1
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Abdelrahman MK, Wagner RJ, Kalairaj MS, Zadan M, Kim MH, Jang LK, Wang S, Javed M, Dana A, Singh KA, Hargett SE, Gaharwar AK, Majidi C, Vernerey FJ, Ware TH. Material assembly from collective action of shape-changing polymers. Nat Mater 2024; 23:281-289. [PMID: 38177377 DOI: 10.1038/s41563-023-01761-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 11/14/2023] [Indexed: 01/06/2024]
Abstract
Some animals form transient, responsive and solid-like ensembles through dynamic structural interactions. These ensembles demonstrate emergent responses such as spontaneous self-assembly, which are difficult to achieve in synthetic soft matter. Here we use shape-morphing units comprising responsive polymers to create solids that self-assemble, modulate their volume and disassemble on demand. The ensemble is composed of a responsive hydrogel, liquid crystal elastomer or semicrystalline polymer ribbons that reversibly bend or twist. The dispersions of these ribbons mechanically interlock, inducing reversible aggregation. The aggregated liquid crystal elastomer ribbons have a 12-fold increase in the yield stress compared with cooled dispersion and contract by 34% on heating. Ribbon type, concentration and shape dictate the aggregation and govern the global mechanical properties of the solid that forms. Coating liquid crystal elastomer ribbons with a liquid metal begets photoresponsive and electrically conductive aggregates, whereas seeding cells on hydrogel ribbons enables self-assembling three-dimensional scaffolds, providing a versatile platform for the design of dynamic materials.
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Affiliation(s)
- Mustafa K Abdelrahman
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Robert J Wagner
- Mechanical Engineering Department, Materials Science and Engineering Program, University of Colorado, Boulder, CO, USA
- Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | | | - Mason Zadan
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Min Hee Kim
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Lindy K Jang
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- Materials Engineering Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Suitu Wang
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Mahjabeen Javed
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Asaf Dana
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Kanwar Abhay Singh
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Sarah E Hargett
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Akhilesh K Gaharwar
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Franck J Vernerey
- Mechanical Engineering Department, Materials Science and Engineering Program, University of Colorado, Boulder, CO, USA
| | - Taylor H Ware
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA.
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA.
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2
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Wang S, Lim S, Tasmim S, Kalairaj MS, Rivera-Tarazona LK, Abdelrahman MK, Javed M, George SM, Lee YJ, Jawed MK, Ware TH. Reconfigurable Growth of Engineered Living Materials. Adv Mater 2024:e2309818. [PMID: 38288578 DOI: 10.1002/adma.202309818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/11/2024] [Indexed: 02/10/2024]
Abstract
The growth of multicellular organisms is a process akin to additive manufacturing where cellular proliferation and mechanical boundary conditions, among other factors, drive morphogenesis. Engineers have limited ability to engineer morphogenesis to manufacture goods or to reconfigure materials comprised of biomass. Herein, a method that uses biological processes to grow and regrow magnetic engineered living materials (mELMs) into desired geometries is reported. These composites contain Saccharomyces cerevisiae and magnetic particles within a hydrogel matrix. The reconfigurable manufacturing process relies on the growth of living cells, magnetic forces, and elastic recovery of the hydrogel. The mELM then adopts a form in an external magnetic field. Yeast within the material proliferates, resulting in 259 ± 14% volume expansion. Yeast proliferation fixes the magnetic deformation, even when the magnetic field is removed. The shape fixity can be up to 99.3 ± 0.3%. The grown mELM can recover up to 73.9 ± 1.9% of the original form by removing yeast cell walls. The directed growth and recovery process can be repeated at least five times. This work enables ELMs to be processed and reprocessed into user-defined geometries without external material deposition.
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Affiliation(s)
- Suitu Wang
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77840, USA
| | - Sangmin Lim
- Department of Mechanical & Aerospace Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Seelay Tasmim
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77840, USA
| | | | | | - Mustafa K Abdelrahman
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77840, USA
| | - Mahjabeen Javed
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77840, USA
| | - Sasha M George
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77840, USA
| | - Yoo Jin Lee
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77840, USA
| | - M Khalid Jawed
- Department of Mechanical & Aerospace Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Taylor H Ware
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77840, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77840, USA
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3
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Tabrizi M, Clement JA, Babaei M, Martinez A, Gao J, Ware TH, Shankar MR. Three-dimensional blueprinting of molecular patterns in liquid crystalline polymers. Soft Matter 2024; 20:511-522. [PMID: 38113054 DOI: 10.1039/d3sm01374j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Exploiting the interplay of anisotropic diamagnetic susceptibility of liquid crystalline monomers and site selective photopolymerization enables the fabrication of 3D freeforms with highly refined microstructures. Utilizing chain transfer agents in the mesogenic inks presents a pathway for broadly tuning the mechanical properties of liquid crystalline polymers and their response to stimuli. In particular, the combination of 1,4-benzenedimethanethiol and tetrabromomethane is shown to enable voxelated blueprinting of molecular order, while allowing for a modulation of the crosslink density and the mechanical properties. The formulation of these monomers allows for the resolution of the voxels to approach the limits set by the coherence lengths defined by the anchoring from surfaces. These compositions demonstrate the expected thermotropic responses while allowing for their functionalization with photochromic switches to elicit photomechanical responses. Actuation strains are shown to outstrip that accomplished with prior systems that did not access chain transfer agents to modulate the structure of the macromolecular network. Test cases of this system are shown to create freeform actuators that exploit the refined director patterns during high-resolution printing. These include topological defects, hierarchically-structured light responsive grippers, and biomimetic flyers whose flight dynamics can be actively modulated via irradiation with light.
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Affiliation(s)
- Mohsen Tabrizi
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - J Arul Clement
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Mahnoush Babaei
- Department of Aerospace Engineering & Engineering Mechanics, University of Texas at Austin, 2617 Wichita Street, C0600, Austin, TX 78712, USA.
| | - Angel Martinez
- Department of Applied Physics and Materials Science, Northern Arizona University, Science Annex, 525 S Beaver St, Flagstaff, AZ 86011, USA.
| | - Junfeng Gao
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, 101 Bizzell Street, College Station, TX 77843, USA
- Department of Materials Science and Engineering, Texas A&M University, 209 Reed McDonald Building, College Station, TX 77843, USA.
| | - M Ravi Shankar
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
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Lee YJ, Abdelrahman MK, Kalairaj MS, Ware TH. Self-Assembled Microactuators Using Chiral Liquid Crystal Elastomers. Small 2023; 19:e2302774. [PMID: 37291979 DOI: 10.1002/smll.202302774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/18/2023] [Indexed: 06/10/2023]
Abstract
Materials that undergo reversible changes in form typically require top-down processing to program the microstructure of the material. As a result, it is difficult to program microscale, 3D shape-morphing materials that undergo non-uniaxial deformations. Here, a simple bottom-up fabrication approach to prepare bending microactuators is described. Spontaneous self-assembly of liquid crystal (LC) monomers with controlled chirality within 3D micromold results in a change in molecular orientation across thickness of the microstructure. As a result, heating induces bending in these microactuators. The concentration of chiral dopant is varied to adjust the chirality of the monomer mixture. Liquid crystal elastomer (LCE) microactuators doped with 0.05 wt% of chiral dopant produce needle-shaped actuators that bend from flat to an angle of 27.2 ± 11.3° at 180 °C. Higher concentrations of chiral dopant lead to actuators with reduced bending, and lower concentrations of chiral dopant lead to actuators with poorly controlled bending. Asymmetric molecular alignment inside 3D structure is confirmed by sectioning actuators. Arrays of microactuators that all bend in the same direction can be fabricated if symmetry of geometry of the microstructure is broken. It is envisioned that the new platform to synthesize microstructures can further be applied in soft robotics and biomedical devices.
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Affiliation(s)
- Yoo Jin Lee
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Mustafa K Abdelrahman
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
| | | | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
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5
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Touchet-Valle E, Tasmim S, Ware TH, McDougall MP. Evaluation of Low-Loss Polymer Switches for Multinuclear MRI/S . Annu Int Conf IEEE Eng Med Biol Soc 2023; 2023:1-5. [PMID: 38083302 DOI: 10.1109/embc40787.2023.10340712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Implementation of multinuclear MRI/S as a diagnostic tool in clinical settings faces many challenges. One of those challenges is the development of highly sensitive multinuclear RF coils. Current multi-tuning techniques incorporate lossy components that impact the highest achievable SNR for at least one of the coil frequencies. As a result, optimization of multinuclear coil designs continues to be a priority for RF hardware engineers. To address this challenge, a new frequency switching technology that incorporates stimuli-responsive polymer materials was explored. Q measurements were used as a comparison metric between single-tuned, a standard switching network, and the proposed switching technology. The Q losses measured in the new switching method remained below 38% when compared to single-tuned coils. These results are consistent with low loss values reported using traditional switching networks. Furthermore, preliminary testing indicates that there is potential for improvement. These results establish the new technology as a promising alternative to traditional switching techniques.Clinical Relevance- A low loss multi-tuning technique for MRI radiofrequency coils has the potential of improving the study and diagnosis of disease.
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6
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Tasmim S, Yousuf Z, Rahman FS, Seelig E, Clevenger AJ, VandenHeuvel SN, Ambulo CP, Raghavan S, Zimmern PE, Romero-Ortega MI, Ware TH. Liquid crystal elastomer based dynamic device for urethral support: Potential treatment for stress urinary incontinence. Biomaterials 2023; 292:121912. [PMID: 36434829 PMCID: PMC9772118 DOI: 10.1016/j.biomaterials.2022.121912] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 11/11/2022] [Indexed: 11/20/2022]
Abstract
Stress urinary incontinence (SUI) is characterized by the involuntary loss of urine due to increased intra-abdominal pressure during coughing, sneezing, or exercising. SUI affects 20-40% of the female population and is exacerbated by aging. Severe SUI is commonly treated with surgical implantation of an autologous or a synthetic sling underneath the urethra for support. These slings, however, are static, and their tension cannot be non-invasively adjusted, if needed, after implantation. This study reports the fabrication of a novel device based on liquid crystal elastomers (LCEs) capable of changing shape in response to temperature increase induced by transcutaneous IR light. The shape change of the LCE-based device was characterized in a scar tissue phantom model. An in vitro urinary tract model was designed to study the efficacy of the LCE-based device to support continence and adjust sling tension with IR illumination. Finally, the device was acutely implanted and tested for induced tension changes in female multiparous New Zealand white rabbits. The LCE device achieved 5.6% ± 1.1% actuation when embedded in an agar gel with an elastic modulus of 100 kPa. The corresponding device temperature was 44.9 °C ± 0.4 °C, and the surrounding agar temperature stayed at 42.1 °C ± 0.4 °C. Leaking time in the in vitro urinary tract model significantly decreased (p < 0.0001) when an LCE-based cuff was sutured around the model urethra from 5.2min ± 1min to 2min ±0.5min when the cuff was illuminated with IR light. Normalized leak point force (LPF) increased significantly (p = 0.01) with the implantation of an LCE-CB cuff around the bladder neck of multiparous rabbits. It decreased significantly (p = 0.023) when the device was actuated via IR light illumination. These results demonstrate that LCE material could be used to fabricate a dynamic device for treating SUI in women.
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Affiliation(s)
- Seelay Tasmim
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Zuha Yousuf
- Departments of Bioengineering and Biomedical Science, University of Houston, Houston, TX, 77004, USA
| | - Farial S Rahman
- Departments of Bioengineering and Biomedical Science, University of Houston, Houston, TX, 77004, USA
| | - Emily Seelig
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Abigail J Clevenger
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Sabrina N VandenHeuvel
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Cedric P Ambulo
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Dayton, OH, 45433, USA
| | - Shreya Raghavan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Philippe E Zimmern
- Department of Urology, The University of Texas Southwestern, Dallas, TX, 75390, USA
| | - Mario I Romero-Ortega
- Departments of Bioengineering and Biomedical Science, University of Houston, Houston, TX, 77004, USA
| | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA.
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7
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Rivera-Tarazona LK, Sivaperuman Kalairaj M, Corazao T, Javed M, Zimmern PE, Subashchandrabose S, Ware TH. Controlling shape morphing and cell release in engineered living materials. Biomater Adv 2022; 143:213182. [PMID: 36375222 PMCID: PMC11005089 DOI: 10.1016/j.bioadv.2022.213182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 10/14/2022] [Accepted: 10/30/2022] [Indexed: 06/16/2023]
Abstract
Engineered living materials (ELMs) derive functionality from both a polymer matrix and the behavior of living cells within the material. The long-term goal of this work is to enable a system of ELM-based medical devices with both mechanical and bioactive functionality. Here, we fabricate multifunctional, stimuli-responsive ELMs comprised of acrylic hydrogel matrix and Escherichia coli. These ELMs undergo controlled changes in form and have a controlled release of bacteria from the composite. We hypothesize that the mechanical forces associated with cell proliferation within a covalently-crosslinked, non-degradable hydrogel are responsible for both phenomena. At constant cell loading, increased hydrogel elastic modulus significantly reduces both cell delivery and volume change associated with cell proliferation. ELMs that change volume over 100 % also result in ~106 colony forming units/mL in the growth medium over 2 h after 1 day of growth. At constant monomer feed ratios, increased cell loading leads to significantly increased cell delivery. Finally, these prokaryotic ELMs were investigated for their potential to deliver a probiotic that can reduce the proliferation of a uropathogen in vitro. Controlling the long-term delivery of bacteria could potentially be used in biomedical applications to modulate microbial communities within the human body.
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Affiliation(s)
| | | | - Tyler Corazao
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Mahjabeen Javed
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Philippe E Zimmern
- Department of Urology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sargurunathan Subashchandrabose
- Department of Veterinary Pathobiology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
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8
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Javed M, Corazao T, Saed MO, Ambulo CP, Li Y, Kessler MR, Ware TH. Programmable Shape Change in Semicrystalline Liquid Crystal Elastomers. ACS Appl Mater Interfaces 2022; 14:35087-35096. [PMID: 35866446 DOI: 10.1021/acsami.2c07533] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liquid crystal elastomers (LCEs) are stimuli-responsive materials capable of reversible and programmable shape change in response to an environmental stimulus. Despite the highly responsive nature of these materials, the modest elastic modulus and blocking stress exhibited by these actuating materials can be limiting in some engineering applications. Here, we engineer a semicrystalline LCE, where the incorporation of semicrystallinity in a lightly cross-linked liquid crystalline network yields tough and highly responsive materials. Directed self-assembly can be employed to program director profiles through the thickness of the semicrystalline LCE. In short, we use the alignment of a liquid crystal monomer phase to pattern the anisotropy of a semicrystalline polymer network. Both the semicrystalline-liquid crystalline and liquid crystalline-isotropic phase transition temperatures provide controllable shape transformations. A planarly aligned sample's normalized dimension parallel to the nematic director decreases from 1 at room temperature to 0.42 at 250 °C. The introduction of the semicrystalline nature also enhances the mechanical properties exhibited by the semicrystalline LCE. Semicrystalline LCEs have a storage modulus of 390 MPa at room temperature, and monodomain samples are capable of generating a contractile stress of 2.7 MPa on heating from 25 to 50 °C, far below the nematic to isotropic transition temperature. The robust mechanical properties of this material combined with the high actuation strain can be leveraged for applications such as soft robotics and actuators capable of doing significant work.
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Affiliation(s)
- Mahjabeen Javed
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Tyler Corazao
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
| | | | - Cedric P Ambulo
- Air Force Research Laboratory, Dayton, Ohio 45433, United States
| | - Yuzhan Li
- University of Science and Technology Beijing, Beijing 100083, China
| | - Michael R Kessler
- North Dakota State University, Fargo, North Dakota 58108, United States
| | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
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9
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Wang S, Rivera-Tarazona LK, Abdelrahman MK, Ware TH. Digitally Programmable Manufacturing of Living Materials Grown from Biowaste. ACS Appl Mater Interfaces 2022; 14:20062-20072. [PMID: 35442018 DOI: 10.1021/acsami.2c03109] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Material manufacturing strategies that use little energy, valorize waste, and result in degradable products are urgently needed. Strategies that transform abundant biomass into functional materials form one approach to these emerging manufacturing techniques. From a biological standpoint, morphogenesis of biological tissues is a "manufacturing" mode without energy-intensive processes, large carbon footprints, and toxic wastes. Inspired by biological morphogenesis, we propose a manufacturing strategy by embedding living Saccharomyces cerevisiae (Baker's yeast) within a synthetic acrylic hydrogel matrix. By culturing the living materials in media derived from bread waste, encapsulated yeast cells can proliferate, resulting in a dramatic dry mass and volume increase of the whole living material. After growth, the final material is up to 96 wt % biomass and 590% larger in volume than the initial object. By digitally programming the cell viability through UV irradiation or photodynamic inactivation, the living materials can form complex user-defined relief surfaces or 3D objects during growth. Ultimately, the grown structures can also be designed to be degradable. The proposed living material manufacturing strategy cultured from biowaste may pave the way for future ecologically friendly manufacturing of materials.
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Affiliation(s)
- Suitu Wang
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Laura K Rivera-Tarazona
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Mustafa K Abdelrahman
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Taylor H Ware
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
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10
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Duffy D, Javed M, Abdelrahman MK, Ware TH, Warner M, Biggins JS. Metric mechanics with nontrivial topology: Actuating irises, cylinders, and evertors. Phys Rev E 2021; 104:065004. [PMID: 35030939 DOI: 10.1103/physreve.104.065004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/22/2021] [Indexed: 11/07/2022]
Abstract
Liquid crystal elastomers contract along their director on heating and recover on cooling, offering great potential as actuators and artificial muscles. If a flat sheet is programed with a spatially varying director pattern, then it will actuate into a curved surface, allowing the material to act as a strong machine such as a grabber or lifter. Here we study the actuation of programed annular sheets which, owing to their central hole, can sidestep constraints on area and orientation. We systematically catalog the set of developable surfaces encodable via axisymmetric director patterns and uncover several qualitatively new modes of actuation, including cylinders, irises, and everted surfaces in which the inner boundary becomes the outer boundary after actuation. We confirm our designs with a combination of experiments and numerics. Many of our actuators can reattain their initial inner or outer radius upon completing actuation, making them particularly promising, as they can avoid potentially problematic stresses in their activated state even when fixed onto a frame or pipe.
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Affiliation(s)
- D Duffy
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - M Javed
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, USA.,Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - M K Abdelrahman
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, USA.,Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - T H Ware
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, USA.,Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, USA.,Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - M Warner
- Department of Physics, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - J S Biggins
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
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11
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Abstract
Shape-morphing polymers have gained particular attention due to their unique capability of shape transformation under numerous external stimuli such as light, pH, and temperature. Their shape-morphing properties can be used in various applications such as robotics, artificial muscles, and biomedical devices. To take advantage of the stimuli-responsive properties of the smart polymers in such applications, programming shape change precisely through a facile synthetic procedure is essential. Programmable shape-morphing is readily obtained in hydrogels and liquid crystal polymer networks, but shape programming of semicrystalline polymers usually relies on low-resolution mechanical deformation. In this paper, a semicrystalline shape-morphing polymer with a controlled shape programmability was developed via photopatterning crystal orientation using a spatially controlled photopolymerization technique. The semicrystalline polymer network forms aligned crystallites at the boundaries between dark and bright regions during photopolymerization using a projector, which introduces an anisotropic stimulus response in the films. The semicrystalline polymer films with photoaligned crystallites expand 9-15% in the direction perpendicular to the patterned lines when heated above the melting temperature. Furthermore, spatially patterning the crystal orientation enables the formation of various complex 3D structures including a helical coil, a coil with a handedness inversion, a cone, a saddle, and a twisting flower. Finally, the magnitude of the shape transformation was controlled by varying the polymerization temperatures, and the actuation temperature was tuned by changing the amount of crystallinity in the polymer films. The simplicity and ease of control of our approach to program complex 3D structures from 2D semicrystalline polymer films make it a promising system for the aforementioned applications.
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Affiliation(s)
- Lindy K Jang
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77840, United States
| | - Mustafa K Abdelrahman
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77840, United States
| | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77840, United States
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77840, United States
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12
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Kim H, Abdelrahman MK, Choi J, Kim H, Maeng J, Wang S, Javed M, Rivera-Tarazona LK, Lee H, Ko SH, Ware TH. From Chaos to Control: Programmable Crack Patterning with Molecular Order in Polymer Substrates. Adv Mater 2021; 33:e2008434. [PMID: 33860580 DOI: 10.1002/adma.202008434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/31/2021] [Indexed: 06/12/2023]
Abstract
Cracks are typically associated with the failure of materials. However, cracks can also be used to create periodic patterns on the surfaces of materials, as observed in the skin of crocodiles and elephants. In synthetic materials, surface patterns are critical to micro- and nanoscale fabrication processes. Here, a strategy is presented that enables freely programmable patterns of cracks on the surface of a polymer and then uses these cracks to pattern other materials. Cracks form during deposition of a thin film metal on a liquid crystal polymer network (LCN) and follow the spatially patterned molecular order of the polymer. These patterned sub-micrometer scale cracks have an order parameter of 0.98 ± 0.02 and form readily over centimeter-scale areas on the flexible substrates. The patterning of the LCN enables cracks that turn corners, spiral azimuthally, or radiate from a point. Conductive inks can be filled into these oriented cracks, resulting in flexible, anisotropic, and transparent conductors. This materials-based processing approach to patterning cracks enables unprecedented control of the orientation, length, width, and depth of the cracks without costly lithography methods. This approach promises new architectures of electronics, sensors, fluidics, optics, and other devices with micro- and nanoscale features.
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Affiliation(s)
- Hyun Kim
- Sensors and Electron Devices Directorate, CCDC Army Research Laboratory, Adelphi, MD, 20783, USA
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Mustafa K Abdelrahman
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Joonmyung Choi
- Department of Mechanical Design Engineering, Hanyang University, Seoul, 04763, Republic of Korea
- Department of Mechanical Engineering, BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, 15588, Republic of Korea
| | - Hongdeok Kim
- Department of Mechanical Design Engineering, Hanyang University, Seoul, 04763, Republic of Korea
- Department of Mechanical Engineering, BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, 15588, Republic of Korea
| | - Jimin Maeng
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Suitu Wang
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Mahjabeen Javed
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Laura K Rivera-Tarazona
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Habeom Lee
- School of Mechanical Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Seung Hwan Ko
- Department of Mechanical Engineering, Seoul National University, Seoul, 08826, Republic of Korea
- Institute of Advanced Machines and Design (IAMD) / Institute of Engineering Research, Seoul National University, Seoul, 08826, Republic of Korea
| | - Taylor H Ware
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
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13
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Wang S, Maruri DP, Boothby JM, Lu X, Rivera-Tarazona LK, Varner VD, Ware TH. Anisotropic, porous hydrogels templated by lyotropic chromonic liquid crystals. J Mater Chem B 2021; 8:6988-6998. [PMID: 32626869 DOI: 10.1039/d0tb00904k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Approaches to control the microstructure of hydrogels enable the control of cell-material interactions and the design of stimuli-responsive materials. We report a versatile approach for the synthesis of anisotropic polyacrylamide hydrogels using lyotropic chromonic liquid crystal (LCLC) templating. The orientational order of LCLCs in a mold can be patterned by controlling surface anchoring conditions, which in turn patterns the polymer network. The resulting hydrogels have tunable pore size and mechanical anisotropy. For example, the elastic moduli measured parallel and perpendicular to the LCLC order are 124.9 ± 6.4 kPa and 17.4 ± 1.1 kPa for a single composition. The resulting anisotropic hydrogels also have 30% larger swelling normal to the LCLC orientation than along the LCLC orientation. By patterning the LCLC order, this anisotropic swelling can be used to create 3D hydrogel structures. These anisotropic gels can also be functionalized with extracellular matrix (ECM) proteins and used as compliant substrata for cell culture. As an illustrative example, we show that the patterned hydrogel microstructure can be used to direct the orientation of cultured human corneal fibroblasts. This strategy to make anisotropic hydrogels has potential for enabling patternable tissue scaffolds, soft robotics, or microfluidic devices.
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Affiliation(s)
- Suitu Wang
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas, USA.
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14
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Ambulo CP, Ford MJ, Searles K, Majidi C, Ware TH. 4D-Printable Liquid Metal-Liquid Crystal Elastomer Composites. ACS Appl Mater Interfaces 2021; 13:12805-12813. [PMID: 33356119 DOI: 10.1021/acsami.0c19051] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Soft actuators that undergo programmable shape change in response to a stimulus are enabling components of future soft robots and other soft machines. Strategies to power these actuators often require the incorporation of rigid, electrically conductive materials into the soft actuator, thus limiting the compliance and shape change of the material. In this study, we develop a 4D-printable composite composed of liquid crystal elastomer (LCE) matrix with dispersed droplets of eutectic gallium indium alloy (EGaIn). Using deformable EGaIn droplets in place of rigid conductive fillers preserves the compliance and shape-morphing properties of the LCE. The process enables 4D-printed LCE actuators capable of photothermal and electrothermal actuation. At low liquid metal (LM) concentrations (71 wt %), the composite actuator exhibits a photothermal response upon irradiation of near-IR light. Printed actuators with a twisted nematic configuration are capable of bending angles of 150° at 800 mW cm-2. At higher LM concentrations (88 wt %), the embedded LM droplets can form percolating networks that conduct electricity and enable electrical Joule heating of the LCE. Actuation strain ranging from 5 to 12% is controlled by the amount of electrical power that is delivered to the composite. We also introduce a method for multimaterial printing of monolithic structures where the LM filler loading is spatially varied. These multifunctional materials exhibit innate responsivity where the actuator behaves as an electrical switch and can report one of two states (on/off). These multiresponsive, 4D-printable composites enable multifunctional, mechanically active structures that can be powered with IR light or low DC voltages.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Michael J Ford
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kyle Searles
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
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15
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Abstract
Stimuli-responsive materials are able to undergo controllable changes in materials properties in response to external cues. Increasing efforts have been directed towards building materials that mimic the responsive nature of biological systems. Nevertheless, limitations remain surrounding the way these synthetic materials interact and respond to their environment. In particular, it is difficult to synthesize synthetic materials that respond with specificity to poorly differentiated (bio)chemical and weak physical stimuli. The emerging area of engineered living materials (ELMs) includes composites that combine living cells and synthetic materials. ELMs have yielded promising advances in the creation of stimuli-responsive materials that respond with diverse outputs in response to a broad array of biochemical and physical stimuli. This review describes advances made in the genetic engineering of the living component and the processing-property relationships of stimuli-responsive ELMs. Finally, the implementation of stimuli-responsive ELMs as environmental sensors, biomedical sensors, drug delivery vehicles, and soft robots is discussed.
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Affiliation(s)
- Laura K Rivera-Tarazona
- Department of Biomedical Engineering, Texas A&M University, 101 Bizzell Street, College Station, TX 77843, USA.
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16
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Rihani R, Tasnim N, Javed M, Usoro JO, D'Souza TM, Ware TH, Pancrazio JJ. Liquid Crystalline Polymers: Opportunities to Shape Neural Interfaces. Neuromodulation 2021; 25:1259-1267. [PMID: 33501705 DOI: 10.1111/ner.13364] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 12/21/2020] [Accepted: 01/05/2021] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Polymers have emerged as constituent materials for the creation of microscale neural interfaces; however, limitations regarding water permeability, delamination, and material degradation impact polymeric device robustness. Liquid crystal polymers (LCPs) have molecular order like a solid but with the fluidity of a liquid, resulting in a unique material, with properties including low water permeability, chemical inertness, and mechanical toughness. The objective of this article is to review the state-of-the-art regarding the use of LCPs in neural interface applications and discuss challenges and opportunities where this class of materials can advance the field of neural interfaces. MATERIALS AND METHODS This review article focuses on studies that leverage LCP materials to interface with the nervous system in vivo. A comprehensive literature search was performed using PubMed, Web of Science (Clarivate Analytics), and Google Scholar. RESULTS There have been recent efforts to create neural interfaces that leverage the material advantages of LCPs. The literature offers examples of LCP as a basis for implantable medical devices and neural interfaces in the form of planar electrode arrays for retinal prosthetic, electrocorticography applications, and cuff-like structures for interfacing the peripheral nerve. In addition, there have been efforts to create penetrating intracortical devices capable of microstimulation and resolution of biopotentials. Recent work with a subclass of LCPs, namely liquid crystal elastomers, demonstrates that it is possible to create devices with features that deploy away from a central implantation site to interface with a volume of tissue while offering the possibility of minimizing tissue damage. CONCLUSION We envision the creation of novel microscale neural interfaces that leverage the physical properties of LCPs and have the capability of deploying within neural tissue for enhanced integration and performance.
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Affiliation(s)
- Rashed Rihani
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Nishat Tasnim
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Mahjabeen Javed
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA.,Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Joshua O Usoro
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Tania M D'Souza
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA.,Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA.,Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
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17
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Affiliation(s)
- Xili Lu
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
- Current address: State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
| | - Cedric P. Ambulo
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
| | - Suitu Wang
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
- Current address: Department of Materials Science and Engineering Texas A&M University College Station TX 77843 USA
| | - Laura K. Rivera‐Tarazona
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
- Current address: Department of Biomedical Engineering Texas A&M University College Station TX 77843 USA
| | - Hyun Kim
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
- Current address: Sensors and Electron Devices Directorate CCDC Army Research Laboratory Adelphi MD 20783 USA
| | - Kyle Searles
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
| | - Taylor H. Ware
- Department of Bioengineering University of Texas at Dallas Richardson TX 75080 USA
- Current address: Department of Biomedical Engineering Texas A&M University College Station TX 77843 USA
- Current address: Department of Materials Science and Engineering Texas A&M University College Station TX 77843 USA
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18
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Lu X, Ambulo CP, Wang S, Rivera-Tarazona LK, Kim H, Searles K, Ware TH. 4D-Printing of Photoswitchable Actuators. Angew Chem Int Ed Engl 2021; 60:5536-5543. [PMID: 33217118 DOI: 10.1002/anie.202012618] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/02/2020] [Indexed: 12/15/2022]
Abstract
Shape-switching behavior, where a transient stimulus induces an indefinitely stable deformation that can be recovered on exposure to another transient stimulus, is critical to building smart structures from responsive polymers as continue power is not needed to maintain deformations. Herein, we 4D-print shape-switching liquid crystalline elastomers (LCEs) functionalized with supramolecular crosslinks, dynamic covalent crosslinks, and azobenzene. The salient property of shape-switching LCEs is that light induces long-lived, deformation that can be recovered on-demand by heating. UV-light isomerizes azobenzene from trans to cis, and temporarily breaks the supramolecular crosslinks, resulting in a programmed deformation. After UV, the shape-switching LCEs fix more than 90 % of the deformation over 3 days by the reformed supramolecular crosslinks. Using the shape-switching properties, we print Braille-like actuators that can be photoswitched to display different letters. This new class of photoswitchable actuators may impact applications such as deployable devices where continuous application of power is impractical.
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Affiliation(s)
- Xili Lu
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA.,Current address: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
| | - Cedric P Ambulo
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Suitu Wang
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA.,Current address: Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Laura K Rivera-Tarazona
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA.,Current address: Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Hyun Kim
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA.,Current address: Sensors and Electron Devices Directorate, CCDC Army Research Laboratory, Adelphi, MD, 20783, USA
| | - Kyle Searles
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Taylor H Ware
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA.,Current address: Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA.,Current address: Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
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19
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Bunton CM, Bassampour ZM, Boothby JM, Smith AN, Rose JV, Nguyen DM, Ware TH, Csaky KG, Lippert AR, Tsarevsky NV, Son DY. Degradable Silyl Ether–Containing Networks from Trifunctional Thiols and Acrylates. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Caleb M. Bunton
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Zahra M. Bassampour
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Jennifer M. Boothby
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Ashanti N. Smith
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Joseph V. Rose
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Daphne M. Nguyen
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Taylor H. Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Karl G. Csaky
- Retina Foundation of the Southwest, Dallas, Texas 75231, United States
| | - Alexander R. Lippert
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Nicolay V. Tsarevsky
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - David Y. Son
- Department of Chemistry, Center for Drug Discovery, Design and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
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20
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Ambulo CP, Tasmim S, Wang S, Abdelrahman MK, Zimmern PE, Ware TH. Processing advances in liquid crystal elastomers provide a path to biomedical applications. J Appl Phys 2020; 128:140901. [PMID: 33060862 PMCID: PMC7546753 DOI: 10.1063/5.0021143] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/24/2020] [Indexed: 05/08/2023]
Abstract
Liquid crystal elastomers (LCEs) are a class of stimuli-responsive polymers that undergo reversible shape-change in response to environmental changes. The shape change of LCEs can be programmed during processing by orienting the liquid crystal phase prior to crosslinking. The suite of processing techniques that has been developed has resulted in a myriad of LCEs with different shape-changing behavior and mechanical properties. Aligning LCEs via mechanical straining yields large uniaxial actuators capable of a moderate force output. Magnetic fields are utilized to control the alignment within LCE microstructures. The generation of out-of-plane deformations such as bending, twisting, and coning is enabled by surface alignment techniques within thin films. 4D printing processes have emerged that enable the fabrication of centimeter-scale, 3D LCE structures with a complex alignment. The processing technique also determines, to a large extent, the potential applications of the LCE. For example, 4D printing enables the fabrication of LCE actuators capable of replicating the forces generated by human muscles. Employing surface alignment techniques, LCE films can be designed for use as coatings or as substrates for stretchable electronics. The growth of new processes and strategies opens and strengthens the path for LCEs to be applicable within biomedical device designs.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | | | | | | | - Philippe E Zimmern
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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21
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Ford MJ, Palaniswamy M, Ambulo CP, Ware TH, Majidi C. Size of liquid metal particles influences actuation properties of a liquid crystal elastomer composite. Soft Matter 2020; 16:5878-5885. [PMID: 32412038 DOI: 10.1039/d0sm00278j] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Composites of liquid crystal elastomer (LCE) that are electrically conductive have the potential to function as soft "artificial muscle" actuators that can be reversibly stimulated with electrical Joule-heating. Conductivity can be achieved by embedding the LCE with droplets of an alloy of gallium and indium that is liquid at room temperature. These soft artificial muscles are capable of >50% reversible actuation with an applied load. The key to actuation at high loadings of liquid metal (LM) is that the droplets deform with the surrounding matrix. By controlling the size of LM droplets through simple processing techniques, we show that the actuator properties of the LM-LCE muscle can be tuned. For example, composites with smaller liquid metal particles (ca. 10 μm or less) are stiffer than those with larger liquid metal particles (ca. >100 μm) and are capable of greater force output. However, smaller particles reduce actuation strain and composites with large particles exhibit significantly greater stroke length. Such tunability in actuation properties permits the fabrication of specialized soft artificial muscles, where processing of the composite controls actuation strain and actuation force.
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Affiliation(s)
- Michael J Ford
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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22
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Mu J, Jung de Andrade M, Fang S, Wang X, Gao E, Li N, Kim SH, Wang H, Hou C, Zhang Q, Zhu M, Qian D, Lu H, Kongahage D, Talebian S, Foroughi J, Spinks G, Kim H, Ware TH, Sim HJ, Lee DY, Jang Y, Kim SJ, Baughman RH. Sheath-run artificial muscles. Science 2020; 365:150-155. [PMID: 31296765 DOI: 10.1126/science.aaw2403] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 06/11/2019] [Indexed: 11/02/2022]
Abstract
Although guest-filled carbon nanotube yarns provide record performance as torsional and tensile artificial muscles, they are expensive, and only part of the muscle effectively contributes to actuation. We describe a muscle type that provides higher performance, in which the guest that drives actuation is a sheath on a twisted or coiled core that can be an inexpensive yarn. This change from guest-filled to sheath-run artificial muscles increases the maximum work capacity by factors of 1.70 to 2.15 for tensile muscles driven electrothermally or by vapor absorption. A sheath-run electrochemical muscle generates 1.98 watts per gram of average contractile power-40 times that for human muscle and 9.0 times that of the highest power alternative electrochemical muscle. Theory predicts the observed performance advantages of sheath-run muscles.
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Affiliation(s)
- Jiuke Mu
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Mônica Jung de Andrade
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Shaoli Fang
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Xuemin Wang
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA.,Department of Mechanical Engineering, Georgia Southern University, Statesboro, GA 30458, USA
| | - Enlai Gao
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA.,Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, Hubei 430072, China
| | - Na Li
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA.,Materials Science, MilliporeSigma, Milwaukee, WI 53209, USA
| | - Shi Hyeong Kim
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Hongzhi Wang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Chengyi Hou
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Qinghong Zhang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Meifang Zhu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Dong Qian
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Hongbing Lu
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Dharshika Kongahage
- Intelligent Polymer Research Institute, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Sepehr Talebian
- Intelligent Polymer Research Institute, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Javad Foroughi
- Intelligent Polymer Research Institute, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Geoffrey Spinks
- Intelligent Polymer Research Institute, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Hyun Kim
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Hyeon Jun Sim
- Center for Self-Powered Actuation, Department of Biomedical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Dong Yeop Lee
- Center for Self-Powered Actuation, Department of Biomedical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Yongwoo Jang
- Center for Self-Powered Actuation, Department of Biomedical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Seon Jeong Kim
- Center for Self-Powered Actuation, Department of Biomedical Engineering, Hanyang University, Seoul 04763, South Korea
| | - Ray H Baughman
- Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA.
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23
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Affiliation(s)
- Mustafa K. Abdelrahman
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Hyun Kim
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Jimin Maeng
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Patrick Ondrusek
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Taylor H. Ware
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
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24
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Maeng J, Rihani RT, Javed M, Rajput JS, Kim H, Bouton IG, Criss TA, Pancrazio JJ, Black BJ, Ware TH. Liquid crystal elastomers as substrates for 3D, robust, implantable electronics. J Mater Chem B 2020; 8:6286-6295. [DOI: 10.1039/d0tb00471e] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Liquid crystal elastomers are used as substrates for robust, implantable electronics that are planar processed then morph into 3D shapes.
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Affiliation(s)
- Jimin Maeng
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | - Rashed T. Rihani
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | - Mahjabeen Javed
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | - Jai Singh Rajput
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | - Hyun Kim
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | | | | | | | - Bryan J. Black
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | - Taylor H. Ware
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
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25
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Ford MJ, Ambulo CP, Kent TA, Markvicka EJ, Pan C, Malen J, Ware TH, Majidi C. A multifunctional shape-morphing elastomer with liquid metal inclusions. Proc Natl Acad Sci U S A 2019; 116:21438-21444. [PMID: 31591232 PMCID: PMC6815160 DOI: 10.1073/pnas.1911021116] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Natural soft tissue achieves a rich variety of functionality through a hierarchy of molecular, microscale, and mesoscale structures and ordering. Inspired by such architectures, we introduce a soft, multifunctional composite capable of a unique combination of sensing, mechanically robust electronic connectivity, and active shape morphing. The material is composed of a compliant and deformable liquid crystal elastomer (LCE) matrix that can achieve macroscopic shape change through a liquid crystal phase transition. The matrix is dispersed with liquid metal (LM) microparticles that are used to tailor the thermal and electrical conductivity of the LCE without detrimentally altering its mechanical or shape-morphing properties. Demonstrations of this composite for sensing, actuation, circuitry, and soft robot locomotion suggest the potential for versatile, tissue-like multifunctionality.
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Affiliation(s)
- Michael J Ford
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Cedric P Ambulo
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080
| | - Teresa A Kent
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Eric J Markvicka
- Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588
| | - Chengfeng Pan
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Jonathan Malen
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Taylor H Ware
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213;
- Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
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26
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Abstract
The ability to pattern material response, voxel by voxel, to direct actuation and manipulation in macroscopic structures can enable devices that utilize ambient stimuli to produce functional responses at length scales ranging from the micro- to the macroscopic. Fabricating liquid crystalline polymers (LCPs), where the molecular director is indexably defined in three-dimensional (3D) freeforms, can be a key enabler. Here, the combination of anisotropic magnetic susceptibility of the liquid crystalline monomers in a reorientable magnetic field and spatially selective photopolymerization using a digital micromirror device to independently define molecular orientation in light and/or heat-responsive multimaterial elements, which are additively incorporated into 3D freeforms, is exploited. This is shown to enable structural complexity across length scales in nontrivial geometries, including re-entrant shapes, which are responsive to either heat or light. A range of monomer compositions are optimized to include photoinitiators, light absorbers, and polymerization inhibitors to modulate the polymerization characteristics while simultaneously retaining the tailorability of the nematic alignment. The versatility of this framework is illustrated in an array of examples, including (i) thermomechanical generation of Gaussian-curved structures from flat geometries, (ii) light-responsive freeform topographies, and (iii) multiresponsive manipulators, which can be powered along independent axes using heat and/or light. The ability to integrate responses to multiple stimuli, where the principal directions of the mechanical output are arbitrarily tailored in a 3D freeform, enables new design spaces in soft robotics, micromechanical/fluidic systems, and optomechanical systems.
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Affiliation(s)
- Mohsen Tabrizi
- Department of Industrial Engineering, Swanson School of Engineering , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
| | - Taylor H Ware
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - M Ravi Shankar
- Department of Industrial Engineering, Swanson School of Engineering , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
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27
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Abstract
Hydrogels which morph between programmed shapes in response to aqueous stimuli are of significant interest for biosensors and artificial muscles, among other applications. However, programming hydrogel shape change at small size scales is a significant challenge. Here we use the inherent ordering capabilities of liquid crystals to create a mechanically anisotropic hydrogel; when coupled with responsive comonomers, the mechanical anisotropy in the network guides shape change in response to the desired aqueous condition. Our synthetic strategy hinges on the use of a methacrylic chromonic liquid crystal monomer which can be combined with a non-polymerizable chromonic of similar structure to vary the magnitude of shape change while retaining liquid crystalline order. This shape change is directional due to the mechanical anisotropy of the gel, which is up to 50% stiffer along the chromonic stack direction than perpendicular. Additionally, we show that the type of stimulus to which these anisotropic gels respond can be switched by incorporating responsive, hydrophilic comonomers without destroying the nematic phase or alignment. The utility of these properties is demonstrated in polymerized microstructures which exhibit Gaussian curvature in response to high pH due to emergent ordering in a micron-sized capillary.
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Affiliation(s)
- Jennifer M Boothby
- The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA.
| | - Jeremy Samuel
- The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA.
| | - Taylor H Ware
- The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA.
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28
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Kim H, Gibson J, Maeng J, Saed MO, Pimentel K, Rihani RT, Pancrazio JJ, Georgakopoulos SV, Ware TH. Responsive, 3D Electronics Enabled by Liquid Crystal Elastomer Substrates. ACS Appl Mater Interfaces 2019; 11:19506-19513. [PMID: 31070344 DOI: 10.1021/acsami.9b04189] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Traditional electronic devices are rigid, planar, and mechanically static. The combination of traditional electronic materials and responsive polymer substrates is of significant interest to provide opportunities to replace conventional electronic devices with stretchable, 3D, and responsive electronics. Liquid crystal elastomers (LCEs) are well suited to function as such dynamic substrates because of their large strain, reversible stimulus response that can be controlled through directed self-assembly of molecular order. Here, we discuss using LCEs as substrates for electronic devices that are flat during processing but then morph into controlled 3D structures. We design and demonstrate processes for a variety of electronic devices on LCEs including deformation-tolerant conducting traces and capacitors and cold temperature-responsive antennas. For example, patterning twisted nematic orientation within the substrate can be used to create helical electronic devices that stretch up to 100% with less than 2% change in resistance or capacitance. Moreover, we discuss self-morphing LCE antennas which can dynamically change the operating frequency from 2.7 GHz (room temperature) to 3.3 GHz (-65 °C). We envision applications for these 3D, responsive devices in wearable or implantable electronics and in cold-chain monitoring radio frequency identification sensors.
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Affiliation(s)
- Hyun Kim
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - John Gibson
- Department of Electrical and Computer Engineering , Florida International University , Miami , Florida 33174 , United States
| | - Jimin Maeng
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Mohand O Saed
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Krystine Pimentel
- Department of Electrical and Computer Engineering , Florida International University , Miami , Florida 33174 , United States
| | - Rashed T Rihani
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Joseph J Pancrazio
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Stavros V Georgakopoulos
- Department of Electrical and Computer Engineering , Florida International University , Miami , Florida 33174 , United States
| | - Taylor H Ware
- Department of Bioengineering , The University of Texas at Dallas , Richardson , Texas 75080 , United States
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29
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Rihani RT, Kim H, Black BJ, Atmaramani R, Saed MO, Pancrazio JJ, Ware TH. Liquid Crystal Elastomer-Based Microelectrode Array for In Vitro Neuronal Recordings. Micromachines (Basel) 2018; 9:E416. [PMID: 30424349 PMCID: PMC6211140 DOI: 10.3390/mi9080416] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/16/2018] [Indexed: 12/11/2022]
Abstract
Polymer-based biomedical electronics provide a tunable platform to interact with nervous tissue both in vitro and in vivo. Ultimately, the ability to control functional properties of neural interfaces may provide important advantages to study the nervous system or to restore function in patients with neurodegenerative disorders. Liquid crystal elastomers (LCEs) are a class of smart materials that reversibly change shape when exposed to a variety of stimuli. Our interest in LCEs is based on leveraging this shape change to deploy electrode sites beyond the tissue regions exhibiting inflammation associated with chronic implantation. As a first step, we demonstrate that LCEs are cellular compatible materials that can be used as substrates for fabricating microelectrode arrays (MEAs) capable of recording single unit activity in vitro. Extracts from LCEs are non-cytotoxic (>70% normalized percent viability), as determined in accordance to ISO protocol 10993-5 using fibroblasts and primary murine cortical neurons. LCEs are also not functionally neurotoxic as determined by exposing cortical neurons cultured on conventional microelectrode arrays to LCE extract for 48 h. Microelectrode arrays fabricated on LCEs are stable, as determined by electrochemical impedance spectroscopy. Examination of the impedance and phase at 1 kHz, a frequency associated with single unit recording, showed results well within range of electrophysiological recordings over 30 days of monitoring in phosphate-buffered saline (PBS). Moreover, the LCE arrays are shown to support viable cortical neuronal cultures over 27 days in vitro and to enable recording of prominent extracellular biopotentials comparable to those achieved with conventional commercially-available microelectrode arrays.
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Affiliation(s)
- Rashed T Rihani
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Hyun Kim
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Bryan J Black
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Rahul Atmaramani
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Mohand O Saed
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Joseph J Pancrazio
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Taylor H Ware
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
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Ambulo CP, Burroughs JJ, Boothby JM, Kim H, Shankar MR, Ware TH. Four-dimensional Printing of Liquid Crystal Elastomers. ACS Appl Mater Interfaces 2017; 9:37332-37339. [PMID: 28967260 DOI: 10.1021/acsami.7b11851] [Citation(s) in RCA: 190] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Three-dimensional structures capable of reversible changes in shape, i.e., four-dimensional-printed structures, may enable new generations of soft robotics, implantable medical devices, and consumer products. Here, thermally responsive liquid crystal elastomers (LCEs) are direct-write printed into 3D structures with a controlled molecular order. Molecular order is locally programmed by controlling the print path used to build the 3D object, and this order controls the stimulus response. Each aligned LCE filament undergoes 40% reversible contraction along the print direction on heating. By printing objects with controlled geometry and stimulus response, magnified shape transformations, for example, volumetric contractions or rapid, repetitive snap-through transitions, are realized.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Julia J Burroughs
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Jennifer M Boothby
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Hyun Kim
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - M Ravi Shankar
- Department of Industrial Engineering, The University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
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31
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Abstract
Materials that change shape are attractive candidates to replace traditional actuators for applications with power or size restrictions. In this work, we design a polymeric bilayer that changes shape in response to both heat and water by the incorporation of a water-responsive hydrophilic polymer with a heat-responsive liquid crystal elastomer. The distinct shape changes based on stimulus are controlled by the molecular order, and consequently the anisotropic modulus, of a liquid crystal elastomer. In response to water, the hydrophilic polymer layer expands, bending the bilayer along the path dictated by the anisotropic modulus of the liquid crystal elastomer layer, which is approximately 5 times higher along the molecular orientation than in perpendicular directions. We demonstrate that by varying the direction of this stiffer axis in LCE films, helical pitch of the swollen bilayer can be controlled from 0.1 to 20 mm. By spatially patterning the stiffer axis with a resolution of 900 μm2, we demonstrate bilayers that fold and bend based on the pattern within the LCE. In response to heat, the liquid crystal elastomer contracts along the direction of molecular order, and when this actuation is constrained by the hydrophilic polymer, this contraction results in a 3D shape that is distinct from the shape seen in water. Furthermore, by using the vitrification of the dry hydrophilic polymer this 3D shape can be retained in the bilayer after cooling. By utilizing sequential exposure to heat and water, we can drive the initially flat bilayer to reversibly shift between 3D shapes.
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Affiliation(s)
- J M Boothby
- Bioengineering Department, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX 75080, USA.
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32
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Affiliation(s)
- Hyun Kim
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080, United States
| | - Jennifer M. Boothby
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080, United States
| | - Sarvesh Ramachandran
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080, United States
| | - Cameron D. Lee
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080, United States
| | - Taylor H. Ware
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080, United States
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33
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Affiliation(s)
- Ruvini S. Kularatne
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
| | - Hyun Kim
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
| | - Jennifer M. Boothby
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
| | - Taylor H. Ware
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
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34
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Lee KM, Ware TH, Tondiglia VP, McBride MK, Zhang X, Bowman CN, White TJ. Initiatorless Photopolymerization of Liquid Crystal Monomers. ACS Appl Mater Interfaces 2016; 8:28040-28046. [PMID: 27636826 DOI: 10.1021/acsami.6b09144] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Liquid crystal monomers are widely employed in industry to prepare optical compensating films as well as extend or enhance the properties of certain display modes. Because of the thermotropic nature of liquid crystalline materials, polymerization of liquid crystalline monomers (sometimes referred to as reactive mesogens) is often initiated by radical photoinitiation (photopolymerization) of (meth)acrylate functional groups. Here, we report on the initiatorless photopolymerization of commercially available liquid crystalline monomers upon exposure to 365 nm UV light. Initiatorless polymerization is employed to prepare thin films as well as polymer stabilizing networks in mixtures with low-molar-mass liquid crystals. EPR and FTIR confirm radical generation upon exposure to 365 nm light and conversion of the acrylate functional groups. A potential mechanism is proposed, informed by control experiments that indicate that the monomers undergo a type II Norrish mechanism. The initiatorless polymerization of the liquid crystalline monomers yield liquid crystalline polymer networks with mechanical properties that can be equal to those prepared with conventional radical photoinitiators. We demonstrate that initiatorless polymerization of display modes significantly increases the voltage holding ratio, which could result in a reduction in drive voltages in flat-panel televisions and hand-held devices, extending battery life and reducing power consumption.
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Affiliation(s)
- Kyung Min Lee
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7750, United States
- Azimuth Corporation, 4027 Colonel Glenn Hwy, Beavercreek, Ohio 45431, United States
| | - Taylor H Ware
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7750, United States
- Azimuth Corporation, 4027 Colonel Glenn Hwy, Beavercreek, Ohio 45431, United States
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Vincent P Tondiglia
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7750, United States
- Azimuth Corporation, 4027 Colonel Glenn Hwy, Beavercreek, Ohio 45431, United States
| | - Matthew K McBride
- Chemical and Biological Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Xinpeng Zhang
- Chemical and Biological Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Christopher N Bowman
- Chemical and Biological Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Timothy J White
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7750, United States
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35
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Mostajeran C, Warner M, Ware TH, White TJ. Encoding Gaussian curvature in glassy and elastomeric liquid crystal solids. Proc Math Phys Eng Sci 2016; 472:20160112. [PMID: 27279777 PMCID: PMC4893188 DOI: 10.1098/rspa.2016.0112] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/05/2016] [Indexed: 11/22/2022] Open
Abstract
We describe shape transitions of thin, solid nematic sheets with smooth, preprogrammed, in-plane director fields patterned across the surface causing spatially inhomogeneous local deformations. A metric description of the local deformations is used to study the intrinsic geometry of the resulting surfaces upon exposure to stimuli such as light and heat. We highlight specific patterns that encode constant Gaussian curvature of prescribed sign and magnitude. We present the first experimental results for such programmed solids, and they qualitatively support theory for both positive and negative Gaussian curvature morphing from flat sheets on stimulation by light or heat. We review logarithmic spiral patterns that generate cone/anti-cone surfaces, and introduce spiral director fields that encode non-localized positive and negative Gaussian curvature on punctured discs, including spherical caps and spherical spindles. Conditions are derived where these cap-like, photomechanically responsive regions can be anchored in inert substrates by designing solutions that ensure compatibility with the geometric constraints imposed by the surrounding media. This integration of such materials is a precondition for their exploitation in new devices. Finally, we consider the radial extension of such director fields to larger sheets using nematic textures defined on annular domains.
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Affiliation(s)
- Cyrus Mostajeran
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - Mark Warner
- Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Taylor H. Ware
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433, USA
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Road, Richardson, TX 75080, USA
| | - Timothy J. White
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433, USA
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36
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Reit R, Zamorano D, Parker S, Simon D, Lund B, Voit W, Ware TH. Hydrolytically Stable Thiol-ene Networks for Flexible Bioelectronics. ACS Appl Mater Interfaces 2015; 7:28673-28681. [PMID: 26650346 DOI: 10.1021/acsami.5b10593] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Hydrolytically stable, tunable modulus polymer networks are demonstrated to survive harsh alkaline environments and offer promise for use in long-term implantable bioelectronic medicines known as electroceuticals. Today's polymer networks (such as polyimides or polysiloxanes) succeed in providing either stiff or soft substrates for bioelectronics devices; however, the capability to significantly tune the modulus of such materials is lacking. Within the space of materials with easily modified elastic moduli, thiol-ene copolymers are a subset of materials that offer a promising solution to build next generation flexible bioelectronics but have typically been susceptible to hydrolytic degradation chronically. In this inquiry, we demonstrate a materials space capable of tuning the substrate modulus and explore the mechanical behavior of such networks. Furthermore, we fabricate an array of microelectrodes that can withstand accelerated aging environments shown to destroy conventional flexible bioelectronics.
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Affiliation(s)
- Radu Reit
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
| | - Daniel Zamorano
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
| | - Shelbi Parker
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
| | - Dustin Simon
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
| | - Benjamin Lund
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
| | - Walter Voit
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
| | - Taylor H Ware
- Department of Bioengineering, ‡Department of Chemistry, §Department of Materials Science and Engineering, and ∥Department of Mechanical Engineering, The University of Texas at Dallas , 800 West Campbell Road, Mailstop RL 10, Richardson, Texas 75080, United States
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37
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Fuchi K, Ware TH, Buskohl PR, Reich GW, Vaia RA, White TJ, Joo JJ. Topology optimization for the design of folding liquid crystal elastomer actuators. Soft Matter 2015; 11:7288-7295. [PMID: 26270868 DOI: 10.1039/c5sm01671a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Aligned liquid crystal elastomers (LCEs) are capable of undergoing large reversible shape change in response to thermal stimuli and may act as actuators for many potential applications such as self-assembly and deployment of micro devices. Recent advances in LCE patterning tools have demonstrated sub-millimetre control of director orientation, enabling the preparation of materials with arbitrarily complex director fields. However, without design tools to connect the 2D director pattern with the activated 3D shape, LCE design relies on intuition and trial and error. Here we present a design methodology to generate reliable folding in monolithic LCEs designed with topology optimization. The distributions of order/disorder and director orientations are optimized so that the remotely actuated deformation closely matches a target deformation for origami folding. The optimal design exhibits a strategy to counteract the mechanical frustration that may lead to an undesirable deformation, such as anti-clastic bending. Multi-hinge networks were developed using insights from the optimal hinge designs and were demonstrated through the fabrication and reversible actuation of a self-folding box. Topology optimization provides an important step towards leveraging the opportunities afforded by LCE patterning into functional designs.
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Affiliation(s)
- Kazuko Fuchi
- Aerospace Systems Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7531, USA.
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38
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Abstract
The spontaneous conversion of a flat film into a 3-D shape requires local programming of the mechanical response. Historically, the ability to locally program the mechanical response of high strain (>30%) liquid crystalline elastomers (LCEs) has been limited to magnetic or mechanical alignment techniques, which limits spatial resolution. Recently, we reported on the preparation of LCEs capable of 55% strain with spatial control of the mechanical response at scales as small as 0.01 mm2. Here, we report a distinct formulation strategy to realize programmable stimulus-response in LCEs. Photopolymerization of thiol-ene/acrylate formulations yields materials that exhibit large reversible strain up to 150%. The photopolymerization reaction is extremely rapid, reducing preparation time from days to minutes. The mechanical behavior of these materials can be tuned by varying cross-link density. Spatial and hierarchical programming of the director profile is demonstrated, enabling 3-D shape change, including twisting ribbons and localized Gaussian curvature.
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Affiliation(s)
- Taylor H. Ware
- Materials
and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
- Azimuth Corporation, Beavercreek, Ohio 45431, United States
| | - Zachary P. Perry
- Materials
and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
- Department
of Chemistry and Chemistry Research Center, United States Air Force Academy, Colorado Springs, Colorado 80840, United States
| | - Claire M. Middleton
- Materials
and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
- Azimuth Corporation, Beavercreek, Ohio 45431, United States
| | - Scott T. Iacono
- Department
of Chemistry and Chemistry Research Center, United States Air Force Academy, Colorado Springs, Colorado 80840, United States
| | - Timothy J. White
- Materials
and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
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39
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Abstract
Dynamic control of shape can bring multifunctionality to devices. Soft materials capable of programmable shape change require localized control of the magnitude and directionality of a mechanical response. We report the preparation of soft, ordered materials referred to as liquid crystal elastomers. The direction of molecular order, known as the director, is written within local volume elements (voxels) as small as 0.0005 cubic millimeters. Locally, the director controls the inherent mechanical response (55% strain) within the material. In monoliths with spatially patterned director, thermal or chemical stimuli transform flat sheets into three-dimensional objects through controlled bending and stretching. The programmable mechanical response of these materials could yield monolithic multifunctional devices or serve as reconfigurable substrates for flexible devices in aerospace, medicine, or consumer goods.
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Affiliation(s)
- Taylor H Ware
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, USA. Azimuth Corporation, Dayton, OH, USA
| | - Michael E McConney
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, USA
| | - Jeong Jae Wie
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, USA. Azimuth Corporation, Dayton, OH, USA
| | - Vincent P Tondiglia
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, USA. Leidos, Dayton, OH, USA
| | - Timothy J White
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, USA.
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40
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Affiliation(s)
- Jeong Jae Wie
- Air Force Research Laboratory, Materials
and Manufacturing Directorate, Wright-Patterson
Air Force Base, Ohio 45433-7750, United States
| | - Kyung Min Lee
- Air Force Research Laboratory, Materials
and Manufacturing Directorate, Wright-Patterson
Air Force Base, Ohio 45433-7750, United States
| | - Taylor H. Ware
- Air Force Research Laboratory, Materials
and Manufacturing Directorate, Wright-Patterson
Air Force Base, Ohio 45433-7750, United States
| | - Timothy J. White
- Air Force Research Laboratory, Materials
and Manufacturing Directorate, Wright-Patterson
Air Force Base, Ohio 45433-7750, United States
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