Design of an MRI compatible haptic interface

This paper proposes an MRI-compatible, 1-axis force sensing unit which is designed to be used as a haptic interface on an MRI compatible robot. Recently, it became a popular research direction to enable MRI in surgical operations and brain studies with the help of robotic devices. However, due to high magnetic field in MRI environment, conventional sensors and robots cannot be used in MRI rooms. Existing MRI-compatible force sensors have limited number of degrees of freedom or they do not offer compact solutions for multiple-axis sensing. In this paper, a compact 1-axis force sensing unit which employs a compliant displacement amplification mechanism is introduced and then analyzed for better sensitivity and accuracy. A combination of multiple proposed sensing units can be assembled to have a force sensor with desired number of degrees of freedom. Prototypes made of delrin and ABS-plastic are tested. Experiments indicated that the proposed sensor is suitable for force sensing and fully compatible to MRI. Also, the sensor made of delrin is superior in mechanical performance and MRI compatibility to ABS-plastic sample.