Fabrication of a Multilayer Implantable Cortical Microelectrode Probe to Improve Recording Potential

Area of Science:

• Neuroscience
• Biomaterials Engineering
• Medical Devices

Background:

• Intracortical neural probes are essential for high-fidelity neural signal acquisition in brain-computer interfaces (BCIs).
• Smaller, flexible polymer probes aim to reduce neural tissue response.
• Current fabrication methods limit electrode density on narrow probes.

Purpose of the Study:

• To develop a novel multilayer fabrication process for neural probes.
• To increase the number of recording sites without increasing probe size.
• To enhance electrode density on smaller, more compliant neural probes.

Main Methods:

• Utilized a multilayer fabrication process to vertically layer recording traces on multiple Parylene support layers.
• Defined 16 electrodes (4 per layer) with 30 μm recording windows and 5 μm traces on an 80 μm wide microprobe.
• Electrically characterized probes via impedance spectroscopy and crosstalk evaluation before in vitro and in vivo validation.

Main Results:

• Successfully fabricated microprobes with increased electrode density using a multilayer approach.
• Demonstrated acute in vitro recordings in cerebral organoids and in vivo recordings in murine models.
• Confirmed the probe's capability for single-unit recordings.

Conclusions:

• The multilayer fabrication strategy enables the creation of smaller, more compliant neural probes.
• This method significantly increases electrode density without compromising probe dimensions.
• The developed probes show promise for advanced brain-computer interface applications.