Probes and Electrodes Dr. Lynn Fullerdiyhpl.us/~nmz787/mems/unorganized/mem_probes.pdf · © May 8,...
Transcript of Probes and Electrodes Dr. Lynn Fullerdiyhpl.us/~nmz787/mems/unorganized/mem_probes.pdf · © May 8,...
© May 8, 2012 Dr. Lynn Fuller, Professor
Probes
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Rochester Institute of Technology
Microelectronic Engineering
ROCHESTER INSTITUTE OF TECHNOLOGYMICROELECTRONIC ENGINEERING
Probes and Electrodes
Dr. Lynn FullerWebpage: http://people.rit.edu/lffeee
Microelectronic EngineeringRochester Institute of Technology
82 Lomb Memorial DriveRochester, NY 14623-5604
Tel (585) 475-2035Fax (585) 475-5041
Email: [email protected] Webpage: http://www.microe.rit.edu
5-8-2012 mem_probes.ppt
© May 8, 2012 Dr. Lynn Fuller, Professor
Probes
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Microelectronic Engineering
OUTLINE
IntroductionRecording Electrodes
MEMS Thin Film
VisionVision RestorationHearingCochlear ImplantsHeart RegulationPacemakers and DefribulatorsOtherReferences
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Probes
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INTRODUCTION
Electrical Sensing or Recording ElectrodesElectrical Stimulus ElectrodesChemical Analysis Probes (not discussed in this lecture)
Applications:ResearchVision RestorationHearing RestorationHeart Pacemaker and DefribulationBladder controlMuscle StimulationOther
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MEMS SENSING ELECTRODES
Silicon Electrodes
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RECORDING ELECTRODES
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VISION RESTORATION
In conditions such as retinitis pigmentosa and macular degeneration, the light sensing rod and cone cells ("photoreceptors") no longer function. Visual prostheses, implanted in the brain’s visual cortex, the optic nerve, or in the retina. A retinal prosthesis can be fixated either on the retinal surface (epiretinal) or below the retina (subretinal).
Boston Retinal Implant Project
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THE EYE
Lens
SuspensoryLigament
Ciliary Body
Sclera
PupilCornea
Aqueous Humor
Iris
Biology, 3rd Edition, Neil A. Campbell
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VISUAL CORTEX
Biology, 3rd Edition, Neil A. Campbell
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THE RETINA
Biology, 3rd Edition, Neil A. Campbell
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CONVERSION OF LIGHT
Biology, 3rd Edition, Neil A. Campbell
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THE RETINA
Biology, 3
rdE
dition, Neil A
. Cam
pbell
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GANGLION CELL ACTION POTENTIALS
Biology, 3rd Edition, Neil A. Campbell
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OPTOTRONICS CORPORTION APPROACH
Optobionics Corporation
25 µm thick, 2 mm dia, 5000 microphotodiodes
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CCD CAMERA APPROACH
The retinal prosthesis is designed to bypass damaged photoreceptors (rods and cones) and directly stimulate the surviving ganglion cells connected to the brain through the optic nerve. A camera mounted on specially designed glasses capture the visual scene and transmits this information (in this figure, using an invisible laser beam). The laser strikes a solar panel (photodiode array) located behind the pupil and generates internal power and transmits the encoded visual information. An ultra-thin electrode array carries the power and information to the retinal surface where it stimulates the ganglion cells.
Boston Retinal Implant Project
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Probes
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RETINAL PROSTHESIS
This is a prototype tack for attaching an array to the retina. The tack thickness is 10µ.
Photodiode array made of silicon measuring 2.2 mm2 inserted in a pig retina. The 12 photodiodes are connected in series and can be independently stimulated. In order to function properly within the eye, the array must be hermetically sealed (effectively encapsulated) to prevent its deterioration.
Boston Retinal Implant Project
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DISCUSSION OF LIGHT CONVERSION AND SIGNAL PROCESSING AT THE RETINA
Photo diode converts light to current. Cones and rods in the retina converts light into voltage pulses (action potentials) where information is encoded in the voltage frequency rather than amplitude. Cones and rods communicate with neighboring cells through amacrine, bipolar and horizontal cells. The ganglion cells receive signals from these cells and transmit information along the optic nerve. Further processing is done by the brain.
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Probes
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Microelectronic Engineering
EYE PRESSURE MONITOR
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HEARING RESTORATION – COCHLEAR IMPLANTS
Another application of electrodes is the cochlear implant.
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THE EAR
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THE COCHLEA
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HOW THE COCHLEA WORKS
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CHOCHLEAR IMPLANT
http://www.bcm.edu/oto/jsolab/cochlear_implants/ cochlear_implant.htm
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RIT THIN FILM COCHLEAR IMPLANTS
Ward Johnson, Senior Project, 2006
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THIN FILM RECORDING ELECTRODES4700 µ
m
100 µm
3”
13 pads each sidemade to mate withstandard AMP connector
700 µm300 µm
5400 µm 25000 µm
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Probes
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THIN FILM RECORDING ELECTRODES MADE AT RIT
Take Photograph for Notebook andPaste Here
Take Photographfor Notebook andPaste Here
Keith Udut 1999Dr. Lynn Fuller
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BLOOD FLOW, PRESSURE, CHEMICAL ANALYSIS
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0th VERSION
500 µm
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FIRST VERSION RIT SILICON BIOPROBES
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SECOND VERSION RIT SILICON BIOPROBES
5mm
4.5mm
3.5mm
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SECOND VERSION RIT DESIGN
5mm
5mm
No PadsLC
Two PadsTwo ElectrodesPoly ResistorCapacitorPhoto diodeTemperature DiodeCoil
Three PadsHeater and Thermocouple
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SPRING 2007 PROJECT CHIP – RIT MEMS CLASS
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SECOND VERSION COMPLETED DEVICES - RIT
W1W3
W2
L2
L1
W1 = 300 µmW2 = 1100W3 = 450L1 = 1400L2 = 1250 500 µm20 µm
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THIRD VERSION - BIO PROBES
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Probes
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OXYGEN PROBE
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TEMPERATURE AND CHEMICAL
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BLOOD FLOW
MOVIE
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PROBES AFTER FABRICATION BEFORE SEPARATION
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4THVERSION - TEMP AND CHEMICAL SENSOR PROBE
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POLY DIAPHRAGM FIELD EFFECT TRANSISTOR
75 µm
15 µm
5x
Vsource
Vgate
Vdrain
Etch Holes
Contact Cut
to Poly Gate
Poly
Diaphragm
Vdrain
2 µm n+ PolyVgate
Vsource
P+P+
n-type silicon
Aluminum Plug
1 µm space
1000 Å Oxide
Kerstin Babbitt, 1997
BSEE U of Rochester
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POLY DIAPHRAGM PRESSURE SENSOR TEST RESULTS
No Pressure
Pressure
An Pham – 1999Rochester Institute of Technology
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5TH VERSION CMOS Compatible Tiny Pressure Sensor
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Probes
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Microelectronic Engineering
5TH VERSION CMOS Compatible Tiny Pressure Sensor
© May 8, 2012 Dr. Lynn Fuller, Professor
Probes
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Microelectronic Engineering
5TH VERSION CMOS Compatible Tiny Pressure Sensor
100um
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Probes
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air gap
5TH VERSION CMOS Compatible Tiny Pressure Sensor
N-well
N+
Poly
P- wafer
GateDrainSource
XeF2 etch can remove poly leaving an air gap creating a pressure sensitive oxide diaphragm
Oxide
100 µm
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Probes
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HEART PACEMAKER AND DEFRIBULATION
http://www.bostonscientific.com/templatedata/imports/multimedia/CRM/pro_pacemaker_us.jpg
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FUNCTIONAL DIAGRAM
http://apps.uwhealth.org/health/adam/graphics/images/en/19566.jpg
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Microelectronic Engineering
ADDITIONAL ANATOMICAL POINTS TO CONSIDER
1. Leads in the right ventricle will be in direct contact with the heart wall
2. Leads in the left ventricle are fed through the pulmonary vein and remain unattached
http://www.infomat.net/infomat/focus/health/health_curriculum/images/heart.gif
http://www.3dscience.com/Animations/Heartbeat_AntCut.php
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HEART WALL MOVEMENT SENSOR
We want to make a device that can sense the movement of the wall of the heart. This will help in adjusting the synchronization of the heart muscle response to the electronic pulses from a pacemaker.
A sensor based on Faraday’s principal of electromagnetic induction is proposed. A magnet and the coil have to move relative to each other. Such a sensor measures velocity and creates an output voltage.
A coil wrapped around the pacemaker lead, near the tip, will move with the movement of the heart wall where it is attached. Inside the lead a magnet is levitated in a position near the coil then any movement of the coil will cause a changing magnetic field and an output voltage.
The magnet’s inertia holds it in place, momentarily, as the coil moves. We levitate the free magnet in between two fixed magnets with like poles towards each other creating a restoring force. The magnets are donut shaped and a small wire through the hole prevents the free magnet from flipping thus enabling the restoring, levitation, action to work.
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DESIGN APPROACH
The middle magnet is free and its inertia keeps it stationary (momentarily) when the tip moves. The two end magnets are fixed and oriented with like poles facing the free magnet providing a restoring force to return the free magnet near the coil. The red wire goes through the center of the donut shaped free magnet preventing it from flipping.
Freemagnet
Fixedmagnet
Fixedmagnet
Real Pacemaker Lead
Prototypetip
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FARADAY PRINCIPLE OF ELECTROMAGNETIC INDUCTION
http://micro.magnet.fsu.edu/electromag/java/faraday2/
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MAGNETS
http://www.kjmagnetics.com/
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TEST RESULTS
Signal Amplified x100
Signal no amplification
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REFERENCES
1. “Emerging Prostheses Attempt Vision Restoration”, R&D Magazine, June 2004.
2. Boston Retinal Implant Project, www.bostonretinalimplant.org3. Optobionics Corporation, www.optobionics.com4. Biology, 3rd Edition, Neil A. Campbell, Benjamin/Cummings
Publishing Co. Inc.5. Boston Scientific Co.
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HOMEWORK – MEMS PROBES
1. Search for other applications of MEMS electrodes in biology. Summarize, in your own words, and list your references.