Strong and Robust Electrochemical Artificial Muscles by Ionic‐Liquid‐in‐Nanofiber‐Sheathed Carbon Nanotube Yarns

Abstract

To address the lack of a suitable electrolyte that supports the stable operation of the electrochemical yarn muscles in air, an ionic‐liquid‐in‐nanofibers sheathed carbon nanotube (CNT) yarn muscle is prepared. The nanofibers serve as a separator to avoid the short‐circuiting of the yarns and a reservoir for ionic liquid. The ionic‐liquid‐in‐nanofiber‐sheathed yarn muscles are strong, providing an isometric stress of 10.8 MPa (about 31 times the skeletal muscles). The yarn muscles are highly robust, which can reversibly contract stably at such conditions as being knotted, wide‐range humidity (30 to 90 RH%) and temperature (25 to 70 °C), and long‐term cycling and storage in air. By utilizing the accumulated isometric stress, the yarn muscles achieve a high contraction rate of 36.3% s−1. The yarn muscles are tightly bundled to lift heavy weights and grasp objects. These unique features can make the strong and robust yarn muscles as a desirable actuation component for robotic devices.

Bioinspired Construction of Artificial Cardiac Muscles Based on Liquid Crystal Elastomer Fibers

“…Yunpeng Wang, Wei Liao, Jiahao Sun, Rajib Nandi, and Zhongqiang Yang* DOI: 10.1002/admt.202100934 natural muscles. [2,3] The stimuli-responsive materials utilized as artificial muscles were well-reviewed previously. [4,5] As an important type of stimuli-responsive materials, liquid crystal elastomer (LCE) exploited as artificial muscles aroused increasing attention, [6][7][8] which is mainly attributed to significant and reversible uniaxial deformation resulted from the change of mesogenic alignment upon external stimuli, eg.…”

“…[19][20][21] Among artificial muscles, LCE possesses outstanding performance especially due to its significant deformation and reliable reversibility. [3] The actuation of LCE materials is based on the monodomain alignment of mesogenic units, which are induced by the currently developed strategies such as physical stretching, [22][23][24] surface inducement, [25][26][27] or external fields inducement. [28][29][30] Previous work has utilized LCE to mimic skeletal and smooth muscles, for example, LCE contraction mimics the deformation of biceps to lift weights, [31][32][33] or LCE tubular contraction mimics vascular peristalsis to manipulate fluid.…”

“…With the well-aligned LCE fibers in hand, we next evaluated the performance of LCE fibers and made a comparison with human muscle fibers. [3] As shown in Table 1, six metrics including density, modulus, actuation strain, actuation stress, work density, and specific power were illustrated. It could be seen that the LCE fibers established in our work possessed a Table 1.…”

“…It could be seen that the LCE fibers established in our work possessed a Table 1. Mechanical properties for human muscle fibers, [3] Artificial cardiac muscles composed of LCE fibers were constructed by mimicking the configuration of cardiac muscle fibers to achieve sophisticated shape morphing, that is, beating. In human heart, cardiac muscle fibers consisting of circular and helical patterns undergo contract and twist motions simultaneously.…”

Fast Sheath-driven Electrothermal Artificial Muscles with High Power Densities

“…Arti cial muscles that convert external energy to mechanical energy are of great interest because of their potential applications in devices like exoskeletons, prostheses, and bionic robots. Many functional materials have been used as arti cial muscles, such as shape memory polymers (SMPs) 1,2 , shape memory alloys (SMAs) 3 , dielectric elastomers (DEs) [4][5][6][7][8] , polymer bers [9][10][11] , ionic polymer metal composites (IPMCs) 12,13 , graphene based bers [14][15][16] , and carbon nanotubes (CNTs) [17][18][19][20][21] . CNT yarns are especially promising candidates due to their high strokes, electrical conductivity, thermal conductivity, and mechanical strength 22,23 .…”