Rejuvenating silicon probes for acute neurophysiology

Area of Science:

• Neuroscience
• Materials Science

Background:

• Silicon probes are crucial for neurophysiological recordings.
• Signal quality and neuron isolation degrade with repeated use of these probes.
• The cause of this degradation has been unclear, leading to probe disposal.

Purpose of the Study:

• Investigate the cause of signal quality degradation in silicon probes.
• Develop a method to rejuvenate used silicon probes.
• Improve the longevity and performance of neurophysiological recording probes.

Main Methods:

• Tested 12 Cambridge Neurotech silicon probes across 61 recording sessions in marmoset brains.
• Examined probe impedance and neuron isolation before and after repeated use.
• Utilized imaging to identify polymer coating loss as the cause of degradation.
• Developed and applied a recoating process using 3,4-Ethylenedioxythiophene (EDOT) and Poly(sodium 4-styrenesulfonate) (PSS).

Main Results:

• Repeated use led to increased probe impedance and decreased neuron isolation.
• Imaging revealed gradual loss of the conductive polymer coating on probe contacts.
• Stripping and recoating the probes restored impedance to ~50 kΩ.
• Recoated probes demonstrated significantly improved signal quality in neurophysiological recordings.

Conclusions:

• The conductive polymer coating on silicon probe contacts is lost during brain insertion.
• This polymer loss causes neurophysiological signal degradation and reduced neuron isolation.
• A simple recoating procedure effectively rejuvenates silicon probes, extending their usability and performance.