Transcript Wireless Mobile EKG - School of Electrical and Computer

A Mobile Wireless
Electrocardiogram System
for Health Care Facilities
John Farner
Jason Fritts
Julian Jaeger
Joe Richard
Georgia Institute of Technology
School of Electrical and Computer Engineering
Project Overview
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A mobile wireless EKG system that will track and
store heart rhythm data, allow patients freedom
of movement, and communicate with a central
base station
Marketed to hospitals, nursing homes, and other
health facilities to assist medical staff and
increase patient care quality
Provide a reasonable alternative to conventional
EKG systems at a reduced cost
Design Objectives
Safe for user
 Reliable EKG data under a variety of
circumstances
 Base station interface
 Easy to use mobile system
 Lightweight and small size
 Long range wireless data transfer
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Two Stage Implementation
Stage 1:
Measuring Potential
Across the Human Body
Average
Men:
Heartbeat
70 bpm
Women:
Up
75 bpm
to 200 bpm Exercising
Chest
Voltage, 0.5 mV to 5.0 mV
Front End Circuitry
AD624AD
Precision Instrumentation Amplifier
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Programmable gain
between 1 and 1000
CMRR exceeds 110
dB when the gain is
set to 1000
http://www.ortodoxism.ro/datasheets/analogdevices/AD624BD.pdf
Linear Bandpass Filter
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No battery power
consumption
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Loss of half the
signal strength during testing
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Bandwidth ≈ 1 Hz – 20 Hz
Linear Bandpass Filter Bode Plot
Reducing Input Signal Noise
Before Filter
http://www.analog.com/library/analogDialogue/archives/37-11/ecg.html
After Filter
Stage 2:
EKG Data Acquisition
USB
http://robot.lonningdal.net/parts/phidgets.jpg
http://f.ipc2u.ru/files/products/34462/ebox2300.jpg
A Phidgets voltage sensor gathers data from the output of the front
end circuitry
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An onboard ADC converts analog signal to digital values
A C# OS subproject stores the digital data for later transmission to the
base station
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Mobile System Software
Start
Gather initial analog
input values
Store digitally as Y0
Initialize timer
Store time as X0
Event
Handling
Have analog
inputs changed?
YES
Read analog input
Store digitally as Yi
Read system time
Store time as Xi
NO
NO
Has timer
reached 5 sec?
YES
Run a second
timer to wait 5 min
between EKG
readings
Wireless Communication
http://www.embeddedpc.net/Portals/6/WiFi_Option.jpg
http://z.about.com/d/compnetworking/1/0/q/3/linksys_wrt54g.jpg
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Files shared using Windows CE filesharing on a local area network.
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eBOX uses a mini PCI 802.11g WiFi card
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Base station connected to a Linksys 802.11g WiFi router
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802.11g WiFi Standard
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Provides sufficient range (up to 38 meters)
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Provides data transfer rate of 54 Mbps
Base Station GUI
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Select patient from
drop-down menu
Patient’s information
is displayed in text
boxes
Select desired heart
data from list box to
be graphed
Design Choices
Advantages
Disadvantages
Amplifier
- Single component
- 1K amplification
- Precision measurement
- Power consumption
- Cost
Isolation
- Patient safety
- Low cost solution
- Less robust design
Filtering
- No battery power
consumption
- Signal attenuation
Phidgets
- Ease of use
- Onboard ADC
- Low sensor sampling rate
eBOX
- Ease of use
- Power consumption
- Built in wireless capabilities
Wi-Fi
- Cost
- Ease of installation
- Cell phone modem gives
longer range
Project Timeline
Integration of Two
October 22
Stages
Complete Wi-Fi data
October 31
transmission
Final Computer Interface
November 7
Software
Packaging November 28
Testing and Tweaking December 3
Final Presentation December 5
Future Work
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Integration of stage 1 and stage 2
Data transfer
 Connection between eBOX and base station
 Automated file sharing
Mobile power options:
 Use a 2nd voltage regulator or voltage supply
 Use a 5V rail voltage
Packaging for mobility
“This year an estimated 1.2 million Americans will have
a new or recurrent coronary attack.”
http://www.americanheart.org/presenter.jhtml?identifier=4478