Meter-Long Spiral Carbon Nanotube Fibers Show Ultrauniformity and Flexibility

Conventional straight fibers spun from carbon nanotubes have rather limited deformability; creating a spiral structure holds the promise to break this shape restriction and enhance structural flexibility. Here, we report up to one meter length threads containing purely single-walled nanotubes twisted into spiral loops (about 1.3 X 10(5) loops per meter) with tunable fiber diameters and electrical conductivity. Because of significant increase of the loop number and long-range homogeneity, the fibers display many unique properties (e.g., self-shrinking and forming extremely entangled structure, fast stretching with great resilience, large-degree axial and lateral deflection, and excellent fatigue resistance) that are difficult to achieve in straight yarns or short helical segments. They also have potential applications as macroscopic fiber-shaped temperature sensors and deformable gas sensors. Our long spiral fibers may be configured into versatile structures such as nanotextiles for developing wearable electronics and multifunctional fabrics.