Edge-Functionalized Graphene/Polydimethylsiloxane Composite Films for Flexible Neural Cuff Electrodes

Area of Science:

• Biomaterials Engineering
• Neuroscience
• Materials Science

Background:

• Neural electrode design is evolving with new materials offering adaptable mechanical and electrical properties.
• Polydimethylsiloxane (PDMS) and graphene are key materials in developing advanced neural implants.

Purpose of the Study:

• To investigate the mechanical and electrochemical properties of an edge-functionalized graphene (EFG)/PDMS composite.
• To demonstrate the potential of this composite for neural implants by fabricating a novel neural cuff electrode.

Main Methods:

• Fabrication and mechanical testing of EFG/PDMS composite films (200 μm thick, 1:1 ratio).
• Electrochemical characterization including capacitance, electrochemical water window, and charge injection capacity measurements.
• Biocompatibility assessment using in vitro cell culture with mouse spinal cord cells.
• Fabrication and testing of a novel double-layered, open-structured neural cuff electrode.

Main Results:

• The EFG/PDMS composite film exhibited 20% stretchability, 2.52 MPa Young's modulus, and >10,000 cycle lifetime.
• Electrochemical reduction increased composite capacitance up to 35-fold and charge injection capacity 3-fold, exceeding commercial platinum cuffs.
• The novel neural cuff electrode achieved 140% stretchability, demonstrating enhanced integration and usability.

Conclusions:

• The EFG/PDMS composite possesses suitable mechanical and electrochemical properties for neural interfacing.
• Electrochemical activation enhances charge injection capacity via stable hydrogen chemisorption.
• The novel neural cuff design shows significant improvements in stretchability and tissue integration for neural implants.