Direct-Print 3D Electrodes for Large-Scale, High-Density, and Customizable Neural Interfaces.

Area of Science:

• Neuroscience
• Materials Science
• Biomedical Engineering

Background:

• Silicon microelectronics offer scalable neural recording but struggle with 3D neural structures due to their planar design.
• Targeting specific neuron populations in complex 3D neural tissue remains a significant challenge for high-resolution neural interfaces.

Purpose of the Study:

• To develop a novel method for fabricating tissue-penetrating 3D microelectrodes integrated with planar microelectronics.
• To enable precise, customizable targeting of distributed neuron populations in three dimensions.
• To demonstrate the technology's efficacy in high-fidelity neural recording, specifically in the retina.

Main Methods:

• Utilized high-resolution 3D printing via 2-photon polymerization and scalable microfabrication techniques.
• Fabricated custom 3D microelectrode shapes, heights, and positions directly onto silicon microelectronic chips.
• Developed 6,600-microelectrode arrays with a 35 µm pitch for large-scale retinal interfacing.

Main Results:

• Achieved precise targeting of retinal ganglion cell (RGC) somas while avoiding the axon bundle layer.
• Obtained high-fidelity, large-scale retinal recordings with minimal axonal interference, a previously undemonstrated capability.
• Confocal microscopy confirmed accurate microelectrode placement within the neural tissue.

Conclusions:

• The developed 3D microelectrode fabrication method offers a versatile solution for large-scale, cellular-resolution interfacing between silicon microelectronics and complex 3D neural structures.
• This technology advances the potential for sophisticated neural recording and modulation in various neuroscience applications.
• The precise targeting demonstrated in the retina opens new avenues for understanding and treating visual system disorders.