Influences of design aspects on recording functionality of cuff-type peripheral nerve interfaces

High-quality recording of peripheral nerve signals is a critical requirement for implantable neural interfaces, yet the influence of contact configuration and electrical insulation on cuff electrode recording quality remains poorly understood.

Using a physical nerve model in vitro, the transfer function of commercially available split-cylinder and spiral cuff electrodes was measured for systematically varied contact configurations, including contact size, spacing, and size ratio of cathode to anode, as well as degree of electrical insulation. To derive single-fiber and compound action potentials, the transfer function was convolved with modeled action currents, enabling direct comparison of recording quality across designs.

Contact edge spacing was found to be more decisive than contact surface area for recording amplitude, regardless of contact segmentation. In quasi-tripolar configurations, common mode suppression additionally reduced sensitivity to geometric variations. Both the length of the longitudinal insulation and the integrity of the electrode seal were found to strongly influence recording amplitude, with complete removal of the seal reducing amplitude by approximately 50%, outweighing all geometric design parameters combined.

These findings establish electrical insulation integrity as the primary design criterion for cuff electrode recording performance, shifting focus away from contact geometry alone, and provide a practical framework for the development of next-generation peripheral nerve interfaces.