The interest in soft robotics has experienced a continuous growth in recent years. Building soft actuators to develop precise machines that can overcome or assist human manufacturing ability represents a great challenge for the scientific community [1]. One promising application is the use of soft actuators in artificial muscles, which can replace biological or mechanical components with high energy conversion efficiency. Artificial muscles can rely on shape memory polymers capable of temporarily changing shape and returning to their original form when triggered by external factors like heat, light, moisture, or magnetic fields [2]. Light-responsive and electro-responsive shape-changing materials are of particular interest, with ongoing research focusing on their structure, properties, and fabrication methods.

This talk focuses on developing electrospun soft actuators designed to respond to various stimuli. The fibers consist of a shape memory system based on a crosslinked poly(ε-caprolactone) (PCL) network with silica-based netpoints [3]. These fibers demonstrated both one-way and two-way shape memory behavior triggered by thermal stimuli. To confer photo-responsiveness, an azobenzene compound (AZO) was included. The AZO compound undergoes rapid thermal cis-to-trans isomerization, facilitated by push-pull electron-donating/withdrawing substituents [4]. In another approach, the shape memory fibers were coated with silver nanoparticles to impart electro-responsiveness. Shape memory actuation in the AZO-loaded fibers is induced by the photothermal effect, while in the Ag-coated fibers, it is induced by the Joule effect. Temperature during either UV irradiation or electrical stimulus was carefully monitored, and significant differences in actuation performance were found among randomly arranged non-woven electrospun fibers, aligned fibers, and bulk films. The shape memory system was further modified by a proper polymer coating to achieve also stress-free shape memory effect. Finally, examples of electrospun actators based on liquid-crystalline phases will be also provided. Overall, this talk offers insights into designing and characterizing photo-responsive and electro-responsive shape memory materials for potential applications across various fields.