Abstract

FRESH 3D Printing of Liquid and Soft Materials: New Applications From Regenerative Medicine to Wearable Sensing

Adam Feinberg, Associate Professor, Carnegie Mellon University

Over the past decade, 3D bioprinting has rapidly expanded from a niche technology and in to a versatile platform for fabricating tissues with complex geometries and features ranging from the cellular to organ length scales. Recent advances include engineering the 3D cell microenvironment, hierarchical vascular networks in thick tissue constructs and biodegradable tissue scaffolds implanted in animal models and human patients. However, the range of additive manufacturing technologies currently used each has distinct advantages and disadvantages, and specifically it is critical to understand how the resolution of these different approaches dictate structure and function of the engineered tissue constructs. Here we will discuss our recent progress in the additive manufacturing of complex structures using hydrogels and various thermoset resins that are otherwise impossible to additively manufacture using alternative approaches. These structures are built by embedding the printed material within a temporary, thermoreversible, and biocompatible support fluid. This process, termed freeform reversible embedding of suspended hydrogels (FRESH), enables additive manufacturing of hydrogels with an elastic modulus less than 500 kPa. FRESH 3D printing also enables fabrication with thermoset and composite resins such as epoxies, acrylates, and siloxanes, and can host a range of polymerization mechanisms depending on the printed material, including ionic crosslinking, enzymes, pH change, heat/light exposure, and time-sensitive gelation approaches. We will demonstrate recent advances towards a range of new applications, including 3D printing of collagen for bioengineering functional tissue constructs and of silicone elastomers for patient-specific, wearable medical devices. Specific work is focused on cellularized collagen constructs to create functional cardiac tissues and extending these approaches to additional tissue and organ systems for in vitro disease modeling and in vivo regeneration.