A silicon neural probe fabricated using DRIE on bonded thin silicon.

Area of Science:

• Neuroscience
• Materials Science
• Biomedical Engineering

Background:

• Parylene-C based neural probes are essential for in-vivo studies.
• Dissolvable needles are used to embed probes, but can affect encapsulation property testing.
• Silicon wafer thinning is challenging to integrate into neural probe fabrication.

Purpose of the Study:

• To develop a novel silicon neural probe fabrication process.
• To enable in-vivo testing of parylene-C encapsulation without confounding factors.
• To integrate silicon wafer thinning into neural probe manufacturing for variable probe thicknesses.

Main Methods:

• Deep reactive ion etching on 250 μm thin silicon wafers.
• Photolithography on substrates bonded with backgrinding liquid wax (BGL7080).
• Electrochemical impedance spectroscopy (EIS) for electrode characterization.

Main Results:

• Fabricated silicon neural probes mimic existing designs for in-vivo testing.
• Successful photolithography on thinned silicon wafers bonded with wax.
• Measured impedance of ~80 kΩ at 1 kHz for platinum electrodes, indicating recording capability.
• Successful recording of neural activity in the substantia nigra of a mouse.

Conclusions:

• The developed deep reactive ion etching process enables fabrication of silicon neural probes.
• This technique allows for effective in-vivo testing of parylene-C encapsulation.
• The probes show promise for studying neural activity, particularly in Parkinson's disease research.