an assortment of electrical and computer engineering topics in biomedical engineering edward (ted)...
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An Assortment of Electrical and Computer Engineering Topics in
Biomedical Engineering
Edward (Ted) A. ClancyDepartment of Electrical and Computer Engineering
Department of Biomedical EngineeringWorcester Polytechnic Institute, USA
EAC12–100c
Copyright Edward A. Clancy, 2011. Some rights reserved. Content in this presentation is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License. This license is more fully described at: http://creativecommons.org/licenses/by-nc-sa/3.0/.
Many of the videos shown during this presentation are posted at: http://ece.wpi.edu/~ted/teach.htm
Electrical Activity in the Human Body
Biosignal Electrical activity of the …
Example Uses
Electrocardiogram
(ECG or EKG)… heart
(www.aic.cuhk.edu.hk)
- Patient monitoring
- Diagnose “heart attack,” arrhythmia
Electroencephalogram
(EEG)… brain
(www.cogneuro.ox.ac.uk)
- Anesthesia monitoring
- Seizure analysis
Electromyogram
(EMG)… muscles
(people.uleth.ca )
- Prosthesis control
- Motion control, ergonomics studies
- Clinical EMG exam
- Clinical gait analysis
- Sports, exercise
Electrophysiologic Monitoring
EAC08–201
ECG Arrhythmias
• Abnormal rates (fast, slow, varied, notnot varied!)
• Abnormal shapes
EAC08–204
www.physionet.org
Electrophysiologic Monitoring
Measuring Respiration from ECG
• Respiration modulates the ECG!
• Many more direct measures– Chest band, capnograph (for CO2), chest
impedance
EAC08–205a
Moody et al., Computers in Cardiology 12:113–116, 1985.
Electrophysiologic Monitoring
“Alternation is Everything”
• Alternans– Every other
beat alternation in shape
– Associated with sudden cardiac death
EAC08–206
Healthy
Alternans
Clancy M.S., 1987.
Electrophysiologic Monitoring
Ambulatory Monitors
www.nihonkohden.com
EAC08–207
Monitor abnormal rates, shapes, etc.
ECG, Blood pressure, SaO2, respiration, …
Electrophysiologic Monitoring
EEG—Electroencephalogram
• Electrical activity of the brain
EAC08–208
www.abc.net.au
Electrophysiologic Monitoring
Some Characteristic EEG
EAC08–209
medical-dictionary.thefreedictionary.com
Electrophysiologic Monitoring
Epilepsy• Abnormal brain
discharges– Altered
consciousness, abnormal movement/ sensation, changed behavior
– Seizures
• EEG: Spike discharges
EAC08–210
epilepsygroup.com
Electrophysiologic Monitoring
Motor Unit Decomposition
EAC08–211
Sweep speed = 10 ms/div; Sensitivity = 1.0mV/div
Motor unit potential with reinnervationDecomposition Shows:
• Firing times, firing shapes
• Scientific, physiologic, clinical information
(http://www.neuro.wustl.edu/neuromuscular/pathol/diagrams/linkedpot.htm)
Partial Denervation: EMG
• High amplitude, long duration, polyphasic, late potentials
Electrophysiologic Monitoring
Neuro-Prostheses
• “Emerging” field; Sub-set of neural engineering
• Any prosthesis related to nerves, e.g.– Brain– Sensory nerves– Motor nerves
• Early successes:– Cochlear implants– Deep brain stimulation
EAC09–002
Neuro-Prostheses
Cochlear Implants
EAC09–003
www.hearingloss-wa.org www.childrensspecialists.com
Restore Hearing
Neuro-Prostheses
Deep Brain Stimulation
• Reduce tremor in Parkinson’s
• Suppress depression ‒ experimental
EAC09–004
www.henryfordhealth.org
Neuro-Prostheses
Other Neuroprosthesis Research
• Artificial vision– Retinal and cortical prostheses
• Cortical and deep brain implants
• Motor neuroprostheses
• Functional electrical stimulation
• Artificial sensation– Motor position, velocity, force; temperature
EAC09–005
Neuro-Prostheses
Goal: 1970’s “Six Million Dollar Man”
EAC09–006
See file: “sixmilliondollarman.flv”
Limb Prostheses
Video available on YouTube.com
Body-Powered Upper Limbs• Basic concepts date to civil War
medicine
EAC09–007
See file: “Prosthetic Arm Tip #2: Tying a Shoe.flv”
Limb Prostheses
Video available on YouTube.com
EMGamp: Myoelectric Control of Prosthesis
EAC09–008
• Use remnant muscle EMG to command electric hand, wrist, elbow– Some lower limb prosthetics research
Boston Elbow — Liberating Technologies,
Holliston, MA
Limb Prostheses
EMG Amplitude (EMGamp) Estimation
EAC09–009
EMGamp
EMG amplitude 0–10 mV (~1.5 mV rms)Surface EMG frequency bandlimited at 2000 Hz
• EMG Amplitude (EMGamp): “Intensity” of recorded EMG– “Time-varying standard deviation of EMG signal”
• Original estimator: Inman et al. [1956]– Analog full-wave rectify and RC low pass filter
Electrode-Amplifier
(From Liberating Technologies)
– Varies with force
Limb Prostheses
Nerve Re-Innervation for Myocontrol
RIC Arm; www.popsci.com
• Kuiken nerve re-innervation surgery
• Nerves from severed limb re-connected to pectoralis muscle regions
• Several myocontrol sites created
• Substantial improvement
EAC09–010
Limb Prostheses
Myoelectric Control Example (Movie)
EAC09–011
Jesse Sullivan video (Available on YouTube.com)
Limb Prostheses
(Click on black edge): “bionic_arm_BB.wmv”
Recent Limb Prosthetics Efforts• Major current effort by U.S. military to improve
prosthetic limbs– Improved myoelectric controls– Embedded neural-/myo-sensors for control/sensation– Directly connect limb to bone
EAC09–012
Limb Prostheses
1) See file: “CNN Tech 08-05-16 Hand To Amputees.flv”
2) See file: “DARPA's Bionic Arm.flv”
Both videos from YouTube.com
EMG Testing Simulator• 2010 WPI senior project (Jung, Meklenburg, Patrick)
• Emulates EMG signal. Used as testing input to new prosthesis, prosthesis under repair.
EAC10–012a
Limb Prostheses
(Click on photo)
Some Lower-Limb Prosthesis Research
• Hugh Herr, MIT
• Variable damper knee prosthesis– See file “knee.ram”
EAC09–013
Rehab: MIT-MANUS• CompliantCompliant wrist,
elbow rehab robot
EAC10–016a
See file: “CNN 14 May 2006.mpg”• Developing
ankle robot
Sroke/TBI Rehabilitation
From MIT Newman Lab
(Click just below in white)
Steve Bitar Heartbeat Monitor Lab• Phototransistor monitors finger pulse
pressure (photoplethysmogram—PPG)
• Simple lab used in WPI ECE, etc.• See: http://ece.wpi.edu/~sjbitar/Project_Pulse_Kit/
EAC10–100
Bitar Heartbeat Monitor Lab (2)
• If oscilloscope is used, only require:– R1, R2, LED1, Q1, 9 V battery
EAC10–101
Bitar Heartbeat Monitor Lab (3)• Hold finger over LED, monitor collector of Q1
EAC10–102
DC coupled, low gain AC coupled, high gain
Active Research in Limb Prostheses• Walter Reed Hospital, Military Amputee Research Program (MARP)
• [http://www.tatrc.org/prosthetics] [http://www.tatrc.org/portfolios.html#advanced_prosthetics] “Advanced Prosthetics and Human Performance” Portfolio; Telemedicine and Advanced Technology Research Center (TATRC) , U.S. Army Medical Research and Materiel Command
• [http://www.ninds.nih.gov/research/npp/resources/] National Institutes of Health (NIH), National Institute of Neurological Disorders and Stroke (NINDS), “Neural Interfaces Resources & Contracts” web page
• [http://www.darpa.mil/dso/thrusts/bio/restbio_tech/revprost/index.htm] “Revolutionizing Prosthetics” Program, Defense Advanced Research Projects Agency (DARPA)
• [http://www.jhuapl.edu/newscenter/pressreleases/2007/070426.asp] April 2007 update on the work of John’s Hopkins researchers on the DARPA “Revolutionizing Prosthetics” project
EAC09–017