Undoubtedly, it is an urgent need to develop high-performance artificial muscles in robotics.Artificial muscles generally include different types of rigid and soft artificial muscles. Traditional rigid muscles usually come in two types, that is, cable-type and connecting rod-type. [10] Rigid robots based on rigid muscles are given diversified automated manufacturing assignments in the industrial and agricultural fields, having made considerable contributions to the advancement of these fields. [2,11] However, rigid muscles have poor environmental flexibility, limited degrees of freedom, and complex control due to their rigid and bulky structure. [12][13][14] Hence, soft artificial muscles with flexible shape morphing, high maneuverability, strong environmental adaptability, and low manufacturing cost have emerged. [7,15] Soft robots with soft artificial muscles as their key components have exhibited enormous application possibilities, for example, drug delivery tools, [16,17] flexible grippers, [18,19] and means of soft human-machine interaction (HMI). [20,21] Although great progress has been made on soft artificial muscles, there are still many deficiencies due to their poor bearing capacity, shock vulnerability, and difficulty in precise control. [22][23][24] Moreover, it is worth noting that both rigid and soft muscles usually lack sensing feedback, [25][26][27][28] which limits the working efficiency and reliability of robots, especially those of mobile robots and manipulation robots. Additional sensing elements increase the complexity of the entire system, sacrificing the respective functions or responsiveness and increasing the manufacturing. [29][30][31] Thus, artificial muscles cannot adequately fulfill practical engineering requirements. Consequently, developing an artificial muscle with large shape morphing, high bearing capacity, and deformation perception properties is a tremendous challenge.Actuation, load-bearing, and sensory systems are ingeniously coordinated in animals. [1] For example, human arms include muscles, bones, and sensory nerves (i.e., muscle-bone-nerve system), which combine the functions of large shape morphing, high bearing capacity, and deformation sensing monitor. [32,33] In detail, actuation units are composed of muscles that facilitate manipulation and locomotion combined with the bones. As a result, the actuation of human arms is characterized by a large range of motion and high flexibility. The

Liquid crystal elastomers (LCEs) have shown great potential as soft actuating materials in soft robots, with large actuation strain and fast response speed. However, to achieve the unique features of actuation, the liquid crystal mesogens should be well aligned and permanently fixed by polymer networks, limiting their practical applications. The recent progress in the 3D printing technologies of LCEs overcame the shortcomings in conventional processing techniques. In this study, the relationship between the 3D printing parameters and the actuation performance of LCEs is studied in detail. Furthermore, a type of inchworm-inspired crawling soft robot based on a liquid crystal elastomeric actuator is demonstrated, coupled with tilted fish-scale-like microstructures with anisotropic friction as the foot for moving forwards. In addition, the anisotropic friction of inclined scales with different angles is measured to demonstrate the performance of anisotropic friction. Lastly, the kinematic performance of the inchworm-inspired robot is tested on different surfaces.

In article number 2206342, Hongmiao Tian and co-workers propose a soft-rigid hybrid smart artificial muscle (SRH-SAM), which ingeniously coordinates the actuation, loadbearing, and sensory systems. Based on the SRH-SAM, an advanced approach for a reconfigurable blazed grating plane and a new strategy for controllable attachment/ detachment transformation in the field of bionic dry adhesion are completed. This study exhibits a promising prospect for the development of artificial muscles.