Pulse oximeter

A project log for Medical tricorder

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M. BindhammerM. Bindhammer 09/15/2015 at 17:170 Comments

The current heart beat monitor works quite well, but a pulse oximeter would be better to get the pulse rate and the saturation of peripheral oxygen SpO2.

After a lot of research I found this promising reflective pulse oximeter design. The circuit outputs amongst other things directly the peak IR and red light voltages. The simple equation

is used, and S represents the value of StO2 in a calibration table.

I will use a commercially available pulse oximeter to approximate a function of the saturation of peripheral oxygen depending on S.

Redrawn and slightly modified schematic:

Next step will be to build a prototype and see how it works.

PCB layout of the prototype: