Fabrication of Subretinal 3D Microelectrodes with Hexagonal Arrangement

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Retinal prosthetic devices require optimized electrode design to minimize current dissipation and enhance visual perception.
• Existing microelectrode arrays often face challenges in achieving localized retinal cell activation and efficient neural stimulation.

Purpose of the Study:

• To fabricate novel three-dimensional (3D) microelectrodes for subretinal stimulation.
• To investigate the efficacy of a hexagonal electrode arrangement for localized retinal cell activation.
• To enhance visual acuity through improved stimulation efficiency in retinal prosthetic applications.

Main Methods:

• Fabrication of 3D microelectrodes using a customized pressing process with elastic materials.
• Application of a hexagonal arrangement for 98 platinum-coated electrodes (150 μm diameter, 350 μm pitch) on a polydimethylsiloxane (PDMS) base.
• Coating with parylene-C for focused stimulation, followed by electrochemical characterization (impedance and charge storage capacity).

Main Results:

• Successfully fabricated 3D microelectrodes with protruded structures (approx. 20 μm height).
• Achieved a mean impedance of 384.87 kΩ at 1 kHz and a charge storage capacity (CSC) of 2.83 mC·cm⁻².
• Demonstrated the potential for localized activation of retinal cells via hexagonal arrangement and focused stimulation.

Conclusions:

• The developed 3D microelectrodes offer a promising approach for advanced retinal prosthetics.
• The hexagonal arrangement and 3D structure contribute to more efficient and localized neural stimulation.
• Further in vitro and in vivo experiments are warranted to validate the performance in integrated systems.