Electrode sharpness and insertion speed reduce tissue damage near high-density penetrating arrays

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Neural electrodes are vital for interfacing biological tissues with electronic devices.
• Implanting high-density microwire arrays presents challenges like tissue dimpling and the 'bed-of-nails' effect.
• Minimizing tissue disruption during electrode implantation is critical for device efficacy and longevity.

Purpose of the Study:

• To determine the optimal tip profile and insertion speed for Paradromics' fine microwire arrays (FμA) in rodent primary visual cortex (V1).
• To assess the impact of electrode implantation on the blood-brain barrier (BBB) and cellular damage.
• To identify insertion strategies that minimize tissue disruption.

Main Methods:

• Evaluated tissue response, including BBB integrity and cellular damage, to different electrode tip profiles (electro-sharpened, blunt, angled).
• Investigated the effect of insertion speeds (slow, fast, pneumatic) on tissue compromise.
• Performed histological analysis and single-unit recordings to validate electrode performance.

Main Results:

• Electro-sharpened arrays caused significantly less cellular damage near the tip compared to blunt or angled arrays.
• Slow insertion speeds resulted in greater BBB compromise than fast or pneumatic methods.
• Optimized electro-sharpened arrays successfully captured neural activity, validating their efficacy.

Conclusions:

• Tailored insertion strategies, particularly using electro-sharpened arrays and faster insertion, are crucial for minimizing tissue damage during neural electrode implantation.
• These optimized arrays are suitable for long-term implant applications, reducing reactive gliosis.
• The study provides foundational insights for developing advanced neural recording devices with improved performance and integration.