smu neurophotonics
TRANSCRIPT
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