Abstract: Natural fiber-based artificial muscles represent a class of green and intelligent actuating materials with significant potential for applications in soft robotics and smart textiles. This paper briefly introduces the classification and research landscape of fiber-based artificial muscles, followed by a systematic review of their driving mechanisms, current state of research, applications, and challenges. Natural fibers, with their unique chemical composition and hierarchical anisotropic structures, exhibit remarkable deformation in response to external stimuli such as humidity. Although breakthroughs in actuation performance have been achieved with protein-based and cellulose-based artificial muscles, common challenges persist, including insufficient environmental stability and limited response speed and energy efficiency. Future research should focus on material hybridization, dynamic structural design, and integrated sensing-actuation systems to advance these materials toward high efficiency, stability, and intelligence.

Key words: natural fibers; artificial muscles; humidity response; biomimetic materials; green sustainability