The budget for smart ECG machine.

A budget is quantified financial plan and it is an important factor to realise this project objectives. A cost estimate is used to establish a project budget. In this project he list of components and estimation budget is state as below:

ü  Electrode lead for bio-potential

ü  AD620 for instrumentation amplifier (with by pass capacitor)

ü  LM 358 as a Low Pass Filter (additional fixed amplification).

ü  LM 311 as voltage comparator (to measure analog signal to interface with digital logic)

ü  CMOS (Digital to analog converter)

ü  PIC 16F84A (generate 256 different voltage level between 0V – 5V).

ü  Use of Elexol USB MOD3 to interface in PC.

PIC 16F84A

There are various version of Elexol USBMOD which is USB MOD1, USB MOD2, USB MOD3, USB MOD4 and USB MOD5. In this project the low-cost integrated module in USB MOD3 for transferring serial data over USB is match which project requirement. Based on the FTDI FT232BM USB UART IC, the USBMOD3 is capable of transfer rates of up to 1000k baud (RS232) and 3000k baud. Unlike the previous version of USB MOD1 and USB MOD2 which is not meet the project’s requirement. Meanwhile, the USB MOD4 and USB MOD5 are expensive (high cost) because it is much advance with the bidirectional data transfer can be switched between FIFO interface modes with high baud of transfer rate. 

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. 

Problem statement for smart ECG machine.

A problem statement is a concise description of the issues that need to be addressed by a problem solving team and should be presented to them (or created by them) before they try to solve the problem. When bringing together a team to achieve a particular purpose, provide them with a problem statement.

For this project, we notice that cardiovascular disease is the number one cause of death in Malaysia for both among men and women. Therefore it is very important to early recognise the signs of a heart attack and immediately seek for medical attention. In this research study, this project will identify the weaknesses of the existing ECG and eliminates them. The major problem when we try to create an ECG circuit is the baseline is not stable and thus creating noise. The correct method to amplify and filter signal discovered to rectify this situation.

The ECG is an important device yet it still produces noise which can distort the original waveform, leading to an inaccurate signal waveform. This inaccurate signal is not good for the analysis of the patient’s condition where it may signify the patient has a slightly better or worse condition. Moreover, the existing ECG machine is high cost and most of people can not afford to have it which leads to unable to self monitor their own electrical activity of the heart. Therefore the proposed ECG tries to work out this predicament and it also resolves the problems in amplifying signal by selecting the best components.

In education field, medical engineering students don’t have the opportunity to operate the internal structure of medical devices due to its cost. They are often to study and analyse about the output which came from the machine rather than to handle and recognize the internal structure of medical device. Students are not familiar with components inside the machine which result lack of confident level to repair it because of the loss of practical wisdom. Hence, development of this smart ECG machine will give the opportunity for student to have their own ECG kit. Through all the advantages related to this research, this project is very useful for educational purposes. 

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 =)

The important of ECG monitoring.

Why I choose smart ECG machine for my final year project (FYP)?

The electrocardiogram (ECG or EKG) is a diagnostic tool that measures and records the electrical activity of the heart in exquisite detail over time by means of capturing and recording it externally by skin electrodes. Research has shown that regular ECG based heart screening significantly reduces the risk of sudden cardiac death. Meanwhile, as for the education view, this smart and portable ECG device is a gateway to better understanding of the heart's electrical patterns and to overcome a problem which is most of the students can not afford to own it or to do self practical.

With this smart ECG machine, heart readings can be taken any time symptoms appear, from anywhere including at home, the office, the gym, or in remote areas which are currently inaccessible to the common ECG machines found in hospitals and clinics. "How about the cost??" You don't have to worry about the price tag because I will make sure it is affordable. "Cool !!"

Are you still curious about this project?? Keep calm and stay tune because I will share and post more on how to build it by your own. Hence, we can DIY (do it yourself) together!! =)