A wearable microfluidic electrochemical sensor integrated with a bio-inspired sweat collector for electrolyte detection and hydration evaluation

Continuous monitoring of human electrolytes is crucial for physiological feedback and accurate assessment of hydration status. Herein, we present a microfluidic electrochemical sensor integrated with a bio-inspired sweat collector that enables rapid sweat sampling. Computational fluid dynamics (CFD) simulations are employed to design dendritic bifurcating channels for the sweat collector, enhancing sampling efficiency. The microfluidic electrochemical sensor features a multilayer stacked architecture, in which polyethylene terephthalate-based functional layers are fabricated via a combination of laser engraving, screen printing, and subsequent assembly through layer-by-layer bonding. This configuration allows for in-situ detection of Na⁺ , Ca²⁺, and K⁺ with near-Nernstian behavior, with sensitivity of 67.3, 38.2, and 66.7 mV/decade, respectively, thereby supporting signal acquisition and reliable transduction for comprehensive sweat analysis. The reliability of continuous monitoring is demonstrated through tracking of electrolyte dynamics across multiple subjects. Furthermore, the microfluidic electrochemical sensor exhibits efficient sweat collection and the potential for monitoring of hydration status.