Surgical Robot in MRI

Combining magnetic field immunity with high precision motion over inches of travel, Piezo LEGS® motors walk the line.

Surgeons treating brain cancer face a conundrum: They can capture ultra-high-resolution images of the tumor using magnetic resonance imaging (MRI) or they can use ultra-precise surgical tools to remove the tumor, but they can’t do both at the same time. At least they couldn’t previously. Worcester Polytechnic Institute professor Greg Fischer has developed a surgical robot designed for use inside an MRI machine. Guided by real-time feedback, the robot can position a high-energy, interstitial focused ultrasound probe exactly at the tumor, delivering optimal surgical results and an ideal outcome for the patient.

The powerful magnetic field generated by an MRI machine makes hazards of even small ferromagnetic objects like screws, let alone, motion devices like permanent magnet motors, gearboxes, and actuators. It was obvious from the outset that the MRI robot had to be based on non-traditional actuation. The answer proved to be a piezoelectric device. Of course, building a robot that can operate within the high magnetic fields generated by an MRI unit was not easy, but with sophisticated controls engineering and piezoelectric positioners from PiezoMotor, the WPI team has built a system that promises to revolutionize the treatment possibilities of MRI.

To provide positioning capabilities in a high magnetic field, the WPI group used piezoelectric motors from PiezoMotor. Because the units came as fully functioning packages, the team could focus on the larger challenges of the project rather than building a motor. “The ability to just put them in and have them work has been really, really nice,” says Fischer.


  • Video: Guiding Surgical Robots with MRI Images

    Greg Fischer, assistant professor of mechanical engineering, is developing robotic systems that will allow surgeons to operate with the guidance of real-time MRI (magnetic resonance imaging) images. The interior of an MRI scanner, which uses strong magnets and radio waves, is a difficult environment for robots.

Piezo LEGS® non-magnetic solution

  • Completely non-magnetic
  • Motors designed and priced for integration in OEM equipment
  • Self-locking with high holding force
  • No mechanical play or backlash