A mechanically robust wearable sweat analysis platform with plug-and-play interconnects for continuous biomarker profiling

Reliable electromechanical integration between disposable soft sensors and rigid hardware is crucial for wearable devices, yet physically fragile interfaces often cause severe motion artifacts and contact failures during exercise. To overcome this challenge, this study presents a mechanically robust sweat analysis platform featuring plug-and-play interconnects. Diverging from vulnerable printed inks, a scalable Flexible Printed Circuit Board (FPCB) was engineered with Electroless Nickel Immersion Gold (ENIG) terminals reinforced by a 0.1-mm Polyimide (PI) stiffener. This design ensures highly stable metal-to-metal contact under physical strain. To mitigate chloride corrosion while maintaining the high geometrical consistency of ENIG finishes, a hierarchical architecture was developed utilizing surface-modified carbon as the electrochemical transducer. The system enables accurate detection of lactate (5-80 mM, 0.04046 μA/mM), Na⁺ (12.5-200 mM, 119.59 mV/decade), and equivalent impedance-based sweat rate ( < 0.23 μL/min). Crucially, these robust interconnects facilitated 51 min of uninterrupted monitoring during vigorous aerobic and anaerobic exercises. Based on the acquired data, a proof-of-concept framework mapping sweat rate against lactate concentration was established for personalized exercise intensity zoning, offering a mass-manufacturable paradigm for precision sports physiology.