Wearable Hydrogel\nSERS Chip Utilizing Plasmonic Trimers\nfor Uric Acid Analysis in Sweat

Uric acid is typically measured through blood tests,\nwhich can\nbe inconvenient and uncomfortable for patients. Herein, we propose\na wearable surface-enhanced Raman scattering (SERS) chip, incorporating\na hydrogel membrane with integrated plasmonic trimers, for noninvasive\nmonitoring of uric acid in sweat. The plasmonic trimers feature sub\n5 nm nanogaps, generating strong electromagnetic fields to boost the\nRaman signal of surrounding molecules. Simultaneously, the hydrogel\nmembrane pumps sweat through these gaps, efficiently capturing sweat\nbiomarkers for SERS detection. The chip can achieve saturation adsorption\nof sweat within 5 min, eliminating variations in individual sweat\nproduction rates. Dynamic SERS tracking of uric acid and lactic acid\nlevels during anaerobic exercise reveals a temporary suppression of\nuric acid metabolism, likely due to metabolic competition with lactic\nacid. Furthermore, long-term monitoring correlates well with blood\ntest results, confirming that regular exercise helps reduce serum\nuric acid levels and supporting its potential in managing hyperuricemia.