Greg Wigger, Chris Tedder, and Melanie Gault Advised by: Dr. Duco Jansen, Ph.D.

 This requires a reliable stimulation modality to gain better control over neural signals. There is a need for an implantable device that will reliably stimulate individual nerve fascicles

Infrared Stimulation Same advantages as electrical stimulation, but:  Less damaging to nerve  Artifact free  Spatially selective 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 Rat Sciatic Nerve Electrical Stimulator CMAP (V) Rat Sciatic Nerve Electrical Stimulator CMAP (V)

Develop an infrared nerve stimulator containing optical fibers running parallel to the nerve fibers  Create a single fiber prototype that sends infrared signal at 90 ° angle  Three models will be tested Fiber with flat angled mirror Fiber polished at 45 degree angle Fiber with concave angled mirror

 Biocompatibility – PEGylation  Minimal Power Loss  Small Beam Size  Energy Density  Low Cost  Durability Flat Mirror PrototypeCurved Mirror Prototype

 Implantable devices for use in victims of paralysis  Incorporation of sensors to provide brain with feedback from the external environment

 Completed Solidworks  Tested nylon tube for infrared break down  Determined beam size, energy density, and power loss of 45 °- polished fiber and curved mirror prototype with “Knife- Edge Technique” Before After

 Energy Density and Beam Area  10-fold difference in energy density and order of magnitude difference in spot area of the beam

 Power Loss  Coupling loss measured from the laser to the fiber ▪ Faulty lens?  Nylon is either scattering or absorbing infrared light as seen in large loss from fiber to nylon ▪ Future direction

 Determine if nylon scatters or absorbs light by flattening a piece of nylon and measure loss and spot size  Find absorption spectra of nylon  Calculations  Find theoretical spot size of concave mirror and compare it to actual measured spot size  Find maximum distance that the fiber can be from the concave mirror without any light being lost

 Obtain capillary tube (600 µm ID)to determine if glass is more transparent to infrared light than the nylon tubing  We will conduct an energy-loss test using the angle-polished fiber  Determine the actual distance at which the curved mirror focuses  Place 100 µm pinholes over power meter

 Still waiting on our flat mirrors to arrive…  Optimistic about about its feasibility and effectiveness:  Unnecessary to polish the fiber, as with angle- polished model  Convergence/divergence are non-issues, as with concave model