Biomimetic, biocompatible and robust silk Fibroin-MXene film with stable 3D cross-link structure for flexible pressure sensors

The ever-increasing demand for flexible electronics has considerably stimulated the desire for high-performance, safe, and durable sensing materials. Preparation of flexible active films with biocompatibility and high performance remains a challenge because of the complexities of large-scale production and the use of toxic chemicals. Here we demonstrated flexible silk fibroin@Ti3C2Tx MXene (SF@MXene) biocomposite films with a threedimensional (3D) cross-link structure, utilizing natural silk fibroin (SF) as a bridging agent to self-assembled two-dimensional (2D) MXene nanosheets into a continuous wave-shaped lamellar macrostructure. The material exhibited good biocompatibility in a cytotoxicity test, thereby reducing the risk when applied to the human body. The SF@MXene biocomposite film provides a biomimetic 3D cross-link structure, resulting in low elastic modulus (1.22 MPa), good sensitivity (25.5 kPa(-1)), fast response/recovery time (40/35 ms), subtle pressure detection of limit (9.8 Pa), and good stability (3500 cycles). In addition, this pressure sensor can be applied to human health monitoring, including pulse feeling analysis, acoustic sound, deglutition swallowing, and finger motion. The synthesis of the SF@MXene biocomposite film offers a widely applicable material for developing safe and high-performance flexible electronics.