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Skillin NP, Bauman GE, Kirkpatrick BE, McCracken JM, Park K, Vaia RA, Anseth KS, White TJ. Photothermal Actuation of Thick 3D-Printed Liquid Crystalline Elastomer Nanocomposites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2313745. [PMID: 38482935 DOI: 10.1002/adma.202313745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/28/2024] [Indexed: 03/27/2024]
Abstract
Liquid crystalline elastomers (LCEs) are stimuli-responsive materials that transduce an input energy into a mechanical response. LCE composites prepared with photothermal agents, such as nanoinclusions, are a means to realize wireless, remote, and local control of deformation with light. Amongst photothermal agents, gold nanorods (AuNRs) are highly efficient converters when the irradiation wavelength matches the longitudinal surface plasmon resonance (LSPR) of the AuNRs. However, AuNR aggregation broadens the LSPR which also reduces photothermal efficiency. Here, the surface chemistry of AuNRs is engineered via a well-controlled two-step ligand exchange with a monofunctional poly(ethylene glycol) (PEG) thiol that greatly improves the dispersion of AuNRs in LCEs. Accordingly, LCE-AuNR nanocomposites with very low PEG-AuNR content (0.01 wt%) prepared by 3D printing are shown to be highly efficient photothermal actuators with rapid response (>60% strain s-1) upon irradiation with near-infrared (NIR; 808 nm) light. Because of the excellent dispersion of PEG-AuNR within the LCE, unabsorbed NIR light transmits through the nanocomposites and can actuate a series of samples. Further, the dispersion also allows for the optical deformation of millimeter-thick 3D printed structures without sacrificing actuation speed. The realization of well-dispersed nanoinclusions to maximize the stimulus-response of LCEs can benefit functional implementation in soft robotics or medical devices.
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Affiliation(s)
- Nathaniel P Skillin
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
- Medical Scientist Training Program, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Grant E Bauman
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Bruce E Kirkpatrick
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
- Medical Scientist Training Program, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Joselle M McCracken
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Kyoungweon Park
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH, 45433, USA
- UES, Inc., Dayton, OH, 45433, USA
| | - Richard A Vaia
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH, 45433, USA
| | - Kristi S Anseth
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO, 80303, USA
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Zhang J, Zhang Y, Yang J, Wang X. Beyond Color Boundaries: Pioneering Developments in Cholesteric Liquid Crystal Photonic Actuators. MICROMACHINES 2024; 15:808. [PMID: 38930778 PMCID: PMC11205596 DOI: 10.3390/mi15060808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/09/2024] [Accepted: 06/17/2024] [Indexed: 06/28/2024]
Abstract
Creatures in nature make extensive use of structural color adaptive camouflage to survive. Cholesteric liquid crystals, with nanostructures similar to those of natural organisms, can be combined with actuators to produce bright structural colors in response to a wide range of stimuli. Structural colors modulated by nano-helical structures can continuously and selectively reflect specific wavelengths of light, breaking the limit of colors recognizable by the human eye. In this review, the current state of research on cholesteric liquid crystal photonic actuators and their technological applications is presented. First, the basic concepts of cholesteric liquid crystals and their nanostructural modulation are outlined. Then, the cholesteric liquid crystal photonic actuators responding to different stimuli (mechanical, thermal, electrical, light, humidity, magnetic, pneumatic) are presented. This review describes the practical applications of cholesteric liquid crystal photonic actuators and summarizes the prospects for the development of these advanced structures as well as the challenges and their promising applications.
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Affiliation(s)
- Jinying Zhang
- Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China; (Y.Z.); (J.Y.); (X.W.)
- Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing 314001, China
| | - Yexiaotong Zhang
- Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China; (Y.Z.); (J.Y.); (X.W.)
| | - Jiaxing Yang
- Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China; (Y.Z.); (J.Y.); (X.W.)
| | - Xinye Wang
- Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China; (Y.Z.); (J.Y.); (X.W.)
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Mihai LA, Mistry D, Raistrick T, Gleeson HF, Goriely A. A mathematical model for the auxetic response of liquid crystal elastomers. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210326. [PMID: 36031830 PMCID: PMC9421376 DOI: 10.1098/rsta.2021.0326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/20/2022] [Indexed: 06/15/2023]
Abstract
We develop a mathematical model that builds on the surprising nonlinear mechanical response observed in recent experiments on nematic liquid crystal elastomers. Namely, under uniaxial tensile loads, the material, rather than thinning in the perpendicular directions, becomes thicker in one direction for a sufficiently large strain, while its volume remains unchanged. Motivated by this unusual large-strain auxetic behaviour, we model the material using an Ogden-type strain-energy function and calibrate its parameters to available datasets. We show that Ogden strain-energy functions are particularly suitable for modelling nematic elastomers because of their mathematical simplicity and their clear formulation in terms of the principal stretches, which have a direct kinematic interpretation. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.
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Affiliation(s)
- L. Angela Mihai
- School of Mathematics, Cardiff University, Cardiff CF24 4AG, UK
| | - Devesh Mistry
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas Raistrick
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Helen F. Gleeson
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
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Ding A, Lee SJ, Tang R, Gasvoda KL, He F, Alsberg E. 4D Cell-Condensate Bioprinting. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202196. [PMID: 35973946 PMCID: PMC9463124 DOI: 10.1002/smll.202202196] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/20/2022] [Indexed: 05/31/2023]
Abstract
4D bioprinting techniques that facilitate formation of shape-changing scaffold-free cell condensates with prescribed geometries have yet been demonstrated. Here, a simple 4D bioprinting approach is presented that enables formation of a shape-morphing cell condensate-laden bilayer system. The strategy produces scaffold-free cell condensates which morph over time into predefined complex shapes. Cell condensate-laden bilayers with specific geometries are readily fabricated by bioprinting technologies. The bilayers have tunable deformability and microgel (MG) degradation, enabling controllable morphological transformations and on-demand liberation of deformed cell condensates. With this system, large cell condensate-laden constructs with various complex shapes are obtained. As a proof-of-concept study, the formation of the letter "C"- and helix-shaped robust cartilage-like tissues differentiated from human mesenchymal stem cells (hMSCs) is demonstrated. This system brings about a versatile 4D bioprinting platform idea that is anticipated to broaden and facilitate the applications of cell condensation-based 4D bioprinting.
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Affiliation(s)
- Aixiang Ding
- The Institute of Flexible Electronics (IFE, Future Technologies), Xiamen University, Xiamen, 361005, China
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 909 S Wolcott Ave, Chicago, IL, 60612, United States
| | - Sang Jin Lee
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 909 S Wolcott Ave, Chicago, IL, 60612, United States
| | - Rui Tang
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 909 S Wolcott Ave, Chicago, IL, 60612, United States
| | - Kaelyn L Gasvoda
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 909 S Wolcott Ave, Chicago, IL, 60612, United States
| | - Felicia He
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 909 S Wolcott Ave, Chicago, IL, 60612, United States
| | - Eben Alsberg
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 909 S Wolcott Ave, Chicago, IL, 60612, United States
- Departments of Mechanical & Industrial Engineering, Orthopaedics, and Pharmacology and Regenerative Medicine, University of Illinois at Chicago, 909 S. Wolcott Ave., Chicago, IL, 60612, USA
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Zhang Y, Zhang C, Wang R, Tan W, Gu Y, Yu X, Zhu L, Liu L. Development and challenges of smart actuators based on water-responsive materials. SOFT MATTER 2022; 18:5725-5741. [PMID: 35904079 DOI: 10.1039/d2sm00519k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Water-responsive (WR) materials, due to their controllable mechanical response to humidity without energy actuation, have attracted lots of attention to the development of smart actuators. WR material-based smart actuators can transform natural humidity to a required mechanical motion and have been widely used in various fields, such as soft robots, micro-generators, smart building materials, and textiles. In this paper, the development of smart actuators based on different WR materials has been reviewed systematically. First, the properties of different biological WR materials and the corresponding actuators are summarized, including plant materials, animal materials, and microorganism materials. Additionally, various synthetic WR materials and their related applications in smart actuators have also been introduced in detail, including hydrophilic polymers, graphene oxide, carbon nanotubes, and other synthetic materials. Finally, the challenges of the WR actuator are analyzed from the three perspectives of actuator design, control methods, and compatibility, and the potential solutions are also discussed. This paper may be useful for the development of not only soft actuators that are based on WR materials, but also smart materials applied to renewable energy.
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Affiliation(s)
- Yiwei Zhang
- School of Automation and Electrical Engineering, Shenyang Ligong University, Shenyang 110159, Liaoning, China.
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
| | - Chuang Zhang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
| | - Ruiqian Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjun Tan
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanyu Gu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Xiaobin Yu
- School of Automation and Electrical Engineering, Shenyang Ligong University, Shenyang 110159, Liaoning, China.
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
| | - Lizhong Zhu
- School of Automation and Electrical Engineering, Shenyang Ligong University, Shenyang 110159, Liaoning, China.
| | - Lianqing Liu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
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6
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Singh H, Virga EG. A Ribbon Model for Nematic Polymer Networks. JOURNAL OF ELASTICITY 2022; 153:613-634. [PMID: 37293564 PMCID: PMC10244295 DOI: 10.1007/s10659-022-09900-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 05/09/2022] [Indexed: 06/10/2023]
Abstract
We present a theory of deformation of ribbons made of nematic polymer networks (NPNs). These materials exhibit properties of rubber and nematic liquid crystals, and can be activated by external stimuli of heat and light. A two-dimensional energy for a sheet of such a material has already been derived from the celebrated neo-classical energy of nematic elastomers in three space dimensions. Here, we use a dimension reduction method to obtain the appropriate energy for a ribbon from the aforementioned sheet energy. We also present an illustrative example of a rectangular NPN ribbon that undergoes in-plane serpentine deformations upon activation under an appropriate set of boundary conditions.
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Affiliation(s)
- Harmeet Singh
- Laboratory for Computation and Visualization in Mathematics and Mechanics, Institute of Mathematics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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Shi J, Xu L, Qiu D. Effective Antifogging Coating from Hydrophilic/Hydrophobic Polymer Heteronetwork. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200072. [PMID: 35285176 PMCID: PMC9109053 DOI: 10.1002/advs.202200072] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/21/2022] [Indexed: 05/20/2023]
Abstract
Fogging on optical devices may severely impair vision, resulting in unacceptable adverse consequences. Hydrophilic coatings can prevent surface fogging by instantly facilitating pseudo-film water condensation but suffer from short antifogging duration due to water film thickening with further condensation. Here, an innovative strategy is reported to achieve longer antifogging duration via thickening the robust bonded hydrophilic/hydrophobic polymer heteronetwork coating to enhance its water absorption capacity. The combination of strong interfacial adhesion and hydrophilic/hydrophobic heteronetwork structure is key to this approach, which avoids interfacial failure and swelling-induced wrinkles under typical fogging conditions. The developed antifogging coating exhibits prolonged antifogging durations over a wide temperature range for repetitious usages. Eyeglasses coated with this coating successfully maintained fog-free vision in two typical scenarios. Besides, the coating recipes developed in this study also have potential as underwater glues as they demonstrate strong adhesions to both glass and polymer substrates in wet conditions.
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Affiliation(s)
- Junhe Shi
- Beijing National Laboratory for Molecular SciencesCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing100190China
- University of Chinese Academy of SciencesBeijing100049China
| | - Liju Xu
- Beijing National Laboratory for Molecular SciencesCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing100190China
| | - Dong Qiu
- Beijing National Laboratory for Molecular SciencesCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing100190China
- University of Chinese Academy of SciencesBeijing100049China
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8
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Light-Activated Elongation/Shortening and Twisting of a Nematic Elastomer Balloon. Polymers (Basel) 2022; 14:polym14061249. [PMID: 35335579 PMCID: PMC8953924 DOI: 10.3390/polym14061249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 02/04/2023] Open
Abstract
Nematic elastomer balloons with inflation-induced axial contraction and shear/torsion effect can be used as actuators for soft robots, artificial muscles, and biomedical instruments. The nematic elastomer can also generate drastic shape changes under illumination, and thus light can be utilized to activate the deformation of nematic elastomer balloons with huge advantages of being accurate, fast, untethered, and environmentally sustainable without chemical byproducts. To explore light-activated deformation behaviors of the balloon, a phenomenological relationship between light intensity and material parameters describing polymer backbone anisotropy is proposed from experiments, and a theoretical model of an optically-responsive nematic elastomer balloon is established based on the nematic elastomer theory. Various light-activated elongation/shortening and twisting behaviors in the cases of free-standing and axial-loading are presented and their mechanisms are elucidated. The light intensity and initial mesogen angle have great influences on the light-activated deformations including the radius, length, shearing angle and mesogen angle. Light can be easily controlled to trigger rich deformation processes, including elongation/shortening and torsion. The results of this paper are expected to promote the understanding of the light-activated deformation behaviors of the nematic elastomer balloon, and the applications in light-activated actuators and machines.
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9
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Vasileiadis T, Marchesi D’Alvise T, Saak CM, Pochylski M, Harvey S, Synatschke CV, Gapinski J, Fytas G, Backus EHG, Weil T, Graczykowski B. Fast Light-Driven Motion of Polydopamine Nanomembranes. NANO LETTERS 2022; 22:578-585. [PMID: 34904831 PMCID: PMC8796235 DOI: 10.1021/acs.nanolett.1c03165] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/15/2021] [Indexed: 06/12/2023]
Abstract
The actuation of micro- and nanostructures controlled by external stimuli remains one of the exciting challenges in nanotechnology due to the wealth of fundamental questions and potential applications in energy harvesting, robotics, sensing, biomedicine, and tunable metamaterials. Photoactuation utilizes the conversion of light into motion through reversible chemical and physical processes and enables remote and spatiotemporal control of the actuation. Here, we report a fast light-to-motion conversion in few-nanometer thick bare polydopamine (PDA) membranes stimulated by visible light. Light-induced heating of PDA leads to desorption of water molecules and contraction of membranes in less than 140 μs. Switching off the light leads to a spontaneous expansion in less than 20 ms due to heat dissipation and water adsorption. Our findings demonstrate that pristine PDA membranes are multiresponsive materials that can be harnessed as robust building blocks for soft, micro-, and nanoscale actuators stimulated by light, temperature, and moisture level.
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Affiliation(s)
- Thomas Vasileiadis
- Faculty
of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | | | - Clara-Magdalena Saak
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Mikolaj Pochylski
- Faculty
of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland
| | - Sean Harvey
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | | | - Jacek Gapinski
- Faculty
of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland
| | - George Fytas
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ellen H. G. Backus
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Tanja Weil
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Bartlomiej Graczykowski
- Faculty
of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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10
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Higueras-Ruiz DR, Nishikawa K, Feigenbaum H, Shafer M. What is an artificial muscle? A comparison of soft actuators to biological muscles. BIOINSPIRATION & BIOMIMETICS 2021; 17:011001. [PMID: 34792040 DOI: 10.1088/1748-3190/ac3adf] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
Interest in emulating the properties of biological muscles that allow for fast adaptability and control in unstructured environments has motivated researchers to develop new soft actuators, often referred to as 'artificial muscles'. The field of soft robotics is evolving rapidly as new soft actuator designs are published every year. In parallel, recent studies have also provided new insights for understanding biological muscles as 'active' materials whose tunable properties allow them to adapt rapidly to external perturbations. This work presents a comparative study of biological muscles and soft actuators, focusing on those properties that make biological muscles highly adaptable systems. In doing so, we briefly review the latest soft actuation technologies, their actuation mechanisms, and advantages and disadvantages from an operational perspective. Next, we review the latest advances in understanding biological muscles. This presents insight into muscle architecture, the actuation mechanism, and modeling, but more importantly, it provides an understanding of the properties that contribute to adaptability and control. Finally, we conduct a comparative study of biological muscles and soft actuators. Here, we present the accomplishments of each soft actuation technology, the remaining challenges, and future directions. Additionally, this comparative study contributes to providing further insight on soft robotic terms, such as biomimetic actuators, artificial muscles, and conceptualizing a higher level of performance actuator named artificial supermuscle. In conclusion, while soft actuators often have performance metrics such as specific power, efficiency, response time, and others similar to those in muscles, significant challenges remain when finding suitable substitutes for biological muscles, in terms of other factors such as control strategies, onboard energy integration, and thermoregulation.
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Affiliation(s)
- Diego R Higueras-Ruiz
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ-86011, United States of America
| | - Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ-86011, United States of America
| | - Heidi Feigenbaum
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ-86011, United States of America
| | - Michael Shafer
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ-86011, United States of America
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11
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Light-Responsive Soft Actuators: Mechanism, Materials, Fabrication, and Applications. ACTUATORS 2021. [DOI: 10.3390/act10110298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Soft robots are those that can move like living organisms and adapt to the surrounding environment. Compared with traditional rigid robots, the advantages of soft robots, in terms of material flexibility, human–computer interaction, and biological adaptability, have received extensive attention. Flexible actuators based on light response are one of the most promising ways to promote the field of cordless soft robots, and they have attracted the attention of scientists in bionic design, actuation implementation, and application. First, the three working principles and the commonly used light-responsive materials for light-responsive actuators are introduced. Then, the characteristics of light-responsive soft actuators are sequentially presented, emphasizing the structure strategy, actuation performance, and emerging applications. Finally, this review is concluded with a perspective on the existing challenges and future opportunities in this nascent research frontier.
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12
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Mihai LA, Wang H, Guilleminot J, Goriely A. Nematic liquid crystalline elastomers are aeolotropic materials. Proc Math Phys Eng Sci 2021; 477:20210259. [PMID: 35153581 PMCID: PMC8424302 DOI: 10.1098/rspa.2021.0259] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 08/04/2021] [Indexed: 11/12/2022] Open
Abstract
Continuum models describing ideal nematic solids are widely used in theoretical studies of liquid crystal elastomers. However, experiments on nematic elastomers show a type of anisotropic response that is not predicted by the ideal models. Therefore, their description requires an additional term coupling elastic and nematic responses, to account for aeolotropic effects. In order to better understand the observed elastic response of liquid crystal elastomers, we analyse theoretically and computationally different stretch and shear deformations. We then compare the elastic moduli in the infinitesimal elastic strain limit obtained from the molecular dynamics simulations with the ones derived theoretically, and show that they are better explained by including nematic order effects within the continuum framework.
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Affiliation(s)
- L Angela Mihai
- School of Mathematics, Cardiff University, Senghennydd Road, Cardiff CF24 4AG, UK
| | - Haoran Wang
- Department of Mechanical and Aerospace Engineering,Utah State University, Logan, UT 84322-4130, USA
| | - Johann Guilleminot
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708-0287, USA
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, UK
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13
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Abstract
Abstract
This article describes the defining characteristics of photochromic dyes and highlights the subset of properties that are of greatest commercial importance. It outlines the history of the industrial exploitation of photochromic colorants before moving on to discuss current and potential applications. In doing so, a brief tour of key types of photochromic dye is provided.
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14
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Bai R, Ocegueda E, Bhattacharya K. Photochemical-induced phase transitions in photoactive semicrystalline polymers. Phys Rev E 2021; 103:033003. [PMID: 33862748 DOI: 10.1103/physreve.103.033003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/26/2021] [Indexed: 11/07/2022]
Abstract
The emergent photoactive materials obtained through photochemistry make it possible to directly convert photon energy to mechanical work. There has been much recent work in developing appropriate materials, and a promising system is semicrystalline polymers of the photoactive molecule azobenzene. We develop a phase field model with two order parameters for the crystal-melt transition and the trans-cis photoisomerization to understand such materials, and the model describes the rich phenomenology. We find that the photoreaction rate depends sensitively on temperature: At temperatures below the crystal-melt transition temperature, photoreaction is collective, requires a critical light intensity, and shows an abrupt first-order phase transition manifesting nucleation and growth; at temperatures above the transition temperature, photoreaction is independent and follows first-order kinetics. Further, the phase transition depends significantly on the exact forms of spontaneous strain during the crystal-melt and trans-cis transitions. A nonmonotonic change of photopersistent cis ratio with increasing temperature is observed accompanied by a reentrant crystallization of trans below the melting temperature. A pseudo phase diagram is subsequently presented with varying temperature and light intensity along with the resulting actuation strain. These insights can assist the further development of these materials.
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Affiliation(s)
- Ruobing Bai
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
| | - Eric Ocegueda
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
| | - Kaushik Bhattacharya
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
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Angela Mihai L, Goriely A. A pseudo-anelastic model for stress softening in liquid crystal elastomers. Proc Math Phys Eng Sci 2020; 476:20200558. [PMID: 33362420 DOI: 10.1098/rspa.2020.0558] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/05/2020] [Indexed: 11/12/2022] Open
Abstract
Liquid crystal elastomers exhibit stress softening with residual strain under cyclic loads. Here, we model this phenomenon by generalizing the classical pseudo-elastic formulation of the Mullins effect in rubber. Specifically, we modify the neoclassical strain-energy density of liquid crystal elastomers, depending on the deformation and the nematic director, by incorporating two continuous variables that account for stress softening and the associated set strain. As the material behaviour is governed by different forms of the strain-energy density on loading and unloading, the model is referred to as pseudo-anelastic. We then analyse qualitatively the mechanical responses of the material under cyclic uniaxial tension, which is easier to reproduce in practice, and further specialize the model in order to calibrate its parameters to recent experimental data at different temperatures. The excellent agreement between the numerical and experimental results confirms the suitability of our approach. Since the pseudo-energy function is controlled by the strain-energy density for the primary deformation, it is valid also for materials under multiaxial loads. Our study is relevant to mechanical damping applications and serves as a motivation for further experimental tests.
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Affiliation(s)
- L Angela Mihai
- School of Mathematics, Cardiff University, Senghennydd Road, Cardiff CF24 4AG, UK
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, UK
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16
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Kuenstler AS, Lahikainen M, Zhou H, Xu W, Priimagi A, Hayward RC. Reconfiguring Gaussian Curvature of Hydrogel Sheets with Photoswitchable Host-Guest Interactions. ACS Macro Lett 2020; 9:1172-1177. [PMID: 32864191 PMCID: PMC7445929 DOI: 10.1021/acsmacrolett.0c00469] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/22/2020] [Indexed: 11/28/2022]
Abstract
Photoinduced shape morphing has implications in fields ranging from soft robotics to biomedical devices. Despite considerable effort in this area, it remains a challenge to design materials that can be both rapidly deployed and reconfigured into multiple different three-dimensional forms, particularly in aqueous environments. In this work, we present a simple method to program and rewrite spatial variations in swelling and, therefore, Gaussian curvature in thin sheets of hydrogels using photoswitchable supramolecular complexation of azobenzene pendent groups with dissolved α-cyclodextrin. We show that the extent of swelling can be programmed via the proportion of azobenzene isomers, with a 60% decrease in areal swelling from the all trans to the predominantly cis state near room temperature. The use of thin gel sheets provides fast response times in the range of a few tens of seconds, while the shape change is persistent in the absence of light thanks to the slow rate of thermal cis-trans isomerization. Finally, we demonstrate that a single gel sheet can be programmed with a first swelling pattern via spatially defined illumination with ultraviolet light, then erased with white light, and finally redeployed with a different swelling pattern.
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Affiliation(s)
- Alexa S. Kuenstler
- Department of Polymer
Science and Engineering, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
| | - Markus Lahikainen
- Smart Photonic Materials, Faculty of Engineering
and Natural Sciences, Tampere University, P.O. Box 541F1-33101, Tampere, Finland
| | - Hantao Zhou
- Department of Polymer
Science and Engineering, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
| | - Wenwen Xu
- Department of Polymer
Science and Engineering, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
| | - Arri Priimagi
- Smart Photonic Materials, Faculty of Engineering
and Natural Sciences, Tampere University, P.O. Box 541F1-33101, Tampere, Finland
| | - Ryan C. Hayward
- Department of Polymer
Science and Engineering, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
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17
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Abstract
AbstractThis article introduces the general characteristics of the diarylethene class of photochromic dye and the structural features that make photochromism possible. It touches on the methodologies employed to synthesize these compounds as well as the influences that typical substitution patterns exert on photocoloration. A demonstration is then given of the great diversity pertaining to the potential applications in which researchers are seeking to exploit them as functional colorants.
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Affiliation(s)
- Andrew Towns
- Technical, Lambson Ltd, Clifford House, York Road, Wetherby, West Yorkshire, LS22 7NSUnited Kingdom of Great Britain and Northern Ireland
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18
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Kuenstler AS, Chen Y, Bui P, Kim H, DeSimone A, Jin L, Hayward RC. Blueprinting Photothermal Shape-Morphing of Liquid Crystal Elastomers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2000609. [PMID: 32173919 DOI: 10.1002/adma.202000609] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/02/2020] [Accepted: 03/03/2020] [Indexed: 06/10/2023]
Abstract
Liquid crystal elastomers (LCEs) are an attractive platform for dynamic shape-morphing due to their ability to rapidly undergo large deformations. While recent work has focused on patterning the director orientation field to achieve desired target shapes, this strategy cannot be generalized to material systems where high-resolution surface alignment is impractical. Instead of programming the local orientation of anisotropic deformation, an alternative strategy for prescribed shape-morphing by programming the magnitude of stretch ratio in a thin LCE sheet with constant director orientation is developed here. By spatially patterning the concentration of gold nanoparticles, uniform illumination leads to gradients in photothermal heat generation and therefore spatially nonuniform deformation profiles that drive out-of-plane buckling of planar films into predictable 3D shapes. Experimentally realized shapes are shown to agree closely with both finite element simulations and geometric predictions for systems with unidirectional variation in deformation magnitude. Finally, the possibility to achieve complex oscillatory motion driven by uniform illumination of a free-standing patterned sheet is demonstrated.
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Affiliation(s)
- Alexa S Kuenstler
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA
| | - Yuzhen Chen
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Phuong Bui
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA
| | - Hyunki Kim
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA
| | - Antonio DeSimone
- MathLab, SISSA-International School for Advanced Studies, Trieste, 34136, Italy
- Department of Excellence in Robotics and AI, Scuola Superiore Sant'Anna, Pisa, 56127, Italy
| | - Lihua Jin
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Ryan C Hayward
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA
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19
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Editorial overview: Particle system shape change and response. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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