Hydrogel bioinks for extrusion-based 3D bioprinting and wearable hydrogel biosensors are usually reviewed as separate material systems, although both depend on coupled rheology, hydration, transport, mechanics, conductivity, and biointerface stability. This review aims to unify cartilage-oriented hydrogel bioinks and wearable hydrogel sensing interfaces through a quantitative structure–property–function framework. Peer-reviewed studies published mainly from 2019 to 2026 were compared by extracting rheological, swelling, hydration-retention, mechanical, conductive, biocompatibility, and sensing parameters. Printable hydrogel systems showed viscosities of 4.6–264.1 Pa·s, yield stresses of 132–240 Pa, storage moduli from 543 Pa to >5 kPa, swelling ratios of approximately 115–227%, filament diameters of 210–220 μm, printability values of 0.93–0.95, and cell viability of about 90–95% in selected cartilage-oriented constructs. Wearable hydrogel systems showed conductivities from >10−2 S m −1 to >11 S cm −1 , water retention up to 94.4% after 30 days, stretchability up to 719%, motion-artifact reduction by about threefold, and biomarker detection limits of 0.26–0.51 nmol cm −2 for cholesterol and lactate. The main scientific observation is that high-performing hydrogels rarely rely on single-polymer networks; instead, hybrid, nanocomposite, conductive, bioactive, zwitterionic, or multilayer architectures are needed to balance printability, hydration control, mass transport, mechanical robustness, biological safety, and signal reliability. This review differs from previous hydrogel reviews by integrating biofabrication and biosensing metrics into one benchmark map and by translating scattered experimental data into design rules for scalable, reproducible, and multifunctional biomedical hydrogel platforms.
Khoirunnisa et al. (Mon,) studied this question.