Muscle-inspired, high-bandwidth ionic actuators enabled by fibrillar ion-transport networks

Abstract

Conventional Nafion-based ionic actuators suffer from hydration-dependent ion transport and a long-standing trade-off between ionic conductivity and mechanical stiffness, which limits force generation and stable high-frequency operation. Here, we report a PEG-silica-hybridized ionic electroactive Nafion (Ps-iEN) that introduces a mesoscale interfacial ion-transport network via PEG-mediated surface functionalization. This design mitigates ionic liquid-induced matrix softening while preserving efficient ion transport, thereby partially decoupling ionic conductivity from mechanical degradation. Actuators incorporating Ps-iEN exhibit enhanced blocking force at low driving voltages and maintain stable, reproducible actuation up to 50 Hz, together with long-term operational durability exceeding 30,000 cycles in air. The optimized Ps(15)-iEN actuator further demonstrates frequency-encoded motion behaviors that qualitatively resemble distinct contraction regimes in skeletal muscle, including single-twitch, pulsed, and partially fused responses. These results establish Ps-iEN as a performance-oriented electrolyte platform for high-bandwidth ionic actuators and highlight its potential for artificial soft muscles, wearable haptic interfaces, and fiber-integrated soft robotic electronics requiring stable and frequency-tunable actuation.