Aziz, S.; Martinez, J. G.; Foroughi, J.; Spinks, G. M.; Jager, E. W. H.

Electrochemically driven twisted/coiled carbon nanotube (CNT) yarn actuators are of great interest in the field of wearable artificial muscle technologies as they induce high-strength. However, due to the need for high activation power, these CNT yarns have limited their feasibility in lightweight and inexpensive smart textiles. An alternative approach is to use conductive polymer coated textile yarns. Here, we demonstrate the hybrid textile yarns that adapt both the mechanical strength of CNT and high conductivity of polypyrrole to provide both strength and actuation properties in terms of applied power. CNT-coated PET textile yarns were mechanically twisted and coiled and subjected to the electrochemical coating of polypyrrole to obtain the hierarchical structures. Once twisted, the polypyrrole coated yarns produce fully reversible 25 degrees/mm rotation in a three-electrode electrochemical system providing +0.4 48 V and -1.0 V (vs Ag/AgCl) of the potential window. The polypyrrole coated coiled yarns generate fully reversible 0.22% contraction strain when operated within the same potential window. The volume alteration of polypyrrole due to the electrochemical charge injection and the helical twisted/coiled structure combined to contribute to the actuation properties. These actuators exhibit high tensile properties with excellent abrasion resistance under extreme shear condition that could match to the requirements for making wearable textile exoskeletons.