Characterization of nerve-cuff electrode interface for biocompatible and chronic stimulating application

Nerve cuff electrodes for peripheral nerve prostheses require chronically implanted electrodes that simultaneously stimulate and record nerve activity. Particularly, the electrical stimulation that is provided should remain below the charge-carrying capacity of the electrode to avoid an irreversible reaction, electrode dissolution, and nerve damage. In this study, stimulating nerve cuff electrodes with Pt, IrOx, poly(3,4-ethylenedioxythiophene) (PEDOT), and platinum black (Pt black) on polyimide were fabricated, and their interface properties were compared for use as a stimulating electrode via in vitro and acute in vivo tests. The experimental results indicated that the stimulating nerve cuff electrodes with Pt black had the highest charge delivery capacity (62 times higher than Pt), the highest charge injection capacity (6 times higher than Pt), and the lowest interfacial impedance (2.9 times lower than Pt). After applying 60,000 biphasic pulses, the electrochemical and physical properties of the cuff electrode with Pt black were extremely well maintained. In addition, the cuff electrode with Pt black exhibited properly and safely transferred charge injection properties in the acute in vivo and preliminary long-term in vivo (15 weeks) test with minimizing nerve damage. As a result, stimulating nerve cuff electrode with Pt black is expected to be suitable for chronically implantable electrode, providing biocompatible and stable electrical stimulation. (C) 2016 Elsevier B.V. All rights reserved.