▎ 摘　　要

Highly stretchable and conductive core-sheath nanofibers are significant for flexible and wearable micro-electronics. Core-sheath fibers were massively fabricated from ultralong chemical vapor deposition (CVD)-grown graphene bundles. They exhibited superior conductivity and excellent mechanical properties that exceeded those of the reduced graphene oxide fibers. The intrinsic dynamic fracture procedure and mechanism of the core-sheath nanofibers were investigated. Furthermore, safe strain sensors based on as-prepared core-sheath CVD graphene fibers have been demonstrated as a proof-of-concept application. The performance of strain sensors has been greatly improved by using CVD 2 3 4 graphene fibers.