PAM-co-VI-based bimetallic-doped single-network conductive hydrogel for stress sensing and ECG signal monitoring applications

Polyacrylamide (PAM) based hydrogels are promising for soft strain sensor applications, while the incorporation of vinylimidazole (VI) endows the hydrogels with unique ion responsiveness and good biocompatibility. In this study, a high-performance PAM-co-VI/Ni/Co hydrogel was successfully fabricated through copolymerization of PAM with VI followed by modification with bimetallic nickel-cobalt ions. Experimental results demonstrate that when the VI content is 30% with a Ni/Co ion ratio of 3:1, the hydrogel exhibits remarkable comprehensive properties, with a tensile fracture strength of 0.46 MPa, an ultrahigh fracture strain of 1800%, a tensile sensitivity of 4.62, and long-term durability exceeding 1000 cycles. Furthermore, the hydrogel shows high pressure sensitivity (0.059 kPa -1 in the 0-5 kPa range), enabling precise detection of various mechanical signals from acoustic vibrations to complex human motions. Owing to its superior conductivity and biocompatibility, the PAM-co-VI/Ni/Co hydrogel also functions as a flexible electrode for electrocardiogram (ECG) monitoring, achieving conformal skin contact while stably acquiring high signal-to-noise ratio ECG waveforms with accurate identification of P-waves, Q, R, and S waves (QRS complexes), and other key features, demonstrating great potential for wearable health monitoring applications. • Innovative PAM-co-VI/Ni/Co hydrogel with ion responsiveness and biocompatibility was fabricated. • The hydrogel exhibited high mechanical properties. • The hydrogel has precise sensing of acoustic vibrations to human motions. • The hydrogel is ideal for wearable health monitoring with integrated performances.