Wearable Sensors Fabricated by 3D-Printed Composite Hydrogel with 2D Fillers

Flexible sensors demonstrate exceptional adaptability across human-computer interaction, health monitoring, and robotic systems. However, sensing materials suffer from inadequate conformation capability and microstructural inaccuracies, resulting in function deficiencies. This review examines composite hydrogel formulations that incorporate conductive nanofillers, with particular emphasis on 2D nanomaterials, whose functional tunability enables precise regulation of electrical and interfacial properties. The strategic integration of microstructures further improves sensor sensitivity, durability, and environmental adaptability. We also examine implementation of flexible sensors based on 3D-printed hydrogel in emerging applications including pH monitoring, glucose detection, and food safety assessment. We suggest that future development prioritize elucidating sensing mechanisms, achieving multifunctional integration, advancing material engineering, and refining precision manufacturing. Particularly promising research directions include developing intelligent tactile feedback systems for humanoid robots and creating capsule robot-integrated platforms for gastrointestinal disease monitoring.