morphing, soft architecture, lightweight, and small footprint in the smart and interactive soft robotics. The development of soft actuation technologies mimicking the functionalities of natural muscles is in imperative demand. Despite that challenges still exist to realize muscle-like performances which can be compared to that of the natural muscles in all aspects, artificial muscles have been able to surpass the performance of their natural counterparts in some particular properties. For instance, dielectric elastomer actuators (DEA) are capable of producing strains of >300%; [4] thermal responsive coiled polymer fibers can achieve an impressive specific power of 27.1 kW kg -1 which is 84 times of the peak output power from natural muscle; [5] pressurized fluid actuator can be programmed to transform into complex 3D texture and imitate natural stones and plants; [6] soft magnetic actuators with small feature size can provide multiple locomotive modes of swimming, diving, walking, jumping, and crawling. [7] These latest advancements in the artificial muscles shall be highlighted to inspire approaches and strategies for the future development of artificial muscles.Hitherto, many other interesting mechanisms have also been developed to enable artificial muscles. For example, liquid crystal polymers which change the molecular order under applied stimuli to generate reversible macroscopic actuations, [8][9][10][11][12] chemomechanical actuators which can change shapes in response to chemical stimuli such as humidity, acid, base, and solvent, [13][14][15][16][17][18][19] carbon nanotube (CNT) muscles based on electrochemical reaction or electrostatic force, [20][21][22][23][24] and hydrogel actuators working with osmotic pressure or with incorporated active materials (a review on hydrogel machine has been provided by Liu et al. recently [25] ). Although these devices will not be covered here, more comprehensive reviews summarizing on different kinds of soft actuators can be found in the articles by Madden et al., [3] McCracken et al., [26] Hines et al., [27] and Mirvakili and Hunter. [28] While the initial investigations on artificial muscles have been focused on enabling soft actuators with improved mechanical performances, there is a clear shift in recent years to integrate soft functional electronic devices, including the sensing devices which can perceive external stimulus such as strain, pressure, and temperature etc. and the responding device which can provide interactive feedbacks to the users such as emissive surfaces, color changes, and acoustic outputs etc., to impart mechanical intelligence in the soft actuators. The Artificial muscles are the core components of the smart and interactive soft robotic systems, providing the capabilities in shape morphing, manipulation, and mobility. Intense research efforts in the development of artificial muscles are based on the dielectric elastomer actuators, pneumatic actuators, electrochemical actuators, soft magnetic actuators, and stimulus responsive polymers. Recent ...