Biomedical Engineering Reference
In-Depth Information
manufacturing enables to create practically any shapes or geomet-
ric features, including overhangs and complex internal structures.
The method is most suitable for custom-made production. There-
fore,layermanufacturingissuperiortotheothertwo3Dfabrication
methods in manufacturing medical implants. 19
Withinlayermanufacturing,thereareseveralmajorsubmethods
that have distinct features, using different materials. 15 They include
stereolithography, fused deposition modeling, selective laser sin-
tering, and inkjet printing. The current stereolithography method
uses photosensitive resins and photoinitiators that are usually
not biocompatible or biodegradable. 20 Furthermore, the method
produces radicals that are toxic to human bodies. The fused depo-
sition modeling method uses thermoplastics that are usually not
biocompatible or biodegradable and require a support structure in
somecases. 21 Selectivelasersinteringusesthermoplasticresinsand
metalpowdersathightemperature,whichcausessizecontraction. 22
By the inkjet printing technology, in contrast, biocompatible and
biodegradablematerialscanbeprocessedatroomtemperature,and
porous scaffolds with controlled internal structures with high reso-
lution can be manufactured. 23 As we already argued, calcium phos-
phates have a great advantage as biomaterials for artificial bones
over metals and polymers because of their excellent combination of
good material properties. 9 Thus, among the different submethods
of layer manufacturing, inkjet printing seems to have the greatest
potential to directly fabricate calcium phosphate materials.
29.4 Inkjet Printing Technology
In inkjet printing, powder material is first spread by a roller onto
a thin sheet. Then, an inkhead prints a curing solution and draw
pictures on the sheet. The thin sheet of the powder material then
becomes solidified where the curing solution is printed. In the next
step, another thin sheet of the powder material is newly spread
on top of the solidified layer, and the process is repeated until the
final shape is created. 23 Despite efforts by a number of researchers,
there has been no success in directly manufacturing clinically use-
ful custom-made implants from calcium phosphates by the inkjet
 
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