3D Printing\nof Silicone Organogel Elastomers for Structured\nSoft Biomaterials

Creating customizable soft medical implants and devices\ntailored\nto patient-specific anatomy represents a significant challenge in\nhealthcare, requiring 3D-printable materials with viscoelastic properties\nsimilar to those of natural tissue, high adaptability, and biocompatibility.\nHere, we develop a family of silicone organogel inks for 3D printing\nof tunable soft biomaterials via direct ink writing (DIW). We have\ndeveloped a set of ink formulations comprising photo-cross-linkable\nsilicone polymers, silicone oil, and fumed silica nanoparticles to\nmodify the rheological behavior of the inks, optimize their printability,\nand control the viscoelastic properties of the printed organogel materials.\nThe formulation approach decouples ink viscosity and shear-thinning\nbehavior from the properties of the printed organogel materials, yielding\nsoft elastomeric materials spanning 3 orders of magnitude in moduli.\nThese organogel inks were used in multimaterial DIW to print soft-structured\nmaterials with nonlinear behavior, leveraging graded spatial heterogeneity\nto introduce stress dissipation and out-of-plane deformation mechanisms.\nThe biocompatibility of these organogel materials was analyzed through\na variety of cytotoxicity assays with human dermal fibroblasts, showing\nno significant toxicity, even in formulations with high silicone oil\ncontent. Due to their wide tunability, biocompatibility, and easy\nprintability, these silicone organogel materials show great potential\nfor 3D printing customizable soft devices useful in many applications,\nincluding patient-specific implants, prosthetics, wearable devices,\nmedical phantoms, soft robotics, and medical devices.