Hydrogel-based Sensors for Multimodal Health Monitoring: From Material Design to Intelligent Sensing

Hydrogels, due to their biocompatibility, tunability, and stimulus-responsiveness, are promising materials for flexible health monitoring. However, traditional hydrogel sensors suffer from limitations in long-term stability, signal fidelity, and integration of advanced functionalities. This review outlines a roadmap for hydrogel-based health monitoring by synthesizing recent advances in material design and intelligent sensing. We analyze strategies for enhancing hydrogel performance (robustness, conductivity, stability, biocompatibility) and detail multimodal sensing mechanisms for physical (strain, pressure, temperature, fluorescence) and chemical (sweat biomarkers, pH, oxygen) signals. The review emphasizes the integration of hydrogels with technologies like: (1) self-powered sensing via triboelectric nanogenerators for autonomous operation; (2) closed-loop diagnosis-therapy platforms; and (3) artificial intelligence (AI) for advanced signal interpretation and diagnostics. These improvements enable applications in epidermal electronics, smart bandages, and implantable devices. Despite progress, challenges remain in environmental stability, integrated multimodal sensing, and clinical translation of implantable systems. Addressing these requires interdisciplinary collaboration to advance hydrogel platforms toward autonomous, personalized, and precision medicine.