Electrochemical Considerations for Safe Electrical Stimulation of the Nervous System with Platinum Electrodes

TLDR

Electrical stimulation of the nervous system is increasingly important for neural prostheses, and three conceptually safe methods of injecting charge from noble metals into tissue have been identified. The study reviews electrochemical reactions at platinum or other noble metal–tissue interfaces. These reactions can be mitigated by using stimulus waveforms lacking a net direct current component and maintaining controlled charge densities. Stimulus waveforms with a net direct current component raise the likelihood of tissue damage.

Abstract

Electrical stimulation of the nervous system is of increasing importance for a variety of prospective neural prostheses. Electrochemical reactions which may occur at Pt or other noble metal-tissue interfaces are reviewed. Use of stimulus waveforms with a net direct current component increases the probability of tissue damage. There are three conceptually safe methods of injecting charge from a noble metal into tissue: modification of the electrical double layer at the interface and coupling via either of two symmetrical surface-layer oxidation-reduction processes. These reactions may be addressed with stimulus waveforms without a direct current component and with controlled charge densities.