Magnetic resonance compatibility of multichannel silicon microelectrode systems for neural recording and stimulation: design criteria, tests, and recommendations

Magnetic resonance (MR) compatibility of biomedical implants and devices represents a challenge for designers and potential risks for users. This paper addresses these problems and presents the first MR-compatible multichannel silicon chronic microelectrode system, used for recording and electrical stimulation of the central nervous system for animal models. A standard chronic assembly, from the Center for Neural Communication Technology at the University of Michigan, was tested on a 2 Tesla magnet to detect forces, heating, and image distortions, and modified to minimize or eliminate susceptibility artifacts, tissue damage, and electrode displacement, maintaining good image quality and safety to the animals. Multiple commercial connectors were tested for MR compatibility and several options for the reference electrode were also tested to minimize image artifacts and provide a stable biocompatible reference for short- and long-term neural recordings. Different holding screws were tested to anchor the microelectrode assembly on the top of the skull. The final selection of this part was based on MR-compatibility, biocompatibility, durability, and mechanical and chemical stability. The required adaptor to interconnect the MR-compatible microelectrode with standard data acquisition systems was also designed and fabricated. The final design is fully MR-compatible and has been successfully tested on guinea pigs.