO/PCL
×
[
225
]
PLLGA/Pluronic® F127
×
[
228
]
HA/cellulose/starch
×
[
233
]
Inkjet printing
Peg/Collagen/Pdl
×
[
226
]
Collagen
√
[
235
]
Alginate/Gelatin
√
[
223
]
Fibrin
√
[
227,
229
]
In 3DP, control over the geometry is realized by two distinct issues: the minimum
attainable feature size and the variability of part dimensions [
217
] . Both depend
strongly on the binder droplet-powder particle interactions. Factors controlling the
interaction of powder and binder include: powder material, powder surface treat-
ment, powder size and size distribution, powder shape, powder packing density,
binder material, binder viscosity, binder surface tension, droplet size, droplet veloc-
ity, temperature of the powder and binder and ambient temperature [
217
] . Factors
that determine the final object dimensions are: local and accumulative accuracy of
deposited layer thickness, accuracy of drop placement, reproducibility of the spread
of the printed droplets and reproducibility of the dimensional changes that accom-
pany binder cure. Sometimes, resolution of the machine is mentioned. Resolution in
this context refers to the smallest pores and the thinnest material structures that are
obtainable with the equipment [
217
] .
Inkjet printing
. This printer-based subclass comprises all liquid-phase inkjet tech-
nologies. It can vary from set-ups similar to the 3DP™ system in which the powder
bed is replaced by a liquid hydrogel precursor [
223
], or systems that use direct ink-
jet writing [
12,
224
]. In the case of direct inkjet writing, the construct is build up by
the deposited liquid itself.
9.3.3.2
Current Limitations and Hydrogel Feasibility
for Printer-Based Systems
Printer-based systems can perhaps be regarded as the least hydrogel/cell suitable of
the systems that allow hydrogel processing. Tables
9.4
and
9.5
, summarize the
hydrogel feasibility respectively limitations towards hydrogel manufacturing. Wu
et al. [
225
] described the use of polyethylene oxide (PEO) and poly-e -caprolactone
(PCL) as matrix materials and a 20 % PCL-LPS/chloroform binder solution to cre-
ate a 3D device for controlled drug release. Top and bottom layer of the tabular
device was made out of slowly degrading PCL, while the interior layers were
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