A Mobile Wireless Electrocardiogram System for Health Care Facilities

1
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
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Project Overview

• 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

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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
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Stage 1Measuring Potential Across the Human Body

• Average Heartbeat
• Men 70 bpm
• Women 75 bpm
• Up to 200 bpm Exercising
• Chest Voltage, 0.5 mV to 5.0 mV

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Front End Circuitry
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AD624ADPrecision Instrumentation Amplifier

• 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
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Linear Bandpass Filter

• No battery power consumption
• Loss of half the signal strength during testing
• Bandwidth 1 Hz 20 Hz

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Linear Bandpass Filter Bode Plot
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Reducing Input Signal Noise
Before Filter
After Filter
http//www.analog.com/library/analogDialogue/archi
ves/37-11/ecg.html
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Stage 2EKG Data Acquisition
USB
http//f.ipc2u.ru/files/products/34462/ebox2300.jp
g
http//robot.lonningdal.net/parts/phidgets.jpg

• A Phidgets voltage sensor gathers data from the
  output of the front end circuitry
• 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
Gather initial analog input values Store
digitally as Y0
Start
Initialize timer Store time as X0
Event Handling
Have analog inputs changed?
Has timer reached 5 sec?
NO
NO
YES
YES
Read analog input Store digitally as Yi
Run a second timer to wait 5 min between EKG
readings
Read system time Store time as Xi
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Wireless Communication
http//z.about.com/d/compnetworking/1/0/q/3/linksy
s_wrt54g.jpg
http//www.embeddedpc.net/Portals/6/WiFi_Option.jp
g

• Files shared using Windows CE filesharing on a
  local area network.
• eBOX uses a mini PCI 802.11g WiFi card
• Base station connected to a Linksys 802.11g WiFi
  router
• 802.11g WiFi Standard
• Provides sufficient range (up to 38 meters)
• Provides data transfer rate of 54 Mbps

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Base Station GUI

• Select patient from drop-down menu
• Patients information is displayed in text boxes
• Select desired heart data from list box to be
  graphed

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Design Choices
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Project Timeline
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Future Work

• 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

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• This year an estimated 1.2 million Americans
  will have a new or recurrent coronary attack.

http//www.americanheart.org/presenter.jhtml?ident
ifier4478