Table 1.
Comparison of different 4D bioprinting technologies.
| 4D bioprinting technologies |
|||||
|---|---|---|---|---|---|
| MEB | Inkjet | SLA | DLP | LAB | |
| Ink/bioink viscosity | 1 to > 107 mPa s [56,57] | 3–30 mPa s [52] | 3–300 mPa s [58,59] | 1–200 mPa s [60,61] | 1–300 mPa s [62,63] |
| Cell density | 108 cells/ml, cell spheroids, organoids [49,51,64,65] | 106 cells/ml [66,67] | > 106 cells/ml [68,69] | 106 to108 cells/ml [61,70] | 108 cells/ml [62] |
| Cell viability | 70–95% [37,71] | >85% [67,72,73] | >75% [68,69] | >75% [74] | >85% [63,75] |
| Nozzle diameter | 200 μm to mm scale | 20–150 μm | Nozzle free | Nozzle free | Nozzle free |
| Resolution | 200 μm to mm scale | 50–300 μm | 20–80 μm | <150 μm | <150 μm |
| Printing speed | Slow | Fast | Medium to fast | Fast | Slow |
| Typical materials | Shape memory polymers, hydrogels, and composites (e.g., AlgMA [37,40], MC/alginate [42,76], cellulose nanofiber/NIPAM [35]) | Hydrogels (e.g., GelMA [73]) | Photopolymers (e.g., soybean oil epoxidized acrylate [77]) | Photopolymers (e.g., silk fibroin [70], GelMA/PEGDA [74]) | Hydrogels (e.g., collagen [75]) |
| External stimuli | Humidity [37,40], heat [78,79], and light [80,81] | Humidity [82] | Humidity, temperature [77] | Humidity [70,74] | Patterned fibroblasts [75] |
Abbreviation: AlgMA, methacrylate alginate; MC, methylcellulose; NIPAM, N-isopropylacrylamide; GelMA, gelatin methacryloyl; PEGDA, poly(ethylene glycol) diacrylate.