Thermally Drawn Soft Dielectric Elastomer Actuator Fibers

The thermal drawing process, originally developed to fabricate silica-based optical fibers, has recently been adapted to produce polymer-based, multimaterial, and multifunctional fibers. Such fibers integrate electrodes, optical waveguides, microfluidic channels, and biosensors and are emerging as promising platforms for multimodal biointerfaces. Recently, actuation has been achieved within fibers by incorporating functional components such as shape-memory alloys (SMAs), magnetic composites, and tendon wires, expanding their applications to soft robotics and medical catheters. However, such actuator fibers often suffer from high stiffness, limited degrees of freedom, and complex actuation setups due to the use of rigid materials, such as SMA or magnetic setups, for field control. To overcome the limitations of existing thermally drawn fiber-based actuator systems, this study presents the development of all-polymer soft actuator fibers based on dielectric elastomers, designed to provide enhanced mechanical compliance and increased actuation freedom. A thermoplastic polyurethane (PU) elastomer was selected as the primary material due to its compatibility with the thermal drawing process and its electroactive response under applied electric fields. The resulting dielectric elastomer actuator (DEA) fibers exhibit intrinsic softness, with an overall Young's modulus of 37 MPa, enabling electrically controllable actuation modes with high freedom in bending, compression, and three-dimensional-(3D) swirling motions. An estimated compression strain of 1.59% was achieved at a driving frequency of 1 Hz and an electrical field of 2.4 MV/m, which is consistent with literature-reported values. Furthermore, the fibers demonstrated excellent cyclic stability, maintaining a consistent actuation performance over 400 consecutive cycles. This approach provides a promising route toward flexible, scalable, and multifunctional actuator fibers for next-generation applications in soft robotics, biomedical devices, and wearable systems.