Biodegradable, Sustainable Hydrogel Actuators with Shape and Stiffness Morphing Capabilities via Embedded 3D Printing

摘要

Despite the impressive performance of recent marine robots, many of theircomponents are non-biodegradable or even toxic and may negatively impactsensitive ecosystems. To overcome these limitations, biologically-sourcedhydrogels are a candidate material for marine robotics. Recent advances inembedded 3D printing have expanded the design freedom of hydrogeladditive manufacturing. However, 3D printing small-scale hydrogel-basedactuators remains challenging. In this study, Free form reversible embeddingof suspended hydrogels (FRESH) printing is applied to fabricate small-scalebiologically-derived, marine-sourced hydraulic actuators by printing thin-wallstructures that are water-tight and pressurizable. Calcium-alginate hydrogelsare used, a sustainable biomaterial sourced from brown seaweed. Thisprocess allows actuators to have complex shapes and internal cavities that aredifficult to achieve with traditional fabrication techniques. Furthermore, itdemonstrates that fabricated components are biodegradable, safely edible,and digestible by marine organisms. Finally, a reversible chelation-crosslinkingmechanism is implemented to dynamically modify alginate actuators’structural stiffness and morphology. This study expands the possible designspace for biodegradable marine robots by improving the manufacturability ofcomplex soft devices using biologically-sourced materials.