A highly stretchable tri-channel fiber for composite motion decoupling

Fiber electronics have shown considerable potential in various applications, including electronic skin, human-machine interfaces, and intelligent sensing systems. However, stretchable fiber-based strain sensors confront fundamental challenges in concurrently achieving robust mechanical endurance, wide linear response range, and effective composite motions decoupling under complex deformation conditions. Here we present a highly stretchable tri-channel fiber featuring concentric and double-helical microchannels integrated with gallium-based liquid metal, constructing a dual-strain fiber sensor capable of decoupling composite motions involving both elongation and torsional deformations. The helical architecture promotes a three-dimensional orientation of polymer chains, thereby effectively enhancing both the stretchability and cyclic durability of the sensor. Owing to the specific configuration within the fiber, the sensor exhibits a highly linear response to tensile strain, along with bidirectional torsional strain sensing across a wide operational range. Furthermore, by synergistically integrating geometric deformation with hybrid resistive-capacitive sensing mechanisms, the sensor demonstrates the ability to simultaneously monitor and decouple stretching and twisting composite motion behaviors. This strategy enables the precise characterization of object motion and deformation states, offering valuable prospects for real-time health monitoring and motion tracking applications.