A Soft Actuator with Simultaneous Ultra‐High Actuation Strain and Power Density Under Human‐Safe Stimuli

Diverse soft robotic applications, such as wearable devices, haptic interfaces, artificial muscles, and biomedical systems, require soft actuators to simultaneously deliver large actuation strain (>40%) and high power density (>323 W kg −1 ) in response to mild, human‐safe stimuli. However, no existing soft actuator system has successfully met these combined requirements. To address this critical gap, body‐temperature‐responsive liquid crystalline elastomer (LCE) films are designed with a thickness direction orientation gradient achieved through macromolecular engineering of lightly crosslinked gels during the initial stage of network formation. Using ultrahigh stretch ratios to 2000% and with controlled entropic recovery, the degree of molecular orientation through the film thickness can be established. As a result, the fully crosslinked monodomain LC soft actuator simultaneously provides a high actuation strain of 88% and a high power density of 1960 W kg −1 under body‐temperature stimulation, a level of performance unmatched by existing actuators sensitive to mild stimuli. Device‐level demonstrations, including a rotary soft robot and an intelligent safety switch, highlight the actuator's versatility and potential for real‐world integration in next‐generation soft robotic systems.