Flexible Wearable Plasmonic Paper-Based Microfluidics with Expandable Channel and Adjustable Flow Rate for Portable Surface-Enhanced Raman Scattering Sweat Sensing

The flexible wearable sweat sensor that enables real-time monitoring and noninvasive sampling is emerging as a new focal point in medical healthcare. It represents an ideal choice for analyzing the constituents in human sweat to assess individual physiological states and potential related diseases. Here, we introduce a flexible wearable plasmonic paper-based microfluidic device based on surface-enhanced Raman spectroscopy (SERS) equipped with a portable Raman spectrometer for continuous in situ monitoring of sweat. Extensible segmented channels regulate fluid flow rates for rapid signal saturation. We validated the molecular permeation and enrichment capability of the plasmonic paper-based sensor and achieved SERS sensing and quantitative analysis of the uric acid concentration and pH value. Considering the complexity of the wearing environment in continuous health monitoring using flexible SERS sensors, we investigated the mechanical performance, optical performance, signal accuracy, long-term stability, and biocompatibility of the device, demonstrating the outstanding wearability and capability for the detection of sweat biomarkers. Additionally, the low manufacturing cost, excellent reproducibility of fingerprint signals, and high sensitivity highlight the applicability of microfluidic SERS paper for wearable sweat analysis. Therefore, SERS wearable technology provides a new approach for real-time detection, disease diagnosis, and personalized health monitoring.