A quantitative calibration strategy for reproducible extrusion-based bioprinting using gelatin methacryloyl hydrogels

Abstract

[Abstract] Extrusion-based three-dimensional bioprinting remains limited by the absence of standardized methods to define the pressure conditions required for stable hydrogel flow. As a result, most workflows still rely on empirical tuning, which compromises reproducibility, structural fidelity, and interlaboratory comparability. Addressing this gap requires quantitative tools capable of identifying the minimum pressure for extrusion and the pressure range in which continuous, defect-free flow is maintained. This work presents a modular characterization platform integrating real-time pressure sensing, together with nozzle temperature regulation and environmental monitoring (temperature, humidity, and carbon dioxide) to ensure controlled and reproducible extrusion conditions. Using 10% gelatin methacryloyl, force–displacement curves revealed a stabilization pressure of 165 kPa, associated with continuous extrusion and minimal geometric deviation, and bounded by experimentally validated under-extrusion (155 kPa) and over-extrusion (185 kPa) conditions. Bioprinting tests confirmed that operating within this stabilization zone improves filament uniformity, print fidelity, and dimensional accuracy compared with under- and over-extrusion regimes. Quantitative metrics, including deflection analysis, printability parameter, void–area similarity, and structural similarity index, demonstrated superior reproducibility at the stabilization pressure. Biological validation using MCF-7 cells showed that 165 kPa preserved high viability (97.9%), whereas extrusion at 185 kPa reduced survival to 88.6%, confirming the sensitivity of cell integrity to excess shear stress. Together, these findings establish a sensor-driven calibration strategy that replaces trial-and-error parameter selection with quantitative and reproducible pre-print optimization. The device is compatible with commercial bioprinters and provides a practical framework for improving process standardization, structural fidelity, and biological safety in extrusion-based bioprinting. The platform is conceived as an independent, modular device for experimental calibration of extrusion parameters prior to bioprinting.