Microneedle Penetrating Array with Axon-Sized Dimensions for Cuff-less Peripheral Nerve Interfacing.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Autonomic nerves, crucial for sympathetic and parasympathetic control, are typically only hundreds of microns in diameter near organ targets.
• Existing methods for interfacing with small nerves often involve bulky cuffs, limiting precision and potentially causing damage.

Purpose of the Study:

• To design and fabricate an ultra-miniaturized, cuff-less microneedle array for mapping small autonomic nerves.
• To develop a novel surgical technique for secure, non-cuff implantation of the microneedle array.

Main Methods:

• Fabrication of high-density silicon microneedle arrays (25-100 needles) on a silicone substrate, featuring 1-micron tips and dual-taper shafts.
• Control over needle tip and shaft angles for optimized sharpness and stiffness.
• Development of a surgical technique using photochemical bonding of collagen/Rose Bengal adhesive to epineurium for cuff-less array fixation.

Main Results:

• Demonstrated arrays with controllable needle geometry and a backside anchor for stability on elastic substrates.
• Successfully fabricated arrays capable of wrapping around a 300-μm nerve.
• Presented a viable surgical method for implanting arrays as small as 0.3 mm x 1.2 mm without a cuff.

Conclusions:

• The developed ultra-miniaturized microneedle array and surgical technique show promise for precise mapping of small autonomic nerves.
• This cuff-less approach offers a potential advancement over traditional nerve interfacing methods.
• Future research will involve device functionalization and validation in a rat vagus nerve model.