Electrically controlled liquid crystal elastomer–based soft tubular actuator with multimodal actuation

He, Qinghua; Wang, Zhijian; Wang, Yang; Minori, Adriane Fernandes; Tolley, Michael T.; Cai, Shengqiang

doi:10.1126/sciadv.aax5746

Cited by 371 publications

(345 citation statements)

References 47 publications

(45 reference statements)

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“…The combination of rubber elasticity with the orientational order of liquid crystals leads to a unique class of materials called LCEs which are promising for applications that requires stimulus response. [166][167][168] LCE-based actuators have been reported in active hinges to interconnect polymeric tiles. The soft composite matter is composed of LCE bilayers with orthogonal director alignment and different nematic-to-isotropic transition temperatures (T NI ).…”

Section: Liquid Crystal Elastomersmentioning

confidence: 99%

Soft Actuators for Soft Robotic Applications: A Review

El‐Atab

Mishra

Al‐Modaf

et al. 2020

Advanced Intelligent Systems

340

224

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The compliant, continuum, and configurable robotics field in general has gained growing interest in the past years especially with the exciting advances in artificial intelligence technology, [1] which could enable various valuable applications ranging from manufacturing to safety and healthcare. [2,3] Soft robots are of notable interest because, unlike their rigid counterpart, they can easily deform while being mechanically resilient, [4,5] adapt to the outer environment without harm to humans, [6] and finally, enable low-cost manufacturing. [7] For robots to interact with the outer environment and complete tasks, a set of sensors and actuators need to be integrated into the system. Soft robots, in specific, present additional challenges because their sensing and actuation devices are generally highly integrated within the body of the robot and its whole functionality. These challenges become even more critical when the soft robot is scaled down to sub-centimeter size as the sensing, power, and data analysis units are moved off-board. As a result, miniaturized soft actuators that respond to various stimuli and show large deformations in addition to mechanical resilience are crucial. These would be particularly promising for application in artificial muscles, microrobots, and micro-manipulators. [8-10] Active and soft materials are promising for this task as they can be actuated through various external stimuli, such as photons, thermal, magnetic and/or electric field. Such materials range from particles, to polymers (either electroactive or shape memory), papers, fluids, shape memory alloys (SMAs), liquid metals, hydrogels, 2D materials, or a combination of these. [6-25] Nevertheless, some materials can be more suitable for a specific set of applications than others; for instance, materials stimulated by the near-infrared (NIR) spectrum are promising for biomedical applications, whereas sunlight-stimulated materials are suitable for nature-inspired soft robots used in outside environments. Various useful metrics are generally used to assess the performance of the actuators; these include the generated stress and strain, Young's modulus or measured stiffness, in addition to their power, work, energy, and force density. In this Review article, however, we focus on the application of the soft actuators in soft robotics where the reported metrics include mode and speed of actuation (or locomotion), power, voltage, current (of the driving signal), lifting force, and weight among others. In this Review article, different active materials that have been developed and used in soft actuators for soft robotics are discussed and grouped by the stimulus that generates the actuation response as shown in Figure 1. The physics of operation, resulting deformations, mechanical resilience, and their pros and cons are presented with a focus on the applications of the different soft

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Section: Liquid Crystal Elastomersmentioning

confidence: 99%

Soft Actuators for Soft Robotic Applications: A Review

El‐Atab

Mishra

Al‐Modaf

et al. 2020

Advanced Intelligent Systems

340

224

View full text Add to dashboard Cite

show abstract

“…Similarly, He et al [ 142 ] prepared an electro-active LCE-based soft tubular actuator. The benefits of the tubular actuator include multiple actuation modes, contraction, bending, and expansion.…”

Section: Applications Of Shape-memory Polymeric Artificial Musclesmentioning

confidence: 99%

“…( b ) An LCE artificial muscle film that could lift a load of 3.92 N by 38% of its initial length. ( c ) Schematic of the soft gripper and grasping and lifting of the vial (50 g) and twisting the cap of a vial (Reprinted (adapted) from Science Advances, Applied Sciences and Engineering [ 142 ]. Copyright (2019), American Association for the advancement of Science).…”

Section: Figurementioning

confidence: 99%

Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Chen

Rehman

et al. 2020

Molecules

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Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via Tm or Tg, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.

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“…In addition, the shape change of LCEs can be effectively manipulated by a spatial control of the director profile that enables complex shape changes even when the LCE is compositionally homogenous [5,6]. These unique characteristics of LCEs promote their utilization as interesting components for developing various types of smart materials and systems, including artificial muscles [7,8], soft robots [9,10], smart coatings [11], and optical [12] and biomedical devices [13].…”

Section: Introductionmentioning

confidence: 99%

Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers

et al. 2020

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Among the various types of shape changing materials, liquid crystal elastomers (LCEs) have received significant attention as they can undergo programmed and reversible shape transformations. The molecular engineering of LCEs is the key to manipulating their phase transition, mechanical properties, and actuation performance. In this work, LCEs containing three different types of butyl groups (n-, iso-, and sec-butyl) in the side chain were synthesized, and the effect of isomeric amine chain extenders on the thermal, mechanical, and actuation properties of the resulting LCEs was investigated. Because of the considerably low reactivity of the sec-butyl group toward the diacrylate in the LC monomer, only a densely crosslinked LCE was synthesized. Most interestingly, the mechanical properties, actuation temperature, and blocking stress of the LCEs comprising isobutyl groups were higher than those of the LCEs comprising n-butyl groups. This difference was attributed to the presence of branches in the LCEs with isobutyl groups, which resulted in a tighter molecular packing and reduced the free volume. Our results suggest a facile and effective method for synthesizing LCEs with tailored mechanical and actuation properties by the choice of chain extenders, which may advance the development of soft actuators for a variety of applications in aerospace, medicine, and optics.

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Electrically controlled liquid crystal elastomer–based soft tubular actuator with multimodal actuation

Cited by 371 publications

References 47 publications

Soft Actuators for Soft Robotic Applications: A Review

Soft Actuators for Soft Robotic Applications: A Review

Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers

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