Electrochemical enhancement of reactively sputtered rhodium, ruthenium, and iridium oxide thin films for neural modulation, sensing, and recording applications. (20th October 2021)

• Record Type: Journal Article
• Authors: Taylor, Gregory; Paladines, Rhandy; Marti, Anthony; Jacobs, Daaron; Tint, Saxon; Fones, Andrew; Hamilton, Hugh; Yu, Lei; Amini, Shahram; Hettinger, Jeffrey
• Is Part Of: Electrochimica acta. Volume 394(2021)
• Publication Date: 2021-10-20
• Subjects: Reactive magnetron sputtering -- Equivalent circuit model -- High charge storage capacity -- Neural interfacing electrode -- Thin film; IrOx iridium Oxide -- RhxOy rhodium Oxide -- RuOx ruthenium Oxide -- Al2O3 aluminum oxide -- ECM equivalent circuit model -- CV cyclic voltammetry -- EIS electrochemical impedance spectroscopy -- 316-SS 316 stainless-steel -- EDS energy dispersive spectroscopy -- XRD X-ray diffraction -- SEM scanning electron microscope -- AFM atomic force microscope -- CSCC cathodic charge storage capacity -- WP working pressure -- OPP oxygen partial pressure -- WT bounded Warburg element -- WO finite length Warburg element -- CPE constant phase element -- RS solution resistance -- Rdl double layer resistance -- Cdl double layer capacitance -- Rct charge transfer resistance -- Cfar faradaic capacitance -- CPEads imperfect adsorption capacitance; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.139118
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Implantable neural interfacing devices are able to diagnose, monitor, and treat many conditions through modulating and recording electrical signals to and from neural tissue. The efficacy of treatment can be limited by a lack of specificity in targeting of neural tissue. To improve specificity and functionality, the electrodes and microelectrode arrays in these devices must be further miniaturized and must possess exceptional charge exchange characteristics. In this study, rhodium oxide (Rhx Oy ), ruthenium oxide (RuOx ), and iridium oxide (IrOx ) thin films were synthesized using pulsed-DC reactive magnetron sputtering. The effect of sputtering chamber working pressure (WP) on the morphology, crystal structure, chemical composition, and electrochemical properties of the subsequent metal oxide thin films were investigated. The cathodic charge storage capacity (CSCc ) and impedance of films were measured via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Results show that CSCc increases, and the overall impedance decreases with increasing WP in all oxide systems. The enhanced electrochemical performance of these films has been attributed in large part to the morphological changes that occur with increasing WP resulting in an apparent increase in the porosity. This study reviews the electrochemical properties of IrOx, and also demonstrates the viability of Rhx Oy and RuOx as possible electrode coatings for neural interfacing applications.