Thermomechanically active electrodes power work-dense soft actuators

Martinez, Angel; Clement, Arul; Jun-feng, Gao; Kocherzat, Julia; Tabrizi, Mohsen; Shankar, M. Ravi

doi:10.1039/d0sm01399d

Cited by 9 publications

(11 citation statements)

References 26 publications

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“…[ 14 ] Mixtures were harnessed containing a 1:1.2 mole ratio of RM82: EDDT were used to create monodomain LCE using the procedure utilized in the prior work. [ 13 ] The procedure is detailed in the Supporting Information, along with the structure of the monomers (Figure S1, Supporting Information) and the polarized optical microscopy images of the crosslinked films (Figure S2, Supporting Information). Dynamic mechanical analysis was performed using a Perkin Elmer 8000 system with the loading applied along the molecular director.…”

Section: Methodsmentioning

confidence: 99%

“…The lengths were measured along the director. The inflection point of the strain-temperature curve, where the strain production per temperature increase is the highest was characterized (the nominal T ni : nematic-isotropic transition [13,21] ).…”

Section: Methodsmentioning

confidence: 99%

“…Actuation at low voltages is offered by liquid crystalline polymers. [13,14] These materials possess highly ordered microstructures in which mesogenic molecules are orientationally aligned along the nematic director. The molecular order can be programmed by various means, including alignment layers, external fields, and mechanical deformation, while retaining responsivity to stimuli, such as light and heat.…”

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confidence: 99%

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Molecularly Directed, Geometrically Latched, Impulsive Actuation Powers Sub‐Gram Scale Motility

Jun-feng

Clement

Tabrizi

et al. 2021

Adv Materials Technologies

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Transversely curved composite shells of liquid crystal elastomer and polyethylene terephthalate with innervated electrodes present millisecond‐scale actuation with ≈200 mW electrical power inputs at low voltages (≈1 V). The molecular orientation is aligned to direct the thermomechanical work‐content to evert the native curvature. When powered, the curved structure initially remains latent and builds up strain energy. Thereafter, the work content is released in an ms‐scale impulse. The thin‐film actuators are powered against opposing loads to perform up to 10−5 J of work. High speed imaging reveals tip velocities of several 100 mm s−1 with powers approaching 10−4 J s−1. The design eschews bistability. After snap‐through, when the power is off, the actuator spontaneously resets to its native state. The actuation profiles are functions of the geometry and the electrical pulse patterns. The latency of actuation is reduced by powering the actuators with pulses that trigger snap‐through, allow its reset to the native state, but prevent its cooling to the ambient before subsequent actuation cycles. The actuation is harnessed in sub‐gram scale robots, including water‐strider mimicking configurations and steerable robots that can navigate on compliant (sand) and hard (slippery) surfaces. A viable template for impulsive actuation using frugal electrical power emerges.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Molecularly Directed, Geometrically Latched, Impulsive Actuation Powers Sub‐Gram Scale Motility

Jun-feng

Clement

Tabrizi

et al. 2021

Adv Materials Technologies

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“…[ 205 ] In addition to carbon‐based additives, LM–LCE composites have also been explored, taking advantage of the compliancy of LM to achieve a conductive, mechanically unconstrained LCE. [ 210–212 ] Ford et al demonstrated that even with a significantly high LM wt loading of 50% in an LCE, its actuation capabilities were still retained (Figure 8C). [ 210 ] These composites possessed damage detection capabilities and were able to actuate despite sustaining significant punctures.…”

Section: Materials Developments For the Active Layermentioning

confidence: 99%

Soft Actuator Materials for Electrically Driven Haptic Interfaces

Ankit

Nirmal

et al. 2021

Advanced Intelligent Systems

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Haptics involves human touch sensing and tactile feedback and plays a crucial role in physical interactions of humans with their environment. There is an ever‐increasing interest in development of haptic technologies, due to their role in various applications such as robotics, virtual and augmented reality, healthcare, and smart electronics. Electrically driven actuation mechanisms for soft materials like dielectric elastomer actuators (DEAs), electrohydraulic soft actuators (ESAs), ionic polymer−metal composites (IPMCs), and liquid crystal elastomers (LCEs) hold the potential for the development of the next generation of haptic feedback devices due to a variety of advantages such as light weight and compact design, untethered activation and control, large actuation strains, and distributed and localized actuation. Herein, a detailed look is taken at the advancement in material designs for these electrically driven soft actuators. A detailed analysis of the different strategies for improving the electromechanical performance of existing material systems is presented. Approaches adopted to synthesize novel material systems are explained. Advancements in compliant electrode materials for the electrically driven soft actuators are also described. The conclusion reflects on the main challenges in the field and provides perspectives on recent advancements expected to have a significant impact.

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“…There are two basic criteria for elastomers with supreme mechanical adaptability, namely, the sufficiently high tensile strength at the onset of stress plateau and the length of the stress plateau. Most research on liquid crystal elastomers focuses on developing environmental response materials, such as temperature, light, and magnetic responsiveness [28][29][30][31]. And the mechanical tensile strength in previous literatures almost never exceeds 1 MPa [7,17,19,30,31].…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystal-Based Organosilicone Elastomers with Supreme Mechanical Adaptability

et al. 2022

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Elastomers with supreme mechanical adaptability where the increasing stress under continuous deformation is significantly inhibited within a large deformation zone, are highly desired in many areas, such as artificial muscles, flexible and wearable electronics, and soft artificial-intelligence robots. Such system comprises the advantages of recoverable elasticity and internal compensation to external mechanical work. To obtain elastomer with supreme mechanical adaptability, a novel liquid crystal-based organosilicon elastomer (LCMQ) is developed in this work, which takes the advantages of reversible strain-induced phase transition of liquid crystal units in polymer matrix and the recoverable nano-sized fillers. The former is responsible for the inhibition of stress increasing during deformation, where the external work is mostly compensated by internal phase transition, and the latter provides tunable and sufficient high tensile strength. Such LCMQs were synthesized with 4-methoxyphenyl 4-(but-3-en-1-yloxy)benzoate (MBB) grafted thiol silicone oil (crosslinker-g-MBB) as crosslinking agent, vinyl terminated polydimethylsiloxane as base adhesive, and fumed silica as reinforcing filler by two-step thiol-ene “click” reaction. The obtained tensile strength and the elongation at break are better than previously reported values. Moreover, the resulting liquid crystal elastomers exhibit different mechanical behavior from conventional silicone rubbers. When the liquid crystal content increases from 1% (w/w) to 4% (w/w), the stress plateau for mechanical adaptability becomes clearer. Moreover, the liquid crystal elastomer has no obvious deformation from 25 °C to 120 °C and is expected to be used in industrial applications. It also provides a new template for the modification of organosilicon elastomers.

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Thermomechanically active electrodes power work-dense soft actuators

Abstract: The effect of chain extender structure and composition on the properties of liquid crystal elastomers (LCE) is presented. Compositions are optimized to design work-dense liquid metal LCE composites that are operated with 100 mW power.

Cited by 9 publications

References 26 publications

Molecularly Directed, Geometrically Latched, Impulsive Actuation Powers Sub‐Gram Scale Motility

Molecularly Directed, Geometrically Latched, Impulsive Actuation Powers Sub‐Gram Scale Motility

Soft Actuator Materials for Electrically Driven Haptic Interfaces

Liquid Crystal-Based Organosilicone Elastomers with Supreme Mechanical Adaptability

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