A versatile and high-resolution hydrogel platform for volumetric additive manufacturing based on poly(ethylene glycol) diacrylate and alginate blends

Volumetric additive manufacturing (VAM) has emerged as a potent method for fabricating complex structures out of soft materials such as hydrogels. In this study, we developed a low-cost photopolymer platform based on low molecular weight poly (ethylene glycol) diacrylate (PEGDA) and alginate (Alg) blends which reduces material costs ~1000x. By adding non-crosslinked 0.5 wt.% of Alg to these 5, 10, or 15 wt.% PEGDA precursor solutions, we raised the viscosity from <1 mPa*s to 50 mPa*s, which enables VAM of low molecular weight PEGDA. The fabricated hydrogels have customizable mechanical properties, ranging from 14 ± 4 kPa to 90 ± 24 kPa, and 289 ± 121 kPa and correspond to equilibrium water contents of 96.8 ± 0.3%, 91.2% ± 0.8% and 84.1% ± 0.9%. The printed structures had minimum feature sizes ranging between 56 ± 9 μm for 5% PEGDA + 0.5 wt.% Alg, 47 ± 12 μm for 10% PEGDA + 0.5 wt.% Alg, and 39 ± 7 μm for 15% PEGDA + 0.5 wt.% Alg. Additionally, these materials are printable into designs with internal voids, unsupported struts, and interlocked features. Overall, this work establishes a low cost, mechanically tunable hydrogel platform for high resolution VAM which can improve accessibility and adoption.