MRI-compatible micromanipulator; design and implementation and MRI-compatibility tests.

In this paper, we present a magnetic resonance imaging (MRI)-compatible micromanipulator, which can be employed to provide medical and biological scientists with the ability to concurrently manipulate and observe micron-scale objects inside an MRI gantry. The micromanipulator formed a two-finger micro hand, and it could handle a micron-scale object using a chopstick motion. For performing operations inside the MRI gantry in a manner such that the MRI is not disturbed, the system was designed to be nonmagnetic and electromagnetically compatible with the MRI. The micro-manipulator was implemented with piezoelectric transducers (PZT) as actuators for micro-motion, strain gauges as sensors for closed-loop control, and a flexure parallel mechanism made of acrylic plastic. Its compatibility with a 2-Tesla MRI was preliminarily tested by checking if the MRI obtained with the micromanipulator were similar to those obtained without the micromanipulator. The tests concluded that the micromanipulator caused no distortion but small artifacts on the MRI. The signal-to-noise ratio (SNR) of the MRI significantly deteriorated mainly due to the wiring of the micromanipulator. The MRI caused noise of the order of ones of volts in the strain amplifier.