Development of Three Lead ECG Machine

Abstract

An ECG device is used to monitor and analyze the heart activity. In this three lead ECG machine project, we have designed a hardware module for observing ECG signal. The main advantage of constructing a three lead ECG machine is taking measurement during transportation of the patient. The three lead ECG machine requires only patients’ limbs to take readings not whole chest area like in 12-lead ECG machine. Although in three lead ECG machine we can observe only two sides of human heart i.e. lateral side and inferior side of the heart. In an ECG machine construction various hardware component needed such as instrumentation amplifier, 741 OPAMP, electrodes, analog to digital conversion (ADC) module, filtering module and display module etc. The task of collecting various heart signals through the limbs of the patients’ is done using electrodes. It could be clamp electrode, adhesive electrode, patch electrode etc. The signals Collected through electrodes are fed to the instrumentation amplifier which basically is a differential amplifier, gets the ECG signals of millivolts from body and amplifies them with internal gain then passes them to filtering circuit for noise removal and setting the upper and lower frequency limitations on the ECG frequency. The signal obtained after the filtering is then again subjected to a gain amplifier for amplifying the final output ECG signals. The other artifact which influence the ECG signals like frequency distortion, naked wire, power line artifact, environmental problems are taken care for obtaining a good and useful ecg signal using which medical officer can do the analysis of the patients’ heart