Electrochemically Powered, Energy‐Conserving Carbon Nanotube Artificial Muscles

While artificial muscle yarns and fibers are potentially important for many applications, the combination of large strokes, high gravimetric work capacities, short cycle times, and high efficiencies are not realized for these fibers. This paper demonstrates here electrochemically powered carbon nanotube yarn muscles that provide tensile contraction as high as 16.5%, which is 12.7 times higher than previously obtained. These electrochemical muscles can deliver a contractile energy conversion efficiency of 5.4%, which is 4.1 times higher than reported for any organic‐material‐based artificial muscle. All‐solid‐state parallel muscles and braided muscles, which do not require a liquid electrolyte, provide tensile contractions of 11.6% and 5%, respectively. These artificial muscles might eventually be deployed for a host of applications, from robotics to perhaps even implantable medical devices. Electrochemically driven all‐solid‐state artificial muscle actuates by the migration of ions from the surrounding electrolyte into the electrochemical double layer of two‐ply coiled carbon nanotube yarn. Tensile stroke and contractile work capacity are −11.6% and 1.12 J g−1, respectively, which is ≈30 times the work capacity of human skeletal muscle.