Page 269 - IJB-9-5

International Journal of Bioprinting

References [20-24] [25-32] [23,30,33,35,36] [30,32,37,40] to meet different printing requirements, such as embedded
printing, co-axial printing, multi- or single-nozzle multi-
material printing, and continuous chaotic printing . For
[26]
example, single-nozzle multi-material printing allows the
synchronized delivery of different bioinks with an array
of nozzles to fabricate the product with heterogeneous
materials and gradient hierarchical structures . In addition,
[27]
the fabrication of multi-material core-shell structures that
mimic anatomical tissues can be easily achieved by co-axial
printing . The nozzle size can be adjusted by computer to
[28]
[29]
compared with other 3D printing technologies, the printing
resolution of the EBP is lower, resulting in poorer accuracy
of cell organization . The reduction in nozzle diameter
Disadvantages • Easy nozzle clogging • Limited bioink viscosity • Low cell density (<10 6 cells/mL) • Low cell viability (40%–80%) • Moderate resolution • Low cell density (<10 6 cells/mL) • High cost • Complex control system • Only support liquid photosensitive materials realize the control of the printing resolution . However,
[30]
may place greater shear stress on the cells, resulting in a
decrease in cell viability . Despite such drawbacks as
[31]
limited resolution and lower cell activity, EBP is still widely
applied due to fast printing speed, ease of implementation,
and support for a wide range of bioinks, especially bioinks
with high cell density or high viscosity .
[32]

2.3. Laser-assisted printing
• High cell viability (75%–95%) • High print resolution • Support multi-material • High bioink viscosity • High cell density (>10 8 cells/mL) • Suitable for multi-material and various • High cell viability (>95%) • High bioink viscosity • High print resolution • High cell viability (>85%) • High print resolution approach that avoids technical problems associated with
Laser-assisted printing (LAP) is a nozzle-free printing
the printhead, such as nozzle clogging. LAP is composed
of a pulsed laser source, a donor slide, and a receiver slide
Table 1. Comparison of different 3D printing techniques in cartilage tissue engineering
(Figure 1C) . The donor slide consists of three layers from
[33]
Advantages • Low cost printing demands top to bottom, which are made of transparent glass, metal,
and bioink, respectively. The working principle of LAP is
derived from laser-induced forward transfer technology,
which was introduced over 30 years ago . The ultraviolet
[34]
(UV) light from a pulsed laser source projects onto the
energy-absorbing layer (metal layer) of the donor slide
and causes local vaporization. The vaporization-induced
bubbles push the bioink layer on the lower part of the
donor slide to form droplets, which are deposited on the
receiving substrate and quickly crosslinked . In the non-
[35]
by adjusting the thickness of the metal film . Moreover,
[36]
cells are free from either thermal or mechanical stress, thus
Sub-category • Thermal inkjet printing • Piezoelectric inkjet printing • Acoustic droplet ejection • Embedded printing • Co-axial printing • Multi- or single-nozzle multi-material printing • Continuous chaotic printing • Stereolithography • Digital light processing contact printing process, cell viability can be protected
maintaining a relatively high cell activity (>95%) . By
[23]
adjusting the parameters of the laser pulse, high-precision
printing of bioinks with different viscosities can be
achieved. However, compared with nozzle-based printing
-
technology, the high cost and complex control system limit
the application of LAP .
[30]
3D printing techniques Inkjet printing Extrusion-based printing Laser-assisted printing Vat photopolymerization 2.4. Vat photopolymerization
Vat photopolymerization (VPP) 3D printing includes
stereolithography (Figure 1D) and digital light processing
(Figure 1E) . The principle of stereolithography is that
[37]
the liquid photosensitive bioink is photopolymerized in
a vat under exposure to UV light. After the computer-

Volume 9 Issue 5 (2023) 261 https://doi.org/10.18063/ijb.761