Subthreshold Electrical Stimulation for Controlling Protein-Mediated Impedance Increases in Platinum Cochlear...

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Cochlear electrode impedance fluctuations, caused by protein adsorption and inflammation, can negatively impact device performance and longevity.
• Stable electrode impedance is crucial for effective cochlear implant function, influencing power consumption and safe charge delivery.

Purpose of the Study:

• To evaluate subthreshold biphasic stimulation pulses as a method to stabilize cochlear electrode impedance.
• To investigate the control of protein adsorption on electrode surfaces using different stimulation strategies.

Main Methods:

• Measured protein-mediated changes in polarization impedance (Zp) using voltage transient responses and electrochemical impedance spectroscopy.
• Assessed four subthreshold stimulation regimes: continuous symmetric, 10% duty cycle symmetric, 1% duty cycle symmetric, and continuous asymmetric pulses.
• Incubated electrodes in protein solutions with and without stimulation to analyze impedance changes.

Main Results:

• Electrode impedance increased by 28-55% after 2 hours of incubation in protein solutions without stimulation.
• Subthreshold stimulation significantly reduced the rate of impedance increase across all tested protein solutions.
• Continuous stimulation delivery proved more effective in mitigating impedance rise than intermittent (1% and 10% duty cycle) stimulation.

Conclusions:

• Subthreshold stimulation pulses show potential for mitigating protein-mediated impedance increases in cochlear electrodes.
• This approach offers a clinically translatable strategy to enhance the long-term stability and performance of cochlear implants by managing protein adsorption.