Wearable nanoplasmonic sensor based on surface-enhanced Raman scattering for multiplexed analysis of sweat

Wearable sweat sensors that enable non-invasive sampling, efficient and rapid detection, and real-time monitoring capabilities have become an integral and critical component of human health management, with the potential to provide meaningful clinical information related to physiologic diseases in the healthcare field. Here, a flexible nanoplasmonic paper-based sensor based on surface-enhanced Raman scattering (SERS) was developed, in which silver nanoparticles were loaded in the cellulose paper to enhance the Raman signals of targets via the generation of SERS “hotspots.” By incorporating the filter paper channel with a natural core absorbing liquid, the multifunctional chip is formed, which integrates the collection, transmission, and detection of trace sweat. This paper-based chip is soft and stretchable, and fits perfectly onto the human skin surface without causing any damage or irritation. Combined with a hand-held Raman spectrometer, quantitative detection of multiple sweat components can be achieved with the limit of detection of 17 and 1 μmol/L for uric acid and glucose, respectively, and the measurable range is 4–7.5 for pH, enabling wearable and in-situ optical sensing for sweat markers under the condition of human physiology and pathology, within only 5 min for uric acid and glucose detection. This wearable biosensor would provide, to our knowledge, a new way for continuously monitoring the health status by collection and analysis of multiple components in human sweat, contributing to point-of-care testing and personalized medicine applications.