ID:16079 The Importance of Instrumentation on Measurement of Safe Charge Injection Limits at Neural Stimulation Electrodes

Abstract

The development of safe and efficacious neural stimulation protocols critically depends on the accurate assessment of charge injection limits that do not result in toxic byproducts of stimulation or evolution of oxygen/hydrogen gas at neural stimulation electrodes. Since the introduction of voltage transient or voltage excursion methods by Roblee et al. in 1990, this method has become a standard used by pre-clinical researchers for understanding the charge injection limits of different materials or electrode geometries. It has also become an important part of safety testing for clinical devices and common requirement by FDA reviewers in assessing device safety. Although voltage transient measurements have been commonly applied across neural engineering, assessment of charge injection limits in the presence of baseline voltage offsets at the stimulation electrode has been inconsistent across the literature. Additionally, voltage transient measurements have provided results for safe charge injection limits that are inconsistent with charge injection capacities measured using slow scan cyclic voltammetry as well as with in vitro and in vivo testing. These inconsistencies highlight the need for developing well validated methods for accurate assessment of charge injection limits across studies.