Bio-Friendly Artificial Muscles Based on Carbon Nanotube Yarns and Eutectogel Derivatives

Abstract

This study introduces a novel class of bio-friendly, solid-state artificial muscles based on commercially available coiled carbon nanotube (CNT) yarns coated with eutectogel derivatives incorporating dilutions of deep eutectic solvents (DES). By combining polyanionic and polycationic gels based on DES, synchronized contraction of the two yarn electrodes is achieved via selective ion intercalation and enables unipolar actuation in solid-state CNT yarn actuators. The studies on the electrochemical properties of the actuator show that the contractile stroke and the stroke-to-charge ratio increase as the amount of ionic units in the polymers increases. At high ionic monomer content, evidence of an early scan-rate-enhanced-stroke (SRES) effect can also be observed. The solid-state actuator reaches a contractile stroke of 2.25% under a 90 mN load and remains stable over 300 cycles in ambient conditions. Textile integration through inlaying preserves actuator functionality, achieving up to 3.4% strain, demonstrating excellent compatibility with smart wearable platforms. These results highlight the potential of DES-based gel coatings for the scalable development of unipolar, high-performance, and environmentally sustainable artificial muscles suitable for e-textiles, soft robotics, and prosthetics.