Transparent indium-tin oxide electrode patterns for extracellular, multisite recording in neuronal cultures

Area of Science:

• Neuroscience
• Materials Science
• Biotechnology

Background:

• Neuronal recording technologies are crucial for understanding brain function.
• Developing high-density microelectrode arrays is essential for advanced neural interfaces.
• Existing microelectrode materials face limitations in biocompatibility, cost, or recording performance.

Purpose of the Study:

• To evaluate indium-tin oxide (ITO) as a novel thin film material for microelectrode fabrication.
• To assess the biocompatibility and recording characteristics of ITO microelectrodes in neuronal cultures.
• To explore the potential of ITO for creating high-density neural recording systems.

Main Methods:

• Fabrication of thin film indium-tin oxide (ITO) microelectrodes on glass substrates.
• Culturing of mammalian spinal neurons on ITO-coated glass plates.
• Electrophysiological recordings of neuronal spike potentials using ITO microelectrodes.
• Impedance and noise level measurements at 1 kHz.
• Comparison with conventional gold-plated electrodes.

Main Results:

• ITO microelectrodes (100 nm thick, 10 microns wide) successfully recorded neuronal spike potentials.
• ITO is non-toxic to mammalian spinal neurons and stable in culture medium.
• Laser-deinsulated ITO craters (100 μm²) exhibited high impedances (8-10 MΩ) and low noise (40 μV).
• Conventional gold plating resulted in lower impedances (<3 MΩ).
• ITO's high light transmittance allows unobstructed microscopic observation.

Conclusions:

• Indium-tin oxide (ITO) is a promising, biocompatible material for fabricating high-performance microelectrodes.
• ITO microelectrodes offer superior impedance characteristics compared to gold plating for neuronal recordings.
• The properties of ITO facilitate the development of cost-effective, high-density neural recording arrays exceeding 400 electrodes/mm².