A Wearable Strain Sensor Based on Fiber-structured PU/MXene/CNT Composite with Ultra-high Sensitivity and Broad Sensing Range

As the critical branch of wearable sensors, strain sensors with lightweight and high stretchability have been widely demanded in human gesture recognition and robotics engineering. However, most strain sensors cannot simultaneously satisfy the requirements of high sensitivity and a broad detection range, attributed to the poor stretchability and fixed connection of commonly used sensing elements. Here, a single-fiber structure composed of polyurethane (PU) as the stretchable core and MXenes/Carbon nanotubes (CNTs) as the conductive shell was fabricated by wet spinning followed with repeated dip-coating. The obtained highly stretchable fiber exhibited superior strain sensing performance, including ultra-high sensitivity (gauge factor up to 2504.1), a large detection range (up to 250%), and good stability (over 1000 cycles). Furthermore, the PU/MXene/CNT single-fiber strain sensor (SFSS) can be utilized to detect human motion signals, such as folding of finger, bending of wrist, arm and knee. Benefiting from the integrated features of high sensitivity and stretchability, this SFSS promises a great application potential in the field of human gesture recognition and smart robotics.