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Pinchin NP, Guo H, Meteling H, Deng Z, Priimagi A, Shahsavan H. Liquid Crystal Networks Meet Water: It's Complicated! ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2303740. [PMID: 37392137 DOI: 10.1002/adma.202303740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/21/2023] [Accepted: 06/29/2023] [Indexed: 07/03/2023]
Abstract
Soft robots are composed of compliant materials that facilitate high degrees of freedom, shape-change adaptability, and safer interaction with humans. An attractive choice of material for soft robotics is crosslinked networks of liquid crystal polymers (LCNs), as they are responsive to a wide variety of external stimuli and capable of undergoing fast, programmable, complex shape morphing, which allows for their use in a wide range of soft robotic applications. However, unlike hydrogels, another popular material in soft robotics, LCNs have limited applicability in flooded or aquatic environments. This can be attributed not only to the poor efficiency of common LCN actuation methods underwater but also to the complicated relationship between LCNs and water. In this review, the relationship between water and LCNs is elaborated and the existing body of literature is surveyed where LCNs, both hygroscopic and non-hygroscopic, are utilized in aquatic soft robotic applications. Then the challenges LCNs face in widespread adaptation to aquatic soft robotic applications are discussed and, finally, possible paths forward for their successful use in aquatic environments are envisaged.
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Affiliation(s)
- Natalie P Pinchin
- Department of Chemical Engineering, Waterloo Institute for Nanotechnology, Centre for Bioengineering and Biotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Hongshuang Guo
- Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere, FI-33101, Finland
| | - Henning Meteling
- Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere, FI-33101, Finland
| | - Zixuan Deng
- Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere, FI-33101, Finland
| | - Arri Priimagi
- Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere, FI-33101, Finland
| | - Hamed Shahsavan
- Department of Chemical Engineering, Waterloo Institute for Nanotechnology, Centre for Bioengineering and Biotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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2
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Liu G, Deng Y, Ni B, Nguyen GTM, Vancaeyzeele C, Brûlet A, Vidal F, Plesse C, Li MH. Electroactive Bi-Functional Liquid Crystal Elastomer Actuators. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2307565. [PMID: 37946670 DOI: 10.1002/smll.202307565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/17/2023] [Indexed: 11/12/2023]
Abstract
Liquid crystal elastomers (LCEs) with promising applications in the field of actuators and soft robotics are reported. However, most of them are activated by external heating or light illumination. The examples of electroactive LCEs are still limited; moreover, they are monofunctional with one type of deformation (bending or contraction). Here, the study reports on trilayer electroactive LCE (eLCE) by intimate combination of LCE and ionic electroactive polymer device (i-EAD). This eLCE is bi-functional and can perform either bending or contractile deformations by the control of the low-voltage stimulation. By applying a voltage of ±2 V at 0.1 Hz, the redox behavior and associated ionic motion provide a bending strain difference of 0.80%. Besides, by applying a voltage of ±6 V at 10 Hz, the ionic current-induced Joule heating triggers the muscle-like linear contraction with 20% strain for eLCE without load. With load, eLCE can lift a weight of 270 times of eLCE-actuator weight, while keeping 20% strain and affording 5.38 kJ·m-3 work capacity. This approach of combining two smart polymer technologies (LCE and i-EAD) in a single device is promising for the development of smart materials with multiple degrees of freedom in soft robotics, electronic devices, and sensors.
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Affiliation(s)
- Gaoyu Liu
- Chimie ParisTech, Université Paris Sciences & Lettres, CNRS, Institut de Recherche de Chimie Paris, UMR8247, 11 rue Pierre et Marie Curie, Paris, 75005, France
| | - Yakui Deng
- Chimie ParisTech, Université Paris Sciences & Lettres, CNRS, Institut de Recherche de Chimie Paris, UMR8247, 11 rue Pierre et Marie Curie, Paris, 75005, France
| | - Bin Ni
- Chimie ParisTech, Université Paris Sciences & Lettres, CNRS, Institut de Recherche de Chimie Paris, UMR8247, 11 rue Pierre et Marie Curie, Paris, 75005, France
| | - Giao T M Nguyen
- CY Cergy Paris Université, Laboratoire de physicochimie des polymères et des interfaces (LPPI), 5 mail Gay Lussac, Cergy-Pontoise, Cedex, 95031, France
| | - Cédric Vancaeyzeele
- CY Cergy Paris Université, Laboratoire de physicochimie des polymères et des interfaces (LPPI), 5 mail Gay Lussac, Cergy-Pontoise, Cedex, 95031, France
| | - Annie Brûlet
- Laboratoire Léon Brillouin, Université Paris-Saclay, UMR12 CEA-CNRS, CEA Saclay, 3 rue Joliot Curie, Gif sur Yvette, Cedex, 91191, France
| | - Frédéric Vidal
- CY Cergy Paris Université, Laboratoire de physicochimie des polymères et des interfaces (LPPI), 5 mail Gay Lussac, Cergy-Pontoise, Cedex, 95031, France
| | - Cédric Plesse
- CY Cergy Paris Université, Laboratoire de physicochimie des polymères et des interfaces (LPPI), 5 mail Gay Lussac, Cergy-Pontoise, Cedex, 95031, France
| | - Min-Hui Li
- Chimie ParisTech, Université Paris Sciences & Lettres, CNRS, Institut de Recherche de Chimie Paris, UMR8247, 11 rue Pierre et Marie Curie, Paris, 75005, France
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Zhou J, Zhao S, Tang L, Zhang D, Sheng B. Programmable and Weldable Superelastic EGaIn/TPU Composite Fiber by Wet Spinning for Flexible Electronics. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 38031357 DOI: 10.1021/acsami.3c11068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
As an essential component of flexible electronics, superelastic conductive fibers with good mechanical and electrical properties have drawn significant attention, especially in their preparation. In this study, we prepared a superelastic conductive fiber composed of eutectic gallium-indium (EGaIn) and thermoplastic polyurethane (TPU) by simple wet spinning. The composite conductive fiber with a liquid metal (LM) content of 85 wt % achieved a maximum strain at a break of 659.2%, and after the conductive pathway in the porous structure of the composite fibers was fully activated, high conductivity (1.2 × 105 S/m) was achieved with 95 wt % LM by mechanical sintering and training processes. The prepared conductive fibers exhibited a stable resistive response as the fibers were strained and could be sewn into fabrics and used as wearable strain sensors to monitor various human motions. These conductive fibers can be molded into helical by heating, and they have excellent electrical properties at a maximum mechanical strain of 3400% (resistance change <0.27%) with a helical index of 11. Moreover, the conductive fibers can be welded to various two or three-dimensional conductors. In summary, with a scalable manufacturing process, weldability, superelasticity, and high electrical conductivity, EGaIn/TPU composite fibers fabricated by wet spinning have considerable potential for flexible electronics.
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Affiliation(s)
- Jingyu Zhou
- School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
- Shanghai Key Laboratory of Modern Optical Systems, Engineering Research Center of Optical Instruments and Systems, Shanghai 200093, China
| | - Shanshan Zhao
- School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
- Shanghai Key Laboratory of Modern Optical Systems, Engineering Research Center of Optical Instruments and Systems, Shanghai 200093, China
| | - Lei Tang
- School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
- Shanghai Key Laboratory of Modern Optical Systems, Engineering Research Center of Optical Instruments and Systems, Shanghai 200093, China
| | - Dawei Zhang
- School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
- Shanghai Key Laboratory of Modern Optical Systems, Engineering Research Center of Optical Instruments and Systems, Shanghai 200093, China
| | - Bin Sheng
- School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
- Shanghai Key Laboratory of Modern Optical Systems, Engineering Research Center of Optical Instruments and Systems, Shanghai 200093, China
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Vinciguerra MR, Patel DK, Zu W, Tavakoli M, Majidi C, Yao L. Multimaterial Printing of Liquid Crystal Elastomers with Integrated Stretchable Electronics. ACS APPLIED MATERIALS & INTERFACES 2023; 15:24777-24787. [PMID: 37163362 DOI: 10.1021/acsami.2c23028] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Liquid crystal elastomers (LCEs) have grown in popularity in recent years as a stimuli-responsive material for soft actuators and shape reconfigurable structures. To make these material systems electrically responsive, they must be integrated with soft conductive materials that match the compliance and deformability of the LCE. This study introduces a design and manufacturing methodology for combining direct ink write (DIW) 3D printing of soft, stretchable conductive inks with DIW-based "4D printing" of LCE to create fully integrated, electrically responsive, shape programmable matter. The conductive ink is composed of a soft thermoplastic elastomer, a liquid metal alloy (eutectic gallium indium, EGaIn), and silver flakes, exhibiting both high stretchability and conductivity (order of 105 S m-1). Empirical tuning of the LCE printing parameters gives rise to a smooth surface (<10 μm) for patterning the conductive ink with controlled trace dimensions. This multimaterial printing method is used to create shape reconfigurable LCE devices with on-demand circuit patterning that could otherwise not be easily fabricated through traditional means, such as an LCE bending actuator able to blink a Morse code signal and an LCE crawler with an on/off photoresistor controller. In contrast to existing fabrication methodologies, the inclusion of the conductive ink allows for stable power delivery to surface mount devices and Joule heating traces in a highly dynamic LCE system. This digital fabrication approach can be leveraged to push LCE actuators closer to becoming functional devices, such as shape programmable antennas and actuators with integrated sensing.
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Affiliation(s)
- Michael R Vinciguerra
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, United States
| | - Dinesh K Patel
- Human Computer Interaction Institute, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, United States
| | - Wuzhou Zu
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, United States
| | - Mahmoud Tavakoli
- Institute of Systems and Robotics, Department of Electrical Engineering, University of Coimbra, Coimbra 3090-290, Portugal
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, United States
| | - Lining Yao
- Human Computer Interaction Institute, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, United States
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Zhao L, Tian H, Liu H, Zhang W, Zhao F, Song X, Shao J. Bio-Inspired Soft-Rigid Hybrid Smart Artificial Muscle Based on Liquid Crystal Elastomer and Helical Metal Wire. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206342. [PMID: 36653937 DOI: 10.1002/smll.202206342] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 01/01/2023] [Indexed: 06/17/2023]
Abstract
Artificial muscles are of significant value in robotic applications. Rigid artificial muscles possess a strong load-bearing capacity, while their deformation is small; soft artificial muscles can be shifted to a large degree; however, their load-bearing capacity is weak. Furthermore, artificial muscles are generally controlled in an open loop due to a lack of deformation-related feedback. Human arms include muscles, bones, and nerves, which ingeniously coordinate the actuation, load-bearing, and sensory systems. Inspired by this, a soft-rigid hybrid smart artificial muscle (SRH-SAM) based on liquid crystal elastomer (LCE) and helical metal wire is proposed. The thermotropic responsiveness of the LCE is adopted for large reversible deformation, and the helical metal wire is used to fulfill high bearing capacity and electric heating function requirements. During actuation, the helical metal wire's resistance changes with the LCE's electrothermal deformation, thereby achieving deformation-sensing characteristics. Based on the proposed SRH-SAM, a reconfigurable blazed grating plane and the effective switch between attachment and detachment in bionic dry adhesion are accomplished. The SRH-SAM opens a new avenue for designing smart artificial muscles and can promote the development of artificial muscle-based devices.
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Affiliation(s)
- Limeng Zhao
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Hongmiao Tian
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Haoran Liu
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Weitian Zhang
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Fabo Zhao
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Xiaowen Song
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Jinyou Shao
- Micro-/Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
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Akyildiz K, Kim JH, So JH, Koo HJ. Recent progress on micro- and nanoparticles of gallium-based liquid metal: From preparation to applications. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.09.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Long F, Xu G, Wang J, Ren Y, Cheng Y. Variable Stiffness Conductive Composites by 4D Printing Dual Materials Alternately. MICROMACHINES 2022; 13:1343. [PMID: 36014265 PMCID: PMC9415883 DOI: 10.3390/mi13081343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/09/2022] [Accepted: 08/11/2022] [Indexed: 06/15/2023]
Abstract
Materials that can be designed with programmable properties and which change in response to external stimuli are of great importance in numerous fields of soft actuators, involving robotics, drug delivery and aerospace applications. In order to improve the interaction of human and robots, materials with variable stiffness are introduced to develop their compliance. A variable stiffness composite has been investigated in this paper, which is composed of liquid metals (LMs) and silicone elastomers. The phase changing materials (LMs) have been encapsulated into silicone elastomer by printing the dual materials alternately with three-dimensional direct ink writing. Such composites enable the control over their own stiffness between soft and rigid states through LM effective phase transition. The tested splines demonstrated that the stiffness changes approximately exceeded 1900%, and the storage modulus is 4.75 MPa and 0.2 MPa when LM is rigid and soft, respectively. In the process of heating up, the stretching strain can be enlarged by at least three times, but the load capacity is weakened. At a high temperature, the resistance of the conductive composites changes with the deformation degree, which is expected to be applied in the field of soft sensing actuators.
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Affiliation(s)
- Fei Long
- Zhejiang Key Laboratory of Additive Manufacturing Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
- Research Group for Fluids and Thermal Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
| | - Gaojie Xu
- Zhejiang Key Laboratory of Additive Manufacturing Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Jing Wang
- Department of Electrical and Electronic Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
| | - Yong Ren
- Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
- Research Group for Fluids and Thermal Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
- Key Laboratory of Carbonaceous Wastes Processing and Process Intensification Research of Zhejiang Province, University of Nottingham Ningbo China, Ningbo 315100, China
| | - Yuchuan Cheng
- Zhejiang Key Laboratory of Additive Manufacturing Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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Xiao YY, Jiang ZC, Hou JB, Chen XS, Zhao Y. Electrically driven liquid crystal network actuators. SOFT MATTER 2022; 18:4850-4867. [PMID: 35730498 DOI: 10.1039/d2sm00544a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Soft actuators based on liquid crystal networks (LCNs) have aroused great scientific interest for use as stimuli-controlled shape-changing and moving components for robotic devices due to their fast, large, programmable and solvent-free actuation responses. Recently, various LCN actuators have been implemented in soft robotics using stimulus sources such as heat, light, humidity and chemical reactions. Among them, electrically driven LCN actuators allow easy modulation and programming of the input electrical signals (amplitude, phase, and frequency) as well as stimulation throughout the volume, rendering them promising actuators for practical applications. Herein, the progress of electrically driven LCN actuators regarding their construction, actuation mechanisms, actuation performance, actuation programmability and the design strategies for intelligent systems is elucidated. We also discuss new robotic functions and advanced actuation control. Finally, an outlook is provided, highlighting the research challenges faced with this type of actuator.
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Affiliation(s)
- Yao-Yu Xiao
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
| | - Zhi-Chao Jiang
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
| | - Jun-Bo Hou
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
| | - Xin-Shi Chen
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
| | - Yue Zhao
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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Zadan M, Patel DK, Sabelhaus AP, Liao J, Wertz A, Yao L, Majidi C. Liquid Crystal Elastomer with Integrated Soft Thermoelectrics for Shape Memory Actuation and Energy Harvesting. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200857. [PMID: 35384096 DOI: 10.1002/adma.202200857] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/19/2022] [Indexed: 06/14/2023]
Abstract
Liquid crystal elastomers (LCEs) have attracted tremendous interest as actuators for soft robotics due to their mechanical and shape memory properties. However, LCE actuators typically respond to thermal stimulation through active Joule heating and passive cooling, which make them difficult to control. In this work, LCEs are combined with soft, stretchable thermoelectrics to create transducers capable of electrically controlled actuation, active cooling, and thermal-to-electrical energy conversion. The thermoelectric layers are composed of semiconductors embedded within a 3D printed elastomer matrix and wired together with eutectic gallium-indium (EGaIn) liquid metal interconnects. This layer is covered on both sides with LCE, which alternately heats and cools to achieve cyclical bending actuation in response to voltage-controlled Peltier activation. Moreover, the thermoelectric layer can harvest energy from thermal gradients between the two LCE layers through the Seebeck effect, allowing for regenerative energy harvesting. As demonstrations, first, closed-loop control of the transducer is performed to rapidly track a changing actuator position. Second, a soft robotic walker that is capable of walking toward a heat source and harvesting energy is introduced. Lastly, phototropic-inspired autonomous deflection of the limbs toward a heat source is shown, demonstrating an additional method to increase energy recuperation efficiency for soft systems.
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Affiliation(s)
- Mason Zadan
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Dinesh K Patel
- Human-Computer Interaction Institute, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Andrew P Sabelhaus
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Jiahe Liao
- The Robotics Institute, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Anthony Wertz
- The Robotics Institute, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Lining Yao
- Human-Computer Interaction Institute, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
- The Robotics Institute, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
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Del Pozo M, Sol JAHP, Schenning APHJ, Debije MG. 4D Printing of Liquid Crystals: What's Right for Me? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2104390. [PMID: 34716625 DOI: 10.1002/adma.202104390] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/20/2021] [Indexed: 05/24/2023]
Abstract
Recent years have seen major advances in the developments of both additive manufacturing concepts and responsive materials. When combined as 4D printing, the process can lead to functional materials and devices for use in health, energy generation, sensing, and soft robots. Among responsive materials, liquid crystals, which can deliver programmed, reversible, rapid responses in both air and underwater, are a prime contender for additive manufacturing, given their ease of use and adaptability to many different applications. In this paper, selected works are compared and analyzed to come to a didactical overview of the liquid crystal-additive manufacturing junction. Reading from front to back gives the reader a comprehensive understanding of the options and challenges in the field, while researchers already experienced in either liquid crystals or additive manufacturing are encouraged to scan through the text to see how they can incorporate additive manufacturing or liquid crystals into their own work. The educational text is closed with proposals for future research in this crossover field.
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Affiliation(s)
- Marc Del Pozo
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
| | - Jeroen A H P Sol
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
| | - Albert P H J Schenning
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
| | - Michael G Debije
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
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Abstract
Smart soft materials are envisioned to be the building blocks of the next generation of advanced devices and digitally augmented technologies. In this context, liquid crystals (LCs) owing to their responsive and adaptive attributes could serve as promising smart soft materials. LCs played a critical role in revolutionizing the information display industry in the 20th century. However, in the turn of the 21st century, numerous beyond-display applications of LCs have been demonstrated, which elegantly exploit their controllable stimuli-responsive and adaptive characteristics. For these applications, new LC materials have been rationally designed and developed. In this Review, we present the recent developments in light driven chiral LCs, i.e., cholesteric and blue phases, LC based smart windows that control the entrance of heat and light from outdoor to the interior of buildings and built environments depending on the weather conditions, LC elastomers for bioinspired, biological, and actuator applications, LC based biosensors for detection of proteins, nucleic acids, and viruses, LC based porous membranes for the separation of ions, molecules, and microbes, living LCs, and LCs under macro- and nanoscopic confinement. The Review concludes with a summary and perspectives on the challenges and opportunities for LCs as smart soft materials. This Review is anticipated to stimulate eclectic ideas toward the implementation of the nature's delicate phase of matter in future generations of smart and augmented devices and beyond.
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Affiliation(s)
- Hari Krishna Bisoyi
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States
| | - Quan Li
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States.,Institute of Advanced Materials, School of Chemistry and Chemical Engineering, and Jiangsu Hi-Tech Key Laboratory for Biomedical Research, Southeast University, Nanjing 211189, China
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Light-Driven Linear Inchworm Motor Based on Liquid Crystal Elastomer Actuators Fabricated with Rubbing Overwriting. MATERIALS 2021; 14:ma14216688. [PMID: 34772214 PMCID: PMC8587320 DOI: 10.3390/ma14216688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/27/2021] [Accepted: 11/03/2021] [Indexed: 11/23/2022]
Abstract
Linear displacement is used for positioning and scanning, e.g., in robotics at different scales or in scientific instrumentation. Most linear motors are either powered by rotary drives or are driven directly by pressure, electromagnetic forces or a shape change in a medium, such as piezoelectrics or shape-memory materials. Here, we present a centimeter-scale light-powered linear inchworm motor, driven by two liquid crystal elastomer (LCE) accordion-like actuators. The rubbing overwriting technique was used to fabricate the LCE actuators, made of elastomer film with patterned alignment. In the linear motor, a scanned green laser beam induces a sequence of travelling deformations in a pair of actuators that move a gripper, which couples to a shaft via friction moving it with an average speed in the order of millimeters per second. The prototype linear motor demonstrates how LCE light-driven actuators with a limited stroke can be used to drive more complex mechanisms, where large displacements can be achieved, defined only by the technical constrains (the shaft length in our case), and not by the limited strain of the material. Inchworm motors driven by LCE actuators may be scaled down to sub-millimeter size and can be used in applications where remote control and power supply with light, either delivered in free space beams or via fibers, is an advantage.
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Levine DJ, Turner KT, Pikul JH. Materials with Electroprogrammable Stiffness. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2007952. [PMID: 34245062 DOI: 10.1002/adma.202007952] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/19/2021] [Indexed: 05/18/2023]
Abstract
Stiffness is a mechanical property of vital importance to any material system and is typically considered a static quantity. Recent work, however, has shown that novel materials with programmable stiffness can enhance the performance and simplify the design of engineered systems, such as morphing wings, robotic grippers, and wearable exoskeletons. For many of these applications, the ability to program stiffness with electrical activation is advantageous because of the natural compatibility with electrical sensing, control, and power networks ubiquitous in autonomous machines and robots. The numerous applications for materials with electrically driven stiffness modulation has driven a rapid increase in the number of publications in this field. Here, a comprehensive review of the available materials that realize electroprogrammable stiffness is provided, showing that all current approaches can be categorized as using electrostatics or electrically activated phase changes, and summarizing the advantages, limitations, and applications of these materials. Finally, a perspective identifies state-of-the-art trends and an outlook of future opportunities for the development and use of materials with electroprogrammable stiffness.
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Affiliation(s)
- David J Levine
- Department of Mechanical Engineering & Applied Mechanics, 220 S. 33rd St., Philadelphia, PA, 19104, USA
| | - Kevin T Turner
- Department of Mechanical Engineering & Applied Mechanics, 220 S. 33rd St., Philadelphia, PA, 19104, USA
| | - James H Pikul
- Department of Mechanical Engineering & Applied Mechanics, 220 S. 33rd St., Philadelphia, PA, 19104, USA
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Gupta D, Kula P, Bhattacharjee A. Investigation of a partially fluorinated chiral antiferroelectric liquid crystalline material with large negative dielectric anisotropy. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Ilami M, Bagheri H, Ahmed R, Skowronek EO, Marvi H. Materials, Actuators, and Sensors for Soft Bioinspired Robots. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2003139. [PMID: 33346386 DOI: 10.1002/adma.202003139] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/15/2020] [Indexed: 05/23/2023]
Abstract
Biological systems can perform complex tasks with high compliance levels. This makes them a great source of inspiration for soft robotics. Indeed, the union of these fields has brought about bioinspired soft robotics, with hundreds of publications on novel research each year. This review aims to survey fundamental advances in bioinspired soft actuators and sensors with a focus on the progress between 2017 and 2020, providing a primer for the materials used in their design.
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Affiliation(s)
- Mahdi Ilami
- School for Engineering of Matter, Transport & Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Hosain Bagheri
- School for Engineering of Matter, Transport & Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Reza Ahmed
- School for Engineering of Matter, Transport & Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - E Olga Skowronek
- School for Engineering of Matter, Transport & Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Hamid Marvi
- School for Engineering of Matter, Transport & Energy, Arizona State University, Tempe, AZ, 85287, USA
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16
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Ambulo CP, Ford MJ, Searles K, Majidi C, Ware TH. 4D-Printable Liquid Metal-Liquid Crystal Elastomer Composites. ACS APPLIED MATERIALS & INTERFACES 2021; 13:12805-12813. [PMID: 33356119 DOI: 10.1021/acsami.0c19051] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Soft actuators that undergo programmable shape change in response to a stimulus are enabling components of future soft robots and other soft machines. Strategies to power these actuators often require the incorporation of rigid, electrically conductive materials into the soft actuator, thus limiting the compliance and shape change of the material. In this study, we develop a 4D-printable composite composed of liquid crystal elastomer (LCE) matrix with dispersed droplets of eutectic gallium indium alloy (EGaIn). Using deformable EGaIn droplets in place of rigid conductive fillers preserves the compliance and shape-morphing properties of the LCE. The process enables 4D-printed LCE actuators capable of photothermal and electrothermal actuation. At low liquid metal (LM) concentrations (71 wt %), the composite actuator exhibits a photothermal response upon irradiation of near-IR light. Printed actuators with a twisted nematic configuration are capable of bending angles of 150° at 800 mW cm-2. At higher LM concentrations (88 wt %), the embedded LM droplets can form percolating networks that conduct electricity and enable electrical Joule heating of the LCE. Actuation strain ranging from 5 to 12% is controlled by the amount of electrical power that is delivered to the composite. We also introduce a method for multimaterial printing of monolithic structures where the LM filler loading is spatially varied. These multifunctional materials exhibit innate responsivity where the actuator behaves as an electrical switch and can report one of two states (on/off). These multiresponsive, 4D-printable composites enable multifunctional, mechanically active structures that can be powered with IR light or low DC voltages.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Michael J Ford
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kyle Searles
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
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Martinez A, Clement A, Gao J, Kocherzat J, Tabrizi M, Shankar MR. Thermomechanically active electrodes power work-dense soft actuators. SOFT MATTER 2021; 17:1521-1529. [PMID: 33331368 DOI: 10.1039/d0sm01399d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The effect of chain extender structure and composition on the thermomechanical properties of liquid crystal elastomers (LCE) synthesized using thiol-acrylate Michael addition is presented. The intrinsic molecular stiffness of the thiol chain extender and its relative molar ratio to acrylate-based host mesogens determine the magnitudes of the thermomechanical strains, temperatures at which they are realized and the mechanical work-content. A non-linear structure-property relationship emerges, wherein higher concentrations of flexible extenders first magnify the thermomechanical sensitivity, but a continued increase leads to weaker actuation. Understanding this interplay leads to a composite material platform, enabling a peak specific work production of ∼2 J kg-1 using ∼115 mW of electrical power supplied at 2 V. Composites of LCE with eGaIn liquid metal (LM) are prepared, which act as heaters, while being capable of actuation themselves. The thermomechanically active electrodes convert the electrical power into Joule heat, which they efficiently couple with the neat LCE to which they are bound. This system harnesses the nascent responsiveness of the LCE using electrodes that work with them, instead of fighting against them (or passively standing in the way). Specific work generated increases when subjected to increasing levels of load, reaching a peak at loads ∼260× the actuator weight. These ideas are extended to tri-layered actuators, where LCE films with orthogonal molecular orientations sandwich LCE-LM composite heaters. Torsional actuation modes are harnessed to twist under load.
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Affiliation(s)
- Angel Martinez
- 1025 Benedum Hall, Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Arul Clement
- 1025 Benedum Hall, Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Junfeng Gao
- 1025 Benedum Hall, Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Julia Kocherzat
- 1025 Benedum Hall, Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Mohsen Tabrizi
- 1025 Benedum Hall, Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - M Ravi Shankar
- 1025 Benedum Hall, Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
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Mou L, Qi J, Tang L, Dong R, Xia Y, Gao Y, Jiang X. Highly Stretchable and Biocompatible Liquid Metal-Elastomer Conductors for Self-Healing Electronics. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2005336. [PMID: 33236828 DOI: 10.1002/smll.202005336] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 11/05/2020] [Indexed: 06/11/2023]
Abstract
Highly stretchable, conductive, biocompatible conductors, and connectors are crucial for the fabrication of flexible devices. However, it remains a problem to get highly stretchable, conductive materials with low cost on a large scale. Another problem in production is the connection between soft and rigid components. Here, a new conductive nanocomposite is reported by mixing the 11-mercaptoundecanoic acid (MUA) modified liquid metal (LM) nanoparticles with polystyrene-block-polybutadiene-block-polystyrene (SBS), which is biocompatible (in vivo and in vitro), conductive (12 000 S cm-1 of conductivity), and stretchable (800% of elongation). Apart from its good performance, this material can be produced on a large scale by using a commercial polymer product and a straightforward physical production process. MUA is used to compromise the dense "gallium oxide shell" of liquid metal nanoparticles such that the whole composite can become conductive. By using resin to modify this composite, this new conductive material can be adhesive and highly conductive, and serve as a stable and efficient connector between soft conductor and rigid component.
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Affiliation(s)
- Lei Mou
- National Center for NanoScience and Technology, University of Chinese Academy of Sciences, No. 11 Zhongguancun Beiyitiao, Beijing, 100190, P. R. China
- Department of Biomedical Engineering, Southern University of Science and Technology, No 1088, Xueyuan Rd., Xili, Nanshan District, Shenzhen, Guangdong, 518055, P. R. China
- Department of Clinical Laboratory, Third Affiliated Hospital of Guangzhou Medical University, No. 63 Duobao Road, Liwan District, Guangzhou, Guangdong, 510150, P. R. China
| | - Jie Qi
- National Center for NanoScience and Technology, University of Chinese Academy of Sciences, No. 11 Zhongguancun Beiyitiao, Beijing, 100190, P. R. China
- Department of Biomedical Engineering, Southern University of Science and Technology, No 1088, Xueyuan Rd., Xili, Nanshan District, Shenzhen, Guangdong, 518055, P. R. China
| | - Lixue Tang
- Department of Biomedical Engineering, Southern University of Science and Technology, No 1088, Xueyuan Rd., Xili, Nanshan District, Shenzhen, Guangdong, 518055, P. R. China
| | - Ruihua Dong
- Department of Biomedical Engineering, Southern University of Science and Technology, No 1088, Xueyuan Rd., Xili, Nanshan District, Shenzhen, Guangdong, 518055, P. R. China
| | - Yong Xia
- Department of Clinical Laboratory, Third Affiliated Hospital of Guangzhou Medical University, No. 63 Duobao Road, Liwan District, Guangzhou, Guangdong, 510150, P. R. China
| | - Yuan Gao
- National Center for NanoScience and Technology, University of Chinese Academy of Sciences, No. 11 Zhongguancun Beiyitiao, Beijing, 100190, P. R. China
| | - Xingyu Jiang
- National Center for NanoScience and Technology, University of Chinese Academy of Sciences, No. 11 Zhongguancun Beiyitiao, Beijing, 100190, P. R. China
- Department of Biomedical Engineering, Southern University of Science and Technology, No 1088, Xueyuan Rd., Xili, Nanshan District, Shenzhen, Guangdong, 518055, P. R. China
- Department of Clinical Laboratory, Third Affiliated Hospital of Guangzhou Medical University, No. 63 Duobao Road, Liwan District, Guangzhou, Guangdong, 510150, P. R. China
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