Flexible, rapid self-healing and ultra-sensitive hydrogel sensor with dynamic multi-interactions for human motion detection

Hydrogels are extensively utilized as strain sensors in the domain of wearable devices. However, balancing mechanical properties, adhesion, and self-healing capabilities in hydrogel sensors has consistently been a research challenge. In this study, a novel P(AA-AMPS)/PEI hydrogel was synthesized through a straightforward one-step radical polymerization with acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as monomers, polyethyleneimine (PEI) and AlCl 3 as physical crosslinkers to effectively solve the above challenge. The P(AA-AMPS)/PEI hydrogel demonstrated good mechanical properties with a tensile strength of 42.54 kPa, a high self-adhesion strength to pigskin up to 37.48 kPa, and rapid self-healing efficiency of 100 % after 1 h. The P(AA-AMPS)/PEI hydrogel sensor exhibited good stability, precision, and dependability in real-time monitoring of both subtle and large human movements due to the ultra-high sensitivity (GF values were 5.92, 13.82, and 20.89 within the strain ranges of 0–300 %, 300–600 %, and 600–850 %). It must be noted that the sensing performance of the healed P(AA-AMPS)/PEI hydrogel remained unchanged. The developed hydrogel sensor exhibited promising applications in wearable devices, electronic skin, and human–machine interaction.