Biodegradable Magnetic Hydrogel Robot with Multimodal Locomotion for Targeted Cargo Delivery

Recent strides in the development of untethered miniaturerobotshave shown the advantages of diverse actuation methods, flexible maneuverability,and precise locomotion control, which has made miniature robots attractivefor biomedical applications such as drug delivery, minimally invasivesurgery, and disease diagnosis. However, biocompatibility and environmentaladaptability are among the challenges for further in vivo applicationsof miniature robots due to the sophisticated physiological environment.Herein, we propose a biodegradable magnetic hydrogel robot (BMHR)that possesses precise locomotion with four stable motion modes, namelytumbling mode, precession mode, spinning-XY mode, and spinning-Z mode.Using a homemade vision-guided magnetic driving system, the BMHR canachieve flexible conversion between the different motion modes tocope with changes in complex environments, and its superior abilityto cross obstacles is demonstrated. In addition, the transformationmechanism between different motion modes is analyzed and simulated.Benefiting from the diverse motion modes, the proposed BMHR has promisingapplications in drug delivery, showing remarkable effectiveness intargeted cargo delivery. The BMHR's biocompatible property,multimodal locomotion, and functionality with drug-loaded particlescan provide a new perspective to combine miniature robots with biomedicalapplications.