Water-Based Robotic Fabrication: Large-Scale Additive Manufacturing of Functionally Graded Hydrogel Composites via Multichamber Extrusion

Abstract Additive manufacturing (AM) of regenerated biomaterials is in its infancy despite the urgent need for alternatives to fuel-based products and in spite of the exceptional mechanical properties, availability, and biodegradability associated with water-based natural polymers. This study presents water-based robotic fabrication as a design approach and enabling technology for AM of biodegradable hydrogel composites. Our research focuses on the combination of expanding the dimensions of the fabrication envelope, developing structural materials for additive deposition, incorporating material-property gradients, and manufacturing architectural-scale biodegradable systems. This work presents a robotically controlled AM system to produce biodegradable-composite objects combining natural hydrogels, such as chitosan and sodium alginate, with other organic aggregates. It demonstrates the approach by designing, building, and evaluating the mechanics and controls of a multichamber extrusion system. Finally, it provides evidence of large-scale composite objects fabricated by our technology that display graded properties and feature sizes ranging from micro- to macroscale. Fabricated objects may be chemically stabilized or dissolved in water and recycled within minutes. Applications include the fabrication of fully recyclable products or temporary architectural components such as tent structures with graded mechanical and optical properties. Proposed applications demonstrate environmental capabilities such as water-storing structures, hydration-induced shape forming, and product disintegration over time.