Multilayer Core‐Shell Fiber Device for Improved Strain Sensing and Supercapacitor Applications

Abstract 1D fiber devices, known for their exceptional flexibility and seamless integration capabilities, often face trade‐offs between desired wearable application characteristics and actual performance. In this study, a multilayer device composed of carbon nanotube (CNT), transition metal carbides/nitrides (MXenes), and cotton fibers, fabricated using a dry spinning method is presented, which significantly enhances both strain sensing and supercapacitor functionality. This core‐shell fiber design achieves a record‐high sensitivity (GF ≈ 4500) and maintains robust durability under various environmental conditions. Furthermore, the design approach markedly influences capacitance, correlating with the percentage of active material used. Through systematic optimization, the fiber device exhibited a capacitance 26‐fold greater than that of a standard neat CNT fiber, emphasizing the crucial role of innovative design and high active material loading in improving device performance.