The smart ECG working principle.

To design reliability of a project, we need to learn on their block diagram. The block diagram will show us the step to achieve our target (the expected output). Hence, let us look at the block diagram of this project as shown below :

The project block diagram is explained as the bio-potential signal is taken from the wrist of the subject. It is then go through several processes in the ECG circuit before the result could be read. The signal from the body is first amplified by the instrumentation amplifier. The amplification is set to either 2 times or 4 times. It is then filtered by a low pass filter. After that, analogue to digital conversion is done so that the signal could be interfaced to laptop. Using Visual Basic software, a program was created to display the signal generated.

The illustration of the ECG system.

What is bio-potential??

An electric potential that is measured between points in living cells, tissues, and organisms, and which accompanies all biochemical processes.Also describes the transfer of information between and within cells. In this project we will measures the electric activity of the heart.

Why we use instrumentation amplifier?

Potentially combines the best features desirable for bio-potential measurements because it have high differential gain, low common mode gain, high CMRR and high input resistance. Plus, I choose the  instrumentation amplifier because it is simple and cheap, although high-quality OpAmps with high CMRR should be used.

The use of low pass filter. 

By definition, a low-pass filter is a circuit offering easy passage to low-frequency signals and difficult passage to high-frequency signals. As we all know, in this project we need to analyse the low frequency of the heart and we want to eliminate other frequency (high frequency signal) which can disturb the system (signal processing).

What is ADC?

We need to use the analogue-to-digital converter as a device which converts a continuous quantity to a discrete time digital representation. An ADC may also provide an isolated measurement.

The interfacing.

This is performed by using the Elexol USB MOD3. Normally, people would use DAQ data card but due to simplicity, the USB MOD3 is used.

The elexol USB MOD3.

Why I choose Visual Basic?
Visual Basic is relatively easy to learn and use. Visual Basic was derived from BASIC and enables the rapid application development (RAD) of graphical user interface (GUI) applications, access to databases using Data Access Objects, Remote Data Objects, or ActiveX Data Objects, and creation of ActiveX controls and objects. Scripting languages such as VBA and VBScript are syntactically similar to Visual Basic, but perform differently. A programmer can put together an application using the components provided with Visual Basic itself. 

Through all the explanation I hope that all of you understand on how this project is going to work. At the end of this project, we will display the output through the screen of the laptop. Until then, see you again in my next post. Take care. Assalamualaikum =)