Highly stretchable, durable, and superfine fiber-shaped strain sensor with a porous core-sheath microstructure

A stretchable fiber-shaped strain sensor benefits from its high aspect ratio and can be easily integrated into textiles, which has attracted extensive attention. Introducing microstructures such as porous or buckling microstructures into elastic fibers are often used to obtain high-performance strain-sensing fibers. However, the fabrication of high-performance superfine fiber-shaped strain sensor still faces the difficulty of preparing controllable microstructures on the surface of the fiber. In this work, we propose a breath figure method to fabricate CNTs/SEBS film with porous microstructure on the polyurethane fiber (PU fiber). By adjusting the process parameters, the morphology of the porous microstructure can be controlled conveniently. The optimized fiber-shaped strain sensor has a superfine diameter (58 μm), large detection range (240%), low strain detection limit (0.025%), high sensitivity (GF of 1439.83 at 230 %–250%), fast response time (≈62.7 ms), and excellent stability with 100,000 cycles at a large deformation of 100%. Finally, the fiber-shape strain sensor was sewn into the textile to verify its application in gesture recognition, breath sensing and limbs activity monitoring. This work proposes a simple and efficient strategy to realize the superfine fiber-shaped strain sensor with controlled porous microstructure, which has great potential in the field of wearable electronic devices.