ELECTROCARDIOGRAM MONITORING WIRELESS LAN ECG

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ELECTROCARDIOGRAM MONITORING USINGWIRELESS LAN ECG

rA,rhmad fu zalr, Jondri:

'Biomedical Signal Processing & Instrumentation Research croup (BioSpIN)Electrical & Communication Faculty, Telkom Institute ofTechnologyJl lelekomunikasi no l. Ters. Brah Baru. Bandung. [email protected]

'Compurarional Science Re.earch Croup (CSRG)Science Faculty, Telkom Institute of Technology

J! Telekomunikasi no 1, Ters. Buah Baru, Bandung, [email protected]

1. Introduction

Electrocardiograrn (ECG) is a physiologicat signat produced by elecrrical acrivity ofheart.ECC is recorded using electrocardiogmph device. There are three types of electocardiographd€vice, categorized by djffereni puryoses olthe ECG measuremenr. Standard clinicai ECG uses t2eleclrodes and paper chari to represent ECG signrl. Monitoring ECG uses I or 2 electrodes and acarhod€ my tube (CRT) to display rhe signals. ln monitorins ECG. parielrt,s ECG is recorded for acenain period to observe patient's heart condition. Somerimes, patie;t should be exanjned in other.oom so monitoring ECC will be interrupted because the ECG device can not be moved

To solve problem mention beforq this paper proposes a design of portable ECG deviceconnected with wireless data transmission module. Using portable device, if patient has to move to3nother room for other examination, monitoring ECG srill can be conducted. It is made possible by$e use ,rf Wireless Local Area Network (LAN) 8C2.l lb, chosen for dala transmission because802.1lb protocol is common ir Indonesia. For some computer, 802.t lb devices is embedded, rhatallows PC or notebook 10 receive rhe data wirhout addirional devices. By transmitting ECG data thatwiil be received by server, patient's ECG could be monitored every rime even thJpatient mobiletbrm one room to another room,

2. The ECG

ECC signal has voltage up to 5 mV and frequency from 0.j Hz until 100 Hz. ECC signalhas specific wavefom, therefore it can be used to indicale the health of the heart. ECG signi isFcorded using electrocardiograph. ECG rvavelorrn has seveial components such as: p wave, Rlcave, QRS complex, T wave, P-R intervai, and R-T inrerval. Each compon€nt of ECG indicatesspecific activity of human heart. The relationship behreen ECG wavefom with cardiac activity isx follow:

a. P wave is the elect cal waveform that is caused by atrial contractioq i.e. the portion oftheECG tracing that represents depoladzation of the atrial myocardium. lnitial ponion olthe pwave is largely a reflection of right atdal depolarization, a]ld the terminal portion rcflectsdepolarization ofthe left afium.

b. R wave is a portion of the ECG that represents the end of aftial contmction and thebeginning of venticular contraction.

c. QRS complex is a portion of tbe EKG facing that rcpresents depolarization of thev€ntricular myocardium. Normally the ventricles are activated simultan€ously

d. T wave is a portion ofihe ECG that represents ventricular repolarizatione. PR interval: time interval from onset of atial depolarization (p wave) to onset of

ventdcular depolarization (QRS cornplex)

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A normal ECG aveform can be seen 3t figur€ l 'l

is ihe time at whicb ih€ e$ireplateau Phase of ihe ventricular

--T- R R intltlal

Fjgule l: A Nonnal ECG

DurationAmplitudeEcc wave

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There are thre€ methods to record ECG waveform l2l:

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3, System Design

Design of proposed Wireless LAN ECG system can be seen at figure 3. ECC signal isrecorded by use a single channel ECG then this signal is tmnsmitted via wireless LAN network tos€lver. At the server, this data will be {ecorded, displayed, and analyzed. The circui! ol singlechannel ECG can be seen at figure 4.

F;gure J: Wireless LAN ECO system

Single Channel ECG

Figure 4: Single Channel ECG System wirh Wireless LAN Module

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ECG signal is captured using electrode then it is amplified using bio-porentiat amplifier. Band passEher (BPF) is used to limit signal h 0.5-40 Hz to remove low frequency noise aid 50Hz power lineinteference. Low pass filter (LPF) is used to limjt ECG signal under 20H2. Adder will mise volt gelevel up to I volt to make ECG signal level suitable as input of aralog digital converter (ADC).Analog process ofECG signal v/ill produce signal wiihin 0.5-20 Hz and 0-4 Volt. Figue 5(a) andFigure 5(b) show bio-potential amplifier circ it and BPF circuir respectively.

(a) (b)

Figure 5: (a) Bio"potential &rylifier[4] (b) BPF 0.5 -40 Hz

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Digital Block and Wireless LAN Modul€

Digital sLrbsystem consisls of 0804 analog to digitai converter, AT89C51 microcontroLler,

and serial communication RS323. Circril ofwireless LAN ECG digjtal subsystem cdn be sccn inFigu.e 6.

Figure 6: Digital subsystem

This design uses wiz610wi, embedded wireless LAN module from WIZ'.lET@l6l as

traDsmilter module. This nodule works to cha,]ge serial data communication to ,trele.ts LAN802.1i b standard dat3 packet. This module has processor, dala memory, 802.1lb lansceiver, and

serial co neciion w;th marimum data rate 230.400 bps. This module can be connected to Pc/laptopwithout access point. To connect the module wiih digilal ECG, we connect data output of RS232

wilh pin number 2 DB9 ofWiz610wi.

Mor toritrg ECG SoftwareThe software was developed using Borlard Delphi 7. Gererally, this software will check

whether data transmitted by wlieless LAN module exist. After the ECG data alc rcceived, ECC data

will be displayed at PC nonitot and saved to database.

4. Result & Discussion

Output sigal of bio-potential alnplifier and output signal ofBPF are shown in figure 7(a)and ?(b) respeclively. Figure 7(a) and 7(b) show that EcG signal has higher leveL bul noise is sfillexist. Noise is reduced in LPF output as shown in Figure 8(a) ard si$al ECG received by PC ;s

shollr) in Fisure 8(b).

Figure 7r (a) Bio-potential amplifler output (b) BPF output

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:Cc signal received by PC shorvs that ECG had been transmitted property:: iolerable level. In ECG recording process, patjent,s raouement *uses'-.3refore needs signal processing step io rcduce patient's movement noise,

and noise was reducednoise significantly. It

(a)Figure 8: (a) LPF 20 Hz ourpLrt

5. Conclusion Remark

Wireless LAN ECG device has worked properiy. Signal condjtioning block js able roJnptify ECC signal to level thar can be transmifted by l\,irele; LAN module a|d ttre receiver caa:eceive the tansmitted ECG signat. Some existing problerns are srabiliry of the device and thc;imiiation that one server coulcl access only one d€vice. patient,s mo.r'erlrent produses noise thai:ignificantiy dislurbs the received signal. Special f,ilter is needed ro minimize the noise. Ior nerl:\'ork, we stiil try to malic server that can received ECG folm some devicss simuhancously.

-{cknowledgments

. This.res?ch was tunded by DGHE ofEducational Minisb,y, Repubtic ofindonesiq Crantrumber : 069/SP2Ii/PP/DP2\UIII|2A|O

References

(b)(b) ECG signal received by PC

l[6] as

' LAN

laptopRS2']2

checkG data

r 7(a)

PC is

tlll:ltjl

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New York- 1998

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Stppottet E IEEE ttdatusii Sedb\ IEEE nasfi't rt rnthtusi. JointSocirry (Canoe) rtu{at?sia Ctuptel

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