PVA Cryo-microgels for rapidly fabricating solid soft tissue phantoms using embedded 3D-Printing

Embedded 3D-printing of polymers and hydrogel precursors enables the manufacturing of soft tissue phantom models that mimic the heterogeneous complexities of native tissue. Recently, we have demonstrated that poly(vinyl alcohol) (PVA) polymers can be functionalized with a methacrylate group to enable chemical crosslinking and demonstrated their application as a polymer ink to fabricate a 15% scale model of a human brain. However, scaling the phantom model up to full size with 100% infill while maintaining micrometre-sized features extends the printing time from a few hours to several days, resulting in polymer diffusion and loss of feature fidelity. To reduce manufacturing times and enable the rapid fabrication of phantom models, we design microgel particles through the mechanical agitation of PVA cryogels to act as a support bath for 3D-printing and as the polymer infill of 3D-printed phantom structures to drastically reduce the printing time of full-scale soft tissue phantoms. After fabricating a thin-walled phantom model using covalently crosslinkable polymers, the phantom is subjected to freeze-thaw cycles to physically crosslink the PVA cryo-microgel interior, resulting in a solid phantom with 100% infill.