Pressure-free growing robots for soft medical robotics

Researchers at the University of Leeds and the University of California San Diego received RoboSoft’s Best Paper Award for a 1.8 mm-diameter soft growing robot intended for minimally invasive medical robotics. Unlike conventional tools that push their bodies through tissue, the vine-inspired device extends at its tip, leaving deployed sections largely stationary. This may reduce friction, irritation, and inflammation along an insertion path while allowing the compliant body to deform around obstacles and follow lower-resistance routes.

The robot grows without internal air pressure, avoiding the risk of air leakage in fluid-filled spaces near the spine or in blood vessels. Eliminating pressure also allows growth and magnetic steering to occur simultaneously, rather than in alternating steps used by earlier prototypes. Its silicone body contains magnetic particles that are molded and magnetized in controlled patterns. External magnetic fields then produce predictable bending, while motion of the magnetized regions supports real-time shape estimation at up to 500 Hz.

The team integrated actuation and sensing in the same miniaturized structure instead of placing separate components along the body. Manufacturing required careful injection molding, vacuum processing, particle distribution, and defect prevention because the catheter wall is about 100 microns thick. The researchers also optimized magnetic patterns to prevent attraction between the robot’s inner and outer layers, which could raise friction.

In an ex vivo stomach model, the device demonstrated retroflexion and biome sampling, showing difficult-angle access and precise tool positioning in realistic anatomy. The researchers are interested in neural and spinal uses, including electrode placement after injury, but describe the technology as early stage. Their near-term goals are pre-clinical safety, biocompatibility, and in-vivo demonstrations before potential clinical use.