Flexible Sensor Based on Fe3O4‐COOH@Ti3C2Tx MXene Rapid‐Gelating Hydrogel for Human Motion Monitoring

Abstract Although hydrogels are still in their infancy, research is primarily focused on optimizing their mechanical, antibacterial, anti‐frost, and water‐retaining properties. However, the rapid preparation of hydrogels without external energy stimulation remains a significant challenge. In this study, a Fe 3 O 4 ‐COOH@MXene@silk fibroin@polyacrylamide hybrid hydrogel (FM@SF‐PAAM) is successfully fabricated using an innovative rapid gelation method, which can initiate the gelation process as low as 7 s and formed at an extremely rapid rate at room temperature, without the use of external energy. The as‐obtained FM@SF‐PAAM hybrid hydrogel exhibits excellent electrical conductivity (6.44 × 10 –2 S m –1 ) and mechanical properties, with a maximum strain of 1660%. Additionally, the FM@SF‐PAAM‐based flexible strain sensor can monitor joint movement and emotional changes, such as finger and elbow bending, glaring, smiling, and mouth opening. Thus, the radical polymerization process demonstrates the immense potential for application to nearly all types of MXene‐based hydrogels and is likely to serve as a foundation for the development of flexible hydrogel‐based devices.