Quantitative surface-enhanced Raman spectroscopy analysis of sweat integrated with a skin-mounted soft microfluidic reactor

Surface-enhanced Raman spectroscopy (SERS) has great promise for noninvasive biosensing; however, challenges in signal reproducibility and hotspot uniformity limit its quantitative application in wearable formats. This study presents a dual readout sensing platform that integrates SERS and colorimetric assays within a soft, skin-conformal microfluidic reactor for the quantitative analysis of sweat biomarkers. In response to target analytes, an enzymatic reaction system generates malachite green (MG), a Raman and color active compound, while rhodamine 6 G (R6G) serves as a preloaded internal standard to normalize SERS signals. The integration of optical and spectroscopic modalities enables internal cross-validation, improving overall sensing reliability in dynamic environments. The device also enables real-time visual indexing through MG’s concentration-dependent color development, quantified using ΔEab values in the CIELAB color space to mitigate lighting variability. Statistical sampling across SERS reservoirs further enhances signal stability. Benchtop and on-body trials involving thirteen participants demonstrate physiologically consistent quantification under dynamic conditions. The combined strategies offer a robust and reproducible framework for bimodal sensing, highlighting the potential of this platform for practical deployment in wearable diagnostics and personalized health monitoring. All the clinical trial was prospectively registered in the Korea Clinical Research Information Service (CRIS), which is a WHO ICTRP–recognized primary registry (KCT0011366). The study protocol was prospectively registered at ClinicalTrials.gov (NCT07342387).