Crease Pattern Research Articles

The Role of Pretarsal Fascia in Upper Eyelid Crease Formation and its Implications in East Asians.

This study aims to investigate the role of pretarsal fascia in the formation of upper eyelid crease in East Asians. Through intraoperative fascia retraction observation, fascia-stretching test, histological examination, and anatomical analysis of pretarsal fascia and surrounding tissues, we explored the mechanical consequences and their impact on upper eyelid crease formation. The levator aponeurosis extension comprises three parts to impact sub-orbicularis fat pad mechanically. The pretarsal fascia is anatomically distinct from the aponeurosis extension but is influenced by its mechanic forces. Differential distribution of collagen fiber bundles within the pretarsal fascia can buffer and transmit the forces of aponeurosis extension, leading to diverse upper eyelid crease patterns. The factors determining upper eyelid crease are multifaceted, and the buffering-conduction theory of pretarsal fascia can explain both physiological and postoperative crease in East Asians. It determines the presence, depth, and stability of crease, laying the foundation for the formation of upper eyelid crease in East Asians. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Origami-Inspired Vacuum-Actuated Foldable Actuator Enabled Biomimetic Worm-like Soft Crawling Robot.

The development of a soft crawling robot (SCR) capable of quick folding and recovery has important application value in the field of biomimetic engineering. This article proposes an origami-inspired vacuum-actuated foldable soft crawling robot (OVFSCR), which is composed of entirely soft foldable mirrored origami actuators with a Kresling crease pattern, and possesses capabilities of realizing multimodal locomotion incorporating crawling, climbing, and turning movements. The OVFSCR is characterized by producing periodically foldable and restorable body deformation, and its asymmetric structural design of low front and high rear hexahedral feet creates a friction difference between the two feet and contact surface to enable unidirectional movement. Combining an actuation control sequence with an asymmetrical structural design, the body deformation and feet in contact with ground can be coordinated to realize quick continuous forward crawling locomotion. Furthermore, an efficient dynamic model is developed to characterize the OVFSCR's motion capability. The robot demonstrates multifunctional characteristics, including crawling on a flat surface at an average speed of 11.9 mm/s, climbing a slope of 3°, carrying a certain payload, navigating inside straight and curved round tubes, removing obstacles, and traversing different media. It is revealed that the OVFSCR can imitate contractile deformation and crawling mode exhibited by soft biological worms. Our study contributes to paving avenues for practical applications in adaptive navigation, exploration, and inspection of soft robots in some uncharted territory.

The rigid and flat-foldable kirigami cubes

Rigid and flat-foldable cubes generally exhibit excellent foldable properties and significant potential for designing three-dimensional (3D) deployable structures. However, a sealed cube cannot be folded rigidly, necessitating the introduction of slits, leading to kirigami cubes. This paper aims to explore a slit-arranging technique for cubes with straight-skeleton crease patterns to create rigid and flat-foldable kirigami cubes. Considering that slits are equivalent to movable prismatic joints, rules for transforming origami cubes into equivalent mechanisms are proposed. By formulating the relationships between the selection of movable prismatic joints and the degree of freedom (DOF) of the mechanism, we propose a non-enumerative prismatic-joint-based technique for arranging slits, which significantly establish the relationships between slit arrangements and DOF based on mechanism theory. Subsequently, various slit arrangements that align with the desired DOF are obtained. Furthermore, the characteristic that the slits are closed in both fully deployed and folded configurations facilitates the construction of a bistable cube with slits sealed by elastic membranes. Comprehensive parametric studies reveal that the peak energy between stable states can be custom-designed, demonstrating significant potential for deployable aerospace structures and mechanical metamaterials. This work would greatly advance the design of 3D deployable structures.

Simulation and design of isostatic thick origami structures

Thick origami structures are considered here as assemblies of polygonal panels hinged to each other along their edges according to a corresponding origami crease pattern. The determination of the internal actions in equilibrium with the external loads in such structures is not an easy task, owing to their high degree of static indeterminacy, and the likelihood of unwanted self-balanced internal actions induced by manufacturing imperfections. Here, we present a method for reducing the degree of static indeterminacy which can be applied to several thick origami structures to make them isostatic. The method utilizes sliding hinges, which allow relative translation along the hinge axis, to replace conventional hinges. After giving the analytical description of both types of hinges and describing a rigid folding simulation procedure based on the integration of the exponential map, we present the static analysis of a series of noteworthy examples based on the Miura-ori pattern, the Yoshimura pattern, and the Kresling pattern. Our method, based on kinematic-static duality, provides a novel design paradigm that can be applied for the design and realization of thick origami structures with adequate strength to resist external actions.

Reprogrammable, Recyclable Origami Robots Controlled by Magnetic Fields

Origami, the art of paper folding, has emerged as a versatile technique for crafting intricate 3D structures from 2D sheets. Combined with the magnetic actuation, origami paper becomes the building blocks for cost‐effective, wirelessly controllable magnetic robots. Herein, a biodegradable magnetic paper with excellent formability and recyclability is developed, facilitating its convenient utilization and disposal. The programable magnetic paper, fabricated with specific magnetization and crease patterns, enables the transformation of 2D sheets into predetermined 3D structures. Leveraging the lightweight and pliable nature of paper‐based materials, exceptional control of origami robots with fast response is demonstrated, enabling a wide range of locomotion. Furthermore, the paper‐based approach enables the incorporation of electronic functionality into magnetic actuators. By introducing conductive nanoparticles into magnetic paper, an electrically conductive substance is created. Constructing electronic circuits and integrating electronic components onto the paper‐based printed circuit board platform enables the repairing of broken circuits inside complicated equipment and optical sensing of surrounding environments in conjunction with locomotive robots. The origami robots have a huge potential to be facilitated in diverse fields with various functions, demonstrating complex locomotion, and integrating chemical, optical, thermal, and mechanical sensors for monitoring environmental conditions in hard‐to‐reach locations. The array of possibilities holds significant promise for the widespread application of these origami magnetic robots across a diverse spectrum of research fields in soft robotics.

Region crossing change on origami and link

Region Select is a game originally defined on a knot projection. In this paper, Region Select on an origami crease pattern is introduced and investigated. As an application, a new unlinking number associated with region crossing change is defined and discussed.

Linear and nonlinear topology optimization of origami structures based on crease pattern and axial rigidity

Linear and nonlinear topology optimization of origami structures based on crease pattern and axial rigidity

Reconfigurable Thick-Panel Structures Based on a Stacked Origami Tube

Abstract Variable crease origami that exhibits crease topological morphing allows a given crease pattern to be folded into multiple shapes, greatly extending the reconfigurability of origami structures. However, it is a challenge to enable the thick-panel forms of such crease patterns to bifurcate uniquely and reliably into desired modes. Here, thick-panel theory combined with cuts is applied to a stacked origami tube with multiple bifurcation paths. The thick-panel form corresponding to the stacked origami tube is constructed, which can bifurcate exactly between two desired modes without falling into other bifurcation paths. Then, kinematic analysis is carried out, and the results reveal that the thick-panel origami tube is kinematically equivalent to its zero-thickness form with one degree-of-freedom (DOF). In addition, a reconfigurable physical prototype of the thick-panel origami tube is produced, which achieves reliable bifurcation control through a single actuator. Such thick-panel origami tubes with controllable reconfigurability have great potential engineering applications in the fields of morphing systems such as mechanical metamaterials, morphing wings, and deployable structures.

Identification of Dermal Crease Patterns as a Link between Genetics and Periodontitis: Reliability and Credibility

Identification of Dermal Crease Patterns as a Link between Genetics and Periodontitis: Reliability and Credibility

Dermatoglyphic palmar pattern variations in congenitally deaf and mute subjects

Background: Dermatoglyphics have the unique merit of retaining all their peculiarities unchanged throughout life, and afford in consequence an incomparably surer criterion of identity than any other bodily feature. The rationale for studying dermatoglyphic features is derived from the fact that development of dermal ridges and congenital deafness seems to develop at around the same time. Methods: The material for the study consisted of palm prints of congenitally deaf and mute children of 100 subjects with congenital deafness and muteness between 5-21 years of age and 50 control of similar age group with normal hearing and speech were chosen. The principal patterns of thenar/ I interdigital, interdigital II, interdigital III, interdigital IV and hypothenar area were noted. Position of axial triradius, ‘atd’ angle, pattern of palmar Flexion Creases, presence as well as pattern of the Simian Line and the Sydney Line were recorded. Results: The percentage of open field was maximum in subjects in thenar / interdigital area I. and in interdigital area IV. The mean a-b, c-d and atd angle ridge palmar ridge count was less in subjects in comparison to controls. Highly statistically significant results were obtained between subjects and control for the simian crease pattern when both hands were considered together in which the percentage of transitional type was more than the typical simian crease in subjects. Conclusion: When combined with other clinical and investigative features, dermatoglyphic study can serve as a diagnostic impression and can be advocated as a useful screening device.

Shear and shear-induced normal responses of origami cylinders relate to their structural asymmetries

Origami cylinders have been studied extensively under compression, however, their normal force response under shear deformation is still ill-understood. We experimentally studied the shear-induced normal force of these systems and provided a simple model to predict this response in Yoshimura and Kresling origami cylinders in the range of small deformations. Besides that, the effect of disorder is little understood in those origami patterns. Therefore, we investigate the disorder effect and show it can lead to diverse normal responses perpendicular to shear deformation in crumpled Yoshimura, with slopes of the force perpendicular to torsion that can be positive, zero, or negative depending on the disordered pattern of folds. The disorder leads to an asymmetry concerning the shearing direction, which we quantified via an asymmetry index from the 2D Fast Fourier transform spectrum of the crease pattern images. This asymmetry index is found to be linearly related to the slope of the normal force-torsion relationship.

Creasing the British Museum: Topology Finding of Crease Patterns for Shell Structures

Creasing the British Museum: Topology Finding of Crease Patterns for Shell Structures

Graded in-plane Miura origami as crawling robots and grippers

In this work, we propose a variation of Miura origami which, different from the existing out-of-plane bending Miura origami, has an in-plane bent configuration due to its graded crease pattern. By combining with the one-way shape memory alloy spring, we show that the proposed graded Miura origami can serve as a smart actuator and can be applied to drive crawling robots or grippers. First, we constructed a physical model of the graded Miura origami, from which a curvature-programmable geometric equation is proposed. Then, in addition to providing a mechanical model that can capture the mechanical behavior of the initial force–displacement relationship of the curved beam, we show that the proposed curved origami has a different mechanical behavior compared to the corresponding simple flexible arch, specifically if realized by silicon rubbers. By arranging anisotropic friction to the feet, the origami robot can crawl with an omega-elongation/compression motion like an inchworm. With a closed-loop current source control system using a high-frequency pulse width modulation-based topology, where the strain state of the arched origami is detected by a demodulator-free fiber Bragg grating sensor, the average speed of the origami crawling robot can reach 2.72 mm/s. In addition, by arranging three graded Miura origami, a gripper capable of lifting a weight of 518.5 g can be formed, where the carried load is over 4.5 times its own weight.

Rigid-flexible coupled origami robots via multimaterial 3D printing

Soft robots have significant advantages in flexibility and adaptability and have potential applications in the field of engineering. Unlike traditional manufacturing methods, three-dimensional (3D) printing provides a fast way to fabricate customized and multi-functional robots. However, the fabrication of soft robots requires multimaterial printers and the high-accuracy multi-step assembly process. Among them, fused deposition modeling (FDM) technology has taken the lead compared to other 3D printing methods due to its ease of use, accuracy, and repeatability. However, the FDM multimaterial printing has not been thoroughly explored. Here, we proposed a rigid and flexible material integrated printing approach based on FDM 3D printing technology and reported a cable-driven flexible pipe robot based on Yoshimura origami crease patterns. The implementations show that the robot can realize four-direction bending effectively by the corresponding drive control, which indicates the feasibility of our design and manufacturing method. The proposed approach paves an effective way to design and fabricate the rigid-flexible robot and other devices in the future.

Tunable stiffness design of curved-crease origami and extended quasi-zero stiffness vibration isolator

A kind of origami tube based on the curved crease, which has a tunable stiffness, was designed, fabricated, tested, and extended to the concept of a quasi-zero stiffness (QZS) vibration isolator. The regulating function of crease stiffness on the overall origami stiffness without changes in the crease pattern was verified by single-crease models. With various opening ratios along the creases, three tubes composed of mirrored single-crease origami were designed, fabricated by 3D printing, and compressively tested. The test results present the potential of the approach of QZS. Further, the elastic-frictionless origami tubes were redesigned and simulated to obtain the target stiffness. The cubic term fitting of the load curve was adopted by the harmonic balance method to solve the steady-state vibration response, and then the simulation results obtained by the finite element method (FEM) were compared. The study shows that the designed elastic-frictionless isolator has a good low-frequency vibration isolation performance. The concept of the simple stiffness control method of curved-crease origami provides more practice options for high static and low dynamic stiffness systems.

Analytical and numerical investigation of second-order infinitesimal mechanism in rigid origami

This study investigates second-order infinitesimal mechanisms and bifurcation paths of rigid origamis with multiple-degree-of-freedom mechanisms. A truss model, consisting of pin-connected rigid bars, is employed for the infinitesimal mechanism analysis. The conditions for the existence of a second-order infinitesimal mechanism are analytically solved to investigate the combinations of the infinitesimal mechanism modes that are the potential finite mechanisms. Analytical solutions for simple crease patterns show the bifurcation of the deformation paths at the flat state, some disappeared combinations of the mechanism modes in a single path, and the relationship between the nodal displacement and axial force distribution. This comprehensive analysis, using analytical solutions, lays the foundation for understanding bifurcation and finite mechanism of rigid origami, which have not yet been fully explored. These properties are also verified in the finite deformation paths generated by large deformation analysis of a frame model consisting of frame members and hinges, which is suitable for the analysis using general-purpose finite element analysis software. The second-order infinitesimal mechanisms found in this study are confirmed to be able to be extended to the finite mechanisms.

Variable Stiffness Fibers Enabled Universal and Programmable Re-Foldability Strategy for Modular Soft Robotics.

Origami is a rich source of inspiration for creating soft actuators with complex deformations. However, implementing the re-foldability of origami on soft actuators remains a significant challenge. Herein, a universal and programmable re-foldability strategy is reported to integrate multiple origami patterns into a single soft origami actuator, thereby enabling multimode morphing capability. This strategy can selectively activate and deactivate origami creases through variable stiffness fibers. The utilization of these fibers enables the programmability of crease pattern quantity and types within a single actuator, which expands the morphing modes and deformation ranges without increasing their physical size and chamber number. The universality of this approach is demonstrated by developing a series of re-foldable soft origami actuators. Moreover, these soft origami actuators are utilized to construct a bidirectional crawling robot and a multimode soft gripper capable of adapting to object size, grasping orientation, and placing orientation. This work represents a significant step forward in the design of multifunctional soft actuators and holds great potential for the advancement of agile and versatile soft robots.

Bistable morphology analysis of the flexible single-vertex origami unit cell

In origami structures, it is necessary to study the novel properties of the single-vertex origami unit cell first, which is the basic unit that could be assembled into a large-scale origami tessellation with complex patterns. When the elasticity of the sheet and the kinematics of the crease are combined, nearly all single-vertex origami unit cells with an arbitrary crease pattern are foldable and bistable. In this case, the stable morphology of the unit cell is dominated by both the crease rotation and the shell deformation. In this work, two models are proposed for the solution of the bistability of the flexible origami unit cell. First, a flexible boundary conical shell model is proposed, by introducing crease mechanics based on the previous work. This linear model can be easily solved for flexible f-cones with arbitrary crease patterns by a certain assembly scheme. Moreover, to consider the nonlinearity, the discrete creased model (DCM) is further developed for the stable state solution of the arbitrary origami unit cell. Thereafter, the results obtained by the two models are verified with the corresponding FE simulations. Based on the normalized crease stiffness, the coupling effect between the crease and the shell is analyzed. The core deformation mechanism of flexible origami unit cells is classified into three cases: the crease-dominated case, the crease-shell coupled case, and the shell-dominated case. Additionally, the energy ratio of crease rotation to shell bending at the snapping state is found to be approximately proportional to the normalized crease stiffness.

A flat-foldable equiangular spiral folding pattern inspired by sunflowers for deployable structures

Flasher origami pattern has been widely utilized to improve the stowage efficiency of deployable structures. Nevertheless, flasher origami cannot be folded fully flat, and they still have great potential for optimization in terms of storage volume and folding creases. In this paper, a flat foldable equiangular spiral folding pattern inspired by the sunflower disk is introduced. Then, a parametric design method for this equiangular spiral crease diagram is introduced in detail. Subsequently, a kinematic model of the equiangular spiral folding pattern is established based on the kinematic equivalence between rigid origami and spherical linkages. A simulation of the developed model demonstrates that the equiangular spiral folding pattern can be folded flat. Using the folded ratio as an evaluation index, the calculated results and experiments show that the equiangular spiral crease pattern can yield fewer creases and improve stowage efficiency in comparison to flasher origami pattern. Equiangular spiral folding pattern can save a considerable amount of space and provide a new approach to spatially deployable structures.

An origami like 3D patterned cellulose-based scaffold for bioengineering cardiovascular applications

In this work we describe the manufacturing of cellulosic, cell compatible scaffolds with an inherent 3D origami crease pattern for applications in cardiac tissue engineering. Different cellulosic materials were studied, among them cotton linters, fibers obtained from eucalyptus, pine, spruce and lyocell. Formed sheets made of cotton linters were chosen for further study due to the highest biocompatibility and mechanical properties best suited for cardiomyocytes in wet and dry conditions: E - modulus of 0.8 GPa, tensile strength of 4.7 MPa and tensile strength in wet environment of 2.28 MPa. Cell alignment is desired to achieve directional contraction of the cardiac tissue, and several options were investigated to achieve fiber alignment, e.g. a dynamic sheet former and Rapid Köthen sheet former. Although the orientation was minimal, cells cultured on the cellulose fibers grew and aligned along the fibers. Origami inspired crease patterns were applied to the cellulose scaffolds in order to introduce directional flexibility beneficial for cardiac contraction. The transfer of a Miura-ori crease pattern was successfully applied in two ways: folding of the dried sheet between PET foils pre-formed in a 3D printed mold, and in situ wet fiber molding on a 3D-patterned mesh mounted in the sheet former’s sieve section. The latter approach enables upscaling for potential mass production.