Wearable Colorimetric Microfluidic Sensor Integrated with Localized Unidirectional Sweat-Wicking Nanofiber Membrane for Multianalyte Sweat Analysis

Abstract Wearable sweat sensors have emerged as promising platforms for noninvasive health monitoring; however, inefficient sweat collection and uncontrolled fluid transport remain major challenges that limit their practical application. Here, we report a wearable colorimetric microfluidic sweat sensor integrated with a localized Janus TPU nanofiber membrane (CMS-LJNM) that enables efficient sweat collection and directional transport. The Janus membrane, featuring patterned hydrophilic−hydrophobic regions, facilitates passive and rapid unidirectional sweat transport from the skin surface to the microfluidic chip while suppressing lateral spreading. The flexible microfluidic chip incorporates capillary burst valves to precisely regulate sweat flow and prevent cross-contamination between sensing chambers. The device integrates multiple colorimetric sensing units for the simultaneous quantification of key sweat biomarkers, including glucose, urea, chloride ions, and pH, requiring only 2 μL of sweat for complete analysis. All sensing units exhibited good linearity within physiological concentration ranges and excellent anti-interference performance, and the results could be conveniently quantified through smartphone-based image analysis. On-body tests involving six volunteers demonstrated reliable sweat collection and detection, with results showing strong agreement with conventional analytical methods. This work provides a promising strategy integrating efficient directional sweat transport with precise microfluidic-based multianalyte detection, facilitating practical sports monitoring and sweat-based physiological analysis.