Objective. Previous animal studies have demonstrated that carbon nanotube (CNT) electrodes provide several advantages of preferential cell growth and better signal-to-noise ratio (SNR) when interfacing with brain neural tissue. This work explores another advantage of CNT electrodes, namely their MRI compatibility. MRI-compatible neural electrodes that do not produce image artifacts will allow simultaneous co-located functional MRI and neural signal recordings, which will help improve our understanding of the brain. Approach. Prototype CNT electrodes on polyimide substrates are fabricated and tested in vitro and in vivo in rat brain at 9.4 T. To understand the results of the in vitro and in vivo studies, a simulation model based on numerical computation of the magnetic field around a two-dimensional object in a tissue substrate is developed. Main Results. The prototype electrodes are found to introduce negligible image artifacts in structural and functional imaging sequences in vitro and in vivo. Simulation results confirm that CNT prototype electrodes produce less magnetic field distortion than traditional metallic electrodes due to a combination of both superior material properties and geometry. By using CNT films, image artifacts can be nearly eliminated at magnetic fields of strength up to 9.4 T. At the same time, the high surface area of a CNT film provides high charge transfer and enables neural local field potential recordings with an equal or better SNR than traditional electrodes. Significance. CNT film electrodes can be used for simultaneous MRI and electrophysiology in animal models to investigate fundamental neuroscience questions and clinically relevant topics such as epilepsy.
Bibliographical noteFunding Information:
This work was supported in part by an Institute for Engineering in Medicine (IEM) Group Grant at the University of Minnesota, the University of Minnesota MnDrive RSAM Initiative Grant, the Minnesota Supercomputing Institute (MSI) at the University of Minnesota, NIH grants R01 MH111413 01, R01 NS057560, R01 NS070839, R24 MH106049, P41 EB015894, P30 NS076408, the W M Keck Foundation, and NSF-IGERT DGE-1069104.
- carbon nanotubes
- functional magnetic resonance imaging
- magnetic susceptibility