Engineering › Mechanical Engineering

Advanced Materials and Mechanics

Works Count: 30791

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Description

This cluster of papers explores the advancements in 4D printing technologies, focusing on biomimetic materials, polymer films, liquid crystal elastomers, shape memory polymers, actuators, wrinkling patterns, bioinspired materials, soft robotics, hydrogels, and mechanical metamaterials. The research covers a wide range of applications and functionalities enabled by the development of these innovative materials and printing techniques.

Keywords

Biomimetic; Polymer Films; Liquid Crystal Elastomers; Shape Memory Polymers; Actuators; Wrinkling Patterns; Bioinspired Materials; Soft Robotics; Hydrogels; Mechanical Metamaterials

Nematic liquid single crystal elastomers

1991-12-01

Jürgen Küpfer , Heino Finkelmann

Using origami design principles to fold reprogrammable mechanical metamaterials

2014-08-07

Jesse L. Silverberg , Arthur A. Evans , Robert R. McLeod +4 more

Folding robots and metamaterials The same principles used to make origami art can make self-assembling robots and tunable metamaterials—artificial materials engineered to have properties that may not be found in … Folding robots and metamaterials The same principles used to make origami art can make self-assembling robots and tunable metamaterials—artificial materials engineered to have properties that may not be found in nature (see the Perspective by You). Felton et al. made complex self-folding robots from flat templates. Such robots could potentially be sent through a collapsed building or tunnels and then assemble themselves autonomously into their final functional form. Silverberg et al. created a mechanical metamaterial that was folded into a tessellated pattern of unit cells. These cells reversibly switched between soft and stiff states, causing large, controllable changes to the way the material responded to being squashed. Science , this issue p. 644 , p. 647 ; see also p. 623

Silicone Rubber Substrata: A New Wrinkle in the Study of Cell Locomotion

1980-04-11

Albert K. Harris , Patricia Wild , David Stopak

When tissue cells are cultured on very thin sheets of cross-linked silicone fluid, the traction forces the cells exert are made visible as elastic distortion and wrinkling of this substratum. … When tissue cells are cultured on very thin sheets of cross-linked silicone fluid, the traction forces the cells exert are made visible as elastic distortion and wrinkling of this substratum. Around explants this pattern of wrinkling closely resembles the "center effects" long observed in plasma clots and traditionally attributed to dehydration shrinkage.

Some constitutive equations for liquid crystals

1968-01-01

F. M. Leslie

Sphere Packings, Lattices and Groups.

1989-06-01

H. S. M. Coxeter , J. H. Conway , N. J. A. Sloane

The second edition of this book continues to pursue the question: what is the most efficient way to pack a large number of equal spheres in n-dimensional Euclidean space? The … The second edition of this book continues to pursue the question: what is the most efficient way to pack a large number of equal spheres in n-dimensional Euclidean space? The authors also continue to examine related problems such as the kissing number problem, the covering problem, the quantizing problem, and the classification of lattices and quadratic forms. Like the first edition, the second edition describes the applications of these questions to other areas of mathematics and science such as number theory, coding theory, group theory, analog-to-digital conversion and data compression, n-dimensional crystallography, and dual theory and superstring theory in physics.

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On the Crushing Mechanics of Thin-Walled Structures

1983-12-01

Tomasz Wierzbicki , W. Abramowicz

A self-consistent theory is presented which describes the crushing behavior of a class of thin-walled structures. Assuming a rigid-plastic material and using the condition of kinematic continuity on the boundaries … A self-consistent theory is presented which describes the crushing behavior of a class of thin-walled structures. Assuming a rigid-plastic material and using the condition of kinematic continuity on the boundaries between rigid and deformable zones, a basic folding mechanism is constructed. This mechanism closely reproduces all the main features of folds and wrinkles actually observed on typical crumpled sheet metal structures. Calculations based on the energy balance postulate show that two-thirds of the plastic energy is always dissipated through inextensional deformations at stationary and moving plastic hinge lines. The extensional deformations are confined to relatively small sections of the shell surface but they account for the remaining one-third of the dissipated energy. The theory is illustrated by application to the problem of progressive folding of thin-walled rectangular columns. A good correlation is obtained with existing experimental data as far as the mean crushing force and the geometry of the local collapse mode is concerned.

Preparation of Mesoscale Hollow Spheres of TiO2 and SnO2 by Templating Against Crystalline Arrays of Polystyrene Beads

2000-02-01

Z. Zhong , Yadong Yin , Byron D. Gates +1 more

Mesoscale hollow spheres of ceramic materials can be prepared by templating an appropriate sol–gel precursor against a crystalline array of monodisperse polystyrene beads, as demonstrated here. Spheres of well-controlled, uniform … Mesoscale hollow spheres of ceramic materials can be prepared by templating an appropriate sol–gel precursor against a crystalline array of monodisperse polystyrene beads, as demonstrated here. Spheres of well-controlled, uniform size and homogeneous wall thickness result, as can be seen from the Figure, which shows the TEM cross-sectional view of an array of TiO2 hollow spheres.

RIBBONS 2.0

1991-10-01

Mike Carson

The program RIBBONS 2.0 allows real-time viewing of solid shaded ribbon models of macromolecules. The primary features of the software are the ability to create a wide variety of styles … The program RIBBONS 2.0 allows real-time viewing of solid shaded ribbon models of macromolecules. The primary features of the software are the ability to create a wide variety of styles of ribbon drawings interactively and to toggle between various coloring schemes chosen to reflect assorted geometrical and biochemical properties. Spheres, cylinders, dots, polygons and text are also supported. The auxiliary programs included make RIBBONS 2.0 a powerful tool for visual structural analysis as well as for presentation graphics. The program is currently available only for the Silicon Graphics 4D series of workstations. A port to the Evans & Sutherland ESV workstation employing PEX is under development.

Geometry of Miura-folded metamaterials

2013-02-11

Mark Schenk , Simon D. Guest

This paper describes two folded metamaterials based on the Miura-ori fold pattern. The structural mechanics of these metamaterials are dominated by the kinematics of the folding, which only depends on … This paper describes two folded metamaterials based on the Miura-ori fold pattern. The structural mechanics of these metamaterials are dominated by the kinematics of the folding, which only depends on the geometry and therefore is scale-independent. First, a folded shell structure is introduced, where the fold pattern provides a negative Poisson's ratio for in-plane deformations and a positive Poisson's ratio for out-of-plane bending. Second, a cellular metamaterial is described based on a stacking of individual folded layers, where the folding kinematics are compatible between layers. Additional freedom in the design of the metamaterial can be achieved by varying the fold pattern within each layer.

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Bio-Inspired Polymer Composite Actuator and Generator Driven by Water Gradients

2013-01-10

Mingming Ma , Liang Guo , Daniel G. Anderson +1 more

Mini Mighty Muscle Actuators—or artificial muscles—take electrical or chemical energy and convert it into mechanical force. Typically, actuators made from polymers can show large deformations, but cannot generate a lot … Mini Mighty Muscle Actuators—or artificial muscles—take electrical or chemical energy and convert it into mechanical force. Typically, actuators made from polymers can show large deformations, but cannot generate a lot of force. Ma et al. (p. 186 ; see the Perspective by Kim and Kwon ) describe a polymer composite based on a modified polypyrrole that expands in response to water absorption. The composite was able to generate large stresses and forces, and offered a high work density approaching those of the best conducting polymer electrochemical actuators. Magnetic nanoparticles incorporated into polymer films were used to control the locomotion of the actuator.

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Directed bending of a polymer film by light

2003-09-01

Yanlei Yu , Makoto Nakano , Tomiki Ikeda

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Printed artificial cilia from liquid-crystal network actuators modularly driven by light

2009-06-28

Casper L. van Oosten , Cees W. M. Bastiaansen , Dirk J. Broer

Extreme selectivity in the lift-off of epitaxial GaAs films

1987-12-28

Eli Yablonovitch , T.J. Gmitter , J. P. Harbison +1 more

We have discovered conditions for the selective lift-off of large area epitaxial AlxGa1−xAs films from the substrate wafers on which they were grown. A 500-Å-thick AlAs release layer is selectivity … We have discovered conditions for the selective lift-off of large area epitaxial AlxGa1−xAs films from the substrate wafers on which they were grown. A 500-Å-thick AlAs release layer is selectivity etched away, leaving behind a high-quality epilayer and a reusable GaAs substrate. We have measured a selectivity of ≳107 between the release layer and Al0.4Ga0.6As. This process relies upon the creation of a favorable geometry for the outdiffusion of dissolved H2 gas from the etching zone.

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Liquid Crystalline Elastomers as Actuators and Sensors

2010-05-28

C. C. Ohm , Martin Brehmer , Rudolf Zentel

This review collects recent developments in the field of liquid crystalline elastomers (LCEs) with an emphasis on their use for actuator and sensor applications. Several synthetic pathways leading to crosslinked … This review collects recent developments in the field of liquid crystalline elastomers (LCEs) with an emphasis on their use for actuator and sensor applications. Several synthetic pathways leading to crosslinked liquid crystalline polymers are discussed and how these materials can be oriented into liquid crystalline monodomains are described. By comparing the actuating properties of different systems, general structure-property relationships for LCEs are obtained. In the final section, how these materials can be turned into usable devices using different interdisciplinary techniques are described.

A New Opto-Mechanical Effect in Solids

2001-06-15

Heino Finkelmann , Etsushi Nishikawa , Gerald G. Pereira +1 more

We propose that large, reversible shape changes in solids, of between $10%--400%$, can be induced optically by photoisomerizing monodomain nematic elastomers. Empirical and molecular analysis of shape change and its … We propose that large, reversible shape changes in solids, of between $10%--400%$, can be induced optically by photoisomerizing monodomain nematic elastomers. Empirical and molecular analysis of shape change and its relation to thermal effects is given along with a simple model of the dynamics of response. Our experiments demonstrate these effects for the first time and theory is compared qualitatively with our results.

Artificial Muscles from Fishing Line and Sewing Thread

2014-02-20

Carter S. Haines , Márcio D. Lima , Na Li +7 more

The high cost of powerful, large-stroke, high-stress artificial muscles has combined with performance limitations such as low cycle life, hysteresis, and low efficiency to restrict applications. We demonstrated that inexpensive … The high cost of powerful, large-stroke, high-stress artificial muscles has combined with performance limitations such as low cycle life, hysteresis, and low efficiency to restrict applications. We demonstrated that inexpensive high-strength polymer fibers used for fishing line and sewing thread can be easily transformed by twist insertion to provide fast, scalable, nonhysteretic, long-life tensile and torsional muscles. Extreme twisting produces coiled muscles that can contract by 49%, lift loads over 100 times heavier than can human muscle of the same length and weight, and generate 5.3 kilowatts of mechanical work per kilogram of muscle weight, similar to that produced by a jet engine. Woven textiles that change porosity in response to temperature and actuating window shutters that could help conserve energy were also demonstrated. Large-stroke tensile actuation was theoretically and experimentally shown to result from torsional actuation.

Designing Responsive Buckled Surfaces by Halftone Gel Lithography

2012-03-08

Jungwook Kim , James Hanna , Myunghwan Byun +2 more

Self-actuating materials capable of transforming between three-dimensional shapes have applications in areas as diverse as biomedicine, robotics, and tunable micro-optics. We introduce a method of photopatterning polymer films that yields … Self-actuating materials capable of transforming between three-dimensional shapes have applications in areas as diverse as biomedicine, robotics, and tunable micro-optics. We introduce a method of photopatterning polymer films that yields temperature-responsive gel sheets that can transform between a flat state and a prescribed three-dimensional shape. Our approach is based on poly(N-isopropylacrylamide) copolymers containing pendent benzophenone units that allow cross-linking to be tuned by irradiation dose. We describe a simple method of halftone gel lithography using only two photomasks, wherein highly cross-linked dots embedded in a lightly cross-linked matrix provide access to nearly continuous, and fully two-dimensional, patterns of swelling. This method is used to fabricate surfaces with constant Gaussian curvature (spherical caps, saddles, and cones) or zero mean curvature (Enneper's surfaces), as well as more complex and nearly closed shapes.

Equation of State for Nonattracting Rigid Spheres

1969-07-15

Norman F. Carnahan , K.E. Starling

A new equation of state for rigid spheres has been developed from an analysis of the reduced virial series. Comparisons with existing equations show that the new formula possesses superior … A new equation of state for rigid spheres has been developed from an analysis of the reduced virial series. Comparisons with existing equations show that the new formula possesses superior ability to describe rigid-sphere behavior.

A buckling-based metrology for measuring the elastic moduli of polymeric thin films

2004-07-11

Christopher M. Stafford , Christopher Harrison , Kathryn L. Beers +7 more

Calculated elastic constants for stress problems associated with semiconductor devices

1973-01-01

William A. Brantley

Theoretical estimates or experimental determinations of stress fields associated with semiconductor devices are generally simplified with the aid of two elastic constants, Young's modulus E and Poisson's ratio ν. In … Theoretical estimates or experimental determinations of stress fields associated with semiconductor devices are generally simplified with the aid of two elastic constants, Young's modulus E and Poisson's ratio ν. In this paper, a generalized expression for ν has been derived for arbitrary orientations of cubic semiconductor crystals, and the variation of E, ν, and E/(1-ν) for directions within the important {111}, {100}, and {110} planes is examined. The results show that isotropic elasticity theory is exact for all directions within {111} planes and that the composite elastic constant E/(1-ν) which frequently occurs in problems of practical interest is also invariant for all directions within {100} planes. Numerical values for the various elastic constants are tabulated for GaAs, GaP, Si, and Ge.

Assembly of micro/nanomaterials into complex, three-dimensional architectures by compressive buckling

2015-01-09

Sheng Xu , Zheng Yan , Kyung‐In Jang +7 more

Popping materials and devices from 2D into 3D Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu et al. develop an … Popping materials and devices from 2D into 3D Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu et al. develop an ingenious design strategy for the microfabrication of complex geometric 3D mesostructures that derive from the out-of-plane buckling of an originally planar structural layout (see the Perspective by Ye and Tsukruk). Finite element analysis of the mechanics makes it possible to design the two 2D patterns, which is then attached to a previously strained substrate at a number of points. Relaxing of the substrate causes the patterned material to bend and buckle, leading to its 3D shape. Science , this issue p. 154 ; see also p. 130

Poly(N-isopropylacrylamide): experiment, theory and application

1992-01-01

Howard G. Schild

Multistable Architected Materials for Trapping Elastic Strain Energy

2015-06-18

Sicong Shan , Sung Hoon Kang , Jordan R. Raney +5 more

3D printing and numerical analysis are combined to design a new class of architected materials that contain bistable beam elements and exhibit controlled trapping of elastic energy. The proposed energy-absorbing … 3D printing and numerical analysis are combined to design a new class of architected materials that contain bistable beam elements and exhibit controlled trapping of elastic energy. The proposed energy-absorbing structures are reusable. Moreover, the mechanism of energy absorption stems solely from the structural geometry of the printed beam elements, and is therefore both material- and loading-rate independent.

Photomobile Polymer Materials: Towards Light‐Driven Plastic Motors

2008-06-03

Munenori Yamada , Mizuho Kondo , Jun‐ichi Mamiya +4 more

Can light drive a motor? Azobenzene-containing liquid-crystalline elastomers (LCEs) and their composite materials have the potential to show three-dimensional movement by light irradiation. With the LCE laminated films, a first … Can light drive a motor? Azobenzene-containing liquid-crystalline elastomers (LCEs) and their composite materials have the potential to show three-dimensional movement by light irradiation. With the LCE laminated films, a first light-driven plastic motor has been developed, which can convert light energy directly into a continuous rotation without the aid of batteries, electric wires, or gears. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The packing of α-helices: simple coiled-coils

1953-09-10

Francis Crick

It is shown that when a-helices of the Same sense pack together they will probably do so about 20 ° away from parallel.For very long chains this may lead to … It is shown that when a-helices of the Same sense pack together they will probably do so about 20 ° away from parallel.For very long chains this may lead to a coiled-coil.The two simplest models --the two-strand rope and the three-strand rope--are described, and used to illustrate the ,diffraction theory already developed.It is shown that they would give a diffuse a-pattern.Possible examples of these models are briefly discussed.

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3D Printing of Free Standing Liquid Metal Microstructures

2013-07-04

Collin Ladd , Ju‐Hee So , John F. Muth +1 more

This paper describes a method to direct-write 3D liquid metal microcomponents at room temperature. The thin oxide layer on the surface of the metal allows the formation of mechanically stable … This paper describes a method to direct-write 3D liquid metal microcomponents at room temperature. The thin oxide layer on the surface of the metal allows the formation of mechanically stable structures strong enough to stand against gravity and the large surface tension of the liquid. The method is capable of printing wires, arrays of spheres, arches, and interconnects. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Nested self-similar wrinkling patterns in skins

2005-03-06

Kirill Efimenko , Mindaugas Rackaitis , Evangelos Manias +3 more

Soft matter with hard skin: From skin wrinkles to templating and material characterization

2006-01-01

Jan Genzer , Jan Groenewold

The English-language dictionary defines wrinkles as “small furrows, ridges, or creases on a normally smooth surface, caused by crumpling, folding, or shrinking”. In this paper we review the scientific aspects … The English-language dictionary defines wrinkles as “small furrows, ridges, or creases on a normally smooth surface, caused by crumpling, folding, or shrinking”. In this paper we review the scientific aspects of wrinkling and the related phenomenon of buckling. Specifically, we discuss how and why wrinkles/buckles form in various materials. We also describe several examples from everyday life, which demonstrate that wrinkling or buckling is indeed a commonplace phenomenon that spans a multitude of length scales. We will emphasize that wrinkling is not always a frustrating feature (e.g., wrinkles in human skin), as it can help to assemble new structures, understand important physical phenomena, and even assist in characterizing chief material properties.

Geometry and Physics of Wrinkling

2003-02-19

Enrique Cerda , L. Mahadevan

The wrinkling of thin elastic sheets occurs over a range of length scales, from the fine scale patterns in substrates on which cells crawl to the coarse wrinkles seen in … The wrinkling of thin elastic sheets occurs over a range of length scales, from the fine scale patterns in substrates on which cells crawl to the coarse wrinkles seen in clothes. Motivated by the wrinkling of a stretched elastic sheet, we deduce a general theory of wrinkling, valid far from the onset of the instability, using elementary geometry and the physics of bending and stretching. Our main result is a set of simple scaling laws; the wavelength of the wrinkles lambda approximately K(-1/4), where K is the stiffness due to an "elastic substrate" effect with a multitude of origins, and the amplitude of the wrinkle A approximately lambda. These could form the basis of a highly sensitive quantitative wrinkling assay for the mechanical characterization of thin solid membranes.

Mechanics of Motor Proteins and the Cytoskeleton

2002-03-01

Jonathon Howard , RL Clark

Preface - Introduction - PART I: PHYSICAL PRINCIPLES - Mechanical Forces - Mass, Stiffness, and Damping of Proteins - Thermal Forces and Diffusion - Chemical Forces - Polymer Mechanics - … Preface - Introduction - PART I: PHYSICAL PRINCIPLES - Mechanical Forces - Mass, Stiffness, and Damping of Proteins - Thermal Forces and Diffusion - Chemical Forces - Polymer Mechanics - PART II: CYTOSKELETON - Structures of Cytoskeletal Filaments - Mechanics of the Cytoskeleton - Polymerization of Cytoskeletal Filaments - Force Generation by Cytoskeletal Filaments - Active Polymerization - PART III: MOTOR PROTEINS - Structures of Motor Proteins - Speeds of Motors - ATP Hydrolysis - Steps and Forces - Motility Models: From Crossbridges to Motion - Afterword - Appendix - Bibliography - Index

Mouldable liquid-crystalline elastomer actuators with exchangeable covalent bonds

2013-11-29

Zhiqiang Pei , Yang Yang , Qiaomei Chen +3 more

Nonlinear analyses of wrinkles in a film bonded to a compliant substrate

2005-06-24

Zhenyu Huang , Wei Hong , Zhigang Suo

Fast liquid-crystal elastomer swims into the dark

2004-04-21

Miguel A. Camacho‐López , Heino Finkelmann , Peter Palffy‐Muhoray +1 more

Photomechanics of Liquid‐Crystalline Elastomers and Other Polymers

2007-01-10

Tomiki Ikeda , Jun‐ichi Mamiya , Yanlei Yu

Abstract Muscle is a transducer that can convert chemical energy into mechanical motion. To construct artificial muscles, it is desirable to use soft materials with high mechanical flexibility and durability … Abstract Muscle is a transducer that can convert chemical energy into mechanical motion. To construct artificial muscles, it is desirable to use soft materials with high mechanical flexibility and durability rather than hard materials such as metals. For effective muscle‐like actuation, materials with stratified structures and high molecular orders are necessary. Liquid‐crystalline elastomers (LCEs) are superior soft materials that possess both the order of liquid crystals and the elasticity of elastomers (as they contain polymer networks). With the aid of LCEs, it is possible to convert small amounts of external energy into macroscopic amounts of mechanical energy. In this Review, we focus on light as an energy source and describe the recent progress in the area of soft materials that can convert light energy into mechanical energy directly (photomechanical effect), especially the photomechanical effects of LCEs with a view to applications for light‐driven LCE actuators.

Multifunctionality and control of the crumpling and unfolding of large-area graphene

2013-01-18

Jianfeng Zang , Seunghwa Ryu , Nicola M. Pugno +4 more

A method for building self-folding machines

2014-08-07

Samuel M. Felton , Michael T. Tolley , Erik D. Demaine +2 more

Origami can turn a sheet of paper into complex three-dimensional shapes, and similar folding techniques can produce structures and mechanisms. To demonstrate the application of these techniques to the fabrication … Origami can turn a sheet of paper into complex three-dimensional shapes, and similar folding techniques can produce structures and mechanisms. To demonstrate the application of these techniques to the fabrication of machines, we developed a crawling robot that folds itself. The robot starts as a flat sheet with embedded electronics, and transforms autonomously into a functional machine. To accomplish this, we developed shape-memory composites that fold themselves along embedded hinges. We used these composites to recreate fundamental folded patterns, derived from computational origami, that can be extrapolated to a wide range of geometries and mechanisms. This origami-inspired robot can fold itself in 4 minutes and walk away without human intervention, demonstrating the potential both for complex self-folding machines and autonomous, self-controlled assembly.

Programmable and adaptive mechanics with liquid crystal polymer networks and elastomers

2015-10-22

Timothy J. White , Dirk J. Broer

Biomimetic 4D printing

2016-01-25

A. Sydney Gladman , Elisabetta A. Matsumoto , Ralph G. Nuzzo +2 more

Photocontrol of fluid slugs in liquid crystal polymer microactuators

2016-09-01

Jiu‐an Lv , Yuyun Liu , Jia Wei +3 more

A review of 4D printing

2017-03-01

Farhang Momeni , Seyed M.Mehdi Hassani.N , Xun Liu +1 more

Making waves in a photoactive polymer film

2017-06-01

Anne Hélène Gelebart , Dirk J. Mulder , Michael Varga +5 more

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Flexible mechanical metamaterials

2017-10-17

Katia Bertoldi , Vincenzo Vitelli , Johan Christensen +1 more

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Three-dimensional mechanical metamaterials with a twist

2017-11-23

Tobias Frenzel , Muamer Kadic , Martin Wegener

Getting twisted with metamaterials In the classical picture of solid mechanics, deformation in response to stress is constrained owing to limitations on the degrees of freedom. For instance, when you … Getting twisted with metamaterials In the classical picture of solid mechanics, deformation in response to stress is constrained owing to limitations on the degrees of freedom. For instance, when you push on a material, you do not expect it to twist in response. Frenzel et al. designed a mechanical metamaterial with a pronounced twist to the left or right when pushed (see the Perspective by Coulais). Designing this type of chirality for a macroscopic material is unexpected, but it points to a more general strategy for developing materials with unusual deformation behavior. Science , this issue p. 1072 ; see also p. 994

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Printing ferromagnetic domains for untethered fast-transforming soft materials

2018-06-01

Yoonho Kim , Hyunwoo Yuk , Ruike Renee Zhao +2 more

Advances in 4D Printing: Materials and Applications

2018-11-26

Xiao Kuang , Devin J. Roach , Jiangtao Wu +5 more

Abstract 4D printing has attracted tremendous interest since its first conceptualization in 2013. 4D printing derived from the fast growth and interdisciplinary research of smart materials, 3D printer, and design. … Abstract 4D printing has attracted tremendous interest since its first conceptualization in 2013. 4D printing derived from the fast growth and interdisciplinary research of smart materials, 3D printer, and design. Compared with the static objects created by 3D printing, 4D printing allows a 3D printed structure to change its configuration or function with time in response to external stimuli such as temperature, light, water, etc., which makes 3D printing alive. Herein, the material systems used in 4D printing are reviewed, with emphasis on mechanisms and potential applications. After a brief overview of the definition, history, and basic elements of 4D printing, the state‐of‐the‐art advances in 4D printing for shape‐shifting materials are reviewed in detail. Both single material and multiple materials using different mechanisms for shape changing are summarized. In addition, 4D printing of multifunctional materials, such as 4D bioprinting, is briefly introduced. Finally, the trend of 4D printing and the perspectives for this exciting new field are highlighted.

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A review of recent research on bio-inspired structures and materials for energy absorption applications

2019-10-01

Ngoc San Ha , Guoxing Lu

Voxelated soft matter via multimaterial multinozzle 3D printing

2019-11-13

Mark A. Skylar‐Scott , J. Howard Mueller , Claas Willem Visser +1 more

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Voxelated liquid crystal elastomers

2015-02-27

Taylor H. Ware , Michael E. McConney , Jeong Jae Wie +2 more

Dynamic control of shape can bring multifunctionality to devices. Soft materials capable of programmable shape change require localized control of the magnitude and directionality of a mechanical response. We report … Dynamic control of shape can bring multifunctionality to devices. Soft materials capable of programmable shape change require localized control of the magnitude and directionality of a mechanical response. We report the preparation of soft, ordered materials referred to as liquid crystal elastomers. The direction of molecular order, known as the director, is written within local volume elements (voxels) as small as 0.0005 cubic millimeters. Locally, the director controls the inherent mechanical response (55% strain) within the material. In monoliths with spatially patterned director, thermal or chemical stimuli transform flat sheets into three-dimensional objects through controlled bending and stretching. The programmable mechanical response of these materials could yield monolithic multifunctional devices or serve as reconfigurable substrates for flexible devices in aerospace, medicine, or consumer goods.

Graphene kirigami

2015-07-28

Melina Blees , Arthur Barnard , Peter A. Rose +7 more

Sphere Packings, Lattices and Groups

1993-01-01

John H. Conway , N. J. A. Sloane

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Studying gastrulation by invagination: The bending of a cell sheet by mechanical cell properties using 3D deformable cell based simulations

2025-06-25

Roland Dries , Kim Y Renders , Jaap A. Kaandorp | PLoS Computational Biology

Studying the bending of a cell sheet in vivo, like invagination in embryos, can be complex due to a multitude of cellular processes and properties that interact with each other. … Studying the bending of a cell sheet in vivo, like invagination in embryos, can be complex due to a multitude of cellular processes and properties that interact with each other. Computer simulations can help to unravel this process. 2D computer simulations, however, lack the ability to take into account the effect three-dimensional properties, like endodermal plate shape and cell number, have on the shape of an embryo. Therefore, we developed a 3D cell-based model, that is able to simulate cells as separate deformable entities with a conserved cell volume. A blastula is formed by adhering the cells together as a sphere. The simulation results showed that changing individual mechanical properties, like cell stiffness, cell-cell adhesion, and the apical constriction factor, had a direct effect on the cell’s behavior and future shape. These properties influenced the ability of a cell sheet to bend and eventually change the global shape of the embryo. The observed shape transitions the endodermal region goes through during the inward bending of the cell sheet in the simulation, can give an insight into the mechanisms involved, and timing of events in biological model organisms. Changing geometrical properties (endodermal plate shape, endodermal cell number and the start position of constriction), which is not possible in 2D models, showed that the inwards bending is more dependent on the number of cells involved than on the shape of the endodermal region, and thus that the invagination process is very robust to irregularities. When qualitatively comparing our simulation results to biological data from literature, we saw that our simulations did not exactly reproduce the shapes observed in nature. This might indicate that additional mechanisms are playing a role during invagination.

Nonlinear postbuckling analysis of functionally graded graphene origami-enabled auxetic metamaterial plates with bi-directionally stepped thickness

2025-06-24

Peng Shi , Nguyễn Văn Hoàng , Pham Trung Thanh | Mechanics Based Design of Structures and Machines

Supramolecular Liquid Crystal Elastomer Adhesives: Role of Internal Damping and Hydrogen Bonding

2025-06-24

Subi Choi , Suk‐kyun Ahn | Advanced Functional Materials

Abstract Liquid crystal elastomers (LCEs) have attracted attention as materials for pressure‐sensitive adhesives (PSAs) owing to their high internal damping resulting from mesogen reorientation. However, the roles that mesogen reorientation … Abstract Liquid crystal elastomers (LCEs) have attracted attention as materials for pressure‐sensitive adhesives (PSAs) owing to their high internal damping resulting from mesogen reorientation. However, the roles that mesogen reorientation and interfacial interactions play in overall adhesion remain unclear. In this study, a series of supramolecular LCE‐based PSAs are prepared by systematically varying the liquid crystal (LC) content and hydrogen bond (H‐bond) density to investigate their effects on internal damping, soft elasticity, and adhesion strength. A decreased LC content of the PSAs reduces both internal damping and soft elasticity, resulting in weaker adhesion. When H‐bonds are introduced using non‐mesogenic monomers in the rigid segment, the mesogen reorientation is restricted, thereby decreasing adhesion. In contrast, incorporating H‐bonds into the chain extender (or soft segment) of the supramolecular LCEs improves the adhesion strength with increasing H‐bond density, provided the LC content is high. Therefore, the adhesion of supramolecular LCEs is primarily governed by internal damping rather than by H‐bond interactions. Moreover, solvent vapor annealing enables reversible adhesion in the supramolecular LCEs by transiently weakening H‐bonds and improving surface contact. The non‐thermal approach demonstrated in this study yields LCE‐based PSAs for heat‐sensitive applications such as medical adhesives, skin patches, and semiconductor processing.

Research on dynamics of synchronous deployment of supporting mechanism and cylindrical envelope used for individual escape capsule

2025-06-24

Boyan Chang , Haiyang Zhu , Shuai Mo +1 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

The emergency escape equipments are indispensable for submarine design. Due to the constraint of the narrow space, it is currently a matter of focus to design an individual-escape-capsule which can … The emergency escape equipments are indispensable for submarine design. Due to the constraint of the narrow space, it is currently a matter of focus to design an individual-escape-capsule which can be folded and deployed quickly and be launched from torpedo tubes. In this paper, a foldable cylindrical individual-escape-capsule including rigid deployable supporting mechanism and elastic envelope is proposed inspired by Kresling origami. The mobility of deployable supporting mechanism is analyzed based on screw theory. Its constraint screw system and reciprocal screw system are obtained and corresponding helical motion with variable pitch is obtained to establish the solution models of kinetic energy and gravitational potential energy. An approach used to describe the featured deformation characteristic of cylindrical envelope is proposed by combining shear Hooke’s law with strain energy density. The analysis of total potential energy, including potential energy of supporting mechanism and strain energy in envelope, reveals a clear bistable state where both the fully collapsed and fully deployed states exhibit lower energy. An energy barrier existed between these two equilibrium states indicates that the capsule is “easy deploy and hard collapse.” Finally, the dynamics model is built by Lagrange equation and the bistable characteristic is verified by numerical simulation. General theory and method can be summarized as important theoretical foundation for design and implementation of the IEC.

New Semiconductor Substrate Materials

2025-06-24

Dorin O. Neacșu | CRC Press eBooks

Architected Liquid Crystal Elastomer Lattices with Programmable Energy Absorption

2025-06-23

Rodrigo Telles , Julie A. Jackson , Jorge Barrera +7 more | Advanced Materials

Abstract Architected LCE lattices are fabricated with flow‐induced alignment via direct ink writing and systematically characterized their shape morphing, stiffness, and energy absorption behavior across strain rates spanning six orders … Abstract Architected LCE lattices are fabricated with flow‐induced alignment via direct ink writing and systematically characterized their shape morphing, stiffness, and energy absorption behavior across strain rates spanning six orders of magnitude from 10 −3 to 10 3 s −1 . It is shown that architected liquid crystal elastomer (LCE) lattices exhibit superior energy absorption compared to their non‐mesogenic (silicone) counterparts. Importantly, the LCE‐to‐silicone energy absorption ratios are up to 18‐fold higher at the highest strain rate tested. A finite element model that captures their shape‐morphing response is developed, which exhibits excellent agreement with the experimental observations. The work opens new avenues for designing and fabricating LCE lattices with programmable alignment, shape morphing, and mechanics.

Body Temperature Actuated Liquid Crystal Elastomers from Hyper Tensile Preprogramming

2025-06-23

Lin Xu , Chen Zhu , Samuel C. Lamont +6 more | Advanced Functional Materials

Abstract Creating thermally actuated liquid crystal elastomers (LCE) traditionally requires mechanical pre‐straining to cure in an aligned state, with higher pre‐strains generally improving alignment and actuation. However, excessive pre‐strains risk … Abstract Creating thermally actuated liquid crystal elastomers (LCE) traditionally requires mechanical pre‐straining to cure in an aligned state, with higher pre‐strains generally improving alignment and actuation. However, excessive pre‐strains risk damaging the material, making it difficult to quantitatively relate synthesis strategies with mechanical behavior. Here, a method allowing pre‐strains up to 2500% while preserving sample integrity is introduced. Using this method, scaling laws are established that relate actuator thickness and pre‐strain to performance, showing that actuation speed scales with a power‐law factor of 0.7. The actuators presented here exhibit an superior energy density of 1.5 MJ m⁻³ and demonstrate a highly sensitive bending actuation mode in ultrathin (20 µm) samples, responsive to human body temperature. A comprehensive thermomechanical analysis of these materials based on modern theories in nematic elastomers and structure–property relationships is provided. Finally, two soft robotic designs utilizing the material's rapid recovery are demonstrated, achieving cyclic behaviors unattainable in traditionally pre‐strained liquid crystal elastomers.

The Influence of Concentration and Type of Salts on the Behaviour of Linear Actuators Based on PVA Hydrogel Activated by AC Power

2025-06-23

Aleksey V. Maksimkin , M.Yu. Zadorozhnyy , Kseniia V. Filippova +3 more | Gels

The creation of quick-reacting electrically conductive polymers for use as actuators driven by low electrical currents is now seen as an important issue. Enhancing the electrical conductivity of hydrogels through … The creation of quick-reacting electrically conductive polymers for use as actuators driven by low electrical currents is now seen as an important issue. Enhancing the electrical conductivity of hydrogels through the incorporation of conductive fillers, like salts, can reduce the necessary actuating voltage. However, several important questions arise about how the type of salt chosen and its concentration will affect not only the activation efficiency of the actuators but also the structure of the hydrogels utilized. In this study, to enhance the electrical conductivity of the hydrogel and lower the necessary activation voltage of the hydrogel actuators, lithium chloride (LiCl) and sodium chloride (NaCl) were incorporated as conductive fillers into the polyvinyl alcohol (PVA) polymer matrix. To determine the deformation of actuators, as well as the activation and relaxation times and efficiencies during activation, linear actuators capable of being activated through extension/contraction (swelling/shrinking) cycles were developed and examined based on the LiCl/NaCl content, applied voltage, and frequency. The main finding is that the required actuating voltage was lowered by up to 20 V by adding an equal mass of salt in relation to the PVA mass content. With a load of around 20 kPa, it was observed that the extension deformation for PVA/NaCl-based actuators can achieve 75%, while in contraction deformation, can reach 17%. Additionally, for the PVA/LiCl-based actuators, the extension deformation can reach 87%, while during contraction deformation, it can reach 22%. The degree of swelling in the PVA/NaCl hydrogels was generally less than that in the PVA/LiCl hydrogels, which was associated with the finding that the actuators prepared from PVA/NaCl hydrogels delivered an output that was 10–15% lower than those made from PVA/LiCl hydrogels across different testing cycles. Furthermore, adding salt increases the degree of crosslinking, which can explain why increased crosslinking leads to reduced deformation when exposed to AC voltage. These actuators can find extensive use in soft robotics, artificial muscles, medical applications, and aerospace industries.

3D Hyperbolic Kirigami Metamaterials With Tunable Auxeticity and Multistability

2025-06-23

Yu Lei , Yan Wang , Rong Cui +5 more | Advanced Science

Kirigami mechanical metamaterials provide exceptional tunability in mechanical properties and morphing capabilities, exhibiting great potential for deployable and actuatable devices. However, most kirigami structures can only deform freely within a … Kirigami mechanical metamaterials provide exceptional tunability in mechanical properties and morphing capabilities, exhibiting great potential for deployable and actuatable devices. However, most kirigami structures can only deform freely within a 2D plane, with limited out-of-plane deformability, making them inadequate for constructing periodic objects with arbitrary 3D shapes. Here, a novel class of 3D mechanical metamaterials with hyperbolic kirigami tessellations has been developed. By projecting hyperbolic kirigami templates onto three types of triply periodic minimal surfaces, candidate structures are developed with remarkable properties. An extreme negative Poisson's ratio of -1 and tunable mechanical multistability are uncovered through theoretical analysis, numerical simulations, and experiments thanks to the flexible kirigami geometry. Notably, the structure achieves a maximum volume expansion of up to 488% during auxetic morphing. Furthermore, programmable morphing behaviors are demonstrated through voxelated assemblies of kirigami unit cells with varying geometrical parameters. The novel design strategy presented in this work based on hyperbolic kirigami tessellations opens up new avenues toward auxetic and multistable mechanical metamaterials with broad applications spanning shape-morphing architectures, deployable space structures, and soft machines.

Flexure-based guiding structure with enhanced additively manufactured particle damper

2025-06-23

Zhong Chen , Wenxin Zhang , Siyue Li +1 more | Smart Materials and Structures

Abstract Enhancing passive damping in the flexure-based guiding structures of nanopositioning stages can boost motion control bandwidth. This paper introduces a new flexure-based guiding structure incorporating additively-manufactured particle dampers, which … Abstract Enhancing passive damping in the flexure-based guiding structures of nanopositioning stages can boost motion control bandwidth. This paper introduces a new flexure-based guiding structure incorporating additively-manufactured particle dampers, which are expected to deliver superior damping performance. In the laser powder bed fusion (LPBF) process, particle dampers are created by deliberately leaving unfused powder. Meanwhile, resonant stepped cantilever beams are innovatively integrated along the neutral axis of the powder cavity. These beams, through their deflection, amplify impacts and friction among surrounding particles, thereby particularly enhancing damping near the resonant frequency. A comprehensive design framework for resonant beams in embedded LPBF-enhanced dampers is developed, based on a detailed damping enhancement mechanism and a particle-compression equivalent model. Experimental results confirm that the enhanced damper demonstrates excellent damping adaptability and a significant damping enhancement effect, especially at the structure's resonant frequency. This study emphasizes the potential of LPBF technology in creating advanced damping solutions for flexure-based mechanisms.

A Rigid Origami Elliptic-Hyperbolic Vertex Duality

2025-06-21

Thomas C. Hull | Results in Mathematics

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Concentric ice-templating of ultracompressible tough hydrogels with bioinspired circumferentially aligned architecture

2025-06-20

Wenxi Gu , Shuqi Yang , Dazhe Zhao +7 more | Science Advances

Materials with circumferentially aligned fibers, such as intervertebral discs and arteries, are abundant in nature but challenging to replicate artificially, despite their mechanical advantages. Although ice-templating can create bioinspired materials, … Materials with circumferentially aligned fibers, such as intervertebral discs and arteries, are abundant in nature but challenging to replicate artificially, despite their mechanical advantages. Although ice-templating can create bioinspired materials, the achievable structures remain limited to simple forms, such as honeycomb, lamellar, and radial structures. Here, we developed a unique ice-templating technique that constructs circumferential fibrous structures in hydrogels through slow freezing. Enhanced with rotary compression annealing, these hydrogels exhibit record-breaking features that cannot concurrently be achieved in conventional ice-templated and top-performing tough hydrogels, including high tensile properties, isotropic fatigue threshold of 2320 joules per square meter, ultracompressibility (8% strain after 500 cycles), and extraordinary burst pressure of 1.6 bar while maintaining 85 weight % water content. These properties enable opportunities in robotics, including hydrogel pneumatic grippers and an untethered bioinspired robotic fish that exhibits high-force actuation and long-term robustness. Our approach enriches the diversity of bioinspired structures in artificial materials, establishing exceptional mechanical properties through cross-length scale structural design.

VACM: a 3D-printed High Performance Vacuum-actuated Origami Soft Actuator

2025-06-20

Shashwat Sharma , W. Hua , Maadaa Bayarsaikhan +3 more | Journal of Medical Robotics Research

Overview of plant-derived biomaterials

2025-06-20

Ahmet Yılmaz , İlker Büyük | Communications Faculty of Science University of Ankara Series C Biology Geological Engineering and Geophysical Engineering

Humans have been using plant-derived biomaterials throughout the history and they have an important place in today’s daily life. They have a wide range of uses, from biotechnological to medical … Humans have been using plant-derived biomaterials throughout the history and they have an important place in today’s daily life. They have a wide range of uses, from biotechnological to medical purposes. Plant-derived biomaterials possess various implementation in many fields including food industry, health care, biomedical science, cosmetics, energy science, environmental health and drug-gene delivery. Biomaterials have evolved to tissue-specific smart polymers since their discovery. Many biotechnological applications have allowed the production of biomaterials with different structures and shapes. Furthermore, latest studies demonstrated that constitutive organization and surface topographies of plants might also be beneficial for many biomaterial production processes. In this article, the history, classification, properties and application areas of biomaterials are explained by supporting studies. As a conclusion, it is inescapable for scientists to realise that plants are affordable, maintainable and regenerative platforms, and thus, they are optimal resources for generation of organic biomaterials. In this review, important current developments in the field of plant-derived biomaterials are also discussed.

SoAR (Soft Aerial Robot) – Origami-Inspired Morphing Fuselage Extends Fixed-Wing Flight Capabilities

2025-06-19

Çağdaş D. Önal , Abudula Aihaitijiang | Research Square (Research Square)

<title>Abstract</title> This article introduces a new class of soft aerial robots and methods to deform their fuselage to achieve high-performance fixed-wing flight. Body morphing is used commonly in nature for … <title>Abstract</title> This article introduces a new class of soft aerial robots and methods to deform their fuselage to achieve high-performance fixed-wing flight. Body morphing is used commonly in nature for mobility and maneuverability. However, despite significant interest in morphing wings, aerial robotics research has not explored the use of a morphing fuselage. Current winged aerial robots still lack the ability to adapt to different ﬂight conditions and tasks, which may require high-maneuverability, sharp turns, aggressive flight, or vertical take-off and landing capabilities. Here, we describe an origami-inspired morphing fuselage strategy to improve the agility, turn maneuverability, and extended fixed-wing flight capabilities of a new class of flight platform called soft aerial robot (SoAR). We experimentally demonstrate that SoAR can extend flight capabilities by simply changing its body bending curvature in the horizontal and vertical planes during flight. Horizontal bending of the fuselage results in a rapid sharp-turn maneuver. Vertical up-bending of the fuselage results in aggressive pull-up flight capabilities and a unique emergency brake maneuver. The proposed morphing-fuselage soft aerial robot enables grasping and delivery of objects by changing the body length. Finally, the deformable structure of the fuselage helps absorb external forces to protect the aerial robot from collisions.

Mechanical Metamaterial‐Based Structure with Magnetically Controlled Nonreversibility and Nonreciprocity for Programmable Locomotion

2025-06-19

Krzysztof K. Dudek , Olly Duncan , Julio Andrés Iglesias Martínez +1 more | Advanced Science

Abstract Programmable mechanical metamaterials hold the key to critical innovations in materials science research, by harnessing relatively unexplored nonlinearities that change effective responses. Effective properties of a metamaterial strongly depend … Abstract Programmable mechanical metamaterials hold the key to critical innovations in materials science research, by harnessing relatively unexplored nonlinearities that change effective responses. Effective properties of a metamaterial strongly depend on the reversibility of the deformation process. While most elastic materials show reciprocity and reversibility, the possibility of concurrently observing nonreciprocity, defined as a deformation that is not mirrored when a body is loaded equally from opposite sides, as well as a nonreversible deformation process, opens doors to addressing complex mechanical problems that are crucial from the perspective of soft body dynamics. In this work, a magneto‐mechanical metamaterial‐based structure is proposed that simultaneously exhibits both of these phenomena by utilizing elastic and magnetically induced nonlinearities. It is shown that such a system can undergo a transition in its static mechanical properties, such as Poisson's ratio and stiffness, leading to stark changes in energy absorption. It is also demonstrated that, thanks to the asymmetric distribution of magnetic inclusions, the entire structure can exhibit an efficient locomotion mechanism suitable for applications in robotics.

Bi-stable boxed thick origami-inspired modular and load-carrying structures

2025-06-19

Haonan Wang , Zhuangzhi Miao , Jing Lv +3 more | Mechanism and Machine Theory

Research on the optimization design method of origami-type thin-walled pipes filled with gradient polyurethane foam

2025-06-18

Yong Xiao , Haiyang Gao , Qianwen Wu +3 more | Mechanics of Advanced Materials and Structures

Soft origami tripod based on electrohydraulic actuator for twisting motion

2025-06-18

Sohyun Kim , Joohyeon Kang , Seunghoon Yoo +1 more | Sensors and Actuators A Physical

Impact of inertial and nonlinear damping effects on the strain-induced domain wall motion in bilayer composite structure

2025-06-18

Sarabindu Dolui , Ambalika Halder , Saketh Kurumaddali +1 more | International Journal of Engineering Science

Surface Wrinkling of Plasma‐Exposed PDMS is Caused by Water Vapor Sorption: An Optical Environmental Sensor

2025-06-18

Zain Ahmad , Gunjan Tyagi , Shuning Xiang +6 more | Advanced Functional Materials

Abstract Wrinkling of polydimethylsiloxane (PDMS) has unlocked a plethora of technological applications, from tunable surface wetting to photonic response. Surface undulations with prescribed wavelength and amplitude are excited by in‐plane … Abstract Wrinkling of polydimethylsiloxane (PDMS) has unlocked a plethora of technological applications, from tunable surface wetting to photonic response. Surface undulations with prescribed wavelength and amplitude are excited by in‐plane mechanical compression of bilayers comprising a thin, stiff outer skin on a soft elastomer or gel. Plasma oxidation has become ubiquitous for creating such thin (≈10 nm) glassy interfacial layers. Spontaneous wrinkling can occur even in the absence of external mechanical strain fields, which has been rationalized in terms of a thermally‐induced strain that accompanies the expansion‐contraction cycle of such laminate films. It is shown that exposure to water vapor is, instead, responsible for surface wrinkling, due to the swelling the oxidized skin layer. This interpretation of surface wrinkling provides a rationale for the apparent experimental variability of the wrinkling process. This hypothesis is verified experimentally by observing and modelling the spatiotemporal evolution of the reversible wrinkling process under a range of controlled environmental conditions. From a practical standpoint, it is found that this effect provides for a facile approach for humidity sensing through structural color changes arising from the diffractive wrinkled skin.

Terrestrial locomotion of microscopic robots enabled by 3D nanomembranes with nonreciprocal shape morphing

2025-06-17

Yang Wang , Xing Li , Chang Liu +7 more | Proceedings of the National Academy of Sciences

Microscopic robots exhibit efficient locomotion in liquids by leveraging fluid dynamics and chemical reactions to generate force asymmetry, thereby enabling critical applications in photonics and biomedicine. However, achieving controllable locomotion … Microscopic robots exhibit efficient locomotion in liquids by leveraging fluid dynamics and chemical reactions to generate force asymmetry, thereby enabling critical applications in photonics and biomedicine. However, achieving controllable locomotion of such robots on terrestrial surfaces remains challenging because fluctuating adhesion on nonideal surfaces disrupts the necessary asymmetry for propulsion. Here, we present a microscopic robot composed of three-dimensional nanomembranes, which navigate diverse terrestrial surfaces with omnidirectional motion. We propose a general mechanism employing nonreciprocal shape morphing to generate stable asymmetric forces on surfaces. This nonreciprocal shape morphing is realized through a laser-actuated vanadium dioxide nanomembrane, leveraging the material's inherent hysteresis properties. We demonstrate that these robots can be fabricated in various shapes, ranging from simple square structures to bioinspired "bipedal" helical designs, enabling them to directionally navigate challenging surfaces such as paper, leaves, sand, and vertical walls. Furthermore, their omnidirectional motion facilitates applications in microassembly and microelectronic circuit integration. Additionally, we developed an artificial intelligence control algorithm based on reinforcement learning, enabling these robots to autonomously follow complex trajectories, such as tracing the phrase "hello world". Our study lays a theoretical and technological foundation for microscopic robots with terrestrial locomotion and paves a way for microscopic robots capable of operating on surfaces for advanced nanophotonic, microelectronic, and biomedical applications.

Pneumatic Soft Actuator Based On Origami Structure

2025-06-17

Jun Yang , Xin Dong , Changyang Huang +2 more | Journal of Pressure Vessel Technology

Abstract In order to improve the deformability of the actuator, this paper proposes a pneumatic soft actuator based on origami structure. The structural design of the actuator, theoretical analysis and … Abstract In order to improve the deformability of the actuator, this paper proposes a pneumatic soft actuator based on origami structure. The structural design of the actuator, theoretical analysis and validation, the influence of parameters on the output characteristics, the manufacturing process are described in detail, and finally, an experimental platform was built based on the actual actuator that was fabricated, and the splaying angle and output torque of the actuator were tested. The actuator has a splaying angle of up to 102° at an input pressure of 3.0 KPa, and an output torque of 0.387 N/mm per unit area at an initial splaying angle and an input pressure of 6.0 KPa. The results show that compared to folded and non-folded actuators, the deformation of the origami actuator in this article mainly relies on the large folding ratio of the origami structure itself rather than the characteristics of the material, so it possesses deformability and larger output torque, effectively solving the issues of poor deformability and low output torque the soft actuator, and it has a good application prospect .The device improves the portability and functionality of the soft drive by means of a pre-designed folding structure that achieves a large folding ratio when inflated. In addition, it can provide a certain torque while avoiding the risk of impact on rigid machinery, and can be used for clamping and pressing of fragile items. The device provides new structural implications for soft drives and actuators.

Inferring Spatially Varying Bending Stiffness of Biopolymers with Deep-Learning Approach

2025-06-17

C.C. Hong , Chan Lim , Jaeho Oh +5 more | bioRxiv (Cold Spring Harbor Laboratory)

The bendability of biopolymers, including DNA, actin filaments, and microtubules, is crucial to diverse biological processes, such as cell motility and cytoskeletal organization. While conventional polymer models like the worm-like … The bendability of biopolymers, including DNA, actin filaments, and microtubules, is crucial to diverse biological processes, such as cell motility and cytoskeletal organization. While conventional polymer models like the worm-like chain model assume uniform bending stiffness along the contour, biopolymers in reality often attain spatially varying bending stiffness as a result of complex cellular interactions. For instance, the bending stiffness of actin filaments and microtubules varies in response to associated binding proteins or chemical modifications. Despite its biological implications, measuring the position-dependent persistence length along polymer contours remains challenging. Here, we present a deep-learning-based method that quantitatively predicts spatially varying bending stiffness of biopolymers. Our framework segments a polymer chain into short overlapping fragments, predicts local persistence lengths using a deep-learning model, and reconstructs full profiles. Using simulated data, we demonstrate that our approach achieves high accuracy and robustness even under data-scarce conditions. Applied to various biological systems, our method reveals a spatially varying stiffness from tip to base in filopodia as well as spatially heterogeneous stiffness in microtubules. Additionally, we investigate the internal mechanism of our deep-learning model and show that the model utilizes multiple physics-related features for persistence length estimation while adaptively adjusting its attention based on polymer stiffness.

Amyloid Folding: an Origami-Based Approach

2025-06-17

Luís Maurício T. R. Lima | bioRxiv (Cold Spring Harbor Laboratory)

Amyloid is an ordered folding pattern that involves a cross-beta arrangement, with hydrogen-bonding between adjacent chains in the fiber elongation axis, and side-chain interactions perpendicular to it, forming steric and/or … Amyloid is an ordered folding pattern that involves a cross-beta arrangement, with hydrogen-bonding between adjacent chains in the fiber elongation axis, and side-chain interactions perpendicular to it, forming steric and/or polar zippers intra- and/or inter-chains. The arrangement of the polypeptide backbone and the side-chain interactions can be arranged with different morphologies that are repeated along the fiber growth axis as stacking units. A simple representation of amyloid folding of proteins using paper origami is reported here, which can be used to visualize the β-sheet along fiber axis and the perpendicular variability in topological arrangement. The model uses regular office paper, in the form of multiple linearized polypeptide chains, arranged in parallel or anti-parallel forms, connected by hydrogen bonds. Alternating mountain/valley creases along the growth axis of the fibrils and, over the front/back side-chains, results in a pleated sheet that can be used to study the topological arrangement of amyloid fibrils and the polar/steric zippers. The present models can be used as teaching tools for understanding the structural and molecular basis of amyloid folding, chain growth, homo- and cross-seeding, and other features of amyloid function in health, disease and biotechnology.

Interfacial Dynamics and Mechanical Properties of Substrate-Supported [<i>c</i>2]Daisy Chain Networks

2025-06-17

Yang Wang , Guoquan Liu , Zhaoming Zhang +2 more | Macromolecules

Active Fabric Origami Enabled by Digital Embroidery of Magnetic Yarns.

2025-06-17

Haiqiong Li , Han Zhang , Xiang‐Jun Zha +1 more | PubMed

Active fabrics can perform deformations such as contraction, expansion, and bending when exposed to external stimuli. Origami, the ancient art of paper folding, transforms a 2D sheet into a complex … Active fabrics can perform deformations such as contraction, expansion, and bending when exposed to external stimuli. Origami, the ancient art of paper folding, transforms a 2D sheet into a complex 3D structure. However, integrating origami-inspired designs into active fabrics presents significant challenges, including the large-scale production of stimuli-responsive yarns that can be processed using standard textile techniques to achieve intricate origami patterns with high precision and versatility. In this work, the large-scale fabrication of magnetic yarns featuring high magnetic susceptibility, mechanical strength, and flexibility is reported, which is enabled by processing magnetic polymer composites with a series of textile engineering processes. Utilizing digital embroidery, these magnetic yarns are programmed into origami patterns with predefined yarn alignments on flexible fabrics to create various active fabric origami structures that are mechanical durable and functional consistent. These structures can reversibly transform among shapes in response to specific magnetic fields, enabling a range of functionalities such as altering surface roughness, delivering linear actuation, mimicking flower blooming, and providing switchable thermal insulation. The novel active fabric origami provides promising smart platforms across areas as diverse as smart textiles, soft robotics, wearable devices, and fashion.

Stretchable and Flexible Crystalline Silicon Photovoltaic Modules Embodying an Auxetic Rotating‐Square Structure for Adjustable Transmittance

2025-06-17

Chen Cao , Tasmiat Rahman , Stuart A. Boden | Progress in Photovoltaics Research and Applications

ABSTRACT This work describes the segmentation of commercial crystalline silicon solar cells into smaller sections and their subsequent restructuring into interconnected arrays, based on an auxetic rotating‐square architecture, to produce … ABSTRACT This work describes the segmentation of commercial crystalline silicon solar cells into smaller sections and their subsequent restructuring into interconnected arrays, based on an auxetic rotating‐square architecture, to produce a lightweight, flexible and stretchable solar module. As expected, the sectioning of the solar cells reduces their power conversion efficiency due to increased carrier recombination at the sawn edges. However, average cell section efficiencies are shown to be less than 1.8% lower than the original cells. Output voltage and current can be tailored according to the combination of series or parallel connections between solar cell sections in the design. Due to the negative Poisson's ratio of the auxetic structure, bidirectional expansion with uniaxial stretching is achieved, opening gaps in the module, which allows the light transmittance to be adjusted. Mechanical tests reveal that the structures are robust to repeated cycles of expansion and relaxation, aided by the joint rotation mechanism of expansion that avoids excessive strain on the joint material. The modules are fully expanded when each cell section is rotated by 45°. In this expanded state, modules made of 31.75 mm × 31.75 mm solar cell sections have a strain of 67% and transmittance of 41.9%. Modules incorporating the smaller 20 mm × 20 mm cell sections have a maximum strain of 60%, with a corresponding transmittance of 49.5%. A geometric model is used to show that by varying the design parameters, the transmittance maximum, minimum and range can be tuned, opening up various potential applications that include BIPV (e.g., partially shaded windows), AgriPV (e.g., greenhouse roofs), portable PV devices and wearables.

Bioinspired Moisture-Responsive Smart Knitted Fabric with Artificial Leaf Stomata Based on Polyacrylamide Hydrogel

2025-06-16

Yueyun Yu , Qing Chen , Bomou Ma +3 more | ACS Applied Materials & Interfaces

Dynamic moisture-responsive textiles are highly desirable for smart clothing that adapts to physiological and environmental changes to enhance the wearer's comfort. Unfortunately, many moisture-responsive fabrics suffer from slow response times, … Dynamic moisture-responsive textiles are highly desirable for smart clothing that adapts to physiological and environmental changes to enhance the wearer's comfort. Unfortunately, many moisture-responsive fabrics suffer from slow response times, poor reversibility, and insufficient durability. Moreover, these fabrics frequently fail to satisfy requirements such as tactile softness, appearance retention, and integration compatibility with existing clothing systems. This research reports a commercial strategy to engineer artificial leaf stomata into knitted fabrics by using screen-printed polyacrylamide (PAAm) hydrogel coatings followed by laser cutting. Inspired by natural stomatal function, our design enables the fabric to autonomously open and close moisture-responsive slits without altering its surface appearance or tactile properties. By investigating the hydrogel formulation, coating and cutting direction, and aspect ratio of the pattern, we optimized the actuation performance. Fabrics coated with 0.12 wt % cross-linked PAAm showed rapid and reversible opening behavior: slits cut along the weft direction at an 8:9 aspect ratio reached a maximum width of 1.07 ± 0.01 mm, while those at the warp direction at 7:9 reached 0.80 ± 0.04 mm. Upon absorbing moisture equivalent to 95% of their dry weight, slits opened within 10 s, increasing air permeability by 63.3% compared to control fabrics. The pores remained stable after repeated laundering. Under wet conditions, the slits enhanced heat and moisture dissipation, keeping the skin drier. This bioinspired integration of moisture actuation into textiles offers a promising route toward high-performance, moisture-responsive garments with durability.

Preliminary Design of a SMA Bending Vortex Generator

2025-06-16

Salvatore Ameduri , Bernardino Galasso , Antonio Concilio +3 more | Advances in transdisciplinary engineering

The paper introduces the preliminary activities carried out within the RADAR project (ContRollo Attivo Del flusso AeRdinamico, in Italian, or Active Control of the Aerodynamic Flow), funded by the (Italian) … The paper introduces the preliminary activities carried out within the RADAR project (ContRollo Attivo Del flusso AeRdinamico, in Italian, or Active Control of the Aerodynamic Flow), funded by the (Italian) Aerospace Research Program (PRORA), DM 662. Its main objective is to enhance the aerodynamic efficiency of a small-medium range aircraft through turbulent flow control techniques, for the environmental impact alleviation in terms of both gas and acoustic emissions. A key innovation involves the design of an adaptive vortex generator to mitigate tip stall and facilitate span-wise load control operations. This concept entails a compact metallic plate, flush with the wing skin if stowed, and a Shape Memory Alloy (SMA) active layer, enabling plate deflection upon heating, and consequently modifying the aerodynamic field. The study herein reported presents a theoretical framework for the preliminary modeling of a 2-layer SMA bending plate. The approach is based on: momentum equilibrium between the SMA actuator and an aluminum plate working as elastic recovery element; stress-induced SMA phase transformation by bending loads. The behavior of the SMA plate is described through the elastic line equation, formulated in terms of deflection angle versus the curvilinear abscissa (wide deflection range). Additionally, by knowing the constitutive law of the SMA material, the resulting load-unload curves for the SMA are computed in terms of applied moment vs resulting deflection at various temperatures. These curves are then compared to the moment-deflection profile of the antagonistic elastic aluminum plate. Under specific assumptions herein adopted, the diagram allows to identify specific points representing the pre-load/ stowed condition of the vortex generator device, and its fully deployed configuration.

Magnetic Soft Actuators: Sensor‐Actuator Fusion via Integrated Fabrication for Precise Control

2025-06-14

Xingxiang Li , Boxi Sun , Dongxiao Li +3 more | Advanced Materials Technologies

Abstract Magnetic soft actuators (MSAs) represent a paradigm shift in robotics, offering wireless control, biocompatibility, and adaptability through magnetic field‐driven deformation. However, integrating sensing and actuation in MSAs presents significant … Abstract Magnetic soft actuators (MSAs) represent a paradigm shift in robotics, offering wireless control, biocompatibility, and adaptability through magnetic field‐driven deformation. However, integrating sensing and actuation in MSAs presents significant challenges due to their miniaturized scale, material heterogeneity, and complex manufacturing requirements. Traditional robotic systems benefit from modular design and standardized integration of discrete components, but MSAs require a co‐design approach where sensing and actuation functionalities are embedded within a single compliant structure. This review systematically examines recent advances in MSAs across four key areas: actuation, sensing, control, and manufacturing technologies. The critical role of material‐structure co‐design and integrated fabrication is emphasized in bridging the gap between laboratory innovation and real‐world deployment, highlighting pathways for advancing the practical implementation of magnetic soft actuators.

Flat or crumpled: States of active symmetric membranes

2025-06-13

NULL AUTHOR_ID | Physical review. E

Growth laws and universality in 2-tips: Microscopic and coarse grained approach

2025-06-13

NULL AUTHOR_ID | Physical review. E

Multi-responsive Itaconic Acid-based Polymer toward Regulatable Patterning Surfaces and Rewritable Information Storage Applications

2025-06-13

Haochen Guo , Jian Chen , Bang Feng +6 more | Chinese Journal of Polymer Science

Free and forced vibrations of FG graphene origami-enabled auxetic metamaterial annular sector plates employing variational differential quadrature approach

2025-06-13

A. Mirsabetnazar , R. Ansari , M. Zargar Ershadi +1 more | International Journal of Structural Stability and Dynamics

Full‐Spectrum Tunable and Handedness Invertible Geometric Phase Elements in Nanomotor‐based Spiral Superstructures

2025-06-13

Ching‐Han Yang , Anup Kumar Sahoo , Yun-Hwei Shen +2 more | Advanced Optical Materials

Abstract Photon‐based communications can remarkably expand information capacity due to their multidimensional physical properties, including amplitude, polarization, wavelength, and angular momentum. To manipulate light's properties, traditional static/bulky optical elements such … Abstract Photon‐based communications can remarkably expand information capacity due to their multidimensional physical properties, including amplitude, polarization, wavelength, and angular momentum. To manipulate light's properties, traditional static/bulky optical elements such as lenses, waveplates, holograms rely on the propagation effect to control phase of light. Ultrathin, multifunctional optical elements driven by miniaturization and system integration in the production of photonic devices are urgently needed. This study employs a micropatterned photoalignment technology to fabricate a series of beam‐shaping‐related planar chiro‐optical geometric phase elements (GPEs) based on nanomotor‐based cholesteric liquid crystals (CLCs). When the incident light's wavelength falls within the photonic bandgap (PBG) of the CLCs, the reflected beam acquires a spatially distributed phase modulation determined by the micropatterned CLC directors on the element substrate. This phenomenon, associated with Pancharatnam–Berry geometric phase, enables full 2π phase control of light. Through the unique photoisomerization‐induced chirality‐reversal property of nanomotors, continuous, reversible full‐spectrum PBG tuning and reversible switching of handedness can be achieved for each GPE. This work demonstrates both the design rule and experimental realization of advanced planar optical elements with advantages over traditional static/bulky devices. Importantly, it provides guidance for future efforts to achieve complete dimensional control of light in self‐organizing nanomotor‐based soft‐matter devices.

DNN-Augmented Kinematically Decoupled Three-DoF Origami Parallel Robot for High-Precision Heave and Tilt Control

2025-06-13

Gaokun Shi , Hassen Nigatu , Zhijian Wang +1 more | Actuators

This paper presents a three-degrees-of-freedom origami parallel robot that is free from parasitic motion. This robot is designed to achieve one translational and two rotational motions within its workspace, enabling … This paper presents a three-degrees-of-freedom origami parallel robot that is free from parasitic motion. This robot is designed to achieve one translational and two rotational motions within its workspace, enabling precise orientation about a fixed point—a capability unattainable for parallel robots with parasitic motion. The elimination of parasitic motion is critical, allowing the use of this device in applications requiring high precision. The robot’s key kinematic features include a parasitic motion-free workspace, large orientational capability, compactness, decoupled motion, simplicity in manufacturing and control, mechanically pivoted rotation of the moving platform, and scalability. These characteristics make the robot particularly well-suited for micromanipulation tasks in both manufacturing and medical applications. In manufacturing, it can enable high-precision operations such as micro-assembly, optical fiber alignment, and semiconductor packaging. In medicine, it can support delicate procedures such as microsurgery and cell injection, where sub-micron accuracy, high stability, and precise motion decoupling are critical requirements. The use of nearly identical limbs simplifies the architecture, facilitating easier design, manufacture, and control. The kinematics of the robot is analyzed using reciprocal screw theory for an analytic constraint-embedded Jacobian. To further enhance operational accuracy and robustness, particularly in the presence of uncertainties or disturbances, a deep neural network (DNN)-based state estimation method is integrated, providing accurate forward kinematic predictions. The construction of the robot utilizes origami-inspired limbs and joints, enhancing miniaturization, manufacturing simplicity, and foldability. Although capable of being scaled up or further miniaturized, its current size is 66 mm × 68 mm × 100 mm. The robot’s moving platform is theoretically and experimentally proven to be free of parasitic motion and possesses a large orientation capability. Its unique features are demonstrated, and its potential for high-precision applications is thoroughly discussed.

Experimental and Numerical Investigation of Thermally Activated Shape-Morphing in 4D-Printed ABS Beams

2025-06-12

G. Kostopoulos , Stelios K. Georgantzinos | Research Square (Research Square)

<title>Abstract</title> This study investigates the thermally induced shape-morphing behavior of 4D-printed beams fabricated from Acrylonitrile Butadiene Styrene (ABS) using fused deposition modeling (FDM). A comprehensive experimental methodology was employed to … <title>Abstract</title> This study investigates the thermally induced shape-morphing behavior of 4D-printed beams fabricated from Acrylonitrile Butadiene Styrene (ABS) using fused deposition modeling (FDM). A comprehensive experimental methodology was employed to examine the influence of key process parameters—namely printing speed, layer height, layer width, nozzle temperature, and activation temperature—on the deformation characteristics of the printed structures. A Taguchi design of experiments was combined with signal-to-noise (<italic>S/N</italic>) ratio analysis and analysis of variance (ANOVA) to identify optimal parameter settings and quantify their statistical significance. Empirical analytical models were proposed through multiple linear regression to describe the relationships between process parameters and shape-morphing responses. To complement the experimental analysis, a finite element model was developed, incorporating layer-specific coefficients of thermal expansion (<italic>CTE</italic>s) to simulate the differential thermal contraction across the printed layers. Comparison between simulated and experimental results showed good agreement, validating the modeling approach. The integrated experimental–statistical–numerical framework presented in this work provides practical insights for optimizing shape-morphing behavior in 4D-printed thermoplastic structures and demonstrates the potential of ABS as a viable material for time-responsive applications.

Electro-humidity responsive soft actuators based on cellulose nanofibers-nanocrystals for bioinspired applications

2025-06-12

Fan Wang , Ruibin Qi , Yujiao Wu +3 more | Science China Technological Sciences

Materials Evolution by Programmed Twisting: a DNA‐Inspired Ultrastrong Supercoiled Conformational Fiber for Energy‐Storage and Buffering

2025-06-12

Ziyu Zhao , Jiarui Yang , Wenrui Cai +7 more | Advanced Materials

Abstract The conformational folding/unfolding behaviors of DNA supercoils serve as a fundamental mechanism governing ultradense bio‐information storage and precise genetic transcription. Mimicking those nanoscale dynamic conformational behaviors for macroscopic materials … Abstract The conformational folding/unfolding behaviors of DNA supercoils serve as a fundamental mechanism governing ultradense bio‐information storage and precise genetic transcription. Mimicking those nanoscale dynamic conformational behaviors for macroscopic materials to achieve unusual functionalities will be of great interest but remains unexplored. Herein, a DNA‐inspired materials evolution paradigm is presented to create multifunctional supercoiled conformational fibers (SCFs) by programmed twisting controlled self‐buckling. Through the programmed twist‐stress modulation, a low‐density polyethylene strip is transformed into high‐performance DNA‐like SCF through a unique multiscale microstructure evolution process. This DNA‐like SCF exhibits five hallmark characteristics unattainable before, including ultra‐large elastic deformability (900 ± 50%), metal‐level mechanical strength (330 ± 30 MPa), unprecedented torsional energy‐storage density (16.1 ± 0.6 kJ kg −1 ), torsional energy release upon appropriate stimulations, and impact buffering through conformation‐mediated energy‐dissipation. Characterization reveals that these unexpected energy‐related properties mainly are contributed by the multiscale twisting‐reinforced microstructures and conformation mechanics. Potential applications of the SCFs are demonstrated finally by harvest‐and‐storage of wind energy and soft‐landing. The DNA‐like SCFs indicate a general platform for materials evolution with extraordinary mechanics and functions.

Electric Field Driven Soft Morphing Matter

2025-06-12

Ciqun Xu , Charl F. J. Faul , Majid Taghavi +1 more | Advanced Materials

Abstract The manipulation of soft morphing robots using external electric fields and wireless control is challenging. Electric field‐driven soft morphing matter, termed electro‐morphing gel (e‐MG), that exhibits complex multimodal large‐scale … Abstract The manipulation of soft morphing robots using external electric fields and wireless control is challenging. Electric field‐driven soft morphing matter, termed electro‐morphing gel (e‐MG), that exhibits complex multimodal large‐scale deformation (showing up to 286% strain, and strain rates up to 500% s −1 ) and locomotion under external electric fields applied using compact and lightweight electrodes is presented. The distinctive capabilities of e‐MG derive from the combination of an elastomeric matrix and nanoparticulate paracrystalline carbon. The material properties, electroactive principle, and control strategies are explored and demonstrate fundamental morphing matter behaviors including rotating, translating, stretching, spreading, bending, and twisting. A range of potential bio‐inspired applications, including slim mold‐like spreading, snail‐like jumping over a gap, object transport, wall climbing, and a frog tongue‐inspired gripper is shown. The e‐MG provides morphing capabilities beyond the current limitations in wireless control for a wide range of applications in soft and bio‐inspired robotics, dexterous manipulation, and space exploration.