Recording properties and biocompatibility of chronically implanted polymer-based intrafascicular electrodes

Area of Science:

• Neuroscience
• Biomaterials Science
• Medical Devices

Background:

• Developing effective neural interfaces is crucial for restoring function after neurological injury.
• Polymer-based longitudinal intrafascicular electrodes (polyLIFEs) are a promising technology for neural recording.

Purpose of the Study:

• To evaluate the electrical properties and biocompatibility of polyLIFEs implanted in feline dorsal rootlets.
• To assess the long-term effects of polyLIFEs and their associated cuffs on neural tissue.

Main Methods:

• Implantation of polyLIFEs in feline dorsal rootlets for acute and chronic periods (2-6 months).
• Analysis of 38 implanted electrodes, with 25 utilizing an insulative flexible polymer cuff.
• Measurement of axon distributions at various levels relative to the implant and in control tissues.
• Evaluation of electrode impedance and histological assessment of neural tissue.

Main Results:

• Electrode impedances remained stable throughout the experimental duration.
• PolyLIFEs demonstrated high biocompatibility, with no observed adverse effects on axon size in implanted or neighboring neural tissue.
• Insulative cuffs caused significant neural tissue compression, leading to localized necrosis.

Conclusions:

• PolyLIFEs exhibit favorable electrical stability and biocompatibility for neural recording applications.
• The use of insulative cuffs with polyLIFEs presents a significant challenge due to induced neural tissue compression and necrosis.
• Further design modifications are needed to mitigate compression effects for safe and effective long-term neural implantation.