All-Flexible Chronoepifluidic Nanoplasmonic Patch Allows Label-free Sweat Profiling

Wearable sweat sensors allow non-invasive metabolic profiling for timely intervention in proactive healthcare. However, molecular recognition elements in conventional sensors still hinder a comprehensive understanding of an individual's unique physiological profile. Here we report an all-flexible chronoepifluidic surface-enhanced Raman spectroscopy (SERS) patch (CEP-SERS patch) for label-free sweat profiling. The CEP-SERS patch features the integration of nanoplasmonics and functional microfluidics for precise chronological profiling of metabolites. An ultrathin fluorocarbon film facilitates large-area nanofabrication of plasmonic structures on a functional microfluidic channel via low-temperature solid-state dewetting of a thin silver film. The CEP-SERS patch facilitates conformal contact on human skin and SERS detection of diverse metabolites from sequentially sampled sweat. Machine-learned quantification of metabolites including lactate, uric acid, and tyrosine has successfully profiled SERS detection of sweat during assorted physical activities. This CEP-SERS patch can provide a new strategy for delineating the physiological phenotype of individuals in personalized healthcare.