Design and compatibility of a high-performance actuation system for fMRI-based neuroscience studies

Haptic interfaces compatible with functional magnetic resonance imaging (fMRI) are finding increasing interest as a tool to explore the neural correlates of human motor control and related dysfunctions. To achieve safety and MR compatibility, such devices have mainly relied on unconventional actuation methods suffering from limited bandwidth and non-linearities. This has resulted in complex control and restricted their use in applications involving fine and dynamic interaction with the hand and fingers. To address these limitations, we propose a concept for a shielded high-performance actuation system to be located inside the MR room, evaluate the effectiveness of the shielding and perform detailed MR compatibility tests. A conventional electromagnetic actuator is located within a steel shield to prevent mutual disturbance with magnetic fields of the scanner, which, together with power and control hardware, is placed within a Faraday cage with only a fiber-optical USB link to the control room. Detailed compatibility tests show that disturbing dynamic electromagnetic fields generated by the actuation system are well below the detectable threshold of the scanner, and actuator performance is not degraded by the MR environment. In combination with a light and stiff cable or rod transmission, the presented actuator technology, providing high transparency and force bandwidth, paves the way for fMRI-based neuroscience studies, e.g., to investigate the fine motor control of hand and fingers.