Mass changes and dissolution of platinum during electrical stimulation in artificial perilymph solution

Area of Science:

• Electrochemistry
• Materials Science
• Biomedical Engineering

Background:

• Platinum electrodes are used in biomedical implants.
• Understanding platinum's electrochemical behavior in biological fluids is crucial for device safety and longevity.

Purpose of the Study:

• To investigate the electrochemistry of platinum electrodes in artificial perilymph.
• To determine the impact of amino acid adsorption on platinum electrode performance and dissolution.
• To assess the safety of platinum dissolution for implanted auditory prostheses.

Main Methods:

• Quartz crystal electrochemical microbalance (QCMB) was used to monitor mass changes.
• Electrolyte analysis quantified dissolved platinum concentrations.
• Cyclic voltammetry and steady-state potential experiments were performed.

Main Results:

• Amino acid adsorption blocks platinum oxidation and oxide reduction sites.
• Cysteine strongly interacts with platinum, reducing voltammogram features and increasing dissolution.
• Human serum albumin inhibited platinum dissolution without significant mass changes.
• Dissolved platinum levels were generally low (<5 ppb), with highest concentrations in cysteine solutions.

Conclusions:

• Amino acids influence platinum electrode electrochemistry by competing with chloride ions.
• Platinum dissolution from auditory prosthesis electrodes is unlikely to reach toxic levels in the body.
• The study provides critical data for the safe design and application of platinum-based biomedical devices.