We present a novel cellular metamaterial constructed from Origami building blocks based on Miura-ori fold. The proposed cellular metamaterial exhibits unusual properties some of which stemming from the inherent properties of its Origami building blocks, and others manifesting due to its unique geometrical construction and architecture. These properties include foldability with two fully-folded configurations, auxeticity (i.e., negative Poisson’s ratio), bistability, and self-locking of Origami building blocks to construct load-bearing cellular metamaterials. The kinematics and force response of the cellular metamaterial during folding were studied to investigate the underlying mechanisms resulting in its unique properties using analytical modeling and experiments.

Origami‐inspired mechanisms have demonstrated a variety of beneficial features including geometric complexity and structural resilience. However, a limited number of studies have focused on their programmability in kinetics and kinematics through rearranging the folding pattern. In this paper, an origami “string,” a slender structure with a programmable trajectory, is presented. The string is composed of a number of elements that can be individually programed to achieve a specific folding pattern and curvature. The mechanism has a single degree of freedom, allowing it to be actuated from one end while maintaining precise positioning along the entire string length. The relationship between the fold pattern and string path is simulated and experimentally validated, and its application as a robotic gripper and a biomimetic hand is demonstrated. These results demonstrate the capabilities of the proposed origami strings in accomplishing precise positioning and programed shape and function.

Origami designs offer extreme reconfigurability due to hinge rotation and facet deformation. This can be exploited to make lightweight metamaterials with controlled deployability and tunable properties. Here, we create a family of origami-inspired cellular metamaterials which can be programmed to have various stability characteristics and mechanical responses in three independent orthogonal directions. The cellular metamaterials were constructed from their origami unit cell that can have one or two admissible closed-loop configurations. The presence of the second closed-loop configuration leads to the emergence of bi-stability in the cellular metamaterial. We show that the stability and reconfigurability of the origami unit cell, and thus the constructed cellular metamaterials, can be programmed by manipulating the characteristic angles inherited from the origami pattern. Two examples of such programmable metamaterial with bi-stability in out-of-plane direction and anisotropic multi-stability in orthogonal directions are presented. Our study provides a platform to design programmable three-dimensional metamaterials significantly broadening the application envelope of origami. Introduction:Geometry induced instabilities are ubiquitous in nature due to their importance in influencing large changes in mechanical response and adding extra functionality to the structure. Examples include the closure of Venus flytrap plant [1], trapping mechanism of the bladderworts [2], buckling of drying colloidal droplets [3], and osmotically shrinking polymeric capsules [4]. Including instability in a materials design can similarly lead to added functionality and rapid shape change. In this context, using origami structures to harness instability is an exciting new area of research. Twisted origami square [5], cylindrical origami with Kresling and Miura-ori pattern [6,7], and rigid-foldable cellular structures with special hinge characteristics [8] are some examples of origami-inspired structures capable of exhibiting instability. More generally, over the past few decades, origami has truly evolved from an ancient Japanese art of paper folding into a rich scientific field bridging different disciplines [9]. However, in spite of the unlimited

Origami, widely known as the ancient Japanese art of paper folding, has recently inspired a new paradigm of design for mechanical metamaterials and deployable structural systems. However, lack of rationalized design guidelines and scalable manufacturing methods has hindered their applications. To address this limitation, we present analytical methods for designing origami-based closed-loop units with inherent foldability, and for predicting their folding response (e.g., folding force, bistability, and area and volume change by folding). These units can be employed as building blocks for application-driven design and modular construction of foldable structures with desired performance and manufacturing scalability.