Using spatial summation of multi-site stimulation electrodes to improve the capability of a sensory neural interface

Abstract

When afferents reinnervate the muscle tissue nearby a stimulating electrode, it is hard to control how well the single stimulating site of the electrode aligns physically with the location of the nerve fiber. To account for such issues in positioning, a multi-site electrode might aid by delivering electrical stimulation in a distributed fashion. In particular, by sourcing a smaller magnitude of charge per electrode, it may be possible to reduce the likelihood of tissue damage, even while increasing the extent of tissue above the depolarization threshold. Therefore, the work herein develops a finite-element (FE) model of the electrode-muscle interface to determine the distribution of charge density delivered to muscle as a function of two independent variables and their interaction: 1) interelectrode distance and 2) stimulation amplitude. The results indicate that multi-site electrodes can stimulate more muscle volume at lower input amplitude than a single-site electrode, over a range of tissue properties. Importantly, multisite stimulation may reduce tissue damage and even yet increase the likelihood of stimulating a fiber. Further work is yet needed to tie the modeling results with experimental validation in real tissue.

Optimizing selective stimulation of peripheral nerves with arrays of coils or surface electrodes using a linear peripheral nerve stimulation metric

“…Additionally, device optimization often divides the coil or electrode distribution into a set of discrete Optimizing selective stimulation of peripheral nerves with arrays of coils or surface electrodes using a linear peripheral nerve stimulation metric Mathias Davids 1,2,3,6 , Bastien Guérin 1,2 , Valerie Klein 1,3 , Martin Schmelz 4 , Lothar R Schad 3 and Lawrence L Wald 1,2,5 basis elements [19,36,46,47], and because the total electromagnetic field is the superposition of the fields from individual coil or electrode elements, they can be computed as a weighted linear combination of those basis elements. The boundary element method stream function (BEM-SF) approach for designing coil winding patterns with desired field characteristics is an example of this approach which uses a set of current basis functions to compose all possible current patterns as a weighted combination of the basis functions [23,31,34].…”