Using a single penetrating interfascicular electrode to improve spatial selectivity of an extraneural polymeric cuff array
File(s)
Published version
Author(s)
Ben M'Rad, Imane
Bailey, Zachary K
Cuttaz, Estelle A
Green, Rylie
Type
Journal Article
Abstract
Background
Damage to the peripheral nervous system severely disrupts motor control, sensory perception, and organ function, often resulting in long-term disability. To restore such impairments, peripheral nerve interfaces (PNIs) aim to achieve precise stimulation selectivity, yet current approaches face several limitations. Most PNIs rely on metal-based electrodes, which introduce a mechanical mismatch with soft neural tissue and are limited by low charge-injection capacity. The device design of these PNIs also suffers from a fundamental trade-off: highly invasive approaches enable high selectivity but provoke strong foreign-body responses, while less invasive designs minimize tissue damage but fail to provide sufficient selectivity. Although current-steering strategies have been explored to enhance selectivity, their performance remains inadequate for clinical application. Significant advances in PNIs are required to safely achieve higher selectivity.
Methods
In this work, a novel array consisting of a single penetrating interfascicular electrode (SPIF) added to an extraneural cuff (EC) array, termed SPIFEC, was developed using laser-based fabrication and polymeric materials. Electrochemical properties were characterized, and ex vivo experiments using whole rat sciatic nerve were conducted to assess fascicular selectivity. The implantation was assessed through computed tomography (CT) imaging.
Results
The SPIFEC design includes seven extraneural electrodes and one double-sided interfascicular penetrating electrode. Electrochemical analysis revealed the polymeric electrodes had low impedance, high charge storage capacity and high charge-injection limit, when compared to previous reports on traditional metallic devices. Ex vivo studies demonstrated that the device achieved high fascicular selectivity, particularly in nerves with well-defined fascicles, outperforming a comparable non-penetrating cuff. CT imaging confirmed the interfascicular positioning of the penetrating electrode.
Conclusion
These results demonstrate the potential of this novel SPIFEC array in enhancing spatial selectivity for peripheral nerve applications. Further studies, including chronic in vivo testing, are required to fully evaluate long-term performance and clinical potential in neuroprosthetic systems.
Damage to the peripheral nervous system severely disrupts motor control, sensory perception, and organ function, often resulting in long-term disability. To restore such impairments, peripheral nerve interfaces (PNIs) aim to achieve precise stimulation selectivity, yet current approaches face several limitations. Most PNIs rely on metal-based electrodes, which introduce a mechanical mismatch with soft neural tissue and are limited by low charge-injection capacity. The device design of these PNIs also suffers from a fundamental trade-off: highly invasive approaches enable high selectivity but provoke strong foreign-body responses, while less invasive designs minimize tissue damage but fail to provide sufficient selectivity. Although current-steering strategies have been explored to enhance selectivity, their performance remains inadequate for clinical application. Significant advances in PNIs are required to safely achieve higher selectivity.
Methods
In this work, a novel array consisting of a single penetrating interfascicular electrode (SPIF) added to an extraneural cuff (EC) array, termed SPIFEC, was developed using laser-based fabrication and polymeric materials. Electrochemical properties were characterized, and ex vivo experiments using whole rat sciatic nerve were conducted to assess fascicular selectivity. The implantation was assessed through computed tomography (CT) imaging.
Results
The SPIFEC design includes seven extraneural electrodes and one double-sided interfascicular penetrating electrode. Electrochemical analysis revealed the polymeric electrodes had low impedance, high charge storage capacity and high charge-injection limit, when compared to previous reports on traditional metallic devices. Ex vivo studies demonstrated that the device achieved high fascicular selectivity, particularly in nerves with well-defined fascicles, outperforming a comparable non-penetrating cuff. CT imaging confirmed the interfascicular positioning of the penetrating electrode.
Conclusion
These results demonstrate the potential of this novel SPIFEC array in enhancing spatial selectivity for peripheral nerve applications. Further studies, including chronic in vivo testing, are required to fully evaluate long-term performance and clinical potential in neuroprosthetic systems.
Date Issued
2025-12-01
Date Acceptance
2025-11-18
Citation
Bioelectronic Medicine, 2025, 11 (1)
ISSN
2332-8886
Publisher
BMC
Journal / Book Title
Bioelectronic Medicine
Volume
11
Issue
1
Copyright Statement
© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
10.1186/s42234-025-00193-6
Subjects
Stimulation selectivity
Nerve cuff electrode arrays
Conductive elastomers
Penetrating electrode
SPIFEC
Publication Status
Published
Article Number
ARTN 29
Date Publish Online
2025-12-20