Circumferential Neural Interfaces

Circumferential neural interfaces are soft, ultrathin electrode arrays designed to wrap around nerves or the spinal cord. Instead of penetrating neural tissue, they conform to its surface and place multiple recording and stimulation sites around the full perimeter of the structure.

This geometry gives the interface access to signals that are missed by flat or single-surface devices. Around peripheral nerves, it enables selective access to different fascicles within the same nerve. Around the spinal cord, it opens a route to dorsal, lateral, and ventral pathways that carry sensory information, motor intent, and autonomic signals.

Why circumferential?

Most neural interfaces force a tradeoff between selectivity and invasiveness. Conventional cuffs are safer but often coarse. Penetrating arrays can be selective but damage tissue and are vulnerable to chronic inflammation. Circumferential thin-film devices aim to sit between those extremes: high spatial coverage with a low-profile, non-penetrating implant.

The design priorities are practical as much as technical:

• Conformability: micron-scale parylene-based arrays follow curved neural anatomy.
• Low impedance: PEDOT:PSS-coated electrodes improve recording and stimulation performance.
• Coverage: distributed electrodes sample multiple surfaces and signal directions.
• Translation: surgical approaches are designed around preserving tissue integrity.

Peripheral nerve interfaces

In peripheral nerves, our work focuses on cuffs that can record and stimulate below the whole-nerve level. The goal is to move beyond crude on/off modulation and toward selective control of individual functional channels within a nerve. These ultraconformable cuffs have recorded action potentials from awake animals, resolved fascicle-specific signals, estimated conduction velocity and propagation direction, and delivered stimulation that produces distinct paw movements. In neuropathic pain models, the same platform can track changes in C-fibre activity during disease development.

Spinal cord interfaces

The spinal cord is not only a stimulation target. It is also a rich recording site where descending motor commands, ascending sensory information, and autonomic signals converge. Circumferential spinal interfaces are built to access that distributed activity from the surface of the cord. The i360 platform demonstrated 360-degree recording and stimulation around the spinal cord in rats, including simultaneous access to dorsal, lateral, and ventral surfaces. This enabled proof-of-concept closed-loop spinal cord bypass experiments and provided early safety and human cadaver feasibility data.

Our latest in-press work extends this concept toward freely moving animals. At a high level, it shows that surface circumferential spinal recording can support naturalistic motor decoding and sensory classification from a single conformal interface, without requiring penetrating electrodes. The key idea is integration: one soft interface capable of listening to multiple spinal domains rather than treating motor, sensory, and visceral function as separate problems.

Selected papers

Lei Jiang, Ben Woodington, Alejandro Carnicer-Lombarte, George Malliaras, Damiano G. Barone. Spinal cord bioelectronic interfaces: opportunities in neural recording and clinical challenges. Journal of Neural Engineering 19, 021003 (2022). DOI: 10.1088/1741-2552/ac605f

Ben J. Woodington et al. Flexible circumferential bioelectronics to enable 360-degree recording and stimulation of the spinal cord. Science Advances 10, eadl1230 (2024). DOI: 10.1126/sciadv.adl1230

Alejandro Carnicer-Lombarte et al. Ultraconformable cuff implants for long-term bidirectional interfacing of peripheral nerves at sub-nerve resolutions. Nature Communications 15, 7523 (2024). DOI: 10.1038/s41467-024-51988-1

Salim El Hadwe et al. Surface circumferential spinal cord recording in freely moving rodents. In press.