Effect of contacts configuration and location on selective stimulation of cuff electrode.

Abstract

Cuff electrodes have been widely used chronically in different clinical applications. Advancements have been made in selective stimulation by using multi-contact cuff electrodes. Steering anodic current is a strategy to increase selectivity by reshaping and localizing electric fields. There are two configurations for contacts to be implemented in cuff, monopolar and tripolar. A cuff electrode with tripolar configuration can restrict the activation to a more localized region within a nerve trunk compared to a cuff with monopolar configuration and improve the selectivity. Anode contacts in tripolar configuration can be made in two structures, "ring" and "dot".In this study, the stimulation capabilities of these two structures were evaluated.The recruitment properties and the selectivity of stimulation were examined by measuring the electric potential produced by stimulation currents.The results of the present study indicated that using dot configuration, the current needed to stimulate fascicles in tripolar topologies would be reduced by 10%. It was also shown that stimulation threshold was increased by moving anode contacts inward the cuff. On the other hand, stimulation threshold was decreased by moving the anode contacts outward the cuff which would decrease selectivity, too.We conclude that dot configuration is a better choice for stimulation. Also, a cuff inward placement of 10% relative to the cuff length was near optimal.