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The shape transformation of some biological systems inspires scientists to create sophisticated structures at the nano- and macro- scales. However, to be useful in engineering, the mechanics of governing such a spontaneous, parallel and large deformation must be well understood. In this study, a kirigami approach is used to fold a bilayer planar sheet featuring a specific pattern into a buckliball under a certain thermal stimulus. Importantly, this prescribed spherical object can retract into a much smaller sphere due to constructive buckling caused by radially inward displacement. By minimizing the potential strain energy, we obtain a critical temperature, below which the patterned sheet exhibits identical principal curvatures everywhere in the self-folding procedure and above which buckling occurs. The applicability of the theoretical analysis to the self-folding of sheets with a diversity of patterns is verified by the finite element method.
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... By using projection microstereo lithography, hollow particles with a similar mechanism could be fabricated and applied to drug delivery under various stimuli, such as pH, temperature and humid. Recently, we created a bilayer planar sheet in a specific pattern (figure 8(c)) and validate it can self-fold into a buckliball under thermal stimulus [109]. Noted that it is a kind of kirigami approach and the pattern can be well designed to allow the film folding into wanted structures. ...
... (a) The progressively deformed shapes of a buckliball[107]; (b) numerical simulation of an improved buckliball with large volume retraction ratio[108]; (c) the folding of a planar sheet to create a buckliball[101,109]. ...
Article
Being one of the commonest deformation modes for soft matters, shell buckling is the primary reason for the growth and nastic movement of many plants, as well as the formation of complex natural morphology. On-demand regulation of buckling-induced deformation associated with wrinkling, ruffling, folding, creasing and delaminating has profound implications for diverse scopes, which can be seen in its broad applications in microfabrication, 4D printing, actuator and drug delivery. This paper reviews the recent remarkable developments in the shell buckling of soft matters to explain the most representative natural morphogenesis from the perspectives of theoretical analysis in continuum mechanics, finite element analysis, and experimental validations. Imitation of buckling-induced shape transformation and its applications are also discussed for the innovations of sophisticated materials and devices in future.
... Similar to self-folding origami, kirigami can also self-deform under specific triggering methods. The basic means by which kirigami self-deforms is a nonuniform stress distribution that can be generated by different methods, such as bilayer materials with different properties, focused ion beams (FIBs), 10,161,172 temperature-responsive materials, 11,156,180,182 solvent-activated materials, 156 electroactive polymers, 179,188 magnetically activated materials, 178 shape-memory polymers, 177 photoactive materials, 163 and electrothermal materials. 173 The applications of self-deforming kirigami include shape morphing, 11,156,163,180,182 stents, 177 actuators for robotics, 161,163,178,179,188 MEMS, 173 tunable optical properties, 10,172 and tunable thermal expansion. ...
... The basic means by which kirigami self-deforms is a nonuniform stress distribution that can be generated by different methods, such as bilayer materials with different properties, focused ion beams (FIBs), 10,161,172 temperature-responsive materials, 11,156,180,182 solvent-activated materials, 156 electroactive polymers, 179,188 magnetically activated materials, 178 shape-memory polymers, 177 photoactive materials, 163 and electrothermal materials. 173 The applications of self-deforming kirigami include shape morphing, 11,156,163,180,182 stents, 177 actuators for robotics, 161,163,178,179,188 MEMS, 173 tunable optical properties, 10,172 and tunable thermal expansion. 11 Figure 6(g) shows propeller-shaped and pinwheel-shaped kirigamis made of gold film buckling under the triggering of an FIB. 10 Because of the tensile and compressive stresses introduced by the FIB, the kirigami pattern can be cut by a high-dose FIB and bent by a lowdose FIB. ...
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Once merely ancient arts, origami (i.e., paper folding) and kirigami (i.e., paper cutting) have in recent years also become popular for building mechanical metamaterials and now provide valuable design guidelines. By means of folding and cutting, two-dimensional thin-film materials are transformed into complex three-dimensional structures and shapes with unique and programmable mechanical properties. In this review, mechanical metamaterials based on origami and/or kirigami are categorized into three groups: (i) origami-based ones (with folding only), (ii) kirigami-based ones (with cutting only), and (iii) hybrid origami-kirigami-based ones (with both folding and cutting). For each category, the deformation mechanisms, design principles, functions, and applications are reviewed from a mechanical perspective.
... The beauty of nature is manifested through the fascinating structures of botanical/animal organs, such as furcate [1], lacunar [2] and reticular [3] structures, the formation of which has aroused considerable curiosity among scientists for decades [4]. Through the long-term process of evolution, the distributions of leaf veins have naturally developed into well-organized structures [5]. ...
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The stiffness and heat dissipation of thin planar structures in industrial engineering are taken as the background for this research. Plant leaves with various vein patterns, such as tobacco (Nicotiana tabacum L.) and chili (Capsicum annuum L.) leaves, are treated as the research objects. Through a combination of morphological and mechanical analysis, the distribution patterns and properties of leaf veins are mathematically characterized. A topological optimization algorithm is employed to simulate the vein growth process, thus revealing the effects of the mechanical and biological properties of different leaves on their vein morphologies. Additionally, the angles between the main and secondary veins are controlled to satisfy biological constraints. This comprehensive exploration of vein morphological formation can serve as a reference for the design of bionic thin planar structures in engineering.
... Fused deposition modeling (FDM), a fast and direct additive manufacturing technology, prints structures by accumulating ejected warmed thermoplastic fibers layerby-layer [1] and has been widely adopted in prototype fabrication [2], biomedical engineering [3,4], bionic structures [5], electronic devices [6], and drug delivery [7]. This rapid manufacturing technique is becoming a popular area of research that has been advanced by innovative technologies, methods, and materials. ...
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Additive manufacturing has the potential to provide novel solutions for fabricating complex structures. However, one of the main obstacles for such methods is the anisotropic mechanical properties of the manufactured product, which hinder the popularization of additive manufacturing in modern industries. Here, a simple yet versatile algorithm is introduced to produce isotropic products via optimizing the printing path. In this method, the workpiece is first separated into distinct areas in terms of the printing sequence, which increases the efficiency of the fabrication process. Subsequently, the printing path is schemed in each sub-region to allow a short extrusion length and low number of start-stop processes. Finally, this maze-like printing path is revised through a series of tensile tests and fracture surface analyses to validate the isotropy. Bending and indentation tests demonstrate that the samples present distinguished properties in terms of strength and isotropy in mechanical properties. Moreover, numerical and physical tests are implemented for validating the advantage of this maze-like pattern in preventing warping caused by residual stress. This work may play a significant role in printing molds that require isotropic properties.
... The fundamental principle of origami is to transform a flat sheet square (2-D) of paper into a finished sculpture (3-D) through folding and sculpting techniques along pre-defined creases. Because of its unique properties, origami has been imitated and developed to design foldable mechanisms (Hanna et al., 2014), self-deployable structures (Delimont et al., 2015), robots (Jayaram and Full, 2016), self-folding structures (Na et al., 2015), metamaterials (Overbelde et al., 2017), energy absorbing structures (Yang et al., 2016 and to solve plant structure folding (Couturier et al., 2013), soft matter folding (Lin et al., 2016) and even protein folding problems (Gethin and Sambrook, 1992). From an engineering viewpoint, mechanical properties of the crease for design-ing origami structures are of significant importance, which should be fully understood and characterised. ...
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Here we present the design of a 1.27g quadrupedal microrobot manufactured using “Pop-up book MEMS” the first such device capable of locomotion. Implementing popup assembly techniques enables manufacturing of the robot's exoskeleton and drivetrain transmissions from a single 23-layer laminate. Its demonstrated capabilities include payload capacity greater than 1.35g (106% of body mass), maneuverability on flat terrain, and high-speed locomotion up to 37cm/s. Additionally, locomotion performance is compared to a hand-assembled quadruped with similar design parameters. The results demonstrate that the pop-up manufacturing methodology enables more complex mechanisms while simultaneously increasing performance over hand-assembled alternatives.
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We report on a therapeutic approach using thermo-responsive multi-fingered drug eluting devices. These therapeutic grippers referred to as theragrippers are shaped using photolithographic patterning and are composed of rigid poly(propylene fumarate) segments and stimuli-responsive poly(N-isopropylacrylamide-co-acrylic acid) hinges. They close above 32 °C allowing them to spontaneously grip onto tissue when introduced from a cold state into the body. Due to porosity in the grippers, theragrippers could also be loaded with fluorescent dyes and commercial drugs such as mesalamine and doxorubicin, which eluted from the grippers for up to seven days with first order release kinetics. In an in vitro model, theragrippers enhanced delivery of doxorubicin as compared to a control patch. We also released theragrippers into a live pig and visualized release of dye in the stomach. The design of such tissue gripping drug delivery devices offers an effective strategy for sustained release of drugs with immediate applicability in the gastrointestinal tract.
Article
Fabrication of 3D objects using folding of thin films is a novel and very attractive research field. The manuscript overviews recent advances in development and application of polymer films, which are able to fold and form 3D structures.
Article
A previously developed geometrically nonlinear stress-curvature relation is expanded in this paper to allow for a less restrictive approximation of the midplane strains in a thin film/substrate system. The previous analysis is based on a minimization of the total strain energy and predicts a bifurcation in shape as the magnitude of intrinsic film stress increases. It is reviewed here and three new cases are presented. Expanding the approximating polynomials for the normal midplane strains and , has a small effect on the solution. However, allowing the midplane shear strain, , to be nonzero has a pronounced effect on the solution, particularly in the stress region near the bifurcation point.
Article
Thermally activated, untethered microgrippers can reach narrow conduits in the body and be used to excise tissue for diagnostic analyses. As depicted in the figure, the feasibility of an in vivo biopsy of the porcine bile duct using untethered microgrippers is demonstrated.
Article
Ion processing of the reactive surface of a free-standing polycrystalline metal film induces a flow of atoms into grain boundaries, resulting in plastic deformation. A thorough experimental and theoretical analysis of this process is presented, along with the demonstration of novel engineering concepts for precisely-controlled 3D-assembly at micro- and nanoscopic scales.
Article
Table of Contents Introduction Building Blocks Elephant Design Traditional Bases Folding Instructions Stealth Fighter. Snail. Valentine. Ruby-Throated Hummingbird. Baby. Splitting Points Folding Instructions Pteranodon. Goatfish. Grafting Folding Instructions Songbird 1. KNL Dragon. Lizard. Tree Frog. Dancing Crane. Pattern Grafting Folding Instructions Turtle. Western Pond Turtle. Koi. Tiling Folding Instructions Pegasus Circle Packing Folding Instructions Emu. Songbird 2. Molecules Folding Instructions Orchid Blossom. Silverfish. Tree Theory Folding Instructions Alamo Stallion. Roosevelt Elk. Box Pleating Folding Instructions Organist. Black Forest Cuckoo Clock. Uniaxial Box Pleating Folding Instructions Bull Moose Polygon Packing Crease Patterns Flying Walking Stick. Salt Creek Tiger Beetle. Longhorn Beetle. Camel Spider. Water Strider. Scarab Beetle. Cicada Nymph. Scarab HP. Cyclomatus metallifer. Scorpion HP. Euthysanius Beetle. Spur-Legged Dung Beetle. Hybrid Bases Folding Instructions African Elephant References Glossary of Terms Index
Article
Self-folding broadly refers to self-assembly processes wherein thin films or interconnected planar templates curve, roll-up or fold into three dimensional (3D) structures such as cylindrical tubes, spirals, corrugated sheets or polyhedra. The process has been demonstrated with metallic, semiconducting and polymeric films and has been used to curve tubes with diameters as small as 2nm and fold polyhedra as small as 100nm, with a surface patterning resolution of 15nm. Self-folding methods are important for drug delivery applications since they provide a means to realize 3D, biocompatible, all-polymeric containers with well-tailored composition, size, shape, wall thickness, porosity, surface patterns and chemistry. Self-folding is also a highly parallel process, and it is possible to encapsulate or self-load therapeutic cargo during assembly. A variety of therapeutic cargos such as small molecules, peptides, proteins, bacteria, fungi and mammalian cells have been encapsulated in self-folded polymeric containers. In this review, we focus on self-folding of all-polymeric containers. We discuss the mechanistic aspects of self-folding of polymeric containers driven by differential stresses or surface tension forces, the applications of self-folding polymers in drug delivery and we outline future challenges.
Article
Nanoscale self-folding of electron-beam lithography patterned templates is used to create 3D devices for optics and biosensing.
Article
Fabrication of 3D electronic structures in the micrometer-to-millimeter range is extremely challenging due to the inherently 2D nature of most conventional wafer-based fabrication methods. Self-assembly, and the related method of self-folding of planar patterned membranes, provide a promising means to solve this problem. Here, we investigate self-assembly processes driven by wetting interactions to shape the contour of a functional, nonplanar photovoltaic (PV) device. A mechanics model based on the theory of thin plates is developed to identify the critical conditions for self-folding of different 2D geometrical shapes. This strategy is demonstrated for specifically designed millimeter-scale silicon objects, which are self-assembled into spherical, and other 3D shapes and integrated into fully functional light-trapping PV devices. The resulting 3D devices offer a promising way to efficiently harvest solar energy in thin cells using concentrator microarrays that function without active light tracking systems.
Article
Smart materials: Preparation of PNIPAM core-shell microgels, with a single metal or silica nanoparticle in the core and low polydispersity, are achieved (see picture; cores are silica particles). A versatile method is used, which could be applied to other types of nanoparticles. (Figure Presented).
And The Modeling Of Leaves: An Interactive Computer Application PhD Degree Thesis thesis
  • S Jazebi
  • Kirigami Origami
Jazebi, S. Origami, Kirigami, And The Modeling Of Leaves: An Interactive Computer Application PhD Degree Thesis thesis. The University of Calgary (2012).
Self-assembly of carbon nanotubes into two-dimensional geometries using DNA origami templates
  • H T Maune
  • HT Maune