Ultrafast, High‐Contractile Electrothermal‐Driven Liquid Crystal Elastomer Fibers towards Artificial Muscles

Abstract

For example, when an LCE fiber is lifting a heavy load, a high contraction ratio produces a larger displacement and thus a higher external work output. A fast contraction rate, on the other hand, shortens the time required to lift the load and increases the work efficiency of the LCE fiber. In nature, human skeletal muscle can produce larger than 40% contraction at a contraction rate of higher than 50% s −1 , [1,18] allowing it to perform intense movements. For example, when humans are doing sports, e.g., basketball shooting, their muscles can contract both substantially and rapidly. However, none of the LCE fibers reported so far can simultaneously deform with a large contraction ratio and fast contraction rate comparable to human muscles, restricting its applications to conduct intense movements. To date, thermal-responsive LCE fibers are capable of generating large deformation. [19][20][21][22] But the heating rate is limited by the low thermal conductivity of air, leading to a slow contraction of LCE. Second, although light is a precise and fast stimulus, it can only propagate along a straight line. Thus, photo-responsive LCE fibers are usually exposed to light only on one side and typically demonstrate bending deformation, bringing about difficulties to achieve substantial contractile deformation. [23][24][25][26] Overall, with the development of LCE fibers, the gap that LCE fibers can output large contraction at an ultrafast rate needs to be filled.Herein, we report electrothermal-responsive liquid metal (LM) containing LCE (LM-LCE) fibers that can export large contraction with an ultrafast speed. Comparing to rigid conductive fillers, the fluidic property of LM alleviates the restriction to the deformation of LCE, [27,28] ensuring a large contraction generated by LCE. As a high temporal resolution stimulus, the electrical trigger (e.g., voltage value and pulse time) can be adjusted to achieve high instantaneous input of electrical energy and rapidly heat the entire LM-LCE fibers, resulting in a high contraction rate. The electrothermal-responsive LM-LCE fibers can be used as artificial muscles to drive soft robots to perform various functions with intense actuation. Result and DiscussionLM-LCE fibers were fabricated as shown in Figure 1a. First, LCE fibers oriented along the long axis were prepared according to Liquid crystal elastomer (LCE) fibers are capable of large and reversible deformations, making them an ideal artificial muscle. However, limited to stimulating source and structural design, current LCE fibers have not yet achieved both large contraction ratio and fast contraction rate to perform the intense motion. In this work, electrothermal-responsive liquid metal (LM) containing LCE (LM-LCE) fibers is reported. By introducing flexible liquid metal, LM-LCE fibers retain deformability with a large contraction ratio similar to that of pure LCE fibers and are endowed with electrical responsiveness. Applying precisely controlled electrical stimulation, the contraction ratio and rate of LM-LCE fibers ...

Intrinsic carbon nanotube liquid crystalline elastomer photoactuators for high-definition biomechanics

“…S26, ESI†). They were both significantly higher than that of the pure LCE (0.44 MPa), and the maximum actuation stress of the intrinsic CNT/LCE photoresponsive elastomer has exceeded those reported in related studies 30,53,58–60,74–77 on LCE composites (Fig. S27, ESI†) at such a low CNT content.…”

Liquid Crystal Elastomer Twist Fibers toward Rotating Microengines

“…These untethered LCETFs can reversibly generate high torque and large rotational deformation. Fibers made from LCE have been widely exploited as actuators, [25][26][27][28] artificial muscles, [29][30][31][32] and soft robots. [33,34] In this work, we insert twists into LCE fibers Untethered twist fibers do not require end-anchoring structures to hold their twist orientation and offer simple designs and convenient operation.…”

Self-Healable and Recyclable Dual-Shape Memory Liquid Metal–Elastomer Composites

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