Hofmeister effect guided dual-crosslinked sodium alginate-based hydrogel with super-stretchable, self-adhesive, and antibacterial properties for flexible sensors in human activity monitoring

The integration of high ionic conductivity and mechanical robustness in hydrogels for wearable applications remains a significant challenge. In this work, we present a simple approach for fabricating sodium alginate-based hydrogels OSA-g-P(AA-co-MBA)/Li⁺ using Hofmeister effect-driven dual-crosslinking strategy. This approach enables the hydrogel to achieve tunable mechanical and electrical properties, making it ideal for flexible sensors in human activity monitoring. By incorporating Li⁺ and optimizing the crosslinking density, The hydrogel demonstrates remarkable stretchability with up to 1596 % elongation and exhibits antibacterial properties against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The dynamic bonds formed by aldehyde groups endow the material with self-healing capabilities. In flexible sensing applications, OSA-g-P(AA-co-MBA)/Li⁺ shows outstanding strain sensitivity, enabling real-time monitoring of human motion and other physiological activities. Furthermore, OSA-g-P(AA-co-MBA) hydrogel demonstrates rapid temperature-responsive behavior, with its transparency changing in response to temperature variations, offering potential for applications that require dynamic material properties. With its outstanding mechanical performance, high strain sensitivity, and self-healing abilities, this hydrogel presents a promising platform for next-generation wearable sensors and flexible electronic devices.