FYP Week 10 - BP research and troubleshooting

Hello peeps,
  

A very Good Morning everyone... It's a beautiful Friday today...Hope everyone will have a great day!

Part 1: BP research on circuit operation

I have done some reading on the circuit operation of the BP to understand on the basics better. Refer Figure 1 for the block diagram 

 

  Figure 1: BP Block Diagram

From what I have understood, the BP circuit is split into 3 main stages which are the pressure- sensor driving circuit, Oscillometric Pulse measuring circuit and the Half- wave Rectifier circuit. Refer Figure 2, 3, 4 and 5 for the schematic diagram of each stage.

Figure 2 is the driving circuit for the pressure sensor, where in this project I am using the Honeywell SCC02DN pressure sensor of 0 to 5 psi (approx of 0 to 200mmHg)   :)  The pressure sensor connection is shown in Figure 2 and is labeled in a box/ square.

 Figure 2: 1st stage of pressure- sensor driving circuit

  Figure 3: 2nd stage of  Oscillometric Pulse measuring circuit

  Figure 4: 3rd stage of Half-wave Rectifier circuit

Figure 5, indicates the fully combined circuit of the BP stages from stage 1 to stage 3. It shows, how the circuit begins with the sensor driving circuit and how the signal flows from High Pass Filter (HPF) to Low Pass Filter (LPF) and finally to the rectifier circuit  :)

Figure 5: Combined stages

Part 2: BP construction and troubleshooting

After doing some research and troubleshooting the previous BP circuit, I have come to a decision to slightly modify the BP circuit into a more simplified version......  :D  Later, this BP PCB will be connected to the PIC main board for further testing and troubleshooting. Hopefully it works....hehe

As you can see in Figure 6, this BP circuit is much smaller and compact. However, in order to know whether it works or not, I have to burn the program into the PIC first. Meanwhile, have a look below, to see my masterpiece.. hahaha....!

Figure 6: PCB for BP

From Figure 7, you can see that I'm done with the component placement and soldering. Really sorry for the bad soldering....haha... I really don't have talent in soldering...wink2..   ('.' )v

Figure 7: back view of the PCB

No kidding that this BP circuit is difficult to design and I really hope that this circuit could work. So, now all is left is the Heart rate PCB. Next week I will show my progress on the Heart rate PCB. Till then hope you guys could patiently wait for me....

That's it for today...Going to Pasar Road tomorrow to buy some components for the Heart rate PCB construction...I'll try my best to finish the Heart rate circuit by next week.. See you guys soon..Take care  :)

with lots of luv <3, XOXO

Bye2

 

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Quote of the day,

The first and greatest victory is to conquer yourself; to be conquered by yourself is of all things most shameful and vile.  ~Plato 

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Regards,

Idriah Safriza

FYP Week 9 - MAX232 and BP troubleshooting

Konichiwa,

Happy Friday to everyone....! Hope everyone is having a great day today.. Lalala I seriously cant sleep and decided that I should update my blog... hehe... I'm really trying hard and giving my very best to update this blog so that I will not disappoint my followers and viewers.... 

 >>>  Specially just for my FANS.....! Enjoy today's entry and Hope you like it... :D    <<<

Part 1: Assembled circuits

So far, I am done with the drilling and soldering for the Blood Pressure PCB, but I still have trouble to produce a good output with the BP board. So, it is still under further construction and troubleshooting.... Secondly, I have also tried combining all circuits that I have made into one combined/ single unit..... refer Figure 1   :)

Figure 1: Combined schematic diagram

Just for an overall overview of the "Home Patient Monitor" project:

The main circuits used are:

1) PIC main board

2) Heart rate circuit using LDR

3) Blood pressure circuit (for signal filtering and amplification)

4) Body temperature circuit using LM35

5) Power supply for the PIC main board

6) Power supply for the DC motor

Others:

7) DC motor

8) Max232

9) Relay switch circuit

10) LCD

11) switch buttons (3 switches) 

So far, everything is done except for Blood Pressure circuit... I am still troubleshooting the BP circuit as it does not work as it suppose to...  sob2 sad :(   The BP circuit took a much longer time than expected. Once it is done, I will reveal the PCB board okay :)  Now, lets look at the inputs and outputs circuit of this project.

The inputs are:

1) LM35

2) LDR

3) Blood pressure

The outputs are:

1) LCD

2) Computer monitor (Visual Basic)

This week I emphasize work more on the BP circuit troubleshooting and the construction of the MAX232 circuit for interfacing purposes.

Interfacing circuit used:

1) MAX232

2) USB converter cable

Part 2: What is MAX232

 

Figure 2: MAX232 pin configuration 

• The MAX232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signal.

• The drivers provide RS-232 voltage level outputs (approx. ± 7.5 V) from a single + 5 V supply via on-chip charge pumps and external capacitors. This makes it useful for implementing RS-232 in devices that otherwise do not need any voltages outside the 0 V to + 5 V range, as power supply design does not need to be made more complicated just for driving the RS-232 in this case.

• The receivers reduce RS-232 inputs (which may be as high as ± 25 V), to standard 5 V TTL levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V.

• The later MAX232A is backwards compatible with the original MAX232 but may operate at higher baud rates and can use smaller external capacitors – 0.1 μF in place of the 1.0 μF capacitors used with the original device.

It is helpful to understand what occurs to the voltage levels. When a MAX232 IC receives a TTL level to convert, it changes a TTL Logic 0 to between +3 and +15 V, and changes TTL Logic 1 to between -3 to -15 V, and vice versa for converting from RS232 to TTL. This can be confusing when you realize that the RS232 Data Transmission voltages at a certain logic state are opposite from the RS232 Control Line voltages at the same logic state. To clarify the matter, see the table below. For more information see RS-232 Voltage Levels.

RS232 Line Type & Logic Leve	RS232 Voltage	TTL Voltage to/from MAX232
Data Transmission (Rx/Tx) Logic 0	+3 V to +15 V	0 V
Data Transmission (Rx/Tx) Logic 1	-3 V to -15 V	5 V
Control Signals (RTS/CTS/DTR/DSR) Logic 0	-3 V to -15 V	5 V
Control Signals (RTS/CTS/DTR/DSR) Logic 1	+3 V to +15 V	0 V

Source of refference http://en.wikipedia.org/wiki/MAX232

 Figure 3: Connection flow

Part 3: MAX232 Construction

Below, I have attached the components used for the MAX232 circuit construction. Click here for the MAX232 datasheet. For better understanding refer the comparison of MAX220 to MAX249 family here.

 Figure 4: Components used to make the MAX232 for interfacing circuit

 Figure 5: Component placement on the PCB 

As you can see the circuit requires alot of capacitors, this is simply for the noise filtration purposes. Hehe  :p

Figure 6: Component soldering

So, there it is, TADAAAAA......my finished MAX232 circuit...!! That's it for today... Hope u guys enjoy my entry for today.... Wait for my next post okay next week k.... Gonna miss u all.... <3

Bubye peeps.... ('.' )v

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Quote of the day....!

Face what you think you believe and you will be surprised.  ~William Hale White

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Regards,

Idriah Safriza ('.' )k

FYP Week 8 - Omron HEM-7111 (Motor and cuff selection)

Hi,

A very good morning to everyone.... I'm so bored so I decided to update my blog. Yeayyyy blogging time! Okay let's see what to jot down this time...

Hmmm...Recently, I just bought myself an Omron Automatic Blood Pressure Monitor click here for the Omron HEM- 7111 specifications and please refer Figure 1 for the image of the BP set.

Figure 1: Omron Automatic BP Monitor HEM-7111

From my previous post, I've written on the PCB layout for Blood Pressure circuit. So today, I am doing something related to the previous post. I am going to crack open this BP monitor set. Let's see what inside! Refer Figure 2 to see whats in it!

 Figure 2: Take off the cover of the BP set

As you can see in Figure 2, after I take off the cover of the BP set we can clearly see that there are circuits jumble up in the BP box set and it looks messy. So let's look at Figure 3, where I took everything out for a clearer view of the components and circuit. It looks much better after everything is taken out and was arrange nicely.

So, here in Figure 3, we can see the LED screen, the main microcontroller and sensor board (green colour PCB board), the motor set (consist of the tubings, DC motor and solenoid valve), on and off switch button, battery holder and finally the BP box set itself.

Figure 3: Take off everything in the BP set

Now, from Figure 4, we can see the connection between the DC motor, solenoid valve and the tubings for the motor set part only. I put the other stuffs aside as I am not going to use it. The reason I bought the automatic BP set is actually because I need the motor set with all the tubings, the arm cuff and the solenoid valve. 

 Figure 4: DC motor, solenoid valve and other tubing used in the BP set

So now, I will be using this motor set and will try to connect this motor set to a PIC16F877A microcontroller in order to control the BP circuit (Figure 6). Later on, I am thinking of adding another small circuit to the microcontroller board. A relay switch circuit seems reasonable to be use to control the motor, but it is not finalise yet, so I'm still thinking about it whether to use it or not.  :)

As you can see in Figure 5, this is an arm cuff which is normally use together with the BP monitor set. It is use for the Non- Invasive Blood Pressure (NIBP) measurement method. This arm cuff will be connected to the pressure sensor driving circuit. 

Figure 5: Arm cuff (NIBP measurement)

The issue now is that, the sensor that comes together with the automatic BP monitor set (Figure 2) is not suitable to be connected with my new BP circuit (Figure 6). So, I have to find another pressure sensor as replacement. 

 Figure 6: The BP circuit schematic

So that is all for today I guess! Keep in touch and enjoy my entry. Don't forget to follow my blog......peace everyone ('.' )v

Adios peeps...   :)     :p

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jArGoNs UsEd:

non-invasive: when no break in the skin is created and there is no contact with the mucosa, or skin break, or internal body cavity beyond a natural or artificial body orifice. 

invasive procedure: is one which penetrates or breaks the skin or enters a body cavity.

Source taken from http://en.wikipedia.org/wiki/Invasive_%28medical%29 

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QUOTE of the day...!!!

Do what you can, with what you have, where you are.  ~Theodore Roosevelt

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Regards,

Idriah Safriza :)

FYP Week 7 - PCB design for Blood Pressure circuit

Moshi Moshi,

It is semester break week...!! I'm on a week holiday...Its so comfortable to stay at home...hehe :) Home sweet home.

So, for this week, I have been working on the Blood Pressure (BP) circuit. It is a bit difficult to find a working circuit that can operates accordingly. I keep on having trouble to find a complete BP circuit. At first I decided to make the BP circuit by referring to the link below: click here to download the pdf 

However after consultation with my supervisor, Madam Zabariah and discussion with the lab engineer, Mr. Faizal, I have come to a decision to make the BP circuit exactly like the BP training board which is available in our Medical lab.

I've attached some images of the training board from our lab for your viewing purposes. This training board is use by the medical students to understand the working operation of the BP circuit. It may look simple but it is very expensive! Here have a look at this link to understand more on the KL-720 Biomedical Measurement System  click here to read more on this product :) 

What is the KL-720 Biomedical Measurement System

 Figure 1: KL-720 full set

• This equipment is intended for students to learn how to design specific measuring circuits and detect the basic physiological signals with practical operation. 

• Moreover, students can understand electrical characteristics of sensor and transducer explicitly. 

• The KL-720 contains nine modules, including Electrocardiogram Measurement, Electromyogram Measurement, Electrooculogram Measurement, Electroencephalogram Measurement, Blood Pressure Measurement, Photoplethysmogram Measurement, Respiratory Ventilation Detection, Pulse Meter and Body Impedance Detection.

• The sensors and transducers used in this equipment include pressure transducer, infrared photocoupler, strain gauge, temperature sensor and surface electrode.

• Each module has many test points for changing the frequency bandwidth and amplifier’s gain. Thus students can understand the correlation between physiological signal and each circuit stage.

So, below are the pictures of the KL-75005 Blood Pressure Measurement Module: 

Figure 2: Top View of the Blood Pressure Training Board

Figure 3: Back View of the Blood Pressure Training Board

I had manage to redraw the PCB layout and I have to say it is not easy to trace the PCB board as the lines are so fine and confusing...haha I would like to thank my friend, Sharavanan Shanmugaratnam, for coming all the way from Seremban just to assist me on the PCB layout tracing. Together we manage to redraw the PCB layout faster, but it still took us 4 hours to accomplish it...exhausting.....!! So here you go, the sketches done from the PCB tracing (Sorry for the ugly hand drawing schematic) :p

Figure 4: BP Schematic diagram

So, that is all on my progress for this week. Next, I will be working on the PCB designing and PCB production for the Blood Pressure circuit. Wish me luck....!! Hope to see you guys soon....Take care...

Tata.......................   <3

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Quote of the day....!

The future lies before you, like paths of pure white snow.  Be careful how you tread it, for every step will show.  ~Author Unknown

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Regards,

Idriah Safriza Bte Idris Chin  (',' )v