Graphene-Based Microelectrodes with Reinforced Interfaces and Tunable Porous Structures for Improved Neural...

Area of Science:

• Biomaterials Science
• Neuroscience
• Materials Engineering

Background:

• Minimizing inflammatory responses in invasive neural implants is crucial for longevity.
• Graphene microfibers offer a high electrochemical surface area (ESA)/geometrical surface area (GSA) ratio, suggesting potential for low impedance and high charge injection capacity (CIC).
• Precise control over graphene's porous structure is key to optimizing its electrochemical performance but remains under-investigated.

Purpose of the Study:

• To develop and characterize wet-spun graphene-based electrodes with tunable porous structures.
• To optimize the electrochemical properties of reduced graphene oxide (rGO) by controlling pore size through sucrose concentration.
• To evaluate the performance of these novel electrodes for neural recording and stimulation compared to conventional platinum microwires.

Main Methods:

• Graphene-based electrodes were fabricated using a wet-spinning technique.
• Pore structure was tuned by varying sucrose concentrations in the coagulation bath.
• Electrochemical properties (impedance, CIC, charge storage capacity - CSC) were measured.
• Mechanical properties were assessed through tensile and insertion tests.
• In vivo acute recordings from the auditory cortex and ex vivo recordings from hippocampal slices were performed.

Main Results:

• Optimized rGO/sucrose ratios significantly reduced impedance and increased CIC and CSC compared to platinum microwires.
• Electrodes exhibited sufficient tensile strength for 100% insertion success with minimal angle shift.
• In vivo recordings showed improved signal-to-noise ratio (SNR) due to lower impedance.
• Ex vivo recordings demonstrated high-fidelity neural recording and stimulation capabilities.

Conclusions:

• Wet-spun graphene electrodes with controlled porosity offer superior electrochemical performance over platinum microwires.
• These graphene electrodes are mechanically robust for precise implantation.
• They show significant promise for advanced neural interfaces, improving both implant longevity and signal quality.