Carbon Black Nanoparticle/Polydopamine-Coated Core-Spun Yarns for Flexible Strain Sensors

A smart and flexible textile strain sensor was developed based on a commercial core-spun yarn coated with carbon black (CB) nanoparticles and polydopamine (PDA). The morphology of the textile was studied using scanning electron microscopy (SEM), and the distribution of CB and self-polymerized PDA was observed. Thermogravimetric analysis (TGA) revealed the applicable temperature range of the strain sensor. The smart textile showed an outstanding strain sensor response range up to 450%, and its mechanical properties were only slightly reduced as compared to the original textile. The cyclic strain sensor behavior of the smart textile was investigated by stretching the textile 100% for 100 cycles, yielding a stable and durable output electrical signal. Application tests for various human motions were also performed. Finally, two mathematical equations based on tunneling theory were proposed to accurately predict the electrical signal during stretching and to reveal the fundamental properties of the textile. Our findings clearly expand the current knowledge of strain sensors.