Active origami by 4D printing

Abstract

Recent advances in three dimensional (3D) printing technology that allow multiple materials to be printed within each layer enable the creation of materials and components with precisely controlled heterogeneous microstructures. In addition, active materials, such as shape memory polymers, can be printed to create an active microstructure within a solid. These active materials can subsequently be activated in a controlled manner to change the shape or configuration of the solid in response to an environmental stimulus. This has been termed 4D printing, with the 4th dimension being the time-dependent shape change after the printing. In this paper, we advance the 4D printing concept to the design and fabrication of active origami, where a flat sheet automatically folds into a complicated 3D component. Here we print active composites with shape memory polymer fibers precisely printed in an elastomeric matrix and use them as intelligent active hinges to enable origami folding patterns. We develop a theoretical model to provide guidance in selecting design parameters such as fiber dimensions, hinge length, and programming strains and temperature. Using the model, we design and fabricate several active origami components that assemble from flat polymer sheets, including a box, a pyramid, and two origami airplanes. In addition, we directly print a 3D box with active composite hinges and program it to assume a temporary flat shape that subsequently recovers to the 3D box shape on demand.

HCI meets Material Science

“…In recent years, engineers have looked to the ancient Japanese tradition of origami to inspire the evolution of engineering structures that can be fabricated, assembled, stored and morphed in unique ways [72,177]. The applications of foldable structures are widespread and have been implemented in an array of practical scenarios including in the design and deployment of solar sails [211] and space telescopes [55,249], in sandwich panel cores [66,85], in the folding of sheet metal [53], in packaging and containers [52,251], in robotics [62,89,127,167], biomedical devices [65,122,190] and electronics [80,96,161,218,228,259].…”

Technological considerations for 4D printing: an overview

“…Chemical stimuli include chemicals, oxidant, and reductants and based on ionic strength and pH level, whereas biological stimuli include substances such as the presence of glucose and enzymes. Most experimental studies focused on the use of water [6][7][8][9], heat [10][11][12][13][14][15], a combination of heat and water [16,17] as well as a combination of heat and light [18]. The primary shape-shifting response or output are fold, curl, twist, expansion, and contraction [1,19,20].…”

Advanced Shape Memory Technology for Comfort Fitting

“…Although customized shoes might be fabricated via, for instance, 3D printing for better fitting [3,4], it mostly requires a tedious process of 3D foot scanning plus a still expensive fabrication process of printing. Such a type of one-to-one customized fabrication is actually a natural extension of tailored manufacturing in the past, which is opposite to mass fabrication for lowered cost but with minimum consideration for comfort fitting.…”