Published on

IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit

  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide


  1. 1. Shukla, Vandana Pandya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 4, June-July 2012, pp.842-846 Open Hardware Platform For Reconstruction Of ECG Signal Deepali Shukla1 (Asst.Professor), Vandana Pandya2 (Asst.Professor) Medicaps Institute of Technology & Management, Indore (M.P.), IndiaAbstract At present the heart disease is one of the heart that depicts the cardiac cycle. It is routinelyserious disease that may threaten human life. The used as a first course of choice in diagnosing manyelectrocardiogram is important role in the cardiovascular diseases [7].prevention, diagnosis the abnormality of patients& rescue of heart disease. An ECG is used to A. ECG Measurementmeasure the electrical activity of the heart treated The potential created by the heart wallas a vector quantity. It measures the rate and contraction spreads electrical currents from the heartregularity of heartbeats. The goal of this project is throughout the body. The spreading electricalto develop a device classified as a “Open hardware currents create different potentials at different pointsplatform for reconstruction of ECG signal ”.A on the body. Leads are placed on the body in severalremote device is attached to the person being pre-determined locations to provide informationmonitored. The remote device acquires the raw about heart conditions. The cardiac signal, typically 5ECG data from the Leads which are placed in mV peak to peak, is an AC signal with a bandwidthpredefined areas of the body. In this paper three of 0.05 Hz to 50 Hzlead ECG monitor system is present, which can be .used for measurement & recording of human The Three Lead ECGelectrocardiogram. ATMEL Atmega8 AVR series The electrical activity can be represented asmicrocontroller is the heart of system which is in a dipole (a vector between two point charges). Thethe Severnio board. The ECG signal from the placement of the electrodes on the body determinesbody is amplified and filtered by the the view of the vector as a function of time[1]. Figureinstrumentation amplifier. Sevrenio is an open 1 represents the most basic form of the electrodehardware, Bluetooth wireless communication, placement which is based on Einthoven’s triangle.single microcontroller, multiple I/O platforms, This theoretical triangle is drawn around the heartused in this project to interface our with each apex of the triangle representing where theelectrocardiogram Signal conditioning circuit to fluids.the PC. Necessary filter requirements (for ECG Around the heart connect electrically withfrequency band selection) and formatting of the limbs. Lead I measure the differential potentialfiltered ECG data (for transmission) both occur in between the right and left arms, Lead II between thethe Severnio board in which AVR microcontroller right arm and left leg, and Lead III between the leftis present. A second Data acquisition unit is arm and left leg.connected to Serial port of a P.C. The data is thentransmitted via the serial port to the P.C fordisplay. A user friendly graphical interface (GUI)was constructed using Visual Basic 6.0 enterpriseedition. The GUI allows for the monitoring of realtime ECG data. A database was implementedusing MS Access 2000. This allowed for storage ofthe ECG data.Key Words: Open Hardware ECG, Electrodes,Severnio Board, Serial cable, PC.INTRODUCTION Cardiac disease is one of the most dangerous Figure 1: The Three Leadsthreats to human health. Moreover, due to the Einthoven’s law also states that the value of any pointproblem of aging of population is getting worse and of the triangle can be computed as long as values forworse, the number of cardiac deaths is sustained the other two points are known [1]. The Einthovenincreasing [6]. ECG diagnosis has the advantages of limb leads (standard leads) are defined in the Figureconvenience, precision and low-cost, and thereforeECG diagnosis has been widely used nowadays. Anelectrocardiogram (ECG) is an electrical recording of 842 | P a g e
  2. 2. Shukla, Vandana Pandya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 4, June-July 2012, pp.842-846SYSTEM FUNCTIONALITY into three sections. The section A works as a voltageECG Design follower of the two input signals, the circuit has a The heart electric signal has a very small high input impedance and can be connected to otheramplitude (around1mV) and is immersed into other devices or human signals without changing the shapegreater signals produced by the body. To be able to of the signal to be measured. The section B is ameasure the heart signals, first they must be differential amplifier, it takes the difference betweenamplified and filtered form those we are not the two input signals and multiplies it times a factor.interested in. If the goal is to digitize the ECG signal Basically this ECG system takes the differencethe frequencies of the heart signal goes from 0.05Hz between the two voltages measured in both armsto 100Hz, first the frequencies out of that range must having as a reference voltage that measured in onebe minimized and then they should pass through a leg. In the figure, the inputs labeled as VRA andstage of amplification, later, the resulting signal has VLA represent the Voltage of the Right Arm and theto be Manipulated so it can be in the range of 0-5V in Voltage of the Left Arm, respectively, while the VLLorder to be digitized. input represents the Voltage of the Left Leg acting as A. Signal Acquisition a reference of the bioelectric potentials. The ECGThe circuit used for acquire the heart signal is an electrodes should be connected in the inner part ofinstrumentation amplifier (figure 3) which is divided the left ankle and both wrists. Figure 2: Three Leads Calculations The Operational Amplifiers (Opamps) used greater than 100Hz do not belong to heart signals,are built with the JFET technology (TL084), hence additionally, when the frequencies lower than 0.05Hzthey have a high input impedance and need a very are filtered, we eliminate the difference of potentialsmall polarization current, giving an electrical safety between the electrodes and the skin surface that canmargin for the patient. With the configuration shown reach levels up to 300mV and may saturate thein the figure 3, the gain of amplifier is given by amplification devices. In the circuit used toA= (1+2R1/R2)* (R7/R4) implement the Anti Aliasing low pass filter (figure The section C is Anti aliasing low pass 3C).The filter is a simple low pass filter; its job is tofilter, its job is to remove electrical noise picked up remove electrical noise picked up from fluorescentfrom fluorescent lights, computers and AC power lights, computers and AC power lines. ECG haslines. When ECG is amplified the noise is amplified amplitude of only about mV, so to detect it antoo & after swaps the ECG signal. Luckily, the amplifier is needed. There is a problem throughnoised is usually of a higher frequency than the ECG electrical noise or electromagnetic interference.this noise can be reduced by low pass filter. Theamplifier takes input from self sticking electrodes HARDWARE DESIGNthat are attached to the body of the subject whose A. Instrumentation AmplifierECG is being taken. It is important for the cables The instrumentation amplifier is generallyconnecting the electrodes to the inputs of the circuit used for this purpose. The instrumentation amplifierto be as short as possible. is a type of differential amplifier that has been outfitted with input buffers which eliminate the need B. Anti Aliasing low pass filter for input impedance matching and thus make the The next step is anti aliasing filter that amplifier particularly suitable for use in measurementensures that the resulting signal contains only and test equipment. The instrumentation amplifier isfrequencies from 0.05Hz to100Hz[1]. Frequencies useful for amplifying small differential signal which 843 | P a g e
  3. 3. Shukla, Vandana Pandya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 4, June-July 2012, pp.842-846may be riding n high common mode voltage levels. signals in mili-volt range which is supplied from aThis amplifier is particularly useful in amplifying high A B CFigure 3: Circuit Diagram of ECGimpedance source. Additional characteristics includes Severnio Interfaces to digitize and introduce the ECGvery low DC offset, low drift, low noise, very high signal to the computer via a Bluetooth wirelessinput impedance. connection. This system uses AVR microcontroller AT mega 8 as its brain. Eight channel ADC receivesB. Severnio Board analog signal from ECG circuit and convert the data The hardware design is based on an in to digital signal.embedded system implementation using ATMega8AVR microcontroller within Severino Board. This SOFTWARE DESIGNwas used to verify the various ideas and the The ECG signal’s bandwidth is 100Hz, sorequirements for final system design. according with the Nyquist’s theorem; the minimum required sampling frequency is 200Hz. The program is sampling with at 250Hz which is a sufficiently large frequency for acquiring the ECG signal. The software consist of a Standard programming language & boot loader that runs on the board. Software for the microcontroller is designed in C language. Before writing a program, modes of serial communication are decided, baud rate is selected. & Take 100samples/sec. the microcontroller is programmed in following way:Figure 4: Severnio Board 844 | P a g e
  4. 4. Shukla, Vandana Pandya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 4, June-July 2012, pp.842-846Figure 5: Severnio SoftwareCounter can be clock internally by the prescalar.The prescalar is set by clock select bit CS20, CS21, CS22 equal to one.Set counter value in Timer/Counter register 2.Mask the AS2 bit in asynchronous status registerWhen AS2 is written to zero, Timer/Counter 2 is clocked from the I/O clock, clkI/O.In Timer/Counter mask registerOCIE2: Timer/Counter2 Output Compare Match InterruptTimer/Counter2 Compare Match interrupt is disabled.TOIE2: Timer/Counter2 Overflow Interrupt EnableTimer/Counter2 Overflow interrupt is enabled.RESULT The design was successfully dissected into various modules. Each module with has been implemented.The integration of the individual modules was achieved successfully. All the GUI functionality discussed in thereport is operational.The ECG signal can be sampled and analyzed in real-time.The ECG data also can storage in SQL Database and transport the data to PC via Serial cable.The storage of ECG data to the database has been implemented successfully.The system consist of two section1. Hardware Section2. Software SectionHardware Section: ECG signals captured by Electrodes are processed and filtered by signal conditioning block.Now Filtered signals are given to MCU Board.Microcontroller has in inbuilt 10-bit analog to digital converter, which convert analog signal coming fromhuman body(Amplified by instrumentation amplifier) into digital signal .Microcontroller is capturing 200 samples in one sec. from analog pin 845 | P a g e
  5. 5. Shukla, Vandana Pandya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 4, June-July 2012, pp.842-846Figure 6: ECG graphSoftware Section: REFERENCES  Received 200 samples(contain digital values [1] Anwar Vahed ”3-Lead Wireless ECG”. ) now stored in data base. [2] Ramakant Gaikwad “Opamp and LinearVB code used stored data from database and plot Integrated Circuits”,Pearson Education, 4thECG waveform. In the figures 6 the plot of the data Edition,p-p 1-247.stored in the *.dat file after digitalizing and filtering [3] Alejandro Romero, Carely Heras, Miriamthe signal. Vega, Javier Naranjo, Carlos Vázquez, Arturo Preciado,”Intelligent Open –Hardware ECGCONCLUSION Platform for the heart Patients Control and The implementation of the proposed system Diagnosis”.is entirely feasible, especially in those developing [4] Ghongade, R. and Ghatol, A.A.; A briefcountries that have serious delays in the health performance evaluation of ECG featuresystems, because the cost of an ECG study will extraction techniques for artificial neuralinevitably decrease making the study reachable for network based classification, TENCON 2007,most of the population. IEEE Region 10 Conference Oct. 30 2007- As future work, one important Nov. 2 2007 p.p. 1 – 4.characteristics of the heart disease detection system is [5] Ms. Kanwade A. B., Prof. Dr. Patil S. P., Prof.that after some modifications, it can work as a mobile Dr. Bormane D.S. :“ Wireless ECGdevice, making the patient able to be almost in every monitoring system”.place in the planet and still know his heart status. The [6] Shi Zhang, Jinshuan Zhao, Lihuang She, andpatient would use our GSM system with a computer Guohua Wang:” A Novel Pocket Intelligentthat receives the signal and then sends the data to a One Lead ECG Monitorweb server, in which the analysis is done. Once the Based on Fingers Touching”.web server gets the analysis results, they can be sent [7] Tanveer Syeda-Mahmood, David Beymer, andback to the patient along with some medical Fei Wang “Shape-based Matching of ECGrecommendations. Recordings” 846 | P a g e