Magnetic oxygen-generating robots via a self-healing hydrogel-based modular assembly strategy

Magnetically driven hydrogel robots exhibit significant potential in biomedical and underwater applications owing to their remote controllability, flexibility, biocompatibility, and chemical stability. However, the lack of functional integration in existing hydrogel robots limits their adaptability to diverse applications. In this work, a novel universal strategy for modular assembly of hydrogels has been introduced, which involves the incorporation of magnetic particles within a self-healing κ-carrageenan/polyacrylamide-based hydrogel, facilitating the free assembly of magnetic actuation modules. These modules can construct magnetic soft robots characterized by complex geometries and magnetization distributions, allowing for diverse deformations under magnetic fields. Furthermore, this strategy enables the integration of additional functionalities, such as photocatalysis. The free assembly of functional modules embedded with specifically designed photocatalysts (e.g., Ru-Bi2CrO6) and magnetic actuation modules results in an oxygen-generating robot. The robot demonstrates flexible underwater movement through magnetically controlled oscillatory actuation, effectively reducing water agitation while providing a stable oxygen supply to specific aquatic environments via photocatalytic oxygen generation, achieving an oxygen evolution rate of 389.1 μmol g−1 h−1. The hydrogel skeleton of the oxygen-generating robot effectively suppresses photocatalytic particle aggregation and sedimentation, while enabling facile magnetic recovery. This innovative method provides a scalable and adaptable approach to the design and multifunctional integration of soft robots.