💘Heart rate monitor

After many hours of misery and trying to figure out how photoplethysmography works I was finally able to get a working prototype of a heart rate monitor.
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I was testing it and my watch showed me around 72 BPM and my prototype said something between 70 and 73 so I call that a victory. It is important to point out that your heart rate can change rapidly fast.
(In the second picture you can see the output of my program, but it is in my native language: “MOMENTÁLNÍ TEP” means “The current heart rate” and “STABILIZOVANÝ PRŮMĚR” means “the average heart rate”)
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Photoplethysmography comes with many problems like motion artefacts which are kinda difficult to solve. You have to do a lot of filtering on your data till you get somehow good results.
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At the end of the day the main idea is pretty simple: you shine light through your finger and due to basic principles of spectroscopy you can measure the changes in the light on the other side of the finger.

Well that was my journey! :D
The next steps would be to design a case for it so i can limit the motion artefacts.
Stay safe! ✨💘