Development of an Infrared Nerve Stimulator

1. Greg Wigger, Chris Tedder, and Melanie Gault Advised by: Dr. Duco Jansen, Ph.D. Development of an Infrared Nerve Stimulator

2. The Problem There is a need for an implantabledevice that will reliably stimulate individual nerve fascicles • This requires a reliable stimulation modality to gain better control over neural signals.

3. 10 5 0 -5 0 2 4 6 8 10 12 14 16 Our Solution: Infrared Stimulation 10 5 Electrical Electrical CMAP (V) 0 Stimulator Stimulator -5 0 2 4 6 8 10 12 14 16 Infrared Stimulation Same advantages as electrical stimulation, but: • Less damaging to nerve • Artifact free • Spatially selective CMAP (V) Rat Sciatic Nerve Rat Sciatic Nerve 0.2 Fiber Coupled Fiber Coupled 0.1 Laser Laser CMAP (V) 0 Optical Fiber -0.1 0 2 4 6 8 10 12 14 16 0.2 0.1 CMAP (V) 0 Rat Sciatic Nerve -0.1 0 2 4 6 8 10 12 14 16 Electrical Stimulation Has fundamental shortcomings that create a need for an alternative Contact can cause permanent damage to nerve Stimulation artifact Hard to selectively stimulate

4. Group Objective Develop an infrared nerve stimulator containing optical fibers running parallel to the nerve fibers • Create a single fiber prototype • Create a four fiber prototype embedded in a cuff to be wrapped around entire nerve bundle • Two models will be tested: Fiber with angled mirror Fiber polished at 45 degree angle

5. Past Work • Polished a fiber at 45 degrees • Used varying sized grit paper and worked our way down to 1 µm • Observed beam profile of polished optic fiber

6. Past Work (Continued) • Constructed of proof-of-concept prototype for mirror reflection

7. Current Work • Using the 3D design software, SolidWorks, to draw out the prototype • This information will be used to determine the necessary focal length in smaller scale models Nylon Tubing Optical fiber with insert

8. Current Work (continued) • Knife edge technique to characterize beam width of side firing fiber • Did this in a single direction • In contact with Ocean optics about optical fibers for high power infrared applications • Waiting for infrared transparent epoxy to come in so that we can construct our own.

9. Future Work • Receive larger nylon tubing and mirrors • Current nylon tubing has inner diameter of 0.32 inches (8.128 mm) • The smallest standard concave mirror diameter is 9 mm  we need a larger tube!

10. Future Work (Continued) • Power output analysis for both side-firing techniques • Animal studies of both prototypes? • Development of nerve cuff design with 4 side-firing fibers • Exploration of PDMS for biomaterial • Customized building of best side-firing fiber (custom ordered parts, smaller size, etc.)