Suspended bioprinting with in-situ elasticity monitoring using the assessment of shear wave phase velocity

Suspended bioprinting has recently emerged as a promising alternative for fabricating intricate tissue-engineered scaffolds by enabling the precise deposition of low-viscosity bioink within a support bath, overcoming the limitations of conventional bioprinting methods. However, the dynamic monitoring of scaffold mechanical properties during fabrication remains a significant challenge. This study introduces a novel approach for suspended bioprinting with in-situ elasticity monitoring (SBEM), leveraging ultrasound shear wave elastography to nondestructively and dynamically assess the elastic properties of the bioprinted constructs. Using a custom-designed 3D bioprinting system, alginate and gelatin methacrylate (GelMA) scaffolds with varying cellulose nanocrystal concentrations and diverse geometries were fabricated in a Carbopol support bath. Phase velocities of shear waves were tracked and analyzed to estimate the storage moduli, validated against conventional rheometry. The SBEM approach demonstrated high temporal resolution in monitoring of elasticity changes during photocrosslinking. Additionally, cell-laden GelMA scaffolds maintained high cell viability after the measurement, confirming the biocompatibility of the technique. This approach addresses critical limitations in real-time mechanical monitoring, offering a scalable, nondestructive solution for optimizing scaffold properties during suspended bioprinting. The SBEM method holds significant potential to advance precision and quality control in tissue engineering applications.