Implantable nanostructured MEA with biphasic current stimulator for retinal prostheses

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Retinal prosthetic systems require microelectrodes to stimulate retinal neurons effectively.
• Minimizing electrode-electrolyte interface impedance is critical for sufficient current delivery at a given voltage.

Purpose of the Study:

• To present the fabrication of a nanostructured microelectrode array with simplified methods.
• To evaluate the characteristics of these microelectrodes using a biphasic current stimulator.

Main Methods:

• Fabrication of nanostructured microelectrodes with base diameters of 25 μm, 50 μm, and 75 μm.
• Measurement of maximum allowable current injection limits.
• Fabrication of a biphasic stimulator with adjustable load resistance (5 kΩ to 20 kΩ) capable of driving 50–200 μA stimulation current.

Main Results:

• Electrode-electrolyte interface impedance values of 3178 Ω, 1218 Ω, and 798.8 Ω were achieved for 25 μm, 50 μm, and 75 μm diameter electrodes, respectively.
• Verification of estimated current injection limits.

Conclusions:

• Nanostructured microelectrode arrays offer advantages for high-resolution retinal prostheses.
• This research serves as a foundational experiment for artificial retina development.