This project focuses on the development of the ECG component that is capable of capturing the ECG signal from human body. In ECG measurement portion, sensing bio electric potential is necessary. For this electrodes were used. Figure 6 shows the 3M Red Dot Repositionable Electrodes that were used in this project.
The 3M Red Dot Repositionable Electrode is comfortable and breathable with a soft cloth backing, therefore they are conformable to skin contours. Red Dot Repositionable Electrodes reduce artifact, and may offer time and cost savings. The entire surface of the electrode is conductive, resulting in a low impedance electrode. For adhesive we used ECG jelly (STERIMED) which is non irritating to skin, has neutral pH and high conductivity.
The ECG signal from the body was amplified using instrumentation amplifier (AD620). AD620 is the bio-potential amplifier used in the system. It has gain range of 1 to 1000, low power, common Mode Rejection Ratio (CMMR) greater than 100dB. It requires only a single external gain setting resistor Rg. The signal after amplification was filtered through Low Pass Filter (LPF), followed by High Pass Filter (HPF) and lastly Notch filter. For the design of these filter, various combination of resistor and capacitor were used using operational amplifier (TL074CN). It is a quad J-fet operational amplifier with low power consumption and wide CMMR. The Filtered ECG signal was then viewed in computer using Sound Oscilloscope (C. Zeitnitz). The stress to the heart is given through motorized Treadmill Machine (WNQ) as shown in Figure 7.
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