Cyclic Voltammetry Study of Noble Metals and Their Alloys for Use in Implantable Electrodes

Abstract

Innovation in the application and miniaturization of implantable electrodes has caused a spike in new electrode material research; however, few robust studies are available that compare different metal electrodes in biologically relevant media. Herein, cyclic voltammetry has been employed to compare platinum, palladium, and gold-based electrodes’ potentiometric scans and their corresponding charge storage capacities (CSCs). Ten different noble metals and alloys in these families were tested under pseudophysiological conditions in phosphate-buffered saline (pH 7.4) at 37 °C. Charge storage capacity values (mC/cm 2 ) were calculated for the oxide reduction, hydrogen adsorption, hydrogen desorption, and oxide formation peaks. Five scan rates spanning 2 orders of magnitude (10, 50, 100, 500, and 1000 mV/s) in both sparged and aerated environments were evaluated. Materials have been ranked by their charge storage capacities, reversibility, and trends discussed. Palladium-based alloys outperformed platinum-based alloys in the sparged condition and were ranked equally as high in the aerated condition. The Paliney 1100 (Pd-Re) alloy gave the highest observed calculated CSC value of 0.64 ± 0.02 mC/cm 2 in the aerated condition, demonstrating 73 ± 5% reversibility. Trends between metal electrode families elicited in this study can afford valuable insight into future engineering of high performing implantable electrode materials.

Removal Forces of a Helical Microwire Structure Electrode

“…However, using Gold as a stimulation electrode in vivo presents electrochemical limitations. Gold electrodes tend to exhibit lower charge storage and charge injection capacities relative to Platinum and Iridium electrodes [ 33 ]. In addition, Gold is susceptible to dissolution under a high current density and high frequency stimulation conditions, particularly during the anodic phase of stimulation pulsing [ 34 ].…”

Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies

“…The parameters for a non-Faradaic reaction are desired in electrode implantation to promote biostability of the electrode, and are represented as the water window as shown in Figure 10 . Similar to EIS, CV requires a working electrode, a counter electrode, a reference electrode, and an electrolyte ( Elgrishi et al, 2018 ; Jerkiewicz, 2022 ; Puglia and Bowen, 2022 ). During the execution of this technique, a triangular potential waveform is applied, while measuring the current between the working and counter electrodes.…”

Insights into Structural Behaviors of Thiolated and Aminated Reduced Graphene Oxide Supports to Understand Their Effect on MOR Efficiency

“…The electrochemically active surface area (ECSA) of the electrode surfaces was determined from cyclic voltammograms recorded in degassed H 2 SO 4 0.5 M solution at room temperature with potentials between −0.6 and 1.5 V at a scan rate of 50 mV s –1 . The values of the ECSA and the amount of the Pt catalyst ( m Pt ) in the samples can be estimated as follows , m Pt = Q H M 4 F ECSA = Q H .25em ( μ C ) m Pt × 210 .25em μ C .25em normalc m − 2 .25em ( normalm 2 normalg − 1 ) where Q H is the amount of charge that varies along the surface of Pt during the hydrogen adsorption–desorption process, M is the atomic weight of Pt (195.09 g mol –1 ), and F is the Faraday constant (96485.309 C mol –1 ).…”

“…The charge of the hydrogen adsorption−desorption process (Q H ) was estimated from the integral of the peak area shown in the current vs time plot (Figure S5). 31 The ECSA S Pt was then extracted from hydrogen adsorption−desorption charge as mentioned above (Table 2). It was found that the value of S Pt on GNH@PtNPs is about 2.4× larger than that on GSH@PtNPs.…”