Wearable Microneedle Patch Integrated with Metal Hydrogel‐Based Signal Probe for Dermal Interstitial Fluid Protein Biomarkers Monitoring

Real-time tracking of protein biomarkers in dermal interstitial fluid (ISF) remains a significant challenge due to the limitations in robust analyte sensing, efficient ISF extraction, and seamless system integration. Herein, a wearable microneedle patch (w-MN patch) integrated with a metal hydrogel-based electrochemical probe is demonstrated for simultaneous sampling and monitoring of immunoglobulin G (IgG), a key protein biomarker, in ISF. The sensing probe, featuring ferrocene anchored on polydopamine functionalized-Au gel, enables highly stable and sensitive detection with an ultralow detection limit of 0.05 ng mL^‒1 in both in vitro and ex vivo models. A hollow MN (HMN) array design facilitates rapid ISF collection, yielding 5.6 µL within 5 min in a live rat model, as validated by simulations and experimental data. By integrating the HMN array via a sensing chip using a home-made packaging chamber, the w-MN patch realizes real-time, wireless IgG monitoring in vivo. This work presents a fully integrated platform that unites sensitive protein biomarker detection, efficient ISF extraction, and wearable device engineering, offering significant potential for precision diagnostics and next-generation wearable healthcare technologies.