Ultra-nanocrystalline diamond electrodes: optimization towards neural stimulation applications

Area of Science:

• Biomaterials Science
• Neurotechnology
• Electrochemistry

Background:

• Diamond offers excellent biocompatibility and biostability for biomedical implants.
• Previous research reported low electrochemical double layer capacitance, limiting diamond's use in neural stimulation electrodes.
• Conducting diamond's potential in neural interfaces remained largely untapped due to electrochemical limitations.

Purpose of the Study:

• To electrochemically characterize nitrogen-doped ultrananocrystalline diamond (N-UNCD) for neural stimulation applications.
• To investigate methods for enhancing the charge injection capacity of N-UNCD electrodes.
• To assess the feasibility of N-UNCD in fabricating advanced, bio-permanent neural stimulation devices.

Main Methods:

• Electrochemical characterization of N-UNCD electrodes.
• Tailoring N-UNCD growth conditions to optimize performance.
• Post-growth electrochemical activation and metalization (platinum, iridium) of N-UNCD electrodes.

Main Results:

• N-UNCD electrodes demonstrated high charge injection capacity, reaching up to 163 µC cm⁻².
• Charge injection capacity was significantly increased by optimizing growth conditions and electrochemical activation.
• Metalization with platinum or iridium further boosted charge injection capacity, confirming N-UNCD's viability.

Conclusions:

• N-UNCD is a promising material for fabricating neural stimulation microelectrodes.
• Optimized and metalized N-UNCD electrodes offer enhanced performance for neural interfaces.
• This advancement enables the development of physically stable, hermetic, long-term implantable bionic devices.