Multi-channel intraneural vagus nerve recordings with a novel high-density carbon fiber microelectrode array

Abstract

25Autonomic nerves convey essential neural signals that regulate vital body functions. Recording 26 clearly distinctive physiological neural signals from autonomic nerves will help develop new 27 treatments for restoring regulatory functions. However, this is very challenging due to the small 28 nature of autonomic nerves and the low-amplitude signals from their small axons. We developed 29 a multi-channel, high-density, intraneural carbon fiber microelectrode array (CFMA) with ultra-30 small electrodes (8-9 µm in diameter, 150-250 µm in length) for recording physiological action 31 potentials from small autonomic nerves. In this study, we inserted CFMA with up to 16 32 recording carbon fibers in the cervical vagus nerve of 22 isoflurane-anesthetized rats. We 33 recorded action potentials with peak-to-peak amplitudes of 15.1-91.7 µV and signal-to-noise 34 ratios of 2.0-8.3 on multiple carbon fibers per experiment, determined conduction velocities of 35 some vagal signals in the afferent (0.7-1.0 m/sec) and efferent (0.7-8.8 m/sec) directions, and 36 monitored firing rate changes in breathing and blood glucose modulated conditions. Overall, 37 these experiments demonstrated that CFMAs are a novel interface for in-vivo intraneural action 38 potential recordings from autonomic nerves. This work is a milestone towards the 39 comprehensive understanding of physiological neural signaling and the development of 40 innovative treatment modalities for restoring vital functions controlled by autonomic nerves. 41 42

Ultra-flexible and Stretchable Intrafascicular Peripheral Nerve Recording Device with Axon-dimension, Cuff-less Microneedle Electrode Array

“…However, we were unable to confirm if all spikes on a given channel were from a single or multiple axons due to similarity in spike waveform shapes and normal variations in amplitude. The observation of one unit typically sorted per electrode in a nerve fascicle is consistent with prior studies of microelectrode interfacing with peripheral nerves [8,38] . Intraneural recordings from peripheral nerves, such as shown here, may have significant utility in studying organ and limb neurophysiology and in providing sensory feedback for neuroprostheses.…”

“…The development of intrafascicular devices enabled researchers to detect and modulate neural activities at a higher resolution. To date, a variety of intrafascicular recording and/or stimulation methods have been achieved using thin-film polymer devices [6,7] , carbon fiber electrode arrays [8,9] , highly conductive carbon-based threads with low electrochemical impedance [10][11][12] , Utah arrays [13,14] , flexible microneedle electrode arrays [15][16][17] and regenerative devices [18] . With implantation of such devices, researchers were able to map and decode motor and/or sensory somatic or autonomic systems at a sub-fascicular level [19,20] .…”

Sharpened and mechanically durable carbon fiber electrode arrays for neural interfacing

“…Six Flex Arrays with SCFs of 200-250 µm length, as represented in Figure 1C, were inserted into the left CVN of 22 Sprague-Dawley rats ( Figure 5E, Supplemental Video 3). Detailed characterization of the population recordings is presented in a companion study by Jiman et al 2020. In all experiments, we visually observed successful insertion of all SCFs into the vagus nerve after an average of 2.3 insertion attempts. The functional SCFs Figure 5.…”

“…We observed that 19.8% of functional SCFs recorded neural clusters with SNRs > 4. The maximum mean Vpp was found to be 91.72 µV (Jiman et al, 2020).…”

“…The functional SCFs Figure 5. Neural activity recorded from a rat cervical vagus nerve (CVN) with sharpened carbon fibers (SCFs) on a Flex Array, representative of the larger data set shown in Jiman et al, 2020. A and C) Three seconds of filtered data recorded on two SCFs.…”