Direct laser writing of 3D electrodes on flexible substrates

Area of Science:

• Neuroscience
• Materials Science
• Biomedical Engineering

Background:

• Neural recording technologies are crucial for understanding brain function.
• Existing microelectrode arrays face limitations in resolution and adaptability for small animal models.
• Advanced fabrication methods are needed for high-density, high-aspect-ratio neural probes.

Purpose of the Study:

• To develop and demonstrate a novel 3D microelectrode array integrated on a flexible cable.
• To establish a fabrication process combining silicon thin-film techniques and two-photon lithography for high-aspect-ratio structures.
• To evaluate the performance of these arrays for neural recording in small animal models.

Main Methods:

• Fabrication using traditional silicon thin-film processing and direct laser writing (two-photon lithography) for 3D structures.
• Development of high-aspect-ratio electrodes with micron resolution.
• Integration of microelectrodes onto a thin-film flexible cable.

Main Results:

• Successful fabrication of a 16-channel array with 300 µm pitch, demonstrating electrophysiological signal capture in bird and mouse brains.
• Creation of additional devices including 90 µm pitch arrays, biomimetic needles, and porous electrodes with enhanced surface area.
• Demonstration of rapid, wafer-scale fabrication methods.

Conclusions:

• The described 3D microelectrode array technology enables efficient fabrication of compact, high-density electrodes.
• This advancement facilitates new studies on electrode geometry and performance for neural interfaces.
• Potential applications include small animal models, nerve interfaces, and retinal implants.