Surface-Grafted Biocompatible Polymer Conductors for Stable and Compliant Electrodes for Brain Interfaces

Area of Science:

• Bioelectronics
• Materials Science
• Neuroscience

Background:

• Chronic neural implants require durable, conductive interfaces for high-resolution recording.
• Existing conductive polymer coatings face challenges with long-term stability and potential property degradation due to crosslinking.

Purpose of the Study:

• To develop a stable and highly conductive polymer coating for neural electrodes.
• To improve the durability and performance of chronic neural implants.

Main Methods:

• Grafting of a poly(3,4 ethylenedioxythiophene) scaffold with a poly(styrenesulfonate)-b-poly(poly(ethylene glycol) methyl ether methacrylate) block copolymer brush onto gold surfaces.
• Utilizing surface-initiated atom-transfer radical polymerization (SI-ATRP) for controlled polymer brush synthesis.

Main Results:

• The "block-brush" coating demonstrated high volumetric capacitance (120 F cm⁻³).
• Achieved strong adhesion to the metal substrate, surviving 4 hours of ultrasonication.
• Exhibited improved surface hydrophilicity and enhanced stability against 10,000 charge-discharge voltage sweeps.
• Showed a 33% improvement in stability against current pulsing.

Conclusions:

• The developed block-brush polymer coating offers a stable, conductive, and durable interface for neural recording.
• This approach provides a tunable platform for advanced bioelectronic applications.
• The findings pave the way for improved neural implants in neurodegenerative disorder research and treatment.