A comparative study assessing neural recording quality and inflammatory tissue response between stiff and flexible...

Area of Science:

• Neuroscience
• Biomaterials Science
• Medical Devices

Background:

• Implantable microelectrode arrays (MEAs) are crucial for neurophysiology and neuroprosthetics.
• Long-term efficacy of MEAs is limited by the brain's inflammatory response to implanted devices.

Purpose of the Study:

• To investigate how the substrate rigidity of MEAs affects neural recording quality.
• To evaluate the impact of MEA substrate rigidity on inflammatory tissue responses in deep brain regions.

Main Methods:

• Implantation of stiff silicon-based and flexible polyimide-based MEAs in the mouse striatum.
• Weekly electrophysiological and impedance measurements over four weeks.
• Histological analysis of glial scarring, blood-brain barrier integrity, and neuronal populations.

Main Results:

• Flexible MEAs maintained stable recording quality (signal-to-noise ratio, unit yield, amplitude) over time.
• Stiff MEAs showed performance deterioration, increased glial scarring (Iba-1, GFAP), and blood-brain barrier leakage (IgG).
• Higher Piezo1 expression was observed around stiff MEAs, correlating with inflammation markers.

Conclusions:

• Flexible MEA substrates promote better device-tissue integration, leading to reduced inflammation and improved chronic recording stability.
• Substrate rigidity is a critical design factor influencing adverse tissue reactions to deep brain implants.
• Findings guide the development of more reliable neural interface devices.