Construction of Spring-Shaped UHMWPE Fiber-Based Soft Actuators with Stable/Fast Actuating Response and Large Actuating Stroke

Ultrahigh-molecular-weight polyethylene (UHMWPE) fiber-based soft actuators with excellent actuating performance have gained intensive attention in the fields of soft robots, sensors, and intelligent control. However, current advances in UHMWPE fiber-based soft actuators suffer from the inability to construct complex deformations, limited actuating stroke, and slow actuating response, which hinder the multifunctional development of the actuators. Herein, a facile hot stretching processing strategy was employed to enhance the orientation degree, thermal conductivity performance, and thermal stability of the fibers (UHMWPE-D), and on this basis, spring-shaped UHMWPE-D fiber-based soft actuators were endowed with excellent actuating function, including a fast actuating response, a large reversible shrinkage strain (84.36%), and a strong load capacity (150 times the self-weight). The high orientation degree in both amorphous and crystalline regions, yielding significant negative expansibility and high thermal conductivity of the UHMWPE-D fibers, ensured a fast actuating response and high shrinkage strain for the actuator, while the numerous shish crystals endowed the fiber with a high thermal stability during the actuating process, resulting in a high circulatory stability for the soft actuator.