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

Front End Circuitry

AD624AD Precision Instrumentation Amplifier Programmable gain between 1 and 1000 CMRR exceeds 110 dB when the gain is set to

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

Stage 2: EKG Data Acquisition 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 Software Start Gather initial analog input values Store digitally as Y 0 Initialize timer Store time as X 0 Have analog inputs changed? Has timer reached 5 sec? NO Read system time Store time as X i Read analog input Store digitally as Y i YES Run a second timer to wait 5 min between EKG readings Event Handling NO

Wireless Communication Files shared using Windows CE filesharing on a local area network. eBOX uses a mini PCI g WiFi card Base station connected to a Linksys g WiFi router g 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 Choices AdvantagesDisadvantages 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 PackagingNovember 28 Testing and TweakingDecember 3 Final PresentationDecember 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 2 nd 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.”