Architected Vacuum Driven Origami Structures via Direct Ink Writing of RTV Silicone

Abstract

Recent advances in soft robotics, wearable devices, and deployable systems have sparked tremendous interest in origami structures due to their controllable volume changes and shape-morphing capabilities. Despite significant progress in the design and fabrication of origami using traditional materials such as paper, textiles, thermoplastics, and thick panels, challenges persist in creating soft elastomeric origami designs that allow for precise, programmable deformations. This work proposes an architected approach for designing and 3D printing Room Temperature Vulcanization (RTV) silicone-based origami structures actuated by negative pressure. Central to this approach is a flexible hinge design, which enables controlled bending angles ranging from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$45^{\circ }$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$90^{\circ }$</tex-math></inline-formula> upon the application of vacuum actuation. This architected method simplifies the complex folding of origami structures by strategically arranging the flexible hinges. A Python-based software tool was developed to generate custom G-code directly from user-defined design parameters, streamlining the design-to-fabrication pipeline for Direct Ink Writing (DIW) RTV silicone-based origami parts. Initial fabrication experiments were conducted using a three-step print-assemble-bond approach. As an alternative to eliminating manual processing steps, a monolithic flexible hinge with a cavity was printed within a gel support. This paper introduces a hinge design library and discusses the design-to-fabrication workflow for origami-inspired active structures.