A novel Microchannel Electrode Array: Towards bioelectronic medical interfacing of small peripheral nerves

Abstract

Bioelectronic medicine is an emerging field that relies on electrical signals to modulate complex neuronal circuits, particularly in the peripheral nervous system, as an alternative to drug-enabled therapeutics. Small autonomic nerves are one of the targets in this field, however, interfacing peripheral nerves smaller than 300 μm remains a challenge. Here we report the development of a Microchannel Electrode Array (DCEA) capable of interfacing nerve fascicles as small as 50-300μm. The current μCEA records and stimulates from 28 channels and is designed for easy implantation and removal, bearing promise to enable neural interfacing in BM.

Microchannel Electrode Stimulation of Deep Peroneal Nerve Fascicles Induced Mean Arterial Depressor Response in Hypertensive Rats

“…We hypothesized that electrical stimulation of a fascicle of the somatic deep peroneal nerve (fDPN) provides an effective substrate to induce a significant depressor response in HTN with minimal side effects. A microchannel electrode array (μCEA) specifically designed and fabricated for interfacing with small nerves (that is, 50-300 μm in diameter; autonomic nerve or nerve fascicles) was used to stimulate the fDPN (~150 μm in diameter) (15). We demonstrate that a significant reduction in mean arterial pressure (MAP) in hypertensive rats can be achieved through microelectrical stimulation of a somatic nerve fascicle for up to 4 h without significantly altering HR.…”

“…We have previously developed a μCEA to facilitate the interface with small diameter nerves (50-300 μm) with minimal impact on the nerve during implantation. The μCEA electrode was fabricated and characterized as reported previously (15). Briefly, silicon dyes were stacked to form a 2-mm microchannel (that is, 200 μm wide), where 15 gold square electrodes (40 × 50 μm; approximately 2,000 μm 2 ) were placed bilaterally on the sidewalls (100 μm tall; Figure 1A).…”

“…These dimen- sions were optimized for reading the neural output of a small diameter nerve in a rat. The μCEA was coupled to an Omnetics connector by using sonically bonded Parylene-C insulated 25-μm gold wires and further insulated with epoxy (15). Impedance spectroscopy showed values <500 kΩ in at least 50% of the electrodes.…”

Renal Nerve Activity and Arterial Depressor Responses Induced by Neuromodulation of the Deep Peroneal Nerve in Spontaneously Hypertensive Rats

“…Alternative treatments include electroacupuncture based either on Qi hypotheses or mechanistic information, where controlled clinical trials have shown a significantly lower 24-h ambulatory MAP ( > 6 mmHg), correlated with reductions in circulating norepinephrine, renin, and aldosterone ( Flachskampf et al, 2007 ; Li et al, 2015 ). We previously reported that stimulation of the deep peroneal nerve (DPNS), a fascicle of the sciatic nerve in proximity to the acupuncture point ST-36, induced a 23 mmHg reduction in MAP in anesthetized spontaneously hypertensive rats (SHRs) ( Kim and Romero-Ortega, 2012 ; Kim et al, 2014 ). However, confirming the depressor effect in freely moving animals who underwent DPNS has remained a challenge, given the small size of the rat peroneal nerve (≈200 μm OD) and the need for fully implantable miniature wireless stimulators to avoid nerve injury and/or discomfort to the animal during ambulation.…”