Coiled polymer fibers for artificial muscle and more applications

Coiled polymer fibers are promising materials that can be used in powerful artificial muscles. When external stimuli appear (e.g., changes of electrical field, humidity, light, temperature, etc.), these fibers can have an axial contraction. Thanks to diverse polymer chemical structures, tunable polymer aggregated structures, and the twist geometric construction of coiled polymer fibers, coiled-polymer-fiber-based artificial muscles (including smart grippers, soft robotics, and smart textiles) show remarkable and promising performance. In addition to artificial muscles, coiled polymer fibers also exhibit great potential for use in refrigerators, sensors, and more. In this perspective, advantages of coiled polymer fibers are discussed in terms of diverse polymer chemical structures, tunable polymer aggregated structures, and the twist geometric construction of coiled polymer fibers. Recent progress in the applications of coiled polymer fibers in artificial muscles and more devices is also reviewed. Finally, possible future research directions of emerging coiled polymer fibers are proposed.