Programmable Origami Tubes with Temperature Actuation Using Liquid Crystal Elastomers

Abstract

Origami is a field of promise in engineering as it provides the ability to create elements with tunable properties by changing the fold angles of the structure. Origami tubes can have their stiffness, height and energy absorption characteristics programmed by reconfiguring their cross-section. These tubes can be used as elements of a metamaterial with variable global properties, or as structural elements with tunable properties. Actuation of origami is often done in a tethered manner; however, this approach can be bulky and restricts the range of applications of the structures. Namely, a metamaterial would be limited if each element required a tethered actuation mechanism. We develop a tube with untethered actuation using liquid crystal elastomer (LCE) hinges at each fold that can be programmed at sub-100 ºC temperatures. We define a Miura-Ori tube and outline the equations governing its internal geometrical relationships before simulating the cross-sectional change of the tube to visualize its kinematics and assess the likelihood of ideal folding. We synthesize and characterize the printing of a linear main-chain liquid crystalline polymer and the properties of the resulting programmed LCE. We develop a novel tube fabrication method aiming to minimize the steps requiring human input. Finally, we demonstrate and characterize the actuation of an example Miura-Ori tube composed of four unit cells.