Evaluating the Feasibility of Magnetic Tools for the Minimum Dynamic Requirements of Microneurosurgery

Neurosurgery could benefit from robot-assisted minimally invasive approaches, but existing robot tools are insufficiently small and compact. Magnetic actuation is an attractive approach to medical robotics because it allows small, modular serial mechanisms to be remotely actuated. Despite these advantages, magnetic actuation is relatively weak compared to alternative actuation methods. In this paper, we introduce a novel analytical model for magnetic serial robots, use this model to design two prototypes, and then demonstrate that a 4-mm-diameter prototype without any internal mechanical transmission can produce forces up to 0.181 N: high enough to perform delicate microsurgical tasks. We also demonstrate that the robot can achieve a closed-loop step response rise time of 0.71 seconds with an overshoot of 7.8%: sufficiently fast for surgical motions while maintaining a tip precision of less than 2 mm during a worst-case dynamic motion. These experiments provide strong evidence for the feasibility of directly-driven magnetic tools for neurosurgical applications, and they motivate future investigations in this area.