High-performance gelatin-based hydrogel flexible sensor for respiratory monitoring and human–machine interaction

Natural hydrogels like gelatin are ideal for fabricating sensors that monitor human body signals due to their excellent biocompatibility. However, their typically large molecular weight restricts molecular mobility and repositioning under stress, limiting their stretchability performance. In this study, a hydrogel sensor PAM-Gel/β-GP/LiCl (named: PGBL) combining gelatin with ion-complexation, is proposed. Through the synergistic effect of sodium β-glycerophosphate (β-GP) and LiCl, the PAM-gelatin-based hydrogel achieves an extraordinary elongation strain exceeding 11000 %, enabling ultra-stretchability. Additionally, PGBL exhibits excellent electrical conductivity (8.2 S/m), high sensitivity (GF approximately 4.1), and resilience to low temperatures (−24 °C). Moreover, PGBL demonstrates strong adhesion, making it suitable for skin attachment in human body sensing applications. Integrating PGBL hydrogel sensors with a robotic hand has led to the development of a human–machine interaction control system. Furthermore, combining real-time data transmission and visualization technologies has resulted in a real-time respiratory monitoring system, which can monitor sleep apnoea blockage. PGBL hydrogel sensors show promising applications in biomedical fields and biosensing, highlighting their potential in healthcare monitoring systems.