Optimizing the design of bipolar nerve cuff electrodes for improved recording of peripheral nerve activity.

Optimizing the design of bipolar nerve cuff electrodes for improved recording of peripheral nerve activity.

J Neural Eng. 2017 Mar 02;:

Authors: Sabetian P, Popovic M, Yoo P

Abstract
OBJECTIVE: Differential measurement of efferent and afferent peripheral nerve activity offers a promising means of improving the clinical utility of implantable neuroprostheses. The tripolar nerve cuff electrode has historically served as the gold standard for achieving high signal-to-noise ratios (SNRs) of the recordings. However, the symmetrical geometry of this electrode array (i.e., electrically-shorted side contacts) precludes it from measuring electrical signals that can be used to obtain directional information. In this study, we investigated the feasibility of using a bipolar nerve cuff electrode to achieve high-SNR of peripheral nerve activity.
APPROACH: A finite element model was implemented to investigate the effects of electrode design parameters - electrode length (EL), electrode edge length (EEL), and a conductive shielding layer (CSL) - on simulated single fiber action potentials (SFAP) and also artifact noise signals (ANS).
MAIN RESULTS: Our model revealed that the EEL was particularly effective in increasing the peak-to-peak amplitude of the SFAP (319%) and reducing the common mode ANS (67%) of the bipolar nerve electrode. By adding a CSL to the bipolar cuff electrode, the SNR was found to be 65.2% greater than that of a conventional tripolar electrode. In vivo experiments in anesthetized rats confirmed that a bipolar nerve electrode can achieve a SNR that is 38% greater than that achieved by a conventional tripolar electrode (p<0.05).
SIGNIFICANCE: The current study showed that bipolar nerve cuff electrodes can be designed to achieve SNR levels that are comparable to that of tripolar configurations. Further work is needed to confirm that this bipolar design parameters can be used to record bi-directional neural activity in a physiological setting.

PMID: 28251960 [PubMed - as supplied by publisher]

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