ABSTRACT
We propose an algorithmic framework of a pluripotent structure evolving from a simple compact structure into diverse complex 3D structures for designing the shape-transformable, reconfigurable, and deployable structures and robots. Our algorithmic approach suggests a way of transforming a compact structure consisting of uniform building blocks into a large, desired 3D shape. Analogous to a fertilized egg cell that can grow into a preprogrammed shape according to coded information, compactly stacked panels named the zygote structure can evolve into arbitrary 3D structures by programming their connection path. Our stacking algorithm obtains this coded sequence by inversely stacking the voxelized surface of the desired structure into a tree. Applying the connection path obtained by the stacking algorithm, the compactly stacked panels named the zygote structure can be deployed into diverse large 3D structures. We conceptually demonstrated our pluripotent evolving structure by energy-releasing commercial spring hinges and thermally actuated shape memory alloy hinges, respectively. We also show that the proposed concept enables the fabrication of large structures in a significantly smaller workspace.
ABSTRACT
Falling leaves flutter from side to side due to passive and intrinsic fluid-body coupling. Exploiting the dynamics of passive fluttering could lead to fresh perspectives for the locomotion and manipulation of thin, planar objects in fluid environments. Here, we show that the time-varying density distribution within a thin, planar body effectively elicits minimal momentum control to reorient the principal flutter axis and propel itself via directional fluttery motions. We validated the principle by developing a swimming leaf with a soft skin that can modulate local buoyancy distributions for active flutter dynamics. To show generality and field applicability, we demonstrated underwater maneuvering and manipulation of adhesive and oil-skimming sheets for environmental remediation. These findings could inspire future intelligent underwater robots and manipulation schemes.
ABSTRACT
Lymphedema is a non-curative chronic swelling caused by impairment of the lymphatic system, affecting up to 250 million patients worldwide. The patients suffer from low quality of life because of discomfort and reduced range of motion due to the swelling. Severe swellings can be immediately mediated with special massaging technique known as the Manual Lymphatic Drainage (MLD). Limitations of MLD involves long travel distances, the cost of regular treatment sessions, and the lack of lymphedema specialists. Since MLD is performed very gently, described as caressing a baby's head, soft wearable robotics with its inherent compliance and safety is the perfect solution to creating a light and safe wearable lymphedema massaging device. In this paper, origami-inspired soft fabric pneumatic actuator is developed that creates not only normal force, but also shear force which is essential in the performance of MLD. The shear is created by the unfolding of the Z-shaped fold-lines as the actuator is inflated. One Z-folded actuator module of 30 x 60 mm dimension with a single fold of 15 mm fold height creates maximum shear force of about 1.5 N and stroke displacement of about 30 mm when subjected to compression loading of 5 N. The range of forces exerted can be tuned by varying the tension of the compressive clothing covering the actuators, and the stroke displacement can be varied by changing the parameter of the actuator module itself, such as the fold height and the number of the folds. The modules can also be repeatedly actuated under compressive clothing, and therefore, the developed actuator modules have high potential as a wearable massaging device.
Subject(s)
Lymphedema/therapy , Massage , Textiles , Wearable Electronic Devices , Humans , Manual Lymphatic Drainage , PressureABSTRACT
Nature demonstrates adaptive and extreme shape morphing via unique patterns of movement. Many of them have been explained by monolithic shape-changing mechanisms, such as chemical swelling, skin stretching, origami/kirigami morphing, or geometric eversion, that were successfully mimicked in artificial analogs. However, there still remains an unexplored regime of natural morphing that cannot be reproduced in artificial systems by a "single-mode" morphing mechanism. One example is the "dual-mode" morphing of Eurypharynx pelecanoides (commonly known as the pelican eel), which first unfolds and then inflates its mouth to maximize the probability of engulfing the prey. Here, we introduce pelican eel-inspired dual-morphing architectures that embody quasi-sequential behaviors of origami unfolding and skin stretching in response to fluid pressure. In the proposed system, fluid paths were enclosed and guided by a set of entirely stretchable origami units that imitate the morphing principle of the pelican eel's stretchable and foldable frames. This geometric and elastomeric design of fluid networks, in which fluid pressure acts in the direction that the whole body deploys first, resulted in a quasi-sequential dual-morphing response. To verify the effectiveness of our design rule, we built an artificial creature mimicking a pelican eel and reproduced biomimetic dual-morphing behavior. By compositing the basic dual-morphing unit cells into conventional origami frames, we demonstrated architectures of soft machines that exhibit deployment-combined adaptive gripping, crawling, and large range of underwater motion. This design principle may provide guidance for designing bioinspired, adaptive, and extreme shape-morphing systems.
