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International Journal of Bioprinting 3D-printed scaffolds for TMJ fibrocartilage regeneration

Figure 1. Schematic diagram of different 3D printing techniques supporting bioink. (A) Inkjet printing. (B) Extrusion-based printing (EBP). (from
[19]
ref. licensed under Creative Commons Attribution license). (C) Laser-assisted printing (LAP). Reproduced with permission from Ravanbakhsh H,
[41]
[37]
Karamzadeh V, Bao G, et al., Adv Mater, Copyright © 1999-2023 John Wiley & Sons . (D) Stereolithography. (E) Digital light processing. (from ref.
licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 license).
the biological properties of the artificial scaffold, which then expand and push the bioink out of the nozzle to form
is then transplanted to the tissue defect site in vivo. droplets . The bioink used for thermal inkjet printing
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Compared with the traditional 3D printing techniques, must be thermally stable, which limits the choice of bioink.
some 3D printing techniques supporting bioink have Compared with thermal inkjet printing, piezoelectric inkjet
greater potential in cartilage tissue engineering and have printing generates a pressure pulse inside the nozzle by a
gained growing popularity in recent years, and some of piezoelectric element, thus avoiding potential adverse effects
them are introduced below (Table 1). on cells in the bioink from the thermal stress. However, it
is difficult for the thermal/piezoelectric inkjet system to
2.1. Inkjet printing print with bioinks with high viscosity or high cell density
Inkjet printing technology is characterized by low-cost, high due to nozzle clogging . In recent years, the acoustic
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printing speed, relatively high cell viability, and combined droplet ejection technology has been developed, which
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use of bioinks with different properties (Figure 1A) . forms droplets by acoustic energy and has the advantage of
During the electronically controlled printing process, the protecting the printheads from clogging by manipulating
bioink is squeezed into micron-scale droplets at the printer the droplet size .
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head by a thermal or piezoelectric actuator. The droplets
of a controllable size are sprayed onto the substrate, and 2.2. Extrusion-based printing
the tailored 3D structure is generated by layer-by-layer The principle of the extrusion-based printing (EBP)
deposition of bioink . The thermal inkjet system and technique is that the pneumatic, piston, or screw-driven
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the piezoelectric inkjet system differ in their operating device generates continuous pressure to extrude the bioink
principles and characteristics. In a thermal inkjet system, from the nozzle to form filaments, which are deposited
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a tiny heating element near the nozzle rapidly heats up to on the platform to form a 3D structure (Figure 1B) .
200–300°C in a few microseconds to form bubbles, which Several variations of EBP strategies have been developed

Volume 9 Issue 5 (2023) 260 https://doi.org/10.18063/ijb.761