Hierarchically interlocked helical conductive yarn enables ultra-stretchable electronics and smart fabrics

Simultaneously achieving high mechanical elasticity and electrical conductivity is essentially required for wearable electronics and smart fabrics. However, great challenges still remain to achieve high electrical conductance under large mechanical deformations due to the “trade-off” effect between them. Herein, inspired by curling structure of climbing plants, hierarchically interlocked helical conductive yarn for ultra-stretchable electronics and smart fabrics was developed, via over-twisting silver nanowires (AgNWs)/MXene multi-dimensional synergistic conductive networks that hierarchically entangled with elastic thermoplastic polyurethanes (TPU) nanofiber networks. High-aspect-ratio 1D AgNWs bridged 2D MXene nanosheets into synergistic interconnected conductive network while interlocked with elastic 3D TPU nanofiber skeleton. Unique hierarchically interlocking effect between highly conductive networks and highly elastic nanofiber networks during the twisting process induced helical conductive yarn simultaneously exhibits excellent mechanical stretchability and electrical conductivity. Excellent intrinsic elasticity of TPU macromolecular chains coupled with its hierarchically helical structure enables the conductive yarn exhibits excellent mechanical stretchability. While the hierarchically interlocked conductive structure ensures the stretchable yarn possess high electrical conductivity which could resist large mechanical deformations during stretching process. The hierarchically interlocked helical conductive yarn could still exhibit high electrical conductivity (1.12 × 105 S/m) even under large mechanical deformations (300%), which effectively avoid the “trade-off” effect. Moreover, the ultra-stretchable conductive yarn exhibits smart responsiveness to multi stimuli (mechanical/electron/light). The helical strain sensor has excellent electromechanical performance with stable GF (1.7) in the 600%–1000% linear range. The hierarchically interlocked helical conductive yarn holds great promise for ultra-stretchable electronics and smart fabrics.