Fe NWs/CNT/PUS composite constructed rigid-flexible coupling 3D porous structure with highly linear response and large strain for strain sensor

To date, realizing high sensitivity, large strain, and linear response simultaneously using a simple method is significant but challenging. In this study, a rigid-flexible coupled 3D structural strain sensor is established by dip-coating with a polyurethane sponge (PUS), which combines high-modulus iron nanowires (Fe NWs) and flexible carbon nanotubes (CNTs). For the mutual synergistic effect of Fe NWs and CNTs, the flexible strain sensor exhibits excellent linear response (R2 =0.981) with a high gauge factor (GF, ∼7.404) in a large strain range (110%), and good reproducibility up to 50% strain (∼1000 cycles). Besides, fortunately for the fast response time (∼130 ms), the sensor can be applied for human motion detection. Overall, such a rigid-flexible coupling porous structure proposed in this paper leads to an outstanding trade-off of multiple sensing properties above, providing a promising prospect in the field of flexible wearables, etc.