Graphene Encapsulated Copper Microwires as Highly MRI Compatible Neural Electrodes

Area of Science:

• Neuroscience
• Biomaterials Engineering
• Medical Imaging

Background:

• Combining electrophysiology and Magnetic Resonance Imaging (MRI) offers comprehensive brain activity mapping.
• Copper is MRI-compatible due to its magnetic susceptibility but is cytotoxic for direct implantation.
• Existing neural electrodes face limitations in simultaneous high-resolution electrophysiological recording and MRI.

Purpose of the Study:

• To develop a novel neural electrode overcoming copper's cytotoxicity for combined MRI and electrophysiological recordings.
• To evaluate the biocompatibility and MRI compatibility of the new microelectrode design.
• To demonstrate the utility of the microelectrodes for in vivo neural signal acquisition.

Main Methods:

• Fabrication of graphene encapsulated copper (G-Cu) microelectrodes.
• In vitro cytotoxicity testing and in vivo histological analysis.
• Electrophysiological recordings (local field potentials and single-unit spikes) in rodent brains.
• Assessment of MRI compatibility using a 7.0 T MRI scanner.

Main Results:

• Graphene encapsulation significantly reduced copper's cytotoxicity in vitro and in vivo.
• G-Cu microelectrodes successfully recorded neural signals, including local field potentials and single-unit spikes.
• The G-Cu microelectrodes exhibited no significant image artifacts in high-field MRI, indicating excellent compatibility.

Conclusions:

• Graphene encapsulation effectively mitigates copper cytotoxicity, creating a biocompatible neural electrode.
• The G-Cu microelectrodes are highly compatible with MRI, enabling artifact-free simultaneous recordings.
• These G-Cu probes represent a significant advancement for combined electrophysiology and MRI applications in neuroscience and clinical settings.