Miniature soft robots have evolved into various therapeutic applications due to good adaptability. Nonetheless, complex terrains inside body, especially soft wrinkled topography with non-Newtonian viscous mucus in the gastrointestinal tract, pose a strict demand on the navigation of such robots. To address the challenge, here a design inspiration derived from sea urchin is proposed to fabricate the soft-cone-assisted rolling robot (SCARBot) by encapsulating blood coagulation gel, creating a hollow cylindrical structure for loading drugs inside. The arrangement of an array of soft cones with manually designed hydrophobicity allows for controlled locomotion of the robots under low-frequency magnetic field, significantly reducing surface friction and improving environmental adaptability. This motion ability is further supported by US-imaging-guided navigation in an ex vivo and even in vivo gastrointestinal tract. When the high-frequency magnetic field is exerted, the drug-loaded blood coagulation gel sealed inside the robot melts by magnetothermal effect, thereby releasing drugs at the targeted location. The synergy of magnetothermal and pharmacological therapy enable this robot to exhibit enhanced antibacterial efficiency for ex vivo and in vivo bacterial infection and inflammation. Such soft robots with exceptional adaptability and therapeutic functions offer high potential for targeted delivery and therapy through lumens inside body.

Untethered and self-transformable miniature robots are capable of performing reconfigurable deformation and on-demand locomotion, which aid the traversal toward various lumens, and bring revolutionary changes for targeted delivery in gastrointestinal (GI) tract. However, the viscous non-Newtonian liquid environment and plicae gastricae obstacles severely hamper high-precision actuation and payload delivery. Here, we developed a low-friction soft robot by assembly of densely arranged cone structures and grafting of hydrophobic monolayers. The magnetic orientation encoded robot can move in multiple modes, with a substantially reduced drag, terrain adaptability, and improved motion velocity across the non-Newtonian liquids. Notably, the robot stiffness can be reversibly controlled with magnetically induced hardening, enabling on-site scratching and destruction of antibiotic-ineradicable polymeric matrix in biofilms with a low-frequency magnetic field. Furthermore, the magnetocaloric effect can be utilized to eradicate the bacteria by magnetocaloric effect under high-frequency alternating field. To verify the potential applications inside the body, the clinical imaging-guided actuation platforms were developed for vision-based control and delivery of the robots. The developed low-friction robots and clinical imaging-guided actuation platforms show their high potential to perform bacterial infection therapy in various lumens inside the body.