Non-metallic and low-friction linear bearings for MRI scanners

This robot was developed for feed-through interventional focussed ultrasound (FUS) on a child's brain. This procedure can be used for the non-invasive treatment of epilepsy and stroke in children without the need to make an incision in the patient's skull. This allows for a less harmful procedure and faster recovery compared to traditional brain surgery, where the patient's skull and brain need to be opened. The robot is a manipulator with five degrees of freedom that works inside a magnetic resonance imaging (MRI) machine. Bearings, threaded spindles and lead screw nuts must be used on each axis of this machine, whereby there are linear and rotary axes. As the robot has to work in the strong magnetic field of the MRI machine, metal bearings cannot be used here.

Today, iglidur® plastic bearings are used in the robot instead of metal bearings. The high-performance iglidur®-plastic enable the device to work in the difficult environment without interacting with the magnetic field.
They drive the translation axes and rotation axes of the robot. In addition, threaded spindles and lead screw nuts from the drylin® portfolio as well as drylin® SLW linear stages and easytube linear units are sometimes used. The bearing components are also used in the application to generate a smooth and low-friction shaft rotation to drive the robot's joints. This is because the MRT-compatible motors used developed a relatively low torque, which also generated friction when driving the heavy payload.