The main objectives of smart ECG machine.

Objective is really important to aims the project's achievement within a time frame and available resources. It is a basic tools that underlie all planning and methodology. In this project the objectives are as follow : 

O  To investigate and record the electrical activity of the heart (amplify the ECG signal and eliminate or minimise the signal disturbance).

O     To give the opportunity for students to operate their own medical device.

O To increase medical instrumentation knowledge focusing to ECG machine especially for medical engineering students.

O To provide healthy environment and minimize cardiovascular disease.

To achieves all the objectives, there are many factor need to be consider especially the measurement, amplification and noise.

Measurement:

The electrical signals which command cardiac musculature can be detected on the surface of the skin. In theory one could grab the two leads of a standard volt meter, one with each hand, and see the voltage change as their heart beats, but the fluctuations are rapid and by the time these signals reach the skin they are extremely weak (a few millionths of a volt) and difficult to detect with simple devices. Therefore, amplification is needed.

Amplification: 

To amplify the signal, operational amplifier is needed. The gain or the multiplication factor of an op-amp is controlled by varying the resistors attached to it, and an op-amp with a gain of 1000 will take a 1 millivolt signal and amplify it to 1 volt; meaning that it  multiplies the 1 millivolt signal with 1000 to produce 1 volt signal.

There are many different types of microchip op-amps, and they’re often packaged with multiple op-amps in one chip (such as the quad-op-amp lm324, or the dual-op-amp lm358n). Any op-amp designed for low voltage will do for our purposes, and we only need one.

Noise:  

The noise comes from radiation from a variety of things (computers, cell phones, lights, and especially the wiring in your walls) which is absorbed by your skin and is measured with your ECG. The noise also comes from muscle contractions, power line interference 50-60 Hz and electrode contact noise. The traditional method of to eliminate this noise is by using complicated analogue circuitry, but since this noise has a characteristic, repeating, high-frequency wave pattern, it can be separated from the ECG using digital signal processing computer software. Another way is to use a filter. The filter for the ECG application should be a notch filter (high-pass and low-pass filter). It should filter in the range from 0.5 Hz to 50 Hz.