Parylene flexible neural probes integrated with microfluidic channels

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Flexible probes are essential for neural recording.
• Improving probe stiffness is crucial for successful tissue insertion and stable recordings.
• Microfluidic channels offer multi-functional capabilities within probes.

Purpose of the Study:

• To develop a flexible probe with an integrated microfluidic channel.
• To enhance probe mechanical stiffness using a fillable channel.
• To demonstrate the probe's capability for chemical injection, neural activity measurement, and in vivo application.

Main Methods:

• Fabrication of a 10-microm-thick microfluidic channel using sacrificial photoresist patterns.
• Embedding the channel within a flexible probe.
• Filling the channel with polyethylene glycol (PEG) to increase mechanical stiffness.
• Electrode impedance measurement (100 kOmega at 1 kHz).
• In vivo testing in a rat brain for neural signal recording.

Main Results:

• Successful integration of a microfluidic channel into a flexible probe.
• Polyethylene glycol (PEG) effectively increased probe stiffness.
• The probe demonstrated stable neural signal acquisition in a rat brain.
• Electrode impedance was suitable for neural recording.

Conclusions:

• The developed flexible probe with a microfluidic channel is a versatile tool for neuroscience research.
• The PEG-filled channel provides a viable method for enhancing probe stiffness.
• The probe successfully enabled both neural recording and potential for chemical delivery in vivo.