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Haputhanthrige NP, Paladugu S, Lavrentovich MO, Lavrentovich OD. Trapping of isotropic droplets by disclinations in nematic liquid crystals controlled by surface anchoring and elastic constant disparity. Phys Rev E 2024; 109:064703. [PMID: 39020964 DOI: 10.1103/physreve.109.064703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 05/24/2024] [Indexed: 07/20/2024]
Abstract
Linear defects such as dislocations and disclinations in ordered materials attract foreign particles since they replace strong elastic distortions at the defect cores. In this work, we explore the behavior of isotropic droplets nucleating at singular disclinations in a nematic liquid crystal, predesigned by surface photopatterning. Experiments show that in the biphasic nematic-isotropic region, although the droplets are attracted to the disclination cores, their centers of mass shift away from the core centers as the temperature increases. The shift is not random, being deterministically defined by the surrounding director field. The effect is explained by the balance of interfacial anchoring and bulk elasticity. An agreement with the experiment can be achieved only if the model accounts for the disparity of the nematic elastic constants; the so-called one-constant approximation, often used in the theoretical analysis of liquid crystals, produces qualitatively wrong predictions. In particular, the experimentally observed shift towards the bend region around a +1/2 disclination core can be explained only when the bend constant is larger than the splay constant. The described dependence of the precise location of a foreign inclusion at defect cores on the elastic and surface anchoring properties can be used in rational design of microscale architectures.
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Affiliation(s)
| | | | - Maxim O Lavrentovich
- Department of Earth, Environment, and Physics, Worcester State University, Worcester, Massachusetts 01602, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA
- Department of Physics, Kent State University, Kent, Ohio 44242, USA
- Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, USA
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2
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Feng W, He Q, Zhang L. Embedded Physical Intelligence in Liquid Crystalline Polymer Actuators and Robots. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2312313. [PMID: 38375751 DOI: 10.1002/adma.202312313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/27/2024] [Indexed: 02/21/2024]
Abstract
Responsive materials possess the inherent capacity to autonomously sense and respond to various external stimuli, demonstrating physical intelligence. Among the diverse array of responsive materials, liquid crystalline polymers (LCPs) stand out for their remarkable reversible stimuli-responsive shape-morphing properties and their potential for creating soft robots. While numerous reviews have extensively detailed the progress in developing LCP-based actuators and robots, there exists a need for comprehensive summaries that elucidate the underlying principles governing actuation and how physical intelligence is embedded within these systems. This review provides a comprehensive overview of recent advancements in developing actuators and robots endowed with physical intelligence using LCPs. This review is structured around the stimulus conditions and categorizes the studies involving responsive LCPs based on the fundamental control and stimulation logic and approach. Specifically, three main categories are examined: systems that respond to changing stimuli, those operating under constant stimuli, and those equip with learning and logic control capabilities. Furthermore, the persisting challenges that need to be addressed are outlined and discuss the future avenues of research in this dynamic field.
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Affiliation(s)
- Wei Feng
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Qiguang He
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Zhang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China
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3
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Modin A, Leheny RL, Serra F. Spatial Photo-Patterning of Nematic Liquid Crystal Pretilt and its Application in Fabricating Flat Gradient-Index Lenses. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2310083. [PMID: 38301718 DOI: 10.1002/adma.202310083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 12/14/2023] [Indexed: 02/03/2024]
Abstract
Liquid crystals offer a dynamic platform for developing advanced photonics and soft actuation systems due to their unique and facile tunability and reconfigurability. Achieving precise spatial patterning of the liquid crystal alignment is critical to developing electro-optical devices, programmable origami, directed colloidal assembly, and controlling active matter. Here, a simple method is demonstrated to achieve continuous 3D control of the directions of liquid crystal mesogens using a two-step photo-exposure process. In the first step, polarized light sets the orientation in the plane of confining substrates; the second step uses unpolarized light of a prescribed dose to set the out-of-plane orientation. The method enables smoothly varying orientational patterns with sub-micrometer precision. As a demonstration, the setup is used to create gradient-index lenses with parabolic refractive index profiles that remain stable without external electric fields. The lenses' focal length and sensitivity to light polarization are characterized through experimental and numerical methods. The findings pave the way for developing next-generation photonic devices and actuated materials, with potential applications in molecular self-assembly, re-configurable optics, and responsive matter.
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Affiliation(s)
- Alvin Modin
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Robert L Leheny
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Francesca Serra
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense, DK-5230, Denmark
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4
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Chen H, Jiang M, Guo Y, Chaganava I, Wei QH. Nematic-isotropic phase transitions in thin slabs of liquid crystals with topological defect arrays. SOFT MATTER 2023; 19:8863-8870. [PMID: 37955055 DOI: 10.1039/d3sm01156a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
We study the nematic-to-isotropic phase transitions in thin slabs of nematic liquid crystals with photopatterned director fields of topological defect arrays at constant heating rates and show that the transition kinetics is significantly impacted by both the heating rate and the topological strengths of these defects. Specifically, with ±1/2 defect arrays, the isotropic domains emerge from the defect cores when the heating rate is high, while from random places when the heating rate is low. With ±1 defect arrays, the isotropic domains always emerge from the defect cores regardless of the heating rate. Furthermore, the isotropic domains show significant movements at slow heating rates, and the total area of the isotropic domains grows with the temperature T following a simple power law (T - T')γ, where the exponent γ is approximately 1 in most cases and is 2/3 for the ±1 defect arrays at low heating rates when the isotropic domains are pinned on the defect cores. We attribute this phenomenon to an interplay between the surface tension and bulk free energy.
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Affiliation(s)
- Hao Chen
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Miao Jiang
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Yubing Guo
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Irakli Chaganava
- Institute of Cybernetics, Georgian Technical University, 5 Sandro Euli Str., 0186 Tbilisi, Georgia
| | - Qi-Huo Wei
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
- Center for Complex Flows and Soft Matter Research, Southern University of Science and Technology, Shenzhen, China
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5
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Meng Z, Huang W, Zhang LX, Zhou X, Zhao K, Pu D, Chen L. Large aperture and defect-free liquid crystal planar optics enabled by high-throughput pulsed polarization patterning. OPTICS EXPRESS 2023; 31:30435-30445. [PMID: 37710584 DOI: 10.1364/oe.498970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 08/23/2023] [Indexed: 09/16/2023]
Abstract
The liquid crystal (LC) geometrical phase optics, which is realized by the high-resolution control of the optical axis orientation in transparent micrometer-thin polymer films, is emerging as a next generation of planar optics. It features pronounced optical properties and stimuli-responsive behaviors, which could introduce appealing and new possibilities for photonic purposes. The development of fabrication techniques producing elements with large aperture sizes and arbitrarily varying molecular orientation is of significance in terms of practical utility. Here, we propose the pulsed polarization patterning technique to create large-aperture and defect-free LC geometrical phase elements. We investigated the capability of the azo photo-alignment material responding to nanosecond laser pulses and the corresponding anchoring behaviors to LCs. The threshold was reduced to one fourth of that under the continuous wave recording. The patterning resolution was found to be enhanced to around 0.71 µm, due to the ultra-fast interaction nature of the photo-alignment material with the polarized light field. We proposed the flying exposure mode to deliver high frequency modulated polarized laser pulses (8 kHz), with the precision stage moving in a uniform velocity for light-field stitching and the servo auto-focusing in the sample normal, enabling the stable and reliable polarization patterning for large aperture sizes. We further report on representative fabrication of LC polarization gratings with an aperture of 4 inch and 99.2% average diffraction efficiency.
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6
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Jagodič U, Vellaichamy M, Škarabot M, Muševič I. Surface alignment of nematic liquid crystals by direct laser writing of photopolymer alignment layers. LIQUID CRYSTALS 2023; 50:1999-2009. [PMID: 38352915 PMCID: PMC10860699 DOI: 10.1080/02678292.2023.2242297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/25/2023] [Indexed: 02/16/2024]
Abstract
We demonstrate the fabrication of good quality surface alignment layers on glass by Direct Laser Writing method using a 2-photon polymerisation technique. We use commercially available photosensitive resins to print alignment layers by scanning the focal point of a femtosecond laser near the resin-glass interface. This results in down to ~ 100 nm thin alignment layers that provide good planar anchoring of 5CB and MLC13300, with the easy axis of alignment along the scanning direction. The azimuthal anchoring strength is ~ 5 × 10-6 J/m2 and is an order of magnitude weaker compared to commercial rubbed polyimide alignment layer. The threshold voltage for Fréedericksz transition in a 90° twisted nematic cell is slightly increased compared to conventional rubbed polyimide for printed alignment layers. The turn-on switching time is longer for printed layers compared to polyimide alignment layers, whereas the turn-off time is shorter for printed alignment layers. The advantage of this new method is in its flexibility, as we demonstrate printing of complex surface alignment patterns with alignment layer thickness below 100 nm.
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Affiliation(s)
- Uroš Jagodič
- Condensed Matter Department, J. Stefan Institute, Ljubljana, Slovenia
| | | | - Miha Škarabot
- Condensed Matter Department, J. Stefan Institute, Ljubljana, Slovenia
| | - Igor Muševič
- Condensed Matter Department, J. Stefan Institute, Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
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7
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Kim K, Lee C, Yoon DK. Patterned Hydrophobic Liquid Crystalline Fibers Fabricated from Defect Arrays of Reactive Mesogens via Electric Field Modulation. ACS APPLIED MATERIALS & INTERFACES 2023; 15:8387-8392. [PMID: 36740776 DOI: 10.1021/acsami.2c20495] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We have fabricated patterned fibers using a small-molecular-weight liquid crystal (LC) and reactive mesogens (RMs) under controlled electric fields in which defect arrays are generated depending on the electrode configuration. For this, the AC electric field with interdigitated electrodes is used to develop versatile defect structures of the LC phase. Hydrophobic LC network (LCN) fibers exhibiting porous morphologies have been made by removing the LC part after the polymerization of RM. The resulting LCN fibers show a surface tension reduction characteristic compared to the neat RM film and a sticky characteristic with the water droplet, suggesting a facile way to fabricate the hydrophobic surface that can be used in microdroplet transport.
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Affiliation(s)
- Kyuhwan Kim
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
| | - Changjae Lee
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
| | - Dong Ki Yoon
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
- Graduate School of Nanoscience and Technology and KAIST Institute for Nanocentury, KAIST, Daejeon34141, Republic of Korea
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8
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Kim WS, Im JH, Kim H, Choi JK, Choi Y, Kim YK. Liquid Crystalline Systems from Nature and Interaction of Living Organisms with Liquid Crystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2204275. [PMID: 35861641 DOI: 10.1002/adma.202204275] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Biomaterials, which are substances interacting with biological systems, have been extensively explored to understand living organisms and obtain scientific inspiration (such as biomimetics). However, many aspects of biomaterials have yet to be fully understood. Because liquid crystalline phases are ubiquitously found in biomaterials (e.g., cholesterol, amphiphile, DNA, cellulose, bacteria), therefore, a wide range of research has made attempts to approach unresolved issues with the concept of liquid crystals (LCs). This review presents these studies that address the interactive correlation between biomaterials and LCs. Specifically, intrinsic LC behavior of various biomaterials such as DNA, cellulose nanocrystals, and bacteriaare first introduced. Second, the dynamics of bacteria in LC media are addressed, with focus on how bacteria interact with LCs, and how dynamics of bacteria can be controlled by exploiting the characteristics of LCs. Lastly, how the strong correlation between LCs and biomaterials has been leveraged to design a new class of biosensors with additional functionalities (e.g., self-regulated drug release) that are not available in previous systems is reviewed. Examples addressed in this review convey the message that the intersection between biomaterials and LCs offers deep insights into fundamental understanding of biomaterials, and provides resources for development of transformative technologies.
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Affiliation(s)
- Won-Sik Kim
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jun-Hyung Im
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Hyein Kim
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jin-Kang Choi
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Yena Choi
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Young-Ki Kim
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
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9
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Rajabi M, Lavrentovich O, Shribak M. Instantaneous mapping of liquid crystal orientation using a polychromatic polarizing microscope. LIQUID CRYSTALS 2022; 50:181-190. [PMID: 37293249 PMCID: PMC10249429 DOI: 10.1080/02678292.2022.2142883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Indexed: 06/10/2023]
Abstract
Polarizing microscopy brought about many advancements in the science of liquid crystals and other soft materials, including those of biological origin. Recent developments in optics and computer-based analysis enabled a new generation of quantitative polarizing microscopy which produces spatial maps of the optic axis. Unfortunately, most of the available approaches require a long acquisition time of multiple images which are then analyzed to produce the map. We describe a polychromatic polarizing microscope, which allows one to map the patterns of the optical axis in a single-shot exposure, thus enabling a fast temporal resolution. We present a comparative analysis of the new microscope with alternative techniques such as a conventional polarizing optical microscope and MicroImager of Hinds Instruments.
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Affiliation(s)
- Mojtaba Rajabi
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Oleg Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA
- Department of Physics, Kent State University, Kent, OH 44242, USA
- Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
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10
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Ma LL, Li CY, Pan JT, Ji YE, Jiang C, Zheng R, Wang ZY, Wang Y, Li BX, Lu YQ. Self-assembled liquid crystal architectures for soft matter photonics. LIGHT, SCIENCE & APPLICATIONS 2022; 11:270. [PMID: 36100592 PMCID: PMC9470592 DOI: 10.1038/s41377-022-00930-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/14/2022] [Accepted: 07/09/2022] [Indexed: 06/03/2023]
Abstract
Self-assembled architectures of soft matter have fascinated scientists for centuries due to their unique physical properties originated from controllable orientational and/or positional orders, and diverse optic and photonic applications. If one could know how to design, fabricate, and manipulate these optical microstructures in soft matter systems, such as liquid crystals (LCs), that would open new opportunities in both scientific research and practical applications, such as the interaction between light and soft matter, the intrinsic assembly of the topological patterns, and the multidimensional control of the light (polarization, phase, spatial distribution, propagation direction). Here, we summarize recent progresses in self-assembled optical architectures in typical thermotropic LCs and bio-based lyotropic LCs. After briefly introducing the basic definitions and properties of the materials, we present the manipulation schemes of various LC microstructures, especially the topological and topographic configurations. This work further illustrates external-stimuli-enabled dynamic controllability of self-assembled optical structures of these soft materials, and demonstrates several emerging applications. Lastly, we discuss the challenges and opportunities of these materials towards soft matter photonics, and envision future perspectives in this field.
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Affiliation(s)
- Ling-Ling Ma
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Chao-Yi Li
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Jin-Tao Pan
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Yue-E Ji
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Chang Jiang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Ren Zheng
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Ze-Yu Wang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Yu Wang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China.
| | - Bing-Xiang Li
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China.
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, 210023, China.
| | - Yan-Qing Lu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China.
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11
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Berdin A, Gill JR, Perivolari E, Kauppo J, Apostolopoulos V, D'Alessandro G, Kaczmarek M, Priimagi A. Analysis of light diffraction by azobenzene-based photoalignment layers. OPTICS EXPRESS 2022; 30:29495-29506. [PMID: 36299123 DOI: 10.1364/oe.464278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 06/18/2022] [Indexed: 06/16/2023]
Abstract
Photoalignment materials, such as the azobenzene-based PAAD series studied here, are becoming increasingly important in liquid crystal-based optical devices and displays. Yet their properties and, in particular, their response to light, are still not fully understood. We investigate, experimentally and theoretically, the photoinduced birefringence, the order parameter and the formation of surface relief gratings, as well as the diffraction caused by them. We show that some of the azobenzene PAAD materials are suitable for the formation of surface relief gratings with high modulation depth, while others exhibit strong photoinduced birefringence. The two effects are inversely correlated: the stronger the surface relief grating is, the weaker is photoinduced birefringence. Analytical formulas based on the Raman-Nath approximation and numerical simulations of Maxwell's equations are used to quantify the diffraction caused by the induced diffraction gratings, showing excellent agreement between theory and experiment.
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12
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Guan Z, Wang L, Bae J. Advances in 4D printing of liquid crystalline elastomers: materials, techniques, and applications. MATERIALS HORIZONS 2022; 9:1825-1849. [PMID: 35504034 DOI: 10.1039/d2mh00232a] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Liquid crystalline elastomers (LCEs) are polymer networks exhibiting anisotropic liquid crystallinity while maintaining elastomeric properties. Owing to diverse polymeric forms and self-alignment molecular behaviors, LCEs have fascinated state-of-the-art efforts in various disciplines other than the traditional low-molar-mass display market. By patterning order to structures, LCEs demonstrate reversible high-speed and large-scale actuations in response to external stimuli, allowing for close integration with 4D printing and architectures of digital devices, which is scarcely observed in homogeneous soft polymer networks. In this review, we collect recent advances in 4D printing of LCEs, with emphases on synthesis and processing methods that enable microscopic changes in the molecular orientation and hence macroscopic changes in the properties of end-use objects. Promising potentials of printed complexes include fields of soft robotics, optics, and biomedical devices. Within this scope, we elucidate the relationships among external stimuli, tailorable morphologies in mesophases of liquid crystals, and programmable topological configurations of printed parts. Lastly, perspectives and potential challenges facing 4D printing of LCEs are discussed.
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Affiliation(s)
- Zhecun Guan
- Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA.
| | - Ling Wang
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, P. R. China.
| | - Jinhye Bae
- Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA.
- Chemical Engineering Program, University of California San Diego, La Jolla, CA 92093, USA
- Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093, USA
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13
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Park G, Suh A, Zhao H, Lee C, Choi YS, Smalyukh II, Yoon DK. Fabrication of Arrays of Topological Solitons in Patterned Chiral Liquid Crystals for Real-Time Observation of Morphogenesis. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201749. [PMID: 35661284 DOI: 10.1002/adma.202201749] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Topological solitons have knotted continuous field configurations embedded in a uniform background, and occur in cosmology, biology, and electromagnetism. However, real-time observation of their morphogenesis and dynamics is still challenging because their size and timescale are enormously large or tiny. Liquid crystal (LC) structures are promising candidates for a model-system to study the morphogenesis of topological solitons, enabling direct visualization due to the proper size and timescale. Here, a new way is found to rationalize the real-time observation of the generation and transformation of topological solitons using cholesteric LCs confined in patterned substrates. The experimental demonstration shows the topologically protected structures arise via the transformation of topological defects. Numerical modeling based on minimization of free energy closely reconstructs the experimental findings. The fundamental insights obtained from the direct observations pose new theoretical challenges in understanding the morphogenesis of different types of topological solitons within a broad range of scales.
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Affiliation(s)
- Geonhyeong Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Ahram Suh
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Hanqing Zhao
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Changjae Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Yun-Seok Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Ivan I Smalyukh
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
- Materials Science and Engineering Program, University of Colorado, Boulder, CO, 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO, 80309, USA
| | - Dong Ki Yoon
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
- KAIST Institute for Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
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14
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Fang Q, Liu J, Yan Z, Deng Q, Pang H, Lv Y, Sun X, Chen J, Jiang H, Yin S. Liquid-crystal-polymer binary diffractive optical elements with a sub-micrometer feature size realized by a contact polarization holography. OPTICS LETTERS 2022; 47:3195-3198. [PMID: 35776583 DOI: 10.1364/ol.461386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
In this Letter, a contact polarization holographic photoalignment method is proposed. In the holographic recording, a phase mask is contacted with a photoalignment film, making light carrying wavefront information interfere with reference light in the near-field region to realize polarization holographic pattern recording with a sub-micrometer feature size. The relevant theoretical derivation is given, and holographic recording of a 0.4 µm feature-size phase mask is realized. The proposed method can conveniently realize liquid-crystal binary diffractive optical elements with a sub-micrometer feature size. Off-axis diffraction can also be realized by superimposing the grating information by changing the angle between the substrate and the interference light.
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15
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Aranson IS. Bacterial active matter. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 85:076601. [PMID: 35605446 DOI: 10.1088/1361-6633/ac723d] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
Bacteria are among the oldest and most abundant species on Earth. Bacteria successfully colonize diverse habitats and play a significant role in the oxygen, carbon, and nitrogen cycles. They also form human and animal microbiota and may become sources of pathogens and a cause of many infectious diseases. Suspensions of motile bacteria constitute one of the most studied examples of active matter: a broad class of non-equilibrium systems converting energy from the environment (e.g., chemical energy of the nutrient) into mechanical motion. Concentrated bacterial suspensions, often termed active fluids, exhibit complex collective behavior, such as large-scale turbulent-like motion (so-called bacterial turbulence) and swarming. The activity of bacteria also affects the effective viscosity and diffusivity of the suspension. This work reports on the progress in bacterial active matter from the physics viewpoint. It covers the key experimental results, provides a critical assessment of major theoretical approaches, and addresses the effects of visco-elasticity, liquid crystallinity, and external confinement on collective behavior in bacterial suspensions.
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Affiliation(s)
- Igor S Aranson
- Departments of Biomedical Engineering, Chemistry, and Mathematics, Pennsylvania State University, University Park, PA 16802, United States of America
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16
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Nys I, Berteloot B, Neyts K. Photoaligned Liquid Crystal Devices with Switchable Hexagonal Diffraction Patterns. MATERIALS 2022; 15:ma15072453. [PMID: 35407785 PMCID: PMC8999608 DOI: 10.3390/ma15072453] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 02/01/2023]
Abstract
Highly efficient optical diffraction can be realized with the help of micrometer-thin liquid crystal (LC) layers with a periodic modulation of the director orientation. Electrical tunability is easily accessible due to the strong stimuli-responsiveness in the LC phase. By using well-designed photoalignment patterns at the surfaces, we experimentally stabilize two dimensional periodic LC configurations with switchable hexagonal diffraction patterns. The alignment direction follows a one-dimensional periodic rotation at both substrates, but with a 60° or 120° rotation between both grating vectors. The resulting LC configuration is studied with the help of polarizing optical microscopy images and the diffraction properties are measured as a function of the voltage. The intricate bulk director configuration is revealed with the help of finite element Q-tensor simulations. Twist conflicts induced by the surface anchoring are resolved by introducing regions with an out-of-plane tilt in the bulk. This avoids the need for singular disclinations in the structures and gives rise to voltage induced tuning without hysteretic behavior.
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17
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Zhang R, Mozaffari A, de Pablo JJ. Logic operations with active topological defects. SCIENCE ADVANCES 2022; 8:eabg9060. [PMID: 35196084 PMCID: PMC8865799 DOI: 10.1126/sciadv.abg9060] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 12/30/2021] [Indexed: 05/31/2023]
Abstract
Logic operations performed by semiconductor-based transistors are the basis of modern computing. There is considerable interest in creating autonomous materials systems endowed with the capability to make decisions. In this work, we introduce the concept of using topological defects in active matter to perform logic operations. When an extensile active stress in a nematic liquid crystal is turned on, +1/2 defects can self-propel, in analogy to electron transport under a voltage gradient. By relying on hydrodynamic simulations of active nematics, we demonstrate that patterns of activity, when combined with surfaces imparting certain orientations, can be used to control the formation and transport of +1/2 defects. We further show that asymmetric high- and low-activity patterns can be used to create effective defect gates, tunnels, and amplifiers. The proposed active systems offer the potential to perform computations and transmit information in active soft materials, including actin-, tubulin-, and cell-based systems.
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Affiliation(s)
- Rui Zhang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR
| | - Ali Mozaffari
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- OpenEye Scientific Software, Inc., 9 Bisbee Court Suite D, Santa Fe, New Mexico 87508, USA
| | - Juan J. de Pablo
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
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18
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Stebryte M. Reflective optical components based on chiral liquid crystal for head-up displays. LIQUID CRYSTALS TODAY 2022. [DOI: 10.1080/1358314x.2021.2036431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Migle Stebryte
- LCP Group, ELIS Department, Ghent University, Ghent, Belgium
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19
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Chen J, Akomolafe OI, Dhakal NP, Pujyam M, Skalli O, Jiang J, Peng C. Nematic Templated Complex Nanofiber Structures by Projection Display. ACS APPLIED MATERIALS & INTERFACES 2022; 14:7230-7240. [PMID: 35084814 DOI: 10.1021/acsami.1c20305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Oriented arrays of nanofibers are ubiquitous in nature and have been widely used in recreation of the biological functions such as bone and muscle tissue regenerations. However, it remains a challenge to produce nanofiber arrays with a complex organization by using current fabrication techniques such as electrospinning and extrusion. In this work, we propose a method to fabricate the complex organization of nanofiber structures templated by a spatially varying ordered liquid crystal host, which follows the pattern produced by a maskless projection display system. By programming the synchronization of the rotated polarizer and projected segments with different shapes, various configurations of nanofiber organization ranging from a single to two-dimensional lattice of arbitrary topological defects are created in a deterministic manner. The nanofiber arrays can effectively guide and promote neurite outgrowth. The application of nanofibers with arced profiles and topological defects on neural tissue organization is also demonstrated. This finding, combined with the versatility and programmability of nanofiber structures, suggests that they will help solve challenges in nerve repair, neural regeneration, and other related tissue engineering fields.
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Affiliation(s)
- Juan Chen
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Oluwafemi Isaac Akomolafe
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Netra Prasad Dhakal
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Mahesh Pujyam
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Omar Skalli
- Department of Biology, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Jinghua Jiang
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Chenhui Peng
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
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20
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Chen J, Akomolafe OI, Jiang J, Peng C. Light-Actuated Liquid Crystal Elastomer Prepared by Projection Display. MATERIALS (BASEL, SWITZERLAND) 2021; 14:7245. [PMID: 34885398 PMCID: PMC8658156 DOI: 10.3390/ma14237245] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022]
Abstract
Soft materials with programmability have been widely used in drug delivery, tissue engineering, artificial muscles, biosensors, and related biomedical engineering applications. Liquid crystal elastomers (LCEs) can easily morph into three-dimensional (3D) shapes by external stimuli such as light, heat, and humidity. In order to program two-dimensional (2D) LCE sheets into desired 3D morphologies, it is critical to precisely control the molecular orientations in LCE. In this work, we propose a simple photopatterning method based on a maskless projection display system to create spatially varying molecular orientations in LCE films. By designing different synchronized rotations of the polarizer and projected images, diverse configurations ranging from individual to 2D lattice of topological defects are fabricated. The proposed technique significantly simplified the photopatterning procedure without using fabricated masks or waveplates. Shape transformations such as a cone and a truncated square pyramid, and functionality mimicking the responsive Mimosa Pudica are demonstrated in the fabricated LCE films. The programmable LCE morphing behaviors demonstrated in this work will open opportunities in soft robotics and smart functional devices.
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Affiliation(s)
| | | | - Jinghua Jiang
- Department of Physics and Materials Science, The University of Memphis, Memphis, TN 38152, USA; (J.C.); (O.I.A.)
| | - Chenhui Peng
- Department of Physics and Materials Science, The University of Memphis, Memphis, TN 38152, USA; (J.C.); (O.I.A.)
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21
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Guo Y, Zhang J, Hu W, Khan MTA, Sitti M. Shape-programmable liquid crystal elastomer structures with arbitrary three-dimensional director fields and geometries. Nat Commun 2021; 12:5936. [PMID: 34642352 PMCID: PMC8511085 DOI: 10.1038/s41467-021-26136-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 09/08/2021] [Indexed: 11/09/2022] Open
Abstract
Liquid crystal elastomers exhibit large reversible strain and programmable shape transformations, enabling various applications in soft robotics, dynamic optics, and programmable origami and kirigami. The morphing modes of these materials depend on both their geometries and director fields. In two dimensions, a pixel-by-pixel design has been accomplished to attain more flexibility over the spatial resolution of the liquid crystal response. Here we generalize this idea in two steps. First, we create independent, cubic light-responsive voxels, each with a predefined director field orientation. Second, these voxels are in turn assembled to form lines, grids, or skeletal structures that would be rather difficult to obtain from an initially connected material sample. In this way, the orientation of the director fields can be made to vary at voxel resolution to allow for programmable optically- or thermally-triggered anisotropic or heterogeneous material responses and morphology changes in three dimensions that would be impossible or hard to implement otherwise.
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Affiliation(s)
- Yubing Guo
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Institute of Engineering Medicine, Beijing Institute of Technology, 100081, Beijing, China
| | - Jiachen Zhang
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong SAR, China
| | - Wenqi Hu
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Muhammad Turab Ali Khan
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.
- Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland.
- School of Medicine and College of Engineering, Koç University, 34450, Istanbul, Turkey.
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22
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Recent Advances in Photoalignment Liquid Crystal Polarization Gratings and Their Applications. CRYSTALS 2021. [DOI: 10.3390/cryst11080900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Liquid crystal (LC) circular polarization gratings (PGs), also known as Pancharatnam–Berry (PB) phase deflectors, are diffractive waveplates with linearly changed optical anisotropy axes. Due to the high diffraction efficiency, polarization selectivity character, and simple fabrication process, photoalignment LC PGs have been widely studied and developed especially in polarization management and beam split. In this review paper, we analyze the physical principles, show the exposure methods and fabrication process, and present relevant promising applications in photonics and imaging optics.
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23
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Lavrentovich OD. Design of nematic liquid crystals to control microscale dynamics. LIQUID CRYSTALS REVIEWS 2021; 8:59-129. [PMID: 34956738 PMCID: PMC8698256 DOI: 10.1080/21680396.2021.1919576] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/11/2021] [Indexed: 05/25/2023]
Abstract
The dynamics of small particles, both living such as swimming bacteria and inanimate, such as colloidal spheres, has fascinated scientists for centuries. If one could learn how to control and streamline their chaotic motion, that would open technological opportunities in the transformation of stored or environmental energy into systematic motion, with applications in micro-robotics, transport of matter, guided morphogenesis. This review presents an approach to command microscale dynamics by replacing an isotropic medium with a liquid crystal. Orientational order and associated properties, such as elasticity, surface anchoring, and bulk anisotropy, enable new dynamic effects, ranging from the appearance and propagation of particle-like solitary waves to self-locomotion of an active droplet. By using photoalignment, the liquid crystal can be patterned into predesigned structures. In the presence of the electric field, these patterns enable the transport of solid and fluid particles through nonlinear electrokinetics rooted in anisotropy of conductivity and permittivity. Director patterns command the dynamics of swimming bacteria, guiding their trajectories, polarity of swimming, and distribution in space. This guidance is of a higher level of complexity than a simple following of the director by rod-like microorganisms. Namely, the director gradients mediate hydrodynamic interactions of bacteria to produce an active force and collective polar modes of swimming. The patterned director could also be engraved in a liquid crystal elastomer. When an elastomer coating is activated by heat or light, these patterns produce a deterministic surface topography. The director gradients define an activation force that shapes the elastomer in a manner similar to the active stresses triggering flows in active nematics. The patterned elastomer substrates could be used to define the orientation of cells in living tissues. The liquid-crystal guidance holds a major promise in achieving the goal of commanding microscale active flows.
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Affiliation(s)
- Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Department of Physics, Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
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24
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Abstract
Stimuli-responsive materials that exhibit a mechanical response to specific biological conditions are of considerable interest for responsive, implantable medical devices. Herein, we report the synthesis, processing and characterization of oxidation-responsive liquid crystal elastomers that demonstrate programmable shape changes in response to reactive oxygen species. Direct ink writing (DIW) is used to fabricate Liquid Crystal Elastomers (LCEs) with programmed molecular orientation and anisotropic mechanical properties. LCE structures were immersed in different media (oxidative, basic and saline) at body temperature to measure in vitro degradation. Oxidation-sensitive hydrophobic thioether linkages transition to hydrophilic sulfoxide and sulfone groups. The introduction of these polar moieties brings about anisotropic swelling of the polymer network in an aqueous environment, inducing complex shape changes. 3D-printed uniaxial strips exhibit 8% contraction along the nematic director and 16% orthogonal expansion in oxidative media, while printed LCEs azimuthally deform into cones 19 times their original thickness. Ultimately, these LCEs degrade completely. In contrast, LCEs subjected to basic and saline solutions showed no apparent response. These oxidation-responsive LCEs with programmable shape changes may enable a wide range of applications in target specific drug delivery systems and other diagnostic and therapeutic tools.
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25
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Zhu S, Tang Y, Lin C, Liu XY, Lin Y. Recent Advances in Patterning Natural Polymers: From Nanofabrication Techniques to Applications. SMALL METHODS 2021; 5:e2001060. [PMID: 34927826 DOI: 10.1002/smtd.202001060] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/09/2021] [Indexed: 06/14/2023]
Abstract
The development of a flexible and efficient strategy to precisely fabricate polymer patterns is increasingly significant for many research areas, especially for cell biology, pharmaceutical science, tissue engineering, soft photonics, and bioelectronics. Recent advances of patterning natural polymers using various nanofabrication techniques, including photolithography, electron-beam lithography, dip-pen nanolithography, inkjet printing, soft lithography, and nanoimprint lithography are discussed here. Integrating nanofabrication techniques with naturally derived macromolecules provides a feasible route for transforming these polymer materials into versatile and sophisticated devices while maintaining their intrinsic and excellent properties. Furthermore, the corresponding applications of these natural polymer patterns generated by the above techniques are elaborated. In the end, a summary of this promising research field is offered and an outlook for the future is given. It is expected that advances in precise spatial patterns of natural polymers would provide new avenues for various applications, such as tissue engineering, flexible electronics, biomedical diagnosis, and soft photonics.
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Affiliation(s)
- Shuihong Zhu
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen, 361005, China
| | - Yonghua Tang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen, 361005, China
| | - Changxu Lin
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen, 361005, China
| | - Xiang Yang Liu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Youhui Lin
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen, 361005, China
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26
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Nys I. Patterned surface alignment to create complex three-dimensional nematic and chiral nematic liquid crystal structures. LIQUID CRYSTALS TODAY 2021. [DOI: 10.1080/1358314x.2020.1886780] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Inge Nys
- LCP Group, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
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27
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Perera K, Nemati A, Mann EK, Hegmann T, Jákli A. Converging Microlens Array Using Nematic Liquid Crystals Doped with Chiral Nanoparticles. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4574-4582. [PMID: 33411492 DOI: 10.1021/acsami.0c21044] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Nematic liquid crystals of achiral molecules or racemic mixtures of chiral ones form flat films when suspended in submillimeter size grids and submerged under water. Recently, it has been shown (Popov et al., 2017) that films of nematic liquid crystals doped with chiral molecules adopt biconvex lens shapes underwater. The curved shape together with degenerate planar anchoring leads to a radial variation of the optical axis along the plane of the film, providing a Pancharatnam-Berry-type phase lens that modifies geometric optical imaging. Here, we describe nematic liquid crystal microlenses formed by the addition of chiral nanoparticles. It is found that the helical twisting power of the nanoparticles, the key factor to form the lens, is about 400 μm-1, greater than that of the strongest molecular chiral dopants. We demonstrate imaging capabilities and measure the shape as well as the focal length of the chiral nanoparticle-doped liquid crystal lens. We show that measuring the shape of the lens allows one to calculate the helical pitch of the chiral nematic liquid crystal and thus determine the helical twisting power of the chiral ligand-capped nanoparticles. Such measurements require the use of only nanograms of chiral nanoparticles, which is 3 orders of magnitude less than that required by conventional techniques. Since NPs are sensitive to external stimuli such as light and electric and magnetic fields, the use of chiral NPs may allow the achievement of tunable optical properties for such microlens arrays.
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Affiliation(s)
- Kelum Perera
- Physics Department, Kent State University, Kent, Ohio 44242, United States
| | - Ahlam Nemati
- Advanced Materials and Liquid Crystal Institute Kent State University, Kent, Ohio 44242, United States
- Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, United States
| | - Elizabeth K Mann
- Physics Department, Kent State University, Kent, Ohio 44242, United States
- Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, United States
| | - Torsten Hegmann
- Advanced Materials and Liquid Crystal Institute Kent State University, Kent, Ohio 44242, United States
- Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, United States
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
- Brain Health Research Institute, Kent State University, Kent, Ohio 44242, United States
| | - Antal Jákli
- Physics Department, Kent State University, Kent, Ohio 44242, United States
- Advanced Materials and Liquid Crystal Institute Kent State University, Kent, Ohio 44242, United States
- Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, United States
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Abstract
Liquid crystals are complex fluids that allow exquisite control of light propagation thanks to their orientational order and optical anisotropy. Inspired by recent advances in liquid-crystal photo-patterning technology, we propose a soft-matter platform for assembling topological photonic materials that holds promise for protected unidirectional waveguides, sensors, and lasers. Crucial to our approach is to use spatial variations in the orientation of the nematic liquid-crystal molecules to emulate the time modulations needed in a so-called Floquet topological insulator. The varying orientation of the nematic director introduces a geometric phase that rotates the local optical axes. In conjunction with suitably designed structural properties, this geometric phase leads to the creation of topologically protected states of light. We propose and analyze in detail soft photonic realizations of two iconic topological systems: a Su-Schrieffer-Heeger chain and a Chern insulator. The use of soft building blocks potentially allows for reconfigurable systems that exploit the interplay between topological states of light and the underlying responsive medium.
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29
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Abstract
Photo-alignment is a versatile tool to pattern the alignment at the confining substrates in a liquid crystal (LC) cell. Arbitrary alignment patterns can be created by using projection with a spatial light modulator (SLM) for the illumination. We demonstrate that a careful design of the alignment patterns allows the stabilization of topological solitons in nematic liquid crystal (NLC) cells, without the need for chirality or strong confinement. The created LC configurations are stabilized by the anchoring conditions imposed at the substrates. The photo-aligned background at both substrates is uniformly planar aligned, and ring-shaped regions with a 180° azimuthal rotation are patterned with an opposite sense of rotation at the top and bottom substrate. A disclination-free structure containing a closed ring of vertically oriented directors is formed when the patterned rings at the top and bottom substrate overlap. Thanks to the topological stability, a vertical director orientation in the bulk is observed even when the centra of both patterned rings are shifted over relatively large distances. The combination of numerical simulations with experimental measurements allows identification of the 3D director configuration in the bulk. A finite element (FE) Q-tensor simulation model is applied to find the equilibrium director configuration and optical simulations are used to confirm the correspondence with experimental microscopy measurements. The created LC configurations offer opportunities in the field of optical devices, light guiding and switching, particle trapping and studies of topological LC structures.
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30
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Guo Y, Shahsavan H, Sitti M. 3D Microstructures of Liquid Crystal Networks with Programmed Voxelated Director Fields. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002753. [PMID: 32767434 PMCID: PMC7610484 DOI: 10.1002/adma.202002753] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/03/2020] [Indexed: 05/17/2023]
Abstract
The shape-shifting behavior of liquid crystal networks (LCNs) and elastomers (LCEs) is a result of an interplay between their initial geometrical shape and their molecular alignment. For years, reliance on either one-step in situ or two-step film processing techniques has limited the shape-change transformations from 2D to 3D geometries. The combination of various fabrication techniques, alignment methods, and chemical formulations developed in recent years has introduced new opportunities to achieve 3D-to-3D shape-transformations in large scales, albeit the precise control of local molecular alignment in microscale 3D constructs remains a challenge. Here, the voxel-by-voxel encoding of nematic alignment in 3D microstructures of LCNs produced by two-photon polymerization using high-resolution topographical features is demonstrated. 3D LCN microstructures (suspended films, coils, and rings) with designable 2D and 3D director fields with a resolution of 5 µm are achieved. Different shape transformations of LCN microstructures with the same geometry but dissimilar molecular alignments upon actuation are elicited. This strategy offers higher freedom in the shape-change programming of 3D LCN microstructures and expands their applicability in emerging technologies, such as small-scale soft robots and devices and responsive surfaces.
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Affiliation(s)
- Yubing Guo
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Hamed Shahsavan
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany; Department of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
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31
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Chen P, Wei BY, Hu W, Lu YQ. Liquid-Crystal-Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903665. [PMID: 31566267 DOI: 10.1002/adma.201903665] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/07/2019] [Indexed: 06/10/2023]
Abstract
Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, the geometric phase, induced by the photonic spin-orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli-responsive self-assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC-mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC-based transmissive planar optical elements and chiral LC-based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.
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Affiliation(s)
- Peng Chen
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Bing-Yan Wei
- MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Wei Hu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
- Institute for Smart Liquid Crystals, JITRI, Changshu, 215500, China
| | - Yan-Qing Lu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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32
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Ferroelectric nematic liquid crystal, a century in waiting. Proc Natl Acad Sci U S A 2020; 117:14629-14631. [PMID: 32541021 DOI: 10.1073/pnas.2008947117] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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33
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Berteloot B, Nys I, Poy G, Beeckman J, Neyts K. Ring-shaped liquid crystal structures through patterned planar photo-alignment. SOFT MATTER 2020; 16:4999-5008. [PMID: 32436547 DOI: 10.1039/d0sm00308e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Patterned liquid crystal (LC) configurations find widespread applications in functional devices such as lenses, gratings, displays and soft-robots. In combination with external stimuli such as an applied electric field, photo-alignment at the surfaces offers an attractive way to stabilize different LC structures in the bulk of a device. Herein, a planar LC cell is developed using a photo-alignment layer at the bottom substrate and a rubbed nylon film at the top substrate. Patterned planar photo-alignment is achieved by modulating the linear polarization with a spatial light modulator (SLM) and projecting the pattern onto the bottom substrate. A ring pattern is written into the photo-alignment layer with a continuous rotation between an inner radius and an outer radius. In the other regions the alignment is parallel to the rubbing direction at the top substrate. Four different LC configurations are observed: structure A in which a ring-shaped region is formed with an out of plane (vertical) orientation perpendicular to the substrate, structure B which has a single disclination loop and a 180° twist at the inner region of the photo-patterned ring (r < rin), structure C which has no discontinuities but a 360° twist in the inner region of the photo-patterned ring (r < rin) and structure D with 2 disclination loops. The LC director configuration for all 4 structures is simulated through finite element (FE) Q-tensor simulations and the optical transmission for each structure is simulated using a generalized beam propagation method.
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Affiliation(s)
- Brecht Berteloot
- Liquid Crystals & Photonics Group, Department of Electronics and Information Systems, Ghent University, Technologiepark-Zwijnaarde 126, B-9052 Ghent, Belgium.
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Jiang J, Dhakal NP, Guo Y, Andre C, Thompson L, Skalli O, Peng C. Controlled Dynamics of Neural Tumor Cells by Templated Liquid Crystalline Polymer Networks. Adv Healthc Mater 2020; 9:e2000487. [PMID: 32378330 DOI: 10.1002/adhm.202000487] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/09/2020] [Indexed: 01/25/2023]
Abstract
The ability to control the alignment and organization of cell populations has great potential for tissue engineering and regenerative medicine. A variety of approaches such as nano/microtopographical patterning, mechanical loading, and nanocomposite synthesis have been developed to engineer scaffolds able to control cellular properties and behaviors. In this work, a patterned liquid crystal polymer network (LCN) film is synthesized by using a nematic liquid crystal template in which the molecular orientations are predesigned by photopatterning technique. Various configurations of polymer networks such as linear and circular patterns are created. When neural tumor cells are plated onto the templated LCN films, the cell alignment, migration, and proliferation are directed in both linear and curvilinear fashions following the pattern of the aligned polymer chains. A complex LCN pattern with zigzag geometry is also fabricated and found to be capable of controlling cell alignment and collective cellular organization. The demonstrated control of cell dynamics and organization by LCN films with various molecular alignments opens new opportunities to design scaffolds to control cultured cell organization in a manner resembling that found in tissues and to develop novel advanced materials for nerve repair, tissue engineering, and regenerative medicine applications.
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Affiliation(s)
- Jinghua Jiang
- Department of Physics and Materials ScienceThe University of Memphis Memphis TN 38152 USA
| | - Netra Prasad Dhakal
- Department of Physics and Materials ScienceThe University of Memphis Memphis TN 38152 USA
| | - Yubing Guo
- Advanced Materials and Liquid Crystal InstituteKent State University Kent OH 44242 USA
| | - Christian Andre
- Department of Physics and Materials ScienceThe University of Memphis Memphis TN 38152 USA
| | - Lauren Thompson
- Department of BiologyThe University of Memphis Memphis TN 38152 USA
| | - Omar Skalli
- Department of BiologyThe University of Memphis Memphis TN 38152 USA
| | - Chenhui Peng
- Department of Physics and Materials ScienceThe University of Memphis Memphis TN 38152 USA
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Dhakal NP, Jiang J, Guo Y, Peng C. Self-Assembly of Aqueous Soft Matter Patterned by Liquid-Crystal Polymer Networks for Controlling the Dynamics of Bacteria. ACS APPLIED MATERIALS & INTERFACES 2020; 12:13680-13685. [PMID: 32118403 DOI: 10.1021/acsami.0c00746] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The study of controlling the molecular self-assembly of aqueous soft matter is a fundamental scheme across multiple disciplines such as physics, chemistry, biology, and materials science. In this work, we use liquid-crystal polymer networks (LCNs) to control the superstructures of one aqueous soft material called lyotropic chromonic liquid crystals (LCLCs), which shows spontaneous orientational order by stacking the plank-like molecules into elongated aggregates. We synthesize a layer of patterned LCN films by a nematic liquid-crystal host in which the spatially varying molecular orientations are predesigned by plasmonic photopatterning. We demonstrate that the LCLC aggregates are oriented parallel to the polymer filaments of the LCN film. This patterned aqueous soft material shows immediate application for controlling the dynamics of swimming bacteria. The demonstrated control of the supramolecular assembly of aqueous soft matter by using a stimuli-responsive LCN film will find applications in designing dynamic advanced materials for bioengineering applications.
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Affiliation(s)
- Netra Prasad Dhakal
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Jinghua Jiang
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
| | - Yubing Guo
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, United States
| | - Chenhui Peng
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, United States
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Babakhanova G, Krieger J, Li BX, Turiv T, Kim MH, Lavrentovich OD. Cell alignment by smectic liquid crystal elastomer coatings with nanogrooves. J Biomed Mater Res A 2020; 108:1223-1230. [PMID: 32034939 DOI: 10.1002/jbm.a.36896] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/23/2020] [Accepted: 02/04/2020] [Indexed: 11/07/2022]
Abstract
Control of cells behavior through topography of substrates is an important theme in biomedical applications. Among many materials used as substrates, polymers show advantages since they can be tailored by chemical functionalization. Fabrication of polymer substrates with nano- and microscale topography requires processing by lithography, microprinting, etching, and so forth. In this work, we introduce a different approach based on anisotropic elastic properties of polymerized smectic A (SmA) liquid crystal elastomer (LCE). When the SmA liquid crystal coating is deposited onto a substrate with planar alignment of the molecules, it develops nanogrooves at its free surface. After photopolymerization, these nanogrooves show an excellent ability to align human dermal fibroblasts over large areas. The alignment quality is good for both bare SmA LCE substrates and for substrates coated with fibronectin. The SmA LCE nano-topographies show a high potential for tissue engineering.
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Affiliation(s)
- Greta Babakhanova
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio
| | - Jess Krieger
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Bing-Xiang Li
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio
| | - Taras Turiv
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio
| | - Min-Ho Kim
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio
- Department of Physics, Kent State University, Kent, Ohio
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Harkai S, Murray BS, Rosenblatt C, Kralj S. Electric field-driven reconfigurable multistable topological defect patterns. PHYSICAL REVIEW RESEARCH 2020; 2:013176. [PMID: 33870201 PMCID: PMC8051152 DOI: 10.1103/physrevresearch.2.013176] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Topological defects appear in symmetry breaking phase transitions and are ubiquitous throughout Nature. As an ideal testbed for their study, defect configurations in nematic liquid crystals (NLCs) could be exploited in a rich variety of technological applications. Here we report on robust theoretical and experimental investigations in which an external electric field is used to switch between pre-determined stable chargeless disclination patterns in a nematic cell, where the cell is sufficiently thick that the disclinations start and terminate at the same surface. The different defect configurations are stabilised by a master substrate that enforces a lattice of surface defects exhibiting zero total topological charge value. Theoretically, we model disclination configurations using a Landau-de Gennes phenomenological model. Experimentally, we enable diverse defect patterns by implementing an in-house-developed Atomic Force Measurement scribing method, where NLC configurations are monitored via polarised optical microscopy. We show numerically and experimentally that an "alphabet" of up to 18 unique line defect configurations can be stabilised in a 4x4 lattice of alternating s=±1 surface defects, which can be "rewired" multistably using appropriate field manipulation. Our proof-of-concept mechanism may lead to a variety of applications, such as multistable optical displays and rewirable nanowires. Our studies also are of interest from a fundamental perspective. We demonstrate that a chargeless line could simultaneously exhibit defect-antidefect properties. Consequently, a pair of such antiparallel disclinations exhibits an attractive interaction. For a sufficiently closely-spaced pair of substrate-pinned defects, this interaction could trigger rewiring, or annihilation if defects are depinned.
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Affiliation(s)
- Saša Harkai
- Condensed Matter Physics, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Bryce S. Murray
- Department of Physics, Case Western Reserve University Cleveland, Ohio 44106, USA
| | - Charles Rosenblatt
- Department of Physics, Case Western Reserve University Cleveland, Ohio 44106, USA
| | - Samo Kralj
- Condensed Matter Physics, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
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Ferris AJ, Afghah S, Selinger RLB, Selinger JV, Rosenblatt C. Electric field-induced crossover from 3D to 2D topological defects in a nematic liquid crystal: experimental verification. SOFT MATTER 2020; 16:642-650. [PMID: 31693053 PMCID: PMC6981022 DOI: 10.1039/c9sm01733j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A substrate was patterned with two pairs of half-integer strength topological defects, (+1/2, +1/2) and (+1/2, -1/2). In a sufficiently thick cell, a disclination line runs in an arch above the substrate connecting the two half integer defects within each pair. The director around the disclination line for the like-sign pair must rotate in 3D, whereas for the opposite-sign defect pair the director lies in the xy-plane parallel to the substrate. For a negative dielectric anisotropy nematic, an electric field applied normal to the substrate drives the director into the xy-plane, forcing the arch of the disclination line of the like-sign pair to become extended along the z-axis. For sufficiently large field the arch splits, resulting in two nearly parallel disclination lines traversing the cell from one substrate to the other. The opposite-sign defect pair is largely unaffected by the electric field as the director already lies in the xy-plane. Experimental results are presented, which are consistent with numerical simulations.
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Affiliation(s)
- Andrew J Ferris
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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Guo Y, Shahsavan H, Davidson ZS, Sitti M. Precise Control of Lyotropic Chromonic Liquid Crystal Alignment through Surface Topography. ACS APPLIED MATERIALS & INTERFACES 2019; 11:36110-36117. [PMID: 31532609 DOI: 10.1021/acsami.9b12943] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Many emerging applications, such as water-based electronic devices and biological sensors, require local control of anisotropic properties. Lyotropic chromonic liquid crystals (LCLCs) are an exciting class of materials, which are usually biocompatible and provide uniaxial anisotropy through a director field but, to date, remain difficult to control. In this work, we introduce a simple strategy to realize an arbitrary orientation of LCLCs director field in two dimensions (2D). Our alignment strategy relies on surface topographical micro/nanostructures fabricated by two-photon laser writing. We show that the alignment of LCLCs can be: (a) precisely controlled with a remarkable pixel resolution of 2.5 μm and (b) patterned into an arbitrary 2D alignment (e.g., +2 topological defect) by a pixelated design and arrangement of micro/nanostructures. Using a similar strategy, we achieve a patternable homeotropic alignment of LCLCs with nanopillars. Finally, we demonstrate that a self-assembled three-dimensional alignment of LCLCs can be obtained due to the versatility of our alignment strategy. Our demonstration of LCLC director field control, which is not only straightforward to achieve but also compatible with other conventional micro/nanofabrication techniques, will provide new opportunities for the manufacturing of LC-based electronic and biological devices.
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Affiliation(s)
- Yubing Guo
- Physical Intelligence Department , Max Planck Institute for Intelligent Systems , 70569 Stuttgart , Germany
| | - Hamed Shahsavan
- Physical Intelligence Department , Max Planck Institute for Intelligent Systems , 70569 Stuttgart , Germany
| | - Zoey S Davidson
- Physical Intelligence Department , Max Planck Institute for Intelligent Systems , 70569 Stuttgart , Germany
| | - Metin Sitti
- Physical Intelligence Department , Max Planck Institute for Intelligent Systems , 70569 Stuttgart , Germany
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40
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Pusovnik A, Aplinc J, Ravnik M. Optical properties of metamaterial split ring nematic colloids. Sci Rep 2019; 9:7025. [PMID: 31065025 PMCID: PMC6505528 DOI: 10.1038/s41598-019-43470-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/23/2019] [Indexed: 11/20/2022] Open
Abstract
The fabrication of 3D bulk metamaterials, optical materials with sub-wavelength building blocks, is an open challenge, along with the tuning of their optical properties, such as transmissivity or exit polarization where a possible approach is to embed liquid crystalline materials into metamaterials and use their tunable birefringence. In this work, we explore using numerical modelling the photonic properties of a composite of split ring resonator colloidal particles, dispersed in nematic liquid crystal, which was optimised to enable self-assembly fully. Specifically, using generalised FDTD simulations for light propagation in birefringent profiles, we demonstrate the photonic response of single particles, 2D and 3D colloidal crystals. The material transmittance is shown to exhibit clear resonant behaviour with the resonances tunable with the birefringence in the order of ~5%. Electric and magnetic field modes emergent on the particles are shown, as affected by the surrounding nematic birefringence, both the in the slit region of the split ring resonator (SRR) particles as well as around the particles. Observed photonic response is further explained by introducing basic equivalent LC circuits. Finally, this work is aimed at developing soft and fluid metamaterials, which exhibit optical anisotropy in the photonic response as a potent mechanism for controlling the flow of light at wavelength and even sub-wavelength scales.
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Affiliation(s)
- Anja Pusovnik
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia.
| | - Jure Aplinc
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
| | - Miha Ravnik
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
- J. Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
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Jiang M, Guo Y, Yu H, Zhou Z, Turiv T, Lavrentovich OD, Wei QH. Low f-Number Diffraction-Limited Pancharatnam-Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1808028. [PMID: 30907480 DOI: 10.1002/adma.201808028] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/06/2019] [Indexed: 06/09/2023]
Abstract
Microlenses are desired by a wide range of industrial applications while it is always challenging to make them with diffraction-limited quality. Here, it is shown that high-quality microlenses based on Pancharatnam-Berry (PB) phases can be made with liquid crystal polymers by using a plasmonic photopatterning technique. Based on the generalized Snell's law for the PB phases, PB microlenses with a range of focal lengths and f-numbers are designed and fabricated and their point-spread functions and ability to image micrometer-sized particles are carefully characterized. The results show that these PB microlenses with f-number down to 2 are all diffraction-limited. The capability of arraying these PB microlenses with 100% filling factor with a step-and-flash approach is further demonstrated.
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Affiliation(s)
- Miao Jiang
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Yubing Guo
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Hao Yu
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Ziyuan Zhou
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Taras Turiv
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
| | - Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
- Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - Qi-Huo Wei
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
- Department of Physics, Kent State University, Kent, OH, 44242, USA
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Babakhanova G, Yu H, Chaganava I, Wei QH, Shiller P, Lavrentovich OD. Controlled Placement of Microparticles at the Water-Liquid Crystal Elastomer Interface. ACS APPLIED MATERIALS & INTERFACES 2019; 11:15007-15013. [PMID: 30912438 DOI: 10.1021/acsami.8b22023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Controlled placement of microparticles is of prime importance in production of microscale superstructures. In this work, we demonstrate the remote control of microparticle placement using a photoactivated surface profile of a liquid crystal elastomer (LCE) coating. We employ light-responsive LCEs with preimposed patterns of molecular orientation (director) in the plane of coating. Upon UV illumination, these in-plane director distortions translate into deterministic topographic change of the LCE coating. Microparticles placed at the interface between the LCE coating and water, guided by gravity, gather at the bottom of photoinduced troughs. The effect is reversible: when the substrates are irradiated with visible light, the coatings become flat and the microparticle arrays disorganize again. The proposed noncontact manipulation of particles by photoactivated LCEs may be useful in development of drug delivery or tissue engineering applications.
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Affiliation(s)
| | | | - Irakli Chaganava
- Institute of Cybernetics of Georgian Technical University , Tbilisi 0186 , Georgia
- Georgian State Teaching University of Physical Education and Sport , Tbilisi 0162 , Georgia
| | | | - Paul Shiller
- Civil Engineering-Timken Engineered Surface Laboratory , The University of Akron , Akron 44325 , United States
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Nys I, Beeckman J, Neyts K. Voltage-controlled formation of short pitch chiral liquid crystal structures based on high-resolution surface topography. OPTICS EXPRESS 2019; 27:11492-11502. [PMID: 31052992 DOI: 10.1364/oe.27.011492] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 03/29/2019] [Indexed: 06/09/2023]
Abstract
Chiral nematic liquid crystals (CLCs) offer interesting perspectives for device applications and are fascinating materials to study because of their ability to self-assemble into complex structures. This work demonstrates that narrow lines of electron-beam resist on top of an ITO coated glass surface can dramatically influence the formation and growth of short pitch chiral superstructures in the bulk. By applying a voltage to the cell, directional growth of CLC structures along the corrugated surface can be controlled. Below the electric unwinding threshold, chiral structures start to grow along the grating lines with their helical axis parallel to the substrates. This results in a uniform lying helix-like structure at intermediate voltages and a chiral configuration with periodic undulations of the helical axis at low voltages.
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Li Y, Liu Y, Li S, Zhou P, Zhan T, Chen Q, Su Y, Wu ST. Single-exposure fabrication of tunable Pancharatnam-Berry devices using a dye-doped liquid crystal. OPTICS EXPRESS 2019; 27:9054-9060. [PMID: 31052714 DOI: 10.1364/oe.27.009054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
We report a non-interferometric single-exposure technique for fabricating Pancharatnam-Berry (PB) devices with arbitrary wavefronts, via photo-patterning an azo-dye doped LC with a two-dimensional linear polarization field, whose local polarization direction can be controlled by a spatial light modulator (SLM) on the pixel level. Upon one exposure, different local LC orientations are generated simultaneously. The non-interferometric approach is insensitive to environmental disturbance, and moreover, the dynamic phase mask on the SLM can be conveniently reconfigured by a computer. Our fabricated PB gratings, q-plates and hologram exhibit good optical performances. Such a simple yet reconfigurable fabrication method enables new PB devices to be developed, and it would open a new gateway towards widespread applications.
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Peng C, Lavrentovich OD. Liquid Crystals-Enabled AC Electrokinetics. MICROMACHINES 2019; 10:E45. [PMID: 30634568 PMCID: PMC6356904 DOI: 10.3390/mi10010045] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/01/2019] [Accepted: 01/01/2019] [Indexed: 11/17/2022]
Abstract
Phenomena of electrically driven fluid flows, known as electro-osmosis, and particle transport in a liquid electrolyte, known as electrophoresis, collectively form a subject of electrokinetics. Electrokinetics shows a great potential in microscopic manipulation of matter for various scientific and technological applications. Electrokinetics is usually studied for isotropic electrolytes. Recently it has been demonstrated that replacement of an isotropic electrolyte with an anisotropic, or liquid crystal (LC), electrolyte, brings about entirely new mechanisms of spatial charge formation and electrokinetic effects. This review presents the main features of liquid crystal-enabled electrokinetics (LCEK) rooted in the field-assisted separation of electric charges at deformations of the director that describes local molecular orientation of the LC. Since the electric field separates the charges and then drives the charges, the resulting electro-osmotic and electrophoretic velocities grow as the square of the applied electric field. We describe a number of related phenomena, such as alternating current (AC) LC-enabled electrophoresis of colloidal solid particles and fluid droplets in uniform and spatially-patterned LCs, swarming of colloids guided by photoactivated surface patterns, control of LCEK polarity through the material properties of the LC electrolyte, LCEK-assisted mixing at microscale, separation and sorting of small particles. LC-enabled electrokinetics brings a new dimension to our ability to manipulate dynamics of matter at small scales and holds a major promise for future technologies of microfluidics, pumping, mixing, sensing, and diagnostics.
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Affiliation(s)
- Chenhui Peng
- Department of Physics and Materials Science, The University of Memphis, Memphis, TN 38152, USA.
| | - Oleg D Lavrentovich
- Department of Physics and Chemical Physics Interdisciplinary Program, Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
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Abstract
Active matter is a wide class of nonequilibrium systems consisting of interacting self-propelled agents transducing the energy stored in the environment into mechanical motion. Numerous examples range from microscopic cytoskeletal filaments and swimming organisms (bacteria and unicellular algae), synthetic catalytic nanomotors, colloidal self-propelled Janus particles, to macroscopic bird flocks, fish schools, and even human crowds. Active matter demonstrates a remarkable tendency toward self-organization and development of collective states with the long-range spatial order. Furthermore, active materials exhibit properties that are not present in traditional materials like plastics or ceramics: self-repair, shape change, and adaptation. A suspension of microscopic swimmers, such as motile bacteria or self-propelled colloids (active suspensions), is possibly the simplest and the most explored realization of active matter. Recent studies of active suspensions revealed a wealth of unexpected behaviors, from a dramatic reduction of the effective viscosity, enhanced mixing and self-diffusion, rectification of chaotic motion, to artificial rheotaxis (drift against the imposed flow) and cross-stream migration. To date, most of the studies of active matter are performed in isotropic suspending medium, like water with the addition of some "fuel", e.g., nutrient for bacteria or H2O2 for catalytic bimetallic AuPt nanorods. A highly structured anisotropic suspending medium represented by lyotropic liquid crystal (water-soluble) opens enormous opportunities to control and manipulate active matter. Liquid crystals exhibit properties intermediate between solid and liquids; they may flow like a liquid but respond to deformations as a solid due to a crystal-like orientation of molecules. Liquid crystals doped by a small amount of active component represent a new class of composite materials (living liquid crystals or LLCs) with unusual mechanical and optical properties. LLCs demonstrate a variety of highly organized dynamic collective states, spontaneous formation of dynamic textures of topological defects (singularities of local molecular orientation), controlled and reconfigurable transport of cargo particles, manipulation of individual trajectories of microswimmers, and many others. Besides insights into fundamental mechanisms governing active materials, living liquid crystals may have intriguing applications, such as the design of new classes of soft adaptive bioinspired materials capable to respond to physical and chemical stimuli, such as light, magnetic, and electric fields, mechanical shear, airborne pollutants, and bacterial toxins. This Account details the most recent developments in the field of LLCs and discusses how the anisotropy of liquid crystals can be harnessed to control and manipulate active materials.
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Affiliation(s)
- Igor S. Aranson
- Departments of Biomedical Engineering, Chemistry and Mathematics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Amano R, Salamon P, Yokokawa S, Kobayashi F, Sasaki Y, Fujii S, Buka Á, Araoka F, Orihara H. Tunable two-dimensional polarization grating using a self-organized micropixelated liquid crystal structure. RSC Adv 2018; 8:41472-41479. [PMID: 35559295 PMCID: PMC9092010 DOI: 10.1039/c8ra08557a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/03/2018] [Indexed: 11/21/2022] Open
Abstract
Utilization of the self-organizing nature of soft materials is promising for fabricating micro- and nano-structures, which can be applied for optics. Because of the high birefringence, liquid crystals are especially suitable for optoelectronic applications such as beam steering and polarization conversion. On the other hand, most self-organized patterns in liquid crystals are one-dimensional and there are only a few examples of two dimensional systems. Here we study the light diffraction from a micro-pixelated pattern of a nematic liquid crystal which is formed by self-organization of topological defects. We demonstrate that the system works as a tunable two dimensional optical grating, which splits the incident laser beam and changes the polarization property. The intensity can be controlled by electrical voltages, which cause extinction of the zeroth-order beam. The polarization properties depend on the location of spots. The numerical calculation and the theoretical analysis not only support the experimental results but also unveil the uniqueness of the pixelated structure. A micro-pixelated pattern of a nematic liquid crystal formed by self-organization of topological defects is shown to work as a tunable two-dimensional optical grating.![]()
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Affiliation(s)
- Reo Amano
- Division of Applied Physics, Faculty of Engineering, Hokkaido University North 13 West 8, Kita-ku Sapporo Hokkaido 060-8628 Japan +81 (0)11 7066642
| | - Péter Salamon
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences H-1525 Budapest P. O. Box 49 Hungary.,RIKEN Center for Emergent Matter Science (CEMS) 2-1 Hirosawa Wako, Saitama 351-0198 Japan
| | - Shunsuke Yokokawa
- Division of Applied Physics, Faculty of Engineering, Hokkaido University North 13 West 8, Kita-ku Sapporo Hokkaido 060-8628 Japan +81 (0)11 7066642
| | - Fumiaki Kobayashi
- Division of Applied Physics, Faculty of Engineering, Hokkaido University North 13 West 8, Kita-ku Sapporo Hokkaido 060-8628 Japan +81 (0)11 7066642
| | - Yuji Sasaki
- Division of Applied Physics, Faculty of Engineering, Hokkaido University North 13 West 8, Kita-ku Sapporo Hokkaido 060-8628 Japan +81 (0)11 7066642
| | - Shuji Fujii
- Division of Applied Physics, Faculty of Engineering, Hokkaido University North 13 West 8, Kita-ku Sapporo Hokkaido 060-8628 Japan +81 (0)11 7066642
| | - Ágnes Buka
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences H-1525 Budapest P. O. Box 49 Hungary
| | - Fumito Araoka
- RIKEN Center for Emergent Matter Science (CEMS) 2-1 Hirosawa Wako, Saitama 351-0198 Japan
| | - Hiroshi Orihara
- Division of Applied Physics, Faculty of Engineering, Hokkaido University North 13 West 8, Kita-ku Sapporo Hokkaido 060-8628 Japan +81 (0)11 7066642
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48
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Kim DS, Čopar S, Tkalec U, Yoon DK. Mosaics of topological defects in micropatterned liquid crystal textures. SCIENCE ADVANCES 2018; 4:eaau8064. [PMID: 30480093 PMCID: PMC6251723 DOI: 10.1126/sciadv.aau8064] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/25/2018] [Indexed: 05/29/2023]
Abstract
Topological defects in the orientational order that appear in thin slabs of a nematic liquid crystal, as seen in the standard schlieren texture, behave as a random quasi-two-dimensional system with strong optical birefringence. We present an approach to creating and controlling the defects using air pillars, trapped by micropatterned holes in the silicon substrate. The defects are stabilized and positioned by the arrayed air pillars into regular two-dimensional lattices. We explore the effects of hole shape, lattice symmetry, and surface treatment on the resulting lattices of defects and explain their arrangements by application of topological rules. Last, we show the formation of detailed kaleidoscopic textures after the system is cooled down across the nematic-smectic A phase transition, frustrating the defects and surrounding structures with the equal-layer spacing condition of the smectic phase.
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Affiliation(s)
- Dae Seok Kim
- Graduate School of Nanoscience and Technology and KINC, KAIST, Daejeon 34141, Republic of Korea
- UMR Gulliver 7083 CNRS, ESPCI ParisTech, PSL Research University, 10 rue Vauquelin, 75005 Paris, France
| | - Simon Čopar
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
| | - Uroš Tkalec
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia
- Department of Condensed Matter Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology and KINC, KAIST, Daejeon 34141, Republic of Korea
- Department of Chemistry and KINC, KAIST, Daejeon 34141, Republic of Korea
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49
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Kasyanova IV, Gorkunov MV, Artemov VV, Geivandov AR, Mamonova AV, Palto SP. Liquid crystal metasurfaces on micropatterned polymer substrates. OPTICS EXPRESS 2018; 26:20258-20269. [PMID: 30119338 DOI: 10.1364/oe.26.020258] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Formation of photonic liquid crystal metasurfaces on rubbed polyimide substrates patterned by focused ion beam is demonstrated. Modulation of the surface anchoring conditions with periods from 1 to 6 micrometers gives rise to periodic deformation of the nematic liquid crystal director field. The exact periodicity is confirmed by the light diffraction measurements. Distinct colors originating from the specific zero-order diffraction spectra are observed and qualitatively explained in terms of an analytical model within the one-constant approximation. Quantitatively accurate optical spectra are obtained by the full scale numerical simulations taking into account all relevant material parameters. The results pave the way for hybrid liquid-crystal-based metasurfaces with tunable optical transmission, diffraction, and lasing.
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50
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Kowalski BA, Mostajeran C, Godman NP, Warner M, White TJ. Curvature by design and on demand in liquid crystal elastomers. Phys Rev E 2018; 97:012504. [PMID: 29448377 DOI: 10.1103/physreve.97.012504] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Indexed: 12/27/2022]
Abstract
The shape of liquid crystalline elastomers (LCEs) with spatial variation in the director orientation can be transformed by exposure to a stimulus. Here, informed by previously reported analytical treatments, we prepare complex spiral patterns imprinted into LCEs and quantify the resulting shape transformation. Quantification of the stimuli-induced shapes reveals good agreement between predicted and experimentally observed curvatures. We conclude this communication by reporting a design strategy to allow LCE films to be anchored at their external boundaries onto rigid substrates without incurring internal, mechanical-mismatch stresses upon actuation, a critical advance to the realization of shape transformation of LCEs in practical device applications.
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Affiliation(s)
- B A Kowalski
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA.,Azimuth Corporation, Beavercreek, Ohio 45431, USA
| | - C Mostajeran
- Department of Engineering, University of Cambridge CB2 1PZ, United Kingdom
| | - N P Godman
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - M Warner
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - T J White
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
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