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Zhang, et al.
ceramics, and polymers. These implants are used technology can also quickly print photosensitive
to replace or repair the injuries in vivo. First, the resin materials. These resin materials have been
shapes of the implants are well-matched with the widely used as a filling materials in stomatology
injury parts. Then, the printed microstructure can due to the characteristics of low viscosity, curing
guide the regeneration of injured tissues. and shrinking, fast processing rate, small swelling,
and high wet strength .
[35]
3.2.1 Biodegradable implants
Biodegradable implants refer to a series of medical 3.3 Functionalized devices
implants that can be gradually degraded by the Besides satisfying shapes and microstructures
human body with the change of time and other of DLP printed 3D models and implants, it can
conditions after implantation and finally replaced add specific functions to medical devices. These
by human original tissues. Many biodegradable devices take the fixability to combine materials
materials, such as alginate, cellulose, extracellular and structures to achieve their functions. Due to
matrix (ECM), and collagen, have been developed the efficiency and high accuracy of DLP printing,
and applied in DLP 3D printing. Christopher it only takes a short time to fabricate medical
et al. used the DMD device that can print in devices with powerful functions.
micron scale to obtain nerve conduits with In 2014, Gou et al. loaded the printed hydrogel
parallel microchannels (Figure 2D i). The light with polydiacetylene (PDA) nanoparticles to
is reflected by the 20 μm size mirrors of the construct a detoxification device (Figure 2F).
device. This translates the 2D image into a 3D The lobule-like microstructures allow efficient
microstructure that is identical to the micron array contact between toxins and the 3D devices. At
of mirrors. The microstructure can guide Schwann the same time, detoxification particles in the
cell-directed migration. Tao et al. created similar hydrogel can trap and attract toxins while sensing
nerve conduits encapsulating nanoparticles. The them. It turns out that the printed detoxification
drugs loaded in nanoparticles can further improve hydrogel device can effectively remove certain
the regeneration of injured nerve . For treating toxins from aqueous solutions . The combination
[38]
[8]
different injury sites, Zhu et al. have utilized this of PDA nanoparticles and 3D printed hydrogels
technique to create a series of nerve conduits, such not only act as a detoxification device but also a
as conduits with microchannels and even bionic toxin sensor in solutions. When the nanoparticles
conduits that are beneficial to nerve repair in bind to the toxin, the ordered π-conjugated chain
humans (Figure 2D ii) . structure on the particle surface is disrupted,
[34]
3.2.2 Non-biodegradable implants triggering a fluorescent radiation reaction that
makes it easy to detect the presence of the
DLP 3D printed implants play an important role toxin. Zhu et al. printed swimming microfish
in stomatology, brain surgery, ent (ear, nose encapsulated PDA, iron oxide, and platinum
and throat), thoracic surgery, and other surgical nanoparticles (Figure 2G). The microfish can be
operations. Reham et al. reported that they chemically powered and magnetically guided.
used DLP technology to fabricate a customized They took the fluorescence intensity change of
zirconia implant and evaluated its related physical PDA as an indicator to evaluate the detoxification
properties (Figure 2E). In this study, they efficiency of hydrogels and the concentration of
evaluated the precision size, surface morphology, toxins in solution . Recently, a 3D paper-based
[36]
and physical properties of printed zirconia microfluidics analysis device (3D-μPAD) has
implants . The results show that this printed been reported for in vitro diagnosis (Figure 2H).
[39]
custom implant has a precision size similar to the The 3D-μPAD is produced by a DLP 3D printer
reference model and competitive bending strength using a material called photoluminescent liquid
(943 MPa), which can be compared with grinding resin, which is printed on both sides of the paper
zirconia (800–1000 MPa). In addition, DLP in one go, with no additional assembly required.

International Journal of Bioprinting (2020)–Volume 6, Issue 1 17