[Development of An Implantable Optrode for Optogenetic Stimulation]

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Optogenetics requires precise tools for stimulating neural populations.
• Existing methods may lack the necessary flexibility, illumination range, or long-term stability for in-vivo research.
• Developing advanced implantable devices is crucial for understanding neural circuits.

Purpose of the Study:

• To develop and characterize a novel implantable optrode for optogenetic stimulation.
• To evaluate the optrode's performance in terms of optical output, stability, and stimulation efficacy.
• To demonstrate the optrode's utility in modulating neural activity and behavior in animal models.

Main Methods:

• Fabrication of a flexible polyimide-based optrode with integrated micro-light emitting diodes (LEDs).
• Coating the optrode with Parylene C for insulation and biocompatibility.
• Characterization of optical power, illumination area, and long-term stability in physiological saline.
• In-vivo testing in mice to assess stimulation of Channelrhodopsin-2 expressing neurons and behavioral changes.

Main Results:

• The optrode measured 500μm in width and 310μm in thickness, with a ~1μm Parylene C coating.
• Maximum optical output power reached 9.31 mW, illuminating a 3.03mm² area at 650μm depth.
• The device remained functional for 14 days in saline and successfully evoked robust neural spiking and behavioral changes.

Conclusions:

• The developed implantable optrode offers a large effective illumination range and flexible, long-term implantation capabilities.
• This new tool provides a valuable method for optogenetic research on neural populations in nuclei and complex circuits.
• The optrode's performance supports its application in advancing our understanding of brain function through precise neural control.