In-situ quality monitoring during embedded bioprinting using integrated microscopy and classical computer vision

Abstract

Embedded bioprinting into support hydrogels enables controlled extrusion of low viscosity bioinks into complex 3D structures with high-resolution features. Granular hydrogels, formed through packing of hydrogel microparticles, are increasingly employed as support materials due to their shear-thinning and self-healing properties that are essential for the embedded bioprinting process. Despite the widespread use of granular support hydrogels for embedded bioprinting, their general design criteria such as the optimal particle morphology, size, and packing density have not been established. Here, we developed granular support hydrogels with varied particle morphologies and packing densities, to explore how these parameters can influence rheological behaviour and the embedded bioprinting process. Interestingly, lower viscosity support hydrogels with a higher yield point, formulated from particles with irregular morphologies that increased particle-particle interactions, were found to improve print quality outcomes. In particular, we observed these formulations improved extrusion consistency during complex print paths and reduced disruption of adjacent filaments during successive print paths. These results improve our understanding of particle-particle interactions in granular support hydrogels during embedded bioprinting, and can be used to inform the design of future support hydrogel compositions.

A dive into the bath: embedded 3D bioprinting of freeform in vitro models

“…Among all types, granular hydrogels have been extensively used in embedding printing due to their easy production methods, in addition to its self-recovery and shear-thinning properties. 53 Their rheological behavior can be easily tuned by engineering the physical and chemical nature of forming microparticles, their packing densities or by using mixed types and sizes of microparticles. 53–55 One of the most explored support baths for producing in vitro models is the well-known freeform reversible embedding of suspended hydrogels (FRESH) system (Fig.…”

“…53 Their rheological behavior can be easily tuned by engineering the physical and chemical nature of forming microparticles, their packing densities or by using mixed types and sizes of microparticles. 53–55 One of the most explored support baths for producing in vitro models is the well-known freeform reversible embedding of suspended hydrogels (FRESH) system (Fig. 1A and B), which is originally based on gelatin microparticles.…”