High-Performance Strain Sensors Based on Spirally Structured Composites with Carbon Black, Chitin Nanocrystals, and Natural Rubber

In this research, a new type of conductive composite with high tensile strength, high elasticity, and cost competitiveness has been developed through solution mixing–spraying–rolling methods. Naturel rubber (NR) latex with chitin nanocrystals (ChNCs) as reinforcing filler and carbon black (CB) are thermally sprayed on glass substrate layer by layer, and then, spirally structured conductive composites are obtained by rolling the sheets. When the CB content is 4.44%, the conductivity of the NR/ChNCs-CB composite can reach 6.92 s/m. The tensile strength of 5% ChNCs reinforced conductive composites is 3.47 MPa, which is 3.1 times that of NR-CB composites without ChNCs. The strain sensor exhibits a high gauge factor (GF ≈ 5) and electrical conductivity stability in a small deformation range and still shows good stability and recoverability upon 25%, 50%, and 100% strain. The high-sensitivity strain sensors are further employed for monitoring human activities such as finger movements and pronunciation, which shows good reproducibility and reliability. This study provides a routine of preparing highly stretchable and multifunctional strain sensors based on inexpensive raw materials by a simple manner, which opens up new opportunities for the development of stretchable electronic devices.