MXene-Au@Ag Hydrogel Patch as a Wearable SERS Sensor for Multiplexed Sweat Analysis of Uric Acid, Creatinine, and pH

Sweat, as a byproduct of human metabolism, can offer valuable insights for individual health monitoring and disease diagnosis. Traditional sweat detection devices face limitations including poor mechanical performance and low sensitivity. To overcome these challenges, we report a wearable surface-enhanced Raman scattering (SERS) sensor based on MXene-Au@Ag NPs core-shell structures integrated with a polyvinyl alcohol (PVA) hydrogel. The uniform deposition of Au@Ag NPs on MXene nanosheets generated high-density electromagnetic "hot spots," significantly enhancing SERS activity. The PVA hydrogel substrate not only endowed the sensor with excellent flexibility and mechanical stability but also facilitated efficient sweat collection and analyte enrichment. This sensor demonstrated ultrasensitive detection of creatinine (2.7 × 10^-9 M) and uric acid (3.6 × 10^-8 M), with strong linear correlations (<i>R</i>² = 0.993 and 0.997), and could simultaneously monitor sweat pH. Practical trials with human volunteers confirmed the sensor's reliable, real-time quantification of biomarker concentrations and dynamic pH in sweat during exercise, validated using a portable Raman spectrometer. With its high uniformity (RSD = 7.02%), mechanical durability, and stable performance under repeated deformation, this wearable SERS sensor platform holds significant promise for point-of-care testing and continuous health monitoring.