Origami-inspired active structures: a synthesis and review

Abstract

Origami, the ancient art of paper folding, has inspired the design of engineering devices and structures for decades. The underlying principles of origami are very general, which has led to applications ranging from cardboard containers to deployable space structures. More recently, researchers have become interested in the use of active materials (i.e., those that convert various forms of energy into mechanical work) to effect the desired folding behavior. When used in a suitable geometry, active materials allow engineers to create self-folding structures. Such structures are capable of performing folding and/or unfolding operations without being kinematically manipulated by external forces or moments. This is advantageous for many applications including space systems, underwater robotics, small scale devices, and self-assembling systems. This article is a survey and analysis of prior work on active self-folding structures as well as methods and tools available for the design of folding structures in general and self-folding structures in particular. The goal is to provide researchers and practitioners with a systematic view of the state-of-the-art in this important and evolving area. Unifying structural principles for active self-folding structures are identified and used as a basis for a quantitative and qualitative comparison of numerous classes of active materials. Design considerations specific to folded structures are examined, including the issues of crease pattern identification and fold kinematics. Although few tools have been created with active materials in mind, many of them are useful in the overall design process for active self-folding structures. Finally, the article concludes with a discussion of open questions for the field of origami-inspired engineering.

Origami tubes assembled into stiff, yet reconfigurable structures and metamaterials

“…The materials and methods used for fabricating, actuating, and assembling these systems can vary greatly with length scale. On the microscale, metallic and polymer films or, more often, layered composites consisting of stiff and flexible materials can be folded by inducing current, heat, or a chemical reaction (16,17). Largescale origami structures can be constructed from thickened panels connected by hinges and can be actuated with mechanical forces (11,18,19).…”

An origami-inspired cargo drone

“…We resort to an origami design to make the drone foldable with a simple arm movement. Origami structures have been shown to achieve high strength-to-weight ratios [10][11] and a significant size reduction by folding [12][13]. Among the possible origami designs [14][15] (Fig.…”

“…Traditional origami structures [12] are composed of tiles joined by folds. In the cage, tiles are replaced by struts connected by flexible joints in order to obtain a spatial structure that does not obstruct the airflow generated by the enclosed propellers.…”

Smart Delivery Systems with Shape Memory and Self-Folding Polymers

“…Also without any external interference, such as human control, self-folding can be attributed to the self-assembly mechanism. These mechanisms can be patterned templates or thin films which can be folded, curved, or rolled-up to become spirals, tubes, and cylindrical tubes [73,74]. Selffolding can occur spontaneously or in response to stimuli such as light, pH [75], temperature, magnetic field, or solvent [76,77].…”