Electrical Double-Layer-Driven Actuation of Individual Electrospun Elastomeric Fibers

Nanoscale soft actuators are attracting increasing interest for microrobotics, biointerfaces, and adaptive materials; however, reliable actuation mechanisms at nanometer dimensions remain scarce. Here, we demonstrate axial electro-actuation of dielectric elastomer fibers driven by electrostriction using an electrochemical approach. A driving voltage applied to a gold electrode sputter-deposited onto the sub-micron fiber induces ionic double-layer formation, establishing a stable electric field across the dielectric fiber without electrical breakdown. The resulting electrostriction-driven deformation is quantified by modulated electrochemical force microscopy, revealing a cubic electric-field dependence consistent with electrostriction and RC-limited dynamics governed by ionic transport. Measurements with fibers of varying diameters (400 nm-4.4 μm) show enhanced actuation at smaller scales, confirming a stable scaling law for electrostriction down to submicrometric dimensions. For electrospun polyurethane fibers, we determine an electrostriction coefficient of M31 = (2.9 ± 0.6) × 10-17 m2/V2, establishing electrostriction as a viable mechanism for submicron scale dielectric fiber actuators in electrochemical environments.