From my vantage point at 3Diligent, a rapid manufacturing
service provider that helps companies with their 3D printing
projects, one industry in which additive manufacturing
applications are especially prevalent and gaining acceptance
is the medical field.
Since 3D printing builds objects one voxel (3D pixel) at
a time, it is uniquely suited to construct complex organic
shapes that are implausible or impossible with traditional
manufacturing techniques. These shapes can, for instance,
contain intricate internal geometries and custom-tailored
porosity to mimic different bone densities. Moreover, this
complexity is available virtually free of charge.
Recognizing the value proposition and economics are
compelling for the medical community, are the currently
available materials sufficient to meet market demands?
Which materials are currently available? Which are still to
come? This update on the state of the 3D printing materials
market will show that there are more available now than is
generally perceived, and more are rapidly on the way.
AQUEOUS SOLUTIONS/BIO INKS
Aqueous solutions – sometimes referred to as bio inks
within the 3D-printing domain - include Poly (2-hydroxyethyl
methacrylate) (pHEMA) and Polyethylene (glycol) Diacrylate
(PEGDA). However, this is an area of vast investment and
research with many promising new hydrogel materials in
These are commonly printed using pneumatic or hydraulic
extrusion. This can be at room temperature to preserve living
cells, for instance, or through a heated nozzle. Aqueous
solutions can also be “indirectly” 3D printed, in the sense
that part patterns can sometimes be fabricated with high-
accuracy wax or resin printers, and those are in turn used to
create transparent molds. The aqueous solutions can then be
poured into the transparent mold and cast, typically with the
use of UV light.
Applications for these solutions are wide, as the
material range is virtually unlimited, so long as the active
agent/material can be carried in water. In the case of
reconstructive surgery, bone material can be carried within a
hydrogel and printed onto bone. The deposited material can
act as a binding agent between bone fragments, facilitating
the ingrowth of bone to reconnect previously shattered bone.
In the world of polymers, the number of medical materials
available is expanding rapidly.
Low melting point polymers are often printed using
extrusion technologies – otherwise referred to by brand
names like Fused Deposition Modeling (FDM) or Fused
Filament Fabrication (FFF). The most popular biodegradable
polymer is Polylactic Acid (PLA). It is the default material for
many desktop FFF printers. Due to that position in the market,
it has been affordably printed on a wide variety of machines,
not just extrusion printers but also laser sintering printers, for
a number of applications like biodegradable stents.
Other popular low-melting temperature polymers include
Polycaprolactone (PCL), a biodegradable polyester, which
is used for things like skin grafts due to its ability to facilitate
cell growth, and Polycylcolide (or polyglycolic acid) (PGA).
There is still a good deal of research to be done with
respect to low- temperature polymers. However, as Roger
Narayan, Special ASME Fellow to America Makes notes,
what has not yet been offered by manufacturers to this point
is biodegradable polymers with several different molecular
weights. For example, the ability to print materials with
Industrial additive manufacturing has emerged from the trough of disillusionment and is now experiencing a renaissance of sorts. This is
in good part due to a proliferation of industrial
printer manufacturers, many of whom are bringing
new technologies and more open approaches to
materials and parameters to the market.
Figure 1. Researchers from Harvard utilize extruded bio inks to
print various organic shapes, including this proximal tubule, a critical
component of kidney nephrons. Image Credit: The Lewis Lab