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Author Topic: Arduino ECG/EKG Heart Rate Monitor  (Read 17064 times)
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The goal of this project is to create a device that can be worn by patient that would monitor the patients heart rate via ECG signals. The arduino would then calculate the patient's heart rate and transmit it wirelessly to a receiver. The receiver would than be connected to a PC which logs the data into a database, issue alerts, display data, etc

This post is basically a log of my current project

[size=20]Current status: 5%[/size]
[size=20]-ECG Circuit - prototype completed[/size]
[size=20]-Wireless communication - not completed
-Receiver -not completed
-Main program on PC - not completed[/size]

Possible additions:
-temperature monitoring

Pls feel free to leave comments, questions, and siggestions

Thanks,
Bigdinotech
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[size=20]ECG Circuit Prototype[/size]


[media]http://www.youtube.com/watch?v=UiOBTPCcecY[/media]


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I want to see this completed so badly...=D Get to work!
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Please post you schematic for the sensor hookup

What instrument Amp are you using?

thanks
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Hopefully you are using precautions like 1 Mohm series resistor on all leads going to your skin. If you've got the Arduino plugged in via USB, that ground is connected to your PC ground, which is connected to your wall outlet AC ground. And the electrodes are taped right over your heart so the lethal current threshold to trigger ventricular fibrillation is much lower than normal... accidents can happen!  I think commercial EKG equipment always uses optoisolators for complete electrical isolation.
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Quote
Please post you schematic for the sensor hookup

What instrument Amp are you using?

thanks
I am using a Texas Instruments INA2126PG4 which I purchased from Mouser.
The circuit is pretty much based on the datasheet.
I would post a schematic but I need to find the Eagle file for this part first.
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I did a battery-powered heartrate monitor almost 20 years ago, and the completed unit is still on my shelf. Your post inspired me to take a few photos of my lab notebook, and the unit itself. I posted them here:

http://bealecorner.org/best/measure/EKG/

Since it was battery powered and transmitted the output via RF there was no problem with electrical hazards from ground loops, etc.  I made my own instrumentation amp from a quad LP324N opamp.  It was cheap :-).  No doubt there are better options these days.

I was just measuring heartrate so I just did one pulse per beat. To actually record the full EKG waveform you'd have to encode that somehow, probably as a FM tone-encoded signal.
« Last Edit: December 17, 2010, 05:15:37 pm by jbeale » Logged

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Quote
Hopefully you are using precautions like 1 Mohm series resistor on all leads going to your skin. If you've got the Arduino plugged in via USB, that ground is connected to your PC ground, which is connected to your wall outlet AC ground. And the electrodes are taped right over your heart so the lethal current threshold to trigger ventricular fibrillation is much lower than normal... accidents can happen!  I think commercial EKG equipment always uses optoisolators for complete electrical isolation.

Thanks for the advice.
I made sure amplifier is battery powered but I forgot about the ground when I connected it to the Arduino. I will keep this in mind the next time I do some tests with this circuit.
The final design for the monitor will however be completely battery powered.  Only the receiver will be connected via USB to the PC, which will not have any electrodes.  
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I did a battery-powered heartrate monitor almost 20 years ago, and the completed unit is still on my shelf. Your post inspired me to take a few photos of my lab notebook, and the unit itself. I posted them here:

http://bealecorner.org/best/measure/EKG/

Since it was battery powered and transmitted the output via RF there was no problem with electrical hazards from ground loops, etc.

I was just measuring heartrate so I just did one pulse per beat. To actually record the full EKG waveform you'd have to encode that somehow, probably as a FM tone-encoded signal.

Thats pretty cool.
Currently, the arduino only calculates the heart rate.
I did this by measuring the time between pulses.
I can use the 10-bit ADC from the arduino to read then send the waveform. but I first need to figure out the wireless communication using the Xbee.
I also want to be able to have more than one device transmitting at the same time.
So I am trying to keeps thing simple for now.
That's why I am trying to minimize the amount of data that would be sent to the receiver.
In the future I do plan to send data on the full waveform but that would really complicate things at the receiver end.
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Good luck with your project!

The other thing to remember when testing things, is just about any AC-line powered oscilloscope probe will have the ground lead connected to AC earth ground. Trying to avoid that by using a "ground cheater" plug on the scope power cord is even more dangerous. They drilled that into us in the medical electronics course I took, when they reviewed safety.
« Last Edit: December 17, 2010, 06:19:30 pm by jbeale » Logged

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Did you see the ECG example with right leg drive
 on the INA2128 spec sheet?
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I don't see an example with the Right Leg Driver in the DataSheet, But from what I understand, this circuit is for noise filtering purposes.
How many gain stages do you have?
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Its on the INA2128 Data sheet from TI

Page 10, Fig 6

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Does anyone know the amount of Leakage current that the Arduino Pro Mini can handle before it is damaged, I am not sure which value it corresponds to on the Data Sheet
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Hey,

Thanks for the response, but I believe a work-around solution was provided a few posts above (Using 1Mohm Resistors across, the input to the Electrodes) . In any case, if you would happen to know what the value is that I should look out for that would be helpful, because this determines where I can place my bandpass filter.
Thanks
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