A 3D glass optrode array for optical neural stimulation

Area of Science:

• Biomedical Engineering
• Materials Science
• Neuroscience

Background:

• Optogenetic and infrared neural stimulation require efficient light delivery systems.
• Developing microscale optical probes (optrodes) is crucial for precise neural interfacing.
• Fused silica offers potential for robust and biocompatible optrode fabrication.

Purpose of the Study:

• To optically characterize a novel SiO(2) optrode array for neural stimulation.
• To evaluate light delivery efficiency and loss mechanisms in fused silica optrodes.
• To assess the suitability of these optrodes for deep tissue optical access.

Main Methods:

• Micromachining of fused silica and quartz discs to create 10x10 optrode arrays.
• Characterization of light in-coupling using optical fibers and collimated beams.
• Measurement of transmission efficiency, transmittance, and output beam profiles for various optrode geometries.

Main Results:

• Highest transmission efficiency of 71% achieved with a 50-μm multi-mode fiber.
• Optrode length and tip angle did not impact output power.
• Optrode width and tip angle independently influenced beam size and divergence.

Conclusions:

• The SiO(2) optrode array is a viable waveguide for optogenetic and IR neural stimulation.
• Fabricated optrodes demonstrate robust performance for light delivery in biological tissues.
• Geometric parameters like width and tip angle can be optimized to control light output characteristics.