Flexible wearable hydrogel patch integrated with a "sponge-like" cellulose SERS chip for sweat analysis of urea and...

Recent years have witnessed remarkable progress in cellulose and hydrogels, facilitating the development of wearable green sensing technology. This study presents a novel flexible hydrogel patch designed as a skin-adhesive platform for wearable sensors, synthesized through the strategic integration of hydrogel and porous "sponge-like" technologies. Fabricated from acrylamide and sodium alginate matrices enhanced with tannic acid modification, the composite exhibits superior mechanical performance, biocompatibility (98.75 % cell viability), antimicrobial efficacy (92.03 % inhibition rate against S. aureus), and tissue adhesion. A sulfonated cellulose nanofibril/sodium alginate/silver nanoparticle (S-CNF/SA/Ag NPs) composite membrane was engineered as a surface-enhanced Raman spectroscopy (SERS) detection module, achieving remarkable sensitivity for sweat biomarkers with detection limits of 10^-6 M for urea and 10^-5 M for lactic acid. Experimental validation confirms exceptional epidermal conformability and sustained adhesion. This technological advancement establishes a foundation for transformative applications in personalized healthcare monitoring, exercise physiology assessment, clinical diagnostics, and preventive medicine, thereby accelerating innovation in wearable biosensing platforms.