MINRob: A Large Force-Outputting Miniature Robot Based on a Triple-Magnet System

Magnetically actuated miniature robots are limited in their mechanical outputting capability, because the magnetic forces decrease significantly with decreasing robot size and increasing actuating distance. Hence, the output force of these robots can hardly meet the demand for specific biomedical applications (e.g., tissue penetration). This article proposes a tetherless magnetic impact needle robot (MINRob) based on a triple-magnet system with reversible and repeatable magnetic collisions to overcome this constraint on output force. The working procedure of the proposed system is divided into several states, and a mathematical model is developed to predict and optimize the force output. These force values in magnetic impact and penetration are obtained from a customized setup, indicating a ten-fold increase compared with existing miniature robots that only utilize magnetic attractive force. Eventually, the proposed MINRob is integrated with a teleoperation system, enabling remote and precise control of the robot's position and orientation. The triple-magnet system offers promising locomotion patterns and penetration capacity via the notably increased force output, showing great potential in robot-assisted tissue penetration in minimally invasive healthcare.