All-flexible chronoepifluidic nanoplasmonic patch for label-free metabolite profiling in sweat.

Wearable sensors allow non-invasive monitoring of sweat metabolites, but their reliance on molecular recognition elements limits both physiological coverage and temporal resolution. Here we report an all-flexible chronoepifluidic surface-enhanced Raman spectroscopy (CEP-SERS) patch for label-free and chronometric profiling of sweat metabolites. The CEP-SERS patch integrates plasmonic nanostructures in epifluidic microchannels for chronological sweat sampling and molecular analysis. An ultrathin fluorocarbon nanofilm modulates surface chain mobility to guide low-temperature solid-state dewetting, forming large-area silver nanoislands on a structured flexible substrate. The wearable patch adheres conformally to skin, collects sequential sweat samples, and supports label-free and multiplexed SERS detection of assorted metabolites. Machine learning-assisted quantification of lactate, uric acid, and tyrosine yields robust metabolic profiles in distinct physical activity states. This wearable optofluidic platform refines molecular sweat sensing and expands the potential for individualized phenotyping in proactive and data-driven healthcare.