Table 1.

Characteristics of 3D bioprinting processes. Reprinted with permission under open access from Li et al. [127].

Types of Bioprinters	Biomaterials	Cell Viability/Resolution	Bioprinting Speed	Cost	Advantages	Disadvantages
Inkjet-based bioprinting	Low-viscosity suspension of living cells; biomolecules; growth factors	~90% 20–100 μm	Fast (<10,000 droplets/s)	Low	Wide availability; low cost; high resolution; high printing speed; ability to introduce concentration gradients in 3D constructs	Poor vertical structure clogging characteristics; thermal and mechanical stress to cells; limited printable materials (liquid only)
Pressure-assisted bioprinting	Hydrogel; melt; cells; proteins and ceramic materials; solutions, pastes, or dispersions of low to high viscosity; Poly Lactic-co-Glycolic Acid (PLGA); tricalcium phosphate (TCP); collagen and chitosan; collagenalginate-silica composites coated with HA; and agarose with gelatin	40–80% 200 μm	Slow	Medium	Numerous materials that can be printed with any dimensions; mild conditions (room temperature); use of cellular spheroids; direct incorporation of cells; and homogenous distribution of cells	Limited mechanical stiffness; critical timing of gelation time; specific matching of the densities of the material and the liquid medium to preserve shapes; low resolution and viability
Laser-assisted bioprinting	Hydrogel, media, cells, proteins and ceramic materials of varying viscosity	>95% >20 μm	Medium	High	Nozzle-free, noncontact process; cells are printed with high activity and high resolution; high control of ink droplets and precise delivery	High cost; cumbersome and time consuming; requires a metal film and thus is subject to metallic particle contamination
Stereolithography	Light-sensitive polymer materials; curable acrylics and epoxies	>90% ~1.2–200 μm	Fast (<40,000 mm/s)	Low	Solid freeform and nozzle-free technology; highest fabrication accuracy; compatibility with an increasing number of materials; light-sensitive hydrogels can be printed layer-by-layer	Applicable to photopolymers only; lack of biocompatible and biodegradable polymers; harmful effects from residual toxic photo-curing reagents; possibility of harm to DNA and human skin by ultraviolet (UV)