DARPA CIPhER Program Industrial Advisory Board MeetingJanuary 7, 2011SMU, Dallas TX

Prof. Marc P. Christensen, Prof. Volkan Otugen, Prof. Duco Jansen, Prof. Anita Mahadevan-Jansen,

Prof. Guenter W. Gross, Prof. Dustin Tyler, Prof. Duncan MacFarlane

Neurophotonics Research CenterNeurophotonics Research Center

Mission: Establish a focused university & industry collaborative research center with the mission to: research, prototype, & test novel photonic interfaces to neurons & nerve cells for the purposes of developing highly capable implants for advanced prosthetic devices, novel treatments, and improving understanding of applied neuroscience.

The ChallengeThe Challenge

Problem:•1,286 Soldiers / 50,000 Civilian Amputees•259,000 Spinal Cord Injuries•$500K-$750K Lifetime Costs•Electronic Neural Interface for Neuroscience, Brain-Machine Interfaces and Prosthetics:

– High impedance, high noise– Not MRI compatible– Long term unit recording

Is there a better way to sense and stimulate neural activity?

(preferably without metal, semiconductor or retro-viruses)

VisionVision

Whispering Gallery Mode sensor embedded in engineered fiber

Selective Infrared Neural Stimulation

Complete Neurophotonic Interface

Brain creates nerve signal of motion intent

Brain creates nerve signal of motion intent

Electro-chemical wave modifies microsphere WGMs causing change

in optical signal in fiber

Electro-chemical wave modifies microsphere WGMs causing change

in optical signal in fiber

Change in optical signal is translated

into electrical control signal for prosthetic

arm

Change in optical signal is translated

into electrical control signal for prosthetic

arm

Prosthetic arm moves and sensors provide electrical feedback signals

of pressure, temperatures, etc.

Electrical feedback signals are converted

into optical signals targeting specific sensory nerves

Electrical feedback signals are converted

into optical signals targeting specific sensory nerves

Optical signal stimulates targeted

sensory nerves

Optical signal stimulates targeted

sensory nerves

Brain perceives feedback from sensory nerves

Brain perceives feedback from sensory nerves

Brain

In Vivo Biocompatible Optical Interface

Implantable ControlElectronics

Advanced Prosthetic Arm

All steps performed in real time to enable natural movement.

The ApproachThe Approach

• State of the Art:

• High impedance• High noise• MRI compatibility issues• Problem with long term unit

recording• Established approach• Limited Bandwidth

• This Effort:

• Improved Interface• Reduced noise• MRI compatible• Known Biocompatible Materials• Revolutionary• Leverages Optical Networking BW

Silicon Grid Array Brain Probe

Electronic Nerve Cuff

Glass & PolymerOptical Neural Sensor

Bi-direction Biocompatible Optical Nerve Cuff

Technology ComparisonTechnology Comparison

The TeamThe Team

Prof. Tindaro IoppoloDepartment of Mechanical Engineering

Southern Methodist University

Research Professor

Whispering Gallery Mode Sensor Development

WGM Sensor DevelopmentWGM Sensor Development

Mission: Establish a focused university & industry collaborative research center with the mission to: research, prototype, & test novel photonic interfaces to neurons & nerve cells for the purposes of developing highly capable implants for advanced prosthetic devices, novel treatments, and improving understanding of applied neuroscience.

WGM PhenomenonWGM Phenomenon

Term coined by Lord Rayleigh who visited the St. Paul's Cathedral

A whisper can be heard by someone standing against the opposite wall, but not by someone standing at the center of the room

Light undergoes total internal reflection

It is trapped inside the sphere

Light travels much like a whisper around the whispering gallery

Whispering Gallery Mode SensorsWhispering Gallery Mode Sensors

By monitoring WGM shifts the change in the physical condition can be determined with extreme resolution

Laser

Microsphere

Optical fiber/ waveguide PD

Exploits optical modes of dielectric micro-resonators

Resonators are spheres of different size (50 um – 1 mm), structure, and materials

WGMs of micro-spheres can exhibit extremely large optical quality factors

Change in physical condition surrounding the dielectric resonator leads to a perturbation in resonator morphology resulting in WGM shift

Can be extended to sensor networks

Recent WGM Sensor StudiesRecent WGM Sensor Studies

• Metrology• Temperature sensing • Force/strain sensing• Wall shear stress sensor• Concentration / species detection • Pressure sensitivity• Magnetic field detection/actuation• Electric Field DetectionElectric Field Detection

WGM Sensor CharacterizationWGM Sensor Characterization

125 um Silica fiber

50 um PDMS sphere

Spectrum

Prof. Guenter W. GrossCenter for Network Neuroscience

University of North Texas

UNT Site Director

Toxicity and In Vitro Testing

Toxicity and In Vitro TestingToxicity and In Vitro Testing

Mission: Establish a focused university & industry collaborative research center with the mission to: research, prototype, & test novel photonic interfaces to neurons & nerve cells for the purposes of developing highly capable implants for advanced prosthetic devices, novel treatments, and improving understanding of applied neuroscience.

chamber with sciatic nerve

Optical probe holder with fiber optics and sensor bead (enhanced with color)

CAP:compound action potential (~3 mV) S: stimulus pulse; SA: stimulus artifact

Experimental platform

S

CAP

SA

CAP

Dry Run: Experiment AssemblyDry Run: Experiment Assembly

Fixed and Bodian-stained culture 92 d.i.v..

Optical information during recording is important.

““ordered” networks ordered” networks are temporally are temporally unstable and unstable and optically optically challenged.challenged.

Plexon preampsPlexon preamps

Living cells on MEAs. Phase contrast. Arrows in point to electrode craters. Bar: 40 um. Lower panel: living cell and subsequent necrosis from zinc toxicity.

200 uM Zn++

10% CO2

in air

Heated cap to prevent condensation

Multichannel WorkstationMultichannel Workstation

Electrode selection client

Selected electrode window

ACTION POTENTIAL SIGNATURES

30 sec sterile assembly30 sec sterile assembly

network area

AP threshold crossing provide a time stamp (25 us resolution; 40 kHz scanning rate).

Time stamp display (raster) for all discriminated units. Colors represent different units on the same electrode (4 max)

40 sec

Real Time Data Acquisition & DisplayReal Time Data Acquisition & Display

Toxicity TestingToxicity Testing

1

1

2

2 3

3 4

4 5

5 6

6

40 m

WGM Bead

Plexon Display

uManipulator Control

uManipulator

Chamber

Amplifiers

Microscope

Tight geometry w. condenser closed

Probe

ThermocoupleGas and Water

Numbered electrodes

Heater

Pressure Bars