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

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Simple ECG Lead System

From: nurseCE.com

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Electrophysiologic Monitoring

ECG—Electrocardiogram

• Electrical activity of the heart

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Electrophysiologic Monitoring

ECG Arrhythmias

• Abnormal rates (fast, slow, varied, notnot varied!)

• Abnormal shapes

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www.physionet.org

Electrophysiologic Monitoring

Measuring Respiration from ECG

• Respiration modulates the ECG!

• Many more direct measures– Chest band, capnograph (for CO2), chest

impedance

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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

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Healthy

Alternans

Clancy M.S., 1987.

Electrophysiologic Monitoring

Ambulatory Monitors

www.nihonkohden.com

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Monitor abnormal rates, shapes, etc.

ECG, Blood pressure, SaO2, respiration, …

Electrophysiologic Monitoring

EEG—Electroencephalogram

• Electrical activity of the brain

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www.abc.net.au

Electrophysiologic Monitoring

Some Characteristic EEG

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medical-dictionary.thefreedictionary.com

Electrophysiologic Monitoring

Epilepsy• Abnormal brain

discharges– Altered

consciousness, abnormal movement/ sensation, changed behavior

– Seizures

• EEG: Spike discharges

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epilepsygroup.com

Electrophysiologic Monitoring

Motor Unit Decomposition

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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

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Neuro-Prostheses

Cochlear Implants

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www.hearingloss-wa.org www.childrensspecialists.com

Restore Hearing

Neuro-Prostheses

Deep Brain Stimulation

• Reduce tremor in Parkinson’s

• Suppress depression ‒ experimental

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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

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Neuro-Prostheses

Goal: 1970’s “Six Million Dollar Man”

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See file: “sixmilliondollarman.flv”

Limb Prostheses

Video available on YouTube.com

Body-Powered Upper Limbs• Basic concepts date to civil War

medicine

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See file: “Prosthetic Arm Tip #2: Tying a Shoe.flv”

Limb Prostheses

Video available on YouTube.com

EMGamp: Myoelectric Control of Prosthesis

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• 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

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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

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Limb Prostheses

Myoelectric Control Example (Movie)

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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

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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.

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Limb Prostheses

(Click on photo)

Some Lower-Limb Prosthesis Research

• Hugh Herr, MIT

• Variable damper knee prosthesis– See file “knee.ram”

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Rehab: Herr Ankle-Foot Orthosis• Compliant ankle: See file: “AAFO.ram”

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Rehab: MIT-MANUS• CompliantCompliant wrist,

elbow rehab robot

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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/

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Bitar Heartbeat Monitor Lab (2)

• If oscilloscope is used, only require:– R1, R2, LED1, Q1, 9 V battery

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Bitar Heartbeat Monitor Lab (3)• Hold finger over LED, monitor collector of Q1

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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

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