Hello everyone. I am currently doing a personal ECG project. I would like to design a two electrode portable ECG that I can bring around. I followed this circuit from cs.washington.edu (credits to them) .

I have attached the photo with this post. I am unable to get any ECG wave from the circuit. I seem to be getting baseline drifts when I put my fingers on the electrode. I hooked up the circuit to an Arduino uno and adafruit tft board. The arduino and lcd work fine. I do not understand how the circuit functions and what mistake am I making. please help. Thank you in advance.

 

Normally an electrode is connected between the circuit ground and the right leg. In your circuit this is probably the virtual ground.

This gets rid of common mode noise such as power line pickup.

 

There is a large difference in signal level between conductive gel pads 2 inches from the heart and finger pressure 3 feet away. Are you sure what you are tying to do is possible?

ak

 

Normally an electrode is connected between the circuit ground and the right leg. In your circuit this is probably the virtual ground.

This gets rid of common mode noise such as power line pickup.

Thank you for the quick reply. I understand it better now!

There is a large difference in signal level between conductive gel pads 2 inches from the heart and finger pressure 3 feet away. Are you sure what you are tying to do is possible?

ak

Yes I am sure. I came across this product called Alivecor (https://www.alivecor.com) and so I was interested to build one like this. This is the completed circuit the talented people from cs.washington.edu came up with. They were able to get the trace from their input. The resulting oscilloscope is reading is here too. I have attached the photos with this thread. Once I get back from work I can post my completed circuit and the oscilloscope reading. Thank you!