Magnetic Fluid-Driven Vine Robots for Minimally Invasive Tissue Biopsy Sampling

There is a growing need for precise, minimally invasive biopsy techniques that reduce patient discomfort, improve sampling accuracy in hard-to-reach areas, and minimize tissue damage. Vine robots, a type of continuum robot, offer a promising solution with their unique ability to evert, allowing them to navigate complex environments while reducing friction. This article presents a novel vine robot design powered by magnetic fluid. The fluid drives both vine growth through pressurization and enables precise steering and manipulation using external magnetic fields. Unlike previous designs, the robot's high magnetic volume ensures precise control even under pressure, while maintaining a fully soft structure. This allows for controlled needle movements during biopsies. Additionally, the robot achieves passive stabilization by pressing against surrounding walls. This stabilization, combined with magnetic forces, can exert up to 1.26 N of insertion force at the tip, enabling effective tissue penetration. Experiments are conducted with a 5 mm diameter, 145 mm long magnetic fluid-driven vine robot, demonstrating movement in free space, through narrow constrictions, and within phantoms modeled after human bronchial anatomy. These results pave the way for the robot's potential application in minimally invasive surgeries, particularly in difficult-to-access areas of the body.