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
Dec 24, 2015
A Mobile Wireless Electrocardiogram System for Health Care Facilities
John FarnerJason Fritts
Julian JaegerJoe Richard
Georgia Institute of Technology
School of Electrical and Computer Engineering
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
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
Two Stage Implementation
Stage 1:Measuring Potential Across the Human BodyAverage Heartbeat
Men: 70 bpm
Women: 75 bpm
Up to 200 bpm Exercising
Chest Voltage, 0.5 mV to 5.0 mV
Front End Circuitry
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
Linear Bandpass Filter
No battery power consumption
Loss of half the signal strength during testing
Bandwidth ≈ 1 Hz – 20 Hz
Linear Bandpass Filter Bode Plot
Reducing Input Signal Noise
Before Filter After Filter
http://www.analog.com/library/analogDialogue/archives/37-11/ecg.html
Stage 2:EKG Data Acquisition
http://robot.lonningdal.net/parts/phidgets.jpghttp://f.ipc2u.ru/files/products/34462/ebox2300.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
USB
Mobile System SoftwareStart
Gather initial analog input values
Store digitally as Y0
Initialize timer
Store time as X0
Have analog inputs changed?
Has timer reached 5 sec?NO
Read system time
Store time as Xi
Read analog input
Store digitally as Yi
YES YES
Run a second timer to wait 5 min between EKG readings
Event Handling
NO
Wireless Communication
http://z.about.com/d/compnetworking/1/0/q/3/linksys_wrt54g.jpghttp://www.embeddedpc.net/Portals/6/WiFi_Option.jpg
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
Base Station GUI
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 ChoicesAdvantages 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
- Built in wireless capabilities
- Power consumption
Wi-Fi- Cost
- Ease of installation- Cell phone modem gives longer range
Project Timeline
Integration of Two Stages
October 22
Complete Wi-Fi data transmission
October 31
Final Computer Interface Software
November 7
Packaging November 28
Testing and Tweaking December 3
Final Presentation December 5
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
“This year an estimated 1.2 million Americans will have a new or recurrent coronary attack.”
http://www.americanheart.org/presenter.jhtml?identifier=4478