Influence of process parameters on shape fidelity in extrusion-based bioprinting: a rheological perspective

Extrusion-based bioprinting enables the controlled deposition of hydrogels, which are crucial for cell viability in bioengineering. In this context, shape fidelity—defined as the correspondence between the printed construct and its digital model—emerges as a critical performance metric. This study systematically investigates the influence of inlet pressure, printing speed, and temperature on shape fidelity for two hydrogels: a natural alginate/cellulose blend and a synthetic PEG-based material. Comprehensive rheological characterization was performed to assess viscoelastic behavior, and a Shape Fidelity Index (SFI) was applied to quantify dimensional accuracy across 24 parameter configurations. The synthetic hydrogel exhibited lower sensitivity to parameter variations, ensuring robust processability. Conversely, while the natural hydrogel was more sensitive to operating conditions, it achieved the highest absolute SFI values within the investigated experimental campaign. This superior performance is attributed to its distinct rheological behavior, characterized by a Sisko-type flow, which enhanced filament shape retention. These findings underscore the importance of integrated rheological analysis and parameter selection for improving the fabrication of high-resolution biomedical structures.