Development of an Infrared Nerve Stimulator

Greg Wigger, Chris Tedder, and Melanie Gault

Advised by:Dr. Duco Jansen, Ph.D.

The Problem

Current prosthetic limbs cannot mimic the fine tuned movements of human limbs.

Creates a need for a reliable stimulation modality to gain better control over neural signals.

Current prosthetic limbs do not fully replace function of native limbs

Overview of Neural Stimulation The nervous system controls our bodily

functions, decision making, emotions, and more

Neural information is transmitted via action potentials (APs)

APs travel down the nerve until reaches its target

APs propagate due to the opening and closing of gated sodium-ion and potassium-ion channels

Electrical stimulation opens voltage gated channels to cause neural activation

Infrared neural stimulation induces neural activity through an unknown mechanism

Current Solution: Electrical Stimulation

Gold standard for neural stimulation

Easily controllable parameters (current, voltage, repetition rate)

Spatially specific in contrast to other forms of stimulation including chemical and mechanical stimulation.

Cardiac Pacemaker

Cochlear Implant

Spinal Implant

Vagus Nerve Stimulation

Our Solution: Infrared Stimulation

Infrared StimulationSame advantages as electrical

stimulation, but: Less damaging to nerve Artifact free Spatially selective

Electrical StimulationHas 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

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05

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CM

AP

(V

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Rat Sciatic Nerve

Electrical Stimulator

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0 2 4 6 8 10 12 14 16

CM

AP

(V

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Fiber Coupled Laser

Rat Sciatic Nerve-0.1

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0.1

0.2

0 2 4 6 8 10 12 14 16

CM

AP

(V

)

-0.1

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0.1

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0 2 4 6 8 10 12 14 16

CM

AP

(V

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Fiber Coupled Laser

Optical Fiber

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

Past Work

Research of nerve stimulation techniques Electrical stimulation Infrared stimulation

Ordered supplies for prototype Steep tubing, mirrors, optical

fibers, plastic tubing Testing of Ho:YAG laser

80 to 100mJ with 960V power supply

Current Work

Further testing of laser output Attaining an optic fiber polisher Training for animal studies through

IACUC Begin building side-firing prototypes

Future Work

Polishing fibers (flat and 45˚) Biomaterial of the nerve cuff

Research Biocompatibility and optical testing of PDMS

Proof-of-concept experimentation of side-firing with animal studies

Nerve cuff design Adjustable circumference Locking device Positioning of optic fibers